Contouring accuracy with 2-axis continuous and discretedata servos

This paper describes results obtained for the errors involved in describing various trajectories with a 2-axis position-control system of the type having appreciable velocity lag. A digital simulation was used to compute the results. It is shown that the machining accuracy depends largely on the servos having identical parameters and that even a small amount of mismatch may cause appreciable errors. Discrete-data servos are also considered, and it is shown that, for accurate machining of circular trajectories, there is an optimum value of the damping factor, which depends on the sampling period. The results given assist in the selection of a suitable sampling period.