Robot motions in task space with control constraints

This paper considers the problem of position control of robotic manipulators in task space. Based on Lyapunov stability theory, it is shown that the control strategy proposed is asymptotically convergent to the task error whose ultimate bound can be made arbitrarily small. As opposed to most other existing approaches, our algorithm also takes into account actuator constraints when positioning the end-effector to its desired final location. Moreover, it produces continuous controls with respect to time which are very desirable in all control algorithms. Computer simulations are presented for a two degree-of-freedom direct drive robot arm which are in accordance with the theoretical analysis. They also confirm that the proposed control strategy provides a simple and effective means of obtaining high accuracy end-effector positioning.