Linear dynamometer testing of hydraulic artificial muscles with variable recruitment

A novel, meso-scale hydraulic actuator characterization test platform, termed a linear hydraulic actuator characterization device, is demonstrated and characterized in this study. The linear hydraulic actuator characterization device is applied to testing McKibben artificial muscles and is used to show the energy savings due to the implementation of a variable recruitment muscle control scheme. The linear hydraulic actuator characterization device is a hydraulic linear dynamometer that can be controlled to enable a desired force and stroke profile to be prescribed to the artificial muscles. The linear hydraulic actuator characterization device consists of a drive actuator that is connected in series with the test muscles. Thus, the drive cylinder can act as a controlled disturbance to the artificial muscles to simulate various loading conditions. With the ability to control the loading conditions of the artificial muscles, the linear hydraulic actuator characterization device offers the ability to experimentally validate the muscles' performance and energetic characteristics. For instance, the McKibben muscles' quasi-static force-stroke capabilities, as well as the power savings of a variable recruitment control scheme, are measured and presented in this work. Moreover, the development and fabrication of this highly versatile characterization test platform for hydraulic actuators is described in this article, and the characterization test results and efficiency study results are presented.