Minimization of Energy Consumption for a Manipulator with Nonlinear Friction in PTP Motion.

Abstract

Robot engineering is developed mainly in the field of intelligibility such as in a manipulation. Considering the wide use of robots in the future, the robots should be studied from a viewpoint of saving energy because a robot is a kind of machine with an energy conversion.This paper deals with minimizing the energy consumption of a manipulator which is driven in a point-to-point control method. When the links of a manipulator are decelerated for positioning, the motors at the joints generate electric power. Since this energy can be regenerated to the source by using a chopper, the energy consumption of a manipulator is only by the heat loss of the electric and the frictional resistances. The minimization of the sum of these losses is reduced to a two-point boundary-value-problem of a nonlinear differential equation. The solutions of the equations are obtained by the generalized Newton-Raphson method. In this case the starting function for an optimal solution is selected from a view point of saving energy. It is seen from simulations that the second link of a two-link manipulator should be rotated backward in a certain condition.