A Time-Discrete Haptic Feedback System for People with Lower-Limb Prostheses

People with lower-limb prostheses experience limited tactile and perceptual knowledge of their prosthetic limbs. This has been shown to contribute to improper gait kinematics, impaired balance, and musculoskeletal disorders. This work presents a novel haptic feedback system that aims to provide real-time augmented sensory feedback to people with lower-limb prostheses. The system consists of an insole with piezoresistive force sensors, a microcontroller, and a vibrotactile thigh sleeve with four pancake motors. Force data from the insole are used to calculate the plantar center of pressure, and changes in the center of pressure are then presented to the user as time-discrete vibrations on the medial thigh. Human perceptual testing was conducted to determine the efficacy of the proposed haptic display in conveying gait information to users. Thirteen able-bodied participants wearing the haptic sleeve were able to accurately identify differences in the speed of step patterns (92.3%) and to classify full or partial patterns (94.9%). These results suggest that the system was effective in communicating center of pressure information through vibrotactile feedback.