Inverse kinematic solutions for a fully parallel robot with singularity robustness

In this paper; two inverse-kinematic solutions with singularity robustness for a fully parallel robot manipulator are proposed. First, two inverse-kinematic solutions are presented based on the damped least-squares method, where the first solution (OSVC) is derived using a velocity constraint, and the other (OSFC) uses a force constraint. It can be shown that both solutions are special cases of a general damped least-squares method (GIKS). Next, under the assumption that direct position measurement is available, a feedback-correction term is introduced into the general damped least-squares method to eliminate positioning error in resolved-rate control. It can be shown that both solutions are stable with bounded errors, but each has its own relative merits and shortcomings. Illustrative examples are also given to show their effectiveness in practical applications.