JP2012103023A - Apparatus and method for correcting angular velocity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique improving derivation accuracy of an angular velocity even in a short period.SOLUTION: A measuring part 10 obtains positioning data of an object measured based on a signal from a GPS satellite and an angular velocity of the object which has been output by an angular velocity sensor 26. An off-set value computing part 28 estimates a traveling state of the object based on the positioning data and the angular velocity. The off-set value computing part 28 sequentially derives temporary off-set values while changing a combination of the positioning data and the angular velocity corresponding to the estimated traveling state of the object, and then executes statistical processing to the temporary off-set values, thereby deriving an off-set value. A sensitivity coefficient computing part 30 sequentially derives temporary sensitivity coefficients based on the positioning data and the angular velocity, and then executes statistical processing to the temporary sensitivity coefficients, thereby deriving a sensitivity coefficient. An angular velocity converting part 14 derives a final angular velocity based on the sensitivity coefficient, the off-set value, and the angular velocity.

Description

  The present invention relates to an angular velocity sensor correction technique, and more particularly to an angular velocity sensor correction apparatus and an angular velocity sensor correction method for deriving a value for correcting an output signal from an angular velocity sensor.

In a vehicular navigation apparatus, generally, an optimum position is estimated by combining a position calculated from a self-contained navigation and a position calculated from a GPS (Global Positioning System). In the self-contained navigation, the current position is calculated by updating the previous positioning position based on the speed pulse indicating the speed of the vehicle and the turning angular speed of the vehicle measured by the angular speed sensor. According to such a type of navigation device, the position of the vehicle can be derived by self-contained navigation even in tunnels, underground parking lots and valleys of high-rise buildings where it is difficult to receive radio waves from GPS satellites. The angular velocity ω due to turning of the vehicle is derived by the following equation.
ω = (Vout−Voffset) / S (1)
Here, Vout is an output voltage of the angular velocity sensor, Voffset is an offset value of the angular velocity sensor, and S (mV / deg / sec) is a sensitivity coefficient of the angular velocity sensor.

  In order to accurately determine the angular velocity, it is necessary to accurately determine the offset value of the angular velocity sensor and the sensitivity coefficient. The sensitivity coefficient of the angular velocity sensor generally differs depending on the individual difference of the angular velocity sensor and the mounting angle of the angular velocity sensor to the vehicle. In addition, the offset value may change due to a temperature change. In other words, the offset value is affected by temperature rise due to heat generated by the substrate used in the vehicle navigation device or heat generated by the vehicle engine when the vehicle navigation device is attached to the dashboard of the vehicle. Conventionally, the offset value of the angular velocity sensor has been corrected by using the output voltage from the angular velocity sensor when the vehicle is stopped or is traveling straight ahead when the angular velocity is “0”. However, it is difficult to periodically correct the offset value of the angular velocity sensor in cases where the frequency of stoppage of the vehicle is low, such as traveling on a highway or traveling for a long time in an area with low traffic volume. Is likely to get worse. The offset value correction during straight running so that the output voltage from the angular velocity sensor accurately becomes “0” is also easily influenced by the road shape and the driving situation of the driver, and thus it is difficult to perform it periodically. The sensitivity coefficient of the angular velocity sensor is derived from the azimuth change amount within the unit period and the output voltage of the angular velocity sensor. Therefore, as is apparent from the equation (1), the sensitivity coefficient of the angular velocity sensor is affected by the error of the offset value.

There has been proposed a technique for correcting an offset and a sensitivity coefficient of an angular velocity sensor even during traveling other than straight traveling. There, the offset value and sensitivity coefficient of the angular velocity sensor are corrected based on the average value of the output voltage of the angular velocity sensor during a predetermined period and the amount of change in the direction of the vehicle during the period during which the average value is calculated. More specifically, the offset value Voffset of the angular velocity sensor is derived as follows.
Voffset = 1 / n · ΣVout−1 / Δt · Δθ / n · S (2)
Here, n is the number of samples of the output voltage of the angular velocity sensor, Δt (sec) is the sampling interval, and Δθ (deg) is the azimuth change amount. The azimuth change amount is obtained based on the GPS azimuth obtained from the GPS satellite or map data. Further, the sensitivity coefficient of the angular velocity sensor is derived as follows when the amount of change in the corrected offset value is small, that is, in a stable state.
S = (1 / n · ΣVout−Voffset) · n / Δθ · Δt (3)
Here, Voffset is known and is a constant in a stable state where the amount of change in the corrected offset value is small (for example, Patent Document 1).

JP 2001-330454 A

  Under such circumstances, when the number of samples is increased by the fact that Voffset in Equation (3) is not stable until a stable state in which the amount of change in the offset value is small with respect to the sensitivity coefficient of the angular velocity sensor, The sensitivity coefficient error may increase. In general, it takes a period of 30 minutes to 1 hour or more from the time of startup until the offset value is stabilized. For this reason, for example, when traveling for about 30 minutes or less, it is very difficult to accurately correct the sensitivity coefficient of the angular velocity sensor, and the accuracy of deriving the angular velocity is not high. In order to improve the accuracy of deriving the angular velocity in a short period after startup, it is required to derive the offset value of the angular velocity sensor with high accuracy in a short period.

  Further, in the equation (3) for deriving the sensitivity coefficient of the angular velocity sensor, when the azimuth change amount Δθ is obtained from the GPS azimuth obtained from the GPS satellite, the accuracy of the GPS azimuth depends on the reception status of the radio wave from the GPS satellite. Since it deteriorates, the error included in the sensitivity coefficient increases. In addition, in the equation (3), when the direction change amount Δθ is obtained based on the map data, the road direction based on the map data and the traveling direction of the vehicle do not always coincide with each other, and thus are included in the sensitivity coefficient. The error increases. Even in these cases, it is required to reduce the error included in the sensitivity coefficient.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a technique for improving the accuracy of deriving angular velocity even in a short period.

  In order to solve the above problems, an angular velocity sensor correction device according to an aspect of the present invention includes positioning data of an object measured based on a signal from a GPS satellite, and an angular velocity of the object output from the angular velocity sensor. , An offset value deriving unit that sequentially derives a temporary offset value of the angular velocity sensor by using at least the angular velocity acquired by the acquiring unit, and a temporary value of the angular velocity sensor that is sequentially derived by the offset value deriving unit An offset value filter processing unit that derives an offset value of the angular velocity sensor for correcting the angular velocity output from the angular velocity sensor by executing statistical processing on the offset value. The offset value filter processing unit derives the first azimuth change amount based on the positioning data acquired by the acquisition unit, and the second value based on the temporary offset value of the angular velocity sensor derived by the offset value derivation unit. An azimuth change amount derivation unit for deriving an azimuth change amount, a difference change amount derivation unit for deriving a change amount of a difference between the first azimuth change amount and the second azimuth change amount derived by the azimuth change amount derivation unit; An adjustment unit that adjusts the forgetting factor in the statistical process based on the change amount of the difference derived by the difference change amount deriving unit.

  According to this aspect, the forgetting factor is based on the change amount of the difference between the first azimuth change amount derived based on the positioning data and the second azimuth change amount derived based on the temporary offset value. Therefore, a forgetting factor suitable for the current temporary offset value can be set.

  The adjustment unit derives the offset value of the angular velocity sensor as the change amount of the absolute value of the change amount of the difference derived by the difference change amount deriving unit increases or when the absolute value change amount of the difference change amount exceeds a predetermined value. The forgetting factor may be adjusted so that the influence of the newly derived temporary offset value becomes large. In this case, since the forgetting factor is set such that the influence of the newly derived temporary offset value increases as the absolute value change amount of the difference change amount increases, the actual fluctuation of the offset value can be followed.

  You may further provide the estimation part which estimates the traveling state of a target object based on the positioning data and angular velocity which were acquired in the acquisition part. The offset value deriving unit uses the combination of the positioning data acquired by the acquisition unit and the angular velocity when the estimation unit estimates the non-straight running state as the traveling state of the object, thereby providing a temporary offset value of the angular velocity sensor. And the adjusting unit may adjust the forgetting factor when the estimating unit estimates the non-straight running state as the running state of the object. In this case, since the adjustment of the forgetting factor is executed in the non-straight running state, the forgetting factor can be finely adjusted when the offset value tends to shift.

  The offset value deriving unit sequentially derives the temporary offset value of the angular velocity sensor by using the angular velocity acquired in the acquiring unit when the estimating unit estimates the straight traveling state as the traveling state of the object, and the adjusting unit In the case where the estimation unit estimates the straight traveling state as the traveling state of the object, the forgetting factor is adjusted, and the straight traveling state is more than the adjustment range of the forgetting factor in the non-straight traveling state. The adjustment range of the forgetting factor may be increased. In this case, since the adjustment range of the forgetting factor in the case of the straight traveling state is made larger than the adjustment range of the forgetting factor in the case of the non-straight running state, it is possible to follow the actual fluctuation of the offset value.

  Another aspect of the present invention is an angular velocity sensor correction method. In this method, at least using the positioning data of the object measured based on the signal from the GPS satellite and the angular velocity of the object output from the angular velocity sensor, and using the acquired angular velocity, A step of sequentially deriving a temporary offset value of the angular velocity sensor, and executing statistical processing on the temporarily derived temporary offset value of the angular velocity sensor, thereby correcting an angular velocity output from the angular velocity sensor. Deriving an offset value. In the step of deriving the offset value of the angular velocity sensor, the first azimuth change amount is derived based on the obtained positioning data, and the second azimuth variation amount is calculated based on the derived temporary offset value of the angular velocity sensor. A deriving step, a step of deriving a change amount of the difference between the derived first azimuth change amount and the second azimuth change amount, and a forgetting factor in statistical processing based on the derived change amount of the difference Adjusting.

  The adjustment step is a new derivation in the offset value derivation of the angular velocity sensor when the absolute value change amount of the derived difference change amount becomes larger or when the absolute value change amount of the difference change exceeds a predetermined value. The forgetting factor may be adjusted so that the influence of the provisional offset value becomes large.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as an aspect of the present invention.

  According to the present invention, the accuracy of deriving angular velocity can be improved even in a short period.

It is a figure which shows the structure of the angular velocity calculation apparatus which concerns on the Example of this invention. It is a figure which shows the structure of the offset value calculating part of FIG. It is a figure which shows the structure of the offset value filter process part of FIG. It is a figure which shows the data structure of the table memorize | stored in the forgetting factor setting part of FIG. It is a figure which shows the structure of the forgetting factor control part of FIG. It is a figure which shows the structure of the sensitivity coefficient calculating part of FIG. It is a figure which shows the data structure of the table memorize | stored in the sensitivity coefficient filter part of FIG. It is a flowchart which shows the derivation | leading-out procedure of the offset value by the angular velocity calculation apparatus of FIG. It is a flowchart which shows the derivation | leading-out procedure of the forgetting factor (alpha) 2 by the angular velocity calculation apparatus of FIG. It is a flowchart which shows the derivation | leading-out procedure of the sensitivity coefficient by the angular velocity calculation apparatus of FIG.

  Before describing the present invention specifically, an outline will be given first. An embodiment of the present invention relates to an angular velocity calculation device that is mounted on a vehicle or the like and derives an angular velocity due to turning of the vehicle. The angular velocity calculation device derives an angular velocity for the output voltage from the angular velocity sensor while using the offset value and the sensitivity coefficient. As described above, the offset of the angular velocity sensor is affected by temperature fluctuations. In addition, an error in the offset value affects the accuracy of calculating the sensitivity coefficient. As a result, in such a state, the accuracy of the angular velocity is deteriorated. In order to cope with this, the angular velocity calculation apparatus according to the present embodiment executes the following processing.

  The angular velocity calculation device inputs an output voltage from an angular velocity sensor mounted on the vehicle and inputs positioning data from a GPS receiver mounted on the vehicle. Here, the output voltage from the angular velocity sensor corresponds to the angular velocity of the vehicle. Further, the positioning data includes a vehicle direction, a vehicle speed, a vehicle altitude, and the like. The angular velocity calculation device estimates the traveling state of the vehicle based on the positioning data and the output voltage. As the traveling state, for example, any one of a stopped state, a straight traveling state, and a non-straight traveling state is specified. Further, the angular velocity calculating device sequentially derives a temporary offset value by a deriving method according to the traveling state. Furthermore, the angular velocity calculation device performs a filter process on the temporary offset value derived sequentially. Here, the filter corresponds to a low-pass filter.

  Further, the forgetting factor set in the filter is determined according to the traveling state. For example, since the accuracy of the temporary offset value is high in the stop state or the straight traveling state, a forgetting factor that reduces the influence of the past value is set. On the other hand, since the accuracy of the temporary offset value is low in the non-straight running state, a forgetting factor that increases the influence of the past value is set. The output value of the filter corresponds to the offset value. The angular velocity calculation device sequentially derives a temporary sensitivity coefficient based on the positioning data and the output voltage. In addition, the angular velocity calculation device performs a filtering process on the temporary sensitivity coefficient that is sequentially derived, as in the case of the offset value. The output value of the filter corresponds to the sensitivity coefficient. Finally, the angular velocity calculation device calculates the angular velocity based on the output voltage from the angular velocity sensor, the offset value, and the sensitivity coefficient.

  In such a configuration, it is desirable if the accuracy of deriving the angular velocity can be improved even under the following circumstances. When the running state is non-straight running, if the influence of past offset values is large, it may take time to follow the true offset value. For example, when the air conditioner is turned ON / OFF in the vehicle, the temperature of the dashboard changes abruptly, and accordingly, the offset value also changes greatly. At this time, if the forgetting factor is set so as to increase the influence of the past offset value, the derived offset value includes an error in the period until the true offset value is followed. Further, when an error is included in the offset value, the derived sensitivity coefficient also includes an error. In order to improve the accuracy of deriving the angular velocity even in a situation where the ambient temperature varies greatly during non-straight running, it is required to derive the offset value of the angular velocity sensor with high accuracy in a short period of time.

  In order to cope with this, the angular velocity calculation apparatus according to the present embodiment, in the case of a non-straight running state, determines the amount of change from the past with respect to the difference value between the azimuth change calculated from the angular velocity sensor and the azimuth change calculated from GPS. The absolute value is derived. In addition, the angular velocity calculation device derives the change amount of the absolute value in a certain period, and changes the forgetting factor for deriving the offset value based on the change amount of the absolute value. For example, if the change amount of the absolute value is equal to or greater than a predetermined value, the forgetting factor is changed so that the weight of the current temporary offset value is increased, and the followability to the change of the offset value is improved. On the other hand, if the change amount of the absolute value is smaller than the predetermined value, the forgetting factor is changed so that the weight of the current temporary offset value is reduced, and the stability when the change of the offset value is small is improved. The forgetting factor for deriving the sensitivity coefficient is changed according to the forgetting factor for deriving the offset value. For example, when the temperature fluctuation is small and the offset value drift is small, the accuracy of deriving the offset value is high and the error is small. Therefore, a forgetting factor that reduces the influence of the past value is set. On the other hand, when the temperature variation is large and there is an offset drift, a forgetting factor that increases the influence of the past value is set.

  FIG. 1 shows a configuration of an angular velocity calculating apparatus 100 according to an embodiment of the present invention. The angular velocity calculation device 100 includes a measurement unit 10, a parameter calculation unit 12, an angular velocity conversion unit 14, and a control unit 34. The measurement unit 10 includes a GPS positioning unit 20, an effectiveness determination unit 22, an inclination detection unit 24, and an angular velocity sensor 26. The parameter calculation unit 12 includes an offset value calculation unit 28, a sensitivity coefficient calculation unit 30, and positioning data storage. Part 32 is included. Further, GPS positioning data 200, output signal 202, tilt angle 204, offset value 206, sensitivity coefficient 208, and storage data 210 are included as signals.

  The GPS positioning unit 20 receives a signal from a GPS satellite (not shown) and calculates GPS positioning data 200. The GPS positioning data 200 includes the longitude and latitude, the GPS altitude that is the altitude of the vehicle, the GPS speed that is the moving speed, the GPS direction that is the direction of the vehicle, the PDOP (Position Division Precision), the number of captured satellites, and the like. Here, PDOP is an index of how the error of the GPS satellite position in the GPS positioning data 200 is reflected in the reception point position, and corresponds to the positioning error. Note that the GPS positioning data 200 may include values other than these. Further, since the GPS positioning data 200 may be calculated by a known technique, description thereof is omitted here. The GPS positioning unit 20 calculates the GPS positioning data 200 at every sampling interval, that is, periodically. The GPS positioning unit 20 sequentially outputs the GPS positioning data 200 to the validity determination unit 22.

  The validity determination unit 22 sequentially inputs the GPS positioning data 200 from the GPS positioning unit 20. The validity determination unit 22 determines the validity of each GPS positioning data 200 from the GPS positioning data 200. For example, when the value of PDOP is equal to or less than a first threshold value and the GPS speed is equal to or greater than a second threshold value, the validity determination unit 22 determines that the GPS direction corresponding to them is valid. judge. The validity determination unit 22 determines that the corresponding GPS azimuth is invalid when the above condition is not satisfied. This is because the accuracy of the GPS orientation tends to be low when the PDOP value is large or the GPS speed is low. More specifically, when the value of PDOP is 6 or less and the GPS speed is 20 km / h or more, the validity determination unit 22 represents the validity of the GPS direction with a flag.

  Moreover, the effectiveness determination part 22 determines with the said GPS speed being effective, when a GPS speed is more than a 3rd threshold value. Here, the third threshold value may be the same as the second threshold value. Further, the validity determination unit 22 determines that the GPS altitude is valid when the difference in GPS altitude in the predetermined period is equal to or smaller than the fourth threshold value. As a result of such processing, the validity determination unit 22 adds a flag indicating validity or invalidity to each value such as GPS azimuth included in the GPS positioning data 200 (hereinafter, a flag is added). GPS positioning data 200 is also referred to as “GPS positioning data 200”). The validity determination unit 22 sequentially outputs the GPS positioning data 200 to the inclination detection unit 24, the offset value calculation unit 28, the sensitivity coefficient calculation unit 30, and the positioning data storage unit 32.

  The inclination detection unit 24 sequentially inputs GPS positioning data 200 from the validity determination unit 22, particularly the GPS altitude included in the GPS positioning data 200. The inclination detection unit 24 detects an average inclination angle of the vehicle at a sampling interval (hereinafter referred to as “inclination angle 204”) based on the GPS altitude that is sequentially input. More specifically, the inclination detection unit 24 calculates the difference between successive GPS altitudes, averages the calculation results, and then divides the average value by the sampling interval to derive the inclination angle 204. Here, the interval between successive GPS altitudes corresponds to the sampling interval. The tilt detection unit 24 outputs the tilt angle 204 to the offset value calculation unit 28, the sensitivity coefficient calculation unit 30, and the positioning data storage unit 32.

  The angular velocity sensor 26 corresponds to, for example, a gyro apparatus such as a vibration gyro, and detects a change in the traveling direction of the vehicle as a relative angular change of the vehicle. That is, the angular velocity sensor 26 detects the turning angular velocity of the vehicle. The detected angular velocity is output as an analog signal of 0V to 5V, for example. At that time, the positive angular velocity corresponding to the clockwise turn is output as a deviation voltage from 2.5V toward 5V, and the negative angular velocity corresponding to the counterclockwise turn is from 2.5V toward 0V. Output as deviation voltage. Further, 2.5V is an offset value of the angular velocity, that is, a zero point, and drifts under the influence of temperature and the like.

  The sensitivity coefficient (mV / deg / sec), which is about the deviation of angular velocity from 2.5V, is determined as a predetermined value that falls within the allowable error in a horizontal state. The cause of this allowable error is the individual difference of the gyro device, the secular change, the influence of temperature, and the like. The voltage value of the gyro device is AD converted by an AD (Analog to Digital) converter (not shown), for example, at a sampling interval of 100 msec, and the resulting digital signal is output. The digital signal corresponds to the aforementioned output voltage, and hereinafter, the term output signal 202 is used. In addition, since a well-known technique should just be used as a gyro apparatus, description is abbreviate | omitted here. The angular velocity sensor 26 outputs an output signal 202 to the offset value calculation unit 28, the sensitivity coefficient calculation unit 30, the positioning data storage unit 32, and the angular velocity conversion unit 14.

  The offset value calculation unit 28 receives the GPS positioning data 200 from the validity determination unit 22, the tilt angle 204 from the tilt detection unit 24, and the output signal 202 from the angular velocity sensor 26. The offset value calculator 28 also receives the sensitivity coefficient 208 from the sensitivity coefficient calculator 30. The offset value calculation unit 28 sequentially updates the offset value (hereinafter referred to as “offset value 206”) of the angular velocity sensor 26 based on the GPS positioning data 200, the output signal 202, the tilt angle 204, and the sensitivity coefficient 208. calculate. Details of processing in the offset value calculation unit 28 will be described later. The offset value calculation unit 28 outputs the offset value 206 to the angular velocity conversion unit 14.

  The sensitivity coefficient calculation unit 30 receives the GPS positioning data 200 from the validity determination unit 22, the tilt angle 204 from the tilt detection unit 24, and the output signal 202 from the angular velocity sensor 26. The sensitivity coefficient calculation unit 30 also receives the offset value 206 from the offset value calculation unit 28. The sensitivity coefficient calculation unit 30 calculates the sensitivity coefficient of the angular velocity sensor 26 (hereinafter referred to as “sensitivity coefficient 208” described above) based on the GPS positioning data 200, the output signal 202, the tilt angle 204, and the offset value 206. . Details of the processing in the sensitivity coefficient calculation unit 30 will be described later. The sensitivity coefficient calculation unit 30 outputs the sensitivity coefficient 208 to the angular velocity conversion unit 14.

  The positioning data storage unit 32 includes a ring buffer or the like on a memory, and sequentially receives the GPS positioning data 200 from the validity determination unit 22, the tilt angle 204 from the tilt detection unit 24, and the output signal 202 from the angular velocity sensor 26. To do. The positioning data accumulating unit 32 acquires the GPS positioning data 200 determined to be valid by the validity determining unit 22, and a predetermined period before the period when the offset value calculating unit 28 derives a temporary offset value 212 described later, for example, If it is valid for 10 seconds continuously, the GPS positioning data 200, the tilt angle 204, and the output signal 202 are stored as the storage data 210. The stored data 210 is updated every time valid GPS positioning data is input. The positioning data storage unit 32 does not update the stored data 210 when the input GPS positioning data 200 is invalid. In addition, when it is invalid for a predetermined period, for example, 60 seconds, the stored data 210 is cleared. The positioning data storage unit 32 outputs the stored storage data 210 to the offset value calculation unit 28.

  The angular velocity conversion unit 14 inputs an output signal 202 from the angular velocity sensor 26, an offset value 206 from the offset value calculation unit 28, and a sensitivity coefficient 208 from the sensitivity coefficient calculation unit 30. The angular velocity conversion unit 14 calculates the angular velocity ω of the vehicle by calculating the above equation (1) based on the output signal 202, the offset value 206, and the sensitivity coefficient 208. The angular velocity conversion unit 14 outputs an angular velocity ω. The control unit 34 controls the overall operation of the angular velocity calculation device 100.

  This configuration can be realized in terms of hardware by a CPU, memory, or other LSI of any computer, and in terms of software, it can be realized by a program loaded in the memory, but here it is realized by their cooperation. Draw functional blocks. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  FIG. 2 shows a configuration of the offset value calculation unit 28. The offset value calculation unit 28 includes a state estimation unit 40, a state-specific offset value derivation unit 42, and an offset value filter processing unit 44. The state estimation unit 40 includes a stop estimation unit 50, a straight travel estimation unit 52, and a non-straight travel estimation unit 54. The state-specific offset value deriving unit 42 includes a stop offset value deriving unit 56, and a straight travel offset value. A deriving unit 58 and an offset value deriving unit 60 during non-straight running are included. Further, a temporary offset value 212 and traveling state information 214 are included as signals.

  The state estimation unit 40 receives the GPS positioning data 200, the output signal 202, and the tilt angle 204. The state estimation unit 40 estimates the traveling state of the vehicle in the stop estimation unit 50, the straight travel estimation unit 52, and the non-straight travel estimation unit 54. Here, as the running state of the vehicle, it is estimated whether the vehicle is in a stopped state or going straight, or the remaining state, that is, a non-straight running state. Further, the state estimation unit 40 outputs the determination result as the traveling state information 214 to the offset value filter processing unit 44.

  The stop estimation unit 50 acquires the GPS positioning data 200 determined to be effective by the effectiveness determination unit 22 (not shown). Further, the stop estimation unit 50 extracts the GPS speed from the GPS positioning data 200, and confirms whether the GPS speed is “0”. On the other hand, the stop estimation unit 50 calculates a variance value of the output signal 202 within a predetermined period, and compares the variance value with a fifth threshold value. The stop estimation unit 50 determines that the vehicle is in a stopped state when the GPS speed is 0 and the variance value is smaller than the fifth threshold value. As described above, when the GPS speed is low, the accuracy tends to be low. However, the stop estimation unit 50 determines that the stop has occurred by using the variance value of the output signal 202 together. Here, the predetermined period is, for example, 1 sec which is a sampling interval of the GPS speed. When the variance value of the output signal 202 is small during the predetermined period, it is estimated that the vehicle is in a stable state without shaking or the like. If the stop estimating unit 50 determines that the vehicle is not in the stopped state, the stop estimating unit 50 outputs the fact to the non-straight running estimation unit 54.

  The straight traveling estimation unit 52 acquires the GPS positioning data 200 determined to be effective by the effectiveness determination unit 22 (not shown). Further, the straight traveling estimation unit 52 extracts a GPS azimuth from the GPS positioning data 200 and derives a change in the GPS azimuth over a predetermined period (hereinafter referred to as “GPS azimuth change”). Further, the straight traveling estimation unit 52 confirms whether the GPS azimuth change is “0”. The straight traveling estimation unit 52 calculates a variance value of the output signal 202 in a predetermined period, and compares the variance value with a sixth threshold value. Note that the sixth threshold value may be the same as the fifth threshold value. Here, the predetermined period is set to a period in which the GPS azimuth change is continuously zero, for example.

  The straight traveling estimation unit 52 determines that the vehicle is traveling straight when the GPS azimuth change is 0 and the variance value is smaller than the sixth threshold value. If the variance value of the output signal 202 is small during the predetermined period, it is estimated that the vehicle is traveling straight without being affected by subtle meandering. Depending on the driver's driving situation and road shape, for example, in an urban area or the like, the detection frequency of the straight traveling state is generally lower than the determination of the stop state by the stop estimation unit 50, and the period is about several seconds. is there. When the straight traveling estimation unit 52 determines that the vehicle is not in the straight traveling state, the straight traveling estimation unit 52 outputs the fact to the non-straight traveling estimation unit 54. Here, when the stop estimation unit 50 determines that the vehicle is in the stopped state, and the straight traveling traveling estimation unit 52 determines that the vehicle is in the straight traveling state, the determination result of the stop estimating unit 50 is given priority. When the non-straight running estimation unit 54 inputs from the stop estimating unit 50 that the vehicle is not in a stopped state and from the straight running estimation unit 52, the vehicle is in a non-straight running state. Is determined.

  The state-specific offset value deriving unit 42 receives the GPS positioning data 200, the output signal 202, the tilt angle 204, and the sensitivity coefficient 208. The state-specific offset value deriving unit 42 sequentially derives the temporary offset value 212 of the angular velocity sensor 26 according to the traveling state of the vehicle estimated by the state estimating unit 40. When the stop estimation unit 50 determines that the vehicle is stopped, the stop offset value deriving unit 56 sequentially derives the temporary offset value 212 based on the output signal 202. When the straight travel estimation unit 52 determines that the vehicle is traveling straight, the straight travel offset value deriving unit 58 sequentially derives the temporary offset value 212 based on the output signal 202.

  Further, when it is determined in the straight travel offset value deriving unit 58 that the non-straight travel state is determined, the non-straight travel offset value deriving unit 60 uses the GPS positioning data 200, the output signal 202, the inclination angle 204, and the sensitivity coefficient 208. The temporary offset value 212 is sequentially derived. That is, the offset value deriving unit 60 during non-straight traveling from the stop offset value deriving unit 56 derives the temporary offset value 212 while changing the combination of the GPS positioning data 200, the output signal 202, and the like according to the traveling state of the vehicle. To do.

  The stop-time offset value deriving unit 56 sequentially derives the temporary offset value 212 of the angular velocity sensor 26 based on the output signal 202 when it is determined that the vehicle is stopped. Specifically, the offset value deriving unit 56 at the time of stop uses the fact that the turning angular velocity of the vehicle becomes “0” at the time of stop, and calculates the average value of the output signal 202 as the temporary offset value 212. The straight traveling offset value deriving unit 58 sequentially derives the temporary offset value 212 of the angular velocity sensor 26 based on the output signal 202 when it is determined that the vehicle is traveling straight. Specifically, since the turning angular velocity of the vehicle is also 0 here, the straight traveling offset value deriving unit 58 calculates the average value of the output signal 202 as the temporary offset value 212.

When it is determined that the vehicle is in a non-straight running state, the offset value deriving unit 60 during non-straight running is based on the GPS heading, inclination angle 204, output signal 202, and sensitivity coefficient 208 in the GPS positioning data 200. For example, the temporary offset value 212 at the GPS azimuth sampling interval is sequentially derived. Here, the temporary offset value 212 is derived as follows.
Goffset = 1 / n · ΣGout−Δθ · Gsensitivity · cos (α) (4)
Here, n is the number of samples of the output signal 202 at the GPS azimuth sampling interval, and ΣGout (mV) is the total value of the output signal 202 at the GPS azimuth sampling interval. Further, Δθ (deg) is a GPS azimuth change amount, Gsensitivity (mV / deg / sec) is a sensitivity coefficient 208, and α (deg) is a vehicle inclination angle 204.

  The sensitivity coefficient 208 is normally input from the sensitivity coefficient calculation unit 30 (not shown), but the sensitivity coefficient 208 may not be calculated yet in a state such as immediately after activation of the angular velocity calculation apparatus 100. In such a case, the offset value deriving unit 60 during non-straight running uses the sensitivity coefficient 208 determined by the specifications of a gyro device (not shown) as an initial value. Further, the offset value deriving unit 60 during non-straight running may store the sensitivity coefficient 208 from the sensitivity coefficient calculation unit 30 at the end of the previous run and use it as an initial value.

  The offset value filter processing unit 44 inputs the temporary offset value 212 sequentially derived by the state-specific offset value deriving unit 42. The offset value filter processing unit 44 derives the offset value 206 of the angular velocity sensor 26 by performing statistical processing on the temporary offset value 212. Hereinafter, the processing in the offset value filter processing unit 44 will be described with reference to FIG.

  FIG. 3 shows a configuration of the offset value filter processing unit 44. The offset value filter processing unit 44 includes an αi multiplication unit 70, an addition unit 72, a 1-αi multiplication unit 74, a forgetting factor setting unit 76, and a forgetting factor control unit 78. As illustrated, the offset value filter processing unit 44 is configured to include an IIR (Infinite Impulse Response) filter, and the IIR filter configures a low-pass filter. The αi multiplier 70 multiplies the temporary offset value 212 by the forgetting factor “αi”. Here, “i” is 1 or 2. Therefore, the forgetting factor “αi” is a general term for α1 and α2. Α1 and α2 will be described later. The αi multiplier 70 outputs the multiplication result to the adder 72.

  The adder 72 sequentially adds the multiplication result from the αi multiplier 70 and the multiplication result from the 1-αi multiplier 74. The adder 72 sequentially outputs the addition result as an offset value 206. The 1-αi multiplier 74 multiplies the offset value 206 by a coefficient “1-αi”. Note that “αi” in the coefficient “1-αi” is the same as αi in the αi multiplier 70, and thus the description thereof is omitted here. The 1-αi multiplier 74 feeds back the multiplication result to the adder 72. The forgetting factor setting unit 76 inputs the running state information 214. Further, the forgetting factor setting unit 76 determines the value of the forgetting factor “αi” according to the state indicated by the traveling state information 214. Further, the forgetting factor setting unit 76 sets the determined forgetting factor “αi” in the αi multiplication unit 70 and the 1-αi multiplication unit 74.

  FIG. 4 shows the data structure of the table stored in the forgetting factor setting unit 76. As shown, a running state column 300 and a forgetting factor column 302 are included. The traveling state column 300 includes each state indicated by the traveling state information 214. The forgetting factor column 302 stores a forgetting factor “αi” corresponding to each state. That is, the forgetting factor “α1” is associated with the stop state and the straight traveling state, and the forgetting factor “α2” is associated with the non-straight traveling state. Here, α2 <α1 is defined. Α1 is a fixed value, while α2 is a variable value. Returning to FIG. Forgetting factor control unit 78 determines the value of forgetting factor “α2” based on sensitivity factor 208 and stored data 210, and outputs the determined value of forgetting factor “α2” to forgetting factor setting unit 76.

Here, the reason for changing the forgetting factor will be described. Due to the configuration of the offset value filter processing unit 44, the offset value 206Voffset (t) at time t is expressed as follows.
Voffset (t) = αiGoffset (t) + (1−αi) Voffset (t−1) (5)
Goffset (t) is the temporary offset value 212 at time t. That is, when αi increases, the influence of Goffset (t) in Voffset (t) increases, and when αi decreases, the influence of Voffset (t−1) in Voffset (t) increases. This corresponds to an increase in the influence of the new temporary offset value 212 in the former case and an increase in the influence of the past offset value 206 in the latter case.

  For example, in the stop state or the straight traveling state, the temporary offset value 212 is derived from the output signal 202 in a state where the turning angular velocity of the vehicle is 0, and thus the reliability is high. Therefore, an averaging process is performed on the offset values 206 sequentially derived in these states by increasing the weight of the newly derived temporary offset value 212 as compared to the non-straight running state. This is equivalent to using a forgetting factor such that the influence of the past temporary offset value 212 becomes small.

  On the other hand, during non-straight running, there may be an error or the like in Δθ obtained from the GPS azimuth change amount of Equation (4) or the average inclination angle α of the vehicle. Here, since the drift of the temporary offset value 212 is due to the influence of temperature or the like, it is presumed that the fluctuation of the temporary offset value 212 has a characteristic having a certain continuity. Therefore, by using a low-pass filter suitable for the characteristic, it is possible to absorb an error included in the offset value derived from the equation (4). Specifically, the low-pass filter suitable for the characteristic corresponds to using a forgetting factor that increases the influence of the past temporary offset value 212.

  FIG. 5 shows a configuration of the forgetting factor control unit 78. The forgetting factor control unit 78 includes a GPS azimuth change calculation unit 80, a self-contained navigation azimuth change calculation unit 82, a difference calculation unit 84, a difference absolute value calculation unit 86, and a forgetting factor calculation unit 88. The GPS azimuth change calculation unit 80 and the self-contained navigation azimuth change calculation unit 82 receive the storage data 210 output from the positioning data storage unit 32. The GPS azimuth change calculation unit 80 calculates a GPS azimuth change amount (hereinafter referred to as “GPS azimuth change amount”) in a predetermined period from the GPS azimuth data included in the stored data 210, and the GPS azimuth change amount is a difference calculation unit. 84. The self-contained navigation azimuth change calculation unit 82 calculates the angular velocity using the equation (1) from the angular velocity data and the inclination angle included in the storage data 210, the sensitivity coefficient 208, and the temporary offset value 212, and the angular velocity is determined over a predetermined period. By accumulating, an amount of change in direction due to self-contained navigation (hereinafter referred to as “independent amount of change in self-contained navigation”) is calculated. The autonomous navigation azimuth change calculation unit 82 outputs the independent navigation azimuth change amount to the difference calculation unit 84.

  The difference calculation unit 84 inputs the GPS azimuth change amount from the GPS azimuth change calculation unit 80 and also inputs the self-contained navigation azimuth change amount from the self-contained navigation azimuth change calculation unit 82. The difference calculation unit 84 calculates a difference value between the GPS azimuth change amount and the independent navigation azimuth change amount, and outputs the difference value to the difference absolute value calculation unit 86. The difference absolute value calculation unit 86 sequentially inputs the difference values from the difference calculation unit 84. The difference absolute value calculation unit 86 compares the difference value with the previous difference value, and derives the absolute value of these differences. The absolute value corresponds to the absolute value of the change amount of the difference value. For example, when the input value is 0.5 (deg) and the last input value is 0.3 (deg), the absolute value of the change amount is 0.2. The difference absolute value calculation unit 86 outputs the absolute value of the change amount to the forgetting coefficient calculation unit 88.

  The forgetting factor calculation unit 88 sequentially inputs the absolute value from the difference absolute value calculation unit 86. The forgetting factor calculation unit 88 derives the amount of change in the absolute value over a certain period, and adjusts the forgetting factor “α2” in the offset value filter processing unit 44 based on the amount of change in the absolute value. Specifically, when the change amount of the absolute value is equal to or larger than the seventh threshold value, the control is performed so that α2 is increased by estimating that the actual fluctuation of the offset value cannot be followed. If it is smaller than the threshold value, it is determined that it can follow and control is performed so that α2 becomes smaller. That is, the forgetting factor calculation unit 88 sets the forgetting factor “α2” such that the influence of the newly derived temporary offset value 212 becomes larger in the derivation of the offset value of the angular velocity sensor 26 as the change amount of the absolute value increases. . For example, when the change amount of the absolute value is 0.1 (deg) or more, the forgetting factor calculation unit 88 performs processing such as adding 0.01 to α2. Further, the seventh threshold value and the eighth threshold value may be the same value, for example, “0”. As a result, the forgetting factor calculation unit 88 updates α2 in the table of FIG. Here, there may be a case where the storage data 210 is not input. In this case, α2 in the table of FIG. 4 is updated with a preset initial value of α2. Further, here, when the non-straight running estimation unit 54 estimates the non-straight running state as the running state of the object, the forgetting factor calculation unit 88 performs the above-described processing.

  Returning to FIG. The forgetting factor setting unit 76 selects the forgetting factor “α1” or “α2” from the state indicated by the traveling state information 214 while referring to the table of FIG. As described above, the forgetting factor setting unit 76 changes the forgetting factor at the time of the filtering process according to the traveling state of the vehicle. Further, the offset value filter processing unit 44 adds α2 to the derived offset value 206 (hereinafter, the offset value 206 to which α2 is added is also referred to as “offset value 206”).

  FIG. 6 shows the configuration of the sensitivity coefficient calculation unit 30. The sensitivity coefficient calculation unit 30 includes a sensitivity coefficient derivation unit 90, a sensitivity coefficient filter unit 92, and a forgetting factor control unit 94. The sensitivity coefficient deriving unit 90 receives the GPS positioning data 200, the output signal 202, and the tilt angle 204. The sensitivity coefficient calculation unit 30 also receives an offset value 206. The sensitivity coefficient deriving unit 90 sequentially derives temporary sensitivity coefficients of the angular velocity sensor 26 based on the GPS positioning data 200, the output signal 202, the tilt angle 204, and the offset value 206.

Specifically, when the GPS positioning data 200 indicates that the GPS azimuth is valid, the sensitivity coefficient deriving unit 90 provides a temporary sensitivity coefficient of the angular velocity sensor 26 at the GPS azimuth sampling interval as follows. Is calculated.
Gsensitivity = (1 / n · ΣGout−Goffset) / Δθ / cos (α) (6)
Here, Goffset is input from an offset value calculation unit 28 (not shown), but it is possible that the offset value 206 has not yet been calculated in a state such as immediately after activation of the angular velocity calculation apparatus 100. Since equation (6) includes division by Δθ, the sensitivity coefficient is calculated when Δθ is equal to or greater than a predetermined value. When the value of Δθ is equal to or smaller than the predetermined value, the sensitivity coefficient deriving unit 90 outputs the sensitivity coefficient corrected immediately before.

  The sensitivity coefficient filter unit 92 inputs the temporary sensitivity coefficient sequentially derived by the sensitivity coefficient deriving unit 90. The sensitivity coefficient filter unit 92 derives the sensitivity coefficient 208 of the angular velocity sensor 26 by performing statistical processing on the temporary sensitivity coefficient. Similar to the offset value filter processing unit 44 shown in FIG. 3, the sensitivity coefficient filter unit 92 is configured with an IIR filter, and the IIR filter configures a low-pass filter. As a result, Δθ obtained from the GPS azimuth change amount in Equation (6) and the error included in the average inclination angle α of the vehicle are absorbed. Further, the sensitivity coefficient filter unit 92 sets a forgetting factor in the IIR filter based on an instruction from the forgetting factor control unit 94.

Specifically, the sensitivity coefficient 208 at the time t: S (t) is expressed as follows.
S (t) = αiGsensitivity (t) + (1-αi) S (t−1) (7)
Gsensitivity (t) is a temporary sensitivity coefficient at time t. That is, as αi increases, the effect of Gsensititivity (t) in S (t) increases, and as αi decreases, the effect of S (t−1) in S (t) increases. This corresponds to an increase in the influence of the new temporary sensitivity coefficient in the former case and an increase in the influence of the past sensitivity coefficient 208 in the latter case.

  The forgetting factor control unit 94 changes the forgetting factor in the sensitivity coefficient filter unit 92 according to the forgetting factor α2 of the offset value 206. This is equivalent to changing the forgetting factor in the statistical processing in the sensitivity coefficient filter unit 92 according to the degree to which the offset value filter processing unit 44 updates the offset value of the angular velocity sensor. Further, the forgetting factor control unit 94 sets the use of the changed forgetting factor in the sensitivity factor filter unit 92. FIG. 7 shows a data structure of a table stored in the sensitivity coefficient filter unit 92. As shown, a condition column 400 and a forgetting factor column 402 are shown. In the condition column 400, “more than x” and “less than x” are shown as conditions of the forgetting factor included in the offset value 206 for determining the forgetting factor. In the forgetting factor column 402, the value of the forgetting factor corresponding to each condition in the condition column 400 is shown. Specifically, the forgetting factor α10 is set for “x or more” and the forgetting factor α11 is defined for “less than x”. Further, a relationship of α10 <α11 is defined. In other words, since the variation of the offset value 206 is large when x is greater than or equal to x, an averaging process is performed in which the weighting of the newly derived temporary sensitivity coefficient is smaller than when it is less than x.

  In addition, here, an example is shown in which a temporary sensitivity coefficient is calculated at the sampling interval of the GPS direction. However, when the variation in Goffset and α is very small, or when the value of Δθ does not exceed a predetermined value, The interval may be increased. That is, the derivation of the provisional sensitivity coefficient is not limited to the GPS azimuth sampling interval. Further, when the forgetting factor α2 for deriving the offset value 206 is greater than or equal to x, the interval for calculating the temporary sensitivity coefficient may be made smaller than when x is less than x. In other words, as the degree of updating the offset value of the angular velocity sensor in the offset value filter processing unit 44 increases, the period for deriving one of the temporary sensitivity coefficients of the angular velocity sensor may be shortened.

  The operation of the angular velocity calculation apparatus 100 having the above configuration will be described. FIG. 8 is a flowchart showing a procedure for deriving an offset value by the angular velocity calculation apparatus 100. The validity determination unit 22 determines the validity of the two GPS positioning data 200 measured by the GPS positioning unit 20 (S10). The two GPS positioning data 200 correspond to the GPS positioning data 200 at a timing separated by the sampling interval time. If it is not valid (N in S10), it waits. If both are valid (Y in S10), the offset value calculation unit 28 determines that the total value of the GPS azimuth change amount of the vehicle at the sampling interval of the GPS positioning data 200 and the output signal 202 of the angular velocity sensor 26, and the inclination detection unit 24 The vehicle inclination angle 204 to be output and the sensitivity coefficient 208 output by the sensitivity coefficient calculation unit 30 are acquired (S12).

  The state estimation unit 40 determines whether the traveling state of the vehicle is a stop or a straight traveling state based on the acquired various information (S14). If the vehicle is in a stop or straight travel state (Y in S14), the stop offset value deriving unit 56 or the straight travel offset value deriving unit 58 calculates the temporary offset value 212 of the angular velocity sensor 26 based on the acquired various information. (S16). The offset value filter processing unit 44 executes filter processing with the forgetting factor α1 (S18). On the other hand, if the vehicle is not stopped or traveling straight (N in S14), the non-straight traveling offset value deriving unit 60 calculates the temporary offset value 212 of the angular velocity sensor 26 based on the acquired various information (S20). The offset value filter processing unit 44 executes filter processing with the forgetting factor α2 (S22).

  FIG. 9 is a flowchart showing a procedure for deriving the forgetting factor α2 by the angular velocity calculating apparatus 100. When the storage data 210 is not input from the positioning data storage unit 32 (N in S70), the process waits. When the stored data 210 is input from the positioning data storage unit 32 (Y in S70), the forgetting factor control unit 78 calculates the GPS azimuth change amount for a predetermined period in the GPS azimuth change calculation unit 80, and calculates the autonomous navigation azimuth change. The amount of change in the direction of self-contained navigation is calculated in the unit 82 (S72). The difference calculation unit 84 calculates the difference between the respective azimuth change amounts input from the GPS azimuth change calculation unit 80 and the autonomous navigation azimuth change calculation unit 82 (S74), and outputs the difference to the absolute difference calculation unit 86. The difference absolute value calculation unit 86 calculates the absolute value of the azimuth change difference (S76), and outputs the difference from the previous value to the forgetting coefficient calculation unit 88. The forgetting factor calculation unit 88 adds a predetermined value to α2 when the amount of change in the absolute value sequentially input is equal to or greater than the seventh threshold value (Y in S78) (S80). If the change amount of the absolute value is less than the seventh threshold value (N of S78), it is further determined whether or not the change amount of the absolute value is smaller than the eighth threshold value (S82). If the absolute value change amount is smaller than the eighth threshold value (Y in S82), the forgetting factor calculation unit 88 subtracts a predetermined value from α2 (S84). If the change amount of the absolute value is not smaller than the eighth threshold value (N in S82), the process is terminated.

  FIG. 10 is a flowchart showing the procedure for deriving the sensitivity coefficient by the angular velocity calculation apparatus 100. The validity determination unit 22 determines the validity of the two GPS positioning data 200 measured by the GPS positioning unit 20 (S40). The two GPS positioning data 200 correspond to the GPS positioning data 200 at a timing separated by the sampling interval time. If it is not valid (N in S40), it waits. If both are valid (Y in S40), the sensitivity coefficient calculation unit 30 determines that the total value of the GPS azimuth change amount of the vehicle at the sampling interval of the GPS positioning data 200 and the output signal 202 of the angular velocity sensor 26, and the inclination detection unit 24 The vehicle inclination angle 204 to be output and the offset value 206 output by the offset value calculator 28 are acquired (S42).

  If the sensitivity coefficient deriving unit 90 determines that the acquired GPS azimuth change amount is not equal to or greater than the predetermined value (N in S44), the process returns to step 40. On the other hand, if the sensitivity coefficient deriving unit 90 determines that the acquired GPS azimuth change amount is greater than or equal to a predetermined value (Y in S44), the temporary coefficient of sensitivity of the angular velocity sensor 26 is derived based on the acquired various information ( S46). The sensitivity coefficient filter unit 92 determines whether or not the forgetting factor included in the offset value 206 is greater than or equal to a threshold value (S48). If it is greater than or equal to the threshold value (Y in S48), α10 shown in FIG. The forgetting coefficient is set, and the filter process is executed for the temporary sensitivity coefficient (S50). If it is not equal to or greater than the threshold value (N in S48), the sensitivity coefficient filter unit 92 sets α11 as a forgetting coefficient, and executes filter processing on the temporary sensitivity coefficient (S52).

  According to the embodiment of the present invention, the forgetting factor is set based on the change amount of the difference between the GPS azimuth change amount and the autonomous navigation azimuth change amount, so the forgetting factor suitable for the current temporary offset value is set. it can. In addition, since a forgetting factor suitable for the current temporary offset value is set, errors included in the offset value can be reduced even in a short period. Also, the absolute value of the difference between the GPS azimuth change and the self-contained navigation azimuth change is calculated, and as the absolute value change increases, the influence of the newly derived temporary offset value increases. Since the forgetting factor is set, it is possible to follow the actual fluctuation of the offset value. In addition, since the forgetting factor is set such that the influence of the newly derived temporary offset value becomes smaller as the change amount of the absolute value becomes smaller, the stability of the offset value can be improved. Further, since the adjustment of the forgetting factor is executed in the non-straight running state, the forgetting factor can be finely adjusted when the offset value tends to shift. Further, since fine adjustment of the forgetting factor is executed, it is possible to suppress the deterioration of the estimation accuracy of the offset value. In addition, since the deterioration of the offset value estimation accuracy is suppressed, the angular velocity estimation accuracy can be improved.

  In addition, since the forgetting coefficient for executing the statistical processing is set for the temporary sensitivity coefficient according to the forgetting coefficient for updating the offset value, the forgetting coefficient can be set according to the offset value drift. In addition, since the forgetting factor is set according to the drift of the offset value, the error included in the sensitivity factor can be reduced even in a short period. Moreover, since the forgetting factor is set according to the drift of the offset value, the accuracy of estimating the sensitivity factor can be improved. Moreover, since the estimation accuracy of the sensitivity coefficient is improved, the estimation property of the angular velocity can be improved. In addition, the smaller the forgetting factor for updating the offset value, the larger the forgetting factor when performing statistical processing on the temporary sensitivity factor, so a sensitivity factor that follows the actual fluctuation of the offset value is set. Can be derived. In addition, as the forgetting coefficient for updating the offset value increases, the forgetting coefficient when the statistical process is executed on the temporary sensitivity coefficient is also reduced, so that a highly stable sensitivity coefficient can be derived. Further, as the forgetting factor for updating the offset value of the angular velocity sensor increases, the period for deriving one of the temporary sensitivity coefficients of the angular velocity sensor is shortened, so that the influence of environmental changes can be reduced.

  In addition, the temporary offset value is derived according to the driving state, and the offset value is derived by filtering the temporary offset value while using the forgetting factor according to the driving state. Can be reduced. In addition, since the error included in the offset value is reduced, the accuracy of deriving the offset value can be improved. Moreover, since the inclination angle of the vehicle is taken into account for the offset value of the angular velocity sensor, the derivation accuracy can be further improved. Further, since the optimum offset value corresponding to the traveling state of the vehicle is derived in a short time such as the sampling interval of the GPS direction, it is possible to accurately follow the offset value drift.

  In addition to deriving a temporary sensitivity coefficient, the sensitivity coefficient is derived by filtering the temporary sensitivity coefficient while using a variable forgetting coefficient, thus reducing errors contained in the sensitivity coefficient even in a short period of time. it can. Further, since the error included in the sensitivity coefficient is reduced, the sensitivity coefficient derivation accuracy can be improved. Further, since two states are substantially defined as the running state and two types of provisional offset value derivation methods and forgetting factors α1 and α2 are prepared, the processing can be simplified. Further, since the sensitivity coefficient of the angular velocity sensor is calculated in consideration of the inclination angle of the vehicle and its variation, the derivation accuracy can be improved even when traveling on an inclined road. In addition, since the offset value drift can be accurately followed, the sensitivity coefficient can be accurately derived immediately after the navigation apparatus is activated. In addition, since the accuracy of deriving the offset value and the sensitivity coefficient is improved, the accuracy of deriving the angular velocity can be improved.

  In the above, this invention was demonstrated based on the Example. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. .

  In the embodiment of the present invention, the offset value calculation unit 28 and the sensitivity coefficient calculation unit 30 are based on the GPS azimuth included in the GPS positioning data 200 when calculating the equations (4) and (6). Δθ is used. However, the present invention is not limited thereto, and for example, the offset value calculation unit 28 and the sensitivity coefficient calculation unit 30 may use a road direction in which the vehicle is matched using a map database (not shown). The GPS positioning data 200 is used for matching the vehicle to the map database. According to this modification, the degree of freedom of the configuration of the angular velocity calculation device 100 can be improved.

  In the embodiment of the present invention, the inclination detector 24 calculates the vehicle inclination angle 204 using the GPS altitude. However, the present invention is not limited thereto, and for example, the tilt detection unit 24 may include an acceleration sensor, and the tilt angle 204 may be calculated using information from the acceleration sensor. Alternatively, the inclination detection unit 24 may use the altitude information of the road with which the vehicle is matched when the altitude information exists in the road information included in the map database (not shown). According to this modification, the inclination angle 204 can be derived with high accuracy.

  In the embodiment of the present invention, the offset value calculation unit 28 and the sensitivity coefficient calculation unit 30 use the inclination angle 204 when deriving the temporary offset value 212 and the temporary sensitivity coefficient. However, the present invention is not limited to this. For example, the tilt angle 204 may not be used. At that time, α in the equations (4) and (6) is set to zero. According to this modification, processing can be simplified.

  In the embodiment of the present invention, the state estimation unit 40 uses the GPS speed included in the GPS positioning data 200 to determine the stop state as the traveling state determination of the vehicle. However, the present invention is not limited to this. For example, the state estimation unit 40 may input a vehicle speed pulse signal of a vehicle from a pulse detection unit (not shown) and determine the stop state based on the vehicle speed pulse. Here, the pulse detection unit is connected to a speed sensor (not shown), and the speed sensor is installed in the middle of the speedometer cable that rotates in response to the rotation of the drive shaft, and the vehicle speed pulse accompanying the rotation of the drive shaft. Output a signal. According to this modification, the speed of the vehicle can be measured by various means.

  In the embodiment of the present invention, the validity determination unit 22 uses PDOP to determine the validity of the GPS positioning data 200. However, the present invention is not limited to this. For example, the validity determination unit 22 may use GDOP (Geometric Dilution Of Precision), HDOP (Horizontal Division Of Precision), or a combination thereof. According to this modification, various parameters can be used for determination.

  In the embodiment of the present invention, the offset value filter processing unit 44 and the sensitivity coefficient filter unit 92 are formed so as to include an IIR filter. However, the present invention is not limited to this. For example, the offset value filter processing unit 44 and the sensitivity coefficient filter unit 92 may be formed to include an FIR (Finite Impulse Response) filter. At that time, the forgetting factor is set as a tap factor. According to this modification, the degree of freedom of the filter configuration can be improved.

  In the embodiment of the present invention, the forgetting factor controller 78 adjusts the forgetting factor α2 when the non-straight running state is estimated. However, the present invention is not limited thereto. For example, the forgetting factor control unit 78 may adjust the forgetting factor α1 even when the straight traveling state is estimated. At that time, the forgetting factor control unit 78 increases the adjustment range of the forgetting factor α1 in the case of the straight traveling state than the adjustment range of the forgetting factor α2 in the case of the non-straight running state. According to the present modification, in this case, the adjustment range of the forgetting factor in the straight traveling state is made larger than the adjustment range of the forgetting factor in the non-straight running state, so that the actual fluctuation of the offset value can be followed.

  In the embodiment of the present invention, the forgetting factor control unit 78 defines the same value for the forgetting factor for the stop state and the forgetting factor for the straight traveling state. However, the present invention is not limited to this. For example, the forgetting factor control unit 78 may set different values for these. It can be said that different processing is performed for each of the three states. According to the present modification, three forgetting factors are prepared for the three states as the running state, so that filter processing suitable for each state can be realized.

  DESCRIPTION OF SYMBOLS 10 Measurement part, 12 Parameter calculation part, 14 Angular velocity conversion part, 20 GPS positioning part, 22 Effectiveness determination part, 24 Inclination detection part, 26 Angular velocity sensor, 28 Offset value calculation part, 30 Sensitivity coefficient calculation part, 32 Accumulation of positioning data , 34 control unit, 40 state estimation unit, 42 state-specific offset value derivation unit, 44 offset value filter processing unit, 50 stop estimation unit, 52 straight travel estimation unit, 54 non-straight travel estimation unit, 56 stop offset value derivation 58, straight running offset value derivation unit, 60 non-straight running offset value derivation unit, 70 αi multiplication unit, 72 addition unit, 74 1-αi multiplication unit, 76 forgetting factor setting unit, 78 forgetting factor control unit, 80 GPS azimuth change calculator 82 Autonomous navigation azimuth change calculator 84 Difference calculator 86 difference absolute value calculation unit, 88 forgetting coefficient calculation unit, 90 sensitivity coefficient derivation unit, 92 sensitivity coefficient filter unit, 94 forgetting factor control unit, 100 angular velocity calculation device.

Claims (6)

An acquisition unit that acquires positioning data of an object measured based on a signal from a GPS satellite and an angular velocity of the object output from an angular velocity sensor;
An offset value deriving unit that sequentially derives a temporary offset value of the angular velocity sensor by using at least the angular velocity acquired in the acquiring unit;
The offset value of the angular velocity sensor for correcting the angular velocity output from the angular velocity sensor is derived by performing statistical processing on the temporary offset value of the angular velocity sensor sequentially derived by the offset value deriving unit. An offset value filter processing unit,
The offset value filter processing unit
A first azimuth change amount is derived based on the positioning data acquired in the acquisition unit, and a second azimuth change amount is calculated based on the temporary offset value of the angular velocity sensor derived in the offset value derivation unit. A direction change amount deriving unit to derive,
A difference change amount derivation unit for deriving a change amount of a difference between the first azimuth change amount and the second azimuth change amount derived in the azimuth change amount derivation unit;
Based on the difference change amount derived in the difference change amount deriving unit, an adjustment unit that adjusts the forgetting factor in the statistical processing;
An angular velocity sensor correction device comprising:   The adjusting unit is configured to detect the angular velocity sensor when the absolute value change amount of the difference change amount derived by the difference change amount deriving unit increases or when the absolute value change amount of the difference change value is equal to or greater than a predetermined value. 2. The angular velocity sensor correction device according to claim 1, wherein the forgetting factor is adjusted so that the influence of the newly derived temporary offset value is increased in the derivation of the offset value. Based on the positioning data and angular velocity acquired in the acquisition unit, further comprising an estimation unit for estimating the traveling state of the object,
The offset value deriving unit uses the combination of the positioning data and the angular velocity acquired in the acquiring unit when the estimating unit estimates a non-straight driving state as the traveling state of the object, Temporary offset values are derived sequentially,
The angular velocity sensor correction device according to claim 1, wherein the adjustment unit adjusts a forgetting factor when the estimation unit estimates a non-straight running state as a running state of an object. The offset value deriving unit sequentially derives a temporary offset value of the angular velocity sensor by using the angular velocity acquired in the acquiring unit when the estimating unit estimates a straight traveling state as the traveling state of the object. And
The adjusting unit performs adjustment of the forgetting factor even when the estimating unit estimates the straight traveling state as the traveling state of the object, and travels straight ahead of the adjustment range of the forgetting factor in the non-straight traveling state. 4. The angular velocity sensor correction device according to claim 3, wherein the adjustment range of the forgetting factor in the running state is increased. Obtaining positioning data of an object measured based on a signal from a GPS satellite and an angular velocity of the object output from an angular velocity sensor;
Sequentially deriving a temporary offset value of the angular velocity sensor by using at least the acquired angular velocity;
Deriving an offset value of the angular velocity sensor for correcting the angular velocity output from the angular velocity sensor by performing statistical processing on the temporary offset value of the angular velocity sensor sequentially derived,
Deriving the offset value of the angular velocity sensor includes
Deriving a first azimuth change amount based on the acquired positioning data, and deriving a second azimuth change amount based on the derived temporary offset value of the angular velocity sensor;
Deriving a change amount of a difference between the derived first azimuth change amount and the second azimuth change amount;
Adjusting the forgetting factor in the statistical process based on the amount of change in the derived difference;
An angular velocity sensor correction method comprising:   In the step of adjusting, as the amount of change in the absolute value of the amount of change in the derived difference increases, or when the amount of change in the absolute value of the amount of change in the difference exceeds a predetermined value, the offset value of the angular velocity sensor is derived. 6. The angular velocity sensor correction method according to claim 5, wherein the forgetting factor is adjusted so that the influence of the newly derived temporary offset value is increased.

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