McKibben muscles are pneumatic actuators that have potential application in the rehabilitation of persons with physical impairments. These actuators have been known to exhibit similarities in human musculoskeletal systems. In order to better understand and improve the closed - loop control of these pneumatic muscles, a physical joint model was constructed with an agonist and an antagonist muscle operating under non-linear control. With the use of LabVIEW software, compliant McKibben air muscles and Flock-of-Birds sensor, the author was able to implement and compare a standard bang-bang controller and experimental non-linear digital Proportional (P) controller. The feedback mechanism is based on the input given from Flock-of-Birds sensor to achieve a desired position.

The results show the expected instability of the bang-bang controller, and confirm the superiority of the non-linear proportional method in achieving rapid and smooth movement of the joint from one target position to the next.