Hydraulic artificial muscles

This article presents hydraulic artificial muscles as a viable alternative to pneumatic artificial muscles. Despite the actuation mechanism being similar to its pneumatic counterpart, hydraulic artificial muscles have not been widely studied. Hydraulic artificial muscles offer all the same advantages of pneumatic artificial muscles, such as compliance, light weight, low maintenance, and low cost, when compared to traditional fluidic cylinder actuators. Muscle characterization in isometric and isobaric conditions are discussed and compared to pneumatic artificial muscles. A quasi-static model incorporating the effect of mesh angle, friction, and muscle volume change throughout actuation is presented. This article also discusses the use of hydraulic artificial muscles for low-pressure hydraulic mesoscale robotic leg.