Patent ID: 7021191

Claim:
A position control system for a fluid operated cylinder having at least one fluid chamber defined by a piston located within a housing for movement between first and second end limits of travel, the system comprising; at least two electrically actuated proportional flow valves connected to each port of the fluid operated cylinder to be controlled for selectively and proportionally controlling fluid flow into and out of the at least one fluid chamber of the fluid operated cylinder to be controlled; at least one pressure sensor for measuring fluid pressure with respect to each chamber of the fluid operated cylinder to be controlled; at least one discrete position sensor including a first position sensor located adjacent a midpoint of the fluid operated cylinder to be controlled for sensing a discrete centered position of the piston within the cylinder; and a controller having a control program operably connected to the at least two valves, the at least one pressure sensor, and the at least one position sensor for controlling actuation of the at least two valves in response to pressure measured by the at least one pressure sensor and location measured by the at least one position sensor, the controller having the control program for calculating a required pressure in the at least one expandable fluid chamber for moving the piston a desired distance within the housing from the discrete centered position located midway with respect to the housing, and for controlling the at least two electrically actuated proportional flow valves to obtain the calculated pressure within the at least one expandable fluid chamber corresponding to the desired distance of movement for the piston within the housing.