Analysis and design of parallel mechanisms with flexure joints

Flexure joints are frequently used in precision motion stages and micro-robotic mechanisms due to their monolithic construction. The joint compliance, however, can affect the static and dynamic performance of the overall mechanism. In this paper, we consider the analysis and design of general platform type parallel mechanisms containing flexure joints. We consider static performance measures such as task space stiffness and manipulability, while subject to constraints such as joint stress, mechanism size, workspace volume, and dynamic characteristics. Based on these performance measures and constraints, we adopt the multi-objective optimization approach. We first obtain the Pareto frontier, which can then be used to select the desired design parameters based on secondary criteria such as performance sensitivity. To simplify presentation, we consider only lumped approximation of flexure joints in the pseudo-rigid-body approach. A planar mechanism is included to illustrate the analysis and design techniques. Tools presented in this paper can also be applied to a broader class of compliant mechanisms, including robots with inherent joint flexibility as well as compliant robots for contact tasks.