| World wide, millions of people enter a rehabilitation program with the goal to relearn lost walking abilities due to an incident such as a stroke or an spinal cord injury. A very promising rehabilitation technique is Partial Body Weight Supported (PBWS) stepping on a treadmill. The repeated motion (sometimes assisted by a physical therapist) of the legs stimulates the neurological motor control centers. The support force provided by an unloading device reduces the burden on the often weak patient and allows for increased walking and training periods. In some cases, patients unable to walk may use the PBWS device to walk.; An active PBWS device which is equipped with an actuator and sensors has been constructed. This prototype is capable of tracking an unloading reference force relatively precisely. There are strong indications that with appropriate unloading force modulations and the resulting enlarged range of lower extremity motion, the neuromuscular stimulation can be increased such that a superior rehabilitation outcome can be expected.; This dissertation describes the control aspects of the active PBWS device. First, a mathematical model is derived that describes the dynamic behavior of the system with a person in a body support harness. The model provides the foundation for the design of appropriate feedback control laws. Several output regulation control algorithms are evaluated by simulation and testing with the prototype. In particular, a robust controller, tolerating plant model uncertainties as well as an adaptive controller with the ability to tune to an unknown walking speed are among the developed algorithms.; The PBWS rehabilitation prototype is found suitable to provide constant and gait-synchronous modulated unloading body weight forces. Preliminary tests and biomechanical motion analysis of the gait kinematics demonstrate the desired gait parameter changes and an increase in the range of lower extremity motion. The device enables clinical studies that probably will result in better gait rehabilitation in the future. |
