Researching Of Input Selection Base On Performance Index For Parallel Mechanisms With Actuation Redundancy

With the development of science and technology, the application field of parallel mechanism is becoming wider and wider. Such as in the field of aerospace, computer aided manufacturing, machinery manufacturing and so on. In general, one parallel machanism have a number of reasonable inputs. All those inputs can accomplish the desired movement of the paralell mechanism. When different inputs are choosed, the performance of mechanism is quite different. Therefore, the inputs selection based on performance is worthy studying. This paper, are mainly study the inputs selection of the parallel mechanisms with one redundant actuated pair or one redundant actuation branched chain, they are based on the dexterity and minimum stiffness.Through analyzing for the constraint screws and driving screws of the completely symmetrical mechanism in the initial position, a method which could be used to choose the actuated pairs of the parallel mechanism was presented. The method is through analyzing and comparising the angle of the driving screws and the datum which we choose. The actuated pairs which can get the best performance of the parallel mechanism are choosed.This paper optimize the inputs selection of 3T, 2T1 R, 2R1 T, 3T1 R parallel mechanisms with one redundant actuation branched chain and 3T, 2R1 T, 3T1 R parallel mechanisms with one redundant actuated pairs, which are based on the dexterity and the minimum stiffness. At last, the laws of the dexterity and the minimum stiffness changing with the angle of the driving screw and the choosed datum are founed. And then, the 4UPU/SPS mechanism as an example is analyzed by this method. And this method is confirmed by computer simulation.In additiom, the input selecting of 2R1 T parallel mechanism is analyzed by considering the dexterity and minimum stiffness in the meantime. The 3RPS parallel mechanism is choosen as the example. The performance of them with different redundant actuation branched chains are analysed. The dexterity of the mechanisms are calculated by MATLAB. And the stiffness of the mechanisms are simulated by using ANSYS software. The different performances of the mechanisms is caculated, when it has different redundant actuation branched chain.