Abstract: A fluid control system may comprise a pump, a tank, and an actuator including a working chamber. The system may be operative to control rotational movement of a swing structure and movement of an least one implement. A valve assembly may be configured to control fluid communication between the working chamber and the tank and to control fluid communication between the working chamber and the pump. An input device may be operative to selectively control movement of the swing structure. The system may include a controller in communication with the valve assembly and the input device. The controller may be configured to control a flow condition of the working chamber through a sensed pressure condition of the working chamber and a command from the input device.

Abstract: A method for controlling a hydraulic system may include receiving an input command from an input device, generating a desired working pressure value relating to a working chamber of an actuator based on the input command, and generating a desired pressure value relating to a non-working chamber of the actuator based on the input command. The method may also include operating a valve assembly to control a fluid flow condition of the working chamber and to control fluid flow from the non-working chamber.

Abstract: A method for controlling a hydraulic system may include receiving an input command from an input device, generating a desired working pressure value relating to a working chamber of an actuator based on the input command, and generating a desired pressure value relating to a non-working chamber of the actuator based on the input command. The method may also include operating a valve assembly to control a fluid flow condition of the working chamber and to control fluid flow from the non-working chamber.

Abstract: A fluid control system may comprise a pump, a tank, and an actuator including a working chamber. The system may be operative to control rotational movement of a swing structure and movement of an least one implement. A valve assembly may be configured to control fluid communication between the working chamber and the tank and to control fluid communication between the working chamber and the pump. An input device may be operative to selectively control movement of the swing structure. The system may include a controller in communication with the valve assembly and the input device. The controller may be configured to control a flow condition of the working chamber through a sensed pressure condition of the working chamber and a command from the input device.

Abstract: A system and method for controllably positioning a hydraulic actuator which is operably connected to a control surface includes at least one main control valve for controlling the hydraulic pressure supplied to the actuator in response to a control signal indicative of a predetermined actuator position and at least one parallel control valve for supplying additional hydraulic pressure to the actuator in response to an error signal indicative of the difference between the position of the actuator and the predetermined actuator position to thereby correct for any differences indicated by the error signal. By correcting for any differences indicated by the error signal, the errors in positioning the control surface can be decreased and the stiffness of the control surface can be increased.