Improving Finite State Impedance Control of Active-Transfemoral Prosthesis Using Dempster-Shafer Based State Transition Rules
- 476 Downloads
Finite state impedance (FSI) control is a widely used approach to control active-transfemoral prostheses (ATP). Current design of state transition rules depends on hard thresholding of intrinsic mechanical measurements, which cannot cope well with uncertainty related with intra- and inter-subject variations of these intrinsic recordings. In this study, we aimed to generate more robust FSI control of ATP against these variations by using Dempster-Shafer theory (DST)-based transition rules. The FSI control with DST-based rules was implemented on an instrumented ATP, evaluated on five able-bodied subjects and one patient with a unilateral transfemoral amputation. Then the DSP based transition rules were compared to the control with hard threshold (HT)-based transition rules. The results showed that when compared to the hard thresholding approach, the DST yielded enhanced accuracy in state transition timing and reduced control errors when intra- and inter-subject variations were presented. Additionally, the parameters of DST-based rules were uniform for all the subjects tested, allowing for easy and efficient transition rule design and calibration. The outcome of this study can lead to further improvement of robust, practical, and self-contained ATP design, which in turn will advance the motor function of patients with lower limb amputations.
KeywordsImpedance control Finite state machine Uncertainty Amputee gait
Unable to display preview. Download preview PDF.
- 8.Aaron, R.K., Herr, H.M., Ciombor, D.M., Hochberg, L.R., Donoghue, J.P., Briant, C.L., Morgan, J.R., Ehrlich, M.G.: Horizons in prosthesis development for the restoration of limb function. J. Am. Acad. Orthop. Surg. 14(10), 198–204 (2006)Google Scholar
- 9.Lambrecht, B.G.A., Kazerooni, H.: Design of a semiactive knee prosthesis. In: IEEE International Conference on Robotics and Automation, 2009. ICRA ’09, pp. 639–645, 12–17 May 2009Google Scholar
- 11.Borjian, R., Lim, J., Khamesee, M.B., Melek, W.: The design of an intelligent mechanical active prosthetic knee. In: Industrial Electronics, 2008. IECON 2008. 34th Annual Conference of IEEE, pp. 3016–3021, 10–13 Nov 2008Google Scholar
- 12.Donath, M.: Proportional EMG Control for Above-Knee Prosthesis. MIT Press, Cambridge (1974)Google Scholar
- 16.Yeung, L.F., Leung, A.K., Zhang, M., Lee, W.C.: Long-distance walking effects on trans-tibial amputees compensatory gait patterns and implications on prosthetic designs and training. Gait Posture 35(2) (2011)Google Scholar
- 24.Sup, F.C.: A Powered Self-Contianed Knee and Ankle Prosthesis for Near Normal Gait in Transfemoral Amputees. Vanderbilt University (2009)Google Scholar
- 25.Perry, J., Burnfield, J.M.: Gait Analysis: Normal and Pathological Function, 2nd edn. SLACK, Thorofare (2010)Google Scholar
- 30.Sentz, K., Ferson, S.: Combination of Evidence in Dempster-Shafer Theory. In: vol. SAND2002-0835. Sandia National Laboratories (2002)Google Scholar
- 32.Chen, Q., Aickelin, U.: Anomaly detection using the Dempster-Shafer method. In: DMIN06, International Conference on Data Mining 2006, pp. 232–240, Las Vegas, Nevada, USA, 26–29 June 2006Google Scholar