Gyro pickoff apparatus to sense deviations of a vehicle axis from a gyro spin axis

Claim 2

Gyro pickoff apparatus to sense deviations of a vehicle axis from the gyro spin axis comprising: a. a silicon optical detector divided into four quadrants by mutually perpendicular X and Y planes having their intersection coincident with the vehicle axis fixed to the vehicle and providing a separate output for each quadrant; b. a light source and a mirror mounted on the gyro and arranged to reflect light from said source onto said detector such as to trace a circle centered at the center of said detector when said detector and gyro are aligned to activate said detector sequentially as said gyro rotates and adapted to activate each quadrant for equal periods of time when said gyro and detector are aligned whereby misalignment will cause said circle to shift thereby causing said detector to output signals of unequal duraTion from said four quadrants; c. resolving means to convert said four quadrant outputs into two pulse duration modulated signals proportional respectively to an X and Y deviation of the vehicle; d. first and second pulse duration modulation to digital conversion means to convert the said X and Y signals to digital outputs each of said digital outputs being proportional to the ratio of the ''''on'''' time to the total pulse cycle time of its respective pulse duration modulated input.

Claim 3

The invention according to claim 1 wherein said resolving means comprises: a. a first voltage comparator to provide said X deviation said comparator having as inputs to its positive input terminal the two detector outputs from the quadrants on one side of the Y plane and to its negative input the outputs from the two quadrants on the other side of the Y plane and providing its output to said first pulse duration modulation to digital conversion means; and b. a second voltage comparator to provide said Y deviation, said comparator having as inputs to its positive input terminal the two detector outputs from the quadrants on one side of the X plane and to its negative inputs the two detector outputs from the quadrants on the other side of the X plane and providing its output to said second pulse duration modulation to digital conversion means.

Claim 4

The invention according to claim 2 wherein each of said first and second pulse duration modulation to digital conversion means comprise: a. a phase locked loop including a pulse generator and a divide 2n counter said phase locked loop having said pulse duration modulated signal as an input and providing an output of 2n pulses for each pulse cycle; b. a 2n binary counter having the output of said phase locked-loop as an input; c. a 2n binary storage means; d). means to reset said counter at the beginning of the ''''on'''' time of each pulse duration modulated pulse; and e. means to transfer the count in said counter to said storage means at the end of the ''''on'''' time of each pulse duration modulated pulse.

Claim 5

The invention according to claim 3 wherein said phase locked loop comprises: a. a phase detector having said pulse duration modulated signal as a first input and a feedback signal as a second input; b. means to filter the output of said phase detector; c. a voltage controlled multivibrator having said filtered output as an input and providing a square wave output at a frequency proportional to the input said multivibrator output being the output of said phase locked-loop; and d. a divide by 2n binary counter having said multivibrator output as an input and providing an output pulse train as said feedback signal.

Claim 6

Gyro pickoff apparatus to sense deviations of a vehicle axis from the gyro spin axis comprising: a. a four quadrant detector fixed to the vehicle and providing a separate output for each quadrant; b. means fixed with respect to and cooperative with the gyro to activate said detector sequentially as said gyro rotates and adapted to activate each quadrant for equal periods of time when said gyro and detector are aligned and for unequal times when not aligned; c. resolving means to convert said four quadrant outputs into two pulse duration modulated signals proportional respectively to an X and Y deviation of the vehicle; d. first and second pulse duration modulation to digital conversion means to convert the said X and Y signals to digital outputs each of said digital outputs being proportional to the ratio of the ''''on'''' time to the total pulse cycle time of its respective pulse duration modulated input; e. a phase locked loop including a pulse generator and a divide by 2n counter, said phase locked loop having said pulse duration modulated signal as an input and providing an output of 2n pulses for each pulse cycle; f. a 2n binary counter having the output of said phase locked loop as an input; g. a 2n binary storage means; h. means to reset said counter at the beginning of the ''''on'''' time of each pulse duration modulated pulse; and i. means to transfer the count in said counter to said storage means at the end of the ''''on'''' time of each pulse duration modulated pulse.

Claim 7

Gyro pickoff apparatus to sense deviations of a vehicle axis from the gyro spin axis comprising: a. a four quadrant detector fixed to the vehicle and providing a separate output for each quadrant; b. means fixed with respect to and cooperative with the gyro to activate said detector sequentially as said gyro rotates and adapted to activate each quadrant for equal periods of time when said gyro and detector are aligned and for unequal times when not aligned; c. resolving means to convert said four quadrant outputs into two pulse duration modulated signals proportional respectively to an X and Y deviation of the vehicle; d. first and second pulse duration modulation to digital conversion means to convert the said X and Y signals to digital outputs each of said digital outputs being proportional to the ratio of the ''''on'''' time to the total pulse cycle time of its respective pulse duration modulated input; e. a phase locked loop including a pulse generator and a divide by 2n counter, said phase locked loop having said pulse duration modulated signal as an input and providing an output of 2n pulses for each pulse cycle; f. a 2n binary counter having the output of said phase locked loop as an input; g. a 2n binary storage means; h. means to reset said counter at the beginning of the ''''on'''' time of each pulse duration modulated pulse; and i. means to transfer the count in said counter to said storage means at the end of the ''''on'''' time of each pulse duration modulated pulse.

Claim 8

The invention according to claim 5 and further including first and second digital to analog converter means to convert said digital outputs to analog outputs.