We study grasps of multiinger dexterous hands under the point contact model. Speciically, we are interested in high-quality force closure grasps. We abstract the problem into the space of force/torque wrenches where the quality is proportional to the magnitude of the largest wrench expressed as a non-negative combination of the grasp wrenches. This abstraction enables us to solve the problem by...

The mathematical approach presented allows main features of kinematics and force transfer in the loaded natural tibiofemoral joint (TFJ) or in loaded knee endoprostheses with asymmetric condyles to be deduced from the spatial curvature morphology of the articulating surfaces. The mathematical considerations provide the theoretical background for the development of total knee replacements (TKR) ...

STUDY DESIGN Multicenter intraoperative biomechanical analysis. PURPOSE This study aimed to assess the maximal insertional torque (MIT) of lateral mass screw (LMS) and pedicle screw (PS) in the cervical or thoracic vertebrae during surgery. METHODS During posterior spinal fusion, cervical or thoracic multi-axial screws were placed at different cervical or thoracic levels and the MIT was rec...

The aims of this study were (1) to measure frequency-weighted vibration acceleration and (2) to study the effects of introducing a vibration-proof impact wrench on VWF in workers. The subject pool was 383 male workers who were regularly using an impact wrench and taking special medical examinations for vibration syndrome in a factory from 1982 to 1999. The prevalence of workers with VWF increas...

The wrench-closure workspace of parallel cable-driven mechanisms is the set of poses of their mobile platform for which the cables can balance any external wrench. The determination of this workspace is an important issue since the cables can only pull and not push on the mobile platform. This paper deals with the wrench-closure workspace of six-degrees-of-freedom (DOF) parallel mechanisms driv...

This paper presents a detailed analysis of the constant-orientation wrench-closure workspace of planar three-degree-of-freedom parallel mechanisms driven by four cables. The constantorientation wrench-closure workspace is defined as the subset of the plane wherein, for a given orientation of the moving platform, any planar wrench applied on the moving platform can be balanced by the cable-drive...

In this paper an analytic formulation of the statics and the instantaneous kinematics of robot manipulators based on the Grassmann-Cayley algebra is presented. The notions of twist, wrench, twist space and wrench space are mathematically represented by the concept of extensors of this algebra and the reciprocity relation between twist and wrench spaces of partially constrained rigid bodies is r...

This paper presents an advanced method to optimise the compliant structure of force-torque sensors at the design stage. To this end, some researchers used finite element analysis on the whole compliant structure or some of its components, while others proposed performance indices based on mechanism theory. This work proposes a new approach, which relies on a symbolic formulation of the wrench-d...