Modeling and Verification of an Astronaut Handling Large-mass Payload

Abstract

The experiments on astronaut motions are difficult to conduct due to the limitation and high cost of constructing or simulating the microgravity environment of space. Therefore, the method of computer simulation on astronaut extravehicular activity is broadly promoted. However, validations and verifications for these simulations stated in related literatures are incomplete such as comparing with the limits of human body movements or reconstructing a three-dimensional movement for some parts of EVA video. Novel modeling and verification methods for the task of an astronaut handling large-mass payload during EVA were revealed. A simplified model of an astronaut was constructed, and the astronaut motion was conceived as a planar movement of a multi-body system which includes seven segments with six revolute joints in the human body sagittal plane. The inverse kinematics method was used to calculate joint angles, joint velocities, and joint accelerations in time domain. The solution of joint torques using the inverse recursive dynamics was achieved. Furthermore, a virtual model with the ADAMSTM software was developed and implemented to verify the results by adding the kinematical data calculated to joints in order to achieve the trace of the center of mass of the hand. Additionally, the joints kinematics and kinetics data with time in the virtual model were obtained and compared with the corresponding calculated data. This result indicates that the modeling methods proposed can be employed as a solid algorithm to conduct the simulation of astronaut’s tasks in EVA, and verification using the virtual model can be easily operated and has a good accuracy. This study provides an effective and economical way of modeling and simulation for extravehicular missions.