Preview and stochastic controllers for motion control of robotics manipulator with control input constraints

A preview controller and a stochastic controller are synthesized to control the motion of an n-degrees of freedom direct drive robotics manipulator. The behavior of the two controllers are indicated with deterministic and stochastic disturbances. The proposed preview controller is implemented off-line and the optimal problem is solved at an arbitrary operating point of a prespecified optimal trajectory. While design of the proposed stochastic controller is based on the minimum variance control with model reference depends on the nominal values of the position and angular velocity of the manipulator´s joints. The least squares sense is used online to estimate the parameters of the stochastic controller. In the proposed two controllers, the end effector´s velocity is monitored in a servo loop, as well as the position and angular velocity of each joint of the manipulator are compelled to track their nominal values. These two controllers comprise an n-input vector of the actuators torque, and 6-output vector of the linear and angular end effector´s velocities. The actuators of the direct drive manipulator are taken as DC servo motors. Their dynamics and constraints are introduced in the proposed two controllers. Computer simulation results are made to demonstrate the applicability, robustness and the tracking performance of the preview and stochastic controllers. Comparison between their performance is also given