Method of performing a self-calibrating rolling brake test on a rail vehicle

Abstract

A data processing system 10 receives an input set of rail vehicle characteristics, e.g. train weight, gauge and wheel profile received from data storage 16 or Driver Machine Input 18. It also receives

Description

The present invention relates to a computer-implemented method of performing a self-calibrating rolling brake test on a rail vehicle. Typically, a train driver of an ETCS fitted train performs a Start of Mission procedure in order to allow the train to start its movement along the track, according to the planned operative modes and the ERTMS / ETCS level. In this procedure, the train driver enters and / or confirms the following sets of data: train data, and additional data. Train data refer to rolling stock characteristics and include: train running number, maximum train speed, ERTMS train category, train length, deceleration data, power supply, loading gauge, axle load, train fitted with airtight system, list of NTC (National Train Control) modules available. Additional data refer to other parameters that may be needed to perform the mission and include: Driver ID, ERTMS / ETCS Level, RBC (Radio Block Centre) identification / telephone number, adhesion factor, and, if required by the journey, the STM to be activated including additional STM data. Such data is entered via a Driver Machine Interface (DMI), which is the interface between the driver and the onboard equipment, and is typically located on the driver's desk. The DMI can have a display screen that may be touch-sensitive and / or have buttons to permit the driver to input data, request permission to move and acknowledge certain events. One reason for requiring such detailed rail vehicle information is to enable the rail vehicle speed and braking curves to be calculated. Clearly, therefore, any inconsistencies or errors in the input of this information can have very serious consequences for rail vehicle safety. For example, a train may end up operating at an unsafe speed or braking curve should the information indicate better performance than the rail vehicle is capable of. Alternatively, a train may have its speed restricted unnecessarily should any errors in the driver input result in lower speeds and braking curves being calculated. This results in less efficient use of the railway network. The theoretical braking performance of rolling stock can vary significantly due to the many factors which affect how a vehicle decelerates. For modern fixed formation multiple train units, the information needed to calculate the train speed and braking profiles is often inherent in the formation, since this is fixed and does not vary between routes or journeys. Therefore, no information is input by the driver, who merely confirms the data is correct, thus reducing the likelihood of incorrect speed and braking calculations. Nevertheless, this inherent data may still vary from the actual performance of the train. However, for non-fixed formation trains, such as for locomotive hauled coaching stock or freight trains, the rail vehicle information input is essential. The more varied and longer the train formulation, the more likely it is that an error will occur during the input of the rail vehicle information. At the time of filing, there is no known method of proving that the information has been entered into the DMI correctly, meaning that such errors in inputting rail vehicle information would routinely go undetected. Even when such rail vehicle information is entered into the DMI correctly, it is not possible to know whether the rail vehicle will perform to their required standards, whether they are maintained correctly or have been loaded correctly (for example, by being either overweight or out of gauge). One manner in which these issues may be dealt with is to provide the on-board equipment with the ability to use either conservative parameters in calculations, or to provide a tolerance in the expected data values, in order to take into account the probability of an error in data entry to the DMI. However, whilst this deals with errors to a certain extent, it does not deal with safety or infrastructure utilisation issues. The present invention aims to address these issues, by providing, in a first instance, a computer-implemented method of performing a self-calibrating rolling brake test on a rail vehicle, comprising: receiving an input set of rail vehicle characteristics; receiving a set of independently verified rail vehicle characteristics; calibrating the input set of rail vehicle characteristics using the set of independently verified rail vehicle characteristics to produce a calibrated set of rail vehicle characteristics; on the basis of the calibrated set of rail vehicle characteristics, controlling the rail vehicle to perform a rolling brake test; and comparing the actual braking performance of the rolling brake test to an expected braking performance and outputting a recommendation for rail vehicle operation based on the comparison. By calibrating an input set of rail vehicle characteristics based on independently verified values even if errors are included in the input of the rail vehicle characteristics these errors are negated in calculations without the need to use parameter ranges or error tolerance. Such calculations resulting in the output of a recommended rail vehicle operation ensure that the most appropriate operation conditions are used in each journey on each route by each rail vehicle. The input rail vehicle characteristics may be received by accessing a data storage device in the rail vehicle. Alternatively, the input rail vehicle characteristics may be received from a data input device and input by a user. Preferably, the independently verified rail vehicle characteristics are received from a trackside system. Preferably, the method further comprises obtaining the expected braking performance from one of: an accessible memory in the rail vehicle and a remote server. Preferably, controlling the rail vehicle to perform a rolling brake test comprises: determining a suitable location for the rolling brake test to be carried out; monitoring the geographical location of the rail vehicle; at the point the geographical location of the rail vehicle matches the suitable location for the rolling brake test, applying the brakes of the rail vehicle to bring the rail vehicle to rest or to a pre-determined reduced speed based on the calibrated set of vehicle characteristics; and monitoring the performance of the rail vehicle during the rolling brake test. Preferably, the method is performed on a processor on board the rail vehicle. Preferably, outputting a recommendation for rail vehicle operation comprises one of: a) if the actual braking performance during the rolling brake test matches the expected braking performance during a rolling brake test, displaying an indication to a user that no changes to the rail vehicle operation are recommended; b) if the actual braking performance during the rolling brake test is better than the expected braking performance during a rolling brake test, displaying an indication to a user that changes to improve rail vehicle speed and braking curve are recommended; or c) if the actual braking performance during the rolling brake test is worse than the expected braking performance during a rolling brake test, displaying an indication to a user that changes to reduce rail vehicle speed and braking curve will be enforced. If reduced rail vehicle speed and braking curve are enforced, the rail vehicle may also be halted immediately. In a second instance, the present invention also provides a data-processing system adapted to perform a self-calibrating rolling brake test on a rail vehicle, comprising: a processor adapted to receive an input set of rail vehicle characteristics; receive a set of independently verified rail vehicle characteristics; calibrate the input set of rail vehicle characteristics using the set of independently verified rail vehicle characteristics to produce a calibrated set of rail vehicle characteristics; on the basis of the calibrated set of rail vehicle characteristics, control the rail vehicle to perform a rolling brake test; and compare the actual braking performance of the rolling brake test to the expected braking performance and output a recommendation for rail vehicle operation based on the comparison; a receiver adapted to receive the set of independently verified rail vehicle characteristics and to communicate the set of independently verified rail vehicle characteristics to the processor; a location device adapted to determine the geographical location of the rail vehicle and to provide this to the processor; an accessible memory device adapted to store details of suitable locations for rolling brake testing and accessible by the processor; and a display device adapted to display the recommendation for rail vehicle operation, wherein the processor, receiver, location device, accessible memory device and display device are connected via a data bus. Preferably, the data-processing system further comprises a user input device adapted to receive the input set of rail vehicle characteristics from a user, the user input device also being connected to the data bus. Preferably, the input set of rail vehicle characteristics are stored in the accessible memory device. In a further instance, the present invention also provides a rail vehicle comprising the data-processing system outlined above. Preferably, the rail vehicle is a train. The invention will now be described by way of example only, and with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of a data-processing system useful for carrying out methods in accordance with embodiments of the present invention; and Figure 2 is a flowchart illustrating the steps of a method in accordance with an embodiment of the present invention. Rather than using adjustments based on the data input by a train driver to a DMI, a computer-implemented method of performing a self-calibrating rolling brake test on a rail vehicle may be used to determine a safe speed and braking curve for a rail vehicle. Initially, a set of expected rail vehicle characteristics is received. This may be data input via the DMI, or may be accessed from an accessible memory for rail vehicles with fixed formations. Next, a set of independently verified rail vehicle characteristics is received, which do not require any input or confirmation from a driver. The expected set of rail vehicle characteristics is then calibrated using the set of independently verified rail vehicle characteristics to produce a calibrated set of rail vehicle characteristics. These are then used to control the rail vehicle to perform a rolling brake test, with the actual braking performance of the rolling brake test compared to an expected braking performance and a recommendation for rail vehicle operation output based on the comparison. A data-processing system is provided as part of the on-board equipment to be able to carry out the method, as described in more detail below. The embodiments of the present invention are described in relation to the European Rail Traffic Management System (ERTMS), which is a signalling and traffic management system. However, they may also be carried out in conjunction with a Communication-Based Train Control (CBTC) system, or other train borne system. ERTMS has two main components: the ETCS and GSM-R (Global System for Mobile Communications - Railway). ETCS includes both trackside and on-board sub-systems. The track-side sub-system typically comprises the following elements: a Transparent Eurobalise (a transmission device that sends telegrams to the on-board sub-system); a Fixed Eurobalise (a transmission device that sends telegrams to the on-board sub-system based on pre-defined telegrams that are transmitted to every train); a Lineside Electronic Unit (LEU) (an electronic device that generates telegrams to be sent by a Eurobalise, based on information received from external track-side systems); Euroloop and Radio infill, which provide signalling information in advance; and Radio Block Centre (RBC) (a computer-based system that elaborates messages to be sent to the rail vehicle, based on information received from external track-side sub-systems and information exchanged with the on-board sub-systems using GSM-R). The on-board sub-system comprises on-board equipment responsible for supervising the movement of the train to which it belongs, on the basis of information exchanged with track-side sub-system by means of a Balise Transmission Unit (BTU) and / or Radio Transmission Unit (RTM), and possibly the on-board part of the GSM-R radio system according to the particular ETCS level. In particular, a European Vital Computer (EVC) is responsible for safety critical functions and is the unit with which many other train functions interact, including for example the odometer. The Driver Machine Interface (DMI) is the interface between the driver and the on-board equipment, and is typically located on the driver's desk. The DMI preferably has a display screen that may be touch-sensitive and / or have buttons to permit the driver to input data, request permission to move and acknowledge certain events. ATrain Interface Unit (TIU) provides the interface between the on-board equipment and other systems of the train such as the brake interface. A Juridical Recorder Unit provides 'black box' functions, storing the most important data and variables from train journeys to allow later analysis. Figure 1 is a schematic diagram of a data-processing system useful for carrying out methods in accordance with embodiments of the present invention. The data-processing system 10 comprises elements within the ERTMS system outlined above. A processor 11 is provided, which in this is example is in an ERTMS set up and preferably sits within a European Vital Computer (EVC) 12. A radio transmission unit (RTM) 13 acts as a receiver to enable communication of independently verified rail vehicle characteristics to the processor 11, and sits within a GSM-R radio system 14. A location device 15 is adapted to determine the geographical location of the rail vehicle and to provide this to the processor. The location device 15 may be a GSM (Global System for Mobile Communications) device hosted within the GSM-R radio system 14, or a separate GPS (Global Positioning System) device. An accessible memory device 16 is adapted to store details of suitable locations for rolling brake testing and accessible by the processor 11. This again forms part of an EVC 12 in this example. A display device 17 is provided and adapted to display the recommendation for rail vehicle operation, which in this example forms part of a Driver Machine Interface (DMI) 18. The processor 11, receiver 13, location device 15, accessible memory device 16 and display device 17 are connected via a data bus 19, to allow data communication between each of the elements of the data-processing system 10. The DMI 18 is also provided with a user input device 20 adapted to receive the input set of rail vehicle characteristics from a user. Since the user input device 20 is part of the DMI 18, the user input device 20 is also connected to the data bus 19. The processor 11 is adapted to receive an input set of rail vehicle characteristics from either the accessible memory device 16 or from a user via the DMI 18, as well as to receive a set of independently verified rail vehicle characteristics, typically via the radio transmission unit 13 from the RBC or via a Balise Transmission Unit (BTU) 21. The processor 11 is also adapted to calibrate the input set of rail vehicle characteristics using the set of independently verified rail vehicle characteristics to produce a calibrated set of rail vehicle characteristics. The processor 11 communicates with a Train Interface Unit (TIU) 22 to control the rail vehicle to perform a rolling brake test based on the calibrated set of rail vehicle characteristics. A rolling brake test differs from a static brake test in that a rolling brake test measures braking performance whereas a static brake test measures the holding capacity of the brakes when the rail vehicle is at a standstill. The actual braking performance of the rolling brake test is compared to the expected braking performance by the processor 11, as described in more detail below, and a recommendation for rail vehicle operation based on the comparison is output, in this example, to a train driver via the DMI 18. Figure 2 is a flowchart illustrating the steps of a method in accordance with an embodiment of the present invention. The computer-implemented method 200 begins at step 202 with the processor 11 receiving an input set of rail vehicle characteristics, which contain at least the weight and gauge of the rail vehicle as well as wheel profiles. At step 204, the processor 11 receives a set of independently verified rail vehicle characteristics. These are obtained from a trackside system that is capable of measuring the weight and gauge of a rail vehicle as well as information regarding the profile of the wheels and retrieving data from the RBC. For example, a Weight-in-Motion (WIM) system may be used, comprising an axle weight sensor mounted on each rail of a railway track to measure the relative weight of each wheel of the rail vehicle as it travels along the railway track. A LiDAR scanning system may be used to determine the gauge of the rail vehicle. A wheel impact load detector (commonly referred to as "WILD"), such as a strain gauge system attached to each rail is used to measure the impact each wheel has on the rail in passing. This produces a load profile for each wheel, which is then used to determine the wheel condition. In addition, data is retrieved from the RBC relating to nominal wheel radius, brake type, and contact pressure for the brakes. At step 206 the processor calibrates the input set of rail vehicle characteristics using the set of independently verified rail vehicle characteristics to produce a calibrated set of rail vehicle characteristics. At step 208, on the basis of the calibrated set of rail vehicle characteristics, the processor 11 controls the rail vehicle to perform a rolling brake test. This is done via the train interface unit 22 and the rail vehicle braking system, and involves determining a suitable location for the rolling brake test to be carried out, which is preferably based on map and route information available either from information stored in the accessible memory device 16 or from the RBC via the GSM-R. The geographical location of the rail vehicle is monitored, using the location device 15, and at the point the geographical location of the rail vehicle matches the suitable location for the rolling brake test, the brakes of the rail vehicle are applied in order to bring the rail vehicle to rest or to a pre-determined reduced speed. The performance of the rail vehicle during the rolling brake test is monitored by the processor 11, for example, by monitoring the deceleration via the odometer and a timer and noting the start and end locations of the rolling brake test. Finally, at step 210, the processor 11 compares the actual braking performance of the rolling brake test to an expected braking performance and outputs a recommendation for rail vehicle operation based on the comparison. This recommendation is preferably output via the DMI 18. The set of calibrated rail vehicle characteristics is used to calculate the stopping distance 5 required to bring the rail vehicle to a halt. As laid out in the standard UIC 544-1, the braking distance of a rail vehicle can be calculated in steps using the equation: £ Ft + Wf = me x at Equation 1 where IF is the sum of the deceleration forces of all brakes on the rail vehicle at a time i, Wi is the resistance to forwards movement at time i, me is the equivalent mass of the rail vehicle and a, is the deceleration at time i. Using one of the five basic equations of motion, for a calculation time interval At (where At <1 second) the speed v, at the start of the time interval and the speed vt+i at the end of the time interval is given by: vi+1 =vt- (at x At) Equation 2 Given that the mean speed vmi in the time interval At is the average of v, and vi+i, and the distance AS covered in the time interval At is: AS) = vmi x At Equation 3 Hence the total stopping distance is given by the sum of AS, over time. Since the set of calibrated rail vehicle characteristics contains a calibrated weight of the rail vehicle, a calibrated wheel radius, and braking system details, the processor 11 is able to calculate a stopping distance 5 for the rail vehicle. This stopping distance also represents the optimum braking curve for the rail vehicle. For a rolling brake test where the rail vehicle is brought to a pre-determined reduced speed the braking rate may be calculated from the amount of time the rail vehicle takes to reach the pre-determined reduced speed and the distance travelled until the pre-determined reduced speed is reached. For example, for a train travelling at 40mph, the pre-determined reduced speed may be set at 30mph as the rolling brake test. Once the processor 11 has calculated the stopping distance 5, the rolling brake test can be carried out at the point the rail vehicle reaches the suitable location. The start and end locations of the rolling brake test are recorded by the processor 11, and the actual braking distance determined from the distance between the point the brake command was issued at the start of the rolling brake test to the point the rail vehicle came to a complete halt. The actual braking distance is then compared to an expected braking performance based upon the formation of the rail vehicle, the braked weight of the carriages forming the rail vehicle and the methodology laid out in the UCI 544-1 standard. The comparison then enables the recommendation for rail vehicle operation to be output, which is determined as follows. If the actual braking performance during the rolling brake test matches the expected braking performance during a rolling brake test, an indication is displayed to the driver via the DMI 18 that no changes to the rail vehicle operation are recommended. If the actual braking performance during the rolling brake test is better than the expected braking performance during a rolling brake test, an indication is displayed to the driver via the DMI 18 that changes to improve rail vehicle speed and braking curve are recommended. If the actual braking performance during the rolling brake test is worse than the expected braking performance during a rolling brake test, an indication is displayed to the driver via the DMI 18 that changes to reduce rail vehicle speed and braking curve will be enforced. If the actual braking performance is particularly poor, then the rail vehicle is halted immediately and does not proceed any further. The calibration process takes into account not only the independently verified rail vehicle characteristics, but any corrections that need to be made in order to calculate the stopping distance 5 based upon the UIC 544-1 standard. For example, in calibrating the weight of the rail vehicle it is necessary not only to take into account the weight measured by the trackside system, but to include a correction for rotating masses, such as the wheels, cog wheels and motor rotors, since these create an apparent increase in weight during acceleration and deceleration. The measured weight may either be corrected by a set value per carriage in the rail vehicle formation, or multiplied by a correction factor The wheel profiles obtained give details of not just the wheel radius, but also issues that could affect the wheel-rail contact, such as flat spots. Hence the set of calibrated rail vehicle characteristics represents the most accurate set of real-world data for a particular rail vehicle on a specific route. This leads to recommendations for rail vehicle operating parameters that are the optimum in terms of balancing both safety and rail infrastructure use. Preferably, in the examples and embodiments outlined above, the rail vehicle is a train. These and other advantages of the embodiments of the present invention falling within the scope of the appended claims will be apparent to the person skilled in the art.

Claims

1. A computer-implemented method of performing a self-calibrating rolling brake test on a rail vehicle, comprising:receiving an input set of rail vehicle characteristics;receiving a set of independently verified rail vehicle characteristics;calibrating the input set of rail vehicle characteristics using the set of independently verified rail vehicle characteristics to produce a calibrated set of rail vehicle characteristics;on the basis of the calibrated set of rail vehicle characteristics, controlling the rail vehicle to perform a rolling brake test; andcomparing the actual braking performance of the rolling brake test to an expected braking performance and outputting a recommendation for rail vehicle operation based on the comparison.

2. Method as claimed in claim 1, wherein the input rail vehicle characteristics are received by accessing a data storage device in the rail vehicle.

3. Method as claimed in claim 1, wherein the input rail vehicle characteristics are received from a data input device and input by a user.

4. Method as claimed in any of claims 1 to 3, wherein the independently verified rail vehicle characteristics are received from a trackside system.

5. Method as claimed in any of claims 1 to 4, further comprising obtaining the expected braking performance from one of: an accessible memory in the rail vehicle and a remote server.

6. Method as claimed in any of claims 1 to 5, wherein controlling the rail vehicle to perform a rolling brake test comprises:determining a suitable location for the rolling brake test to be carried out; monitoring the geographical location of the rail vehicle;at the point the geographical location of the rail vehicle matches the suitable location for the rolling brake test, applying the brakes of the rail vehicle to bring the rail vehicle to rest or to a pre-determined reduced speed based on the calibrated set of vehicle characteristics; andmonitoring the performance of the rail vehicle during the rolling brake test.

7. Method as claimed in any preceding claim, wherein the method is performed on a processor on board the rail vehicle.

8. Method as claimed in any preceding claim, wherein outputting a recommendation for rail vehicle operation comprises one of:a) if the actual braking performance during the rolling brake test matches the expected braking performance during a rolling brake test, displaying an indication to a user that no changes to the rail vehicle operation are recommended;b) if the actual braking performance during the rolling brake test is better than the expected braking performance during a rolling brake test, displaying an indication to a user that changes to improve rail vehicle speed and braking curve are recommended; or c) if the actual braking performance during the rolling brake test is worse than the expected braking performance during a rolling brake test, displaying an indication to a user that changes to reduce rail vehicle speed and braking curve will be enforced.

9. Method as claimed in claim 8, wherein if reduced rail vehicle speed and braking curve are enforced, the rail vehicle is also halted immediately.

10. A data-processing system adapted to perform a self-calibrating rolling brake test on a rail vehicle, comprising:a processor adapted to receive an input set of rail vehicle characteristics; receive a set of independently verified rail vehicle characteristics; calibrate the input set of rail vehicle characteristics using the set of independently verified rail vehicle characteristics toproduce a calibrated set of rail vehicle characteristics; on the basis of the calibrated set of rail vehicle characteristics, control the rail vehicle to perform a rolling brake test; and compare the actual braking performance of the rolling brake test to the expected braking performance and output a recommendation for rail vehicle operation based on the comparison;a receiver adapted to receive the set of independently verified rail vehicle characteristics and to communicate the set of independently verified rail vehicle characteristics to the processor;a location device adapted to determine the geographical location of the rail vehicle and to provide this to the processor;an accessible memory device adapted to store details of suitable locations for rolling brake testing and accessible by the processor; anda display device adapted to display the recommendation for rail vehicle operation, wherein the processor, receiver, location device, accessible memory device and display device are connected via a data bus.

11. Data-processing system as claimed in claim 10, further comprising a user input device adapted to receive the input set of rail vehicle characteristics from a user, the user input device also being connected to the data bus.

12. Data-processing system as claimed in claim 10, wherein the input set of rail vehicle characteristics are stored in the accessible memory device.

13. A rail vehicle comprising the data-processing system of any of claims 10 to 12.

14. A rail vehicle as claimed in claim 13, wherein the rail vehicle is a train.

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