Feed Forward for a 4-Bar Linkage

Our team is using a motor-driven 4 bar intake this season. We are new to this, and so I was wondering: is there a better way, beyond a profiled PID controller, to control the system? We are using feed forward models for the rest of our robot’s subsystems, but I couldn’t find any FF models for a 4-bar. Am I wrong in thinking that it is too complex a system to reasonably tune feed-forward for? If I am not, are there any other alternatives to not make this a purely PID controlled system?

Thanks!
Noah
Team Optix 3749 President and Programmer

The main question is why is a profiled PID not good enough here? A standard profiled PID controller can be perfectly suitable for many situations. For many 2 position intakes even a bang-bang control system will suffice.

I might be oversimplifying, but I think a 4-bar linkage can just be modeled the same as an arm.

If there is a difference (due to the center of mass potentially moving slightly differently from a circle), I think it would still model the effects of gravity well enough to be a vast improvement, and PID could do the rest.

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For an arm you’re almost always going to want a feedforward, whether or not you have a motion profile.