Parallel kinematics for machine tools

Parallel kinematics is a branch of mechanics that focusses on manipulators formed by closed kinematic chains, i.e., mechanisms that have an endeffector joined to the fixed frame by several limbs. Such a kinematic structure provides some advantages regarding stiffness, acceleration and weight, but has some drawbacks due to mechanical complexity and limited workspaces. In the field of machining, there have been several applications of such mechanisms to machine tools. Earlier designs based on hexapods did not fulfil expectations but new topologies are promising. In this chapter, there is first a description of the evolution of parallel kinematics in the manufacturing industry. Second, the authors expose a design methodology giving some hints on the main problems to overcome. Third, there is a study on calibration processes that can be applied to these machines. And, at the end, there is a description of control issues.