MPC robotic arm with stepper motor control

Hello, i am currently doing a robotic arm project and i am trying to implement the MPC controller on the stepper motor control of the robotic arm. The simulation works well when there is no stepper motor control involve where there is only robotic arm dynamics.

However, when i try to design the mpc system with feedback of encoder angle as a measured output (MO), this error occured;

"Plant model cannot be a pure direct feed-through system without additional dynamics error."

The file attached is my simulink model and the matlab m file for the encoder block.

Can anyone kindly give me some suggestion to modify on this model in order to control the stepper motor of robotic arm using arduino?

Answer 1

[Emmanouil Tzorakoleftherakis]

The prediction model you provided has direct feedthrough which is not currently supported by Model Predictive Control Toolbox. We are currently working towards adding this functionality at a future release. In the meantime, I suggest modifying the prediction model to remove the direct feedthrough (maybe you can add an additional state that incorporates a delay or something equivalent)