面向速度适应的动力小腿假肢蹬地时刻在线识别

The paper investigates the on-line recognition of push-off for an amputee who wears powered prosthesis at different speeds. In the experiment, the subject wears the powered prosthesis designed by our research group. The angular sensor integrated in the prosthesis measures the ankle angle of prosthesis. The moment corresponding to the maximum ankle angle is the moment of push-off. We divide one stride into two modes (mode 1 to mode 2) based on ankle angle (the transition moment from mode 1 to mode 2 is the push-off moment). Two inertial measurement units and a capacitance sensing system are used to recognize the two locomotion modes and push-off. We first collect the walking data that the subject walks on treadmill at the speed of 0.9 m/s to train model, then carry out the research based on the model under different speeds (0.7, 0.9, 1.1 m/s). Under different speeds, on-line real-time recognition accuracies are 97.59%, 98.17% and 93.39%, respectively. Besides, specific push-off in one stride could be recognized with no error. There is time delay between the recognition result of push-off and the real push-off of the powered prosthesis, which appears in advance or behind (corresponding to 1.5±8.75 ms, -12.38±5.39 ms, -29.52±15.64 ms). The results suggest that the method of mode recognition is efficient and feasible to recognize push-off with high accuracy and short delay, which shows good speed adaptability.