A Robot for Automated Motion Scaling in Robotic Microsurgery

1. A Robot for Automated Motion Scaling in Robotic Microsurgery Group 2 Keshav Chintamani Lavie Golenberg Prashanth Mathihalli

2. Problem Statement • Different surgical tasks require varying motion scales (MS) between the surgeon and the end-effector • E.g. Suturing vs. gross translation have different scale requirements • Surgeons currently keep the MS constant due to • Inconvenience and interruptions during procedures • Higher mental workload • Failures in selecting correct scales might lead to fatal errors • May require an additional technician

3. Currently… • A touch screen allows the surgeon or technician to change the motion scale value • The scale is a semi circle with a minimum value of 1 and a maximum of 10 • Tapping the circumference changes the MS value of the Zeus robot

4. Specific Aims • Design and construct an Automated Motion Scaling Robot (AMSR) • Hardware • Software • Integrate the AMSR with zeus robot system • Analysis and validation of the AMSR through an objective human factors study

5. The Hypotheses The AMSR will: • Eliminate the need for a technician • Remove pauses during operations • Be capable of changing the MS more frequently • Deliver MS changes more accurately than a human • Not be susceptible to fatigue • Create a more responsive system

6. Hardware

7. Design Requirements • A two degree-of-freedom (DOF) RP robot arm • One rotational and one prismatic joint • Damping mechanism to prevent damage to the touch screen • Rapid input/output response • Provide accurate responses to inputs from the surgeon • Provide ease of removal during maintenance and repair

8. Design Requirements, Contd.. • Designing the Robot Mount to provide • A high center-center accuracy between the AMSR and the Motion Scale • Variable chassis geometry settings for the AMSR for calibration

9. Design Hurdles • Providing motors with sufficient torque • Providing a unique design that is • Replaceable • Reliable • Sensitive to pressure

10. Preliminary Concepts for the Prismatic Joint

11. Motor Selection • A high torque motor was chosen for the base (rotation) • 300 deg/sec Angular Velocity • 11 Kg/cm Peak Torque • A light weight motor for tapping (translational) • 24 g net weight • 3 Kg/cm Peak Torque • 350 deg/sec angular velocity

12. Software

13. Electronics • Robix RCS-6 Controller • Controller provides support for • 6 servos with 6 sensor inputs • Parallel port data transmission • The programming was done in Microsoft Visual C++ 6.0

14. Robot Control Software • Fully integrated control functions for • Speed, acceleration and deceleration of servos • Positional feedback • Additional sensor data acquisition capabilities

15. Final Design

16. Final Design: 2D Views

17. Final Design: 3D View

18. A Descriptive Video

19. The AMSR!

20. Evaluation

21. Methodology • Obtain preliminary data for 3 humans and the AMS Robot performing a tapping task • Compare performance between the robot and the subjects

22. Preliminary Human Factors Test • Participants were provided with 5 minutes for practice on the MS display • They were asked to input 99 values based on verbal prompts from the experimenter • Participants were asked to tap values with and without a stylus • Values displayed on screen were recorded

23. Analysis • A within-subjects factorial design was used • The experiment was balanced using a Latin square • The data was analyzed for input error

24. Results, Discussion & Conclusion

25. Plots Error variation between AMSR and Human Error variation between factors

26. Overall Plots

27. Conclusion • Human beings are incapable of the level of dexterity that robots possess • Hand movements with a stylus improved human performance • The AMSR can provide more rapid and accurate cyclic responses than a human • These responses are repeatable

28. Conclusion, contd… • With the AMSR, surgeon performance can immensely be enhanced • Surgeon fatigue and workload can be reduced • Can result in efficient surgeries with reduced time durations

29. Future Work

30. Future Work • Creating a closed loop system • Increase the accuracy of the robot • Continue subject testing • Analyze performance of linear scales over semi-circular scales • Provide various forms of input methods

31. Future Work, contd… • Combine AMSR with Automatic Motion Scaling • This study can lead to further research into human hand tracking performance • Develop display methods/cues for enhancing performance

32. Thank you

33. References • S. M. P. M. Sunil M. Prasad MD*, Hersh S. Maniar MD†, Celeste Chu MD*, Richard B. Schuessler PhD* and Ralph J. Damiano, Jr. MD*, Corresponding Author Contact Information, FACS, "Surgical robotics: Impact of motion scaling on task performance," 2004. • R. D. Ellis, A. Cao, A. Pandya, A. Composto, M. D. Klein, and G. Auner, "Minimizing Movement Time In Surgical Telerobotic Tasks," presented at 49th Annual meeting of the Human Factors and Ergonomics Society Orlando, Florida, 2005. • J. Accot and S. Zhai, "Scale effects in steering law tasks," CHI, vol. No.3, pp. 1-8, 2001. • P. M. Fitts, "The Information Capacity of the Human Motor System in Controlling the Amplitude of Movement," Journal of Experimental Psychology, vol. Vol. 121, pp. 262-269, 1954.