Real-Time Medical Tool Runout Monitor Based on Dual Laser Displacement Sensors

Objective: Robot-assisted drilling or milling is used widely in surgeries concerning bones, which is restricted in precision and safety due to tool bit runout. This paper aims to achieve real-time accurate runout status monitor, to support safer surgeries. Methods: First, a rigid tool runout model is constructed. An orthogonal dual laser tracking structure and relevant calibration methods are then proposed. An algorithm is finally proposed to realize tool tip tracking under eccentrical load with the tool model and tracking structure. Results: The experiment under no load indicated a high accordance between the model and the measurement. Relative errors of 8.11% and 14.96% were presented in accuracy tests on x and y, respectively, while 5.5 mu m and 6.2 mu m absolute error were presented for precision. Moreover, the method was able to differentiate different stages during drilling under eccentrical loads. The calculation efficiency reaches 1736 fps. Conclusion: The proposed method can provide real-time accurate surgical drilling tool position status, proving the potential to improve the safety of surgeries.