Method and apparatus for compensating for windup in a machine
AssigneeVickers, Incorporated
InventorStephen J. Yutkowitz
Life of this patent
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Abstract
A method and apparatus for compensating for the effects of compliant elements in a positioning system is provided. The amount of compensation to be applied can be determined by measuring the lost motion errors which are prevalent during continuous motion of the movable member of the system. The compensation value determined can be used to adjust servo control commands, such as position commands for example. Preferably, the compensation is applied when the movable member is in motion and removed when the movable member comes to a stop. Even more preferably, the compensation is applied and removed gradually. The compensation can be used in additional to friction compensation and backlash compensation, and can be implemented in a machine tool system.
Claims27
A method of compensating for lost motion in a machine having a movable member controlled by an actuator, comprising:
- producing a position command which is representative of the desired position of the movable member;
- moving the movable member in response to the position command;
- determining a windup error value associated with the machine by measuring a variation between the desired position and the actual position of the movable member that occurs when the movable member is in motion;
- providing actuator commands for control of the actuator movement;
- and
- when the movable member is in motion, adding a windup compensation amount to the actuator commands to adjust the control of the actuator movement, wherein the windup compensation amount is based upon the windup error value determined.
A method of compensating for lost motion in a machine having a movable member controlled by an actuator, comprising:
- compensating for persistent lost motion errors associated with the machine;
- determining a non-persistent lost motion error associated with the machine by measuring lost motion remaining after the step of compensating for persistent lost motion;
- when the movable member is in motion, applying a windup compensation value to an actuator control command, wherein the windup compensation value is based upon the non-persistent lost motion error;
- and
- subsequently removing the windup compensation value from the actuator control command when the movable member is stopped.
An apparatus for compensating for lost motion errors in a machine having a movable member controlled by an actuator, comprising:
- a position command generator situated in communication with the actuator to apply position commands to the actuator;
- an movable member motion detector;
- and
- a windup compensator arranged in communication with the position command generator and the motion detector, wherein the windup compensator is adapted to adjust the position commands based upon a predetermined windup value when the movable member is in motion, wherein the predetermined windup value is based upon positioning error measured while the member was in motion.
A method for compensating for lost motion in a machine having a movable member controlled by a motor, comprising:
- moving the motor according to a plurality of desired positions, the movement of the motor resulting in movement of the movable member;
- for each desired position, waiting until the movable member has come to a stop, and determining the difference between each desired position and the actual position of the movable member;
- establishing error compensation values based upon the differences determined;
- moving the movable member in a continuous motion along a predetermined desired path by applying a series of commands to the motor, wherein the series of commands is compensated based upon the error compensation values;
- measuring in-motion variation between the predetermined desired path and the actual path of the member, wherein the in-motion variation occurs when the movable member is in motion;
- establishing a windup compensation value based upon the in-motion variation;
- and
- adjusting position commands applied to the motor based upon the windup compensation value.
Dependencies are inferred from the claim text.