Testing a Jumping Robot Leg with Elastic Tendon | James Bruton
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- Опубліковано 20 січ 2019
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While I'm waiting for openDog parts to arrive, I decided to build a test rig to experiment with a robot leg that has an elastic tendon. I can make the leg comply with force, or drive force between the motor and the actual leg position.
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Former toy designer, current UA-cam maker and general robotics, electrical and mechanical engineer, I’m a fan of doing it yourself and innovation by trial and error. My channel is where I share some of my useful and not-so-useful inventions, designs and maker advice. Iron Man is my go-to cosplay, and 3D printing can solve most issues - broken bolts, missing parts, world hunger, you name it.
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Should I build a 3-legged tripod robot with legs like this?
James Bruton Yes! OpenThreeLeggedLamb all the way
Please do it fast ,but stability?
spider bodied robot maybe?
i was thinking a cheetah.
Try for a two legged one
You didnt mention it directly, but the music proves that somehow you are going to summon the Devil with this leg.
Beezqp 🤣🤣
Watching this while being drunk is so good you get excited and surprised for simple things...
Very interesting design! That leg design seems to have very promising possibilities! Keep up the excellent research!!
MIT one legged hopping machine, 1980's , I requested the paper whilst studying physics in 1990 and was delivered a lovely paper copy. Great channel. love your work.
Great video! And what an epic music!
Oustanding work, robotics are always interesting. They help you learn stuff and work on new solutions
Ideally you should be able to model tendons in opendog without changing to springy bits - tendons are basically a spring F=kx. However a spring reacts instantly and can reach very high speeds - the motor drive screws are relatively slow so they could behave like a spring but only at a very low frequency. With the three legged doovie ( yes please build it :) ) you can replace the bungie with a stiffer tendon effectively doing the high frequency movements, and model the low frequency springiness in the motor drive code - if that makes sense James?
You have turned yourself into a legend of robot building mate! Well done.
Awesome video
Great to hear some updates about OpenDog
I’ve been worried about that little yellow fellow 🐶
It's happening, I just need to make sure the videos have something interesting in them
Love your projects... I wish I could do it...
Dude, one of these days you're gonna get everything all figured out and its going to be amazing.
Try meshing both the rigid and the organic leg design so you can get something that responds fast and absorb the impact. You could give a rigid leg an adjustable suspension on the lower leg.
Interesting video. You could make a much lighter weight version but just as powerful if you used single extrusions over the double ones, then used flat elastic which you wrap around the motor instead of a pulley.
I am always your fan!
Awesome. If you do apply it to a quadraped keep in mind that an animals spine plays a big part in its ability to run fast, so making that flexible (even passively elastic) would be an advantage. Also as the control gets more complicated, have you looked at neural networks or evolutionary algorithms in order to find efficient walking gaits?
Good stuff boss
You are awesome James
The creative stuff, this is what the internet was created for!
you can also use a velocity sensor to determine the downward force. preimpact
Wow, so happy to see the elusive O-Drive in the wilds.
There are six in my openDog project!
Very nice
Another option that's been used in a number of compliant walking machines is to use a spring to extend the leg and the motor, via an inelastic tendon to bend the leg. (Look up ASLP Walking machines). If you end up with antagonistic 'muscles' you may as well program the motor to behave as a spring damper - closed loop torque control.
In terms of making it walk, you can use something very similar to the sequencer commonly used in IK, except you are delivering a sequence of torques (Forces) rather than positions. This approach makes it self adapt to obstacles / terrain without the need for AI or complicated localisation.
I lolled quite a bit when you said you made your robotic dog jump in the air by accident!
I gotta say that’s the most intense leg assembly montage I’ve ever seen.
wow nice your the best
You are Amazing ! 👍😉
Maybe you could use the pressure sensors on the feet of open dog to pull the legs back in when its feels a force acter jumping to dampen it.
Epic Music!
Have you thought about building a robotic camera jig, for some more dynamic shots? It could be a cool project.
would be interesting if you could use the dual extruder printer to make air muscles with flexible and ridge plastic.
I've been wondering what kind of 3D filament do you use for those parts PLA, ABS, PETG;...???
Thanks for the answer!
Love the dramatic dark music during the build time lapse. Reminds me of the music of Invader Zim. You would live that show. Ever seen it?
This is a really cool channel! Subbed! Have you ever considered designing and making prosthetics? I've always wanted to try to design an arm, as my father only has one. I had classes on programming, solid works, electronics and pneumatics in college, but still not sure where to start.
Wao I love this
where did you get your lathe, im looking into buying one and the one you have looks like a good desktop size
Sick
If you only used a tendon from the back of the knee to the extended rear heel and a motor to replace the quadricep and control movement and tension the elastic tendon, could that work?
I recently got my own 3d printer ... seeing those parts makes me think this mist have taken absoulute ages!
Agreed. He's got a few printers, but even then with all of them running on just this one project I have to assume a few days.
I've got a 3d printer, and have been thinking of ordering some 2020 extrusion for building things with printed ends. Seeing this has inspired me to go ahead and just hit aliexpress and order in bulk.
That said, I wonder where James gets all his.
@@nothanks7752 ya throw that wallet into the fire, in the name of creavitity and innovation!
Bravo!
Encore! Encore!
What about adding a foot? You would be able to measure load after jump and then adjust knee motion to absorb fall kinetic energy.
Very interesting.
Which encoder are you using?
nice. but my question is where you show the graph at @8:30 of the leg position. it might make more sense if you reverse the pot so that when the leg is extended the value is high. I know it doesn't make that much difference as long as you know which way round, but if you're looking at graphs of the position. personally it makes more sense if when it's extended the value is high :D
looks different, a tri legged robot would have to move in an interesting way I think, I'll keep an eye out for future devolopments (though I'm falling behind, with my work super busy for the next few months.)
Bruce Neely tell me about it. I haven’t released a video in months and I haven’t been keeping up with my fave youtubers anywhere near as well as I used to.
@@AcrimoniousMirth well, I've never posted a video. Maybe some day. My budy period will run until April 15, then I can catch up.
Epic music guarantees success 💪
What is that lathe could you provide a link or something to it or just the name???
Hmm, over on the wearable electronics/soft circuits side of things, they have conductive stretch sensors. So it may be possible to turn the stretch into a known value?
Yes possibly, knowing the actual joint angle is critical though
Hi, have you considered using FPGAs for the kinnematic models? That should increase the performance for complex operations dramatically...
Question1: it seams like compliance is kicking in a bit late. is that normal?
Question2: how can elasticity be quantified? you used elastic cord which has a set of characteristics, but other methods might be more suited for a robot, like a winding string rolling and unrolling a steel cord connected to a motor.
Could you post the CAD or STL drawings?
I have been watching since 50k subs
thanks!
hey, can anyone say to me name of application that he used to designed on his video, thanks.
Go for it, make open dog compliant. Run the kinematic model on an overclocked laptop!
İnspring as always
Any plans to use SAMD microcontroller Arduino clones? They're *much* faster than traditional Arduino micros, so they might be a good candidate for the faster sample rates you need?
Doesn't the Odrive have a torque command mode? That should allow you to move the compliance into the motor (and use the attached encoder to measure it) rather than adding a much less controlled spring. Granted it wouldn't give you the benefits of energy recovery in a run cycle, but it should make it much easier to build the dynamics model (in terms of torque and velocity of the actuated degrees of freedom). The excellent MIT OCW 6.832 course on underactuated robotics has a lot of stuff relevant to this from what I remember.
Where wer u this days Bru.. ❤
Is this gunna be like the salto-1P robot
Last time I was thinking about modeling a robot dog and then you started OpenDog. This weekend I made a simulated hopping robot in PyBullet and yes you are starting a jumping robot. That's really nice! (BTW search my name on UA-cam if you like to have a look)
Make a Robot Bambi please :D Nice concept!
It'd be awesome to see you make a cycloydal gearbox for the motor. It'd not be back drivable but would gear you down.
What material are u using to make 3d printed parts ?
How many 3d printer du you got?
What program did you use in this video?
Rotate the leg around when attached to the table
I think this would help it hop a lot better!
have you seen the synthetic muscle filament? you should use that if you can get it
I don't think it'll be fast enough
or fast movements
niceee
where can i learn robotic like you? is it possible online?
Lol that Epic music
Do you know what is the music at 2:00? Shazaming did not give me any results.
are these projects documented anywhere?
Which program did you use for those models ??
I probably won't get an answer anymore but why are you using the turnigy motors and not the odrive motor? To my understanding the odrive motor has better specs and I'm looking forward to buying one so please tell me if you know something!!! :)
I think if y get range of motion little bigger y may get it jump better. Would putting gearing to the joints and driving it from each joint give more speed and torque to make it jump better.
I like the music
thanks!
According the music; this robot is build for raiding Mordor.
How was opendog?
Do you know how crossbows work? could make a robotic flea...
I enjoy the new music
What software are you actively graphing the data of the rotary encoder from your Arduino?
The Arduino IDE Serial Plotter
James, perhaps you could build the alien from predator but mabe start with the helmet? add some fancy gizmos to it and such.
why use bearings instead of bushings?
What motor are you using?
Can't you build a release mechnism, so you stretch the bungee and then release?
Well the motor moves pretty quick
If you get this to work with 3 legs, maybee you can create the droideka from star wars (the one that rolls), just a thought.
Attach motor to some spring stilt boots and see how high you can go - would be scary.
I maybe over simplifying this but could you not program open dog so that if it jumps and it's legs are fully extended, when it hits the floor it shortens to match (or slightly faster than) the acceleration of the body due to gravity to take out most of the force of the landing
Yes, it could do that with foot sensors, but it needs pretty quick processing to do everything in real time, instead of catching up the bungee afterwards
Well, you made a human and a dog... why not a rabbit this time?
That'd be awesome
Rabbit could be a little small. I say kangaroo
@@matthewcollier3482 well, open dog doesn't look to scale either
Ed...ward...
Or better... A giant FROG!
Berzinga!
Top
The three legged robot idea has me envisioning the hunters from half-life two episode two.
Two oposed spring are minimal, like muscles. Also brushless motors are bad at low revolutions, you should use gearring of some type.
yep - it's only a test
James Bruton, little suggestion to test))
Two parallel ropes when twisting around each other became shorter. It can be used as muscle. Can you try? Just motor, hook on a shaft, hook on base and something to measure force. Thanks.
Why does the robot need to weigh itself in each leg if you could just use an accelerometer to work out weight distribution unless you’re going to have home something else moving on its back which doesn’t like sharp stops so you’re basically also using this system as a suspension for a walking table taking delicate objects around.
Where do you get your encoders? I’m building a humanoid robot on my channel and I’m going to convert my motors to motors with encoders attached but I’ve noticed in your videos , that you have encoders fitted around the shaft , ide be honored to know what kind you use so I can save money lol
From the ODrive website
James Bruton thank you so much sir!
Hi can you make mach x 4
You should do a joint project (pun not intended) with an AI designer. Specifically the ones making ai learn to walk in software.
How on earth do you prototype so FAST? Its amazing! You just made a large sized Salto, which a university spent years making, in a couple of weeks. It would take me months and months to do what you seem to be able to complete in a fraction of the time. Do you have a technique? Minions? Elves? Can I ... can I borrow some? : ) Also, have you read Marc Raibert's "Legged Robots That Balance" (the book as opposed to the article)? He details the MIT one legged jumping robot and its control system, you might get a kick out of it! (no pun intended. Well, sort of)
Lots of 3D printers and experience building things that work every week ;-)
@@jamesbruton Incredible :) I could do with another 3d printer to be honest. I would also love a Tormach PCNC. Still, you getting the CAD and maths done quickly, and right, in that time is still impressive. Whoever you used to design toys for is surely very sad to lose you!
Why not use the motor as the compliant part?
Because the motor can be back-driven and itself provides a holding force it can remove the need for a stretchable cord.
It will make the motor being externally turned an asset rather than something you have to combat, and depending on the mechanical configuration it will allow for both compression and tension.
As an analogy with this setup it would be the muscle that is compliant not the tendon.
@@UnidudeNine Good point, I've only had experience controlling motors in this way using a Virtex FPGA (~100,000Hz).
I do wonder however if using a PID control configured to recover the position more slowly could alleviate some of the issue of using a slower update frequency. (Not great for rapid motions but might help in a situation like this)
what's the name of the motor and driver you're using?
They are ODrive 3.5 drivers with Turnigy 149Kv SK3 6374 motors
What happened to the punching robot arm?
Try using rubber tubing instead of the bungie cord.
make some that you can fix to some boots and wear