Combining a Bio-Inspired Reflexive Neuromuscular Controller with a Trajectory Controller for Active Lower-Extremity Gait-Assistive Devices

Active gait-assistive devices have the potential to drastically increase quality of life for patients with various diseases affecting mobility, but more research in control methods is needed to create seamless interaction with patients. The golden standard of control for these devices, trajectory control, has the advantage of being simple and predictable but lacks the ability to react to changes in the environment or changes in patient movement. A reflex-based neuromuscular model shows interesting similarities with real human gait, and shows potential as a new control method for these devices. However, the reflex-based controller requires movement as input to output useful assistance and it can react unexpectedly when it is in a situation it was not optimized for. Therefore, both control types are combined to make use of the advantages of both. In this work a feasibility study is conducted with one spinal cord injury patient with full paraplegia of the legs with a trajectory controller implemented on hip and knee and a combined controller on the ankle joint. We found that the patient was able to walk semi-independently using this method and the patient indicated a preference for the combined method over the pure trajectory based controller. Overall, a novel method of control for prosthetic and orthotic devices is shown and implemented and its feasibility is demonstrated with a gait impaired SCI subject.