Heterogeneous Formation Tracking for Fixed-Wing UAVs and Nonholonomic UGVs With Different Asymmetric Constraints

This paper addresses heterogeneous formation tracking control (FTC) problems of fixed-wing unmanned aerial vehicles (UAVs) and nonholonomic unmanned ground vehicles (UGVs) subject to velocity constraints, where fixed-wing UAVs in 3D space and nonholonomic UGVs in 2D plane possess different asymmetric constraints. Based on sliding mode theory, a solution to heterogeneous FTC problems with asymmetric velocity constraints only using the relative position and orientation of leader (tracking target) is given, without requiring the leader's linear and angular velocities. It is noteworthy that by collaborative selection of parameters in control protocols proposed in this paper, the upper and lower bounds of the linear and angular velocities associated with fixed-wing UAVs and nonholonomic UGVs can be made nearly identical to those of the leader. Consequently, the feasibility set of leader's motion can be greatly expanded. Unlike existing linearization methods related to heterogeneous formation, the solution proposed in this paper does not suffer from singularity issues. The closed-loop stability of fixed-wing UAVs and nonholonomic UGVs under the proposed control protocols is proven by Lyapunov theory. The effectiveness of the theorical findings is further verified through simulations.