Abstract

In this research a passive haptic interface is explored as a surgical aid for dental implant surgery. The placement of a dental implant is critical since positioning mistakes can lead to permanent damage in the nerves controlling the lips, long lasting numbness, and failure of the implant and the crown on it. Haptic feedback to the surgeon in real time can decrease dependence on the surgeon's skill and experience for accurate implant positioning and increase the overall safety of the procedure. The developed device is a lightweight mechanism with weight compensation. Rotary magnetorheological (MR) brakes were custom designed for this application using the serpentine flux path concept. The resulting MR-brakes are 33% smaller in diameter than the only commercially available such brakes, yet produce 2.7 times more torque at 10.9 Nm. Another contribution of this research was a ferro-fluidic sealing technique which decreased the off-state torque. The control system implemented the passive force manipulability ellipsoid algorithm for force rendering of rigid wall-following tasks. Usability experiments were conducted to drill holes with haptic feedback. The maximum average positioning error was 2.88 mm along the x axis. The errors along the y and z axes were 1.9 mm and 1.16 mm, respectively. The results are on the same order of magnitude as other dental robotic systems. The innovative new MR-brake actuators, inherent safety of the system, and simplicity of control make this passive haptic interface a viable option for further exploration.

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