Method and system for estimating the position of a railway vehicle travelling along a railway line, and railway vehicle comprising such system
A method for calculating a location interval of a railway vehicle, including: calculating, at predefined and successive times: maximum and minimum positions reached by the vehicle as points on a digital map based on signals indicative of the absolute position of the vehicle; maximum and minimum distances travelled by the vehicle with respect to a reference point based on odometry; at a selected time adding: to the maximum and minimum positions at a time earlier than the selected time, the difference between values of the maximum distance at the selected and at the earlier times and the difference between values of the minimum distance at the selected and at the earlier times, thereby determining reference first maximum position and second minimum position. The advanced end of the interval is the most forward position between the first reference maximum position and the value of the maximum position at the selected time.
1 . A method for calculating, substantially in real time, an interval within which at least a reference part of a railway vehicle which is travelling along a railway line is located, the railway vehicle comprising a controller positioned in the railway vehicle, the method, via the controller, comprising:
calculating, at predefined and successive instants of time:
a maximum position and a minimum position reached by the railway vehicle both calculated as points on a digital map and based on first signals which are provided by a receiver mounted onboard the railway vehicle and are indicative of a current absolute position of the railway vehicle; and
a maximum distance and a minimum distance travelled by the railway vehicle with respect to a reference position, the maximum distance and the minimum distance being calculated based on second signals provided by an onboard odometry system of the railway vehicle;
at a selected instant of time of the predefined and successive instants of time, adding:
to the maximum position calculated at an instant of time earlier than the selected instant of time, a difference between a value of the maximum distance calculated at the selected instant of time and a value of the maximum distance calculated at the instant of time earlier than the selected instant of time, thereby determining on the digital map a first reference maximum position; and
to the minimum position calculated at the instant of time earlier than the selected instant of time, a difference between a value of the minimum distance calculated at the selected instant of time and a value of the minimum distance calculated at the instant of time earlier than the selected instant of time, thereby determining on the digital map a second reference minimum position; and
calculating the interval within which at least the reference part of the railway vehicle is located, by assigning:
as its most advanced end or upper end, a most forward position between a position calculated for the first reference maximum position and a value of the maximum position calculated at the selected instant of time; and
as its rearmost end or lower end, a most rearward position between a position calculated for the second reference minimum position and a value of the minimum position calculated at the selected instant of time.
2 . The method of claim 1 , wherein the selected instant of time is selected with respect to the instant of time earlier than the selected instant of time based on when at least one of the following criteria is satisfied:
at least a predefined time interval has elapsed between the selected instant of time and the instant of time earlier than the selected instant of time; or
the railway vehicle has travelled at least a predefined distance along the railway line with reference to its position at the instant of time earlier than the selected instant of time.
3 . The method of claim 2 , wherein the predefined time interval is comprised between 1 and 30 seconds.
4 . The method of claim 3 , wherein the predefined time interval is about 10 seconds.
5 . The method of claim 2 , wherein the predefined distance is comprised between 10m and 150m.
6 . The method of claim 5 , wherein the predefined distance is about 100m.
7 . The method of claim 1 , wherein the reference position is a starting point of a travel of the railway vehicle or a last group of balises laid down along the railway line or another element of the railway line taken as a reference.
8 . A system for calculating, substantially in real time, an interval within which at least a reference part of a railway vehicle which is travelling along a railway line is located, comprising:
a controller positioned onboard the railway vehicle;
at least one digital map associated with or comprised in the controller;
a receiver mounted onboard the railway vehicle, the receiver being arranged to provide to the controller first signals indicative of a current absolute position of the railway vehicle; and
an onboard odometry system which is arranged to provide to the controller second signals indicative of an actual distance travelled by the railway vehicle along the railway line with respect to a reference point;
wherein the controller:
calculates at each instant time of a plurality of successive instants of time:
a maximum position and a minimum position both calculated as points on the digital map, the maximum position and the minimum position being calculated based on the first signals provided by the receiver; and
a maximum distance and a minimum distance travelled by the railway vehicle with respect to the reference point, the maximum distance and minimum distance being calculated based on the second signals provided by the onboard odometry system of the railway vehicle;
at a selected instant of time of the plurality of successive instants of time, adds:
to the maximum position calculated at an instant of time earlier than the selected instant of time, a difference between a value of the maximum distance calculated at the selected instant of time and a value of the maximum distance calculated at the instant of time earlier than the selected instant of time, thereby determining on the digital map a first reference maximum position; and
to the minimum position calculated at the instant of time earlier than the selected instant of time, a difference between a value of the minimum distance calculated at the selected instant of time and a value of the minimum distance calculated at the instant of time earlier than the selected instant of time, thereby determining on the digital map a second reference minimum position; and
calculates the interval within which at least the reference part of the railway vehicle is located, by assigning:
as its most advanced end or upper end, a most forward position between the position calculated for the first reference maximum position and a value of the maximum position calculated at the selected instant of time; and
as its rearmost end or lower end, a most rearward position between the position calculated for the second reference minimum position and a value of the minimum position calculated at the selected instant of time.
9 . The system of claim 8 , wherein the controller is further configured to select the selected instant of time with respect to the instant of time earlier than the selected instant of time based on when at least one of the following criteria is satisfied:
at least a predefined time interval has elapsed between the selected instant of time and the instant of time earlier than the selected instant of time; or
the railway vehicle has travelled at least a predefined distance along the railway line with reference to its position at the instant of time earlier than the selected instant of time.
10 . The system of claim 8 , wherein the receiver is configured to receive from a satellite system or from a 5G communications network signals indicative of the current absolute position of the railway vehicle.
11 . A railway vehicle comprising the system of claim 8 .
12 . The method of claim 1 , wherein the calculation of the interval is performed according to a railway safety standard protocol to control the railway vehicle.
13 . The method of claim 12 , wherein the railway safety standard protocol meets safety integrity level defined for railway signaling and control system by CENELEC EN 50129.
14 . The method of claim 12 , wherein the railway safety standard protocol meets a safety Integrity Level 4 (SIL4).
15 . The method of claim 12 , wherein the railway safety standard protocol has a probability of a single error in 10,000 years.
16 . The system of claim 9 , wherein the predefined time interval is comprised between 1 and 10 seconds.
17 . The system of claim 16 , wherein the predefined time interval is comprised between 1 and 3 seconds.
18 . The system of claim 8 , wherein the calculation of the interval is performed according to a railway safety standard protocol to control the railway vehicle.
19 . The system of claim 18 , wherein the railway safety standard protocol meets safety integrity level defined for railway signaling and control system by CENELEC EN 50129.
20 . The system of claim 18 , wherein the railway safety standard protocol meets a safety Integrity Level 4 (SIL4).