Pseudo-proprioceptive motion feedback by electric stimulation

This paper proposes a pseudo-proprioceptive motion feedback system by using electric stimulation for paraplegic patients to sense walking motions states. A wearable-type controller is developed for them to control an exoskeleton that physically supports lower limbs´ motion to walk. The patients lost his sensation on the lower limbs and cannot know a current lower limbs´ state due to loss of their somatosensory feedback. Patients who use the walking support system frequently check state of their lower limbs by sight. As a result, they cannot look forward during walking. The purpose of our study is to inform the lower limbs´ state without any visual contact. This paper proposes a tactile feedback system that conveys the lower limb´s posture using an electric stimulation. Some preliminary experiments are executed to measure capabilities of healthy people with normal proprioceptive feedback and with the substitute feedback using the electric stimulation in terms of resolution and time delay of the hip joint angle, and limitation of sensitivity of inertia change. Our developed feedback system achieved the same performance on joint angle precision and time delay. As far the sensitivity of inertia change, the substitute feedback could not have equivalent performance to sensitivity of the healthy humans.