Force capability evaluation methods for bilateral controlled manipulators

Manipulating force ellipsoid and force polytope are measurements to evaluate force capability of manipulators. This paper extends these measurements to bilateral controlled manipulators. Control goals of bilateral control are synchronizing position and realizing the law of action and reaction between master and slave. In the steady-state, master and slave should output same magnitude force in reverse direction to realize the law. Therefore, force capability of the whole system is regulated by master or slave which has smaller force capability. Thus, an intersection between two force ellipsoids or polytopes of master and slave represents force capability of the system. In this paper, two methods are proposed to evaluate the intersection considering gravity: one is based on force polytopes, and the other is based on manipulating force ellipsoids. Numerical examples are provided to compare characteristics of two methods.