Design and optimization of a parallel guidance device for minimal invasive spinal surgery

For most of the spinal surgeries, the pedicle screw insertion operation is a significant difficult procedure. To solve accurate position and keep the screw path in operation, a parallel guide device based on 3-RPS parallel mechanism is proposed in this paper. According to three degrees of freedom (Dofs), the inverse solution of the parallel mechanism, the workspace of parallel mechanism and institutional flexibility are calculated. And based on the finite element analysis, first six order natural frequency of parallel mechanism are analyzed. The integrated optimization method is used based on the kinematics and dynamics indexes. The frequency of the dynamic response of the different dimensions is gained by finite element software. The experimental design of Box-behken is used to get more sample data for fitting function by using least square method. Work spaces of institutions and frequency of the dynamic response is got. Kinematic indexes are the work spaces and institutional flexibility and the indexes of the dynamics is the first-order frequency response. Both as the objective function, to get optimal structural parameters size by genetic algorithm optimization based on kinematics and dynamics. By this approach, a good kinematics index and dynamic index of the parallel mechanism are obtained. Such a combination of both the formation of multi-objective optimization design can provide the basis of strong theoretical guidance for future engineering applications.