Curvature control

Claim 2

Apparatus of the class described for positioning an element along a path said apparatus including in combination: a voltage source; a tangent potentiometer being coupled across said voltage source, said tangent potentiometer including a resistive element and a movable wiper arm which provides a changeable voltage depending upon the position of the wiper arm on the resistive element; a first linear potentiometer being coupled to the wiper arm of said tangent potentiometer and having a voltage potential thereacross as set by the wiper arm of said tangent potentiometer, said first potentiometer including a resistive element and a wiper arm which provides a changeable voltage on said first linear potentiometer dependent upon the position of the wiper arm on the resistive element thereof; a second linear potentiometer including a resistive element being coupled across said voltage source, and a moveable wiper arm; a difference amplifier having a first input means coupled to the wiper arm of said first linear potentiometer and a second input means coupled to the wiper arm of said second linear potentiometer, for providing an output signal when the voltage applied to the first and second inputs are of different levels; a source of index signals for providing electrical signals at predetermined index times; first feedback means coupled between said source of index signals and the wiper arm of said first linear potentiometer and responsive to the electrical signals from said source for advancing the position of the wiper arm of said first linear potentiometer and moving the indexed element in a first direction during the predetermined index times; second feedback means coupled to the wiper arm of said second linear potentiometer for advancing the position of the wiper arm of said second linear potentiometer and moving the indexed element in a second direction orthogonal to said first direction, when electrical signals from said source are applied thereto; and gating means coupled between said source and said second feedback means and being responsive to the output signal from said difference amplifier for gating signals from said source to said second feedback means.

Claim 3

The combination as defined in claim 1 wherein said source of indexing signals including: a switching means being enabled at predetermined index times; a timer circuit being coupled to said switching means and being enabled thereby; a pulse oscillator being coupled to said timer circuit and being a enabled thereby during the occurrence of said timing signals; and a pulse translator being coupled to said oscillator for providing uniform pulses to said third and fourth feedback means.

Claim 4

The combination as defined in claim 1 wherein said feedback means including stepper motors.

Claim 5

Indexing apparatus for indexing a search unit including: index control means for providing index signals during predetermined index times of said search unit; sine/cosine means including a sine output means for providing a changeable sine voltage and a cosine means for providing a changeable cosine voltage; indexing means, being coupled to said index means and said sine/cosine means and being responsive to said index means, for proportionally changing the sine and cosine voltages; a first linearly variable means having a changeable output means for varying the output voltage thereof; a first balance means, including a first input means being coupled to the sine output means of said sine/cosine means and a second input means being coupled to the changeable output means of said first linear means, for providing an output signal when the input signals are at different characteristics; a second linearly variable means having a changeable output means for varying the output thereof; a second balance means, including a first input means being coupled to the cosine output means of said sine/cosine means and a second input means being coupled to the changeable output means of said second linear means, for providing an output signal when the input signals are at different characteristics; first feedback means, being coupled to the changeable output means of said first linear means, for changing the voltage thereon; second feedback means, being coupled to the changeable output means of said second linear means, for changing the voltage thereon; a source of electrical pulses; a first gate means, being coupled between said source and said first feedback means and being responsive to the output of said first balance means, for gating electrical pulses to said first feedback means during the predetermined index time; a second gate means, being coupled between said source and said second feedback means and being responsive to the output of said first balance means, for gating electrical pulses to said first feedback means during the predetermined index time; and means responsive to the outputs of said first and second gate means for moving said search unit.

Claim 6

Indexing apparatus for indexing a search unit including: index control means for providing index signals during predetermined index times of said search unit; sine/cosine means including a sine output means for providing a changeable sine voltage and a cosine means for providing a changeable cosine voltage; indexing means, being coupled to said index means and said sine/cosine means and being responsive to said index means, for proportionally changing the sine and cosine voltages; a first linearly variable means having a changeable output means for varying the output voltage thereof; a first balance means, including a first input means being coupled to the sine output means of said sine/cosine means and a second input means being coupled to the changeable output means of said first linear means, for providing an output signal when the input signals are at different characteristics; a second linearly variable means having a changeable output means for varying the output thereof; a second balance means, including a first input means being coupled to the cosine output means of said sine/cosine means and a second input means being coupled to the changeable output means of said second linear means, for providing an output signal when the input signals are at different characteristics; first feedback means, being coupled to the changeable output means of said first linear means, for changing the voltage thereon; second feedback means, being coupled to the changeable output means of said second linear means, for changing the voltage thereon; a source of electrical pulses; a first gate means, being coupled between said source and said first feedback means and being responsive to the output of said first balance means, for gating electrical pulses to said first feedback means during the predetermined index time; a second gate means, being coupled between said source and said second feedback means and being responsive to the output of said first balance means, for gating electrical pulses to said first feedback means during the predetermined index time; and means responsive to the outputs of said first and second gate means for moving said search unit.

Claim 7

The indexing apparatus as defined in claim 4 wherein said first and second feedback means including electrical stepper motors.

Claim 8

The indexing apparatus as defined in claim 4 wherein said first and second balance means being difference amplifiers.

Claim 9

The indexing apparatus as defined in claim 4 wherein said first and second linearly variable means being linear potentiometers.

Claim 10

The indexing apparatus as defined in claim 4 wherein said sine/cosine means being a sine/cosine potentiometer.

Claim 11

The indexing apparatus as defined in claim 4 wherein said indexing means being a stepping motor.

Claim 12

The indexing apparatus as defined in claim 4 wherein said index control means including: a switching means being enabled at predetermined index times; a timer circuit being coupled to said switching means and being enAbled thereby; a pulse oscillator being coupled to said timer circuit and being enabled thereby during the occurrence of said timing signals; and a pulse translator being coupled to said oscillator for providing uniform pulses to said indexing means.

Claim 13

The indexing apparatus as defined in claim 10 wherein said first and second feedback means being electrical stepping motors.

Claim 14

Indexing apparatus for indexing a search unit of a nondestructive tester on curved workpieces said apparatus including in combination: a voltage source; an index control means for providing index signals during predetermined index times; a sine/cosine potentiometer including a sine resistive element being coupled across said voltage source and a moveable wiper arm thereon which provides a changeable sine voltage and a cosine resistive element being coupled across said voltage source and a moveable wiper arm thereon which provides a changeable cosine voltage; index motor means being coupled to the wiper arms of said sine/cosine potentiometer and said index control means and being responsive to said index control means for proportionally changing the sine and cosine voltages on the wiper arms of said sine/cosine potentiometer; a first linear potentiometer including a resistive element being coupled across said voltage source and including a moveable wiper arm for providing a changeable voltage thereon; a first difference amplifier including a first input being coupled to the wiper arm of the sine resistive element of said sine/cosine potentiometer and a second input being coupled to the wiper arm of said first linear potentiometer, for providing an output signal when the input voltages thereto are at a different voltage level; a second linear potentiometer including a resistive element being coupled across said voltage source and including a moveable wiper arm for providing a changeable voltage thereon; a second difference amplifier including a first input being coupled to the wiper arm of the cosine resistive element of said sine/cosine potentiometer and a second input being coupled to the wiper arm of said second linear potentiometer, for providing an output signal when the input voltages thereto are at different voltage levels; first feedback means, being coupled to the wiper arm of the first linear potentiometer, for advancing the position of the wiper arm in response to electrical pulses thereto; second feedback means, being coupled to the wiper arm of the second linear potentiometer, for advancing the position of the wiper arm in response to electrical pulses thereto; an oscillator for providing electrical pulses; a first gate means, being coupled between said oscillator and said first feedback means and being responsive to signals from said first difference amplifier, for gating electrical pulses from said oscillator to said first feedback means during the time said difference amplifier has an output signal therefrom; a second gate means, being coupled between said oscillator and said second feedback means and being responsive to signals from said second difference amplifier, for gating electrical pulses from said oscillator to said second feedback means during the time said second difference amplifier has an output signal therefrom; output means responsive to the outputs of said first and second gate means for moving the search unit in response to pulses thereto.

Claim 15

Indexing apparatus for indexing a search unit of a nondestructive tester on curved workpieces said apparatus including in combination: a voltage source; an index control means for providing index signals during predetermined index times; a sine/cosine potentiometer including a sine resistive element being coupled across said voltage source and a moveable wiper arm thereon which provides a changeable sine voltage and a cosine resistive element being coupled across said voltage source and a moveable wiper arm thereon which provides a changeable cosine voltage; index motor means being coupled to the wiper arms of said sine/cosine potentiometer and said index control means and being responsive to said index control means for proportionally changing the sine and cosine voltages on the wiper arms of said sine/cosine potentiometer; a first linear potentiometer including a resistive element being coupled across said voltage source and including a moveable wiper arm for providing a changeable voltage thereon; a first difference amplifier including a first input being coupled to the wiper arm of the sine resistive element of said sine/cosine potentiometer and a second input being coupled to the wiper arm of said first linear potentiometer, for providing an output signal when the input voltages thereto are at a different voltage level; a second linear potentiometer including a resistive element being coupled across said voltage source and including a moveable wiper arm for providing a changeable voltage thereon; a second difference amplifier including a first input being coupled to the wiper arm of the cosine resistive element of said sine/cosine potentiometer and a second input being coupled to the wiper arm of said second linear potentiometer, for providing an output signal when the input voltages thereto are at different voltage levels; first feedback means, being coupled to the wiper arm of the first linear potentiometer, for advancing the position of the wiper arm in response to electrical pulses thereto; second feedback means, being coupled to the wiper arm of the second linear potentiometer, for advancing the position of the wiper arm in response to electrical pulses thereto; an oscillator for providing electrical pulses; a first gate means, being coupled between said oscillator and said first feedback means and being responsive to signals from said first difference amplifier, for gating electrical pulses from said oscillator to said first feedback means during the time said difference amplifier has an output signal therefrom; a second gate means, being coupled between said oscillator and said second feedback means and being responsive to signals from said second difference amplifier, for gating electrical pulses from said oscillator to said second feedback means during the time said second difference amplifier has an output signal therefrom; output means responsive to the outputs of said first and second gate means for moving the search unit in response to pulses thereto.

Claim 16

The combination defined in claim 12 and further including pulse divider means being coupled between said gate means and said output means.

Claim 17

The combination as defined in claim 13 wherein the frequency of pulses from said pulse dividers being changeable.

Claim 18

The combination as defined in claim 12 and wherein said feedback means including electrical stepping motors.

Claim 19

The combination as defined in claim 12 wherein said index control means including: a switching means being enabled at predetermined index times; a timer circuit bEing coupled to said switching means and being enabled thereby; and a pulse oscillator being coupled being enabled thereby during the occurrence of said timing signals and being coupled to said indexing means for applying pulses thereto during index times.