Hello Everyone. Thank you for reading this. I have a made a motion simulator pneumatically controlled. It is a bowl held by a stationary cradle with air cylinders tilting the bowl left,right, forwards and backwards. The software to control the cylinders is giving me fits. I am treating it with a simple linear function, ie; if distance from desired position to actual position >5 give cylinders some air if distance from desired position to actual position >50 give cylinders more air, etc. I get a lot of oscillations and overshoots. The air is compressible and I am moving weight either up or down a curve. (A model might be a pendulum with very high friction and the weight is a heavy sponge.) I think I must take into account starting position, inertia, lag, speed, etc. in a very high function equation. Any suggestions for me would be so appreciated, I do not know where to turn to learn more for this fun practical application.