Power driver for regulating a servomotor

Claim 2

A power driver for supplying electrical current to a DC servomotor in response to an error signal, including: means for monitoring current in the motor and producing a feedback signal proportional to the amplitude and direction of motor drive current including a bridge circuit having an impedance including the motor coil and means for maintaining approximately a constant voltage level across the impedance during the time period drive current is not supplied to the motor, and second means for comparing the error signal and the feedback signal, the second means producing a drive signal to pulse the motor when an imbalance occurs between the error signal and the feedback signal.

Claim 3

A power driver as defined in claim 1 wherein: the second means produces a drive signal having a series of pulses of either polarity occurring at a regular frequency, the level of the signal returning to zero between successive pulses.

Claim 4

A power driver as defined in claim 2, wherein: the second means includes a ramp generator producing a ramp signal which is combined with the error signal and the feedback signal to produce the motor drive signal, and the pulses of the drive signal vary in width in direct proportion to the magnitude of the difference between the error signal and the feedback signal.

Claim 5

A power driver for supplying electrical current to a DC servomotor in response to an error signal, including: means for monitoring current in the motor and producing a feedback signal proportional to the amplitude and direction of motor drive current, and including a bridge circuit which includes a resistor and the movable coil of the motor connected in series, switch means for selectively pulsing the motor in either direction, and means for maintaining approximately a constant voltage level across the coil and resistor during the time period between pulses and power, and second means for comparing the error signal and the feedback signal, the second means producing a drive signal to pulse the motor when an imbalance occurs between the error signal and the feedback signal.

Claim 6

A power driver for supplying electrical current to a DC servomotor in response to an error signal, including: means for monitoring current in the motor and producing a feedback signal proportional to the amplitude and direction of motor drive current, and including a bridge circuit which includes a resistor and the movable coil of the motor connected in series, switch means for selectively pulsing the motor in either direction, and means for maintaining approximately a constant voltage level across the coil and resistor during the time period between pulses and power, and second means for comparing the error signal and the feedback signal, the second means producing a drive signal to pulse the motor when an imbalance occurs between the error signal and the feedback signal.

Claim 7

A power driver as defined in claim 2 wherein: the switch means includes a single switch connected to one side of the bridge for controlling the direction of current flow and a pair of switches connected to the other side of the bridge for controlling the duration of current flow.

Claim 8

A power driver for supplying electrical current to a DC servomotor in response to an error signal, including: means for monitoring current in the motor and producing a feedback signal proportional to the motor drive current, second means for comparing the error signal and the feedback signal, the second means producing a drive signal to pulse the motor when an imbalance occurs between the error signal and the feedback signal, the second means including amplifying means for producing a differential output indicating direction and magnitude of position error, and comparator means connected between the amplifying means and the motor, the comparator means receiving as inputs the output from the amplifying means and current feedback signals from the first means.

Claim 9

A power driver for supplying electrical current to a DC servomotor in response to an error signal, including: means for monitoring current in the motor and producing a feedback signal proportional to the motor drive current, second means for comparing the error signal and the feedback signal, the second means producing a drive signal to pulse the motor when an imbalance occurs between the error signal and the feedback signal, the second means including amplifying means for producing a differential output indicating direction and magnitude of position error, and comparator means connected between the amplifying means and the motor, the comparator means receiving as inputs the output from the amplifying means and current feedback signals from the first means.

Claim 10

A power driver as Defined in claim 6, wherein; the amplifying means produces a first signal-indicating magnitude of position error in one direction and a second signal-indicating magnitude of position error in the opposite direction, the first means produces a first feedback signal proportional to motor current in one direction and a second feedback signal proportional to motor current in the opposite direction, and the comparator means includes one comparator connected to receive the first signal from the amplifying means and the first feedback signal and another comparator connected to receive the second signal from the amplifying means and the second feedback signal.

Claim 11

A power driver as defined in claim 6 which includes: means for periodically interrupting the current feedback signal to the comparator means at a frequency of at least 20 times the highest frequency of interest in the control system.

Claim 12

A power driver as defined in claim 8 wherein: the last named means produces an interruption signal which is slightly longer than the internal delays of the power driver circuit components and approximately 10 percent of the period between interruption signals.

Claim 13

A power driver for supplying electrical energy to a servomotor in response to an error signal include: circuit means for supplying electrical energy to the motor including input and output switches for interrupting the electrical circuit between the energy supply and motor, first means for monitoring the electrical energy supplied to the motor and for producing a feedback signal proportional to the motor energy supplied, second means for comparing the error signal and the feedback signal for producing a drive signal, and means to actuate the motor input switch only in response to the drive signal while leaving the output switch closed thereby to regulate the speed of the servomotor while limiting the voltage buildup in the circuit means due to the inductive effect of the motor.

Claim 14

A power driver for supplying electrical energy to a servomotor in response to an error signal include: circuit means for supplying electrical energy to the motor including input and output switches for interrupting the electrical circuit between the energy supply and motor, first means for monitoring the electrical energy supplied to the motor and for producing a feedback signal proportional to the motor energy supplied, second means for comparing the error signal and the feedback signal for producing a drive signal, and means to actuate the motor input switch only in response to the drive signal while leaving the output switch closed thereby to regulate the speed of the servomotor while limiting the voltage buildup in the circuit means due to the inductive effect of the motor.