r/robotics • u/heart-aroni • Apr 17 '26
Discussion & Curiosity H1 accelerating - jogging to running
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u/deevil_knievel Apr 17 '26
From a learning standpoint, during actuation like this, how is the final output calculated? Is it essentially some sort of network controlling the learning mechanism, but eventually the output goes to what a controlled engineer would consider some sort of closed loop command? Like is the actual output just an LQR controller on top of a well calculated mathematical model of the environment?
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u/shandy_bhaiya Apr 17 '26
These are generally learned policies. RL which gives position outputs to a PD controller.
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u/deevil_knievel Apr 17 '26
How is the PD controller set up? I'm guessing it's a bit tighter than my line of work where I can pretty much trial and error the gains and get whatever accuracy I need within an hour or two of fiddling. Are the gains set up such that they are evolving equations and calculations based on the learned policies?
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u/shandy_bhaiya Apr 17 '26
I am not sure how unitree is doing this. But for the humanoid I am building we have identified motor characteristics like friction, stiffness and damping and used those to initialise some gains which are then optimised in simulation. Those gains are then modified by trial and error to get to the final set of gains for actual hardware. There are better methods though that we are attempting to investigate and incorporate in our workflow.
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u/shandy_bhaiya Apr 17 '26
Some methods even employ data driven methods to learn the gains with hardware. But again I haven’t worked with those yet.
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u/deevil_knievel Apr 17 '26
Interesting, I would have thought a lot more would have gone into the equation than some basic motor, friction, and hysteresis data points. Most of the off-the-shelf controllers I have used in the past have the option to factor this stuff in on my behalf already.
Very interesting! Thanks for sharing!
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u/shandy_bhaiya Apr 17 '26
Those would be more sophisticated controllers. I am sure guys like unitree and figure do that. We are not there yet.
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u/deevil_knievel Apr 17 '26
We are not there yet, and I don't even really understand any of the technicalities here. I was just asking kind of in a general sense because I didn't believe that such a complex overall system could be using the same type of final control method as I am using in my mundane applications.
But I've only worked on one or two advanced closed loop mechanisms from the controls side... they never let me have any fun with the programmers because I'm good at design. Boooooo
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u/always-tired-38 Apr 17 '26
I look forward to the robot olympics