Development Of Measuring Arm For EVA Spacesuit Operational Ability

In the field of manned spaceflight, extravehicular spacesuit is the essential equipment in extravehicular activity (EVA). EVA spacesuit not only provides life support for astronaut, but also should have a high activity performance. So the astronaut can finish all kinds of extravehicular work. It is an ergonomics problem. The measuring of reachable region and operational limit region of EVA spacesuit are the key points in spacesuit ergonomics. This thesis developed a measuring arm system for EVA spacesuit operational ability, which can measure the reachable region and operational limit region, provides an important tool for the study of EVA spacesuit. The following work has been done in this thesis:According to the measuring requirements of the reachable region and operational limit region of EVA spacesuit, three design schemes are presented by analyzing the character of perpendicular coordinate measuring machines (CMM) and articulated arm CMM. The plane rotating arm is chosen as the system scheme by comparing the three design schemes. The joint numbers and length of arm is determined by studying the measuring space of plane rotating arm and the attitude of terminal articulated arm.Based on the theory of homogeneous transformation and DH method in robot kinematics, the coordinate measuring model of articulated arm system is established, the system measuring space is given.Mechanical structure design of measuring arm system is carried out, including the designs of elevating system, articulated arm system and mechanical measuring unit. Some important elements of measuring equipment are selected by calculation, strength and rigidity check of some key components and parts are carried out, which ensures the measuring equipment's security and reliability.Electrical and software design of the measuring arm system are carried out, key studies are the realization of servo motor position control and a number of sensors data acquisition. The software was developed by VC++, it realized 3-d image display, graphic interaction, and data report generation. An algorithm of data processing was presented, and its effectiveness has been validated by calibration.Experimental studies of measuring system are carried out, and main errors of coordinate measurement are comprehensively analyzed, among them the systematic error sources and random error sources are the key points. According to the model of system, error model was constructed by partial differentiation. This linear deviation model represents the connection between coordinate errors and structure parameters. Based on the error model of system, measurement error of single point has been analyzed by computer simulation.The measuring arm for EVA spacesuit operational ability is successfully developed. This measuring equipment as an important tool for the study of EVA spacesuit not only filled up the domestic blank, but also provided reference for the development of similar CMM and promotes the coordinate measuring technology progress of China.