Controlling angular momentum using PID

In an earlier post I had a look at controlling animation using PID-controllers. Generally, these controllers work on a single variable in a single dimensions. This is not always sufficient in a 3D world, so I wanted to explore the possibility of expanding it to more dimensions. Specifically I wanted to control orientation, and make my objects turn the right way using PID controllers.

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Animation using closed-loop control

A common choice for industrial control systems is a so called PID-controller, PID in this case stands for proportional, integral, and derivative, referring to the three linearly combined terms producing the controller output. The coefficients, usually called gain, are the ones determining the behavior of the controller, and are (usually) not time dependant.

I recently prototyped some camera movement routines, where I had a top-down view and basically set up a PID-controller to track the cameras position above ground, again taking the output as acceleration. This had the effect that I could simply set the new height as a set-point reference whenever I wanted to zoom in or out, and it would move there smoothly without a hitch. Rapidly updating the value, such as when moving laterally across different ground levels, was also handled smoothly and the movement felt natural.

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