Methods and apparatus for reducing following errors in the servo drives of positioning and velocity control systems wherein the commanded position is signaled and updated by increments Delta X during each successive equal time periods Delta T, -so as to cause the controlled member movable along any axis X to travel at a velocity Vx Delta X/ Delta T. The commanded position is updated by iterative computations at least once during each period Delta T, and the Delta X increments to be used for such updating are numerically signaled and can be changed as frequently as once during each period Delta T. In order to create a feed forward signal for application to the servo in a sense additive to the position command signal, the digitally signaled number Delta X is converted into a corresponding analog signal. In the preferred arrangement, this conversion is accomplished by a counter which is preset to the number Delta X at regularly recurring instants and arranged to count down whenever the number held in the counter is other than zero. A decoder responsive to a predetermined count, for example zero, not only terminates the counting action until the next presetting but also produces a constant frequency, variable duty cycle squarewave having an average or dc. value proportional to the number Delta X and which serves as an accurate feed forward input to the servo.