A Model-Free Cascade Control Strategy for Trajectory Tracking in Mobile Robots

This work presents the implementation of a cascade control scheme for trajectory tracking of a mobile robot with an unknown dynamic model. The outer control loop is responsible for trajectory tracking, while the inner loop regulates the system velocity to compensate for the inherent nonlinearities of the dynamics. Furthermore, the proposed strategy is compared against a conventional PID controller, which also operates without requiring a system model. The robustness of the control approach is evaluated by subjecting the system to model perturbations, yielding an ISE of 1.073 and an ISCO of 106.75 for the PI controller, whereas the iPI achieved a lower ISE of 0.81 and an ISCO of 100.31. These results demonstrate that the modelfree controller exhibits superior performance in both trajectorytracking accuracy and disturbance rejection. Simulation tests were conducted using a dynamic model of the Pioneer 3-AT mobile robot, validating the effectiveness and robustness of the proposed control strategy.