KR102044508B1 - Method and apparatus for providing navigation data in inertial navigation system - Google Patents

Abstract

The present invention relates to a variable navigation operation and navigation information providing technology of the inertial navigation information calculation unit, and determines the radio wave transmission and reception period of the variable navigation information, and transmits a timing signal for determining the radio wave transmission and reception period to the RF transceiver; A variable timing scheduling unit for radiating radio waves through an RF antenna at a radio transmission and reception period; A timing controller for calculating a delay time between the timing signal and the radio wave emission time of the RF antenna and determining an operation period of the variable navigation information based on the delay time; An inertial navigation information calculator configured to periodically perform calculation of the variable navigation information in synchronization with a heartbeat signal generated based on the operation period; And an image processor configured to process the synchronized image based on the calculation result of the variable navigation information.

Description

Navigation information providing device and method thereof of inertial navigation system {METHOD AND APPARATUS FOR PROVIDING NAVIGATION DATA IN INERTIAL NAVIGATION SYSTEM}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation information providing technology of an inertial navigation system, and more particularly, to an apparatus and an inertial navigation system having a variable propagation period or a variable operation period, such as a Synthetic Array Radar (SAR) image. The present invention relates to a technique suitable for improving the image accuracy of SAR by matching the navigation information calculation cycle of the (Inertial Measurement Unit) and the navigation information provision period.

Inertial navigation systems and radars have long been a necessity for navigation, and the technological complexity and difficulty of the inertial systems have been developed in independent areas.

A SAR is a device for synthesizing an image using a radio signal. The SAR transmits radio waves at scheduled time intervals and collects reflected signals for a predetermined time to form an image. The propagation interval through the antenna varies with time scheduling and typically varies from a few hundred Hz to several kilo Hz.

An inertial navigation system uses inertial sensors (accelerometers, gyroscopes, etc.) to calculate the position, velocity, and attitude of the platform in real time with a fixed calculation cycle.

In order to synthesize the SAR image, the antenna attitude value during radio wave transmission and reception must be compensated accurately. For this, the attitude information is input from a separate inertial navigation system in real time, or the inertial measurement device is attached to the SAR antenna. Sometimes posture information is obtained.

This structure, which has been applied up to now, does not coincide with the timing of antenna radio wave transmission and the position value transmitted from the inertial navigation system or the inertial measurement unit. Therefore, various techniques such as correcting the attitude information by interpolation are used. Has been applied.

Even if correction techniques are used to resolve visual synchronization discrepancies, visual synchronization (time coincidence) of SAR and inertial navigation system (inertial measurement unit) operating according to independent operation cycle is structurally impossible. There is no compensating method for high frequency posture fluctuations that occur faster than the calculation period or communication period of the inertial measuring instrument. Therefore, the posture error caused by the time synchronization mismatch and the high frequency posture error generated during the calculation period cause the SAR error.

Another factor that causes SAR video errors is due to the variable SAR propagation period. The SAR continuously varies the radio transmission cycle for optimal image information acquisition. Therefore, a time synchronization mismatch occurs with an inertial navigation system (inertial measurement unit) that periodically calculates navigation information, causing an image error.

Korea Registered Patent No. 10-1468548 (registered Nov. 27, 2014)

In an embodiment of the present invention, an integrated design of a SAR and an inertial navigation system for improving image accuracy of a radar having a variable radio wave transmission / reception period (or a variable operation period), for example, SAR, is implemented. This paper proposes a technique for calculating and varying a calculation cycle of navigation information such as position, speed, and attitude of an inertial navigation system (inertial measurement device) and a navigation information providing technology synchronized with the synchronous navigation system.

In the practice of the present invention, the SAR and the inertial navigation system are designed to be integrated to solve fundamental visual synchronization mismatch and high frequency posture correction.

The problem to be solved by the present invention is not limited to the above-mentioned, another problem to be solved is not mentioned can be clearly understood by those skilled in the art from the following description. will be.

According to an embodiment of the present invention, a radio wave is radiated through an RF antenna at a radio wave transmission / reception period determined according to the timing signal by transmitting a timing signal for determining a variable navigation period and a radio wave transmission / reception period in real time to the RF transceiver. A variable timing scheduling unit to perform the control; A timing controller configured to calculate a delay time between the timing signal and the radio wave emission time of the RF antenna and determine a calculation period of the variable navigation information by reflecting the delay time; An inertial navigation information calculator configured to perform calculation of the variable navigation information in synchronization with a heartbeat generated based on the operation period; And an image processing unit which processes an image of a SAR based on the variable navigation information.

The inertial navigation information calculating unit may include an inertial navigation system, an inertial measuring unit, or any kind of signal processing unit capable of performing an inertial navigation operation, and the image processing unit may include the SAR. The two calculation units can be implemented in one system or independently.

The timing controller may include a time delay controller configured to calculate a time delay by synchronizing transmission start signals of the variable timing scheduling unit, the RF transceiver, and the RF antenna when the radio wave is radiated; And a variable timing clock for generating a variable navigation clock based on a variable operation cycle provided by the variable timing scheduling unit and a time delay value calculated by the time delay controller, and transmitting the variable timing clock to the inertial navigation information calculator and the image processor. It may include a navigation execution time control unit.

The time delay control unit may repeat a time delay operation until a first transmission start signal is input from the variable timing scheduling unit, and when the first transmission start signal is input, a second transmission start signal from the RF transceiver. The time delay operation is repeated until is input. When the third transmission start signal is input from the RF transceiver, the time delay operation is repeated until a third transmission start signal is input to the RF antenna. When the transmission start signal is input, the delay time is calculated, and the variable navigation execution time controller generates the variable timing clock based on the delay time and provides the variable timing clock to the inertial navigation information calculator and the image processor.

The timing controller may output a timing clock of the variable timing scheduling unit if the synchronization valid signal output from the variable timing scheduling unit is valid.

In addition, the timing clock may be synchronized with the heartbeat.

The variable timing clock output from the time delay controller is used as a heartbeat in the inertial navigation information calculator when the synchronization valid signal is valid, and is synchronized to a falling edge that transitions to an invalid state when the synchronization valid signal is valid. The internal timing clock of the inertial navigation information calculator may be initialized, and the internal clock may be used as the heartbeat.

According to an embodiment of the present invention, scheduling a variable radio transmission and reception period for image acquisition and transmitting it to the RF transmission and reception unit so that the radio wave is radiated through the RF antenna in the variable radio transmission and reception period and providing the variable radio transmission and reception period as a timing signal ; Calculating a delay time between the timing signal and the radio wave emission time of the RF antenna and determining a variable operation period of the variable navigation information based on the delay time; Performing operation of the variable navigation information periodically in synchronization with a heartbeat generated based on the variable operation period; And the navigation information of the inertial navigation information calculator to enable image processing based on the synchronized calculation result of the variable navigation information.

The method may include receiving an acceleration value obtained from an accelerometer in synchronization with a heartbeat of the inertial navigation information calculator; Performing error correction using a calibration value previously stored in the inertial navigation information calculator; Performing sculling compensation using a size effect for compensating rotational error and a sampling number for a variable calculation period; And performing an alignment loop having a variable operation period or calculating a variable time navigation equation based on the scalding compensation.

According to an embodiment of the present invention, an integrated design technique of SAR and an inertial navigation system and a technique for variably calculating the navigation solution of the inertial navigation system are proposed to enable time synchronization and high-frequency attitude fluctuation compensation. By synchronizing the navigation operation time of the inertial navigation system, the accuracy of SAR image synthesis can be greatly improved.

1 is a block diagram of a SAR integrated inertial navigation apparatus according to an embodiment of the present invention.
2 is a block diagram illustrating a variable time synchronization of an apparatus for providing navigation information according to an embodiment of the present invention by way of example.
3 is a flowchart illustrating a process of generating a variable timing clock with the time delay controller 4100 of FIG. 2.
4 is a waveform diagram exemplarily illustrating time synchronization and heartbeat generation between a SAR and an inertial navigation information calculator.
5 is a diagram illustrating an example of an inertial navigation information calculation unit for providing time-varying navigation information according to an embodiment of the present invention.
6 is a waveform diagram illustrating a process of acquiring inertial sensor data linked to a heartbeat of a navigation information providing apparatus according to an embodiment of the present invention.
FIG. 7 is a flowchart specifically illustrating an accelerometer error compensation process according to the variable calculation cycle of FIG. 5.
8 is a flowchart illustrating a speed compensation process according to the variable calculation cycle of FIG. 5 in detail.
FIG. 9 is a flowchart illustrating an exemplary process of selecting an accelerometer scaling method according to a variable calculation period in the sculling compensation process of FIG. 8.
FIG. 10 is a flowchart specifically illustrating a process of scaling compensation with the variable sample time of FIG. 9.
FIG. 11 is a diagram exemplarily illustrating a data reordering process for accelerometer sculling compensation.
12 is a flowchart illustrating a gyroscope error compensation process according to the variable operation period of FIG. 5 in detail.
FIG. 13 is a flowchart illustrating a process of compensating for a Corning motion error according to the variable operation period of FIG. 5.
FIG. 14 is a flowchart specifically illustrating a process for selecting a technique for compensating for a Corning motion error of FIG. 13.
FIG. 15 is a flowchart illustrating a process of compensating for a Corning motion error with the variable sample time of FIG. 14.
FIG. 16 is a flowchart specifically illustrating a variable time alignment process (closed loop) of FIG. 5.
FIG. 17 is a flowchart specifically illustrating a variable time alignment process (zero speed correction filter) of FIG. 5.
FIG. 18 is a flowchart specifically illustrating a navigation process according to a variable time of FIG. 5.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms, only the embodiments are to make the disclosure of the present invention complete, and those skilled in the art to which the present invention pertains. It is provided to fully inform the scope of the invention, and the scope of the invention is defined only by the claims.

In describing the embodiments of the present invention, detailed descriptions of well-known functions or configurations will be omitted unless they are actually necessary in describing the embodiments of the present invention. In addition, terms to be described below are terms defined in consideration of functions in the embodiments of the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the contents throughout the specification.

In the embodiment of the present invention implements the integrated design of the SAR and the inertial navigation information calculation unit to improve the image accuracy of the radar, for example, SAR having a variable radio transmission and reception period (or variable operation period), and the pulse signal transmission and reception period of the SAR In order to solve the problem of visual synchronization mismatch between the SAR and the inertial navigation information calculating unit and the high frequency attitude uncorrected problem by varying the operation periods such as the position, speed, and attitude of the navigation information in synchronization with.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention.

1 is a block diagram of a navigation system for providing navigation information to an inertial SAR according to an embodiment of the present invention.

The apparatus for providing navigation information of FIG. 1 includes a variable timing scheduling unit (1000), an RF transceiver (2000), an RF antenna unit (3000), a timing controller (4000), an inertial navigation information calculator (5000), and And an image processor [6000].

First, when the variable timing scheduling unit 1000 determines a radio wave transmission / reception period (frequency) in real time to generate a timing control signal, the radio wave transmission / reception period determined by the variable timing scheduling unit 1000 is transmitted to the RF transmission / reception unit 2000. The RF signal (radio wave) may be radiated to the atmosphere through the RF antenna unit 3000. In this process, a time delay may occur between the timing control signal (radiation output signal) of the variable timing scheduling unit 1000 and the RF signal emission time of the RF antenna unit 3000 and may serve as an image error of the SAR itself.

In addition, when the timing control signal of the variable timing scheduling unit 1000 is synchronized with the acquisition period of the inertial sensor data of the inertial navigation information calculating unit 5000, the time delay until the RF signal emission of the RF antenna unit 3000 is taken into consideration. Since navigation information is obtained without synchronization, the time synchronization between the two signals does not match. The timing control unit 4000 may compensate for the time delay element and determine the navigation operation period of the inertial navigation information calculator 5000.

The inertial navigation information calculating unit 5000 acquires inertial sensor data according to a heart beat synchronized to the variable radio wave emission command of the SAR in the timing controller 4000 and performs a navigation operation.

The image processor 6000 may provide an image in which high frequency posture fluctuation is compensated by using the navigation information of the synchronized inertial navigation information calculator 5000 and the received radio wave signal.

Existing navigation apparatus has determined the position, speed, attitude, etc. by performing a navigation operation in accordance with a fixed operation period, in the embodiment of the present invention, all navigation operations are variably synchronized to the radio wave radiation command of the SAR. The navigation information and the received RF signal of the inertial navigation information calculator [5000] output in synchronization with the variable radio wave radiation command of the SAR are transmitted to the image processor [6000] of the SAR and used for image synthesis and correction.

Transmit Start Signal outputted from the variable timing scheduling unit 1000 has a time delay generated through the RF transceiver 2000 and the RF antenna unit 3000, compared to the time point at which the radio wave radiation start signal is output. The time is delayed to radiate an RF signal through the RF antenna unit 3000.

2 is a block diagram of an apparatus for providing a variable timing clock to the inertial navigation information calculator [5000] by compensating for a variable operation period and a time delay.

The radio wave emission start signal output from the variable timing scheduling unit 1000 is transmitted to the RF transceiver 2000 after a time delay of? T ₀ hours [2001]. This signal is again passed through the RF antenna unit 3000, and after a time delay of δt ₁ , radio waves are radiated to the atmosphere [3001].

Therefore, until the radio wave radiation start signal is output from the variable timing scheduling unit 1000 and the radio wave is radiated from the RF antenna unit 3000, there may exist a delay time as shown in Equation 1 below.

The timing controller 4000 synchronizes the transmission start signals of the variable timing scheduling unit 1000, the RF transceiver 2000, and the RF antenna unit 3000 to determine a time delay until the RF antenna unit 3000 transmits a signal. Variable Navigation Execution Time Controller for receiving a variable operation cycle from the variable time delay control unit 4100 and the variable timing scheduling unit 1000 and transmitting the variable timing clock to the inertial navigation information operation unit 5000. [4500].

Data is acquired from an inertial sensor (Fig. [6]) of the inertial navigation information calculating unit [5000] in accordance with the timing of radiation of the actual waveform through the timing control unit 4000. The variable timing clock required for the variable operation of the navigation equation is variable navigation. It is transmitted to the inertial navigation information calculator [5000] through the execution time controller [4500].

The variable operation period reference value of the variable navigation execution time controller [4500] is transmitted from the variable timing scheduling unit [1000], and the time delayed by the variable timing scheduling unit (1000), the RF transceiver (2000), and the RF antenna unit (3000). The components are collected by the timing controller 4000 to determine the final variable navigation execution time.

The time delay calculation of the time delay controller 4100 and the variable timing clock generation process of the variable navigation execution time controller 4500 of FIG. 2 are described in FIG. 3.

When the time delay control function is started [4111], it repeats until the transmission start signal is input from the variable timing scheduling unit [1000] [4112]. When the transmission start signal is input, the transmission start signal is transmitted from the RF transceiver [2000]. Can be repeated until entered [4113].

When the transmission start signal is input from the RF transceiver 2000, it is repeated until the transmission start signal is input from the RF antenna unit 3000 [4114]. When the transmission start signal is input, the delay time is calculated [4115] to inertial navigation. The controller outputs the information to the information calculator [5000] and the image processor [6000] and generates a variable timing clock [4501].

The time synchronization technique between the SAR and the inertial navigation information calculator [5000] is as illustrated in FIG. 4.

In an aircraft, SAR can be operated at all times or as needed. In order to perform synchronization with the inertial navigation information calculating unit [5000], a synchronization valid signal (1002) output from the variable timing scheduling unit [1000] is provided. It is determined whether it is valid, and if it is valid, the variable timing clock 4501 may be output from the variable timing scheduling unit 1000. This signal 4501 is used as a heartbeat 5002 of the inertial navigation system, and can be synchronized with the heartbeat 5002 to acquire data from an inertial sensor gyroscope and an accelerometer.

The inertial navigation system has a periodic internal clock 5001. When the variable timing scheduler synchronization valid signal 1002 is valid, the inertial navigation information calculating unit 5000 synchronizes with the SAR variable timing clock 4501 to perform navigation operation. If the variable timing scheduler synchronization valid signal [1002] is not valid, the internal clock is initialized to a heartbeat [5002] by initializing the internal clock by synchronizing with a falling edge transitioning to an invalid state. Can be used.

The navigation information calculation method of the inertial navigation information calculation unit 5000 having a navigation operation period synchronized with the radio wave emission signal of the SAR is as illustrated in FIG. 5.

As shown in FIG. 5, when an acceleration value acquired from an accelerometer is synchronized with the heartbeat 5002 of the inertial navigation information calculating unit 5000, the error is obtained by using a calibration value previously stored in the navigation information providing apparatus. After performing the correction [5200], performing the scaling effect using a size effect that compensates the rotational error caused by the distance from the ideal origin and the number of samplings that are optimal for the variable calculation period [5300], and then performing the variable operation. An alignment loop with periods may be performed [5700] or a variable time navigation equation may be calculated [5800].

Since the operation period is variable according to the heartbeat, it is necessary to use a flexible inertial sensor sample number and operation control technique as compared to the inertial navigation information calculating unit [5000] having a periodic operation period. As in the case of the accelerometer, when a gyroscope value acquired in synchronization with the heartbeat [5002], for example, an angular acceleration is input [5400], an error correction process [5500] and a Corning motion compensation process [5600] according to a variable calculation cycle [5600] After the operation, an alignment loop having a variable operation period or a variable time navigation equation may be calculated [5800].

A variable timing diagram for data acquisition of an inertial sensor, an accelerometer and a gyroscope, is illustrated in FIG. 6.

The accelerometer value [5101] and the gyroscope value [5401] can be acquired according to the aperiodic heartbeat synchronized to the variable timing scheduling unit [1000], which is the rising or falling edge of the heartbeat. ) Or at any level.

FIG. 7 is a flowchart specifically illustrating an accelerometer error compensation process according to the variable operation period of FIG. 5.

As shown in FIG. 7, when a gravitational force obtained from an accelerometer, which is an inertial sensor, is input [5210], the specific force may be converted to a standard unit for sensor error compensation [5220].

Since the operation cycle is constantly changing, it is converted into the basic physical quantity in the unit of MKS (Meter-Kilogram-Second). For example, the sensor error is applied to the error value according to the temperature, so the temperature of the accelerometer should be properly filtered. The gain value of the filter is closely related to the time constant determined by the operation cycle, and is fixed to a constant value in a general navigation device which performs periodic operation. On the other hand, in the present invention, since the aperiodic operation is performed, the filter gain is changed according to the operation period, and it has to be calculated for each operation [5230].

When the filtering of the temperature value is completed, error correction for the accelerometer error such as bias, scale variable, and misalignment value is performed [5240]. The error factor to be corrected is determined according to the performance and output characteristics of the inertial sensor used in the inertial navigation information calculator [5000]. After the error correction of the sensor, it is converted into a time constant corresponding to the variable operation period [5250], which can be used for alignment or navigation operation.

When the accelerometer's error correction [5200] is made, the accelerometer's error component is compensated for, but the accelerometer's sculling error between the three-axis accelerometer's positional effect and navigation equation calculation It is not compensated.

8 is a flowchart illustrating a specific process for compensating for such a size effect or a sculling error for speed error compensation. When a speed increment value in which only the accelerometer itself error is compensated is input [5310], the inertial navigation information calculating unit [5000] rearranges the acquired samples for the size effect and the sculling compensation [5320]. Sufficient amount of current sample, past sample, and sample time (operation cycle) are stored in memory. The size effect caused by not placing the accelerometer at one point is compensated using the inertial sensor value and the calculation period acquired according to the variable operation period [5330]. Scaling compensation by high dynamics generated between navigation operations is performed [5340], and speed correction [5370] is performed.

Scaling compensation can be applied to various techniques corresponding to the length and length of the variable operation period.

FIG. 9 is a flowchart illustrating an example of an accelerometer sculling mode selection process according to a variable calculation period in the sculling compensation process of FIG. 8.

Scaling compensation schemes predetermine the appropriate mode according to the dynamics of the system and the calculation cycle.

When the sculling compensation process starts [5340], the operation cycle (sampling interval) at the present time is checked [5341], and the sculling technique is 1 sample 1 previous [5342], 2 samples 2 previous [5345], and 4 samples. 4 previous or [5348]. This technique is an example of compensation, and the number of samples can be arbitrarily expanded and reduced according to system characteristics. If the current operation cycle matches the previous operation cycle for all samples to be used after checking the compensation scheme [5343] [5346] [5349], it is not affected by the variable operation time, so the time constant that is currently applied is used. Sculling compensation is performed [5344] [5347] [5350].

If the current operation period does not coincide with the previous operation period, the sampling values of the past time point are interpolated to fit the current operation cycle [5351].

FIG. 10 is a flowchart specifically illustrating a process of scaling compensation with the variable sample time of FIG. 9.

First, after checking the sculling technique [5352], the calculation time required for the number of samplings selected at the current time point is calculated [5353], and the calculation time required for the number of samplings at the past time point is calculated [5354]. If the computation time (computation time constant) using sampling at the present time is greater than the computation time at the past [5355], the past sampling is extended to obtain the same amount of samples as the current computation time [5356], and if the opposite is small at present The number of past samples is divided to fit the computation time of [5357].

FIG. 11 is a diagram exemplarily illustrating a data reordering process for accelerometer sculling compensation.

11 illustrates a case of compensating sculling with 2 samples 2 previous.

The two accelerometer samples cs1 and cs2 acquired at the present time have a calculation cycle of δt ₁ and are longer than the calculation time δt ₂ and δt ₃ applied to the previous sample [5358]. In this case, several past samples are arranged in chronological order, and the past sampling data is extended to match the current computational time in accordance with the current sample time and sculling technique. Similarly, if the current operation period is shorter than the previous operation period [5339], the previous sample value is divided to match the current operation period.

FIG. 12 is a flowchart specifically illustrating a gyroscope error compensation process of FIG. 5.

First, the input angle increment value and the temperature value [5510] are converted to the standard unit (MKS) of one second unit [5520], and then, like the accelerometer, through a temperature filter having a variable gain [5530], the gyro according to the temperature The error component of the scope is compensated [5540] and converted into data having a current operation period [5550].

When the process of FIG. 12 is performed, only the error of the gyroscope sensor itself is compensated as in the case of the accelerometer.

13 is a flow chart illustrating a process for compensating for a motion error component transitioned to another axis by Corning motion.

Incremental values of angle and angular velocity with sensor error compensation [5610] rearrange the samples to fit the current compensation technique [5620] and compensate for Corning motion [5630] so that only angular or angular velocity increments remain [5660]. .

14 is a flowchart specifically illustrating a process of compensating a Corning motion error excited by a gyroscope.

The mode selection process for the Corning motion error compensation of FIG. 14 may be performed similar to the process of selecting the accelerometer sculling mode of FIG. 9.

As shown in FIG. 14, a current sampling (computation time) period check process [5631], a Corning technique check process [5632] [5635] [5638], a process of comparing the operation time of the current operation time and the previous sample [ 5633] [5636] [5639], etc., if time matches, the error can be compensated immediately without realigning the sample [5634] [5637] [5640]. If the current operation cycle does not coincide with the previous operation cycle, the sampling values of the past viewpoint may be interpolated to fit the current operation cycle [5641].

FIG. 15 is a flowchart specifically illustrating a process of interpolating the variable sample Corning motion error of FIG. 14.

The Corning motion error interpolation process of FIG. 15 has the same logical decision loop as that of the accelerometer of FIG.

As shown in FIG. 15, after checking the Corning compensation scheme (method) [5642], the calculation time required for the number of samplings selected at the present time point is calculated [5643], and the calculation time required for the number of samplings at the past time point is calculated. [5644].

If the computation time (computation time constant) using sampling at the present time is greater than the computation time at the past [5645], the past sampling is extended to secure the current computation time and the corresponding amount of samples [5646] The number of past samples can be divided to fit the computation time of the current point of time [5647].

Detailed description mechanism for explanation thereof is also specified in FIG. 11 as in the case of the accelerometer.

When the sensor error compensation and the linear velocity and the angular velocity compensation are performed, the inertial navigation information calculator 5000 enters the alignment mode 5700 or the navigation mode 5800. In general, the alignment mode [5700] may be performed first, and then the navigation mode [5800] may be entered.

The alignment and navigation of the existing inertial navigation information calculating unit is performed using a fixed arithmetic period, and no other system, for example, the SAR system and the arithmetic period (inertial sensor data sampling period) are synchronized. An embodiment of the present invention proposes a mechanism for performing alignment and navigation by acquiring data (sample) from an inertial sensor in accordance with a variable computing cycle that is constantly changing in conjunction with other systems.

16 and 17 are flowcharts illustrating the variable time alignment process of FIG. 5 in detail.

Mechanisms for performing the alignment are divided into a case of a controller using a Perup (FIG. 16) and a case of estimating and compensating a posture error of a navigation apparatus using a zero speed correction filter (FIG. 17). Even in a mechanism using a degree correction filter, a closed loop alignment technique may be used for a short time to determine an initial value of the correction filter.

First, FIG. 16 is a flowchart specifically describing the variable time alignment process (closed loop) of FIG. 5.

As shown in Fig. 16, when alignment is started [5701], an error compensated speed increment value and an angular velocity increment value are obtained [5702]. Velocity increments and angular velocity increments act as inputs to the closed loop controller, and the continuously varying operation period acts as the time constant of the closed loop to change the loop gain, so the loop gain of the closed loop is calculated for each operation [5703]. . When the loop gain is determined, the respective rotation amount is determined [5704], and the rotation amount is used to update the quaternion [5705], and the horizontal axis posture (roll, pitch) is estimated [5706]. When the alignment time reaches a preset alignment time (rough alignment time) [5707] [5708], the azimuth angle is first updated [5709]. Primary update means updating the azimuth roughly.

If the alignment method is a closed loop method [5710], the closed loop alignment is continuously performed until the alignment time reaches a preset precision alignment time. The damping gain of the closed loop can be increased or decreased to improve the attitude estimation accuracy when performing the precise alignment. When the precise alignment time reaches the completion time [5711], the azimuth angle is secondary updated (final azimuth update) and transitions to navigation mode [5714].

If the alignment scheme is not a closed loop scheme [5710], the alignment may be performed using a zero speed correction filter [5713]. The zero velocity correction filter for alignment generally uses a fixed correction period (time constant) when converting the equivalent model from the continuous time domain to the discrete time domain, but in the embodiment of the present invention, a sample is used to use a fixed correction period. We present two methods of interpolating data and using a fixed number of samples and applying a correction period value (time constant) corresponding to the number of samples when converting from a continuous time model to a discrete time model.

FIG. 17 is a flowchart specifically illustrating a variable time alignment process (zero speed correction filter) of FIG. 5.

In FIG. 17, the estimated posture values (roll, pitch, yaw) during the rough alignment may be used as initial values of the zero speed correction filter [5715]. For zero velocity correction, the navigation equation is calculated using the attitude value obtained from the coarse alignment [5716], and the position error and the speed error increase with time by the attitude error. After the navigation is performed, the following processes may be performed by determining whether the zero speed correction filter is based on a sample number [5717] or a predetermined unit time [5725].

In the case of the sample number, the navigation is accumulated until the reference number of samples is reached [5718], while the state transition matrix and the measurement matrix of the zero-speed correction filter are accumulated until the reference sample number is calculated [5719]. . Since each sample has a different operation period, the total sample time [5719] corresponding to the total number of samples [5718] may be different for each calculation. When the number of samples reaches a predetermined quantity [5720], the correction filter is discretized and calculated using the total sample time [5719] [5721]. The calculated outputs of the filters are error elements of the inertial navigation information calculating unit [5000], and the navigation equations and sensor errors may be corrected using them. In this case, the error elements of the inertial navigation information calculator 5000 may determine the order according to the required characteristics of the system. When the operation time of the zero speed correction filter reaches the preset reference time [5723], the posture correction and the error estimation through the zero speed correction filter may be stopped and the vehicle may move to the navigation mode [5724].

If the method of zero velocity correction filter is selected to be calculated based on a specific time [5725], each time a data sample is acquired from the inertial sensor, the number of samples is accumulated [5726], and the state of the correction filter and the measurement matrix Accumulate necessary variables [5727]. If the cumulative calculation time corresponding to the accumulated sample number is greater than or equal to the predetermined reference time [5728], as shown in FIG. 11, the samples are rearranged and interpolated according to the reference sample time [5729].

When the interpolation is completed, the error equation in the continuous time domain is converted into discrete time using a predetermined time as a time constant [5721]. In this case, the reference time is constant, so the discrete model can be fixed like a regular filter with a fixed time constant. After driving the alignment filter using the error equation converted into the discrete model, the navigation error, the sensor error, and the mounting error are estimated [5721], and the various errors including the calculation error of the navigation equation are corrected [5722], When the alignment time reaches the reference time [5723], it transitions to navigation mode [5723].

The transition to navigation mode can be entered automatically by an authorization command from the outside or automatically.

FIG. 18 is a flowchart illustrating a variable time navigation process of FIG. 5, for example, a process of calculating a navigation solution (position, velocity, attitude, etc.) in a navigation mode.

As shown in FIG. 18, after entering the flight mode, the navigation equation may be started using the attitude and position values [5802] calculated in the alignment mode [5801]. In this case, the heartbeat of the inertial navigation information calculating unit [5000] synchronized with the time schedule for radio wave emission of the variable timing scheduling unit [1000] can be checked [5803], and the attitude, speed, and position are updated according to the heartbeat. [5804] [5805] [5806].

The heartbeat (time constant, operation cycle) of the inertial navigation information calculation unit [5000] during the calculation of the attitude is the time constant for compensating the angular velocity due to the influence of the earth's rotation and the rotational rotation of the actual navigation device, and the calculation period for calculating the speed ( Heartbeat) It acts as a time constant such as velocity increments and Coriolis term compensation, time constants for calculation of transport rate, and position increments between calculation cycles (heartbeats) for position calculation.

As described above, according to an embodiment of the present invention, an integrated design of a SAR and an inertial navigation information calculating unit may be implemented to improve image accuracy of a radar having a variable radio wave transmission / reception period (or a variable operation period), for example, SAR. In order to implement the navigation information providing technology that can vary the operation cycle such as position, speed, attitude of navigation information by synchronizing with pulse signal transmission / reception period of SAR, fundamental visual synchronization mismatch by designing integrated SAR and inertial navigation information calculation unit And to solve the high frequency post-correction problem.

On the other hand, the combination of each block in the accompanying block diagram and each step in the flowchart may be performed by computer program instructions. These computer program instructions may be mounted on a processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, such that the instructions executed by the processor of the computer or other programmable data processing equipment are described in each block of the block diagram. It creates a means to perform the functions.

These computer program instructions may be stored on a computer usable or computer readable recording medium (or memory) or the like that can be directed to a computer or other programmable data processing equipment to implement functionality in a particular manner, thereby making the computer available. Alternatively, instructions stored on a computer readable recording medium (or memory) may produce an article of manufacture containing instruction means for performing the functions described in each block of the block diagram.

In addition, computer program instructions may be mounted on a computer or other programmable data processing equipment, such that a series of operating steps may be performed on the computer or other programmable data processing equipment to create a computer-implemented process to generate a computer or other program. Instructions that perform possible data processing equipment may also provide steps for performing the functions described in each block of the block diagram.

In addition, each block may represent a portion of a module, segment, or code that includes at least one or more executable instructions for executing a specified logical function (s). It should also be noted that in some alternative embodiments, the functions noted in the blocks may occur out of order. For example, the two blocks shown in succession may in fact be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending on the corresponding function.

1000: Variable Timing Scheduling
2000: RF Transmitter / Receiver
3000: RF antenna unit
4000: Timing Control Unit
5000: inertial navigation information calculation unit
6000: Image Processing Unit
1001: radio wave transmission signal output unit (Transmit Start Signal) of the variable timing scheduling unit
2001: RF transmission signal output unit of the RF transceiver
3001: radio wave transmission signal output unit of the RF antenna unit
4100: Time Delay Control
4500: Variable Navigation Execution Time Controller
4111: time delay control start section
4112: variable timing scheduler signal confirmation unit
4113: RF transceiver signal check unit
4114: RF antenna signal confirmation unit
4115: time delay calculation unit
4502: variable timing clock generator
4002: variable timing scheduler synchronization effective signal output unit
4501: variable timing clock output
5001: synchronized inertial navigation information calculator internal clock generator
5002 heartbeat generator
5100: accelerometer value acquisition unit
5200: Variable Time Accelerometer Error Correction
5300: Variable Time Size Effect & Scaling Compensation Unit
5400: gyroscope value acquisition unit
5500: Variable Time Gyroscope Error Correction
5600: variable time Corning motion compensation
5700 variable time alignment
5800 variable time navigation
5101: Acquire Accelerometer Values Synchronized to Heartbeat
5401: Acquire Gyroscope Values Synchronized to Heartbeat
5210: non-force input
5220: conversion unit to standard unit
5230: variable gain temperature filtering unit
5240: sensor error correction unit
5250: converting unit with a variable time period
5310: Uncompensated velocity increment input
5320: rate sampling time rearrangement
5330: size effect compensation unit
5340: Scaling Compensation Unit
5370: compensated speed increment value output
5341: sampling interval check unit
5342, 5345, 5348: Sculling Technique Identification
5343, 5346, 5349: sampling period comparison unit
5344, 5347, 5350: Scaling compensator at current sampling interval
5351: Scaling Compensator with Variable Sample Time
5352: Sculling Technique
5353: current sample total time calculation unit
5354: Total sample time calculation of the past
5355: sample time comparison unit
5356: past sample extension
5357: past sample partition
5510: angle increment value input unit
5520: standard unit conversion unit
5530: variable gain temperature filter unit
5540: sensor error correction unit
5550: variable calculation period conversion unit
5610: Uncompensated angle increment value input
5620: Reorder Sampling Times
5630: Corning Motion Compensation Unit
5660: compensated angle increment value output
5631: sampling interval check unit
5632, 5635, 5638: Corning Technique Identification
5633, 5636, 5639: sampling period comparison unit
5634, 5637, 5640: Corning compensator at current sampling interval
5641: Corning motion compensation with variable sample time
5642: Corning technique check
5643: current sample total time calculation unit
5644: total past time calculation unit
5645: sample time comparison unit
5646: past sample extension
5647: old sample partition
5701: start of alignment
5702: compensated velocity increment and angular velocity increment
5703: variable loop gain calculator
5704: angle control amount calculation unit
5705: variable time application quaternion update unit
5706: posture update unit
5707, 5708: Alignment time check unit
5709: coarse azimuth update unit
5710: alignment check unit
5711: precision alignment time check unit
5712: precision azimuth update unit
5713: Alignment section with zero speed correction filter
5714: navigation mode transition unit
5715: self-initialization with rough alignment
5716: navigation equation calculation unit
5717, 5725: Zero Speed Calibration Measurement Update Method Selection
5718: accumulation of filter state variables
5719: total sample time calculation unit
5720: sample time comparison unit
5721: Compensation filter discretization with total sample time
5722: Navigation Error Compensation
5723: alignment time check unit
5724: Navigation Mode Transition
5726: sample time count
5727: accumulation of filter state variables
5728: sample time check unit
5729: sample interpolator
5801: Navigation Equation
5802: reset posture and position
5803: Variable operation (heartbeat) new check
5804: Posture Update
5805: Speed Update
5806: location update

Claims (23)

A variable timing scheduling unit for transmitting a timing signal for determining a variable navigation period and a radio transmission / reception period to an RF transmission / reception unit to radiate radio waves through an RF antenna in a radio transmission / reception period determined according to the timing signal;
A timing controller for calculating a delay time between the timing signal and the radio wave emission time of the RF antenna and determining a calculation cycle of the variable navigation period based on the delay time;
An inertial navigation information calculator configured to periodically perform the calculation of the variable navigation period in synchronization with a heartbeat generated based on the operation period; And
And an image processor configured to process an image of a SAR based on a calculation result of the variable navigation period.
Navigation information providing device of the inertial navigation system. The method of claim 1,
The timing controller,
A time delay controller configured to calculate a time delay by synchronizing transmission start signals of the variable timing scheduling unit, the RF transceiver, and the RF antenna when the radio wave is radiated; And
And a variable navigation execution time control unit which receives a variable operation period from the variable timing scheduling unit and applies a time delay calculated by the time delay control unit to transmit a variable timing to the inertial navigation information calculation unit.
Navigation information providing device of the inertial navigation system. The method of claim 2,
The time delay control unit,
The time delay operation is repeated until a first transmission start signal is input from the variable timing scheduling unit, and when the first transmission start signal is input, the time delay until a second transmission start signal is input from the RF transceiver. The operation is repeated, and when the second transmission start signal is input from the RF transceiver, the time delay operation is repeated until a third transmission start signal is input to the RF antenna, and when the third transmission start signal is input, Calculate a delay time and provide it to the variable navigation execution time controller,
A variable timing clock is provided to the inertial navigation information calculator and the image processor.
Navigation information providing device of the inertial navigation system. The method of claim 3, wherein
The time delay control unit,
When the synchronization valid signal output from the variable timing scheduling unit is valid, the variable timing scheduling unit outputs a variable timing clock and a time delay as data or outputs a variable timing clock that compensates for the time delay.
Navigation information providing device of the inertial navigation system. The method of claim 4, wherein
The variable timing clock is synchronized with the heartbeat
Navigation information providing device of the inertial navigation system. The method of claim 4, wherein
The inertial navigation information calculation unit,
If the synchronization valid signal is not valid, it is synchronized to a falling edge that transitions to an invalid state to initialize the internal clock of the inertial navigation information calculator and set the internal clock of the inertial navigation information calculator to heartbeat. When the signal is valid, the variable timing clock is used in synchronization with the heartbeat of the navigation information calculator.
Navigation information providing device of the inertial navigation system. Transmitting, by the variable timing scheduling unit, a timing signal for determining a variable navigation period and a radio transmission / reception period to the RF transmission / reception unit so that radio waves are radiated through an RF antenna at a radio transmission / reception period determined according to the timing signal;
Calculating, by a timing controller, a delay time between the timing signal and the radio wave emission time of the RF antenna, and determining an operation period of the variable navigation period based on the delay time;
Performing an operation of the variable navigation period periodically in synchronization with a heartbeat generated based on the operation period by an inertial navigation information calculation unit; And
And an image processor processing an image of the variable navigation information synchronized based on the calculation result of the variable navigation period.
Method of providing navigation information of inertial navigation system. The method of claim 7, wherein
Receiving an acceleration value obtained from an accelerometer in synchronization with a heartbeat of the inertial navigation information calculator;
Performing error correction using a calibration value previously stored in the inertial navigation information calculator;
Performing scalding compensation using a size effect and a sampling number corresponding to a variable calculation period; And
Performing an alignment loop having a variable operation period or calculating a variable time navigation equation based on the scalding compensation;
Method of providing navigation information of inertial navigation system. The method of claim 7, wherein
Receiving an angular acceleration value obtained from a gyroscope in synchronization with a heartbeat of the inertial navigation information calculator;
Performing error correction using a calibration value previously stored in the inertial navigation information calculator;
Performing corning compensation using a sampling number for a variable calculation period; And
Performing an alignment loop having a variable operation period or calculating a variable time navigation equation based on the Corning compensation;
Method of providing navigation information of inertial navigation system. The method of claim 8,
Acquiring a sample of a gyroscope in synchronization with a variable heartbeat of the inertial navigation information calculator; And
Compensating for error and Corning motion according to the variable operation period further comprising:
Method of providing navigation information of inertial navigation system. The method of claim 10,
Acquiring a sample of the accelerometer and the gyroscope according to the heartbeat.
Method of providing navigation information of inertial navigation system. The method of claim 8,
Performing the error correction,
Receiving a specific force from the accelerometer;
Converting the specific force into standard units;
Filtering the temperature by performing a real-time calculation of a temperature filter gain that varies according to a variable calculation period of the inertial navigation information calculator;
Correcting a sensor error of the accelerometer by applying the filtering result of the temperature when the filtering of the temperature is completed; And
Converting the correction result of the sensor error into a time constant corresponding to a variable operation period.
Method of providing navigation information of inertial navigation system. The method of claim 12,
Performing the error correction,
Receiving a speed increment value according to the variable operation period; And
Compensating for the speed increment by resizing the speed increment and compensating for size effect and sculling;
Method of providing navigation information of inertial navigation system. The method of claim 8,
Rearranging the acquired samples to compensate for the scaling effect and the scalding error according to the variable operation period of the speed component compensated for only the error of the accelerometer; And
Selecting a sculling scheme in real time based on the long and short characteristics of the variable operation period;
Method of providing navigation information of inertial navigation system. The method of claim 8,
Selecting a sculling technique and a corning technique according to the large and small characteristics of the sampling number and the dynamic characteristics of the inertial navigation information calculator;
Checking a calculation period at a current time point and checking the sculling technique and the corning technique when the sculling technique and the corning technique are selected; And
Checking the computation period of the current time and the past operation time for all samples to be used after checking the sculling technique and the corning method, and interpolating past sampling values to match the operation time of the current time doing
Method of providing navigation information of inertial navigation system. The method of claim 15,
Calculating a computation time required for the number of samplings selected at the current time point after checking the sculling technique and the corning technique;
Calculating a calculation time required for the number of samplings in the past;
If the calculation time using the sampling of the current time point is greater than the calculation time of the past time point, expanding past sampling to obtain a sample equal to the current calculation time; And
Dividing the number of past samples to match the operation time of the current time when the operation time using the sampling of the current time is smaller than the operation time of the past time;
Method of providing navigation information of inertial navigation system. The method of claim 15,
When the calculation period of the accelerometer / gyroscopic sample acquired at the current time point is longer than the calculation period of the previous sample, a plurality of past samples are arranged in time order and the past sampling data is extended in accordance with the sample time and compensation technique of the current time point. Matching the operation period of the current view; And
If the operation period of the current time point is shorter than the operation period of the past time point, further comprising dividing a past sample value and matching the current operation period.
Method of providing navigation information of inertial navigation system. The method of claim 8,
Compensating an error factor of the gyroscope according to temperature through a temperature filter having a real-time variable gain after converting the input angle increment value and the temperature value into standard units; And
Further comprising converting to data having a current operation cycle
Method of providing navigation information of inertial navigation system. The method of claim 8,
Calling an error compensated speed increment value and an angular velocity increment value according to a variable operation time when the alignment is started;
Applying a variable operation period as a time constant of the closed loop in a closed loop controller for calculating a posture using the speed increment value and the angular speed increment value;
Calculating the damping gain of the closed loop at every operation;
Determining an amount of rotation corresponding to the damping gain;
Estimating a posture by updating a variable arithmetic quaternion using the respective rotation amounts;
Updating the azimuth angle when the preset coarse alignment time is reached, and continuously performing closed loop alignment while increasing, decreasing or maintaining the damping gain until the preset fine alignment time is reached if the alignment scheme is a closed loop scheme; And
If the alignment method is not the closed loop method, the method may further include performing alignment using a zero speed correction filter.
Method of providing navigation information of inertial navigation system. The method of claim 19,
Performing the alignment using the zero speed correction filter,
Using the estimated posture value as an initial value of a correction filter in the coarse alignment using the variable arithmetic time;
Calculating a navigation equation using a variable calculation period using a posture value obtained in a coarse alignment for the zero speed correction filter;
Performing the zero speed correction filter application criterion by the number of samples or a predetermined time;
Accumulating variables having different operation periods required for the state transition matrix and the measurement matrix of the zero velocity correction filter until the reference sample number is reached, based on the sample number reference;
Calculating a total sample time corresponding to the reference sample number
Discretizing the correction filter using the total sample time when the number of samples reaches a preset quantity;
Compensating navigation and sensor error using the calculated filter estimate;
If the zero speed correction filter method is selected based on a predetermined time, accumulating samples each time a data sample is acquired from an inertial sensor, and simultaneously accumulating variables necessary for a state transition matrix and a measurement matrix of the zero speed correction filter. ;
Reordering and interpolating samples according to the predetermined time criterion when a cumulative calculation time corresponding to the accumulated number of samples is greater than or equal to a predetermined reference time;
Converting an error equation of a continuous time domain into a discrete time when the interpolation is completed as a time constant;
Compensating navigation and sensor errors by estimating navigation errors, sensor errors, and mounting errors by driving alignment filters using error equations converted into discrete models; And
Transitioning to navigation mode when the alignment time reaches the reference time
Method of providing navigation information of inertial navigation system. The method of claim 7, wherein
Calculating the attitude, speed, and position of the variable navigation information by using the heartbeat as a reference time;
Method of providing navigation information of inertial navigation system. Transmitting a timing signal for determining a variable navigation period and a radio transmission and reception period to an RF transceiver so that radio waves are radiated through an RF antenna at a radio transmission and reception period determined according to the timing signal;
Calculating a delay time between the timing signal and the radio wave emission time of the RF antenna and determining an operation period of the variable navigation period based on the delay time;
Performing operations of the variable navigation period periodically in synchronization with a heartbeat generated based on the operation period; And
A program including an instruction for performing an operation of processing the image of the variable navigation information synchronized based on the operation result of the variable navigation period;
Computer-readable recording media. Transmitting a timing signal for determining a variable navigation period and a radio transmission and reception period to an RF transceiver so that radio waves are radiated through an RF antenna at a radio transmission and reception period determined according to the timing signal;
Calculating a delay time between the timing signal and the radio wave emission time of the RF antenna and determining an operation period of the variable navigation period based on the delay time;
Performing operations of the variable navigation period periodically in synchronization with a heartbeat generated based on the operation period; And
Processing the image of the variable navigation information synchronized based on the operation result of the variable navigation period;
Computer program stored on a computer readable recording medium.

Images