Optimal design of a 6-Dof haptic device

The work presented in this paper is motivated by the use of haptics in applications of medical simulation, particularly simulation of surgical procedures in hard tissue such as bone structures. In such a scenario haptic device characteristics such as stiffness, motions, suitable workspace and device footprint are key design factors. This paper presents a procedure for optimal design of a parallel kinematic structure for a 6-Dof haptic device. For optimization, performance indices such as workspace volume, kinematic isotropy and static actuator force requirements are defined. A specific Jacobian matrix normalization is introduced for defining the kinematic isotropy and actuator force requirement indices. For defining the optimization problem, a novel multi-criteria objective function is introduced. Based on this objective function, a genetic algorithm is used to solve the multi-objective and non-linear optimization problem. Also, sensitivity analysis of the performance indices against each design parameter is presented as a basis for selecting a final set of design parameters for prototype development. Finally, using these results, a prototype was implemented.