Tenodesis Grasp Emulator: Kinematic Assessment of Wrist-Driven Orthotic Control
This work addresses mobility issues for people with C6-7 spinal cord injury, but it is incremental as it builds on existing orthotic control strategies.
The study tackled the problem of kinematic constraints in wrist-driven orthotics for spinal cord injury patients by using a Tenodesis Grasp Emulator to assess body compensation during grasp-and-release tasks, finding significant compensation in constrained modes and suggesting that flexible control schemes could reduce it.
Wrist-driven orthotics have been designed to assist people with C6-7 spinal cord injury, however, the kinematic constraint imposed by such a control strategy can impede mobility and lead to abnormal body motion. This study characterizes body compensation using the novel Tenodesis Grasp Emulator, an adaptor orthotic that allows for the investigation of tenodesis grasping in subjects with unimpaired hand function. Subjects perform a series of grasp-and-release tasks in order to compare normal (test control) and constrained wrist-driven modes, showing significant compensation as a result of the constraint. A motor-augmented mode is also compared against traditional wrist-driven operation, to explore the potential role of hybrid human-robot control. We find that both the passive wrist-driven and motor-augmented modes fulfill different roles throughout various tasks tested. Thus, we conclude that a flexible control scheme that can alter intervention based on the task at hand holds the potential to reduce compensation in future work.