The Variable Vector Countermeasure Suit for space habitation and exploration

Abstract

The Variable Vector Countermeasure Suit (V2Suit) is a countermeasure suit for sensorimotor adaptation and musculoskeletal deconditioning in microgravity. The V2suit will consist of modules containing arrays of control moment gyroscopes (CMGs) which will be controlled to provide viscous resistance to motion against a specified direction. To reduce the coordination and sensorimotor problems seen during and following gravity level transitions, this resistance will be felt in the direction of "down" to mimic gravity. In microgravity, visual cues are dominant for orientation perception and one's perceived direction of "down" may change for a variety of reasons. The resistance felt by the V2suit wearer is a gyroscopic torque vector perpendicular to the direction of "down"; in order to send appropriate motor control commands the user's perceived direction of "down" must be known throughout use. Algorithms have been developed to enable the user to initialize a direction of "down" track this direction (as well as the module orientation and other relevant information) throughout operation. Control moment gyroscopes are commonly used for spacecraft stabilization. The V2Suit aims to miniaturize a CMG array for use inside wearable modules mounted on body segments. A trade study was conducted, analyzing various candidate CMG arrays to determine the appropriate architecture for the array inside a V2Suit module. The selected array is a 4 CMG pyramid array, chosen for a combination of torque output performance and size and hardware considerations. A detailed mechanical design for the V2Suit CMG array has been developed for the production of a brassboard prototype unit. Steering laws for singularity avoidance and resetting the gimbal angles have been presented, and will be tested with the brassboard unit. Additionally, a proposed method for measuring torque output from the unit has been presented.