Manipulator apparatus with energy efficient control

Abstract

Manipulator apparatus is provided with an energy efficient control arrangement. The control arrangement in a point-to-point mode of operation utilizes a servo valve to selectively admit fluid from a pressurized source to one end of a cylinder. A piston is slidably mounted within the cylinder and connected to move a manipulator arm that is movable in a plurality of axes. The servo valve is closed when a predetermined arm velocity is reached and a bypass valving arrangement is opened to interconnect the ends of the cylinder. At a predetermined position of the manipulator arm, the control arrangement closes the bypass valving arrangement and the manipulator arm is decelerated as the arm approaches the desired final position. The pressurized source includes an accumulator and two high pressure check valves that each connect a respective end of the cylinder to the accumulator when the pressure at the respective end of the cylinder exceeds the accumulator pressure to supply pressurized fluid to other axes of the manipulator. The control arrangement compares the deceleration of the arm with a reference table of scheduled points representing desired velocity at respective positions to selectively control the opening and closing of the bypass valving arrangement during deceleration. During repetitive work or repeat cycles of operation, the reference table is modified in accordance with adaptive procedures to provide accurate control of the deceleration of the arm and the point at which the bypass valve is closed to initiate the deceleration.