Towards transfers in paraplegia assisted by electrical stimulation and inertial system

Abstract

Spinal cord injured (SCI) patients that have no lower limb motor function perform several transfers during a day. Those transfers are from and to a wheelchair, a car, a hygienic chair, among other situations. These repetitive motions can cause overload on their upper limbs over time. Functional Electrical Stimulation may be used to induce contraction on knee extensors, providing additional support at the joint level during transfer. However, the design of the interface with which to control the onset of stimulation is challenging. The use of some automated system is beneficial, particularly since the user is using both hands to perform the transfer. Therefore, the precise moment of activation is important because, if erroneous, it can cause the user's loss of balance. A system with which the users themselves can activate the stimulation with triggers in gloves is used to collect kinematic data from SCI patients during Sitting Pivot Transfers. The results show that the trunk angle can be used along a threshold for a reliable assistance device. Strategies for portability using a wireless inertial measurement unit are also discussed.

A Residual Movement Classification Based User Interface for Control of Assistive Devices by Persons With Complete Tetraplegia

“…The literature focusing on individuals with SCI is scarce when compared to the one related to amputees. IMUs have been used to track trunk angle as input to trigger Functional Electrical Stimulation (FES) for lower limb assistance in Sit to Stand [29] and Sitting-Pivot [30] Transfers in individuals with paraplegia. They both showed upper body kinematics can successfully trigger FES and decrease the load on upper limbs when performing these activities.…”