Two robust controllers are developed for the position and force control of a single n-joint nonredundant manipulator. The control strategies are shown to apply when the manipulator is unconstrained and when it is constrained by a rigid environment. Starting with the model of the robot dynamics and constraints in joint space, a dynamic equation is developed with respect to a set of task space coordinate variables. Using this task space model, the two control strategies are developed for the manipulator, and are shown to be robust with respect to uncertainty in the system. The robust control strategies have the following characteristics: (1) exponential convergence for motion tracking, (2) the controller is continuous for all times of interest, and (3) the controller is the same for constrained and unconstrained motion.>