A nonlinear feedforward-feedback controller design for formation control of multi-robot systems

This paper deals with formation control problem of a flock of nonholonomic mobile robots in the leader-follower framework. In consideration of some practical factors, the formation system is always accompanied with both matched and mismatched uncertainties. The developed algorithm incorporates a fuzzy feedforward compensator into sliding mode controller (SMC). Adjustable defuzzifier weights enhance accuracy of fuzzy compensator to approximate uncertainties, further, the real-time control of follower robots can be achieved by tuning the output of SMC. The utilization of the fuzzy techniques can release the limitation on the known boundary of uncertainties which is required for the traditional SMC. The system stability and the convergence of tracking errors are proved using the Lyapunov stability theory. Performance is assessed by simulating the combined feedforward-feedback controller on a platform composed of three robots.