There are described herein methods and systems for operating an electric motor of a watercraft. In one method, the electric motor of the watercraft is controlled based on commands received from an accelerator of the watercraft, a sensor signal is received from at least one sensor of the watercraft while the electric motor is in operation, the sensor signal indicative of an undesirable condition of a water intake of the watercraft, and a change is effected to the controlling of the electric motor in response to receiving the sensor signal.

System, apparatus, and methods for controlling a motor by using servo-to-edge direction feedback are disclosed. An exemplary apparatus comprises: a fiber optic rotary junction (FORJ) having a rotatable portion; a motor to rotate the rotatable portion; a connector to connect the rotatable portion to a rotatable fiber of an imaging probe; a sensor positioned in close proximity to a target and configured to output a signal indicative of which one of at least two distinguishable regions of the target is proximal to the sensor; and a controller configured to control the rotational direction of the motor based on the sensor signal. In one embodiment, the motor is a servo-motor, and the rotation of the motor and/or rotatable portion is controlled by a servo-loop to change the rotation direction of the motor back-and-forth around a predetermined rotational position without the use of an encoder.

System, apparatus, and methods for controlling a motor by using servo-to-edge direction feedback are disclosed. An exemplary apparatus comprises: a fiber optic rotary junction (FORJ) having a rotatable portion; a motor to rotate the rotatable portion; a connector to connect the rotatable portion to a rotatable fiber of an imaging probe; a sensor positioned in close proximity to a target and configured to output a signal indicative of which one of at least two distinguishable regions of the target is proximal to the sensor; and a controller configured to control the rotational direction of the motor based on the sensor signal. In one embodiment, the motor is a servo-motor, and the rotation of the motor and/or rotatable portion is controlled by a servo-loop to change the rotation direction of the motor back-and-forth around a predetermined rotational position without the use of an encoder.

A motor control apparatus includes control circuitry and rotation direction adjusting circuitry. The control circuitry is configured to output, in accordance with a phase sequence with respect to a motor, a drive command signal which is generated based on a motor rotation signal output from a motor rotation detector to control the motor. The rotation direction adjusting circuitry is configured to match the phase sequence with rotation direction information included in the motor rotation signal if a first trouble signal showing excessive motor current or excessive motor speed is input via an operation unit.

Examples described herein provide a method for direction control of a motor of a gate crossing mechanism. The method includes providing, by a field-effect transistor (FET) driver, a first voltage via a high output to an open contact of a first relay and to a closed contact of a second relay. The first voltage causes a shaft of the motor to turn in a first direction. The method further includes providing, by the FET driver, a second voltage via a low output to a closed contact of the first relay and to an open contact of the second relay. The second voltage causes the shaft of the motor to turn in a second direction opposite the first direction.

Examples described herein provide a method for direction control of a motor of a gate crossing mechanism. The method includes providing, by a field-effect transistor (FET) driver, a first voltage via a high output to an open contact of a first relay and to a closed contact of a second relay. The first voltage causes a shaft of the motor to turn in a first direction. The method further includes providing, by the FET driver, a second voltage via a low output to a closed contact of the first relay and to an open contact of the second relay. The second voltage causes the shaft of the motor to turn in a second direction opposite the first direction.

A windshield wiper system includes a three-phase motor, the three-phase inverter, a brake circuit, and a controller. The controller transmits commutation signals to the three-phase inverter to drive the motor according to an inboard-to-outboard speed profile and to drive the motor according to an outboard-to-inboard speed profile. The controller activates the brake circuit based on the inboard-to outboard speed profile, or the outboard-to-inboard speed profile, and a direct current bus voltage.

A method of estimating and compensating an interference torque of a lifting system includes steps of: continuously integrating a speed of a motor and specifying an integration value to be zero if the integration value is negative when the elevator car moves upward and downward in a hoist way; estimating a rope load constant of a wire rope according to an initial position and a maximum travel position, and calculating a rope load torque according to the maximum travel position, the rope load constant and a present position of the motor; estimating a car and counterweight load torque according to a car weight of the elevator car and a counterweight weight; estimating an interference torque according to the rope load torque and the car and counterweight load torque, and performing a feedforward compensation to the motor based on the interference torque.

A method of estimating and compensating an interference torque of a lifting system includes steps of: continuously integrating a speed of a motor and specifying an integration value to be zero if the integration value is negative when the elevator car moves upward and downward in a hoist way; estimating a rope load constant of a wire rope according to an initial position and a maximum travel position, and calculating a rope load torque according to the maximum travel position, the rope load constant and a present position of the motor; estimating a car and counterweight load torque according to a car weight of the elevator car and a counterweight weight; estimating an interference torque according to the rope load torque and the car and counterweight load torque, and performing a feedforward compensation to the motor based on the interference torque.

When the rotation direction of a motor is determined by a connection determination unit not to match a rotation command, the phase sequence of a current detection signal and the phase sequence of a voltage command are changed by a phase sequence change unit, or the positive/reverse polarity of an encoding signal outputted from an encoder is inverted by the phase sequence change unit, whereby the rotation direction of the motor controlled by a motor control device can match the rotation command.