Automatic road charging system based only on satellite navigation with guaranteed performance and method for its analysis and design

• US 20070216364A1
• Filed: 01/18/2007
• Published: 09/20/2007
• Est. Priority Date: 01/18/2006
• Status: Active Grant

• Current Assignee: GMV SA
• Original Assignee: GMV Aerospace and Defence, S.A.
• Inventors: Cosmen-Schortmann, Joaquin, Martinez-Olague, Miguel
• Granted Patent: US 7,865,391 B2
• Time in Patent Office: Days
• US Class Current: 320/132
• CPC Class Codes: G07B 15/063 using wireless information transmission between the vehicle and a fixed station identification of vehicles G08G
• CPC Class Codes: G08G 1/20 Monitoring the location of vehicles belonging to a group, e.g. fleet of vehicles, countable or determined number of vehicles

Abstract

The invention relates to an automatic charging system for charging a vehicle (i) for using an infrastructure delimited by a boundary (100) during a charging period Tc based on GNSS location with guaranteed performance, comprising:

• • an onboard receiver wfth integrity guarantee or OBU (30) which, in addition to providing position information, provides additional information relating to the error that can be expected in said position consisting of a health flag (Healthy/Unhealthy), and an RPL or Radial Protection Level, i.e. the amount limiting the horizontal position error according to one direction and with a probability equal to a known value IRX,
  • a detection module (70) determining that the vehicle is within the boundary at a moment when all the delimited points of a region comprised by a circle of radius RPL centered on said position are within the boundary, and
  • a charging module (70) using the result of the detection module to determine that the vehicle has used the infrastructure during said charging period Tc. The invention also relates to a method of analysis and design of such charging system.

Claims

1. An automatic charging system for charging a vehicle (i) for usage of an infrastructure delimited by a boundary (100) during a charging period Tc based on GNSS. location with guaranteed performance, comprising:

an onboard receiver with integrity guarantee or OBU (30) which, in addition to providing position information, provides additional information relating to the error that can be expected in said position, consisting of;

a health flag (Healthy/Unhealthy), when the flag is healthy, the position solution error in any one direction has an upper limit that is the RPL amount with a probability equal to a known value (I_RX), and

an RPL or Radial Protection Level, i.e. the amount delimiting the horizontal position error according to a direction with a probability equal to known value I_RX, i.e.;

P(|{right arrow over (ε

)}·

{right arrow over (u)}|>

RPL)=1−

I_RX

 

where {right arrow over (u)} is any unit vector,

a detection module (70) determining that the vehicle is within the boundary at a moment when all the demarcated points of a region comprised by a circle of radius RPL centered on said position are within the boundary, and

a charging module (70) using the result of the detection module to determine that the vehicle has used the infrastructure during said charging period Tc.

2. An automatic charging system according to claim 1, characterized in that the charging module determines that the vehicle has used the infrastructure during said charging period Tc when there is a predefined number K of positions for which the detection module has determined that the vehicle is within the boundary, i.e. for K positions, a region comprised by a circle of radius RPL centered on them being within the boundary during Tc is complied with,

and wherein the value of K is chosen so as to assure that the probability of mischarging, i.e. the probability that the vehicle carrying the onboard receiver that has not been within the boundary during the charging period is charged, is delimited, the relationship between K and said probability of mischarging being given by the following expression:

3. A system according to claim 1, wherein the onboard receiver or OBU has integrity guarantee due to the implementation of the method and system of assuring integrity disclosed in US patent applications published US 2005/246,093 and/or US 2006/047,413.

4. A system according to claim 1, characterized in that it is an automatic perimetral charging system, the boundary (100) of which is delimited by the points of all the entrance roads to the charging area after which a user of a vehicle is notified that it is subject to charge.

5. A system according to claim 1, characterized in that it is an automatic charging system for road usage, the boundary of which is defined such that it contains said road and does not contain any other road or place allowing the passage or permanence of vehicles.

6. A system according to claim 5, characterized in that it is an automatic charging system for usage of a distance of the road, said distance being calculated on the basis of the sum of lengths of road sections into which the road can be divided such that the only entrance to or exit from each section are the ends thereof.

7. A system according to claim 1, characterized in that in order to charge, the direction of the road on which the vehicle has traveled must be determined by means of checking that at least two positions are available, the sequence of these positions over time defining the circulation direction, and that the regions defined by a circle of radius RPL centered thereon do not intersect.

8. A system according to claim 1, characterized in that the charge depends on the number of times the vehicle has entered the infrastructure.

9. A system according to claim 1, wherein the charge is calculated in the OBU with boundary data sent from a control center.

10. A system according to any claim 1, wherein for different vehicles equipped with OBUs, the charge is calculated in a control center with position data, RPLs and health flags sent from each OBU.

11. A system according to claim 1, characterized in that the OBU includes a module that identifies, for a time equal to the sampling period, the optimal moment in which the sample—

position, speed, RPL and health flag—

is obtained, the optimal moment being that moment the sample of which has a minimal RPL within the set of measurements with health flags declared as healthy, and wherein the value of the sampling period is selected as a value that is;

greater than the sampling period of the receiver,

greater than the measurement correlation time such that it guarantees that the errors of the samples are not correlated, and

less than a given value guaranteeing an overall charging availability level.

12. A method of analysis and design of a perimetral charging system according to claim 1, comprising the following steps:

obtaining a GNSS performance map (D_RX, I_RX, RPL), determining for each point within the boundary and for each sampling moment the probability of having a position tagged as healthy by the receiver (D_Rx=D_Rx({right arrow over (Rr_i)}(t_j^l),t_j^l), as well as the expected RPL values associated to its position measurements for a certain given value of integrity I_RX, according to the performance of the GNSS onboard receiver and GNSS visibility conditions;

obtaining a charging availability map associated to each point within the boundary and sampling moment (p_j), calculating for each point within the boundary and sampling moment the probability that a vehicle located at said point at that moment generates a healthy position sample and that it is detected by the system detection module, so it uses the GNSS performance map together with the following expression of r on each point within the boundary;

p_j=D_Rxj·

r_j

wherein;

D_Rxj=D_Rx({right arrow over (Rr_i)}(t_j^l),t_j^l) is the GNSS position availability (D_RX) at a given point and moment, as it was obtained in the previous step; and

r_j=r_j(z_rj);

is the probability that a circle of radius RPLij centered on {right arrow over (R_mi^H)}(t_j) is within the boundary, this being a function only of the distance from the point to the boundary (z_rj) and of the expected RPL value at the point;

creating a universe of possible trajectories (Tr_i) according to the available real traffic data for the road, each trajectory being defined by a sequence of horizontal position vectors that the vehicle defines on said road and by the frequency of occurrence data thereof (fr_i);

determining the charging availability for each trajectory (Pd_i), determining the charging availability for each trajectory Tr_i by means of a formulation that is a function only of the number of points K that the system charging module requires, of the charging availability at each point of the trajectory, of the decorrelation time of the error of the positions obtained by the GNSS receiver, of GNSS availability, of the length of the trajectory that is within the perimeter and of the speed of the vehicle throughout the trajectory,

determining the average charging availability from Pd_i and the frequency of occurrence of each trajectory fri as;

Charging availability (Average)=Σ

Pd_i·

fr_i

determining the probability of mischarging as;

${\mathrm{Pmd}}_i=\underset{k=K}{\overset{M}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>\left(\begin{array}{c}M\\ k\end{array}\right)<br><br>{\left(1-I_{\mathrm{Rx}}\right)}^k·<br><br>{\left(I_{\mathrm{Rx}}\right)}^{M-k}$

wherein M is the total number of samples that can be generated by the onboard receiver during the entire charging period Tc; and

checking if the road charging system performance is compatible with the existing system performance requirements, and if it is not, checking if it is possible to comply with said requirements by modifying K.

13. A method of analysis and design of a road charging system according to claim 1, and which allows, for a given road section characterized by its geometry, particularly length L and distance d between the edge of the road and the boundary, and the geometry of its surroundings, analyzing the system performance in terms of charging availability and probability of mischarging as a function of the number of positions K required by the charging module, wherein the calculation of the charging availability is done by using a conservative approximation based on the following hypotheses:

the vehicle is always on the road on which vehicles circulate and at the outer edge of the road;

the distance of the latter to the boundary is “

d”

characteristic of the infrastructure and considered constant in the section;

the position errors for probabilities of the order of magnitude of the availability can be conservatively limited by a zero-mean Gaussian distribution with a standard deviation calculated as RPL/F, where F is the factor associated to the probability I_RX of the Gaussian distribution,

where the calculation process is as follows;

the upper allowable limits of the probability of mischarging for a vehicle not using the road Pmd is determined from the number of vehicles that stay off the road Np and from a desired requirement for the probability of mischarging of MD or more vehicles during the charging period Tc (PMD), resolving the following expression by iteration;

$\mathrm{PMD}=\underset{\mathrm{md}=\mathrm{MD}}{\overset{\mathrm{NP}}{\sum <br><br>}}<br><br>\left(\begin{array}{c}\mathrm{Np}\\ \mathrm{md}\end{array}\right)<br><br>{\mathrm{Pmd}}^{\mathrm{md}}·<br><br>{\left(1-\mathrm{Pmd}\right)}^{\mathrm{Np}-\mathrm{md}}$

the number of points K of the system detection module guaranteeing the required Pmd is determined with the obtained Pmd value and given certain integrity (I_Rx) performance of the onboard receiver by means of the following expression;

${\mathrm{Pmd}}_i=\underset{k=K}{\overset{M}{\sum <br><br>}}<br><br>\left(\begin{array}{c}M\\ k\end{array}\right)<br><br>{\left(1-I_{\mathrm{Rx}}\right)}^k·<br><br>{\left(I_{\mathrm{Rx}}\right)}^{M-k}$

a family of curves is constructed with the resulting K value, and given the I_Rx and RPL values for the onboard receiver, and a given signal reception scenario, by means of the following expression of Pdi;

${\mathrm{Pd}}_i\ge <br><br>\left[\underset{k=K}{\overset{m}{\sum <br><br>}}<br><br>\left(\begin{array}{c}m\\ k\end{array}\right)<br><br>{\left(D_{\mathrm{RX}}·<br><br>r\right)}^k·<br><br>{\left(1-D_{\mathrm{RX}}·<br><br>r\right)}^{m-k}\right]$$\mathrm{with}$$r=1-I_{\mathrm{Rx}};<br><br>\left(d=0\right)$$r=P<br><br>\left(N<br><br>\left(0,1\right)<<br><br>F·<br><br>\left(\frac{d}{\mathrm{RPL}}-1\right)\right);<br><br>\left(0<<br><br>d<<br><br>2<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{RPL}\right)$$r=I_{\mathrm{Rx}};<br><br>\left(d\ge <br><br>2<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{RPL}\right)$

the number of points m required for guaranteeing the required charging availability is obtained from said family of curves; and

it is checked that the number of available position samples L/(V·

τ

_c) within the boundary is equal to or greater than the number of necessary samples m resulting from the previous step given a length L of the road section, a speed V of the vehicle and a decorrelation time between measurements τ

_c; and

if this is not the case, it means that it is not possible to simultaneously comply with the probability of mischarging and charging availability requirements for the given scenario for any value of K.

14. A method of analysis and design of a road charging system for roads according to claim 13, which allows applying the same method to identify the road sections complying with certain specified charging availability and probability of mischarging requirements.

15. A method of analysis and design of a road charging system for roads according to claim 13, wherein the RPL value is furthermore modeled as a known function of I_RX according to the features of the receiver, and which allows, for a given road section characterized by its geometry, particularly length L and distance d between the edge of the road and the boundary, and the geometry of its surroundings, and given certain charging availability and probability of mischarging requirements, determining I_RX of the receiver complying with said requirements.