Angular measurement of high precision reducer for industrial robot

High precision reducer is the core component of industrial robot. Its performance test is the key to improve product quality and ensure the accuracy of robot operation. One of the basic geometric parameters in performance test is the angle, which refers to the angular displacement of the input or output of the tested reducer. Based on a vertical instrument, angular measurement systems are designed in this paper. In order to ensure the precision of results, the angle encoder is as close as possible to the measured object, which shortens the measurement chain and reduces the number of error sources. A cylindrical and disc structure improves the structural stiffness and minimizes the angular errors caused by weak stiffness supports in conventional instrument. Another system consisting of an autocollimator and a regular polyhedron, whose output is taken as angular standard, calibrates absolute circular gratings in the instrument. The model based on Back Propagation (BP) neural network can compensate the error over the whole circumference, and finally get the angular displacement of input and output of the tested reducer in the drive process accurately. After compensation, the angular measurement errors of the instrument are within ± 2 arc seconds.