JP4059698B2 - Inertial device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is mounted on an aircraft, rocket, or other moving body, and detects the angular velocity and acceleration of the moving body by an inertial sensor composed of a gyro and an accelerometer, and the posture angle, speed, and position of the moving body based on the angular velocity and acceleration. In particular, the present invention relates to an inertial device capable of receiving an external clock signal supplied from an external device such as an autopilot and outputting the inertial data to the external device in synchronization with the external clock signal.
[0002]
[Prior art]
In general, an inertial device is mounted on an aircraft, a rocket, or other moving body, and includes an inertial sensor and an arithmetic processing unit, and generates an attitude angle, a speed, and a position of the moving body. The posture angle, speed, and position of the moving body are referred to as inertial data of the moving body. The inertial sensor includes a gyro that detects the angular velocity of the moving body with respect to three orthogonal axes of X, Y, and Z, and an accelerometer that detects acceleration. Here, the angular velocity and acceleration detected by the inertial sensor are referred to as sensor output. The arithmetic processing unit calculates the attitude angle, speed, and position of the moving body, that is, inertia data based on the sensor output. The calculation for obtaining inertial data (attitude angle, speed and position) of the moving body based on the sensor output (angular velocity and acceleration) is called inertia calculation. The inertia calculation is an operation for calculating the posture, speed, and position of the moving body by performing an integration calculation on the sensor output. Inertia data is provided to, for example, an autopilot device (automatic piloting device) of a mobile object and used as control system control data of the mobile object. FIG. 4 and FIG. 5 are diagrams respectively showing configurations of conventionally known inertia devices. The autopilot device is an example of an external device. An external device such as an autopilot device may supply an external clock signal to the inertial device to control the operation timing of the inertial device, and has an upper relationship with the inertial device.
[0003]
The inertial device 11 (first conventional example) in FIG. 3 includes an inertial sensor 2, an up / down counter 3, an arithmetic processing unit 4, and an external connection circuit 5. Data is supplied via the data bus 7. The inertial sensor 2 is composed of a gyro for detecting angular velocity and an accelerometer for detecting acceleration, and outputs the angular velocity and acceleration about three orthogonal axes of X, Y, and Z as sensor output 101. The inertial sensor 2 has an up terminal and a down terminal corresponding to each data (angular velocity or acceleration regarding three orthogonal axes of X, Y, and Z) in the sensor output 101, and when the data is a positive value The number of pulses representing the magnitude of the data is outputted from the up terminal, and when the data is a negative value, the number of pulses representing the magnitude of the data is outputted from the down terminal.
[0004]
The up / down counter 3 includes an up count input terminal and a down count input terminal corresponding to the up terminal and the down terminal of the inertial sensor 2, respectively. The up terminal of the inertial sensor 2 is connected to the upcount input terminal, and the down terminal of the inertial sensor 2 is connected to the downcount input terminal. The up / down counter 3 adds (counts up) the count value by the number of pulses input to the up-count input terminal at the timing of the clock signal 104 supplied from the arithmetic processing unit 4, and is input to the down-count input terminal. The count value is subtracted (counted down) by the number of pulses counted. This counting process in the up / down counter 3 is referred to as an up / down counting process. The up / down counting process is a kind of integration process because the sensor output 101 is counted in the cycle of the clock signal 104. The period of the clock signal 104 is, for example, about 1 msec. The up / down counter processing output 102 of the up / down counter 3 is sent to the arithmetic processing unit 4. The arithmetic processing unit 4 performs inertia calculation for the up / down count processing output 102 and generates inertia data 103. The inertia calculation in the calculation processing unit 4 includes integration calculation of the up / down count process output 102. The inertia data 103 is supplied to the higher-level external device 6 via the external connection circuit 5 and the data bus 7.
[0005]
In the conventional example of FIG. 3, the up / down counting process in the up / down counter 3 and the inertial calculation process in the arithmetic processing unit 4 are performed at an independent timing that is not related to the clock signal of the host external device 6, that is, The processing operation in the host external device 6 is performed asynchronously. Therefore, it is unavoidable that the processing timing between the inertial device 11 and the high-order external device 6 is shifted. When the high-order external device 6 receives the inertial data 103, the inertial data 103 is acquired at any time. The host external device 6 cannot accurately know whether the moving body is physically moving. Therefore, in the inertial apparatus of FIG. 3, an error between the inertial data 103 and the physical motion state of the moving body is unavoidable.
[0006]
The inertial device 12 (second conventional example) in FIG. 4 is a conventional example intended to eliminate this drawback, and each component is the same as that in the device in FIG. The inertial device 12 in FIG. 4 differs from the inertial device 11 in FIG. 3 in that an external clock signal 105 output from the host external device 6 is introduced into the inertial device 12. The external clock signal 105 is input to the arithmetic processing unit 4 of the inertial device 12, is waveform-shaped by the arithmetic processing unit 4, and becomes a clock signal 104 having the same timing. The clock signal 104 is supplied to the up / down counter 3 and controls the operation timing of the up / down counter 3 in the same manner as described with reference to FIG. The frequency (pulse repetition frequency) of the external clock signal 105 and the clock signal 104 is, for example, 1 kHz.
[0007]
In FIG. 4, the sensor output 101 of the inertial sensor 2 is input to the up / down counter 3 and subjected to an up / down count process for each period based on the clock signal 104. The up / down counter processing output 102 of the up / down counter 3 is sent to the arithmetic processing unit 4. The arithmetic processing unit 4 performs inertia calculation processing on the up / down count processing output 102 at the timing of the external clock signal 105 to generate inertia data 103. This inertia calculation includes an integration calculation of an up / down count output, similar to the calculation in FIG. In the inertial device 12 of FIG. 4, the start and end of the integration period of the integration calculation is the timing of the external clock signal 105. The inertial data 103 is supplied to the higher-level external device 6 via the external connection circuit 5 and the data bus 7 as in the case of the conventional example of FIG.
[0008]
As described for the up / down counter 3 in the inertial device 11 in FIG. 3, the counting process in the up / down counter 3 is a kind of integration process, and the arithmetic processing unit 4 also performs the integration process. The counting process in the counter 3 is a short time count of about 1 msec, and the integration process in the arithmetic processing unit 4 is performed by integrating the up / down count process output 102 for a longer time. The arithmetic processing unit 4 receives the external clock signal 105, generates an internal clock signal obtained by dividing the frequency of the external clock signal 105, and performs integration processing at the timing of the internal clock signal.
[0009]
In the conventional example of FIG. 4, the processing operations of the up / down counter 3 and the arithmetic processing unit 4 are synchronized with the external clock signal 105 of the upper external device 6, so that the inertial data 103 waits at the upper upper external device 6. Is supplied to the host external device 6. Therefore, in the inertial device 12 (second conventional example) shown in FIG. 4, the disadvantages of the inertial device 11 (first conventional example) shown in FIG. 3 are avoided.
[0010]
[Problems to be solved by the invention]
In the conventional example described above, in the case of the second conventional example proposed to compensate for the disadvantages of the first conventional example, the processing operations of the up / down counter 3 and the arithmetic processing unit 4 in the inertial device 12 are as follows. The time difference between the inertial data 103 output from the inertial device 12 and the data reception timing of the high-order external device 6 is avoided for the time being, in synchronization with the external clock signal 105 of the high-order external device 6. The host external device 6 can accurately know at which point the inertial data 103 represents the physical motion state of the mobile object acquired. However, the inertia calculation process in the calculation processing unit 4 includes an integral calculation, and the time interval from the start to the end of the integral calculation is defined by the external clock signal 105. Therefore, if the cycle of the external clock signal 105 varies, There is a drawback that an error occurs in the integration time interval of the integration operation, and the error in the integration time interval directly leads to deterioration in accuracy of the inertial data 103 (attitude angle, speed, and position) due to the inertia calculation in the arithmetic processing unit 4.
[0011]
Accordingly, an object of the present invention is to eliminate the above-mentioned drawbacks, to supply inertial data synchronized with an external clock signal to an external device, and to output high-precision inertial data even if the cycle of the external clock signal varies. It is to provide an inertial device.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides the following means.
[0013]
(1) an inertial sensor for detecting the angular velocity and acceleration of the moving body, an arithmetic means for generating inertial data including the posture angle, speed and position of the moving body by inertial calculation based on the output of the inertial sensor, and a data bus An inertial device comprising an external connection circuit connected to an external device and sending the inertial data to the external device via the data bus ,
It said calculation means receives an external clock signal output from said external device, performs the inertial operation in synchronization with the external clock signal, the said inertial data generated by inertial operation in synchronism with the clock signal Transmit to the external device via the external connection circuit and data bus ,
In the inertial apparatus including the integral calculation of the output of the inertial sensor, the inertial calculation includes:
The arithmetic means receives external clock signal repetition period data representing a repetition period of the external clock signal from the external device via the data bus and the external connection circuit, and is represented by the external clock signal repetition period data. An inertial device that performs the integration operation based on a repetition period of an external clock signal.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, the inertial device of the present invention will be described more specifically with reference to an embodiment of the present invention.
[0015]
FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. As shown in FIG. 1, the inertial device 1 of this embodiment includes an inertial sensor 2, an up / down counter 3, an arithmetic processing unit 4, and an external connection circuit 5. 2 (a), (b), (c), (d), (e), and (f) are timing charts of the respective signals, operations, and data output in the operation processing unit 4.
[0016]
In FIG. 1, a sensor output 101 (corresponding to the aforementioned inertial sensor output) detected by the inertial sensor 2 is input to the up / down counter 3 and up / down at the timing of the clock signal 104 supplied from the arithmetic processing unit 4.・ Count processing is performed. The operation of the inertial sensor 2 and the up / down counter 3 is the same as described with reference to FIG. The up / down count processing output 102 output from the up / down counter 3 is input to the arithmetic processing unit 4. In the arithmetic processing unit 4, the inertia calculation processing is performed for the up / down count processing output 102 as in the conventional inertial device of FIGS. 3 and 4. The inertial device 1 of the present embodiment is characterized in that external clock cycle data 106 representing the cycle of the external clock signal 105 is supplied from the higher-level external device 6 to the arithmetic processing unit 4 via the data bus 7 and the external connection circuit 5. In the point. The external clock cycle data 106 is obtained by measuring the repetition cycle of the external clock signal 105 with high accuracy in the host external device 6.
[0017]
The arithmetic processing unit 4 can obtain the accurate inertia data 103 excluding the influence of the frequency variation of the external clock signal 105 by using the external clock cycle data 106 as the integration time of the integral calculation in the inertia calculation. In the arithmetic processing unit 4, the repetition cycle of the external clock signal 105 is known from the external clock cycle data 106, and the time-integration of the up / down count processing output 102 is performed based on the time based on the external clock cycle data 106 to generate the inertia data 103. . The accuracy of the inertial data 103 obtained by time integration of the up / down count processing output 102 is substantially the same as the accuracy of the repetition cycle of the external clock signal 105, that is, the external clock cycle data 106. The inertia data 103 is transmitted to the higher-level external device 6 through the external connection circuit 5 and the data bus 7.
[0018]
With reference to FIG. 2, the arithmetic processing in the arithmetic processing unit 4 will be described more specifically. FIG. 2A shows the timing of the external clock signal 105. P1, P2,... Pn represent clock pulses in the external clock signal 105, respectively. The repetition period Δt of the external clock signal 105 is Δt 0, Δt 1... Δtn, respectively. FIG. 4B shows the timing at which the external clock cycle data 106 is supplied to the arithmetic processing unit 4. External clock period data 106, the repetition period [Delta] t0, .DELTA.t1 data · · · · · .DELTA.tn is input to the T _10, T ₁₁ ····· T arithmetic processing unit 4 in the time zone _1n. As shown in this figure, data Δt 0, Δt 1... Δtn−1 representing the repetition period of the external clock signal 105 are the initial time zones T ₁₀ and T ₁₁ of the external clock period data 106 of the next period. ... _Is supplied to the arithmetic processing unit 4 at T _1n-1 .
[0019]
FIG. 2C shows the timing at which the up / down count processing output 102 supplied from the up / down counter 3 is taken into the arithmetic processing unit 4 to calculate highly accurate acceleration and angular velocity data. The arithmetic processing unit 4 calculates acceleration and angular velocity data in a time zone of T ₂₀ , T ₂₁ ... T _2n−1 . The calculation performed in each time zone of timing T ₂₀ , T ₂₁ ... T _2n−1 in FIG. 2C is a repetition cycle Δt of the external clock signal 105 represented by the external clock cycle data 106. It includes an operation for dividing the up / down count processing output 102. By this division operation, acceleration and angular velocity excluding the influence of the fluctuation of the repetition period Δt in the external clock signal 105 can be obtained. FIG. 2D shows the timing at which acceleration and angular velocity data are passed to the next inertial calculation processing step inside the calculation processing unit 4. That is, in the arithmetic processing unit 4, highly accurate acceleration and angular velocity data obtained in the time zone of T ₂₀ , T ₂₁ ... T _2n−1 are T ₃₀ , T _{31. It} is passed to the processing step of inertia calculation in the time zone of _2n-1 .
[0020]
FIG. 2E shows the timing of inertia calculation processing in the calculation processing unit 4. In the inertia calculation process, inertia data including the posture, speed, and position of the moving body is calculated based on the acceleration and angular velocity data in the five periods of the repetition period Δt of the external clock signal 105. The arithmetic processing unit 4 calculates the posture, speed, and position in the time zone T _{C 1} based on the acceleration and angular velocity data passed in T ₃₀ , T ₃₁ , T ₃₂ , T ₃₃ , and T ₃₄ . As described above, the acceleration and angular velocity passed from the acceleration and angular velocity calculation steps to T ₃₀ , T ₃₁ , T ₃₂ , T ₃₃ , and T ₃₄ are the actual repetitions of repetition periods Δt 0, Δt 1, Δt 2, Δt 3, and Δt 4. Since the value is calculated based on the period data, an error due to time fluctuation in the repetition period of the external clock signal 105 is excluded. Further, the inertia calculation in the time zone T _{C 1} includes an integration calculation for time integration of these accelerations and angular velocities, but data of repetition times (Δt 0, Δt 1, Δt 2, Δt 3 and Δt 4) indicated by the external clock cycle data 106. Therefore, in the posture, speed, and position of the moving body obtained by inertia calculation, errors due to time fluctuations in the repetition cycle of the external clock signal 105 are excluded. Therefore, the inertial data (attitude, speed, and position) calculated in the time zone T _{C 1} is highly accurate data excluding the influence of the fluctuation of the repetition period Δt in the external clock signal 105. FIG. 2 (f) shows the timing for outputting the inertia data obtained by the inertia calculation process to the external connection circuit 5 in the time zones T _{C 0} , T _{C 1} . T _{OUT 0} and T _{OUT 1} represent time zones in which the inertial data calculated in the time zones T _{C 0} and T _{C 1} are output, respectively. The external connection circuit 5 transfers the inertial data 103 received from the arithmetic processing unit 4 to the upper external device 6 via the data bus 7 as it is.
[0021]
As described with reference to FIG. 2, the arithmetic processing unit 4 performs time integration of the up / down count processing output 102 with the time indicated by the external clock cycle data 106 (FIG. 2B). Since the time data in the time integration is accurate, the arithmetic processing unit 4 can calculate accurate inertia data excluding the influence of the error of the repetition period of the external clock signal 105.
[0022]
In addition, even if the fluctuation of the repetition period of the external clock signal 105 is caused by jitter of the repetition period of the external clock signal 105 and the jitter is a relatively large value, in this embodiment, the external clock signal 105 Since the data of the repetitive cycle is received every cycle, the inertia data 103 does not have the influence of the jitter.
[0023]
As apparent from the timing chart of FIG. 2, the inertia data 103 output from the inertial device 1 of the present embodiment is the timing of FIG. 2 (f) associated with the timing of the external clock 105 of FIG. 2 (a). Is supplied to the host external device 6. As described above, the processing operations of the up / down counter 3 and the arithmetic processing unit 4 are synchronized with the external clock signal 105 of the higher-order external device 6, so that the inertial data 103 is sent to the higher-order external device 6 at a timing waiting in the higher-order external device 6. Supplied against. Therefore, there is no deviation in the processing timing between the devices of the inertial device 1 and the higher-order external device 6, and when the higher-order external device 6 receives the inertial data 103, the mobile object acquired by the inertial data 103 at any point in time The higher-order external device 6 can accurately know whether the physical motion state is. Therefore, by employing the inertial device of FIG. 1, the inertial data 103 accurately represents the physical motion state of the moving body in real time, and the host external device 6 such as an autopilot can appropriately control the moving body.
[0024]
【The invention's effect】
As specifically described above with reference to the embodiments, according to the present invention, inertia data synchronized with an external clock signal can be supplied to an external device, and even if the period of the external clock signal varies, high accuracy is achieved. It is possible to provide an inertial device capable of outputting the inertial data.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of the present invention.
FIG. 2 is a timing diagram of each unit signal, calculation, and data output in the calculation processing unit 4 of FIG. 1;
FIG. 3 is a block diagram showing a first conventional example.
FIG. 4 is a block diagram showing a second conventional example.
[Explanation of symbols]
1, 11, 12 Inertial device 2 Inertial sensor 3 Up / down counter 4 Arithmetic processing unit 5 External connection circuit 6 Host external device 7 Data bus 101 Sensor output 102 Up / down count processing output 103 Inertial data 104 Clock signal 105 External clock signal 106 external clock period data P1, P2 ····· Pn, Pn + 1 external clock signal 105 each clock pulse Δt0 in, .DELTA.t1 · · · · · .DELTA.tn repetition period T ₁₀ in the external clock signal 105, T ₁₁ · · · .. Data timings T ₂₀ , T ₂₁ in the T _1n-1 external clock cycle data 106... Time zones T ₃₀ , T ₃₁ for calculating acceleration and angular velocity data in the T _2n-1 calculation processing unit 4 in ··· T _2n-1 processing section _{4, T 20, T 21 ·····} T 2n-1 of the high-precision acceleration obtained in the time period Time zone and passes data of the angular velocity to the processing step of the inertial operation T _{C 0,} T _{C 1} processing unit posture of the moving body at 4, the time period T _OUT for calculating the inertial data including the speed and position _0, T _{OUT 1} Time zone for outputting inertial data calculated in time zones T _{C 0} and T _{C 1}

Claims (1)

An inertial sensor that detects the angular velocity and acceleration of the moving body, an arithmetic means that generates inertial data including the attitude angle, speed, and position of the moving body by inertial calculation based on the output of the inertial sensor, and an external device via a data bus An inertial device comprising: an external connection circuit connected to send the inertial data to the external device via the data bus ;
It said calculation means receives an external clock signal output from said external device, performs the inertial operation in synchronization with the external clock signal, the said inertial data generated by inertial operation in synchronism with the clock signal Transmit to the external device via the external connection circuit and data bus ,
In the inertial apparatus including the integral calculation of the output of the inertial sensor, the inertial calculation includes:
The arithmetic means receives external clock signal repetition period data representing a repetition period of the external clock signal from the external device via the data bus and the external connection circuit, and is represented by the external clock signal repetition period data. An inertial device that performs the integration operation based on a repetition period of an external clock signal.

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