Control Method for Power Assisted Cart Using Walking Effect Prediction Aimed at Improvement of Load Reduction Ratio
Norihiro Kobayashi and Takayuki Tanaka
Graduate School of Information Science and Technology, Hokkaido University, Kita 14, Nishi 9, Kita-ku, Sapporo, Hokkaido 060-0814, Japan
In previous work, we proposed controlling powerassisted carts by using a motor torque limiter that achieves the desired load-reduction ratio even if torque saturates. We assumed, however, that the operator accelerates smoothly up to the target speed, so that when velocity is affected largely by the input force of walking, prediction error becomes large and the target load reduction ratio was not achieved. To solve this problem, we propose an improving the achievement rate of the target load reduction ratio in two steps, first, by predicting the number of steps toward target speed from initial input and, second, by switching the prediction model. We use cart input force and speed to predict operator acceleration patterns. Our proposal predicts operator needs and delivers the desired loadreduction ratio by predicting operation. Results show that the achievement rate of the target load-reduction ratio is improved by using our proposed control. In other words, applying our proposal improves the short available time of power-assisted carts.
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