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. 2009;14(6):667-676.
doi: 10.1109/TMECH.2009.2032688.

Preliminary Evaluations of a Self-Contained Anthropomorphic Transfemoral Prosthesis

Frank Sup  1 , Huseyin Atakan Varol, Jason Mitchell, Thomas J Withrow, Michael Goldfarb
Affiliations

Preliminary Evaluations of a Self-Contained Anthropomorphic Transfemoral Prosthesis

Frank Sup et al. IEEE ASME Trans Mechatron. 2009.

Abstract

This paper presents a self-contained powered knee and ankle prosthesis, intended to enhance the mobility of transfemoral amputees. A finite-state based impedance control approach, previously developed by the authors, is used for the control of the prosthesis during walking and standing. Experiments on an amputee subject for level treadmill and overground walking are described. Knee and ankle joint angle, torque, and power data taken during walking experiments at various speeds demonstrate the ability of the prosthesis to provide a functional gait that is representative of normal gait biomechanics. Measurements from the battery during level overground walking indicate that the self-contained device can provide more than 4500 strides, or 9 km, of walking at a speed of 5.1 km/h between battery charges.

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Figures

Fig. 1
Fig. 1
Normal biomechanical gait data for an 85 kg subject walking at a cadence of 80 steps/min [9].
Fig. 2
Fig. 2
Self-contained powered knee and ankle transfemoral prosthesis: (left) front and (right) side views.
Fig. 3
Fig. 3
Reduction of linear force output required by the ankle motor unit by the addition of a spring in parallel for walking at 120 steps/min, taken from averaged normal biomechanical data [9]. Note that the spring is engaged at −5° and achieves a peak spring force of 620 N at 7°
Fig. 4
Fig. 4
Sagittal moment load cell: top and bottom views.
Fig. 5
Fig. 5
Sensorized prosthetic foot with and without strain gage covers.
Fig. 6
Fig. 6
Embedded system framework.
Fig. 7
Fig. 7
Embedded system hardware (left) with and (right) without servoamplifiers.
Fig. 8
Fig. 8
Complete control architecture showing high, middle, and low levels.
Fig. 9
Fig. 9
Finite-state machine for level walking. Blocks represent states and arrows represent the corresponding transitions.
Fig. 10
Fig. 10
Finite-state machine for level standing. Blocks represent states and arrows represent the corresponding transitions.
Fig. 11
Fig. 11
Unilateral transfemoral amputee test subject used for the powered prosthesis evaluation.
Fig. 12
Fig. 12
Measured joint angles of the powered prosthesis for ten consecutive gait cycles of treadmill walking at slow, normal, and fast cadences, 64, 75, and 86 steps/min, respectively.
Fig. 13
Fig. 13
Measured joint angles, torques, and powers of the powered prosthesis for ten consecutive gait cycles at self-selected speed (5.1 km/h at 87 steps/min).
Fig. 14
Fig. 14
References, and actual knee and ankle joint torques of the powered prosthesis for one stride at self-selected speed (5.1 km/h at 87 steps/min) on normal ground.
Fig. 15
Fig. 15
Measured electrical and mechanical power at the knee and ankle joints of the powered prosthesis over one gait cycle at self-selected speed (5.1 km/h at 87 steps/min) on normal ground.
Fig. 16
Fig. 16
Average electrical power consumption of the powered prosthesis for standing and walking at self-selected speed (5.1 km/h at 87 steps/min) on normal ground.
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References

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