Wearable CMG design for the Variable Vector Countermeasure Suit

The Variable Vector Countermeasure Suit (V2Suit) is a countermeasure suit for sensorimotor adaptation and musculoskeletal deconditioning in microgravity. The V2Suit consists of wearable modules containing arrays of control moment gyroscopes (CMGs) that provide a viscous resistance to motions made against a specified direction. To reduce the movement coordination and sensorimotor problems seen during and following gravity level transitions, this resistance will be felt in the direction of "down" to mimic gravity. Control moment gyroscopes are commonly used for spacecraft stabilization. The V2Suit uses a miniaturized CMG array in a body-worn system to apply torque to the wearer\´s musculoskeletal joints. Miniaturizing a CMG array while still generating enough gyroscopic torque for suitable resistance is a main challenge in the design of the V2Suit system. The initial specification for the torque magnitude output was set to 0.1 Nm. Various candidate CMG arrays were analyzed to determine the appropriate architecture for the array inside a V2Suit module, as well as flywheel parameters for the chosen array. The selected array is a 4 CMG pyramid array, chosen for a combination of torque output performance and size and hardware considerations. A mechanical design for the V2Suit 4 CMG pyramid array was developed using a combination of off the shelf and custom manufactured components. Minimizing the size of the array drove many design decisions; the final module design has a 6.5 inch square footprint and is 3.5 inches tall. A brass board prototype has been fabricated based on this design.