Developing a Hybrid Cartesian Parallel Manipulator for Knee Surgery

In this paper, we use Cartesian parallel mechanism (CPM) as the key module of the constructed knee surgical robot. In the constructed robot, the limited workspace and high rigidity of Cartesian parallel manipulator provide the surgical robot with enhanced safety and high cutting accuracy. The complex kinematics of parallel manipulators is also avoided because of the decoupled feature of the CPM. The dynamics of the CPM is derived by using Langrage-D´Alembert principle. Using the dynamic model, the position control law is derived based on the computed torque method in order to compensate in the feedforward loop the coupled forces from other limbs of the CPM. The simulated and experimental results both showed that high positioning accuracy and desired position profile can be achieved by the proposed controller. The developed knee surgical robot using hybrid CPM in this paper thus offer a better mechanical architecture than other parallel surgical manipulators in terms of safety, cutting accuracy, and kinematics and control simplicity