Target circumnavigation of mobile robots using range-only measurements

This paper presents a control scheme to steer a nonholonomic robot to enclose an unknown target in both obstacle-free and obstacle-presence environments. Unlike most literature, we consider the situation where the robot with unknown position and orientation obtains only the distance to the target and detects collisions with obstacles. We first select a virtual point and construct new states to facilitate the controller design. For the obstacle-free case, a dynamic output feedback controller is derived to ensure that the distance between the robot and the target globally converges to a desired constant. The smooth bounded controller is computationally efficient and can be easily implemented. For the obstacle-presence case, a collision-allowed control strategy is developed to guarantee that the robot escapes from circular obstacles and eventually maintains a given distance from the target. Numerical simulations and practical experiments are performed to verify the effectiveness of the control method.