While most take their ability to walk for granted, some are unable to walk secondary to any number of pathologies, such as traumatic brain injury (TBI), spinal cord injury (SCI), cerebrovascular accidents (CVA), cerebral palsy (CP), multiple sclerosis (MS), Parkinson's disease, as well as various orthopedic conditions. Decreased activity has been shown to be associated with rapidly deconditioning and other co-morbidities. Rehabilitation techniques that afford patients the ability to begin reconditioning through walking sooner may ultimately enhance their return to a better quality of life.

The overall goal of this study is to design a gait generation mechanism for rehabilitation of paralyzed legs. This mechanism should provide an appropriate afferent input to the spinal cord by moving the legs in a physiological way.

This thesis focuses on the dimensional synthesis of a four-bar linkage to reproduce the desired ankle trajectory in the sagittal plane.

The data of sagittal flexion/extension at the hip and knee joints from healthy people are used to define the desired ankle trajectory during normal gait cycle. A path generation four-bar mechanism is then synthesized to obtain proper link and coupler dimensions. The resulted coupler curve matches well with the desired ankle trajectory.