Time-optimal control of hydraulic manipulators with path constraints

A method of optimization intended to speed up motions of non-redundant hydraulic manipulators along prescribed paths of their end-effectors is presented. A parametric path of the end-effector of a non-redundant manipulator determines the corresponding path in the manipulator joint-space. The optimization problem therefore reduces to finding the optimum distribution of the parameter of the path in time. The proposed optimization scheme is based on discretization of the distribution of the parameter into a fixed number of points, and finding their optimum locations by methods of constrained nonlinear programming. Incompressibility of the hydraulic fluid is assumed throughout for greater effectiveness of the procedure. Results of sample optimizations performed on a three-link hydraulic excavator are presented.