High Frequency Vibration/Simulation Inaccuracy #1927
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jack33001
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Hello,
I'm developing a controller for a quadruped for my masters thesis, and I'm having some issues with simulation accuracy and contact forces. In the following video, all the actuators are controlled with simple PD control with a constant position setpoint (the video is at half speed):
vibration.mp4
The corresponding plot of joint forces for this video looks like this (the actuators are set to saturate at +-8):
The problem goes away if I set the PD controller gains very low, or if I set the motor interias to be an order of magnitude higher than manufacturer spec; neither of these solutions are feasible, as they make the robot's dynamics far too slow for what I am doing (and far slower than our real-life hardware). Decreasing the timestep doesn't solve the problem either. This makes me think I have a fundamental misunderstanding of how best to be doing closed-loop control with MuJoCo's actuators. I need to be able to alternate between position control and torque control on these actuators, so I'm using the "motor" actuator type, and have a PD layer that can work with either force or position feedback. Is this best practice? I'll include my .mjb config, in case the problem is there instead. Thank you for the help.
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