Suboptimal Control Design for Differential Wheeled Mobile Robots with θ − D Technique

In this paper, a suboptimal controller is designed by the θ −D technique for a differential wheeled mobile robot with holonomic and nonholonomic constraints. The challenge of wheel actuators not being exerted into the coordinate of the robot base is addressed by a proper transformation, leading to controllability of the mobile robot system. This transformation lowers the complexity of control design since it yields reduced-order state-space equations. The θ − D algorithm provides an approximate closed-form suboptimal controller that is easy to implement onboard. It is compared favorably with the similar state-dependent Riccati equation technique in terms of computation efficiency and control effort. The simulation experiments verify that the proposed technique is an effective and efficient tool for designing the controller of the differential wheeled mobile robots.