Force controlled hydraulic cylinder towards a modular servo unit

Closed loop control of hydraulic drives are today used mostly in high performance, high accuracy industrial applications with expensive components. The technology of performing closed loop control with less expensive off-the shelf components have been available for some time. Though there are not a lot of such drives on the market today. One problem is the relative difficulty to tune the control parameters of a hydraulic drive. This paper suggests a new control strategy, based on force control, which is versatile and also simplifies the on site implementation. A force servo based on optimal control is introduced and an example of a position controller based on the force servo is elaborated