Variable torque control of a stepper motor
First Claim
1. A stepper motor assembly comprising:
- a stepper motor having a first coil, a second coil, a stator and a motor shaft, the motor shaft coupled to a first part of a device and the stator coupled to a second part of the device that moves relative to the first part, the stepper motor to rotate the first part to a control position or maintain the first part in the control position with respect to the second part;
an encoder to detect rotation of the motor shaft and output position feedback in response to the detected rotation, the position feedback corresponding to an actual position of the motor shaft relative to the stator;
a driver to receive a vector control signal and to generate a vector control current to be output to the stepper motor to cause the stepper motor, when unhindered, to rotate to the control position or maintain the control position, the vector control current having a first current applied to the first coil and a second current applied to the second coil; and
a controller to receive the position feedback, to generate the vector control signal for the driver to cause the stepper motor to rotate to the control position or to maintain the control position, and to adjust a torque applied by the stepper motor by;
determining an occurrence of user intervention with the motor shaft based at least in part on the control position being different than the actual position based at least in part on the position feedback;
decreasing the torque during at least a portion of the occurrence of the user interaction;
determining an end of the occurrence of the user interaction; and
increasing the torque to at least a holding torque to maintain a new position of the first part relative to the second part, the new position resulting at least partly from the user intervention.
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0 Petitions
Accused Products
Abstract
A stepper motor may be controlled by a controller to provide extended revolution of a motor shaft while operating in a first mode and to allow a user to manually intervene with an intended position or rotation of the motor shaft while operating in a second mode. In some embodiments, the controller may adjust a torque applied to the stepper mode during operation of the stepper motor. The controller may reduce a torque applied by the stepper motor to a lower torque while the user intervenes with the intended position or rotation of the motor and increase the torque to a holding torque after the user intervention has ended. Thus, the controller may dynamically adjust a torque of the stepper motor in response to detection of the user intervention.
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Citations
20 Claims
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1. A stepper motor assembly comprising:
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a stepper motor having a first coil, a second coil, a stator and a motor shaft, the motor shaft coupled to a first part of a device and the stator coupled to a second part of the device that moves relative to the first part, the stepper motor to rotate the first part to a control position or maintain the first part in the control position with respect to the second part; an encoder to detect rotation of the motor shaft and output position feedback in response to the detected rotation, the position feedback corresponding to an actual position of the motor shaft relative to the stator; a driver to receive a vector control signal and to generate a vector control current to be output to the stepper motor to cause the stepper motor, when unhindered, to rotate to the control position or maintain the control position, the vector control current having a first current applied to the first coil and a second current applied to the second coil; and a controller to receive the position feedback, to generate the vector control signal for the driver to cause the stepper motor to rotate to the control position or to maintain the control position, and to adjust a torque applied by the stepper motor by; determining an occurrence of user intervention with the motor shaft based at least in part on the control position being different than the actual position based at least in part on the position feedback; decreasing the torque during at least a portion of the occurrence of the user interaction; determining an end of the occurrence of the user interaction; and increasing the torque to at least a holding torque to maintain a new position of the first part relative to the second part, the new position resulting at least partly from the user intervention. - View Dependent Claims (2, 3, 4)
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5. A method comprising:
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determining an occurrence of user intervention of rotation of a motor shaft of a stepper motor based on one or more of a control position of the motor shaft being different than an actual position of the motor shaft or a current feedback received by a controller indicating that the actual position is different than the control position; decreasing a torque applied by the stepper motor to the motor shaft during at least a portion of the user interaction; determining an end of the occurrence of the user interaction; and increasing the torque applied to the motor shaft to at least a holding torque to maintain a new position of the motor shaft. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A system comprising:
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a stepper motor to rotate a motor shaft to a control position or maintain the motor shaft in the control position; and a controller to receive at least one of position feedback or a signal from a proximity sensor, and to generate a control to cause the stepper motor to rotate to the control position or to maintain the control position, the controller to determine a torque to be applied by the stepper motor, the torque determined by; determining an occurrence of user intervention with the motor shaft based at least in part on the position feedback or the signal from the proximity sensor; decreasing the torque during at least a portion of the occurrence of the user interaction; determining an end of the occurrence of the user interaction; and increasing the torque to maintain a new position of the motor shaft. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification