Tracking Control of Unicycle Mobile Robots With Event-Triggered and Self-Triggered Feedback

This article studies the tracking control problem for unicycle mobile robots with event-triggered and self-triggered feedback. Based on a modified dynamic feedback linearization technique and a refined stability analysis, we first propose a new class of saturated sampled-data controllers for unicycle mobile robots of which the state is subject to sampling (measurement) errors. It is guaranteed that the generated control inputs are restricted to within desired ranges, and the unicycle trajectory practically converges toward a time-varying trajectory as long as the sampling errors satisfy a saturated sector bound condition with a nonnegative offset. The proposed robust controller gives rise to a novel event-triggered sampling mechanism with a saturated threshold signal, which adjusts the sampling errors online to steer the tracking error to a desired neighborhood of the origin and guarantees a positive lower bound for the intersampling intervals. As a special case, by designing appropriately the controller and the event-triggered sampling mechanism, asymptotic tracking is achievable. New self-triggered and periodic sampling mechanisms are also developed as natural extensions of the event-triggered tracking control result. Both numerical and physical experiments are employed to validate the effectiveness of the proposed event-based control methodology.