  Recently, robot assisted therapy devices are increasingly used for spinal
cord injury (SCI) rehabilitation in assisting handicapped patients to regain
their impaired movements. Assistive robotic systems may not be able to cure or
fully compensate impairments, but it should be able to assist certain impaired
functions and ease movements. In this study, a couple control model for
lower-limb orthosis of a body weight support gait training system is proposed.
The developed leg orthosis implements the use of pneumatic artificial muscle as
an actuation system. The pneumatic muscle was arranged antagonistically to form
two pair of mono-articular muscles (i.e., hip and knee joints), and a pair of
bi-articular actuators (i.e., rectus femoris and hamstring). The results of the
proposed couple control model showed that, it was able to simultaneously
control the antagonistic mono- and bi-articular actuators and sufficiently
performed walking motion of the leg orthosis.
