Kinematic Study of a Spatial Hybrid Manipulator for Robot-Assisted Surgery

Abstract

The recent developments in the field of robotics lead to the replacement of conventional machines as well as human beings employed to a specific work. In the last three decades, a lot of research has been carried out in all the major domains of robotics like kinematics, dynamics and controls. The scope of this thesis is limited to kinematic study only. It has been found in the literature that the pioneer work done by Denavit and Hartenberg to develop the kinematic model of a serial manipulator, is limited to open-loop manipulators only. A couple of other ambiguities are also reported by different researchers in the past. The main focus of this work is to develop the kinematic model of a hybrid manipulator, which is a combination of open- and closed-loop chains containing planar and spatial links. The positional and orientational inconsistencies are observed, when such hybrid manipulators are modeled with the D-H parameter method. To overcome these inconsistencies, the concept of dummy frames is proposed in the present thesis and successfully implemented on the prototype of a hybrid manipulator, which is a 7-DOF manipulator being developed for medical/surgical applications at CSIR-CSIO lab, Chandigarh. Moreover, the analytical formulation of the spring design for gravity balancing of the hybrid manipulator is also presented in the current thesis.