BACKGROUND: This paper presents the ongoing results of an effort to achieve the integration of a navigated cooperative robotic arm into computer-assisted orthopaedic surgery. A seamless integration requires the system acting in direct cooperation with the surgeon instead of replacing him. METHODS: Two technical issues are discussed to improve the haptic operating modes for interactive robot guidance. The concept of virtual fixtures is used to restrict the range of motion of the robot according to pre-operatively defined constraints, and methodologies to assure a robust and accurate motion through singular arm configurations are investigated. RESULTS: A new method for handling singularities is proposed, which is superior to the commonly used damped-least-squares method. It produces no deviations of the end-effector in relation to the virtually constrained path. CONCLUSIONS: A solution to assure a good performance of a hands-on robotic arm at singularity configurations is proposed. (c) 2007 John Wiley & Sons, Ltd.
BACKGROUND: This paper presents the ongoing results of an effort to achieve the integration of a navigated cooperative robotic arm into computer-assisted orthopaedic surgery. A seamless integration requires the system acting in direct cooperation with the surgeon instead of replacing him. METHODS: Two technical issues are discussed to improve the haptic operating modes for interactive robot guidance. The concept of virtual fixtures is used to restrict the range of motion of the robot according to pre-operatively defined constraints, and methodologies to assure a robust and accurate motion through singular arm configurations are investigated. RESULTS: A new method for handling singularities is proposed, which is superior to the commonly used damped-least-squares method. It produces no deviations of the end-effector in relation to the virtually constrained path. CONCLUSIONS: A solution to assure a good performance of a hands-on robotic arm at singularity configurations is proposed. (c) 2007 John Wiley & Sons, Ltd.