High speed digital tracking system

Claim 3

The apparatus of claim 1 wherein said tracking control means further includes, first integrator means for integrating under control of a control signal an acceleration signal d2F(y)/dt2 to form the velocity signal dF(y)/dt, and control signal generator means for generating said control signal from said error signal F(x,y) to control the direction of integration of said first integrator means.

Claim 4

The apparatus of claim 2 wherein said control signal generator includes means for generating said control signal by forming the electrical analog of each term of the control signal, CS, defined by the following equation: CS F(x,y) + dF(x,y)/dt.

Claim 5

The apparatus of claim 2 wherein said control signal generator includes means for generating said control signal by forming the electrical analog of each term of the control signal, CS, defined by the following equation:

Claim 6

The apparatus of claim 2 wherein said first integrator means includes a digital velocity counter for accumulating and storing a velocity count and wherein said apparatus includes, means providing output pulses having a frequency representing the magnitude of the velocity count to thereby form said velocity signal dF(y)/dt.

Claim 7

The apparatus of claim 5 wherein said means for providing includes, a digital frequency counter having a plurality of stages exhibiting output pulses of different frequencies, and a frequency selector for decoding the contents of said digital counter to select appropriate ones of said stages to provide output pulses at a frequency representing the magnitude of said velocity count.

Claim 8

The apparatus of claim 1 wherein A. said tracking control means further includes: an acceleration source generating an acceleration signal d2F(y)/dt2 in the form of a constant frequency first pulse train, a first integrator means for integrating said acceleration signal d2F(y)/dt2 to form said velocity signal dF(y)/dt, said first integrator means including first bidirectional counter means for counting the pulses in said first pulse train in an up or down direction to accumulate and store a count representing dF(y)/dt, control signal generator means for generating a control signal in the form zero detector means for generating a zero detect signal in response to a zero count in said first bidirectional counter means, integration control means for controlling the counting direction of said first bidirectional counter means in response to said control signal, and for providing a sign signal identifying the positive or negative character of the count in said first bidirectional counter, and means providing output pulses to form a second pulse train exhibiting a frequency proportional to the count in said first bidirectional counter, and B. said generator means is a second integrator including second bidirectional counter means to accumulate and store a count proportional to F(y) by counting the pulses in said second pulse train in an up or down direction as determined by said sign signal.

Claim 9

The apparatus of claim 7 further including a clock having a frequency (N/2)F, wherein said first bidirectional counter has a count range R1 and is stepped by said clock at frequency (N/2) (F)/10 to provide said first pulse train at frequency (N/2) (F)/(10) (R1). and wherein said second counter means has a count range R2 for storing a digital count n representing F(y) and is stepped to change the value of n at discrete frequencies, between 0 and (N/2) (F)/10 in whole-number multiples of (N/2) (F)/(10) (R1).

Claim 10

The apparatus of claim 8 wherein said generator means further includes means for generating a pulse-width modulated signal at a fundamental frequency (N/2) (F)/R2 where the pulse width is proportional to n/N where N equals 2 X (2) and n ranges from 0 to 2 X (R2).

Claim 11

The apparatus of claim 9 wherein said frequency (N/2) (F) equals 107 bits/sec and wherein said first count range R1 is 103 thereby establishing said first pulse train at a frequency of 103 bits/sec and thereby defining discrete frequencies as whole-number multiples 103 bits/sec whereby the acceleration d2F(y)/dt2 is limited by 106 bits/sec 2 and the velocity dF(y)/dt is limited by 106 bits/sec.

Claim 12

The apparatus of claim 10 wherein said count range R2 is 103 so as to produce a fundamental frequency of 104Hz where N equals 2 X 103.

Claim 13

The apparatus of claim 2 wherein said comparing means is a position measuring transformer, wherein said F(x) function is the space position, x, of two relatively movable members of said transformer, wherein said F(y) function is an electrical angle, y, supplied to said transformer in the form of electrical sin(y) and cos(y) signals, and wherein said error signal is in the form of sin(y- x).

Claim 14

The apparatus of claim 12 wherein said control signal generator includes means for differentiating said error signal sin(y- x) to form a stability term (dy/dt - dx/dt) (cos y- x) and means for adding said stability term to a positional error term constituted by said error signal sin(y- x) to form an analog signal, CS, of the form, CS sin(y- x) + (dy/dt - dx/dt) cos (y- x).

Claim 15

The apparatus of claim 13 further including a threshold detector for forming said control signal as a binary 1 or 0 as a function of the plus or minus level, respectively, of said analog signal CS.

Claim 16

The apparatus of claim 13 wherein said control signal generator further includes means for squaring said stability term to form a response term, and wherein said means for adding forms an analog signal, CS, from the weighted sum of the positional error, stability, and response terms as follows:

Claim 17

The apparatus of claim 11 further including a threshold detector for forming said control signal as a binary 1 or 0 as a function of the plus or minus level, respectively, of said analog signal CS.

Claim 18

Tracking apparatus including a position measuring device having a stationary element and having a movable element, said elements being inductively related, said position measuring device supplying an error signal depending on a comparison of the relative displacement of said inductively related elements with an input of trigonometrically related signals to said position measuring device, means for generating said trigonometrically related signals in response to said error signal, said error signal being operative to produce a number of pulses to change the values of said trigonometrically related signals an amount representing the displacement of said movable element, said change being in a direction reducing said error signal to a small value, said number of pulses being coUnted and stored for providing a digital readout, characterized in that means are provided for modifying said generation of trigonometrically related signals in accordance with a control signal which comprises the summation of (a) said error signal, (b) the rate of change of said error signal with respect to time, and (c) a function of said rate of change of said error signal, whereby there is a reduction of lag between said digital readout and the instantaneous position of said movable element when the latter is in motion.

Claim 19

Tracking apparatus including a position measuring device having a stationary element and having a movable element, said elements being inductively related, said position measuring device supplying an error signal depending on a comparison of the relative displacement of said inductively related elements with an input of trigonometrically related signals to said position measuring device, means for generating said trigonometrically related signals in response to said error signal, said error signal being operative to produce a number of pulses to change the values of said trigonometrically related signals an amount representing the displacement of said movable element, said change being in a direction reducing said error signal to a small value, said number of pulses being coUnted and stored for providing a digital readout, characterized in that means are provided for modifying said generation of trigonometrically related signals in accordance with a control signal which comprises the summation of (a) said error signal, (b) the rate of change of said error signal with respect to time, and (c) a function of said rate of change of said error signal, whereby there is a reduction of lag between said digital readout and the instantaneous position of said movable element when the latter is in motion.

Claim 20

Tracking apparatus including a position measuring device having relatively movable elements, said position measuring device supplying an error signal depending on a comparison of the relative displacement of said elements with an input of trigonometrically related signals to said position measuring device, means for generating said trigonometrically related signals in response to said error signal, said error signal being operative to produce a number of pulses to change the values of said trigonometrically related signals an amount representing the displacement of said relatively movable elements, said change being in a direction reducing said error signal to a small value, said number of pulses being counted and stored for providing a digital readout, characterized in that means are provided for modifying said generation of trigonometrically related signals in accordance with a control signal which comprises the summation of (a) said error signal, and (b) the rate of change of said error signal with respect to time, whereby there is a reduction of lag between said digital readout and the instantaneous position of said relatively movable elements when in motion.

Claim 21

Tracking apparatus including a position measuring device having relatively movable elements, said position measuring device supplying an error signal depending on a comparison of the relative displacement of said elements with an input of trigonometrically related signals to said position measuring device, means for generating said trigonometrically related signals in response to said error signal, said error signal being operative to produce a number of pulses to change the values of said trigonometrically related signals an amount representing the displacement of said relatively movable elements, said change being in a direction reducing said error signal to a small value, said number of pulses being counted and stored for providing a digital readout, characterized in that means are provided for modifying said generation of trigonometrically related signals in accordance with a control signal which comprises the summation of (a) said error signal, and (b) the rate of change of said error signal with respect to time, whereby there is a reduction of lag between said digital readout and the instantaneous position of said relatively movable elements when in motion.

Claim 22

A digital readout apparatus comprising, a measuring transducer exhibiting a space position and receiving an input which produces an error signal as a function of the difference between the input and the space position, means responsive to the error signal and the first derivative with respect to time of the error signal to cause the input to reduce, at different rates, the error signal toward zero.

Claim 23

A digital readout apparatus comprising, a measuring transducer exhibiting a space position and receiving an input which produces an error signal as a function of the difference between the input and the space position, means responsive to the error signal and the first derivative with respect to time of the error signal to cause the input to reduce, at different rates, the error signal toward zero.

Claim 24

The digital readout apparatus of claim 19 wherein said means further includes a first counter for digitally tracking the first derivative with respect to time of said space position and a second counter apparatus for counting at a rate controlled by said first counter to form said input as a measure of said space position.

Claim 25

The digital readout apparatus of claim 20 wherein said second counter divides each cycle of said measuring transducer into N parts and wherein said control means is operative to track said space position by storing a digital value n as a measure of the space position which is accurate to within one part of the N parts.

Claim 26

The digital readout apparatus of claim 21 wherein said control means causes said second counter means to digitally oscillate with a one bit oscillation to define the value n as a static null measurement of the space position whenever the space position is not changing.

Claim 27

The digital readout apparatus of claim 21 wherein said control means causes the rate of change of said digital value n to change in a manner which tracks and oscillates about the rate of change of said space position whereby n is a dynamic null measurement of said space position.