Analysis of Randomness for Motion Error of Function Generation Mechanisms

The motion error of function generation mechanisms is the function of dimension parameters and input motion (or time). Considering randomness of tolerance, the motion error function is a random variable at a time point of the motion range of mechanisms. But it is a stochastic process over the all of motion range. Based on motion error model of planar four-bar function generator, the analytic equations of mean value function, standard deviation function, autocorrelation function and autocovariance function are derived. The numerical results show that the motion error, which includes structure error and random error, is a general stochastic process.