Trigonometric Ratio-Based RCM Mechanism for Bone Drilling

This research proposes an improved RCM mechanism in which a pair of linear actuators and a gearless arc-guide are employed to achieve high rigidity and resolution, which enable bone drilling. A vision-guided navigation system is also integrated into the proposed system to automatically guide the orientation.


SeongBo Shim


Trigonometric Ratio-Based Remote Center of Motion Mechanism for Bone Drilling
Shim S, Lee S, Ji D, Choi H, Hong J
Proceeding of IROS 2018, 2018


An albased diagnostic and minimally invasive surgical robotic system for precise treatment of hematologic bone diseases
Ministry of Trade, Industry and Energy

RCM mechanism

● Purpose

– To withstand the drilling force, the RCM mechanism should have high rigidity for tilting rotation.

– To conduct the drilling precisely, the RCM mechanism should have a high resolution.

– To position the RCM mechanism using a passive arm, the mechanism should have a compact structure.

Kinematic model

Trigonometric-ratio for tilting motion

– Ratio of distance equal to the ratio of feed rate


● RCM motion

– Accuracy of RCM points : 0.42 mm

Experiments and results

● Evaluation of RCM accuracy

– The total RMS error of RCM points : 0.42 mm

– RMS error : [0.22 0.28 0.22] mm


– Maintain its tilting angle up to 50 N

Conclusion and future work

● Conclusion

– We developed a new mechanical type of RCM mechanism for bone drilling based on trigonometric ratio.

– T-RCM has sufficient accuracy and rigidity with compact structure.

● Future work

– The rolling friction based drilling mechanism will be integrated with the T-RCM for auto drilling.

– Force analysis and drilling test will be conducted using swine or cadaver bones.