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I have a kuka iiwa (7 joint robot arm). Attached to it is a circular aluminum platter with a steel ball on it. The goal of the project (for giggles/ challenge) was to use the internal torque sensors of the robot in order to balance the ball in the middle of the platter. Due to the fact that I was unable/ not allowed to use FRI (fast robot interface) whereby I can control the robot from C at about 3ms feedback loop, I can only update the robot position at about 4Hz... My quick and dirty solution consisted of the following:

Measure the torque on the final two axes of the arm and apply a mapping to generate the ball's position (filtration and hysteresis were well implemented to improve the data quality). If the ball velocity was sufficiently stable, generate a motion that would cancel out that velocity (with an impulse "go to angle and return to neutral position" motion). Overlaid on that was also a small proportional gain which would tend the ball towards the center of the platter.

My question: What is the professional/ correct solution to this situation (where your controller can only hit the system with impulses rather than continuous feedback)?

Here is a picture of the setup: enter image description here

Sneaky Polar Bear
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A slightly dampened negative feedback loop. Where bal.posX dictates strength y.rot.arm ?

https://en.wikipedia.org/wiki/Control_system

I once coded something alike it, my colleague who's into PLC's called it that. I did fuzzy logic optimization then..

user613326
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