The ability of a powered transfemoral prosthesis leg to perform a natural walking gait has been widely developed. Various kinds of control systems and mechanical structures have been implemented to achieve high performance in performing a natural walking gait. This thesis, developed and designed a powered transfemoral prosthesis leg prototype for above-knee amputee patients. This prosthesis used a linear actuator based four-bar linkage mechanism to drive the knee angle. An Inertial measurement unit (IMU) sensor was placed above the knee joint of the prosthesis to read the hip angle data of the subject, which is the main information for the system to calculate knee angle target. The received hip angle data, then processed to obtain some required features such as angle, peak to peak angle, deceleration, period, and angular velocity of the hip angle. Those features are then used to calculate the knee angle target for the prosthesis. Once the knee angle target specified, the combination of proportional integral derivative (PID) control and feedback knee angle from absolute encoder is used to control the movement of knee angle to achieve the predetermined target angle. The performance of the prosthesis was tested by real walking simulation conducted by an able-bodied subject. The thigh part of the prosthesis was connected to the thigh of the subject in parallel position through an aluminum bar. In the experiment the subject was walking on a powered treadmill to control the thigh motion of the prosthesis with three different walking speeds: 50cm/s, 60cm/s, and 70cm/s. The experiment results showed that the prosthesis was able to perform natural walking gait motion similar as the subject’s walking gait motion at the same time; and also the motion speed of the prosthesis was able to adapt the different walking speeds of the subject without changing any parameters value. Some simulation results using artificial neural network (ANN) algorithm in Matlab software were added as comparison. The root mean square error (RMSE) method was used to evaluate the performance of the prosthesis, the results showed that the faster walking speed of the subject, the higher its RMSE value. The higher RMSE value of the implemented algorithm in the prosthesis was 13.0º, when the walking speed the of subject is 70cm/s, this error also caused by the initial value difference between prosthesis’ knee angle and subject’s knee angle, this value’s difference was around 6.6º; and the higher RMSE value of the ANN simulation result was 4.4º for 70cm/s walking speed. The maximum knee angle performed by the prosthesis during the experiment was 60º from 90º range of motion.

[1] S. M. Behrens, R. Unal, E. Hekman, R. Carloni, S. Stramigioli and H. Koopman, "Design of a Fully-Passive Transfemoral Prosthesis Prototype," 33rd Annual International Conference of the IEEE EMBS, pp. 591-594, August-September 2011.
[2] H. Huang, T. A. Kuiken and R. D. Lipschutz, "A Strategy for Identifying Locomotion Modes Using Surface Electromyography," IEEE Transactions on Biomedical Engineering, vol. 56, no. 1, pp. 65-73, January 2009.
[3] A. L. Delis, A. F. da Rocha, I. dos Santos, I. G. Sene Jr, S. Salomoni and G. A. Borges, "Development of a Microcontrolled Bioinstrumentation System for Active Control of Leg Prostheses," Annual International IEEE EMBS Conference, pp. 2393-2396, August 2008.
[4] E. C. Martinez-Villalpando and H. Herr, "Agonist-antagonist active knee prosthesis: A preliminary study in level-ground walking," Journal of Rehabilitation Research & Development, vol. 46, no. 3, pp. 361-374, 2009.
[5] E. C. Martinez-Villalpando, J. Weber, G. Elliott and H. Herr, "Design of and Agonist-Antagonist Active Knee Prosthesis," Proceedings of the 2nd Biennial IEEE/RAS-EMBS International Conference on Biomedical Robotics and Biomechatronics, pp. 529-534, October 2008.
[6] R. Unal, F. Klijnstra, B. Burkink, S. Behrens, E. Hekman, S. Stramigioli, H. Koopman and R. Carloni, "Modeling of WalkMECH: a Fully-Passive Energy-Efficient Transfemoral Prosthesis Prototype," IEEE International Conference on Rehabilitation Robotics, June 2013.
[7] S. K. Au, J. Weber and H. Herr, "Powered Ankle-Foot Prosthesis Improves Walking Metabolic Economy," IEEE Transactions on Robotics, vol. 25, no. 1, pp. 51-66, February 2009.
[8] R. D. Gregg, T. Lenzi, L. J. Hargrove and J. W. Sensinger, "Virtual Constraint Control of a Powered Prosthetic Leg: From Simulation to Experiments With Transfemoral Amputees," IEEE Transactions on Robotics, vol. 30, no. 6, pp. 1455-1471, December 2014.
[9] E. J. Rouse, L. M. Mooney and H. M. Herr, "Clutchable series-elastic actuator: Implications for prosthetic knee design," The International Journal of Robotics Research, 9 October 2014.
[10] B. E. Lawson, B. Ruhe, A. Shultz and M. Goldfarb, "A Powered Prosthetic Intervention for Bilateral Transfemoral Amputees," IEEE Transactions on Biomedical Engineering, vol. 62, no. 4, pp. 1042-1050, April 2015.
[11] J. Markowitz, P. Krishnaswamy, M. F. Eilenberg, K. Endo, C. Barnhart and H. Herr, "Speed adaptation in a powered transtibial prosthesis controlled with a neuromuscular model," Philosophical Transactions of The Royal Society B, vol. 366, pp. 1621-1631, 2011.
[12] T. Lenzi, L. J. Hargrove and J. W. Sensinger, "Preliminary Evaluation of a New Control Approach to Achieve Speed Adaption in Robotic Transfemoral Prostheses," in International Conference on Intelligent Robots and System (IROS 2014), Chicago, IL, USA, 2014.
[13] F. Wang, K. Kim, S. Wen, Y. Wang and C. Wu, "Study of Gait Symmetry Quantification and Its Application to Intelligent Prosthetic Leg Development," Proceedings of the 2011 IEEE International Conference on Robotics and Biomimetics, pp. 1361-1366, December 2011.
[14] m. m. ag, Maxon Motor, 2016. [Online]. Available: http://www.maxonmotor.com/maxon/view/category/motor?target=filter&filterCategory=ec4pole. [Accessed 28 June 2016].
[15] m. m. ag, Maxon Motor, 2016. [Online]. Available: http://www.maxonmotor.com/maxon/view/product/gear/planetary/gp32/416930. [Accessed 3 July 2016].
[16] m. m. ag, Maxon Motor, 2016. [Online]. Available: http://www.maxonmotor.com/maxon/view/category/motor?target=filter&filterCategory=ec4pole. [Accessed 28 June 2016].
[17] Fahmizal, Development of a Sensor-Based Biped Robot Locomotion Controller for Uneven Terrain, Taipei: National Taiwan University of Science and Technology, 2013.
[18] C. L. Vaughan, L. B. Davis and C. J. O'Connor, Dynamics of Human Gait (2nd Edition), C. L. Vaughan, Ed., Western Cape: Kiboho Publisher, 1992.
[19] K. J. Waldron and G. L. Kinzel, Kinematics, dynamics, and design of machinery, United States of America: John Wiley & Sons, Inc, 2003.
[20] J. W. Sensinger, N. Intawachirarat and S. A. Gard, "Contribution of Prosthetic Knee and Ankle Mechanisms to Swing-Phase Foot Clearance," IEEE Transactions on Neural Systems and Rehabilitation Engineering, vol. 21, no. 1, pp. 74-80, January 2013.