Distributed cooperative tracking for multiple second-order nonlinear systems using only relative position measurements

In this paper, a distributed cooperative tracking problem is studied for a group of second-order nonlinear systems. The control goal is to drive the states of the followers to converge to those of a time-varying leader using only relative information. We focus on the case of the output feedback, where the velocities of the followers and the leader are not available. Two kinds of distributed observers are proposed for the cases when the follower dynamics are uniformly globally exponentially stable and the follower dynamics are continuously differentiable, respectively. Using the observer outputs, we design the control inputs such that the distributed cooperative tracking problem of multiple second-order nonlinear systems is solved under the constraint that only relative position measurements are available. Simulations are given to validate the theoretical results.