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chip updates: better standing ideas - this time featuring mini-cheetah [updates]

So yesterday when we were testing our chip, we noticed that while the robot was standing, there will still other issue with the robot that needed fixing, i.e. to stand we needed to have some more optimal angles for the legs.



So looking at MIT Mini Cheetah, we might have some angles that we can use to at least try out the standing. Here's an image of Mini Cheetah standing.


So the other thing we decided at like 2am, was that for walking and dynamics, we probably want to go with an asymmetrical leg setup like Cheetah 3 and Mini Cheetah. If this is the case, we want to probably try testing the standing on the angles we see in this photo (at least the eyeballed angles).


So here's the plan for the night: The first thing we're going to do is change the PID Velocity Control to PID Position Control because the steady state error in Velocity control means the legs drift right? Non-zero velocity at steady state. But in position the steady state does not matter we'll only be a bit off for now.


Ronak's updating the PID Velocity to PID Position with the same gains. I'm working on setting the leg angles and etc.


test B1: trying new leg angles AND PID Position control

So for this test, we change the velocity to position command, and the front and rear leg angles have been changed from yesterday.



In conclusion, this test seemed to work pretty well! We just need to change the rear leg angles for standing.


test B2: trying different leg angles for the rear legs

Okay so for this test, the only thing we changed is the rear leg angles into something that looks like it will stand a lot better.



So this one kind of slipped as well - we're going to up the P from 0.001 to 0.005


test B3: trying the standing with the same leg angles as last time and higher PID gain

We're trying a gain of 0.005 this time.



Same conclusion, we need more P.


test B4: trying the standing with the DIFFERENT leg angles as last time and higher PID gain

We're trying a gain of 0.01 this time. And different leg angles.



In conclusion, we're upping the P-gain again and moving the leg angles a bit again. Just the front leg angles though.


test B5: trying the standing with the DIFFERENT leg angles as last time and higher PID gain

We're trying a gain of 0.05 this time. And different leg angles.



In conclusion, the 0.05 P-gain, and the following leg angles work. Our current draw is 700Ma.

P-Gain: 0.05

I-Gain: 0

D-Gain: 0

Current Draw Total: 700Ma

Power Supply Voltage: 23.8V

Forward Leg Angles:



Rear Leg Angles:



And that's a wrap for today. It's bedtime.


#chip #updates #mini_cheetah #angles #standing #testing

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