Control system for overcoming stiction, friction in electric motors

Claim 2

An electric motor control system for overcoming the effects of stiction, friction or the like in a member movable by the motor to and from a desired position or between predetermined positions, including detecting means responsive to the arrival of the member at such a position and operatively connected to switching means effective to reverse the direction of rotation of the motor to cause the member to oscillate about such position, and damping means operative in response to such oscillations to reduce the power supplied to the motor so as to reduce the amplitude of the oscillations whereby the member is maintained continuously oscillating with limited amplitude about the desired position.

Claim 3

An electric motor control system according to claim 1, in which said damping means comprises means operative in response to repeated operation of said switching means to increase electrical resistance in circuit with the motor.

Claim 4

An electric motor control system according to claim 2 in which said damping means includes electronic switch means connected to increase the resistance of the motor circuit when actuated, and means operative only in response to repeated operation of said switching means to actuate said electronic switch means.

Claim 5

An electric motor control system according to claim 3 in which the means operative to actuate said electronic switch means comprises means operative only in response to repeated operation of said switching means to derive an alternating current therefrom, and rectifying means connected to rectify the alternating current, the electronic switch means being actuated by the rectified current.

Claim 6

An electric motor control system for overcoming the effects of stiction, friction or the like in a member movable by the motor to and from a desired position or between predetermined positions, including detecting means responsive to the arrival of the member at such position and operatively connected to electronic switching means effective to reverse the direction of rotation of the motor to cause the member to oscillate about such position, capacitive means connected to pass such oscillations to rectifying means and electronic switch means connected for actuation by the rectified signals and operative to increase electrical resistance in circuit with the motor whereby to reduce the power supplied to the motor such that the member is maintained continuously oscillating with limited amplitude about the desired position.

Claim 7

An electric motor control system for overcoming the effects of stiction, friction or the like in a member movable by the motor to and from a desired position or between predetermined positions, including detecting means responsive to the arrival of the member at such position and operatively connected to electronic switching means effective to reverse the direction of rotation of the motor to cause the member to oscillate about such position, capacitive means connected to pass such oscillations to rectifying means and electronic switch means connected for actuation by the rectified signals and operative to increase electrical resistance in circuit with the motor whereby to reduce the power supplied to the motor such that the member is maintained continuously oscillating with limited amplitude about the desired position.

Claim 10

A method according to claim 6 wherein said oscillations are used to energize electronic switch means effective to increase electrical resistance in circuit with the motor whereby to reduce the power supplied to the motor.

Claim 11

A method according to claim 7 wherein said oscillations are fed through capacitive means to rectifying means, said electronic switch means being actuated by the rectified current.

Claim 12

In a servomechanism having a movable member subject to frictional forces which may introduce positional error in desired positions thereof, drive means for moving said member, and a power source connected to and energizing said drive means, in combination: control means responsive to positioning of said member on opposite sides of a desired position for reversing the connection between said power source and said drive means so as continuously to maintain said member in oscillatory motion about said desired position; and damping means responsive to the amplitude of said oscillatory motion about said desired position for reducing the power supplied to said drive means thereby to limit such amplitude to a predetermined value.

Claim 13

In a servomechanism having a movable member subject to frictional forces which may introduce positional error in desired positions thereof, drive means for moving said member, and a power source connected to and energizing said drive means, in combination: control means responsive to positioning of said member on opposite sides of a desired position for reversing the connection between said power source and said drive means so as continuously to maintain said member in oscillatory motion about said desired position; and damping means responsive to the amplitude of said oscillatory motion about said desired position for reducing the power supplied to said drive means thereby to limit such amplitude to a predetermined value.

Claim 14

In a servomechanism as defined in claim 9 wherein said control means includes switch means having two states respectively for the positions of said member on opposite sides of said desired position, and a current reversing circuit controlled by the states of said switch means.

Claim 15

In a servomechanism as defined in claim 10 wherein said damping means includes a capacitor charged according to the time durations of said states of the switch means, and second switch means controlled by said capacitor for reducing the power supplied to said drive means when said capacitor charges to a predetermined value.

Claim 16

In a servomechanism as defined in claim 9 wherein said damping means includes capacitor means charged according to the amplitudes of said member on the opposite sides of said desired position, and switch means controlled by said capacitor means for reducing the power supplied to said drive means when said capacitor means is charged to a predetermined value.