RMCTools has a auto tuner or gain optimizer that works very well most of the time. A question has been asked about how small changes affect the RMC’s ability to control position, velocity and acceleration. We use a simple linearized model for the hydraulic actuator’s open loop transfer function.

These parameters approximates moving a 2900 kg mass using a hydraulic cylinder 1000x63x40mm. The supply pressure is 200 bar and the valve is a 100 liter/min valve. This is a realistic load for testing.

So how much do varying loads and oil temperature changes affect motion?

One way to find out is to calculate the controller gains using the parameters above, then use these same parameters on a model where the parameters have changed by 10%. The RMC tuning wizard is much more accurate than +/- 10%.

So first I will make a move from 0 to 500mm at 500mm/s with an acceleration of 2500mm/s^2. The ramp time will be 0.2 seconds.

The open loop parameter are those listed above.

The controller gains are shown in the picture along with the mean squared error and the position error as a function of time.

It is easy to see the response is too good. There is only about 0.002mm of error.