JP7315924B2 - Information transmission device, mobile object, information transmission method, and information transmission program - Google Patents

Description

Article 30, Paragraph 2 of the Patent Act applies Article 30, Paragraph 2 applies, August 27, 2019 The Institute of Electronics, Information and Communication Engineers The Institute of Electronics, Information and Communication Engineers 2019 Society Conference Proceedings are published on the website, and Presented at the 2019 Institute of Electronics, Information and Communication Engineers Society Conference held at Osaka University on September 11, 2019

Article 30, Paragraph 2 of the Patent Law applies Article 30, Paragraph 2 applies, November 28, 2019 The Institute of Electronics, Information and Communication Engineers Smart Radio Study Group (SR) technical research report is published on the website, and Presented at the IEICE Smart Radio Study Group (SR) held at the Ishigaki Civic Hall on December 5, 1989.

The present invention relates to an information transmission apparatus, a mobile body, an information transmission method, and an information transmission program for efficiently transmitting information relating to the attitude of a mobile body such as an automobile.

As typified by the keywords CASE (Connected, Autonomous, Shared & Service, Electric), in recent years, the use of AI and IoT in automobiles has been rapidly progressing. In particular, in the connected field, vehicles or in-vehicle mobile devices sense various data related to driving with sensors, etc., analyze them at a high level with artificial intelligence, and provide useful information to drivers in real time. Connectivity is getting a lot of attention. For example, by installing sensors on the vehicle body dampers and recognizing the posture of the entire vehicle body while monitoring each damper, it is possible to realize quality control of the dampers.

By attaching wireless functions to sensors that recognize the state of objects, not just cars, technologies have been developed to record sensor information on the Internet, monitor conditions, control equipment, and collect billing information. Wireless communication for sensor information collection is called Wireless Sensor Network (WSN). However, as the use of wireless communication expands, exhaustion of frequencies, which are wireless communication resources, becomes a problem.

Therefore, as a method specialized for wireless sensor networks, the frequency, phase, duration, etc. of wireless signals are defined as radio physical quantities, and sensor information is changed in proportion to the radio physical quantities. (Patent Document 1, Patent Document 2). Such a method is called a (wireless communication parameter conversion type) collective information gathering method (PhyC-SN). This method can separate information even if the information sources are close to each other, and can collect information from all sensors in a small number of steps. For example, in the case of monitoring the damper, it is possible to collectively and simultaneously aggregate sensor information only by command notification without using external information (GPS, etc.).

JP 2013-187552 A JP 2017-046027 A

However, there is a possibility that a huge number of cars will be connected to the wireless sensor network in the future, and the problem of frequency depletion cannot be solved only by measures to improve transmission efficiency such as batch information collection methods. Therefore, it is necessary to reduce the amount of information itself by, for example, compressing information according to the characteristics of the information to be handled, together with information transmission technology such as the batch information collection method.

An information transmission device according to an aspect of the present disclosure is an information transmission device that transmits information related to the attitude of a mobile body having a plurality of wheels, is provided for each wheel, and measures position information in a three-axis coordinate system. a unit for modulating a carrier with a first physical quantity according to respective outputs relating to positional information on the x-axis and positional information on the y-axis among the outputs of the sensor group; One of the carriers modulated with the first physical quantity is further different from the first physical quantity according to at least 1-bit information related to the sign of the positional information on the z-axis among the outputs of the group. A unit that modulates with a second physical quantity , a carrier that is modulated with the first physical quantity and is not modulated with the second physical quantity, and a carrier that is modulated with the first physical quantity and the second physical quantity , and a unit for transmitting each in chronological order.

The moving object in the information transmission device may be an automobile, and the sensor groups may be provided in dampers respectively holding front, rear, left, and right wheels.

The x-axis in the information transmission device is the longitudinal axis of the moving body, the y-axis is the lateral axis of the moving body, and the z-axis is the vertical direction to the bottom surface of the moving body. It can be an axis.

The first physical quantity in the information transmission device may be the frequency of the carrier.

The second physical quantity in the information transmission device may be amplitude of the carrier.

A mobile body according to an aspect of the present disclosure is a mobile body having a vehicle body provided with a plurality of wheels, wherein a sensor group is provided for each of the wheels and measures and outputs position information in a three-axis coordinate system; a unit that modulates a carrier with a first physical quantity according to each output related to positional information on the x-axis and positional information on the y-axis among outputs of the sensor group; and a z-axis among the outputs of the sensor group A unit for modulating any one of the carriers modulated with the first physical quantity with a second physical quantity different from the first physical quantity according to at least 1-bit information related to the code of the position information above. and a carrier modulated with the first physical quantity but not modulated with the second physical quantity, and a carrier modulated with the first physical quantity and the second physical quantity , respectively, in chronological order. and

The x-axis of the moving body may be the front-rear axis of the vehicle body, and the y-axis may be the left-right axis of the vehicle body.

The first physical quantity in the moving body may be the frequency of the carrier.

The second physical quantity in the moving object may be amplitude of the carrier.

An information transmission method according to an aspect of the present disclosure is an information transmission method for transmitting information related to the attitude of a mobile body having a plurality of wheels, wherein each wheel is provided and position information is measured in a three-axis coordinate system. acquiring information from a group of sensors that output a carrier by a first physical quantity according to respective outputs related to positional information on the x-axis and positional information on the y-axis among the outputs of the group of sensors; and modulating the carrier to a first modulating value in accordance with at least one bit of information relating to the sign of the positional information on the z-axis among the outputs of the sensor group, together with the modulation with the first physical quantity. and modulating with a second physical quantity different from the physical quantity.

The first physical quantity in the information transmission method may be the frequency of the carrier.

The second physical quantity in the information transmission method may be amplitude of the carrier.

An information transmission program according to one aspect of the present disclosure is an information transmission program for transmitting information related to the attitude of a mobile body having a plurality of wheels, provided for each wheel, and measuring position information in a three-axis coordinate system. acquiring information from a group of sensors that output a carrier by a first physical quantity according to respective outputs related to positional information on the x-axis and positional information on the y-axis among the outputs of the group of sensors; and modulating the carrier to a first modulating value in accordance with at least one bit of information relating to the sign of the positional information on the z-axis among the outputs of the sensor group, together with the modulation with the first physical quantity. and modulating with a second physical quantity different from the physical quantity.

The first physical quantity in the information transmission program may be the frequency of the carrier.

The second physical quantity in the information transmission program may be amplitude of the carrier.

According to one aspect of the present disclosure, by compressing sensor information according to the characteristics of shaking or displacement of a moving body such as an automobile that runs on the ground, the amount of information to be transmitted in the collective information collection method can be greatly compressed. It is possible to achieve further effective use of frequencies.

1 is a conceptual diagram of a typical collective information gathering method model; FIG. FIG. 2 is an operation explanatory diagram of the collective information collection method of FIG. 1; It is a block diagram showing this embodiment. FIG. 4 is an explanatory diagram of sensor arrangement and detection position information in the present embodiment; 4 is a flow chart showing the operation of the processor of the embodiment; FIG. 4 is an image diagram of a transmission signal according to the present embodiment; It is a conceptual diagram which shows the effect of this Embodiment. FIG. 10 is a simulation diagram showing characteristics of displacement of a moving body according to the present embodiment; FIG. 4 is an explanatory diagram showing basic conditions in the present embodiment; 4 is a graph showing the results of Example 1 of the present disclosure; FIG. 4 is a graph showing the results of Example 2 of the present disclosure; FIG.

Hereinafter, an information transmission device according to an embodiment (hereinafter referred to as the present embodiment) according to one aspect of the present disclosure will be described in detail with reference to the drawings.

First, FIG. 1 illustrates a typical wireless communication parameter conversion type collective information gathering method (PhyC-SN) model. In FIG. 1, 201, 202, and 203 are sensors (#1, #2, and #3) each having a transmission function, and 204 is information aggregation for receiving all signals transmitted from each sensor (201, 202, and 203). station. A case where each sensor shifts the carrier frequency by a frequency corresponding to the observed temperature with respect to the frequency f ₀ of the carrier (carrier wave) for transmission will be described. For example, when the sensor 201 observes 19° C., it transmits _a signal with a frequency of 19+f ₀ (Hz) _. 2).

Information aggregation station 204 simultaneously receives signals from sensors 201, 202, and 203 and performs source identification and information separation. If the transmitter frequencies of the sensors are sufficiently far apart, the frequency components of 19 Hz, 24 Hz and 15 Hz can be detected by detecting the frequency spectrum of the received signal.

The present embodiment will be described below. FIG. 3 shows a block diagram of the information transmission device 1 in this embodiment. In FIG. 3, 2a, 2b, 2c, and 2d are motion sensors (sensors), respectively, and as shown in FIG. dotted line), and measures and outputs position information in a three-axis coordinate system. The position detected by an arbitrary motion sensor (for example, 2a) is, as shown in FIG. may be represented by (A _x , A _y , A _z ) with the vertical direction (z-axis direction) as a triaxial coordinate system, or the Euler angles (α, β, γ).

A processor 10 executes the processing shown in the flowchart of FIG. First, the positional information detected by the motion sensors 2a, 2b, 2c, and 2d ( _Ax , _Ay , _Az ), ( _Bx , _By , _Bz ), ( _Cx , _Cy , _Cz ), ( D _x , D _y , D _z ) are received (S11), and respective outputs (A _x , A _y ), (B _x , By ₎ , (C _x , C _y ) and (D _x , D _y ), the carrier is sequentially frequency-modulated (S12). Here, for each z-axis coordinate value (A _z , B _z , C _z , D _z ), position information is not sent, and only code information is converted into modulated signals of A _y , B _y , Cy _, D _y . superimpose. Specifically, the signals frequency-modulated by A _y , B _y , C _y and D _y are amplitude-modulated according to the signs of A _z , B _z , C _z and D _z (S13). .

Code information may be at least 1 bit. For example, when the position information (coordinates) detected by the motion sensor is (A _x , A _y , A _z )=(2.51, 1.12, 0.2), set “1”, (A _x , A When _{y 1} , A _z )=(1.22, 2.68, −1.34), “0” is taken as code information. Code information may have one or more bits, but since amplitude modulation is very susceptible to fading, the amount of information should be as small as possible. For example, since the value of the z-axis coordinate can be estimated from the values of the x- and y-axis coordinates, 1-bit code information is rather preferable.

In addition, in the present embodiment, it is assumed that the flowchart shown in FIG. 5 is executed by a program incorporated in the processor 10, but it is not necessary to be limited to this form. For example, all or part of each step (S11 to S14) may be realized by unitized hardware such as ASIC or FPGA. Also, the program does not have to be installed in the processor 10 in advance. For example, it may be supplied as an application at any time from a base station or server through a communication line.

Also, in FIG. 5, the amplitude modulation (S13) is performed after the frequency modulation (S12), but the order is not limited to this order. If amplitude modulation is applied in conjunction with frequency modulation, the reverse procedure may be performed. Also, amplitude modulation may be performed on the frequency-modulated signal on the x-axis instead of the frequency-modulated signal on the y-axis.

The modulated signals obtained in the above steps are sequentially sent to the transmitter 3 (S14), and further sent via the antenna 4 to the base station. FIG. 6 shows an image of the signal p(t) transmitted at this time. In the figure, only the signals related to the outputs of the motion sensors 2a and 2b are shown, and the other signals are omitted. When the signals (A _y , B _y ) related to the y-axis coordinates are transmitted, they are amplitude-modulated according to the sign of the z-axis coordinates.

In this way, by performing amplitude modulation together with frequency modulation in accordance with 1-bit information relating to the sign of the positional information on the z-axis among the sensor outputs, the transmission efficiency of information relating to the attitude of the moving object can be improved. can be enhanced. FIG. 7(a) shows the state of frequency×time resources in a comparative example in which position information on all of the x-axis, y-axis, and z-axis are tentatively transmitted using the batch information gathering method (PhyC-SN). In the figure, each sensor output is transmitted by frequency division, and each coordinate axis is transmitted by time division. A total of 4×3=12 channel resources are required. On the other hand, in the embodiment ((b) in the figure), only the code information of the z-axis coordinate information is superimposed on the y-axis coordinate signal, so that only 4×2=8 channel resources are required. That is, the required frequency×time resources can be reduced to 2/3 compared to the case where the batch information collection method is used as it is.

The reason why the information related to the z-axis coordinates (A _z , B _z , C _z , D _z ) can be reduced to 1-bit code will be described. Fig. 8 shows the initial positions ( _ax , _ay , _az ), ( _bx , _by , _bz ), ( _cx , _cy , _cz ) and (d) of the motion sensors of the automobile (moving body). _x , d _y , d _z ) and the position of each motion sensor (A _x , A _y , A _z ), (B _x , B _y , B _z ), ( Fig. 3 shows simulated graphs for _Cx , _Cy , _Cz ), ( _Dx , _Dy , _Dz );

As shown in FIG. 8, in the case of a mobile body such as an automobile that moves on land, the shaking is almost limited to shaking around the x-axis (rolling), shaking around the y-axis (pitching), or a combination of these. be done. Shaking around the z-axis (rotating shaking around a perpendicular to the bottom surface of the vehicle body) hardly occurs. That is, when each displacement is represented by Euler angles (FIG. 4(c)), in the case of an automobile, etc., the displacement of the vehicle body appears only in β and γ, and α is always 0 or a very small value.

When α=0 or when α can be regarded as a negligibly small amount, the displacement in the z-axis direction can be estimated from the displacement information in the x-axis direction and the y-axis direction. A simple explanatory diagram is shown in FIG. The figure schematically depicts the state of the vehicle body as seen from the z-axis direction when the vehicle body is rotated by β around the y-axis. The figure does not show z-axis coordinate information, but it appears to "shrink" in the x-axis direction as a result of rotation about the y-axis. If this ratio A _x /a _x is known, the Euler angle γ=cos ⁻¹ (A _x /a _x ) around the y-axis can be obtained, and the displacement in the z-axis direction can be estimated as sin(γ).

However, γ can take positive and negative values. That is, in FIG. 9, it cannot be determined from the information in FIG. 9 alone whether the vehicle body is rotated counterclockwise or clockwise. That is, although the absolute value of the z-axis coordinate can be estimated from the values of the x-axis and y-axis coordinates, the sign cannot be estimated. Therefore, the code must be transmitted without fail.

A more detailed description will be given below using mathematical formulas. Although four motion sensors are provided in this embodiment, only the motion sensor 2a will be focused on below. First, the output of the motion sensor 2a on each of the x, y, and z coordinate axes at an arbitrary time is represented by a vector A as shown in Equation (1). Also, the values of each coordinate axis at the initial position are expressed as in Equation (2).

Then, the coordinate vector A and the initial coordinate vector a at an arbitrary time are related as shown in Equation (3).

Here, U, V and W are matrices defined by (3-1), (3-2) and (3-3) below.

γ, β, and α are Euler angles about the x-axis, y-axis, and z-axis, respectively.

Here, if α=0, the matrix W becomes a unit matrix, and equation (3) is as follows.

Therefore, when formula (4) is calculated for each component of x and y, formulas (5) and (6) below are obtained.

Note that a _z = 0 because the bottom surface of the vehicle body in the initial state is the xy plane.

Determining γ and β from equations (5) and (6) yields equations (7) and (8).

By substituting γ and β obtained as described above into the z-component equation (9), an estimated value of the position Az in the z-axis direction can be obtained.

Here, both γ and β can take positive and negative values in both formulas (7) and (8). Therefore, in order to accurately estimate Az from Equation (9), information on the sign of the z-axis coordinate is required. The z-direction positions B _z , C _z , and D _z of the other motion sensors can also be obtained by applying Equation (9) to the respective initial values b _z , c _z , and d _z .

In this embodiment, the value of the z-axis coordinate is calculated by numerical calculation. However, if the calculation is actually performed on the base station side using equations (7) to (9), noise will be mixed in the transmission path. If you do, the calculation results may deviate significantly. Therefore, for example, there is a method of calculating or actually measuring the relationship between the Euler angles α, β, γ and the xyz coordinates (A _x , A _y , A _z ) and tabulating them in advance. Once the x and y coordinate positions are received at the base station side, A _z can be estimated by searching the table for the pair of A _x , A _y that is as close as possible to the measured value (e.g., with the smallest squared error). . At this time, both positive and negative signs of _Az are searched, and one of them may be selected from the sign information sent at the same time.

Examples of the present disclosure will be described below.
(Example 1)
FIG. 10 shows two possible pattern examples calculated when there is no sign information in the z-axis direction. In FIG. 10, the left figure shows the attitude of the moving object when α=0, β=-20°, γ=20°, and the right figure shows the attitude when α=0, β=20°, γ=-20°. shows the posture of the mobile object. When both are viewed from above along the z-axis, they look exactly the same.

(Example 2)
In this example, the recognition accuracy at an arbitrary angle was evaluated by RMSE. The simulation conditions are as follows.

Here, the following formula (10) was used for the calculation of RMSE.

n represents the number of trials, _xi represents Euler angle vectors (including estimated values) recognized by the base station, and X represents true Euler angle vectors (α, β, γ) detected by the motion sensor. In this embodiment, α=0°, β=20°, and γ=-20°. Also, X _max represents the maximum driving angle.

A table is used as the z-axis position information estimation means on the base station side. Obtain the relationship between Euler angles α, β, γ and xyz coordinates (A _x , A _y , A _z ) in increments of 1° in advance, and match the xy-axis position information including noise in consideration of the table and code information. Euler angles α, β, γ and z-axis position information were obtained by

FIG. 11 shows simulation results. Numbers beside the graph are RMSE values for α, β, and γ. It was confirmed that three-dimensional information could be estimated with an error of at most about 3% even at the maximum angle.

INDUSTRIAL APPLICABILITY The present invention can be used, for example, in CASE-compatible automobiles and other means of transportation. In addition, as long as it runs on land, it can be used not only for automobiles, but also for railways and aircraft that use wheels to move on a runway during takeoff and landing.

1 information transmission device 2a, 2b, 2c, 2d motion sensor 3 transmitter 4 antenna
10 processor

Claims (15)

An information transmission device that transmits information related to the attitude of a mobile body having a plurality of wheels,
a group of sensors provided for each of the wheels for measuring and outputting position information in a three-axis coordinate system;
a unit that modulates a carrier with a first physical quantity according to each output related to positional information on the x-axis and positional information on the y-axis among the outputs of the sensor group;
any one of the carriers modulated with the first physical quantity according to at least 1-bit information relating to the code of the positional information on the z-axis among the outputs of the sensor group, a unit that modulates with a second physical quantity different from
a unit for transmitting , in time series, a carrier modulated with the first physical quantity but not modulated with the second physical quantity and a carrier modulated with the first physical quantity and the second physical quantity; An information transmission device with 2. An information transmission apparatus according to claim 1, wherein said moving body is an automobile, and said sensor groups are provided in dampers respectively holding front, rear, left and right wheels. The x-axis is the longitudinal axis of the moving body, the y-axis is the lateral axis of the moving body, and the z-axis is the axis perpendicular to the bottom surface of the moving body. 3. The information transmission device according to claim 1 or 2. 4. The information transmission apparatus according to claim 1, wherein said first physical quantity is the frequency of said carrier. 5. The information transmission apparatus according to claim 1, wherein said second physical quantity is amplitude of said carrier. A mobile body having a plurality of wheels on its body,
a group of sensors provided for each of the wheels for measuring and outputting position information in a three-axis coordinate system;
a unit that modulates a carrier with a first physical quantity according to each output related to positional information on the x-axis and positional information on the y-axis among the outputs of the sensor group;
any one of the carriers modulated with the first physical quantity according to at least 1-bit information relating to the code of the positional information on the z-axis among the outputs of the sensor group, a unit that modulates with a second physical quantity different from
a unit for transmitting , in time series, a carrier modulated with the first physical quantity but not modulated with the second physical quantity and a carrier modulated with the first physical quantity and the second physical quantity; A mobile object with The x-axis is an axis in the longitudinal direction of the vehicle body, the y-axis is an axis in the lateral direction of the vehicle body, and the z-axis is an axis perpendicular to the bottom surface of the vehicle body. The moving body according to claim 6. 8. The moving body according to claim 6, wherein said first physical quantity is the frequency of said carrier. 9. The moving body according to any one of claims 6 to 8, wherein said second physical quantity is the amplitude of said carrier . An information transmission method for transmitting information related to the attitude of a mobile body having a plurality of wheels,
a step of acquiring information from a group of sensors provided for each of the wheels for measuring and outputting position information in a three-axis coordinate system;
a step of modulating a carrier with a first physical quantity according to each output related to positional information on the x-axis and positional information on the y-axis among the outputs of the sensor group;
According to at least 1-bit information relating to the sign of the positional information on the z-axis among the outputs of the sensor group, along with the modulation with the first physical quantity, the carrier is changed to a second physical quantity different from the first physical quantity. and modulating with a physical quantity of . 11. The information transmission method according to claim 10, wherein said first physical quantity is the frequency of said carrier. 12. The information transmission method according to claim 10, wherein said second physical quantity is the amplitude of said carrier. An information transmission program for transmitting information related to the attitude of a mobile body having a plurality of wheels,
a step of acquiring information from a group of sensors provided for each of the wheels for measuring and outputting position information in a three-axis coordinate system;
a step of modulating a carrier with a first physical quantity according to each output related to positional information on the x-axis and positional information on the y-axis among the outputs of the sensor group;
According to at least 1-bit information relating to the sign of the positional information on the z-axis among the outputs of the sensor group, along with the modulation with the first physical quantity, the carrier is changed to a second physical quantity different from the first physical quantity. and modulating the physical quantity of the information transmission program. 14. The information transmission program according to claim 13, wherein said first physical quantity is the frequency of said carrier. 15. The information transmission program according to claim 13, wherein said second physical quantity is the amplitude of said carrier.