Aircraft landing gear steering systems and methods with enhanced shimmy protection

An aircraft comprising:

• a landing gear having (i) a chassis, (ii) at least one axle rotatably coupled to the chassis at a joint, and (iii) respective wheels mounted to respective ends of the at least one axle, such that rotation of the at least one axle about the joint causes the aircraft to be steered;
• a hydraulic actuator comprising:
• (i) a cylinder, (ii) a partition disposed in the cylinder and configured to divide the cylinder into a first partition and a second partition, (iii) a first piston slidably accommodated in the first partition and having a piston head and a rod extending from the piston head along a longitudinal axis of the cylinder, wherein the rod is coupled to the chassis, and wherein the piston head divides the first partition into a first chamber and a second chamber, and (iv) a second piston slidably accommodated in the second partition and having a respective piston head and a respective rod extending from the respective piston head along the longitudinal axis of the cylinder, wherein the respective rod is coupled to the at least one axle, and wherein the respective piston head divides the second partition into a third chamber and a fourth chamber;
• and
• a directional control valve comprising:
• (i) a first inlet port configured to be fluidly coupled to a source of pressurized fluid, (ii) a second inlet port configured to be fluidly coupled to the source of pressurized fluid, (iii) a first tank port configured to be fluidly coupled to a tank, (iv) a second tank port configured to be fluidly coupled to the tank, (v) a first workport configured to be fluidly coupled to the first chamber, (vi) a second workport configured to be fluidly coupled to the second chamber, (vii) a third workport configured to be fluidly coupled to the third chamber, and (viii) a fourth workport configured to be fluidly coupled to the fourth chamber.

A method of steering an aircraft, the method comprising:

• receiving, at a controller, a request to steer the aircraft in a particular direction, wherein the aircraft comprises:
• (i) a landing gear having a chassis, at least one axle rotatably coupled to the chassis at a joint, and respective wheels mounted to respective ends of the at least one axle, such that rotation of the at least one axle about the joint causes the aircraft to be steered, (ii) a hydraulic actuator comprising a cylinder, a first piston slidably accommodated in the cylinder and coupled to the chassis, and a second piston slidably accommodated in the cylinder and coupled to the at least one axle, and (iii) a directional control valve configured to control fluid flow from a source of pressurized fluid to the hydraulic actuator and fluid flow from the hydraulic actuator to a tank so as to control motion of the first piston and the second piston within the cylinder;
• and
• in response to receiving the request, sending, by the controller, a signal to actuate either a first pilot valve or a second pilot valve to provide pressurized fluid to a first pilot port of the directional control valve or to a second pilot port of the directional control valve so as to actuate the directional control valve and provide pressurized fluid to the hydraulic actuator, thereby moving at least one of the first piston and the second piston to rotate the at least one axle about the joint and steer the aircraft in the particular direction.