Optimal Reduction Ratio Selection for the Driving System of High-speed Parallel Manipulator

Abstract

The small-medium powered AC servomotors and the matched precision gearboxes,being able to amplify output torque and reduce output speed,are widely used in the driving system of the high speed parallel manipulators.The reduction ratio of the driving system plays a very important role in the accelerating capacity,decelerating capacity and operation speed for a parallel manipulator.A new S-curve speed profile,which can help to plan the trajectory of the end-effecter of the manipulator for minimum residual vibration,is introduced.An optimal reduction ratio selection method for the driving system,which takes the applying principles of the AC servomotor as constraint conditions and aims at the minimal operation time,is proposed.A parallel manipulator with 2 degrees of freedom is taken as example.Based on inverse dynamics modeling and trajectory planning,a non-linear program with some constraints is carried out.The simulation results illustrate the effectiveness of the optimization method.The optimization method can also be used to make full use of the advantages of the AC servomotor and consequently reduce the cost of manipulator.The optimization method can also be applied in designing other parallel manipulators.