Hierarchical Controller for Obstacle Avoidance Task in WMRs Considering Actuators and Power Electronics Subsystems: When Artificial Potential Fields Approach is Used

Through the development of a three-level hierarchical controller, this study proposes a solution to the obstacle avoidance task in wheeled mobile robots (WMRs). The proposed controller takes into consideration the dynamics of the three subsystems that typically compose a WMR (mechanical structure, actuators, and power electronics). At the high level, a control based on input-output linearization that uses the artificial potential fields technique is used and a Lyapunov-alike function is proposed for stability analysis purposes. At the medium level, two controls based on differential flatness are employed and a Hurwitz-stable-type polynomial is defined with the aim of locate the poles on the left-hand-side of the complex plane. Finally, at the low level, two cascaded controls are implemented using sliding modes and PI control. The performance of the three-level hierarchical controller is evaluated through a co-simulation using Matlab-Simulink and PSpice software. The obtained results are assessed with a two-level controller that does not take into account the dynamics of the power stage. Such results demonstrate that both controllers accomplish the obstacle avoidance task when no kind of perturbations are considered. However, and unlike the two-level controller, the three-level hierarchical controller successfully achieves the obstacle avoidance task even when disturbances in some parameters of the system are introduced.