Dehe Cui

Publication Date


Document Type


First Advisor

Azadivar, Farhad, 1948-

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Industrial Engineering


Robots--Motion--Effect of joint position errors on--Analysis; Robots; Industrial


In order for an industrial robot to perform a particular manufacturing process, its end-effector must be positioned and oriented correctly with respect to the job. Their positions and orientations are achieved by commanding the robot's joint to assume certain angles and/or displacements. However, due to position errors at the joints, the assumed positions are almost always different from those commanded. These deviations induce a random error to the position and orientation of the hand. The ability of the hand to perform according to the required accuracy depends, among other things, on the extent of joint position errors. The objective of this thesis is to provide an experimental method of estimating the random joint position errors to be used in evaluation of the performance of robot manipulators. A method is presented for obtaining the true characteristics of the random joint position errors. The method is based on the single-joint rotation tests. Each joint is individually moved to a position and then the hand location and orientation are accurately measured. In order to eliminate the coupling effects of the joint position errors, a teaching method is used to make the random errors in joints independent of each other. These random joint position errors are experimentally determined for a PUMA 560 six-joint manipulator. The results of the measurement show that these errors are functions of the joint displacements and the robot operation speeds. The effect of the random joint position errors on the accuracy of the point-to-point operation is studied by using the measured data. An example of the effect of these errors of the robot manipulator on its performance in a special class of manufacturing operation is presented to show how the robot motion speeds and joint displacements affect the accuracy of the robot. In addition, an example is presented for determining the optimum operation speed of a robot in terms of maximum productivity in a given manufacturing situation.


Includes bibliographical references (pages [87]-90)


ix, 90 pages




Northern Illinois University

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