The use of artificial muscles in space suit simulation for partial gravity experimentation and training

The Aurora/MIT project team has developed a knee joint prototype for a space suit simulator that is designed to be lower weight and form-factor than previous simulators, while mimicking the resistive properties to human motion that pressurized space suits necessarily impose. Specifically, we employed “artificial muscle” pneumatic actuators to actively control the joint torques for any given limb angle, in order to closely reproduce the nonlinear hysteretic relationship and also allow for tuning of the joint to mimic any space suit design. For this initial feasibility study, we tested the prototype on MIT´s Robotic Space Suit Tester (RSST) with an example control scheme, intended to emulate NASA´s Extravehicular Mobility Unit (EMU) space suit. Testing indicated that the torque-vs.-angle relationship of the prototype knee mimics that of the EMU knee with 15%, ranging from -12 to 25 Nm (the EMU torque range is -8 to 29 Nm). Results from this preliminary design and the associated testing suggest that a full-body actively-controlled space suit simulator may accurately emulate the properties of multiple space suits.