Saturday, December 16, 2017

Hobby servo accuracy is poor

I have been thinking of building a pan/tilt mount for the probe, at least for the road testing to allow me to program "sweeps" through different AoA/yaw combinations. Pan/tilt servo mounts are pretty common, using hardware like this one, so I figured I'd give them a try.

I purchased a Hitec D645MW servo and a Pololu 6-channel Micro Mastro USB controller and tried them out. Using the published conversion factors for the servo, I tried commanding it to 30 degrees and 60 degrees, based on the book conversion between PWM pulse width and output angle (0.08 degrees per microsecond). Here are the results below. Clearly the conclusion is that "out of box" accuracy for hobby servos, even this relatively nice one, is not to be expected.

I'm upgrading to Dynamixel AX-12A actuators and will publish my results.




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