Trajectory tracking control of circular formation of agents with tracking different reference variables

This paper deals with trajectory tracking control problem for multi-agent systems with nonlinear dynamics. We propose two control strategies based on a same circular formation control law with limited communication to move agents to the desired positions, which is distinguished by tracking two different time-varying reference variables (heading of leader and center positions) respectively, simultaneously with the requirement that all the desired distances between neighboring agents are equal. We show that two different control problems are possible in such cases: 1) The first control strategy we called parallel motion control permits that all agents with uniform distributed circular formation move to the desired position without requiring rotation motion. 2) Translation motion control is the second strategy, which permits that all agents with uniform distributed circular formation move to the desired position with requiring rotation motion. In addition, by comparing the two cases, we discuss the results, and find their advantages and disadvantages. Numerical examples illustrate all results.