Tuning for force tracking in MR (Magneto-Rheological) dampers

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Shuhaibul
I already create MR damper modelling by using non-parametric linearised data driven (NPLDD) double input model. The hysteresis curve behavior is 99.9% followed as per experimental data, Figure below:

Plot of force against velocity at 0.5 A showing a looping hysteresis curve; blue NPLDD Double Input curve closely overlays red Experiment curve, force -3000 to 3000 N, velocity -0.2 to 0.2 m/s.

Then, by using this model, I had created closed loop model for force tracking control. The closed loop is developed by using continuous state control and If-Then Rules block as below:

Simulink block diagram of a closed-loop force tracking controller: Fd_des minus Fd_act gives Fd_error, passes through Gain G and a Product with Sign of velocity, into If-Then Rules and NPLDD Single Input model, with Memory and Gain1 B feedback.

The input Fd_des and velocity is set to be sine, square, and sawtooth waveform, so that the output (Fd_act) will exhibit the same as input (Fd_des). However, after several time tuning the value of G and B, the result for force tracking (F_act vs F_des) is not the same as below:

Line graph titled Force Tracking plotting Force (N) against Time (sec) from 0 to 350; a smooth blue sinusoid, Force Desired, swings between about -400 and 400, while a green Force Actual trace shows jagged jumps and does not follow it.
Line plot titled Force Tracking, Force (N) against Time (sec) from 0 to 350; a square-wave Force Desired (blue) steps between about 180 and 400 with a spike to about -400, while Force Actual (green) follows with large spikes up to about 1600.
Line graph titled Force Tracking plotting Force (N) against Time (sec) from 0 to 350 s. A blue sawtooth Force Desired line runs from about 400 N down to -400 N and resets repeatedly, while a green Force Actual line stays mostly between -150 and -300 N, spiking only at each reset.

All the result is not followed/tracked the input. The value of G and B are 0.05 and 2 respectively.
 

Discussion

Are you trying to get the graphs to match as close as possible? It was not clear to me in your problem statement. Are those spikes due to something in the IF-THEN part of your control system, causing an abrupt change?
 
Thanks for your response. My aim is to get the graph to be match as close as possible. If the output graph follow exactly the input graph, the the force tracking tuning will be true. The spikes may due the tuning of G and B values. IF-THEN rules is used to ensure the input current will be in between 0 to 0.9A. Do you have any idea how to tune the G and B value? Or need to change to PID controller?