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. 2009:5209582:645-651.
doi: 10.1109/ICORR.2009.5209582.

Powered Sit-to-Stand and Assistive Stand-to-Sit Framework for a Powered Transfemoral Prosthesis

Huseyin Atakan Varol  1 , Frank Sup, Michael Goldfarb
Affiliations

Powered Sit-to-Stand and Assistive Stand-to-Sit Framework for a Powered Transfemoral Prosthesis

Huseyin Atakan Varol et al. IEEE Int Conf Rehabil Robot. 2009.

Abstract

This work extends the three level powered knee and ankle prosthesis control framework previously developed by the authors by adding sitting mode. A middle level finite state based impedance controller is designed to accommodate sitting, sit-to-stand and stand-to-sit transitions. Moreover, a high level Gaussian Mixture Model based intent recognizer is developed to distinguish between standing and sitting modes and switch the middle level controllers accordingly. Experimental results with unilateral transfemoral amputee subject show that sitting down and standing up intent can be inferred from the prosthesis sensor signals by the intent recognizer. Furthermore, it is demonstrated that the prosthesis generates net active power of 50 W during standing up and dissipates up to 50 W of power during stand-to-sit transition at the knee joint.

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Figures

Fig. 1
Fig. 1
The self-contained powered knee and ankle transfemoral prosthesis.
Fig. 2
Fig. 2
Powered prosthesis control architecture.
Fig. 3
Fig. 3
The state chart depicting the phase transitions in standing and sitting modes.
Fig. 4
Fig. 4
Knee angle modulated knee stiffness during sit-to-stand and stand-to-sit phases.
Fig. 5
Fig. 5
Gaussian Mixture Model surface plots of the standing and sitting modes showing the regions of the feature space, where the probability density function is greater than 0.05, for the three dimensional PCA reduced data.
Fig. 6
Fig. 6
Prosthetic knee angle (top) and the real-time activity mode switching (bottom) for a 90 seconds standing and sitting trial.
Fig. 7
Fig. 7
Knee and ankle angles (top), torques (middle) and powers (bottom) during sitting down.
Fig. 8
Fig. 8
Knee and ankle angles (top), torques (middle) and powers (bottom) during standing up.
Fig. 9
Fig. 9
Video frames of standing up (a) and sitting down (b) transitions.
See this image and copyright information in PMC

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