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NASA is seeking to challenge the GrabCAD Community by sponsoring an open competition in which participants design a bucket drum for RASSOR that will provide the maximum amount of regolith extraction and retention while remaining free of obstructions during loading and unloading.
Regolith excavation is desired in future space missions for the purpose of In Situ Resource Utilization (ISRU) to make local commodities, such as propellants and breathing air, and to pursue construction operations.
RASSOR is a teleoperated mobile robotic platform with a unique space regolith excavation capability. Its design incorporates net-zero reaction force, thus allowing it to load, haul, and dump space regolith under extremely low gravity conditions with high reliability.
RASSOR uses counterrotating bucket drums on opposing arms to provide near-zero horizontal and minimal vertical net reaction force so that excavation is not reliant on the traction or weight of the mobility system to provide a reaction force to counteract the excavation force in low-gravity environments.
During loading, the bucket drums excavate soil/regolith by scoops mounted on the drums exteriors that sequentially take multiple cuts of soil/regolith while rotating at approximately 20 revolutions per minute. Inside the hollow drums are baffles that trap the regolith and prevent it from falling back out of the scoops. During hauling, the bucket drums are raised by rotating the arms to provide clearance above the surface being excavated. The mobility platform can then travel while the soil/regolith remains in the raised bucket drums. When the excavator reaches the dump location, the bucket drums are commanded to reverse their direction of rotation, which causes soil/regolith to be expelled out of each successive scoop.
For more information: https://technology.nasa.gov/patent/KSC-TOPS-7
RASSOR 1.0/1.5:
https://www.youtube.com/watch?v=d3zRvl2LYJ4&feature=emb_logo
RASSOR 2.0:
https://www.youtube.com/watch?v=rAIw7a2VfQ0
JUDGING CRITERIA
1. Successful designs will have a fill ratio higher than 50%.
2. Short description of how your design works and intended fill ratio
3. Is the design real? Can the design work? Can it actually be created?
4. Meets dimension requirements
5. If the engineer can provide a simulation of the regolith grain, that is a plus.
Requirements needed for Submission:
Maximum total width of scoops engaged at any given time: 175 mm
Maximum bucket drum mass: 5 kg
Maximum bucket drum diameter: 450 mm
Maximum bucket drum length: 360 mm
A minimum volume of regolith captured: 17.6 liters
Submission File Formats
Renderings
STEP of design(s)
Final design STL
Short description of design/how it works
ENTERING THE COMPETITION:
SUBMITTING AN ENTRY
AWARDING THE WINNERS
We will release the finalists before the announcement of the winners to give the Community an opportunity to share their favorites in the comments, discuss concerns, and allow time for any testing or analysis by the Jury. The Jury will take the feedback into consideration when picking the winners.
Schedule
$7000 in Prizes
$3000
$2000
$1000
$750
$250
This challenge is sponsored by the NASA Lunar Surface Innovation Initiative (LSII) which is a technology development portfolio to enable human and robotic exploration on the Moon and future operations on Mars.
The RASSOR excavator was developed at NASA - Kennedy Space Center’s Swamp Works. Swamp Works is a technology development group with expertise in In-Situ Resource Utilization. The Swamp Works team uses lean and rapid design and development processes to develop prototype hardware for future missions.
Brad Buckles
Andrew Nick
Drew Smith
Jason SchulerHave an awesome idea for this competition? Want to win cool prizes? Sign-up now to upload your entries.
If you don't receive the email within an hour (and you've checked your Spam folder), email us as confirmation@grabcad.com.
251 comments
Tommy Mueller almost 5 years ago
Looks like an excellent challenge, thanks for partnering up to make this happen! Pretty sure I got the scope of the challenge, but I have two quick questions:
…
1) Is there an official 3D model of the RASSOR (minus the current drum) or at least some 2D drawings that us participants can use as a reference for design compatibility?
…
2) What is the current “Fill Ratio” using the existing drum?
Daniel Rutkowski almost 5 years ago
I have a few questions on the details of the current drum system.
1) How are the drums mounted/driven?
1b) Are the designs required to account for the mount/drive?
2) What are the material/weight limitations of the designs?
3) Could you provide some information or a video of the current challenges associated with the current design?
Thank you
sanjay padvi almost 5 years ago
I am bit confused statement in "Schedule" "This Challenge ends on March 16th, 2020 (23:59 EST.) " ....means ...what is deadline?
Jason Schuler almost 5 years ago
Tommy:
1.) We do not have any CAD that we can share of the RASSOR geometry. This challenge is intended to focus on the bucket drum geometry that interacts with the dirt. The entries do not need to include details for interfacing with RASSOR.
2.) The current fill ratio is between 35% - 40%
Jason Schuler almost 5 years ago
Daniel:
1. a&b) See response to Tommy's question #1 above.
2.) The maximum mass for the design is 5kg. The material choice is open however the existing drum uses a combination of carbon fiber and aluminum.
3.) The current drum works without any issues however if we can increase the fill ratio it could save significant time/energy during a mission.
Jason Schuler almost 5 years ago
Sanjay:
Thank you for catching that. It was a typo that has been fixed. The deadline is April 20th (23:59 EST)
joey bevilacqua almost 5 years ago
How do you define the fill ratio?
SHIKHAR SARASWAT almost 5 years ago
Really excited to participate in this..!!
Paul Desjardins almost 5 years ago
The maximum mass is 5kg. The existing drum combines carbon fiber and aluminum. This call for a new design of digging device. I would suggest that the robot first scoops material in the (solid and resistant) drum to increase weight and allow drilling device of pretty well known design.
Sava Savov almost 5 years ago
So, there are four drums and the requirements are for one of them? Or the requirements are for one "total drum" for each of the two sides where the machine digs?
Clint Gates almost 5 years ago
Why is the design a combined digger and hopper? It's more efficient to have separate machines for the jobs. This applies to farming, mining, factories, and much more.
Andrew Lesh almost 5 years ago
Are there any CAD files or images you can share of RASSOR 2.0's drum? The IEEE paper you linked has an image of interior geometry of the RASSOR 1.0 drum (https://www.researchgate.net/profile/Rachel_Cox12/publication/261248231/figure/fig2/AS:702678908805125@1544543115946/Bucket-drum-without-end-cap-to-show-baffles-RASSORs-solution-to-the-issue-of.jpg), so it would be really helpful to see the geometry of the second revision as well.
Andrew Lesh almost 5 years ago
Also, what is the fill ratio of each RASSOR drum revision tested so far?
Dodi Budzyn almost 5 years ago
Great challenge! I was trying to figure it out from rules but I still have dubts so I will just ask: are non US citizens and people who don't live in US allowed to take part in the competition? I am asking for all Europeans here:) Thanks in advance if somebody helps to figure it out!
Dhruv Gandhi almost 5 years ago
does the bucket drum size specifications refer to the inner storage drum or the whole thing?
Kamen Rusev almost 5 years ago
My question is: it will work only on sand type of material or gravel and all kind of rock shapes?
Jeffrey poe almost 5 years ago
@ClintGates Because the extra weight and space would be exponentially more expensive. Also because a combine harvester doesn't fit in the shuttle cargo hold.
Clint Gates almost 5 years ago
@Jeffrey poe Reinventing the wheel should not be the goal.
The current design has great mobility but will clog up because it does not have anything to grind the material. The only limiting factor to aggregate size is the openings of the buckets. While the base request for design is for increased fill of the barrel, the requirements also list, "5. If the engineer can provide a simulation of the regolith grain, that is a plus." This implies the current design has issues dealing with clogging, and material larger and more solid than loose soil. The current design will also suffer from torsion of the arms and barrels.
Reduce the RASSOR size.
Use existing boring / grinding technology to dig.
Send at least one Bucket Drone along with the RASSOR. Making more should be a priority once onsite.
Only Bucket Drones, aka Trucks, should be used to transport material.
Remember, sometimes smaller is better. Use the weight and dimension restrictions for multiple proper tools instead of one tool that will break itself.
Tucker Albright almost 5 years ago
Hi Jason, I have three questions.
1. What is the torque and speed of the drum's drive system? Are you able to provide a torque/speed/power/efficiency curve? I understand we don't have to interface with the drive system for this challenge, but I would like to know these parameters as they effect the performance of the drum itself (i.e. too large a scoop may stall the system).
2. Which type of lunar sites do you intend to mine from? Specifically, I'm interested in the particle size of your target sediment. Which version of lunar soil simulant (i.e. coarse JSC-1AC or fine JSC-1AF, etc) are you most interested in mining? Are you able to provide any material data?
3. How fast do you plan to 'traverse' a digging site? In other words, what is the linear travel speed (not rotational speed) of the drum or rover so that it acquires new dirt? In which direction does the drum travel?
Many thanks.
Dhruv Gandhi almost 5 years ago
@kamen Regolith is the material on the surface of a planet/moon. it can be measure from 120 microns to 0.8 cm (got those figures from google)
Joseph Gallagher almost 5 years ago
Does the approach used to mount the drum to the arm/drive system allow for the possibility of a stationary core to the drum, which does not rotate with the rest of the body?
Jean Alain Alphonse almost 5 years ago
How hard is the Regolith on the Mohs scale?
Daniel Voloshkevych almost 5 years ago
Is it allowed to be a student to take part of this challenge?
Jason Homrighaus almost 5 years ago
How are you defining "Fill Ratio"? Is that based on the total volume of the enclosing Boundary? Total Volume of the Open space of the Model? etc?
Kesa almost 5 years ago
Daniel, You are allowed to enter this challenge.
philippe jamel almost 5 years ago
hello you can imagine a magnet neodym inside to collect more powder : it is a good 3d digger i see but powder is difficult : no water, to collect we put water
ernie ascherman almost 5 years ago
Not looking to make a full submission but have an idea for the fill ratio issue: make a spiral shape inside the cylinder to keep the regolith from falling back out.
Anirudh Palaiya almost 5 years ago
Do you have to be 18 years or older to participate in this challenge?
Daniel Voloshkevych almost 5 years ago
Anirudh, no! ;) I am 17teen :)
Aadarsh K s almost 5 years ago
Setup a hydraulic drill under the robot
This drill help the robot to decrease the hardness of the soil
When the hardness of the soil decreases vaccum the soil using a powerful vaccum
Pump
Aadarsh K s almost 5 years ago
Setup a vaccum pump inside the drum so the soil will not go out of the drum
Sava Savov almost 5 years ago
But there is already vacuum up there on the Moon :)
Damoor Sahami almost 5 years ago
I'm no good at CAD. But my idea would be to replicate a sea (snail) shell, with a "double layered screw", one (outer layer) that drills up the material and then falls into the inner layer screw which is only a sealed container. The idea with this would also be to be able to drill deeper.
Gewang Aquino almost 5 years ago
Hi, question. Are we allow to use other softwares like sketchup?
Daniel Voloshkevych almost 5 years ago
yes, I using Blender for that ;)
Raul Santos almost 5 years ago
Algum software para simulação do grão de regolito?
Divy patel almost 5 years ago
Do we have to use a 3d software for submission?
Kesa almost 5 years ago
@Divy you have to create a CAD File so yes a 3D Software is required to create your submission
Jacob Mosier almost 5 years ago
Anyone know if there is a required/suggested materiel?
RocketNut almost 5 years ago
I can not read web link.because it is in German.
RocketNut almost 5 years ago
An I quote from challenge out lined above:::
======================
During loading, the bucket drums excavate soil/regolith by scoops mounted on the drums exteriors that sequentially take multiple cuts of soil/regolith while rotating at approximately 20 revolutions per minute. Inside the hollow drums are baffles that trap the regolith and prevent it from falling back out of the scoops. During hauling, the bucket drums are raised by rotating the arms to provide clearance above the surface being excavated. The mobility platform can then travel while the soil/regolith remains in the raised bucket drums. When the excavator reaches the dump location, the bucket drums are commanded to reverse their direction of rotation, which causes soil/regolith to be expelled out of each successive scoop.
=============
Meaning the drum is the correct.
Trevor Owens almost 5 years ago
So what is the minimum age required?
Ananth Narayan almost 5 years ago
Does the concept of bucket has to be modified or any new idea for the same purpose can be laid.?
Bintang Farhan almost 5 years ago
can we add electrical component to the design?
Narendiran Rajasekar almost 5 years ago
yes we can add.
Trevor Jamieson almost 5 years ago
Why two rotating drums? Could this not also be accomplished by dragging a scoop/bucket behind the "rover" body? Similar concept to a scraper.
A single arm attached near the midpoint would still allow for the device to be self righting. Easier to clean if clogged with wet material. Not really affected by material size being "mined". Fewer moving parts. Potentially faster.
Trevor Owens almost 5 years ago
How do you make a (Rassor) Drum that light?! Even out of carbon fiber!
mahboub el idrissi zakaria almost 5 years ago
I want to participate, can anyone help me how
V.Novacov almost 5 years ago
Could you explain,how many drums have to be or what is the overal size of the drums( one or two).
Jason Homrighaus almost 5 years ago
All of the information is in the above description under requirements, the only thing not immediately clear is that the requirements are for 1 drum(there will be 4 on the machine)
walter pfeiffer almost 5 years ago
I think it is better to send an origami shop, with actuators on each leg to make it mobile and use it as a controlled environment to work.
Outside put solar panels and inside a series of tesla charging modules to make the load wireless and that the work is done without stopping.
We would put a conveyor belts to remove the waste material and when setting up several tents a large mobile area could be covered.
❤☜(ﾟヮﾟ☜)
rahadyan muhammad almost 5 years ago
Hi Do we have to design the opening with minimum 5cm width(like older design) or we could make it smaller?
Captain Anonymous almost 5 years ago
I don't like the design of the RASSOR rigolith excavator. Digging in dry sand is one thing, fairly easy. Digging in a field of mixed sand and and rocks of different shapes and sizes will be comletely different and more difficult. Add a little moisture from water or some other liquid and clumping or sticking to the inside will be a huge problem.
The drums as they are, are prone to clogging with rocks or clumps of rigolith. Some rocks may make it in one way but then turn sideways when inside and form a clog.
What happens when one side doesn't pick up anything and is empty? The whole device will be off balance and prone to tip on it's side.
I feel a more open claw or bucket is needed. Something that can easily be cleaned out, no matter the consequence
Jason Homrighaus almost 5 years ago
There is no rain on the Moon. Also reglith is a fairly fine material even its largest particles are quite small generally less than 1cm.
Daniel Voloshkevych almost 5 years ago
Captain Anonymous - NO your idea is completly Wrong!
Captain Anonymous almost 5 years ago
We have no idea what we're going to run into on the surface moon or elsewhere. We've only landed on the moon around six times and barely scratched it's surface. Once we try and dig more than a couple inches everything could, and probably will, change. No it does not rain on the moon, but there are regions that still contain ice. If they are going to dig for ice with this device so they can produce oxygen, the drums will clog, guaranteed.
Jason Homrighaus almost 5 years ago
I don't know Cap, those nasa guys seem pretty confident in their design parameters.
Jason Homrighaus almost 5 years ago
I mean the surface of the moon is effectively a vacuum which pretty much eliminates the possibility of moisture.
Jason Homrighaus almost 5 years ago
Does the Outside Diameter have to be fixed at all times or is it possible for it to have a Closed, Digging mode that is 450 and an open, Empty mode that is larger than 450?
Jason Homrighaus almost 5 years ago
Does the Drive system Use a Stepper/Feedback system allowing it to be positioned at a particular point in its rotation? Does it have the ability to operate at different speeds or is it a fixed speed setup?
javad kazemi almost 5 years ago
Hi
I am proud to work with good designers $ And thanks for the patience and accuracy of Julie's comments .
I have the experience of designing a mahjong sample last year.
Thank you so much for trusting a large group of NASA engineers and managers.
I had three questions about the new challenge.
1. Should the sampler sample from the surface, or do the layers below the soil surface sample? Or how deep should it penetrate the soil?
2. Is the 5kg weight based on the gravity of the moon or the planet's gravity?
3. How many drives can the drive bucket be able to drive?
With respect
javad kazemi
Briac LE RAY almost 5 years ago
Hello,
I am asking the community working on this project.
I do not have any license for a CAD (I wish I could use SolidWorks) and thus am struggling to try to have FreeCAD work, which is not a very successful task.
Could you share which tools you are using for doing your prototypes, and which tool you use to make the animations? :)
Cheers!
Briac
Jason Homrighaus almost 5 years ago
You might look at fusion 360. It is free to students, hobbists, and startups. Also Houdini offered a free non commercial version that is quite powerful but has a fairly steep learning curve. Lastly google sketch up is free.
Captain Anonymous almost 5 years ago
Some others I might add are, Blender which is my go to tool kit for CAD. www.blender.org. An excellent program that will do everything you wish and it's absolutely free. Others that are equally as powerful are a couple of the more prominent game engines, Unreal Engine (www.unrealengine.com) and Unity (www.unity.com). Both of these are also free to download and use. But these two have licensing agreements when you make over a certain amount of money with them.
No matter which program you end up with, there will be a steep learning curve. If you're new to CAD, expect at least a thousand of hours of learning to be some what proficient.
Briac LE RAY almost 5 years ago
Thank you for your comments Jason and Capt'ain! Much appreciated!
Flaviano Crespi almost 5 years ago
@Briac LE RAY
In addition to the other programs already reported, you could use: Creo Elements / Direct Modeling Express
It is available for download and free use.
It has a very rapid learning curve because it is totally non-parametric and history free.
You will be able to see the tutorials on Youtube.
It has the following limitations:
- max 60 parts (enough for this project)
- can export only in STL, not in STEP
Briac LE RAY almost 5 years ago
Thank you Flaviano I appreciate your help. :)
Dylan Domb almost 5 years ago
Is there an axle that goes through the drum and if so, what is its diameter?
abhishek singh almost 5 years ago
can there be multiple people in a team?
BENJAMIN OKELLO almost 5 years ago
Interesting challenge from NASA, looking forward to submitting my design.
Flop berry almost 5 years ago
what is the problem with NASAs design. What is the reason to find a new design? Please let us know what your design is lacking for us to improve it.
Thank you
Jacob Mosier almost 5 years ago
"Maximum total width of scoops engaged at any given time: 175 mm" is this dimension parallel with the diameter or the width of the drum?
Ben S almost 5 years ago
Does the mass of any welds count against the 5kg restriction?
Joe Z almost 5 years ago
Can anyone recommend software to run the simulation?
Sava Savov almost 5 years ago
@Joe Z https://www.youtube.com/watch?v=dwe91ula31g
Daniel Voloshkevych almost 5 years ago
must be the design symmetric?
Levi Owens almost 5 years ago
so why do you have to be over 18 to be eligible to be considered?
Daniel Voloshkevych almost 5 years ago
Jeff : what do you mean?
Levi Owens almost 5 years ago
why is the reason you have to be 18 to win?
Brady White almost 5 years ago
What does STEP and STL mean?
Jason Homrighaus almost 5 years ago
Brandy, They are 3D File Formats,
Jeff, If I had to guess the reason is that in entering the contest one is surrendering certain legal rights and claims to the intellectual property that is created and as such entrants would be required to be of age to legally release those rights as with most legally binding contracts.
Jason Homrighaus almost 5 years ago
Just a Side, no criticism intended and I know there is a lot going on, but it would sure be nice if the organizers spent a little more time responding to questions related to this contest. Some are silly but many are legit and the final outcome could only be improved with the information disseminated.
Daniel Voloshkevych almost 5 years ago
Jeff: i am 17. And a moderator has write to me that I can enter this challenge. And where you have see that information??? Because I don't see it EVERYWHERE XD
Kesa almost 5 years ago
If you have any questions that haven't been answered please let me know by sending a private message. Some may have been lost in the volume of messages in this forum. I will try to get them answered as fast as possible.
Thank you
Andrew Nick almost 5 years ago
Here is some answers to some questions in the comments:
How are you defining "Fill Ratio"? Is that based on the total volume of the enclosing Boundary? Total Volume of the Open space of the Model? etc?
Fill ratio is volume of regolith collected versus total internal volume.
Does the Drive system Use a Stepper/Feedback system allowing it to be positioned at a particular point in its rotation?
Yes we have closed loop position and velocity control.
Does the drive system have the ability to operate at different speeds or is it a fixed speed setup?
Yes we have closed loop position and velocity control. We can reliably operate through a full range of velocity.
Does the Outside Diameter in the specification have to be fixed at all times or is it possible for it too, for example, have a Closed/Storage mode that is 450 and an open, Digging or Empty mode that is larger than 450?
The 450mm diameter is a maximum, but it can be smaller and change size during operation if needed, as long as it doesn’t exceed the maximum diameter.
Does the system have any provision for Electrical, Mechanical, Hydraulic or Pneumatic actuation of Components built within the Drum? or do any actuations have to be solely powered by the forward or reverse rotation of the input shaft?
It does not currently, but there are no restrictions for incorporating actuations inside, but keep I mind it is a continuously rotated joint. So for example a slip ring would be required to pass electrical connections.
Is there an input shaft that should be designed around or is there a fixed flange of some fixed dimension that needs to be accommodated?
The bucket drum is currently driven from a flange on the side and does not protrude internally. The inside is up to you. However, if your design defines the input actuation interface include your design intent in your explanation.
Does shaft volume need to be accounted for in the drum filling ratio?
The bucket drum is currently driven from a flange on the side and does not protrude internally. The inside is up to you. However, if your design defines the input actuation interface include your design intent in your explanation.
TristanDC almost 5 years ago
I'm a bit puzzled by the whole concept for RASSOR, so I thought I'd "throw" this idea out there:
Why collect 'small' amounts of regolith that then have to be transported numerous times by a small rover back to the factory?
Throw it.
Much like a snow blower ( aka snow thrower) that us Canucks and northern Americans are so familiar with.
Snowblowers can throw 25 to 40 ft. On the moon with 1/6th the gravity and no atmosphere you'll get great distance.
You could put up a screen at the collection site (if needed) to catch and funnel it into your factory.
Covering over the new moon base structure with a protective layer of regolith will be a cinch.
Incidentally, the blade on a snow blower rotates/scrolls in from right side and in from left side (opposing direction cancelling out force from opposite side).
For my 2 cents, I think NASA would be better off creating an all-purpose vehicle much like a farm tractor that is modular / can have different tools attached to it to achieve specific functions.
Ananth Narayan almost 5 years ago
Does the weight should not exceed 5kg for the whole system or for the single bucket with 3 or 4 scoops. Greatly confused with the term bucket.
Ravi Maurya almost 5 years ago
Jury, could you please specify the maximum dimension of the Regolith rock that is being loaded inside the drum. I have been reading a lot about regolith on the moon. Some website says the diameter of the regolith rock is in between 0.1 cm to 1 cm whereas some website specifies up to 10 cm. Even in the research paper provided along with description about RASSOR 1.0/1.5 says that it was designed to accommodate stone up to 5 cm in diameter. All the videos shared show that the RASSOR is being tested with the sand grain (whose maximum diameter is only 2 mm).
Nolan Lach almost 5 years ago
It should be like an auger but instead of throwing the dirt, it collects it. This also means it can go further into the moons surface and collect more resources.
Jason Schuler almost 5 years ago
Ananth: The 5kg mass limit is for one bucket drum. In the example of RASSOR 2.0 there are 4 bucket drums, 2 on the front 2 on the back.
Ravi: We did not specify a maximum rock or scoop size for this challenge. The primary goal for RASSOR is to excavate the granular regolith, if there are larger pebbles mixed in we want to accommodate them but they will likely have to be filtered out before the regolith enters the processing plant that will extract the oxygen or water. During testing we have seen that taking a full scoop (~5cm) of regolith can cause it to jam and not fully enter the drum. Therefore we try to actively limit the digging depth to roughly half the scoop height (~ 2.5cm).
Tommy Mueller almost 5 years ago
24 hours left!
Filip Šabacký almost 5 years ago
on the way
Sunoj Kashyap almost 5 years ago
Waiting for the Results ! !!!!! ! !!!!! !
Sava Savov almost 5 years ago
There are hard days and nights ahead for the jury to look at all these projects for one week. I suspect that it will be more than one week until first results come up. Maybe two weeks will pass...
MiDesys almost 5 years ago
Just came on my mind. Guys what to you think of idea for simulating moon gravity in way that you put water in some container and inside some material, plastic granules which have little bit bigger density for representing the regolith?
Tommy Mueller almost 5 years ago
So if 1000 pounds of salt in 180 gallons of water creates a 30% salt solution, enabling you to float effortlessly atop the water. This can create an anti-gravity environment, as all weight and tension can be dropped.
...
My Guess: Maybe adding an appropriate amount of salt to help your experiment?
Vaclav Lhota almost 5 years ago
Not bad idea. A friend of mine was thinking about similar conditions. No purely in water, just make the substance wet a bit. But something tells me you won’t get anything reliable. I could try it with a 1:3 scaled model I want to print if my design gets the chance:)
Sava Savov almost 5 years ago
I think it is possible with any material heaver than water - if a hollow balls are used - with adjusting the size of the balls , different gravity can be simulated.
Sava Savov almost 5 years ago
But rotating the drum in water....
MiDesys almost 5 years ago
Snow globe : https://youtu.be/1xB4RYzyMu0
Vaclav Lhota almost 5 years ago
But the snow travels here almost like in zero gravity:)
Sava Savov almost 5 years ago
Yes, but when we move something in the water (the drum), the water starts to move too and that will affect the trajectories of the granules, and the drum will be full of water which must be replaced by the granules ... I don't know... Probably a magnetic field in vacuum can be used to simulate the conditions - here I go in field in which do not know much - in fact nothing :)
Dexter Gomes almost 5 years ago
Applying this principle also might help https://m.youtube.com/watch?v=My4RA5I0FKs
Dexter Gomes almost 5 years ago
Some fine-tuning will be needed 😅
geo almost 5 years ago
@Dexter: amazing video. I never see this effect.
Bintang Farhan almost 5 years ago
Does anybody know how many finalist will be chosen?
Vikranth Guda almost 5 years ago
HELP! i just missed the deadline. Pls is there any chance to send the design? I can send it right away
Vikranth Guda almost 5 years ago
its only 22:15 est now and the deadline is till 23:59 est right? Pls somebody tell me whom to contact...
James Ehlers almost 5 years ago
Same question as Vikranth. It's only 11:18 EST and the rules say we have until 11:59 EST but I can't submit.
Paul S. almost 5 years ago
Well, 23:00 isn't 23:59 Eastern Standard Time (my time zone).
The door shut down one hour ahead of the deadline.
Ankush Sharma almost 5 years ago
the rules are rules, its 11:19 est and my entries were uploading, I spent so much time and you guys have closed the portal, this is not fair, please open it
Ankush Sharma almost 5 years ago
who ever is the concerned person please look into it, deadline is 23:59 and not 23:00 est
Ankush Sharma almost 5 years ago
still 30 mins left, I was uploading my entry and its heart breaking to see such irresponsible behaviour honestly, rules are rules.
Staffan almost 5 years ago
Closed early, couldn't submit entry.
Fred Lee almost 5 years ago
Wow, I spent a lot of time and effort to make this deadline. I'm devastated!
Ankush Sharma over 4 years ago
GrabCad team please open it for 30 minutes so that all of us who are suffering from this early closure of submission portal could at least submit if not consider for final evaluation. We all have worked super hard and things like this really hurt.
Tim W over 4 years ago
I would not mind a quick extension on that deadline as well...
Vikranth Guda over 4 years ago
Exactly Ankush. Extend the deadline just enough to compensate for the early closure.
Jason Schuler over 4 years ago
*** If you were unable to upload your entry because of the early cutoff please send me a private message. I will work with the GrabCAD team to make sure we give you a chance to upload. ***
I am blown away by the response to this challenge! There are so many innovative and high quality entries. The jury will definitely have a tough time on this one!
Bintang Farhan over 4 years ago
I've submitted my work, but there's no simulation in it. I still want to show illustration of how the design work, I 3D Printed the parts and makes videos of it. Can I still add the videos to my submission? The design is not and will not change
Ankush Sharma over 4 years ago
@Jason Schuler thank you sir for responding, I hope that Grabcad reacts positively by extending the deadline so that we all can submit our entries.
Kesa over 4 years ago
Attenetion, We heard that some people were unable to upload their models due to the Challenge closing 2 hours earlier than it should have. We have reopened the challenge so people have a chance to upload their models. We apologize for this inconvenience
Ankush Sharma over 4 years ago
Thank you
Tim W over 4 years ago
Thank you Kesa.
Sava Savov over 4 years ago
I hope it is allowed for all to update their entries in the reopened period, too? - I am asking because I updated mine.
Kesa over 4 years ago
Thats fine Sava
Kesa over 4 years ago
We have closed the entries for the NASA Challenge. Thank you for everyone who participated in the challenge, we will let you know the top finalists next week. Again thank you for the amazing entries.
Raul Santos over 4 years ago
the competition is over can i add a high resolution image to my design?
Ankush Sharma over 4 years ago
Thank you Kesa, I have upload the files before closure of the extended deadline but its not showing in the entries. Here is the link:
NASA RASSOR BUCKET DRUM
Can you confirm whether my entry has been submitted or not?
Sava Savov over 4 years ago
It was there 1 hour ago - it was the last entry, I think
Tommy Mueller over 4 years ago
I saw it there too Ankush Sharma
Ankush Sharma over 4 years ago
yeah, I don't know if this is a bug in the site thats causing it.
Tim W over 4 years ago
Did anyone else see that there was "about 12 hours left"? Shouldn't have waited until I was done with work.... anyway here was my project
Linked Rotating Buckets for NASA Regolith Challenge
Raul Santos over 4 years ago
posso atualizar imagens de meu design?
Levi Owens over 4 years ago
yeah, that was a little weird, because last night it said 13 hours left then this morning it said 11 hours left, and I know I slept for more than two hours. :)
Yuriy Voloshkevych over 4 years ago
when is the finalist announcement
Miftah Khan over 4 years ago
Great concept
Yuriy Voloshkevych over 4 years ago
where they will announce the finalists? Here in the comments or where? :)
Vaclav Lhota over 4 years ago
On board the ISS, Yuriy. We are all waiting for ya here
Yuriy Voloshkevych over 4 years ago
lol... what? why me? haha
Guillermo Altenhofer over 4 years ago
I think that the calculations should be done with an irregular grain and think what happens if we find a stone.
Vaclav Lhota over 4 years ago
No design will prevent from contact with a big piece of rock, unless it does some geo radar or area scan before. That’s why buckets turn max 20 rpm. If the shovel hits something, telemetry sends it, the program stops and executes a relevant sequence.
Yuriy Voloshkevych over 4 years ago
And its not our task to make a Design where NOTHING would stuck.
Kesa over 4 years ago
Hello everyone,
Just wanted to give everyone a heads up. Due to the amount of entries the judges need to evaluate in this challenge. We will be announcing the finalists by Friday this week. Thank you for your patience.
Best,
Kesa
GrabCAD Community Manager
Vaclav Lhota over 4 years ago
Fair enough, but don't miss the launch:)
Yuriy Voloshkevych over 4 years ago
Haha good one. ;)
Brandon Waldaias over 4 years ago
👍👍
Trevor Owens over 4 years ago
sounds good!
Yuriy Voloshkevych over 4 years ago
is it true that the finalist will be announce today? :D Or are our jobs soooo good, that they need still 2 more weeks? :P
Vaclav Lhota over 4 years ago
No Yuriy, Kesa only needs more time to gently express that the jury needs one more week. Just be patient, look into the sky and have a nice cup of tea...
Yuriy Voloshkevych over 4 years ago
oh okay thanks :) yes I will. :)
Kesa over 4 years ago
Finalists are now Announced. Thanks for participating in the Challenge!
Ankush Sharma over 4 years ago
So many entries with great simulations and I'm surprised to see the some entries with least info being selected. Anyway congrats finalists.
Vaclav Lhota over 4 years ago
Good luck to everybody!
Yuriy Voloshkevych over 4 years ago
I have great sims but they didnt want my entries :/
Ankush Sharma over 4 years ago
I'm surprised to see entries with hypothetical and no simulation based fill ratios being selected.
Kesa over 4 years ago
Remember to show good sportsmanship as the challenge is winding down to a close. Any entrants that show any toxic behavior will be suspended from GrabCAD.
Ankush Sharma over 4 years ago
Well I don't want to be the bad guy here, so would like to pitch the judges for one last time. Here is my entry NASA RASSOR BUCKET DRUM and would love to see if judges can give one last shot at it, it has a fill ratio of 76% with a meaningful simulation.
I'm not against anyone but I think the entries with more realistic and meaningful simulations of fill ratios and other stuff should be selected and there are many such entries beside mine.
Also I'm writing this because we were asked for our feedbacks.
Thank you.
Tommy Mueller over 4 years ago
Kesa +1
Yuriy Voloshkevych over 4 years ago
I am so surprised that they have selected many entries WITHOUT a simulation... but there was standing that simulations are a plus :(
Sava Savov over 4 years ago
And I was expecting that there will be almost one entry from the type: "the shovels fill a bucket and then the bucket turns when unloading", because it looks very effective way to operate.
Victor Production .com over 4 years ago
I am puzzled ! So list announced is just for shout, laugh and with rate your fellow participants :) ?
Boris Abdul over 4 years ago
Hey folks , you didnt loose your entire life .Live , create and enjoy the life and do not post weird messages here . A special congrats to @tommy mueller , I knew from the beginning that this guy has a creative beast inside , keep rocking mate !
Dexter Gomes over 4 years ago
Congratulations to all the finalists as well as all the other participants, great work!
Ares over 4 years ago
In my opinion, the Commission should give a short comment to each project to give everyone the opportunity to better understand why one project was rejected and another not. I don't want to make controversy and I don't want to be bad with anyone, but simply to learn from mistakes to improve in the future. In any case, congratulations to all for the published works. See you at the next challenge.
Yuriy Voloshkevych over 4 years ago
Ares: I agree! Because I for example I have nice simulations but they didnt take it
Juan Ventura over 4 years ago
Congratulations to the finalists. I had fun in this challenge and learnt a lot from it. Let's behave like adults and provide unbiased and professional feedback to the finalists and if possible learn from them too. Cheers!
Vaclav Lhota over 4 years ago
Guys never mind. The jury might justify better their favourite designs, that's true. But they were probably busy and couldn't pay that much attention to this part (that's why they needed one week more, in my opinion:). Whatever is behind is actually not our bussines and it's not important. We all worked hard, learned new things, inspired each other and that's what counts. For the benefit of all!
Victor Production .com over 4 years ago
I am eager to see real official finalists.
Can anybody find drawbacks of my design ?
NASA (RASSOR) Bucket Drum Design Challenge with Design VPR 21
Thanks !
Aurelian Z over 4 years ago
Congratulations to all the finalists.
Since we have been asked for our opinion on the designs:
1. Some of these designs use flaps with hinges to block regolith from escaping. The revolute joint getting jammed with dust will not be their only failure mode.
Did you ever use a piece of cardboard to "jam" a cabinet door that won't stay closed?
Given the right rock size, these flaps will get stuck. Not at the hinge, but on the other sides, between the flap and the drum body. Living hinges not only do not help with this failure mode, but they might make it worse.
2. Another issue is with designs with an external helix that pushes regolith towards scoops at one end. These cannot work unless a large part of the helix edge is engaged at all times. If the 175 mm limit on scoop engagement is there for a functional reason, these designs won't do.
That leaves 4 designs that I see as functional and I would rank in this order:
- NASA Regolith Drum E3 by tommy.mueller-1
- Regolith Drum Cartridge Light Weight V2 by jason.homrighaus-1
- RASSOR Bucket Drum V3 by kyle.st.thomas-1
- RASSOR Bucket Drum by michael.r-32
With the exception of the 1st design, the fill rate claims are significantly exaggerated.
Dario D'Amico over 4 years ago
Well, congratulation to the finalist...
It's a bit disappointing that no solution with the rotating scoops and "fixed" bucket were considered since I think they are the best possible design. It's the only one that guarantees for sure a 100% fill ratio with basically no risk of the regolite jamming into it.
Several such solutions were presented with Vaclav Lhota even presenting a scaled prototype that looked to work pretty damn good.
https://grabcad.com/library/rassor_containermod-1
A bit disappointing but anyway...
My favourite entry amond the finalist is
Regolith Trap
Very simple mechanism.
Ankush Sharma over 4 years ago
Dario D'Amico Yes I think a re-evaluation should be carried out because there are many good entries, some even having working prototypes. The main aim of the competition was to have maximum fill ratio and many finalist entries have exaggerated and hypothetical fill ratios. I think Judges should give priority to the function and fulfillment of objectives of the challenge before fancy renders and stuff.
Victor Production .com over 4 years ago
I think VERY IMPORTANT is how much energy you are spending for collecting and unloading Regolith. You are in space, energy is very limited. Take a look on your design, like you are on the Moon !
Sava Savov over 4 years ago
@ Aurelian Z Yes, i agree with point 2. My first entry is exactly like these but then I developed it to something new - here is my version with external helices and it works really good - in simulation... I am sure that it is applicable for something here on Earth:) - I am pleased with myself. Watch this: https://www.youtube.com/watch?v=SM_IYEX9U7Y&feature=youtu.be
MiDesys over 4 years ago
@Ankush Sharma: max. fill ratio is important, but i think more important is max fill volume. Cause some designs have 90% fill ratio but low fill volume.
Yuriy Voloshkevych over 4 years ago
@RAHUL I totally agree with you! :( I have spend so much time on the simulation I have then make a great simulation but they have ignored it...
and I have do some calculations as well
Victor Production .com over 4 years ago
Please correct if I am wrong ?
Fill ratio = (Regolith volume * 100) / Max.dimension volume
RocketNut over 4 years ago
is the finalist list up yet?
Jason Homrighaus over 4 years ago
Why do so many people seem to think that a simple robust, highly efficient design somehow represents bad engineering or design? Why do they assume that having not posted a simulation means that the entrant made up the numbers or imagined their full ratios or results?
Repeatedly throughout the history of design and engineering, it is Often found that the most efficient, reliable and best suited approach to a problem tends to be relatively simple and to many they even seem obvious.
It’s disappointing to see people badmouthing designers, engineers and even our esteemed guests from one of the greatest engineering enterprises on the planet because they didn’t get selected.
People look at a simple entry without a lot of razzmatazz and for some reason assume it is simple and somehow not sophisticated. They do not see the many many hours spent after work tweaking and testing and prodding a design to see how far you can take it, how much it can handle.
Elegance in design and engineering is just as important and just as challenging as running simulations or generating renderings.
My design went through no less than 60 iterations from where it started. In the process it spun off 5 additional designs both simple and very complex. Each with their own benefits and drawbacks.
As to the finalists I think it is striking that many are fairly simple and robust. Funny that the keys to success for an unmanned lunar rover would be simplicity, robustness, light weight and reliability.
I think our esteemed guests from NASA are far more knowledgeable about what types of design challenges they have faced and what their engineering and mission goals are.
One of the oldest axioms in any professional undertaking is to give the customer what they want(and need). Not what you want or what you think they need.
Please show some respect, engage in the opportunity to learn and explore, offer your insight and seek insight from others.
Let’s show our guests why this platform is great and valuable so that there will be more opportunities in the future.
Tommy Mueller over 4 years ago
Jason Homrighaus +1
Divyakumar Patel over 4 years ago
True, I agree with you @Jason Homrighaus
Vishal Gandhele over 4 years ago
I think NASA knows what works best for those environments and I respect their decision. Congratulations to all the finalists and also to all the participants who learnt something new in the design process.
Victor Production .com over 4 years ago
Designs based on lift principle are more energy and time efficient than monocoque, so why GC is featuring monocoque and lift principle was left out ??
example of lift:
NASA (RASSOR) Bucket Drum Design Challenge with Design VPR 21
example of monocoque:
RASSOR Bucket Drum V3
Tapabrata Samanta over 4 years ago
I think the point NASA is trying to make here is sometimes it is better to go with a system which is more reliable, simple and robust with less probability of functional failure. And, the selected finalists have all these elements.
I think the guys who came up with non-obvious solutions have shown NASA what not to do. And, that is very important. Just think of the bigger the picture. We should collectively work towards helping NASA in arriving at a decision which would influence the success and failure of the mission. And, to do that we had to be willing to lose “the prize” by coming up with all those non-obvious solutions in an attempt to increase the fill-ratio in a way to find out that these won’t work and eliminate those non-obvious solutions from the list as quickly as possible and leaving behind the obvious ones which had the potential to work from the very beginning.
So, what I can see here is that, some of us chose to walk the obvious path and some chose to walk the non-obvious path. But, the aim of our individual journey was the same, that was to help NASA arrive at a decision. The very act of collectively participating in an effort to bring this mission to a success instead of trying to change our bank balance just by a few digits, in itself is a win! According to best of its knowledge, NASA has converged to those geometries which would actually work. We already won for now. Can’t you guys see it?
Ravi Maurya over 4 years ago
I would really appreciate if the respected judges have one final look at the idea of "static storage drum" design since it has highest filling ratio and storage capacity. There are more than 10 designs entries regarding that.
Jason Homrighaus over 4 years ago
Ravi while those designs do provide a high fill ratio they do not provide a high fill volume. The are very space inefficient devoting a lot of volume to the rotating assembly. The space where those scoops are represents nearly 1/2 of the available working volume for the design. The rotating assembly presents a lot of structural issues due to its need to have lots of buckets and open pass throughs. The design is also prone to catastrophic failure scenarios ie a small pebble could disable the entire drum. If the outer frame were to become bent, again total loss of function.
Lastly the mechanics required to actuate the drums would be massively difficult to maintain and prevent from becoming damaged due to dust.
Don’t get me wrong, bucket wheel excavators are very cool (which is what you are talking about) but the are maintence intensive and wear prone which are not great qualities for a lunar based machine
Jason Homrighaus over 4 years ago
Victor, how much energy is consumed by all the friction in the system? How will the friction change in the presence of abrasive lunar soil. What about the extra trips required to collect equivalent volume of regolith(full volume approximately half means 2x more trips which would be the most energy intensive part of the operation) what about the power budget. power on the moon is more or less free being solar based.
Jason Homrighaus over 4 years ago
Tapabrata Samanta Well said sir.
Vaclav Lhota over 4 years ago
Jason I fully admit your objectives. However, all this is valid rather for a high intensity working machine. On the Moon, the work load won't be that high so I think the main issue is just overall efficiency, energy consumption. Maybe none of our rotating shovels design is considerable and definitely deserve more study, but I still believe it's a very promising concept, considering its purpose, size, work load and location:) But again, I fully respect much higher reliability of a single drum bucket.
Vaclav Lhota over 4 years ago
Jason I was worried about the fricition, sure. But there was a big surprise for me, because it's not bad at all! I did some test with 1:3 and 1:6 models. And the filling? Yeah, you can actualy fill it to neraly 30 l. I think that's not bad either. I must say I really enjoyed the creative process and now I'm enjoying the discussion as well:))))
Jason Homrighaus over 4 years ago
Vaclav. I don’t disagree with your points either. As you know I played with that design for a while and 1 couldn’t come up with an improvement over what had been presented already and 2 couldn’t find a way to make it work well with superfine dust.
I really do like that approach. I also entered a design using a highly modified version of the same general concept(tried to combine the rotating scoops with high capacity drum). I spent like two weeks on it!)
Vaclav Lhota over 4 years ago
Well, in oposite, I was working on a drum with these traps and I didn’t believe the hinges will work in long term. And I also added a door, which will allow to empty in one turn!! Super simple and works amazing, tested on a 3dp 1:6 model. I could still upload the video. But you know what? I gave up with this guy and focused on that other concept. Evidently, I played a wrong card:D
Victor Production .com over 4 years ago
@ Jason. You are absolutely right lift designs with fixed drum and rotating scoops are little bit complicated in comparison to Monocoque.
Catch Regolith is in the same range like Monocoque design 25-30l.
But regarding productivity, fixed drum design is min 2-3x bether regarding saving Electricity and Time.
In reality fixed drum if it is build good, it will move min 2x more Regolith in same conditions.
So if you ware a mission commander which Rassor would you take: "bike" or "superbike" ?
Take look and prove me wrong, I would be Really grateful, thanks in advance.
Example of lift:
NASA (RASSOR) Bucket Drum Design Challenge with Design VPR 21
example of monocoque:
RASSOR Bucket Drum V3
All the best
Yuriy Voloshkevych over 4 years ago
why sprial drums aren't good ?
Jason Homrighaus over 4 years ago
Victor. I did look and I like the concept as I stated before. I would like to better understand where you are coming up with your energy consumption estimates. 2x efficiency in the real world is way way way beyond Bike/superbike comparison. That is a very tall claim. In many processes efficiency increases of 5-10% are really good and you are claiming 100% or more. Can you share how you arrived at those conclusions I’m very curious
Vaclav Lhota over 4 years ago
Spiral drums are good and hell reliable. They only can't get rid of bigger rocks, if they collect some. Especially in designs with longer narrow, curvy sections. And then, in long term, as you collect more and more, you increase the risk some will stuck and then you know what's gonna happen:)
Yuriy Voloshkevych over 4 years ago
oh yeah i know... thats why they probably dont take mine... :)
Ravi Maurya over 4 years ago
Jason Homrighaus, You're wrong about the high volume ratio. Designs with static storage drums provides highest regolith capacity. If designed carefully with all practical data it can stored upto 40 liters. Even the design I submitted has a capacity of 31 liters. Which I guess hardly 4-5 other designs have. About getting damaged by dust - its gonna be the same as in case of orignal RASSOR 1.0 and 2.0. If those designs can sustain it so as other. If you're worried about getting dust in the mechanism than the designs that have trapping door mechanism won't last for a minute at moon's surface. I do get the structural part that it might not be as strong as compared to monocoque designs but there are ways to prevent that. Some of the designs have taken that into consideration too.
Victor Production .com over 4 years ago
@ Jason. Friend, in short, on a just one feature, and if you look closely, but it have more ... : (for example, same conditions)
Lift designs, have 40 revolution for loading and 0.5 to unload, that is 40.5 revolution
NASA (RASSOR) Bucket Drum Design Challenge with Design VPR 21
Monocoque designs, have 40 revolution for loading and 40 to unload that is 80 revolution
RASSOR Bucket Drum V3
If you put that on Moon surface, you will have almost double productivity, minimum ...
All the best
Sava Savov over 4 years ago
@Yuriy, now as I look at your simulation it can be seen that there are some problems with spiral drums. It looks that in the process of digging they can be filled enough but while digging they throw back some of the regolith which they just have been taken. And it is not clear how much regolith they can hold after the filling is finished and when the car start moving to the unloading depot. I too made some tries with spiral for my drum and saw its behavior. Didn't liked it much and that's why I started to look for another solution.
Paul Kyum Lee over 4 years ago
Victor:
But my monocoque design : NASA RASSOR Drum Design
can fill in 6 rotations and empty in 5. That is just 11 rotations total. I think the issue of monocoque and lift designs are case specific, some designs will be better than others.
Congrats to finalists!
Jason Homrighaus over 4 years ago
Ravi. 3 of my monocoque designs match or exceed that volume. And that assumes they only achieve an 80% fill ratio in the containers. 32l,33l and 36l respectively
This is the same for numerous other designs. There are two main types of monocoque drums that I saw. The ones that use baffling with multiple scoops per volume and those that use single scoops per volume. The multiple/volume style(of which the NASA rassor drum is one) suffer from the nature of the material. In general they are limited to around a 50-60% fill ratio because the material will leak out through at least one of the openings.
The second style of single opening per cavity (of which there are several in the finalists) offer the greatest potential fill ratios albeit at a slower fill rate. The key is that the great majority of the material that they capture is positively contained within the volume until released. Additionally they can make maximum use of the available 52liters of the defined volume compared to any other designs.
I in particular really like the helix style drums as I really think they can pack the greatest volume. I fiddled with them but kept trying to have an open middle but I didn’t try the approach used by some of the finalists and realize now that that was the way to go for maximal potential.
As some have pointed out some of the monocoque designs utilize very narrow channels which I think is risky. That is part of why I continued to maintain a relatively large oversized intake that can only actually cut about 1/3 of its opening. This is due to the shape of the other cartridges limiting the depth of cut.
Honestly the engineering challenges of this application are pretty intense and every drum concept is a compromise No matter how simple or complex.
Jason Homrighaus over 4 years ago
Victor, in ideal conditions and assuming your monocoque design fills at the same depth of cut as it unloads. A lot of the monocoque designs have oversized intakes and as such will unload faster than they load so maybe you will see 30% improvement with a bucket wheel.
But now you have to consider the other factors, first off is weight. Monocoques can easily weigh 1/3 what a bucket wheel system can.with a cost per KG to the moon of well over 1 million you can bet your life that weight is a major influencing factor in these designs. Second is reliability, what is the long term viability of a bucket wheel mechanism in a highly abrasive environment? No one really knows for sure but we can pretty reliably that a monocoque with no moving parts has a near 100% reliability
Ravi Maurya over 4 years ago
I give up. Not going to explain any more. But again as I said earlier, It would be an honor if the Judges of "RASSOR Bucket Drum Design Challenge" give another thought of considering other designs. People are expecting a lot of great work from NASA. I would personally never want a great design submission go unnoticed that might just change future on moon. So I request the jury to take quality time and have a one last look on entries.
Thank You
Victor Production .com over 4 years ago
@ Jason. With all do respect, we in engineering don't gamble with "maybe you will see 30% improvement" You are right that Monocoque without moving parts is by definition more reliable in comparison to lift, but if you compare those systems over operational time, bigger rocks can ruined Monocoque and lift will remain operational. Remember, we have rocks in all sizes.
Test it, and see what numbers will going to say:
Lift designs example:
NASA (RASSOR) Bucket Drum Design Challenge with Design VPR 21
Monocoque designs example:
RASSOR Bucket Drum V3
All the best
Sava Savov over 4 years ago
About the entries with outer and inner helices: I started with this concept from the very beginning and can say something about them. It is much better the inner helices not to be as huge - they must be narrow bands mounted on the inside diameter of the drum cylinder. That increases the fill ratio - I tried it. When the inner helices are like they are now, there comes an unexpected effect of obstruction the filling. And I have a feeling that it is not good the outer helices to make more than one turnover around the drum cylinder because the drum moves in radial direction ...? but i may be wrong in that - not sure.
Jason Homrighaus over 4 years ago
Victor when I said maybe 30% I was saying that if it takes 1/3 the revolutions to unload then load then the rough calculation would be a 30% improvement using a fixed drum rather than 100% you claim. It’s not a gamble it’s simple math.
Dominik Höber over 4 years ago
@sava: i agree with your opinion on the throw back of regolith by inner helixs, but as you can see on the double helix drum by stephan weissenbock, there is used a kind of lock to prevent this.
Jason Homrighaus over 4 years ago
Victor. I would also note your assertion that a lift system is somehow immune to a large rock issues is disingenuous they are just as susceptible however there is a greater risk in that if the bucket system jams, (ie rock stuck between drum and scoop) the entire drum is rendered useless. If a channel in a monocoque gets a rock jammed in a scoop, there are other scoops and even with a rock jam, the monocoque intake can continue to injest material albeit at a slower rate.
Vaclav Lhota over 4 years ago
Bucket system can't jam by a large rock as there is small space between these two surfaces. These two surfaces move separately in different directions and the only thing that threatens them are small fragments that have exactly the size of the gap between the two surfaces:) But this can be overcome by sufficient torque while minimizing contact surfaces. There is just no way how to block the shovel entry. You can scratch it, damage any other parts of course (as any other monocoque body) but you can't jam it that easily by larger rocks.
Sava Savov over 4 years ago
I am starting thinking that main reason they did not choose any of the solutions with the rotating scoops and "fixed" bucket is that the arms of RASSOR can take a lot of crooked positions?
http://prntscr.com/s9ttph
https://www.researchgate.net/publication/261248231_Regolith_Advanced_Surface_Systems_Operations_Robot_RASSOR
Raul Santos over 4 years ago
Congratulations to the finalists, I am sad to not be able to reach the final, but happy to participate, I would like to receive some feedback on my designs, this was my first challenge and unlike the finalists my projects are simple with divided chambers. I invite everyone in the community to send me feedback on what could be improved or what could be done differently, it will be very important for me to receive any message!
Sava Savov over 4 years ago
I looked at your last design.I highly doubt that with this geometry the drum can fill 70%. I made some simulations with simmilar geometry and I think I know what will happen - after the first revolutions, when the fill ratio reach, let's say 30%, the regolith inside will start to fall right behind the opening and will start to make the filling process difficult. That will lead to a situation in which some of just captured from the scoop regolith will be thrown back outside. Maybe the fill ratio can reach more than 50% but this throwback...- is something like tango -"two forward one back" . But you made a simulation - isn't it shows the things as I descripted it?
MiDesys over 4 years ago
About stones and rocks. One way prior collecting regolith is to send destoning machine wich will separate and collect all stones and rocks from regolith. After regolith is cleaned, RASSOR can be send to collect it.
Vaclav Lhota over 4 years ago
I was thinking of a simple, lightweight plow or a rake, mounted on RASSOR
Raul Santos over 4 years ago
thanks :) @Sava Savov, how did you calculate the fill rate?
Sava Savov over 4 years ago
I think that more important is the volume that must be captured and it must be more than 17,6 liters. The required fill ratio is given more for orientation because for the given outer dimensions can be assumed that the internal volume will be around 35 liters. So if we fill the internal volume of the drum more than 50%, we will probably get more then 17,6 liters regolith.
But if the drum has internal volume 45 litters a smaller fill ratio will do the job ( 44% fill ratio will be enough).
I personally made my drum with 35 liters internal volume and in simulations I "calculate" the fill ratio just by watching - it can be seen if the drum is filled more or less than a half.
BTW it is very important to do the simulations with granules that are more close to the size of the bulk material. For example I made my simulations with 20 mm diameter balls and I had a lot problems until I find a shape for the drum that can collect some more than 50% of its internal volume. But then one of the participants here (it seems he deleted his profile after announcing the finalists) made a new simulation with my drum and with smaller balls - 8 mm diameter. The result was dramatically better - I think that the fill ratio become 100%. It seems the centrifugal forces play a big role when filling - when the mass of a single granule (ball) is smaller, the influence of centrifugal forces decreases.
You can see here one and the same drum but how different the fill ratio is with 20 mm balls and with 8 mm balls (20 rpm).
With 20 mm balls:https://www.youtube.com/watch?v=E2oC0B5MYG8&feature=emb_logo
With 8 mm balls: https://www.youtube.com/watch?v=DQ-GpTodRec&feature=youtu.be
Victor Production .com over 4 years ago
We all, are making a profit from this, in one way or another, besides nothing's over, until it is over ! :) All the best to all !
Vaclav Lhota over 4 years ago
Ktan this is hell crazy!:D Write a book about it
Sava Savov over 4 years ago
I know what Ktan1 is talking abouot - about the so called "spec work". https://youtu.be/DsstOs-K7gk
Filip Šabacký over 4 years ago
Hi to jury team (Brad, Andrew, Drew, Jason) - why there is no entry in the finalist list with not rotating inner drum? - for example this one:
Regolith Advanced Collector (RAC)
I think this idea should be there...
Sunoj Kashyap over 4 years ago
Congratulation for every one, I feel people who put their personal time and submitted designs, At least they should get some badges or something in Grabcad , now its like We done something for nothing
Stephan Weißenböck over 4 years ago
We conducted more tests and simulations with small improvements, as already proposed in the description, and can conclude, that the fill ratio of new test simulations increased significantly to up to 90% or more.
Elie VILLAIN over 4 years ago
Happy to be among the finalists! Again, I would like to thank GrabCad and the LSII for organizing such an interesting challenge. It was a real pleasure to participate; I worked a lot and learned a lot, especially whith the simulations. A lot of fun ! May the best win :)
Trevor Owens over 4 years ago
I think everyone did a good job, just the finalists put their time to create amazing! designs and simulations and deserved to be a finalist. GOOD JOB whether you are a finalist or not you all gained experience doing this so at least it's not all for nothing :D
Yes, there were many good designs, including all of yours, but there were 352 designs and only 10 of those were chosen, so I think the judges did their best to decide, looking at all of the specs and their time too, so we could give them some credit for it.
Sava Savov over 4 years ago
Elie, your solution is really genius! I like it very much! Although
in fact, almost the same result can be reached without any moving parts or mechanism.
Kesa over 4 years ago
Hello Everyone,
I have been seeing a lot of negative comments as of late on this challenge. The judges have made their decision based on these individuals being experts in their field. We understand that some may feel frustrated that their design and hard work were not selected but all decisions are final. Please show good sportsmanship and that GrabCAD is a place of learning & creating, full of great community members.
Best,
Kesa
GrabCAD Community Manager
Vaclav Lhota over 4 years ago
Well, thumbs up for detailed feedback Luděk!!
Sava Savov over 4 years ago
So, who is the best, Ludek?
Jason Homrighaus over 4 years ago
I have provided some comments related to Ludek's study. I would classify it as poorly executed and poorly designed at best. Please take a look at the study and the comments and perhaps provide some commentary.
Jason Homrighaus over 4 years ago
Added some updated simulations on my entry. Obviously too late for judging but Ive been working hard to get accurate behavior related to friction between the drum and the particles. Most recent sim behaves similarly to some of the real world models with larger particles. Still working to simulate Static Clumping that is discussed in some of the research. The angle of repose as the drum fills seems to match some of the data on regolith simulants. Once I get the model finalized I may try some of the other drum designs to see how they work. though Im not sure how to properly simulate some of the moving components in Houdini.
Jason Homrighaus over 4 years ago
From what I have been seeing, the depth of the cut is a critical factor for how different designs behave. Its seems that the magic number falls in the 30% to 50% of the intake opening. This prevents clogging of the intake charge in the chute and allows the material to slide properly. Speed of rotation seems to be a lesser concern as long as the cut depth is not too deep. It also appears that a variable rate of feed/rotation may be beneficial as the drums near capacity it may be beneficial to slow the rotation and reduce depth to allow the material more time to settle. It seems like once the fill reaches a cresting wave flow things start jamming up hard which is what I think we were seeing in Ludek's study.
Jason Homrighaus over 4 years ago
http://grainflow-dynamics.com/index_files/GM_Walton_et_al_Effects_of_Gravity_Cohesive_Powders_2007.pdf
This is a really interesting paper that I wish I had found a month ago which discusses the topic of powder and grain behavior in rotting drums(specifically with a focus on Lunar Regolith handling). Offers some great insight into various aspects and considerations that impact the movement and fillability of a drum as we are all looking at them. In particular the cresting behavior is something I witnessed in a number of the simulations I ran and may indicate the benefit of friction reducing coatings on the inside of the collection drums to reduce the sliding friction of the granules within the drum, if they can be kept from rotating and cresting the fill ratios become much much higher.
Caleb Clausing over 4 years ago
I like the simulations, and that paper is interesting. The way that the material moves inside the drum is important for my design, so it's cool to see how much research has already been done. Although the paper also mentions a ton of challenges too that I didn't even realize. It would be cool if there was a simple way to test a physical model in an environment that was close-ish to the lunar environment because like you mentioned, moving parts are hard to work with in simulations. But thanks for sharing!
Luděk Čechura, LC - machinedesign over 4 years ago
Thumbs up - Jason Homringhaus !!!!!!
Luděk Čechura, LC - machinedesign over 4 years ago
PS. You are on the right path, if you put a small space in your ego head, there will be a huge space for thinking. Big things are waiting for you. I wish you a good trip! Ludek
Jason Homrighaus over 4 years ago
Ludek, thanks for the Kudos but I would like to point out that the simulation seems to refute some of what your study showed but this is a good thing. IT shows us that there is a lot more going on here and this is how the process is supposed to work, find a stumbling block, seek to understand, work the problem and define better performance. sometimes through physical changes and others through operational changes.
the drums do seem to fill properly to capacity if properly loaded as far as feed and speed. A broader evaluation of any design would be warranted to determine the best feed rate and cut depth for any given design, it is not just a question of raw rate a loading or speed of discharge.
Luděk Čechura, LC - machinedesign over 4 years ago
Yes, the test is not a laboratory output. It only has to verify the basic function of the design. It is to show that theory and practice are sometimes far apart. The output can be - a reason for further reflection. Sometimes the problem is bigger than it is at first glance. I think it's good to show it physically, rather than debating theoretically for a long time.
Kesa over 4 years ago
WInners will be annouced soon
Stephan Weißenböck over 4 years ago
Congratulations to all! And special thanks to NASA for offering this opportunity and including our design in the top 5.
Clix over 4 years ago
I would like to thank for the opportunity to be again in the world of ideas to NASA and GRABCAD, i consider contests a inspirational way of view things an an opportunity to meet special people, so nice to meet you guys! can wait to see your work next time :)
Sava Savov over 4 years ago
Congratulations, Clix! You passed the last line :). All good to all, till next time.
Michael R over 4 years ago
What an awesome challenge! Thank you NASA and GRABCAD for making it possible for so many people to contribute their efforts and ideas towards a mission this profound. It has been an inspiring opportunity and an incredible learning experience. Congratulations to everyone!
MiDesys over 4 years ago
Congratulations to all! I think we all learned a lot from this challenge. It's very glad for me to see that first three places go to USA although there where better submissions.
Elie VILLAIN over 4 years ago
Congratulations to all the winners ! :)
Kyle St.Thomas over 4 years ago
I want to extendHUGE thank you to the NASA team working on RASSOR, thank you for allowing us as a community to have a small part in helping develop the future of space development. I look forward to following your work on the rover as you refine it in the coming months and years, and congratulations to all the other finalists in this competition. :D
V.Novacov over 4 years ago
The all chalanges is a a big boolshits.Еverything is set up.
geo over 3 years ago
The drum solution is the wrong way to go.
A lightweight drum and stones in a rough environment will not do well. Toy sand for testing is wrong.
My solution has a safe overload protection, with a much higher loading capacity at the same time.
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