An improved pseudoinverse solution for redundant hydraulic manipulators

Abstract

The paper deals with the kinematic redundancy control of a 3DOF linear hydraulic manipulator moving in the vertical plane. The analysis is carried out in actuator coordinates so as to make the results usable in control schemes with actuator position feedback. The idea is to use the initial manipulator configuration as an optimization parameter in order to: (I) further minimize the actuator velocities obtained by a pseudoinverse solution, (II) simultaneously avoid actuator limits without recourse to a gradient projection approach. An improved pseudoinverse redundancy solution is thus obtained and implemented in a simple, non-iterative algorithm suitable for real-time applications. Simulations of a typical task with the proposed method show that minimizing the actuator velocity norm yields better results than minimizing the manipulator kinetic energy.