JP2009115714A - Method and device for measuring speed of mobile unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for speed measuring, accurately determining the moving speed of the each passing moment of a mobile unit, since a method by GPS and a method by an accelerometer have been employed as the method of determining the speed of the mobile unit, but they have respective advantages and disadvantages, and a method using the both while suitably switching these methods has been also known, but the moving speed of the each passing moment cannot be measured accurately. <P>SOLUTION: A position measuring device for measuring a position and an acceleration measuring device for measuring acceleration are installed in the mobile unit, a period that is time interval for calculating the difference of the position of the position measuring device and is an averaged time when the output value of the acceleration measuring device is movement-averaged after integration is determined in response to the variation width of the output value of the acceleration measuring device in a predetermined moving time of the mobile unit, the average moving speed obtained by the position measuring device and a moving speed variation component obtained by the acceleration measuring device are compounded, and the speed of the mobile unit is determined. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a speed method and a speed measurement device that accurately measure an instantaneous speed of a moving body such as a vehicle or a ship. Conventionally, when grasping the speed of a vehicle or a ship, it is not always necessary to grasp even the instantaneous speed, and it is sufficient as a function if an average speed can be grasped and displayed. However, when other measuring devices (for example, Doppler radar, Doppler soda, etc.) are mounted on the moving body to measure the speed of objects such as wind speed and objects, radio waves and sound waves are transmitted and received by other measuring devices. Every time, it is necessary to accurately measure the instantaneous ground speed of the moving body and correct the output value of other measuring devices. At this time, it is assumed that moving bodies such as vehicles and ships are affected by undulations of land that is not leveled or by waves in the ocean, and the movement speed is not constant and varies from time to time. Therefore, when the moving speed of a vehicle or a ship is not constant, it is necessary to accurately measure the moving speed at that moment. That is, a speed measurement system with high time resolution and high accuracy is required. An object of the present invention is to provide a moving speed measuring method and apparatus that satisfy the above requirements and have high time resolution and high accuracy.

  When measuring the speed of a vehicle or a ship, there is a method of using a position measuring device (hereinafter sometimes abbreviated as GPS), and a method of calculating a moving speed by dividing the difference of continuous position data by GPS by time There is. In this case, an average speed having a long averaging time is easily obtained, but it is difficult to obtain an instantaneous speed with high accuracy.

  In addition, when measuring the speed of a vehicle or a ship, there is a method of calculating the speed by integrating an acceleration measurement device (hereinafter, abbreviated as an accelerometer) and integrating the measured value of the accelerometer (for example, Patent Document 1). In this case, the acceleration error is accumulated as the time passes, and the error increases. Therefore, if the operation time is long, it is difficult to obtain the speed. Furthermore, there is a drawback that a gravitational acceleration component is included in the horizontal acceleration when the vehicle or ship moving body is tilted.

  In addition, a speed measuring device that combines a GPS and an accelerometer and switches between these devices depending on the radio wave reception state of the GPS has been proposed (see, for example, Patent Documents 2 and 3). However, when the GPS and the accelerometer are switched and used in this way, the instantaneous moving speed cannot be measured with high accuracy.

  There is also a device that measures the ground speed or water speed of a ship on the ocean using the ultrasonic Doppler effect. In this case, if the water depth becomes deep, the measurement of speed becomes difficult.

In addition, about the necessity of calculating | requiring the speed | velocity | rate of a moving body accurately, and the field | area of practical use, there exists a paper publication of the inventors of this application (for example, refer nonpatent literature 1).
JP 2005-156185 A JP-A-7-280826 JP-A-7-280828 Lecture paper "Study on Mobile Wind Observation Method Applied to Offshore Wind Power Generation, 28th Symposium on Wind Energy Utilization" (November 2006), pp. 345-348

  As described above, when calculating the speed by dividing the difference between continuous position data by GPS by time, the time interval of position data used for calculating the difference is set short in order to obtain the instantaneous speed. This will increase the speed error. On the other hand, if the time interval is set longer, the average speed error in the set time becomes smaller, but the instantaneous speed cannot be obtained.

  Further, when the velocity is calculated by integrating the measured values of the accelerometer, the acceleration error is accumulated as time elapses, making it difficult to measure for a long time. Furthermore, when switching between GPS and accelerometers, the instantaneous and instantaneous moving speed cannot be measured with high accuracy.

  The present invention has been made to solve the above-described problems, and can determine the moving speed of a moving object at an instantaneous moment with high accuracy, that is, with high time resolution and high speed. An object of the present invention is to provide a measurement method and apparatus.

  According to the first aspect of the present invention, a position measuring device for measuring a position and an acceleration measuring device for measuring acceleration are installed on a moving body, and an output value of the acceleration measuring apparatus during a predetermined moving time of the moving body. The time interval for calculating the position difference of the position measuring device according to the change width of the position measuring device and the time for averaging the moving average after the output value of the acceleration measuring device is integrated is determined. A method for measuring the speed of a moving body, comprising: combining an average moving speed obtained from the position measuring device and a moving speed fluctuation component obtained from the acceleration measuring device to obtain a speed of the moving body. .

  According to the second aspect of the present invention, an error in the output value of the position measurement device caused by movement is estimated using a change width of the output value of the acceleration measurement device, and is determined by the estimated error. 2. The movement according to claim 1, wherein a moving body position is obtained by adding a weight and a moving average of position output values is obtained, and a moving body speed is obtained from a difference between successive position outputs. It is a method for measuring the speed of the body.

  The invention according to claim 3 is characterized in that the change width of the output value of the acceleration measuring device is obtained by the root mean square of the acceleration output value, and the speed of the moving body according to claim 1 or 2 This is a measurement method.

  The invention according to claim 4 has a position measuring device for measuring a position and an acceleration measuring device for measuring acceleration, and according to a change width of an output value of the acceleration measuring device during a predetermined moving time of the moving body. Determining a time that is a time interval for calculating a position difference of the position measuring device and that is an averaging time when moving and averaging the output values of the acceleration measuring device after integration. A moving body speed measuring device comprising a circuit for determining the speed of a moving body by synthesizing the average moving speed obtained from the above and the moving speed fluctuation component obtained from the acceleration measuring device.

  According to the fifth aspect of the present invention, an error in the output value of the position measuring device caused by movement is estimated using a change width of the output value of the acceleration measuring device, and is determined by the estimated error. 5. The apparatus according to claim 4, further comprising a circuit that obtains the position of the moving body by moving and averaging the output values of the positions by adding weights, and further obtains the speed of the moving body from a difference between successive position outputs. It is a moving body speed measurement apparatus of description.

  The invention according to claim 6 further includes a circuit for obtaining a change width of the output value of the acceleration measuring device by a root mean square of the acceleration output value. It is a body speed measurement device.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a moving body in which a moving speed changes fluctuate | variably with a wave or a road surface condition in the moving body in a ship, a vehicle, etc., it becomes possible to obtain | require the instantaneous speed with high precision.

  Also, when measuring other object measuring devices (such as Doppler radar, Doppler soda, etc.) on a moving body such as a ship or a vehicle and measuring the speed of an object such as wind speed or an object, measure the speed of the object. It is necessary to correct the output value of other measuring devices by measuring the moving speed of the moving object at the moment. When wind observation equipment, radar, etc. are mounted on the moving body in this way, the output value of the wind observation equipment, radar, etc. mounted on the mobile body is obtained using the output value of the moving speed with high time resolution obtained by the present invention. By correcting, observation by wind observation equipment, radar, etc. becomes possible while moving.

  FIG. 1 is a diagram for conceptually explaining a moving speed measuring method and apparatus according to the present invention. Each block in FIG. 1 represents a program for calculating the output of a sensor installed on a moving body. As shown in FIG. 1, a moving body 1 such as a ship or a vehicle is provided with a GPS 2 and a three-axis accelerometer 3, more generally, a three-axis gyro 4 and a compass 5. An inclinometer can be used instead of the triaxial gyro.

FIG. 2 is a diagram for conceptually explaining coordinate conversion for correcting the inclination of a vehicle or a ship. The coordinate axes (X _S , Y _S , Z _S ) represent coordinate axes fixed to the moving body, and the coordinate axes (X _G , Y _G , Z _G ) are absolute coordinate systems (east-west) based on the azimuth axis of the observation site. This represents the coordinate axes of the local plane Cartesian coordinate system with the north-south and vertical directions as axes.

  Since the acceleration data changes depending on the inclination angle of the measuring device, it is necessary to convert the acceleration data back to the absolute coordinate system. Coordinate conversion is performed from the coordinate system fixed to the moving body (measuring device) shown in FIG. 2 to the absolute coordinate system of the observation site (local plane rectangular coordinate system with the east-west-north-north and vertical directions as axes) by the following procedure.

The acquired raw acceleration vector is A = (a _X , a _Y , a _Z ), the acceleration vector after coordinate transformation is B = (b _X , b _Y , b _Z ), and as shown in FIG. When the pitch angle is θ, the roll angle is φ, and the yaw angle is Ψ, the coordinate transformation for correcting the tilt angle / azimuth angle is calculated by the equation (1).

・・・（１）

... (1)

  Further, in order to remove the component of the gravitational acceleration g, the gravitational acceleration g is corrected from the acceleration vector by the equation (2) (the equations (1) and (2) are the acceleration coordinate conversion and the gravity acceleration correction in FIG. 1). Corresponding to program 7).

・・・（２）

... (2)

In order to obtain the change width of the output value of the corrected acceleration vector C = (c _X , c _Y , c _Z ), for example, the root mean square (hereinafter sometimes abbreviated as RMS) is calculated (see FIG. 1). Corresponds to acceleration RMS calculation program 8). The root mean square (RMS) is an index indicating the magnitude of acceleration fluctuation, that is, the amplitude of the acceleration output value. For example, RMS in N pieces of data [x ₁ , x ₂ , x ₃ ,..., X _N ] is defined by equation (3).

・・・（３）

... (3)

  Based on the RMS value, as will be described later, the time S is a time interval when the speed is obtained from the output of successive positions, and is the averaging time when the output value of the accelerometer is averaged after integration. (Corresponding to the averaging time determination program in FIG. 1). FIG. 3 is a graph showing an example of a function for determining the time S (seconds) from the RMS value of acceleration. Further, as will be described later, this RMS value is used to estimate an error in the GPS output value caused by movement.

Next, the acceleration time series data C _i obtained by the equation (2) is integrated by the equation (4) (corresponding to the integration calculation program 10 of FIG. 1), and the provisional speed V _ai (the waveform 10a of FIG. 5) is obtained. Corresponding to). The integration of equation (4) corresponds to obtaining the speed by time integration of acceleration.

・・・（４）

... (4)

This temporary speed V _ai (waveform 10a in FIG. 5) is averaged during the averaging time S (corresponding to the moving average calculation program 11 in FIG. 1), and the moving average speed V _bi of the speed V _ai (FIG. 5). Waveform 11a) is calculated.

Further, from the difference between the provisional speed V _ai and the speed V _bi obtained by moving average V _ai , the movement speed fluctuation component G _i (the same as the waveform bar V _i on the left side of the equation (5), the waveform of FIG. 12a) is calculated by equation (5).

・・・（５）

... (5)

On the other hand, the position data obtained by GPS adds weight M _i to the GPS time-series data P _i , and calculates the moving average value Q _i of the position using the moving average method shown in equation (5). Performed (corresponding to the GPS data moving average calculation program 14 in FIG. 1).

・・・（６）

... (6)

The weight M _i in the equation (6) is calculated by the equation (7) (corresponding to the weight function setting program 13 in FIG. 1).

・・・（７）

... (7)

In the equation (7), the root mean square (RMS) σ _rms (m / s ² ) of the acceleration data C described above is used as an error in position analysis due to fluctuations in the moving speed of the moving body. Further, δ is an error (m) that GPS originally has. An example of the weight M _i added to the GPS data P _i in the time interval Δ _ti (seconds) from the position data P _i determined based on the equation (7) is shown in FIG.

Based on the moving average value Q _i obtained by the equations (6) and (7), the average moving speed is obtained as follows. For continuous position data Q _i (moving average value), assuming that the initial position in the time interval S centered on the time to be obtained is Q _ini and the final position is Q _end , the position difference ( By dividing the distance) by the time interval S, the average moving speed H _{i at} the position Q _i (the waveform 15a in FIG. 6 which is the same as the V _i with the straight bar on the left side of the equation (8)) is calculated (FIG. 1). Corresponding to the calculation program 15 of the average movement speed of

・・・（８）

... (8)

Finally, the average speed H _i (waveform 15a in FIG. 6) and the moving speed fluctuation component G _i (waveform 12a in FIGS. 5 and 6) are synthesized by equation (9) to obtain the moving speed V _i (in FIG. 6). Waveform 16a) is obtained as output.

・・・（９）

... (9)

  As described above, the moving body speed / position measuring method and the measuring apparatus according to the present embodiment can realize moving speed measurement capable of measuring the moving speed of the moving body with high time resolution and accuracy. In addition, in this document, there are characters in the expressions (1) to (9) and characters in sentences other than the expression that are not italic and not italic, or that differ in the thickness of the line. It means the same thing with no difference.

  Hereinafter, the movement speed measurement system according to the present invention is actually mounted on a ship and will be described based on data acquired when the ship navigates on the ocean where a large speed change due to waves occurs.

  The acceleration obtained by the triaxial accelerometer 3 is corrected in inclination angle by the coordinate transformation of the equation (1), and the gravitational acceleration g is removed by the equation (2). When the coordinate conversion is performed and the acceleration obtained by correcting the gravitational acceleration is integrated over time, a temporary velocity waveform (10a in FIG. 5) obtained by integrating the acceleration is obtained.

Further, the RMS defined by the equation (3) is calculated from the acceleration obtained by coordinate transformation and correcting the gravitational acceleration (here, RMS = 0.2 m / s ² ). This is a time interval for calculating the GPS position difference from the calculated acceleration RMS based on the function of FIG. 3, and is an averaging time when the output value of the acceleration measuring device is moving averaged after integration. Time S (seconds) is determined (here, S = 20 seconds is determined).

  A provisional speed obtained by integrating the acceleration over time (waveform 10a in FIG. 5) is moving-averaged based on the averaging time S (waveform 11a in FIG. 5). A deviation of a provisional speed (waveform 10a in FIG. 5) obtained by time-integrating acceleration with respect to the moving average speed (waveform 11a in FIG. 5) is calculated by the equation (5), and a moving speed fluctuation component (waveform 12a in FIG. 5) is calculated. )

On the other hand, the average component of the moving speed is calculated from the GPS data by the following procedure. First, the weight function M _i (FIG. 4) to be added to the GPS data is determined from the calculated acceleration RMS value according to the equation (7). Next, the averaging time is set to S (seconds), the weighting function is set to M _i (FIG. 4), and the GPS position data is moving averaged based on the equation (8). Based on the moving averaged GPS position data, an average speed (waveform 15a in FIG. 6) in the time interval S (seconds) is calculated based on Equation (8).

  Finally, the moving speed fluctuation component (waveform 12a in FIGS. 5 and 6) and the average component (waveform 15a in FIG. 6) are synthesized by equation (9) to output the moving speed (waveform 16a in FIG. 6). .

On the other hand, as an application of the first embodiment, the position of the moving moving body can be determined with high accuracy by the following procedure.

First, the acceleration obtained by the three-axis accelerometer 3 is corrected in inclination angle by the coordinate transformation of equation (1), and the gravitational acceleration g is removed by equation (2). Next, the RMS defined by the equation (3) is calculated from the acceleration obtained by coordinate conversion and correcting the gravitational acceleration (here, RMS = 0.2 m / s ² ). A weight function M _i (FIG. 4) to be added to the GPS data is determined from the calculated RMS value of acceleration by Equation (7). Based on the equation (8), the weighting function is M _i (FIG. 4), and the position of the moving moving body is determined with high accuracy by moving and averaging the GPS position data.

  The present invention makes it possible to measure the speed of a moving body, such as a ship or a vehicle, whose speed fluctuates drastically depending on the wave and road surface conditions with high time resolution and high accuracy. This is useful for higher resolution and higher resolution.

  By using the moving speed measuring method and apparatus according to the present invention, other measuring devices (for example, Doppler radar, Doppler soda, etc.) are mounted on the moving body to measure the speed of an object such as a wind speed or an object while moving. can do. This measurement can be performed by correcting the instantaneous ground speed of the moving object from the output value obtained by transmitting / receiving radio waves / sound waves using a mounted radar or the like.

It is a flowchart for demonstrating the flow to the moving speed output by one Example of this invention. It is a figure for demonstrating the coordinate transformation from the coordinate system fixed to the moving body to an absolute coordinate system. It is the figure which showed an example of the function which determines time S (second) from the RMS value of acceleration. It is the figure which showed an example of the weight function used for a moving average as a graph. It is the figure which showed the example of analysis of the moving speed fluctuation | variation component (deviation) with the time series waveform. It is the figure which showed the analysis example of the final moving speed by the time series waveform.

Explanation of symbols

1 Mobile 2 GPS
3 3-axis accelerometer 4 3-axis gyro or inclinometer 5 Compass 6 Memory (data storage device)
7 Accelerometer coordinate conversion / gravity acceleration correction program 8 Acceleration RMS (root mean square) calculation program 9 Averaging time determination program 10 Integration calculation program 11 Moving average calculation program 12 Deviation calculation program 13 GPS data weight function Setting program 14 GPS data moving average program 15 Average moving speed calculation program 16 Moving speed synthesis program 10a Time series waveform of speed obtained by accumulating acceleration (calculated by integration calculation program 10)
11a Time-series data of moving average speed (calculated by moving average calculation program 11)
12a Time-series waveform of movement speed fluctuation component (calculated by deviation calculation program 12)
15a Time series waveform of average speed (calculated by the average speed calculation program 15)
16a Time series waveform of synthesized final moving speed (calculated by moving speed synthesis program 16)

Claims (6)

  A position measuring device for measuring a position and an acceleration measuring device for measuring an acceleration are installed on a moving body, and the position measuring device according to a change width of an output value of the acceleration measuring device during a predetermined moving time of the moving body. Is a time interval for calculating the difference between the positions of the acceleration measuring device, and determines the time that is the averaging time for moving average after integrating the output value of the acceleration measuring device, and the average movement obtained from the position measuring device A speed measurement method for a moving body, comprising combining a speed and a moving speed fluctuation component obtained from the acceleration measuring device to obtain the speed of the moving body.   The error of the output value of the position measuring device caused by the movement is estimated using the change width of the output value of the acceleration measuring device, and the weight determined by the estimated error is added to obtain the position output value. The method for measuring the speed of a moving body according to claim 1, wherein the position of the moving body is obtained by performing a moving average, and the speed of the moving body is obtained from a difference between successive position outputs.   The method for measuring the velocity of a moving body according to claim 1 or 2, wherein a change width of an output value of the acceleration measuring device is obtained by a root mean square of the acceleration output value.   A position measurement device for measuring a position and an acceleration measurement device for measuring an acceleration, and a position difference of the position measurement device according to a change width of an output value of the acceleration measurement device during a predetermined movement time of the moving body; Is a time interval for calculating the average moving speed obtained from the position measuring device, and determining the time that is the averaging time when moving average after integrating the output value of the acceleration measuring device, and the above A moving body speed measuring apparatus comprising a circuit for determining a moving body speed by combining moving speed fluctuation components obtained from an acceleration measuring apparatus.   The error of the output value of the position measuring device caused by moving is estimated using the change width of the output value of the acceleration measuring device, and a weight determined by the estimated error is added to obtain the position output value. 5. The moving body speed measuring apparatus according to claim 4, further comprising a circuit that obtains the position of the moving body by performing a moving average and obtains the speed of the moving body from a difference between successive position outputs.   6. The moving body speed measuring device according to claim 4, further comprising a circuit for obtaining a change width of the output value of the acceleration measuring device by a root mean square of the acceleration output value.

Images