A hydrostatic actuator system includes an electric motor for delivering a hydraulic fluid via a piston unit. The actuator system is operating using a method in which a change in volume caused by a temperature change is sensed by a pressure measurement. The method reliably identifies a state of the transfer of the hydraulic fluid from a planetary roller transmission compartment into the master piston. The pressure measurement is continuously evaluated, and, in the event of a negative signal of the pressure measurement, suction of the hydraulic fluid by a planetary roller transmission lying in the hydraulic fluid between the electric motor and the piston unit into the piston unit is recognized and a fault signal is output.

A stage assembly (10) includes a stage (14), and a fluid actuator assembly (24) that moves the stage (14). The fluid actuator assembly (24) includes a piston housing (32) that defines a piston chamber (34); (ii) a piston (36) that separates the piston chamber (34) into a first chamber (34A) and a second chamber (34B); (iii) a supply valve (38C) that controls the flow of the working fluid (40) into the first chamber (34A); and (iv) an exhaust valve (38D) that controls the flow of the working fluid (40) out of the first chamber (34A). The supply valve (38C) has a supply orifice (250G) having a supply orifice area, and the exhaust valve (38D) has an exhaust orifice (352G) having an exhaust orifice area. Moreover, the supply orifice area is different from the exhaust orifice area. Further multiple valves of different sizes can be used in combination for the supply and exhaust for each chamber (34A), (34B).

A stage assembly (10) includes a stage (14), and a fluid actuator assembly (24) that moves the stage (14). The fluid actuator assembly (24) includes a piston housing (32) that defines a piston chamber (34); (ii) a piston (36) that separates the piston chamber (34) into a first chamber (34A) and a second chamber (34B); (iii) a supply valve (38C) that controls the flow of the working fluid (40) into the first chamber (34A); and (iv) an exhaust valve (38D) that controls the flow of the working fluid (40) out of the first chamber (34A). The supply valve (38C) has a supply orifice (250G) having a supply orifice area, and the exhaust valve (38D) has an exhaust orifice (352G) having an exhaust orifice area. Moreover, the supply orifice area is different from the exhaust orifice area. Further multiple valves of different sizes can be used in combination for the supply and exhaust for each chamber (34A), (34B).

The subject matter of this specification can be embodied in, among other things, a controller apparatus that includes a digital controller configured to provide a digital position signal based on a setpoint and a differential analog feedback signal, and a converter circuit configured to provide a differential analog electrohydraulic servo valve position control signal based on the digital position signal, and provide the differential analog feedback signal based on the differential analog electrohydraulic servo valve position control signal.

Systems and methods for providing vehicle condition indicators are provided. The method for controlling the vehicle includes receiving sensor information from a plurality of sensors associated with the vehicle. The sensor information includes throttle values and lateral acceleration values. The method also includes analyzing the throttle values for a plurality of points in time to determine whether to activate an aggressive throttle flag. The method further includes analyzing the lateral acceleration values for the plurality of points in time to determine whether to activate an aggressive lateral acceleration flag. In addition, the method includes activating a fluid consumption detection enable flag when the aggressive throttle flag and the aggressive lateral acceleration flag are both active.

Systems and methods for providing vehicle condition indicators are provided. The method for controlling the vehicle includes receiving sensor information from a plurality of sensors associated with the vehicle. The sensor information includes throttle values and lateral acceleration values. The method also includes analyzing the throttle values for a plurality of points in time to determine whether to activate an aggressive throttle flag. The method further includes analyzing the lateral acceleration values for the plurality of points in time to determine whether to activate an aggressive lateral acceleration flag. In addition, the method includes activating a fluid consumption detection enable flag when the aggressive throttle flag and the aggressive lateral acceleration flag are both active.

The subject matter of this specification can be embodied in, among other things, an electrohydraulic positioning control system that includes a shuttle valve configured to direct fluid flow between a selectable one of a first fluid port and a second fluid port, and a fluid outlet configured to be fluidically connected to a fluid actuator, a first servo valve controllable to selectably permit and block flow between the first fluid port, a fluid source, and a fluid drain, a second servo valve controllable to selectably permit and block flow between the second fluid port, the fluid source, and the fluid drain, a first servo controller configured to provide a first health signal and control the first servo valve based on a second health signal, and a second servo controller configured to provide the second health signal and control the second servo valve based on the first health signal.

The subject matter of this specification can be embodied in, among other things, an electrohydraulic positioning control system that includes a shuttle valve configured to direct fluid flow between a selectable one of a first fluid port and a second fluid port, and a fluid outlet configured to be fluidically connected to a fluid actuator, a first servo valve controllable to selectably permit and block flow between the first fluid port, a fluid source, and a fluid drain, a second servo valve controllable to selectably permit and block flow between the second fluid port, the fluid source, and the fluid drain, a first servo controller configured to provide a first health signal and control the first servo valve based on a second health signal, and a second servo controller configured to provide the second health signal and control the second servo valve based on the first health signal.

The subject matter of this specification can be embodied in, among other things, a method that includes actuating a closure member at a predetermined first velocity a predetermined first number of cycles between a first configuration and a second configuration, actuating the closure member at a predetermined second velocity a predetermined second number of cycles between the first and the second configuration, actuating the closure member at a predetermined third velocity a predetermined third number of cycles and the second configuration, actuating the closure member at a predetermined fourth velocity a predetermined fourth number of cycles and the second configuration, and actuating the closure member to the second configuration at a predetermined fifth velocity for a predetermined flushing period.

A servo valve unit capable of precisely controlling the position of a pneumatic cylinder that does not require a servo amplifier and a small sized and/or high durability servo valve unit are disclosed. The servo valve unit comprises a unit body having a first end portion and a second end portion, a first valve portion, a second valve portion, a first seal member that opens and closes the first valve portion, a second seal member that opens and closes the second valve portion, a first drive mechanism that drives the first seal member by a first electric pulse, a second seal member that drives the second seal member by a second electric pulse, a supply flow path that extends between the first end and the first valve, an exhaust flow path that extends between the second end and the second valve, a common flow path connected to the supply flow path and the exhaust flow path via the first valve portion and the second valve portion, and a drive flow path connected to the pneumatic actuator. The first drive mechanism and the second drive mechanism are arranged in a drive mechanism arrangement portion located between the first end portion and the second end portion. The drive air flow path can branch from a branch portion located between the drive mechanism arrangement portion and the first end portion and extends to the first end portion. Alternatively drive air flow path can branch from the common flow path from a branch portion located between the drive mechanism arrangement portion and the second end portion and extends to the second end portion.