Inertial rate sensor and method with built-in testing
First Claim
Patent Images
1. In an inertial rate sensor:
- a vibratory rate sensing element, a drive circuit for applying a drive signal to the rate sensing element, an output terminal, a pickup circuit coupled to the rate sensing element for providing a rate output signal at the output terminal corresponding to movement of the rate sensing element, a memory in which compensation values are stored in the form of digital data, means for communicating with an external programming computer through the output terminal to access data stored in the memory, a digital-to-analog converter for converting data retrieved from the memory to analog signals, means for calibrating the rate sensor with the analog signals, means for monitoring conditions at different points within the rate sensor to detect occurrence of a failure, and means for applying a signal of predetermined character to the output terminal in the event that occurrence of a failure is detected.
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Abstract
Inertial rate sensor and method in which in which a single output terminal is utilized for delivering a rate output signal during normal operation, interfacing with an external computer during a programming mode, and for providing a warning in the event of a failure. Access to the programming mode is permitted only when a predetermined sequence of conditions is met, and accidental initiation of the programming mode is virtually impossible. Compensation data is stored redundantly at two locations in an internal memory, and the data is read from both locations and compared to verify its validity. Signals are monitored at different points to detect the occurrence of failures.
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Citations
26 Claims
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1. In an inertial rate sensor:
- a vibratory rate sensing element, a drive circuit for applying a drive signal to the rate sensing element, an output terminal, a pickup circuit coupled to the rate sensing element for providing a rate output signal at the output terminal corresponding to movement of the rate sensing element, a memory in which compensation values are stored in the form of digital data, means for communicating with an external programming computer through the output terminal to access data stored in the memory, a digital-to-analog converter for converting data retrieved from the memory to analog signals, means for calibrating the rate sensor with the analog signals, means for monitoring conditions at different points within the rate sensor to detect occurrence of a failure, and means for applying a signal of predetermined character to the output terminal in the event that occurrence of a failure is detected.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. In a method of sensing inertial rate, the steps of:
- applying a drive signal to a vibratory element in a rate sensor to produce oscillation, monitoring signals produced by movement of the vibratory element to provide a rate signal, delivering the rate signal to an output terminal, storing compensation values in a memory in the form of digital data, communicating with an external programming computer through the output terminal to access data stored in the memory, converting data retrieved from the memory to analog signals, calibrating the rate sensor with the analog signals, monitoring conditions at different points within the rate sensor to detect occurrence of a failure, and applying a signal of predetermined character to the output terminal in the event that occurrence of a failure is detected.
- View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. In an inertial rate sensor:
- a vibratory rate sensing element, a drive circuit for applying a drive signal to the rate sensing element, an output terminal, a pickup circuit coupled to the rate sensing element for providing a rate signal corresponding to movement of the rate sensing element, a memory in which digital data is stored, an output stage capable of operating in a normal mode in which the rate signal is passed to the output terminal and in a programming mode in which an external computer can interface with the memory through the output terminal, and means for preventing the output stage from entering the programming mode unless the following conditions are met;
the power supply voltage is raised to an elevated level and maintained at the elevated level for a predetermined period of time, a first access code is applied through the output terminal, and a second access code is applied to the memory to initiate a read/write sequence.
- a vibratory rate sensing element, a drive circuit for applying a drive signal to the rate sensing element, an output terminal, a pickup circuit coupled to the rate sensing element for providing a rate signal corresponding to movement of the rate sensing element, a memory in which digital data is stored, an output stage capable of operating in a normal mode in which the rate signal is passed to the output terminal and in a programming mode in which an external computer can interface with the memory through the output terminal, and means for preventing the output stage from entering the programming mode unless the following conditions are met;
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18. In an inertial rate sensor:
- a vibratory rate sensing element, a drive circuit for applying a drive signal to the rate sensing element, an output terminal, a pickup circuit coupled to the rate sensing element for providing a rate signal corresponding to movement of the rate sensing element, a memory in which digital data is stored, means for monitoring conditions within the rate sensor to detect occurrence of a failure in the rate sensor, and an output stage capable of operating in a normal mode in which the rate signal is passed to the output terminal, a programming mode in which an external computer can interface with the memory through the output terminal, and a failure mode in which the output terminal is held at a predetermined voltage level in the event that occurrence of a failure is detected.
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19. In a method of sensing inertial rate, the steps of:
- applying a drive signal to a vibratory element in a rate sensor to produce oscillation, monitoring signals produced by movement of the vibratory element to provide a rate signal, storing digital data in a memory, programming an output stage for operation either in a normal mode in which the rate signal is passed to an output terminal or in a programming mode in which an external computer can interface with the memory through the output terminal, with the output stage being permitted to enter the programming mode only if the following conditions are met;
power supply voltage is raised to an elevated level and maintained at the elevated level for a predetermined period of time, a first access code is applied through the output terminal, and a second access code is applied to the memory to initiate a read/write sequence.
- applying a drive signal to a vibratory element in a rate sensor to produce oscillation, monitoring signals produced by movement of the vibratory element to provide a rate signal, storing digital data in a memory, programming an output stage for operation either in a normal mode in which the rate signal is passed to an output terminal or in a programming mode in which an external computer can interface with the memory through the output terminal, with the output stage being permitted to enter the programming mode only if the following conditions are met;
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20. In a method of sensing inertial rate, the steps of:
- applying a drive signal to a vibratory element in a rate sensor to produce oscillation, monitoring signals produced by movement of the vibratory element to provide a rate signal, storing digital data in a memory, monitoring signals to detect occurrence of a failure in the rate sensor, and programming an output stage to operate in a normal mode in which the rate signal is passed to an output terminal, a programming mode in which an external computer can interface with the memory through the output terminal, or a failure mode in which the output terminal is held at a predetermined voltage level in the event that a failure is detected.
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21. In an inertial rate sensor:
- a vibratory rate sensing element, a drive circuit for applying a drive signal to the rate sensing element, a pickup circuit coupled to the rate sensing element for providing a rate signal corresponding to movement of the rate sensing element, a memory in which compensation data is stored in the form of digital words each of which is stored in two different locations, means for reading the data from both locations and comparing the two words to verify the data, means for interpreting the data as having a positive sign if the two words are identical and as having a negative sign if the two words are complementary, means for selecting a compensation value in accordance with the sign of the data, and means for combining the compensation value with the rate signal.
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22. In a method of sensing inertial rate, the steps of:
- applying a drive signal to a vibratory rate sensing element to produce oscillation, monitoring signals produced by movement of the rate sensing element to provide a rate signal, storing compensation data in a memory in the form of digital words each of which is stored in two different locations, reading the data from both locations and comparing the two words to verify the data, interpreting the data as having a positive sign if the two words are identical and as having a negative sign if the two words are complementary, selecting a compensation value in accordance with the sign of the data, and combining the compensation value with the rate signal.
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23. In an inertial rate sensor:
- a vibratory rate sensing element, a drive circuit for applying a drive signal to the rate sensing element, a pickup circuit coupled to the rate sensing element for providing a rate signal corresponding to movement of the rate sensing element, a memory in which compensation values are stored in the form of digital data, means for converting data retrieved from the memory to analog compensation signals, means for adjusting the rate signal in accordance with the compensation signals, a temperature sensor for providing an analog temperature signal, means including an analog-to-digital converter and successive approximation logic for converting the analog temperature signal to a digital signal for use in addressing the memory to retrieve temperature compensation data.
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24. In a method of sensing inertial rate, the steps of:
- applying a drive signal to a vibratory rate sensing element to produce oscillation, monitoring signals produced by movement of the rate sensing element to provide a rate signal, storing compensation values in a memory in the form of digital data, converting data retrieved from the memory to analog compensation signals, adjusting the rate signal in accordance with the compensation signals, monitoring temperature with an analog temperature sensor, converting an analog temperature signal to a digital signal, and addressing the memory in accordance with the digital signal to retrieve temperature compensation data.
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25. In an inertial rate sensor:
- a vibratory rate sensing element, a drive circuit for applying a drive signal to the rate sensing element, a pickup circuit coupled to the rate sensing element for providing a rate signal corresponding to movement of the rate sensing element, a temperature sensor for providing an analog temperature signal, means including an analog-to-digital converter and successive approximation logic for converting the analog temperature signal to a digital temperature signal, a digital-to-analog converter for converting the digital temperature signal to an analog feedback signal, means for combining the feedback signal with the signal from the temperature sensor to provide a residual error signal, and means for monitoring the residual error signal to verify the accuracy of the conversions.
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26. In a method of sensing inertial rate, the steps of:
- applying a drive signal to a vibratory rate sensing element to produce oscillation, monitoring signals produced by movement of the rate sensing element to provide a rate signal, monitoring temperature with an analog temperature sensor, converting an analog temperature signal to a digital temperature signal, converting the digital temperature signal to an analog feedback signal, combining the feedback signal with the signal from the temperature sensor to provide a residual error signal, and monitoring the residual error signal to verify the accuracy of the conversions.
Specification