A Time-Discrete Haptic Feedback System for Use by Persons with Lower-Limb Prostheses During Gait.

Persons with lower-limb amputations experience limited tactile knowledge of their prostheses due to the loss of sensory function from their limb. This sensory deficiency has been shown to contribute to improper gait kinematics and impaired balance. A novel haptic feedback system has been developed to address this problem by providing the user with center of pressure information in real-time. Five piezoresistive force sensors were adhered to an insole corresponding to critical contact points of the foot. A microcontroller used force data from the insole to calculate the center of pressure, and drive four vibrotactile pancake motors worn in a neoprene sleeve on the medial thigh. Center of pressure information was mapped spatially from the plantar surface of the foot to the medial thigh. Human perceptual testing was conducted to determine the efficacy of the proposed haptic display in conveying gait information to the user. Thirteen able-bodied subjects wearing the haptic sleeve were able to identify differences in the speed of step patterns and to classify full or partial patterns with (92.3 ± 2.6)% and (94.9 ± 2.1)% accuracy respectively. The results suggest that the system was effective in communicating center of pressure information through vibrotactile feedback.