This book focuses on the synthesis of lower-mobility parallel manipulators, presenting a group-theory-based method that has the advantage of being geometrically intrinsic. Rotations and translations of a rigid body as well as a combination of the two can be expressed and handled elegantly using the group algebraic structure of the set of rigid-body displacements. The book gathers the authors' research results, which were previously scattered in various journals and conference proceedings, presenting them in a unified form. Using the presented method, it reveals numerous novel architectures of lower-mobility parallel manipulators, which are of interest to those in the robotics community. More importantly, readers can use the method and tool to develop new types of lower-mobility parallel manipulators independently.

This book contains mechanism analysis and synthesis. In mechanism analysis, a mobility methodology is first systematically presented. This methodology, based on the author's screw theory, proposed in 1997, of which the generality and validity was only proved recently, is a very complex issue, researched by various scientists over the last 150 years. The principle of kinematic influence coefficient and its latest developments are described. This principle is suitable for kinematic analysis of various 6-DOF and lower-mobility parallel manipulators. The singularities are classified by a new point of view, and progress in position-singularity and orientation-singularity is stated. In addition, the concept of over-determinate input is proposed and a new method of force analysis based on screw theory is presented. In mechanism synthesis, the synthesis for spatial parallel mechanisms is discussed, and the synthesis method of difficult 4-DOF and 5-DOF symmetric mechanisms, which was first put forward by the author in 2002, is introduced in detail. Besides, the three-order screw system and its space distribution of the kinematic screws for infinite possible motions of lower mobility mechanisms are both analyzed.

This book focuses on the synthesis of lower-mobility parallel manipulators, presenting a group-theory-based method that has the advantage of being geometrically intrinsic. Rotations and translations of a rigid body as well as a combination of the two can be expressed and handled elegantly using the group algebraic structure of the set of rigid-body displacements. The book gathers the authors' research results, which were previously scattered in various journals and conference proceedings, presenting them in a unified form. Using the presented method, it reveals numerous novel architectures of lower-mobility parallel manipulators, which are of interest to those in the robotics community. More importantly, readers can use the method and tool to develop new types of lower-mobility parallel manipulators independently.

This book contains mechanism analysis and synthesis. In mechanism analysis, a mobility methodology is first systematically presented. This methodology, based on the author's screw theory, proposed in 1997, of which the generality and validity was only proved recently, is a very complex issue, researched by various scientists over the last 150 years. The principle of kinematic influence coefficient and its latest developments are described. This principle is suitable for kinematic analysis of various 6-DOF and lower-mobility parallel manipulators. The singularities are classified by a new point of view, and progress in position-singularity and orientation-singularity is stated. In addition, the concept of over-determinate input is proposed and a new method of force analysis based on screw theory is presented. In mechanism synthesis, the synthesis for spatial parallel mechanisms is discussed, and the synthesis method of difficult 4-DOF and 5-DOF symmetric mechanisms, which was first put forward by the author in 2002, is introduced in detail. Besides, the three-order screw system and its space distribution of the kinematic screws for infinite possible motions of lower mobility mechanisms are both analyzed.