  The hybridisation of robot-assisted gait training and functional electrical
stimulation (FES) can provide numerous physiological benefits to neurological
patients. However, the design of an effective hybrid controller poses
significant challenges. In this over-actuated system, it is extremely difficult
to find the right balance between robotic assistance and FES that will provide
personalised assistance, prevent muscle fatigue and encourage the patient's
active participation in order to accelerate recovery. In this paper, we present
an adaptive hybrid robot-FES controller to do this and enable the triadic
collaboration between the patient, the robot and FES. A patient-driven
controller is designed where the voluntary movement of the patient is
prioritised and assistance is provided using FES and the robot in a
hierarchical order depending on the patient's performance and their muscles'
fitness. The performance of this hybrid adaptive controller is tested in
simulation and on one healthy subject. Our results indicate an increase in
tracking performance with lower overall assistance, and less muscle fatigue
when the hybrid adaptive controller is used, compared to its non adaptive
equivalent. This suggests that our hybrid adaptive controller may be able to
adapt to the behaviour of the user to provide assistance as needed and prevent
the early termination of physical therapy due to muscle fatigue.
