Abstract
This paper introduces a novel exoskeleton active walking assistance control framework based on frequency adaptive dynamics movement primitives (FADMPs). The FADMPs proposed in this paper is an online learning and prediction algorithm which is able to online estimate the fundamental frequency of human joint trajectory, learn the shape of joint trajectory and predict the future joint trajectory during walking. The proposed active walking assistance control framework based on FADMPs is a model-based controller which relies on the human joint torque estimation. The assistance torque provided by exoskeleton is estimated by human lower limb inverse dynamics model which is sensitive to the noise in the joint motion trajectory. To estimate a smooth joint torque profile, the joint motion trajectory must be filtered first by a lowpass filter. However, lowpass filter will introduce an inevitable phase delay in the filtered trajectory. Both simulations and experiments in this paper show that the phase delay has a significant effect on the performance of exoskeleton active assistance. The active assistant control framework based on FADMPs aims at improving the performance of active assistance control by compensating the phase delay. Both simulations and experiments on active walking assistance control show that the performance of active assistance control can be further improved when the phase delay in the filtered trajectory is compensated by FADMPs.
Highlights
Since the 1960s, the United States General Electric Company launched the world’s first full-body exoskeleton robot Hardiman (Mosher, 1967), exoskeleton robot has gradually became a hot research direction of robotics
This paper introduces an exoskeleton active walking assistance control framework based on frequency adaptive dynamics movement primitives (FADMPs)
The active walking assistance control framework based on FADMPs is able to provide a no-phase-delay assistance to the human joint during walking
Summary
Since the 1960s, the United States General Electric Company launched the world’s first full-body exoskeleton robot Hardiman (Mosher, 1967), exoskeleton robot has gradually became a hot research direction of robotics. Exoskeleton robot is a typical man-machine coordinated control system. The core of this system is the human who provides intelligent decision for the whole system. Exoskeleton provides power assistance for the human body. By combining human intelligence with the powerful assistance of the exoskeleton, the exoskeleton can accomplish some tasks that cannot be completed by the conventional robots, such as individual combat, disaster relief, and rehabilitation. After entering the 20th century, the progress of science and technology has promoted the rapid development of exoskeleton, and many research achievements have emerged
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