The control system for a traction drive must produce robust response with respect to a change in the mass of the workpiece on the slide. It has been found that a conventional controller cannot tolerate a large range of mass change. In this paper, a discrete-time H, controller is described that has achieved robustness with respect to a change in mass. Comparison between the robustness of two controllers, PID and H, , is given by the experimental results and shows the improvement using the H, controller.