The Research Of A New Human Motion Measurement System’s Measuring Range And Accuracy

With the rapid development of science and technology, the researchabout the laws of human motion becomes more and more profound both inthe fields of medical and sports. Human motion measurement has importantapplications in the field of modern sports, human medical rehabilitation,humanoid robots, film and television animation and virtual reality etc.,therefore, it is important to carry out the study of human motionmeasurement.This paper has established a new human motion measurement systemwhich is a cable-based parallel mechanism for determining the movementparameters of human body, those parameters include pose, movingtrajectory, displacement, velocity, acceleration, angular displacement,angular velocity, angular acceleration and so on. Compared with theexisting human motion measurement products, the proposed measuringsystem has the following advantages: low cost, a small amount of data andthe simple procedure of processing, strong anti–interference, and real-timemeasurement.The content and innovations of the research:Measurement system’s hardware and software platforms had beendesigned, which are helpful for computing and gathering human motiondata. Taking servo motor instead of the cable sensor as the measuring device,so that the tension of the cable is controllable, what is more, this system cannot only meet the above measurement function, but also make the cable as an active system, which can drive the moving platform in a designatedtrajectory. The traditional cable-based measurement system cannot get thisfunction.In order to solve the problem of the kinematics and dynamics ofmeasurement system, this paper takes the human motion measurement unitas the candidate of research. Newton-Euler method is applied to analyzethe moving platform. So that we get the equations of dynamics which aredescribed the relationship of force and acceleration, torque and angularacceleration. Finally, given the dynamical equations and cables’ specialconditions, we get the reachable workspace of platform.At present, the research on the cable-based parallel measurementsystem is limited. In order to calculate the measuring workspace ofmeasurement system, this paper describes in detail four conditions whichrestrain the movement of platform, i.e., cable to cable collision, cable tomoving platform collision, limitation of cable length, compatibilityconstraint. And then use these algorithms for solving the position workspaceand orientation workspace of the moving platform. At last, we get theworkspace of the human motion measurement unit.Given the established measurement platform, the sources of error arestudied in detail, installing the pulleys on the winding device which canavoid the winding error of cable. and make use of statistical methods todesign the mathematical model of measurement error, and the mathematicalreasoning is used for getting the relationship between the pose error andcable’s length measurement error.We have established the human motion measurement system to carryout human motion measurement experiment to measure the human arm posein3D space, such as Euler angles and velocity. These results prove thecorrectness of former deduction. In fact, the human motion measurementunit is also regarded as a cable-based parallel mechanism, therefore, themathematical model of human motion measurement unit, such as thecalculation of the workspace, kinematics and dynamics analysis are also of significant for the study of cable robot.