Plate-and-Cable (PAC) Haptic Device for Orthopaedic Training

This paper presents the design of a 6-DOF hybrid impedance/admittance haptic device that targets simulation of bone drilling and related tasks. We present a prototype optimized for applications like bone drilling, cutting bone, spinal awl probe use, and other surgical techniques where a combination of high force and low impedance is required in different directions. The required performance cannot be satisfied by existing, off-the-shelf haptic devices. This design may allow critical improvements in simulator fidelity for surgery training. The device consists of two low-mass (carbon fiber) plates with a rod passing through them and constrained to move in only 2 DOF, allowing axial torque to be displayed to the user’s hand. These two parallel plates are controlled by four cables pulled by motors. We derive the forward kinematic equations and present the predicted distribution of location error, cable velocity, cable tension, and output force. These results and hardware tests indicate that this design may provide a revolutionary approach for the haptic display of many surgical procedures by means of an architecture that allows arbitrary workspace scaling.