Berechnung der optimalen Getriebeübersetzung von industrie- roboterantrieben nach dem kennlinienfeld des servomotors

Abstract

The principal performance parameter for a robot joint is torque. In the case of electrical actuation the available torque is used to support statically the arm and load. In practice there are also dynamic torque requirements associated with moving the load from point to point in an acceptable period of time with a given velocity profile. It is usually permissible to overload an electric motor to obtain the additional torque provided that the maximum allowable winding temperature is not exceeded. Therefore, an appropriate gearbox transmission ratio must to be selected to minimize the time required to perform a specified move distance with minimum motor power and the best performance of the joint drive. The object of this paper is to determine the optimum gear-box transmission ratio for industrial robot drives under consideration of the commutation limit curve of the dc servo motor and the velocity profile. The velocity profile after Bestehorn (dynamically smoother motion[1]) is considered. Minimum time for a given move distance is obtained when the optimal transmission ratio, i ges opt , equals. i ges opt = 0.357 C ϕ ̈ j ges A max C 2 ϕϕ L max KM M d b 2 3 Because optimal transmission ratio is proportional to the cube root of the move distance and the load, a transmission ratio can be chosen which is close to optimal for a fairly large range of the distance and load.