Experimental test data for hydraulic/pneumatic muscle operation
McKibben muscles have been shown to have improved stiffness characteristics when operating hydraulically. However, when operating pneumatically they are compliant and so have potential for safer physical Human Robot Interaction (pHRI). This research explored a method for rapidly switching between pneumatic and hydraulic modes of operation without the need to remove all hydraulic fluid from the actuator. These data were obtained from experiments performed on a single McKibben muscle acting on a load with gravity providing a restoring force. The data show the results obtained when applying step and sinusoidal control inputs to a McKibben muscle when operating both pneumatically and hydraulically. The graphs show the difference in behaviour in the two operating modes. The experimental data also show how the muscles react to disturbance loads and how a damping effect is produced as a result of the hydraulic mode of operation.