Towards transfers in paraplegia assisted by electrical stimulation and inertial system

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.