Rotary valve with brake mode

A method comprising:

• receiving at a controller a command to move a hydraulic actuator in a given direction at a given speed, wherein the hydraulic actuator includes a first chamber and a second chamber;
• and
• in response to the command, the controller providing a signal to a valve to operate the valve, wherein the valve comprises:
• a sleeve having a plurality of openings configured along a length of the sleeve, wherein the plurality of openings includes at least:
• a first opening configured to receive pressurized fluid from a supply line, a second opening configured to communicate fluid to a return line including fluid having pressure lower than that of the pressurized fluid, a third opening configured to communicate fluid to and from the first chamber of the hydraulic actuator, and a fourth opening configured to communicate fluid to and from the second chamber of the hydraulic actuator;
• a spool rotatable within the sleeve, the spool including a respective plurality of openings along a length of the spool corresponding to the plurality of openings of the sleeve;
• and
• a rotary actuator coupled to the spool for rotating the spool within the sleeve, wherein the rotary actuator operates to rotate the spool, based on the signal, to a given rotary position in a clockwise or a counter-clockwise direction to cause at least a partial alignment between a subset of the respective plurality of openings of the spool and a subset of the plurality of openings of the sleeve so as to:
• (i) connect one of the first chamber and the second chamber of the hydraulic actuator to the supply line, and connect the other chamber to the return line, or (ii) connect both the first chamber and the second chamber of the hydraulic actuator to the return line, wherein rotation of the spool to reach the given rotary position takes a first amount of time if the spool rotates in the clockwise direction and takes a second amount of time different from the first amount of time if the spool rotates in the counter-clockwise direction.

A valve system comprising:

• a sleeve having a plurality of openings configured along a length of the sleeve, wherein the plurality of openings includes at least:
• a first opening configured to communicate pressurized fluid from a supply port, a second opening configured to communicate fluid to a return port, a third opening configured to communicate fluid to and from a first chamber of a hydraulic actuator, and a fourth opening configured to communicate fluid to and from a second chamber of the hydraulic actuator;
• a spool rotatable within the sleeve, the spool including a respective plurality of openings along a length of the spool corresponding to the plurality of openings of the sleeve;
• a rotary actuator coupled to the spool for rotating the spool within the sleeve;
• and
• a controller for providing a signal to the rotary actuator to rotate the spool to a given rotary position in a clockwise or a counter-clockwise direction to cause at least a partial alignment between a subset of the respective plurality of openings of the spool and a subset of the plurality of openings of the sleeve so as to:
• (i) connect one of the first chamber and the second chamber of the hydraulic actuator to the supply port, and connect the other chamber to the return line, or (ii) connect both the first chamber and the second chamber of the hydraulic actuator to the return port, wherein rotation of the spool to reach the given rotary position takes a first amount of time if the spool rotates in the clockwise direction and takes a second amount of time different from the first amount of time if the spool rotates in the counter-clockwise direction.