Analysis and Optimum Kinematic Design of a Parallel Robot

Parallel robots display important advantages over their serial mechanisms in several applications where both accuracy and dynamic response are needed. Parallel manipulators have been developed extensively for applications that need high accuracy, speed and stiffness, which make them, useful in important fields. But during the designing of the parallel mechanism, it is difficult to determine the dimension of structure and the workspace for the mechanism. For this cause, kinematic optimal design is an important key in designing parallel manipulators, and was received a big attention by researchers in the past decade. Thus, because of the strong dependence of geometric performances and their parameters, the design problems for the parallel robots are more complex and the efficacy of the design method become more difficult. In view of the fact that, the robot's performance depends on numerous factors, it is difficult to say that a particular design is the only solution to a given problem, even though for a robot with only one degree of freedom and four links. If the number of links and number of DoF augment, the design becomes more difficult for the robot. Thus, it is right to know how good a mechanism may run when it is still in the design stage.In this paper, we present first, the inverse kinematic problem and Jacobian matrix of the 3RRR parallel manipulator which is necessary for subsequent analysis, then, an optimal design study is achieved for a class of parallel robots in order to find a set of parameters that attain a good performance in terms of the important performances indexes: the workspace capabilities and dexterity. Finally, simulations results are obtained.