Determining null bias of a hydraulic valve of a robot
First Claim
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1. A method comprising:
- identifying, by a controller of a robot, an operating state at which (i) a velocity of a hydraulic actuator configured to operate a movable member of the robot is less than a threshold velocity, (ii) a force applied, or experienced, by the hydraulic actuator is less than a threshold force, and (iii) a pressure level of hydraulic fluid at a source of pressurized fluid is above a threshold pressure level;
determining a valve command that corresponds to the operating state, wherein the valve command is provided to a valve configured to control flow to and from the hydraulic actuator, wherein the valve includes a spool movable within a body of the valve, and wherein the valve command causes the spool to move within the body of the valve to a position that induces the operating state; and
determining a null bias signal based on the valve command, wherein the null bias signal, when provided to the valve, places the spool at a null position at which the spool substantially blocks fluid flow through the body.
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Abstract
An example method includes identifying an operating state at which a velocity of a hydraulic actuator configured to operate a movable member of a robot is less than a threshold velocity and an actuator force is less than a threshold force, determining a valve command that corresponds to the operating state, such that the valve command is provided to a valve configured to control flow to and from the hydraulic actuator, and the valve includes a spool movable within a body of the valve, and the valve command causes the spool to move within the body of the valve to a position that induces the operating state, and determining a null bias signal based on the valve command.
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Citations
20 Claims
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1. A method comprising:
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identifying, by a controller of a robot, an operating state at which (i) a velocity of a hydraulic actuator configured to operate a movable member of the robot is less than a threshold velocity, (ii) a force applied, or experienced, by the hydraulic actuator is less than a threshold force, and (iii) a pressure level of hydraulic fluid at a source of pressurized fluid is above a threshold pressure level; determining a valve command that corresponds to the operating state, wherein the valve command is provided to a valve configured to control flow to and from the hydraulic actuator, wherein the valve includes a spool movable within a body of the valve, and wherein the valve command causes the spool to move within the body of the valve to a position that induces the operating state; and determining a null bias signal based on the valve command, wherein the null bias signal, when provided to the valve, places the spool at a null position at which the spool substantially blocks fluid flow through the body. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A robot comprising:
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at least one movable member; a hydraulic system comprising at least (i) a hydraulic actuator configured to operate the movable member, (ii) a valve configured to control flow to and from the hydraulic actuator, and (iii) a source of pressurized hydraulic fluid; and a controller configured to perform operations comprising; identifying a plurality of operating states, wherein at each operating state of the plurality of operating states (i) a velocity of the hydraulic actuator is less than a threshold velocity, (ii) a force applied, or experienced, by the hydraulic actuator is less than a threshold force, and (iii) a pressure level of hydraulic fluid at the source of pressurized hydraulic fluid is above a threshold pressure level; determining a plurality of valve commands that respectively correspond to the plurality operating states, wherein the valve includes a spool movable within a body of the valve, and wherein each valve command of the plurality of the valve commands causes the spool to move within the body of the valve to a position that induces a respective operating state of the plurality of operating states; and determining a null bias signal based on the plurality of valve commands, wherein the null bias signal, when provided to the valve, places the spool at a null position at which the spool substantially blocks fluid flow through the body of the valve. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A method comprising:
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providing a signal to a valve to cause a spool to move within a body of the valve to allow a work port disposed on the body of the valve to be in fluid communication with a source of pressurized fluid configured to supply hydraulic fluid at a first pressure level such that a pressure level at the work port is substantially equal to the first pressure level; gradually changing the signal to the valve so as to cause the spool to gradually move in a first direction within the body of the valve until the pressure level at the work port reaches a second pressure level that is lower than the first pressure level, wherein the pressure level at the work port reaches the second pressure level at a first value of the signal; maintaining the signal at the first value for a particular period of time so as to allow the pressure level at the work port to decrease below the second pressure level; gradually changing the signal to the valve so as to cause the spool to gradually move in a second direction opposite the first direction until the pressure level at the work port again reaches the second pressure level, wherein the pressure level at the work port reaches the second pressure level again at a second value of the signal; and determining a null bias signal based on the first value and the second value, wherein the null bias signal, when provided to the valve, places the spool at a null position at which the spool substantially blocks fluid flow through the body of the valve. - View Dependent Claims (19, 20)
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Specification