Improving postural stability among people with lower-limb amputations by tactile sensory substitution

Journal of NeuroEngineering and Rehabilitation

Baojun Chen¹  Yanggang Feng¹  Qining Wang¹  Lijun Chen²  Kunlin Wei³ 

[1] Department of Advanced Manufacturing and Robotics, College of Engineering, Peking University, Beijing, China;School of Psychological and Cognitive Sciences, Peking University, 5 Yiheyuan Road, 100871, Beijing, China;Beijing Key Laboratory of Behavior and Mental Health, Beijing, China;School of Psychological and Cognitive Sciences, Peking University, 5 Yiheyuan Road, 100871, Beijing, China;Beijing Key Laboratory of Behavior and Mental Health, Beijing, China;Key Laboratory of Machine Perception, Ministry of Education, Beijing, China;Peking-Tsinghua Center for Life Sciences, Beijing, China;

关键词: Sensory substitution;    Lower-limb amputation;    Postural control;    Intelligent prosthesis;   

DOI  :  10.1186/s12984-021-00952-x

来源: Springer

【 摘 要 】

BackgroundFor people with lower-limb amputations, wearing a prosthetic limb helps restore their motor abilities for daily activities. However, the prosthesis's potential benefits are hindered by limited somatosensory feedback from the affected limb and its prosthesis. Previous studies have examined various sensory substitution systems to alleviate this problem; the prominent approach is to convert foot–ground interaction to tactile stimulations. However, positive outcomes for improving their postural stability are still rare. We hypothesized that the sensory substiution system based on surrogated tactile stimulus is capable of improving the standing stability among people with lower-limb amputations.MethodsWe designed a wearable device consisting of four pressure sensors and two vibrators and tested it among people with unilateral transtibial amputations (n = 7) and non-disabled participants (n = 8). The real-time measurements of foot pressure were fused into a single representation of foot–ground interaction force, which was encoded by varying vibration intensity of the two vibrators attached to the participants’ forearm. The vibration intensity followed a logarithmic function of the force representation, in keeping with principles of tactile psychophysics. The participants were tested with a classical postural stability task in which visual disturbances perturbed their quiet standing.ResultsWith a brief familiarization of the system, the participants exhibited better postural stability against visual disturbances when switching on sensory substitution than without. The body sway was substantially reduced, as shown in head movements and excursions of the center of pressure. The improvement was present for both groups of participants and was particularly pronounced in more challenging conditions with larger visual disturbances.ConclusionsSubstituting otherwise missing foot pressure feedback with vibrotactile signals can improve postural stability for people with lower-limb amputations. The design of the mapping between the foot–ground interaction force and the tactile signals is essential for the user to utilize the surrogated tactile signals for postural control, especially for situations that their postural control is challenged.

【 授权许可】

CC BY