LAUSR

Abstract The rotary encoder is an important sensor for measuring rotational motion. A step–stress accelerated degradation test (SSADT) is conducted with respect to accuracy to evaluate the reliability rapidly. The existing errors in output signals are identified as degradation indicator to characterize performance degradation. A methodology for the encoder SSADT modeling is presented. Wiener process theory with unit–to–unit variation is utilized in the model to describe the degradation process of each error. Considering the correlation among the degradation processes, a multivariate degradation modeling method is developed based on the Copula function to estimate the reliability of rotary encoder with multiple degradation indicators. The reliability of the encoder under the use–stress level is derived by combining the margin distributions and Copula function.