Information processing device, information processing method, and non-transitory computer readable medium

1 . An information processing device, comprising a computer processor configured to:

acquire a measurement value which has been measured by a sensor provided in a vehicle while the vehicle is traveling on a road surface;

calculate a vibration feature quantity P v (t) based on expressions below from acceleration values for respective X, y, and Z components, the acceleration values being included in the measurement value which has been acquired,

Pv(t)=. . . where N FFT is the number of taps of Fast Fourier Transform (FFT), p(fi) 2 =px(fi) 2 +py(fi) 2 +pz(fi) 2

where px(fi), py(fi), and pz(fi) are power values in a frequency band fi which have been obtained by FFT from the acceleration values for the respective x, y, and z components, and

f 0 to f n_m are a DC component and a near frequency band thereof;

calculates a road vibration coefficient ρ based on the vibration feature quantity P v (t) which has been calculated and an expression below,

P v (t)=ρ·v(t) 2 where v(t) is a velocity of the vehicle, and ρ is a road vibration coefficient which is a parameter indicating a relationship between the road surface and the vehicle;

wherein f 0 to f n_m corresponds to a DC component when i=0 and a near band frequency of the DC component when i=1 to n_m;

identify a movement distance for each time Δt in which the measurement value is obtained,

determine, for a movement locus which is identified from the movement distance and a movement direction estimated for each unit time Δt, a movement path in a traveling site of the vehicle by determining an initial position and an initial orientation as initial conditions in a coordinate system of a traveling site where the vehicle has traveled,

the vehicle being provided with a receiver that receives radio signals from one or more transmitters disposed in the traveling site,

acquire a reception record which is output from the receiver, the reception record including a transmitter ID for identifying a transmission source, reception date and time information indicating a date and time at which the radio signal was received, and received signal strength (RSSI) indicating signal strength at the reception,

identify, based on the reception date and time information, a reception position at which the receiver received the radio signal from the transmitter on the movement locus, and

identify, as the initial conditions, an initial orientation Θ, an initial position X I in an x-direction in the coordinate system of the traveling site, and an initial position Y I in a y-direction in the coordinate system such that a cost is minimum, which is obtained from a distance (d) from a position of the transmitter to the reception position in the coordinate system of the traveling site and RSSI at the reception position.

2 . The information processing device as set forth in claim 1 , wherein the computer processor is further configured to:

identify the movement distance for each unit time Δt by estimating, for each unit time Δt in which the measurement value is obtained, a movement velocity vf and an acceleration a f along an x-direction of the vehicle with use of a Kalman filter,

in a prediction step of the Kalman filter, obtains prediction values of a movement velocity v ft and an acceleration art at a time point t of interest based on a movement velocity v ft-1 and an acceleration a ft-1 which have been estimated at a time point t−1 which precedes the time point t of interest by the unit time Δt,

in an updating step of the Kalman filter, (i) obtain an observation error covariance matrix below based on the vibration feature quantity Pv(t) and an acceleration αf(t) which have been observed at the time point t of interest,

H=. . .

(ii) modify, based on the observation error covariance matrix, the prediction values which have been predicted in the prediction step, and thus (iii) obtain estimation values of the movement velocity vit and the acceleration art at the time point t of interest.

3 . The information processing device as set forth in claim 2 , wherein the computer processor is further configured to:

acquire a rotation amount around a z-axis for each unit time Δt based on an angular velocity value of the z-axis which has been measured by the sensor for each unit time Δt; and

estimate the movement distance and the movement direction until a time point t+1 which is after the time point t of interest by the unit time Δt based on the estimation values of the movement velocity vft and the acceleration aft and the rotation amount around the z-axis at the time point t of interest.

4 . The information processing device as set forth in claim 1 , wherein the computer processor: generates the map data of the traveling site by plotting the movement locus as a definitive movement path in the coordinate system of the traveling site based on the initial position X I in the x-direction, the initial position Y I in the y-direction, and the initial orientation Θ which have been identified.

5 . An information processing device, comprising a computer processor configured to:

acquire a measurement value which has been measured by a sensor provided in a vehicle while the vehicle is traveling on a road surface;

calculate a vibration feature quantity P v (t) based on expressions below from acceleration values for respective X, y, and Z components, the acceleration values being included in the measurement value which has been acquired,

Pv(t)=. . . where N FFT is the number of taps of Fast Fourier Transform (FFT), p(fi) 2 =px(fi) 2 +py(fi) 2 +pz(fi) 2

where px(fi), py(fi), and pz(fi) are power values in a frequency band fi which have been obtained by FFT from the acceleration values for the respective x, y, and z components, and

f 0 to f n_m are a DC component and a near frequency band thereof;

calculates v(t) based on the vibration feature quantity P v (t) which has been calculated, an expression below, and a road vibration coefficient ρ which has been set in advance,

P v (t)=ρ·v(t) 2 where v(t) is a velocity of the vehicle, and ρ is a road vibration coefficient which is a parameter indicating a relationship between the road surface and the vehicle

wherein f 0 to f n_m corresponds to a DC component when i=0 and a near band frequency of the DC component when i=1 to n_m;

identify a movement distance for each time Δt in which the measurement value is obtained,

determine, for a movement locus which is identified from the movement distance and a movement direction estimated for each unit time Δt, a movement path in a traveling site of the vehicle by determining an initial position and an initial orientation as initial conditions in a coordinate system of a traveling site where the vehicle has traveled,

the vehicle being provided with a receiver that receives radio signals from one or more transmitters disposed in the traveling site,

acquire a reception record which is output from the receiver, the reception record including a transmitter ID for identifying a transmission source, reception date and time information indicating a date and time at which the radio signal was received, and received signal strength (RSSI) indicating signal strength at the reception,

identify, based on the reception date and time information, a reception position at which the receiver received the radio signal from the transmitter on the movement locus, and

identify, as the initial conditions, an initial orientation Θ, an initial position X I in an x-direction in the coordinate system of the traveling site, and an initial position Y I in a y-direction in the coordinate system such that a cost is minimum, which is obtained from a distance (d) from a position of the transmitter to the reception position in the coordinate system of the traveling site and RSSI at the reception position.

6 . An information processing method performing using a computer processor, the method comprising:

an acquisition step of acquiring with the computer processor a measurement value which has been measured by a sensor provided in a vehicle while the vehicle is traveling on a road surface;

a vibration feature quantity calculation step of calculating with the computer processor a vibration feature quantity Pv(t) based on expressions below from acceleration values for respective x, y, and z components, the acceleration values being included in the measurement value which has been acquired,

Pv(t)=. . . where N FFT is the number of taps of Fast Fourier Transform (FFT), p(fi) 2 =px(fi) 2 +py(fi) 2 +pz(fi) 2

where px(fi), py(fi), and pz(fi) are power values in a frequency band fi which have been obtained by FFT from the acceleration values for the respective x, y, and z components, and

f 0 to f n_m are a DC component and a near frequency band thereof;

a road vibration coefficient calculates step of calculating with the computer processor a road vibration coefficient ρ based on the vibration feature quantity P v (t) which has been calculated and an expression below,

P v (t)=ρ·v(t) 2 where v(t) is a velocity of the vehicle, and ρ is a road vibration coefficient which is a parameter indicating a relationship between the road surface and the vehicle;

wherein f 0 to f n_m corresponds to a DC component when i=0 and a near band frequency of the DC component when i=1 to n_m;

identify a movement distance for each time Δt in which the measurement value is obtained,

determine, for a movement locus which is identified from the movement distance and a movement direction estimated for each unit time Δt, a movement path in a traveling site of the vehicle by determining an initial position and an initial orientation as initial conditions in a coordinate system of a traveling site where the vehicle has traveled,

the vehicle being provided with a receiver that receives radio signals from one or more transmitters disposed in the traveling site,

acquire a reception record which is output from the receiver, the reception record including a transmitter ID for identifying a transmission source, reception date and time information indicating a date and time at which the radio signal was received, and received signal strength (RSSI) indicating signal strength at the reception,

identify, based on the reception date and time information, a reception position at which the receiver received the radio signal from the transmitter on the movement locus, and

identify, as the initial conditions, an initial orientation Θ, an initial position X I in an x-direction in the coordinate system of the traveling site, and an initial position Y I in a y-direction in the coordinate system such that a cost is minimum, which is obtained from a distance (d) from a position of the transmitter to the reception position in the coordinate system of the traveling site and RSSI at the reception position.

7 . An information processing method performing using a computer processor, the method comprising:

an acquisition step of acquiring with the computer processor a measurement value which has been measured by a sensor provided in a vehicle while the vehicle is traveling on a road surface;

a vibration feature quantity calculation step of calculating with the computer processor a vibration feature quantity Pv(t) based on expressions below from acceleration values for respective x, y, and z components, the acceleration values being included in the measurement value which has been acquired,

Pv(t)=. . . where N FFT is the number of taps of Fast Fourier Transform (FFT), p(fi) 2 =px(fi) 2 +py(fi) 2 +pz(fi) 2

where px(fi), py(fi), and pz(fi) are power values in a frequency band fi which have been obtained by FFT from the acceleration values for the respective x, y, and z components, and

f 0 to f n_m are a DC component and a near frequency band thereof;

a movement velocity calculation step of calculating with the computer processor v(t) based on the vibration feature quantity P v (t) which has been calculated and an expression below, and a road vibration coefficient ρ which has been set in advance,

P v (t)=ρ·v(t) 2 where v(t) is a velocity of the vehicle, and ρ is a road vibration coefficient which is a parameter indicating a relationship between the road surface and the vehicle;

wherein f 0 to f n_m corresponds to a DC component when i=0 and a near band frequency of the DC component when i=1 to n_m;

identify a movement distance for each time Δt in which the measurement value is obtained,

determine, for a movement locus which is identified from the movement distance and a movement direction estimated for each unit time Δt, a movement path in a traveling site of the vehicle by determining an initial position and an initial orientation as initial conditions in a coordinate system of a traveling site where the vehicle has traveled,

the vehicle being provided with a receiver that receives radio signals from one or more transmitters disposed in the traveling site,

acquire a reception record which is output from the receiver, the reception record including a transmitter ID for identifying a transmission source, reception date and time information indicating a date and time at which the radio signal was received, and received signal strength (RSSI) indicating signal strength at the reception,

identify, based on the reception date and time information, a reception position at which the receiver received the radio signal from the transmitter on the movement locus, and

identify, as the initial conditions, an initial orientation Θ, an initial position X I in an x-direction in the coordinate system of the traveling site, and an initial position Y I in a y-direction in the coordinate system such that a cost is minimum, which is obtained from a distance (d) from a position of the transmitter to the reception position in the coordinate system of the traveling site and RSSI at the reception position.

8 . A non-transitory computer readable medium that stores a control program, wherein the control program causes a computer to function as an information processing device recited in claim 1 .

9 . A non-transitory computer readable medium that stores a control program, wherein the control program causes a computer to function as an information processing device recited in claim 5 .