Railroad train monitoring system

[0001] The invention relates to a monitoring system for trains, etc., in particular to a system that uses an instrumented cover of a roller bearing housing to detect the occurrence and cause of poor performance at the level of a wheelset, platform, freight wagon and train.

BACKGROUND OF THE INVENTION [0002] More than ever, owners and operators of railway wagons need a better understanding of how their equipment works. With heavier wagons in operation, there is a greater need to identify undesirable factors (wagons that can damage the railway infrastructure and lead to derailment) as soon as their performance becomes unacceptable. There is also a need to increasemedium speed train by improving performance at high speed and reducing unplanned service interruptions due to mechanical damage. Wagon owners are increasingly trying to implement preventive maintenance programs to avoid mechanical damage and plan repairs at a place and time of their choice. Finally, with the increasing rail automation and the increasing number of safety regulations, the railway industry needs new ways to monitor the performance of trains, wagons and wagon platforms.

[0003] Some performance criteria to be monitored include the condition and temperature of the roller bearings, the displacement of the roller bearing housing, the condition of the wheels, rocking / warping / mounting the platform, condition and performance of the brake, whether there has been a partial derailment and potentially problematic condition of the platform. Since some of these performance problems could very quickly lead to catastrophic train damage, it is desirable to monitor and report exceptions to the locomotive or to the data center as soon as possible. In addition, taking into account the demanding environment in which railway trains operate, each system must be robust, reliable and able to operate for extended periods with little or no technical service. In addition, because of the profitability, installation and maintenance of the system should not require significant costs. Because there are more than 1.5 million freight wagons in North America and a monitoring system for all wagons is very desirable, each such system should be able to handle a very large number of potential devices.

[0004] One approach widely accepted in North America is the use of track fault detectors at predetermined locations within the entire rail network. Detectors measuring the temperature of the bearings (hot bearing detectors) are common, while other track detectors to measure wheel operation, bearing condition (based on acoustic signals) and lateral forces are gradually introduced. However, while one detector can monitor many passing freight wagons, they only provide random control of performance. It is quite possible that defects will become visible and increase to the critical level between the detectors. A system is needed for continuous monitoring of wagon performance.

[0005] Another approach to monitoring the performance of wagons was the use of on-board instrumentation. One such distinctive system has been developed for the Federal Railway Administration. In this and other similar systems, a number of instruments are used in various areas of the freight wagon to perform discontinuous measurements before sending them to the central concentrator in the freight wagon. Although they provide a better solution than those provided by track-based monitoring devices, cabling, complexity and cost, they increase the level of investment required to monitor wagons.

[0006] US 6,668,216 discloses a system for automatic, wireless short-range data acquisition on trains. A series of data transmission units communicate, in a serial manner between train wagons, with a control unit that is placed for data processing.

[0007] US 2005/0268813 discloses a bearing housing for a wagon platform, the bearing housing having an elastomeric cap of the housing mounted on it.

[0008] US 6,161,962 discloses a wagon bearing, the bearing having a sensor module that includes a plurality of sensors to monitor the operation and condition of the bearing. The sensor module includes a microprocessor to modify the raw signals produced in the sensor module to match transmission to the remote processor.

Summary and Objectives of the Invention According to the invention, there is provided a monitoring system for monitoring performance criteria of a wagon, said wagon comprising a body and a series of railway trucks each of which carries one or more wheelsets with wheel bearings attached to the frame supporting said car, wherein the system includes: one or more sensor units disposed in said carriage, wherein each sensor unit includes an elastomeric bearing pad between the bearing and the load carrying frame between the carriage and the rails, said cap providing damping of the load forces between the bearings and the frame; one or more sensors placed on said sensor unit, wherein said sensors measure parameters corresponding to the performance of said wagon; a processor unit placed on said unit

- sensor 3, wherein the microprocessor unit is programmed to: control the periodicity and frequency of taking samples from readings from said sensor or sensors and perform analysis of data collected by said readings; a communication unit disposed on said sensor unit for transmitting data selected as a result of said analysis; and a data control unit mounted in the wagon for receiving data sent from one or more of said sensor units and for sending signals characteristic of evaluating said performance to a receiver located away from said wagon.

[0010] The invention aims to provide means for continuous, in-use monitoring of behavior and condition, and to ensure both regular performance and if necessary warn operators and owners of threatening or damaged railway platforms, wheels and rail carriages bearings, forming part of the train, in a timely and useful manner.

[0011] It is a further object of the present invention that the performance of the wagon and its parts could be combined with operating data from the locomotive to ensure a complete train monitoring system. Another object of the present invention is to provide such functionality with minimal use of wired electrical connections between components mounted on the wagon platforms or between parts mounted on the platforms and parts mounted on other parts of the wagon and other parts of the train, including the locomotive.

[0012] It is a further object of the present invention that the parts can be inserted or removed for inspection and repair or replaced during standard maintenance of the wagons. It is a further object of the present invention to provide means for analyzing, at the appropriate time, measurements made during use of the train, so that performance or damage information can be sent in a concise manner so that no detailed measurement is needed.

It is a further object of the present invention that the transmitted performance or damage messages contain sufficient information to clearly determine the exact location of the item or points on the train and that the position of the train or indeed the freight wagon can be reported, if such information is available.

Another object of the invention is that, during wireless use, it can be extended to use available operating frequencies (channels) to relieve the interference from subsequent (adjacent) wagons on the train or other equipment operating in the same band frequency. Although in the following discussion the vehicle is described as a freight wagon, it should be understood that the same methods are used in each rail vehicle, or in some cases, in other multi-axle vehicles. Furthermore, although the following description presents a freight wagon with two platforms (or bogies), it can be used in any configuration with more or fewer platforms or axles.

- 4 Brief description of the drawings [0015]

Figures 1-3 are schematic views showing a part arrangement suitable for use in achieving the objectives of the present invention;

Figure 4 is a perspective view of the distributed platform portions showing the position of the instrumented pad according to the invention relative to the wagon platform; and

Figures 5-7 are schematic views showing alternative configurations of elements of the invention.

Detailed description of embodiments [0016] Turning now to Figures 1, 2 and 4, each of the platforms 1, shown schematically, has two axes 2 each with two wheels 3. Axial bearings 2a and bearing mountings 4, preferably shown in Figure 4, they are configured so that each bearing transmits the load it carries and the heat it can generate through the pads 16 on the platform.

[0017] Figure 4 shows a fragment of a wagon platform 1 showing the relationship of the instrumented pad 16 to other parts of the platform. Figure 4 shows one end of the platform side frame 12. Each side frame has a pair of 13 forks that extend to the bottom. The parallel side walls 14 of each axle fork along the roof section combine to form the opening of the forks.

[0018] The platform also includes bearing frames 4, one of which is shown in Figure 4. The fixtures have a generally rectangular upper surface with overhanging legs extending from the corners of the top structure. The legs have front curved side surfaces that are configured to rest on the outer surface of the bearing 2a mounted at the end of the bearing wheel axis 2. The fitting is usually made of cast steel. The housing cap 16 is generally rectangular in plan view and has hanging legs. The housing cap 16 is preferably made of cast or injected elastomeric polymer. The housing cap 16 is formed to be mounted on the upper surface of the housing 4, which, as indicated above, is mounted on the bearing. Binding and details of the overlay,

[0019] Referring now to Figure 2, the caps 4 are mounted on the upper rectangular surface of the bearing housing. Each bearing transmits the loads it receives and the heat it can generate through the cover and thus the wagon platform.

[0020] Figure 3 shows a schematic representation of the housing cover 16 modified to implement the objectives of the present invention. The cap includes a series of sensors 5, which are preferably incorporated in its upper, side and bottom surfaces or in other places, such as surfaces at its ends, which may be required in achieving the objectives

- the invention as explained in more detail below. In a preferred embodiment, the cap 16 has a stretched attached portion 17 arranged such that it is relatively isolated from the forces transmitted by the housing 16. The extracted portion 17 includes an energy source 18, analog means for signal conditioning, means for converting analog signals into a digital connected microprocessor unit 19 and a communication unit, which is preferably a low power radio transmitter / receiver with an antenna 21. The sensors are electrically connected to the analogue conversion unit and the microprocessor unit, which in turn is connected to and controls the communication unit, so that it can be sent and received messages. Various means can be used to power the overlay.

[0021] Alternatively, the energy source may consist of an energy recovery device that supplies energy to the battery or capacitor. You can use the source of electric energy obtained from stresses. Although the source of energy can be a body-mounted source, it will preferably be on the platform, and more preferably on the extension of the cap, so as to avoid the need for electrical wiring between the relatively moving parts of the car.

[0022] Figures 1-3 also show a freight wagon 22 having platforms 1 with overlays 16 with their associated sensors and units 19, 20 of the control and communication system. In the described example, each platform has four overlays 16 (one per bearing), each of which has an energy source 18, a control system unit 19 and a communication unit, and preferably includes a radio transmitter / receiver.

The data control unit 23 is mounted on the wagon body, preferably about halfway between the two wagon platforms, and has a radio receiver that can communicate with the radio receivers on the pads 4 on its wagon together with the microprocessor, the functions of which will be described in further part. The data control unit 23 is connected via a cable 23a to the communication device 24 shown here on top of the wagon, although other positions may be suitable depending on factors such as the wagon to which the invention is applied. Under certain conditions and for some types of wagons, the data control unit and communication device may be adjacent.

[0024] The communication device 24 is preferably powered by means of a solar cell designated by reference 24a or other electrical means capable of maintaining a continuous functionality. The communication device 24 serves to connect the wagon directly to the locomotive pulling the train in such a way that the engineer or technical service can immediately point out problematic wagons. Optionally, communication may take place by side means for automatically identifying equipment or for cellular or satellite radio systems or other equipment

- 6 communication to monitoring stations according to the user's needs. In the event that cable communication from the locomotive will be available throughout the train and, for example, electronic braking will be a standard, then the communication device will be able to be connected to this communication line. The power source for the communication device 24 can also provide energy for the data control unit 23a, in which case the electrical connection 23 can be a multi-contact connection.

[0025] Also shown in Figure 1 is a handheld unit 23b comprising a microprocessor and a radio receiver for communicating with the instrumented pad 16 by its radio receiver, as well as with the data control unit 23. The unit 23b, hereinafter referred to as "register", is designed with very limited data transmission capability, such that it must be physically located close to the overlays 16 or the communication unit 23 for communication to take place. This ensures that the operator will only communicate with one such device, and not with similar devices on other wagons in the same or nearby train receiving radio waves.

[0026] Although it is preferable to use a radio receiver to create communication by means of a registrar, direct electric contact can be used. However, due to the unfriendly environmental conditions to which railway wagons are exposed, direct electrical contact could reduce reliability and be slower, especially when communication with a large number of wagons is required. The use of a registrar to achieve the function of the invention will be further described below.

At this point it should be noted that the feature of the invention is to facilitate the setting of the address for radio communication during the installation of the overlay or during the exchange of the overlay or the data control unit. For this purpose, as an alternative to radio communication, a radio frequency identification (RFID) label or a corresponding bar code or other readable version of the extended address can be used, which can be read and registered by means of a registrar.

[0028] The antennas shown in Figures 1 and 3 are schematically illustrated in the form of a conduit or rod. In practice, they may be belt microleds or antenna systems adapted, and may be, for example, metal conductors on a ceramic plate.

[0029] Likewise, instead of powering the instrumented battery caps, an onboard electric power supply may be available in the wagon and, if available, may be used. Alternative energy recovery devices that receive energy from wheel rotation can be used to generate electricity. For practical reasons, when choosing a source of energy, priority should be given to a source of energy that can run for several years without the need to replace the battery or without the need for other maintenance work.

[0030] As noted above, a feature of the invention is that radio receivers within the pads 16 and the data control units 23 only require very short range communication. Radio receivers that comply with the standard are preferred for this purpose

- 7 IEEE802.15.4 for wireless sensor networks. This is a short-range standard, examples of which are ZigBee sensor network systems. The energy levels are low and the range is limited, but generally only the possibility of communication between the overlays on the platforms of the particular wagon and the data control units of the wagon or the register kept by the employee standing close to the wagon is required. The existence of standards for data formats and open software for using these systems with suitable microcontrollers makes this a preferred option. An especially attractive advantage of radio transmission is that cabling on platforms and cabling from wagon platforms is undesirable because it is exposed to interruption, and wiring along a freight train is unlikely to be accepted,

[0031] Means for wireless communication based on the IEEE standard are available and can be adapted to allow instrumented pads and control units to determine the connection network without outside intervention. They can be set to recognize the platform relationship and the position of the axle in the wagon or set so that the digital communication unit will be informed of the configuration, thus providing multi-hop means for connecting the network. The radio receivers used in implementing the above aspects of the invention are to be operated intermittently at low power. There are several frequency bands available in different parts of the world. The appropriate available frequency at which radio receivers will work in North America is around 2.4 GHz. Although it is preferred to accept

[0032] In the exemplary system, the instrumented pads 4 comprise several sensors for measuring dynamic and static vertical loads as well as shear and side forces generated by the platform of the carriages and hence through the goods car through the bearing housings. However, these are the forces that the axes, themselves rigidly attached to the wheels and exposed to the irregularities of the track, exert on the platform. Exemplary instrumented covers 16 also have temperature sensors to indicate the temperature of the associated bearings, because for safety reasons it is important that the bearing does not overheat.

[0033] Again with reference to Figures 1-3, in use, the microprocessor on the instrumented pad 16 is normally in a passive state requiring low power, but programmed so as to turn on periodically for a short time. It collects readings from each sensor and performs initial readings analysis. The selection of the frequency of sampling and selection of sensors to be read is based on the type of behavior monitored and the particular application. The sampling should take place at a frequency several times higher than the highest frequency to be detected from the data. More frequent sampling will not gather more information, but will increase energy consumption.

[0034] The periodicity of sampling and reporting is controlled by the data control unit 23. However, if pads detect error indications or threaten damage, the microprocessor on the overlay can be programmed to enable

- a radio receiver with which it controls and sends a corresponding message by the radio receiver to the data control unit 23. An example of such an event may be a sudden increase in temperature. The large short-term voltage increase produced by the energy recovery device can also be used to actuate the overlay microprocessor if it were then in a low power state. In the absence of such a problem, the overlay microprocessor follows its set plan, which would normally cause it to be in a low power state most of the time.

[0035] The data control unit 23 has the task to serve several purposes. It coordinates the cyclic testing of the instrumented overlay performed by the microprocessor and the timing of messages issued from it. As a program information aggregate, it is programmed to compare information from all platforms in a wagon and draws conclusions based on the wagon status, for example, the data control unit uses inference engine techniques to identify unsatisfactory behavior such as rocking, bouncing or even partial derailment . It transmits information from the communication device 24. For example, the communication device 24 may include means of measurement, such as a global positioning system, to provide information about the speed of the vehicle, which is useful when checking platform behavior, such as rocking. The information can also be used to stop the sensor control when it does nothing to reduce energy consumption.

Similarly, if necessary, factor detectors, such as ambient temperature and humidity (rain, snow and icing) may be incorporated into the communication device 24 or the data control unit 23 in a separate inference apparatus operating according to the use described below. In addition, the data control units 23 or the communication device 24 may include a three-axis accelerometer or speed gyro to effect certain modes of analysis or to check the readings made by the overlay and provide information about the various movements of the wagon body.

[0037] As a wire, the data control unit 23 transmits messages on the communication device for further transmission to the locomotive or other remote receivers and picks up, for its own analysis and distribution to the overlays if necessary, information or instructions from, for example, the locomotive or from another remote source.

[0038] Alternative configurations for the monitoring system described in Figures 1-3 are illustrated in Figures 5-7. In the example shown in Figure 5, each instrumented pad 16 has its own microprocessor and radio receiver. This system is to use a network creation protocol that allows messages to be forwarded between the overlays on their way to and from the digital communication unit 23.

[0039] In the embodiment of Figure 6, all pads 16 from one platform communicate with a single unit of the microprocessor and radio receiver 24, passing along the 27 multi-wire cables. It minimizes the number of electronic parts

- 9 at the expense of a large number of wired connections on the platform. The computational work performed in the microprocessor unit on the platform may be slightly different from that of the microprocessor unit of Figure 5. In this embodiment, all analogue-to-digital conversion functions are performed in the microprocessor and each inference function performed there evaluates all sensors for all overlays on the platform.

A further alternative embodiment is shown in Figure 7. In Figure 7, each instrumented pad 16 has its own analog-to-digital conversion unit that can be incorporated into the microprocessor 28 on a particular overlay. These microprocessors can then communicate with a single data service unit 25 on the platform and hence with the data control unit 23. As in the configuration of Figure 6, any inference or analysis of the data performed in the unit 25 takes into account the information from the sensors on all overlays on the platform.

[0041] Other options include standard CANBus communication schemes that use cable connections. In addition, CANBus or other standards can be implemented in the event of large-scale introduction of electrically controlled air brakes, potentially providing other options for communication schemes.

[0042] Communication along the train can be provided in various ways. WiFi (IEEE802.15.11 standard) may be suitable for very long freight trains. The Rail Transit Vehicle Interface Standard, IEEE1473-199, would be appropriate for communication along passenger trains.

[0043] Furthermore, it should be noted that in principle it would be possible to communicate the instrumented pads along the train by forwarding messages from one freight car to the next. However, in the case of long trains, this results in multiple message skipping, which is generally less reliable than a single high power connection from each wagon to a locomotive or other remote location. Other problems include the likelihood that the trains will reconfigure, which means that the freight wagons can be removed or mixed or the train will be pulled by the locomotive from the opposite side. Any such network dependent on the connections between the overlays from the connections between the wagons would require reconfiguration of the train in marshalling yards.

[0044] As indicated above, it is a feature of the invention to have appropriate means for addressing and identifying each instrumented pad in the wagons used in the system. Furthermore, it is necessary that instrumented pads on platforms in neighboring freight wagons, whether or not on the same train, continue to operate within their radio ranges without mutual interference. It must be possible to create trains from any freight wagons and to replace a single overlay on the platform without the need to replace all other overlays on the platform or freight wagon. Even if there are no problems to report, it is important for the system to ensure that it is still working correctly. The preferred system described herein is used for this purpose

- 10 messages initiated by instrumented overlays. An alternative to using data control units to check the status of instrumented pads requires that the pads engage and act as receivers at a strictly controlled time and in periods that require a longer performance at full power than if they are allowed to send messages based on their own timing from requiring that the data control units are always in the receive mode.

[0045] The instrumented pads to be mutually interoperable with the corresponding data control units must use matching frequencies. The previously mentioned IEEE802.15.4 standard specifies the frequencies or channels in each frequency band. For example, in the ISM band at 2.4 GHz there are 26 channels. There is also a standard for the message pattern, so each creates a multiplex of 8-bit data bytes, where each bit has a predetermined meaning. Within this pattern, one byte is specified for the group number, and two bytes are specified for the address within the group. The next byte is specified for the type of message that can be interpreted as a command. The associated radio receivers and their controlling microprocessors are designed to ignore messages received from a source in another group. They do not detect messages on other frequencies than their selected operating frequencies. However, they can change work channels (frequencies) through program control. They can respond appropriately to messages that belong to their own group. For use on railway lines, a large number of devices will be required that can be covered by a two-bit address and moreover, means are provided so that the data control unit can recognize messages from the instrumented pads on its own freight car. The instrumented pads must be able to recognize messages from their own data control units and both must be able to tolerate potential interference from instrumented pads and data control units on other nearby freight wagons in the same or on a passing train. They must also be able to tolerate potential interference from other devices operating in the same unlicensed band.

[0046] The identification number or address may be programmed in the electronic module during manufacture.

The address for the instrumented pad may additionally or alternatively be stored in the RFID label (radio identification) or included in each pad 4. The physical location of the pad on the platform results in it being close to the tracks. In particular, it could be on the outside of the side frame of the platform and thus close to the track monitoring equipment. This enables at least identification of passing devices with permanent equipment and, if active RFID label technologies are used, enabling an alternative communication path from the wagon to the central database or owners.

[0048] The address may be conveniently visible as a readable number optionally with a bar code for the convenience of users, although a demanding working environment may make this alternative limited in use.

[0049] It will be clear that any addressing scheme that provides sufficient individual addresses or identities can be used. The overlay address can be made in accordance with the extended communication protocol addressing scheme (IPv6), using 6 bytes, so that these devices can have their own IP addresses.

[0050] The preferred embodiment described below can be extended to use multiple channels (radio frequencies), thus providing means for actually eliminating interference between neighboring wagons on the train.

[0051] The essential aim of the invention is the ability to monitor the behavior of all platforms, bearings and wheels on the train. The alarm message must get from each wagon to the locomotive or remote data service as soon as possible, preferably within a few seconds.

[0052] However, the transmission load of all data that can be retrieved during the monitoring is very large and for the most part the details are not significant. Preferably, only the observations that suggest some error or inappropriate behavior are recognized. To reduce radio traffic to serviced parts, the system is designed to process primary data from the sensors, searching for fault signals and then sending only relevant characteristic information. For this purpose, a distributed inference apparatus is used, dividing essential functions between the microprocessors at the instrumented pads and at the data control unit 23. The object of the invention is to reduce the radio traffic between the pads and the data control unit in such a way,

[0053] In the exemplary system illustrated above, the microprocessors 19 with the instrumented pads 16 perform a series of measurements and treat them as a time series. Search algorithms that create an inference engine can identify, for example, periodicity and cross-correlations within and between time series in such a way that any behavior detected at the overlay level will be visible. For example, rolling the platform back and forth along the railway line is at the frequency specified by the platform geometry and wheel rotation speed. Side swinging and wagon oscillation takes place at frequencies dominated by mass-elastic suspension and load systems. To varying degrees, depending on the construction of the vehicle, these behavioral irregularities will be evident in varying load and load distribution in instrumented pads that can detect, for example, vertical, cutting and braking forces. The irregularities of the wheels make repetitive models of forces at the rotation frequency, which can be calculated on the basis of vehicle speed. Disadvantages of the track can generate large and sudden forces in the wheels, bearings and platform and further in the wagon and its load.

[0054] If such behavior is requested with instrumented pads and the magnitude is sufficient to trigger an alarm, appropriate attributes and timing (in

- 12 referring to the transmission time of the declaration) can be transferred to the wagon data control unit.

[0055] Assuming that more than one instrumented pad can report the wrong behavior, then the components of the inference apparatus in the data control unit take responsibility for making evaluations for the entire platform and ultimately for the freight wagon. When a serious disturbance is requested, then messages are sent over the communication link 23a, 24 to the locomotive, etc.

[0056] Examples of performance that the system can monitor include:

[0057] Bearing Temperature - A temperature sensor in the instrumented pad 16 monitors the relative temperature changes relative to other bearings and provides an alarm threshold or long-term trends to link to the condition of the bearing. A good condition of the roller bearing can be requested using trends or alarm levels, avoiding the potential burnout of the bearing and possible derailment and providing a direct measurement that can be used to avoid false alarms from the side welded bearing detectors. Another object of the invention is to compare the observations from side temperature detectors and other results with those of the on-board calibration and control system.

[0058] Bearing condition - Use of a load sensor in the upper part of the instrumented pad 16 to monitor the vibrations emitted by the bearing (transmitted by the roller bearing housing). Certain bearing defects may be requested based on frequency spectrum analysis. Identifying a faulty bearing at an early stage is important in preventive maintenance programs.

[0059] Wheel condition - A load sensor in an instrumented pad for detecting loads with high amplitudes (compared to the background) that are periodically repeated (function of wheel diameter and speed) to identify a flat or shell rolling surface. It may also be possible to identify hollowed-out empty wheels using some of the other sensors in the instrumented pad. Wheels monitoring may allow the wheel owner to plan a wheel change before the Wheel Load Detector is identified, resulting in unplanned maintenance. It can also provide insight into the cause of the damage.

[0060] Wheel derailment - The use of the same tooling for the Wheel State, but the search for a higher frequency and a similar signal from both wheels in the wheel set. Identification, when a set of wheels derailed, prevents a possible complete derailment and possible catastrophic consequences.

[0061] Platform Rocking - Using load sensors mounted in the instrumented pad to detect longitudinal, lateral and lateral forces, monitor rapidly changing loads (and hence the angle of attack of the wheel set) indicative of swinging the axle or platform. By analyzing such loads monitored from both sets of wheels on the platform and two platforms in the wagon, it is possible to identify platform and axle swinging as well as warping the platform. Additionally, by evaluating the angle of attack of the wheel sets on

- on each platform, the high speed friction caused by binding side bearings or dry middle bowls can be identified. Identifying these states allows to prevent damage to freight carriages and cargo platforms as well as railway infrastructure.

[0062] Wagon weight - Sum of the load measured in all eight instrumented pads on a freight wagon to determine its mass. Even the estimated measurement (say plus / minus 10% of the full load) will provide useful information for the task of assessing the performance of freight wagons and their parts. Another advantage is the detection of load disproportions due to improper loading or displacement during transport.

[0063] Shifted roller bearing housing - By monitoring the load in the legs of the instrumented pads, it can be identified when the roller bearing housing has been moved. This provides information on the reason for the displacement, as well as the urgent technical service required to avoid damage to the roller bearing.

[0064] Braking condition and efficiency - Monitoring of the longitudinal forces at the instrumented pad provides information about the force applied from the wheel brake pad friction plates. This can provide insight into the braking performance; too large braking loads indicate that the brakes can jam the wheels, too low braking loads indicate that the brakes do not work properly. In addition, the brake status control can be used to send an alarm signal if the train is traveling with some hand brakes.

[0065] Disadvantages of track - Monitoring of vertical loads in instrumented pads and comparing them between wheel sets provides owners with insight into track defects that may cause damage to freight wagons or their load.

[0066] While several alternatives have been identified above in relation to device configurations and for communication between them, a preferred embodiment is described later.

[0067] It will be obvious to those skilled in the field of micro-controller programming and the protocols and capabilities of both low power and satellite or cellular communication that the functions described herein are achievable with existing technology and parts. For example, the Micaz remote low power sensors made by Crossbow Corp., of Palo Alto, California, with Embedded ChipCon radios can perform the Overlay and Data Control Unit functions. The 24 communication device is a DS300RDT model made by Stellar-Sat, Inc. This device has a considerable computing power, so that some of the functions assigned to the data control unit 23 can be performed in the DS300-RDT. In fact, two devices can be connected or their functions can be divided in such a way that the distinction may be unnecessary.

[0068] The power source consists of an energy recovery device, such as a piezoelectric foil from Measurement Specialties, Inc., of Hampton, Virginia, together with a charge condenser or an electric accumulator.

[0069] The instrumented pads are programmed in the production with the group number, the channel number and a unique extended address that is stored in non-volatile memory and selects the data in the RFID label and the barcode, if used. With the appropriate programming, the number of available addresses for various instrumented overlays can increase as much as necessary.

[0070] The group number serves, which is the norm in such IEEE802.15.4 systems, to distinguish this application from others that can use the same radio frequency (channel).

[0071] When the overlays are installed, their expanded addresses are read by the register 23b, which is provided to collect RFID data or barcodes. The user instructs the registrar using his keypad and screen, which place on the platform and hence, and in the freight wagon is occupied by each overlay. The registrar is then placed near the data control unit 23 and using a radio channel, provides data on the address and location of the pads in the freight wagon of the data control unit to the data control unit.

[0072] To avoid using means for RFID or bar codes, the registrar may alternatively use overlay and electronics functionality that is programmed to always send messages whenever it has available power. These messages, as described in the following, always contain an extended overlay address so that the registrar can collect it when it is near the overlay. This operating mode has the disadvantage that it requires the pad to be electrically energized to carry out the dialogue, which is not advantageous if the pad is to be powered with normal operation by means of energy recovery means. If additional means are provided for supplying electricity, e.g. by induction, radio communication is preferred.

[0073] The registration of the overlay data could alternatively be forwarded to the data control unit by other means, for example via a data link 24. In any case, the data is recorded in the data control unit in non-volatile memory, so that temporary power loss does not force the registration to be repeated. The registration process allows you to track devices within the entire railway system.

[0074] As soon as the identities of the overlays are entered in the data control unit, further transmissions from the instrumented pads will be recognized by the data control unit if they come from registered instrumented pads. Similarly, further transmissions from the data control unit may be routed to the correct instrumented pads.

[0075] Unrelated messages that are retrieved from nearby instrumented pads and data control units are not a problem if they do not collide temporarily with

- 15 desired messages. They can simply be ignored. If they collide, the messages will contain errors. However, using the standard IEEE802.15.4 standard for cyclical redundancy check of messages, they will not be recognized and will therefore be omitted. To minimize this problem, the data control unit supports timing of messages to and from its own instrumented overlays.

[0076] Initially, the instrumented pads will start sending messages at a rate of one minute or at a similar rate as soon as they are energized. This message, sent as for any recipient, but with the correct group number and in the appropriate channel, carries the address of the overlay as the sender's address. This is the only type of message that is sent as an advertisement in this diagram. Then the overlay waits for a short answer. The data control unit, when powered, acts as a receiver, and thus retrieves a message. Because it can recognize the sender's address as belonging to one of the overlays for which it is responsible, it immediately responds with a message that instructs the overlay, which collection task to perform and when (with what delay) report back. The overlay is programmed so that every message, which uses its own full address is accepted as originating directly or indirectly from its control data control unit and automatically sends responses back to that sender. As a result, the overlays will not need further addressing instructions for the rest of their useful life, because they will automatically download the instructions and send them back to any device that addresses them directly and is close enough. After receiving a message from the data control unit, the overlay can return to low power (sleep mode) until it has to perform its next task. As a result, the overlays will not need further addressing instructions for the rest of their useful life, because they will automatically download the instructions and send them back to any device that addresses them directly and is close enough. After receiving a message from the data control unit, the overlay can return to low power (sleep mode) until it has to perform its next task. As a result, the overlays will not need further addressing instructions for the rest of their useful life, because they will automatically download the instructions and send them back to any device that addresses them directly and is close enough. After receiving a message from the data control unit, the overlay can return to low power (sleep mode) until it has to perform its next task.

[0077] This scheme allows the overlays to stop operation due to the loss of recovered energy and still return and be in a connected state with the appropriate data control unit until the power is restored.

[0078] The diagram allows the exchange of the data control unit in the network by providing the addresses of the overlays for which it is responsible. A single overlay can be exchanged in the network by providing its ID with the appropriate data control unit.

[0079] The scheme also allows other devices in the network to be operated if they only have an associated, near data control unit.

[0080] Before all the instrumented pads belonging to the data control unit will be after the communication queue, they are included in the schedule, which calls them in sequence over time which the data control unit can predict. The instrumented pads are essentially devoid of communication in a transitional period to save energy.

[0081] The message scheduling scheme in the system intentionally keeps messages from the instrumented pads on a single freight car separated in time in such a way that radio signal collisions are avoided. Because the instrumented pads themselves work only briefly as receivers, the risk of receiving false ones

- 16 messages are also small. Since the planned radio transmissions from the instrumented pads are very short, e.g. a few milliseconds, compared to the transient quiet periods, the chances of collisions of radio signals from neighboring freight wagons or other completely independent devices are also small. However, they will eventually appear. The standard approach to the IEEE scheme is that the radio receiver to send the signal first goes into the receiver mode to see if any other is sent in the channel. If so, it delays the sending of a random amount of time related to the length of the message. This procedure excludes most collisions.

[0082] If the expected, scheduled message from the instrumented pad does not come within a significant period of time, then the data control unit may take a number of different actions. It can sometimes detect that the message has been received but contains errors. Knowing that the sending tooled pad will temporarily wait for a response, it can send a message instructing a small random change in timing in such a way that if the problem comes from an adjacent freight wagon, then the next message will most likely pass.

[0083] Accordingly, the instrumented pad can repeat its message out of schedule if it does not receive a response in such a way that the data control unit, always powered and normally operating as a receiver, will shortly download and may, as in the initial startup process, assign a new scheduled time for transmission. The data control unit can wait another cycle to see if it was a random event, it can mute its remaining instrumented pads for the moment they call, in such a way that they do not interfere with transmissions from the missing device. With this or similar strategies, instrumented overlays and data can take steps to restore communication. Finally, if all fails, the data control unit reports a loss of communication over communication link 23a.

[0084] It is a feature of the invention that the pads never stop attempting to contact the data control unit for as long as they have sufficient power, and no external message to the Overlay is able to stop this process, even though before the next notification it is naturally acceptable is long, but not indefinite, delay.

[0085] With established communication, the data control unit instructs the overlays that the data collection task is to perform and when to report them back to provide information in order to be able to carry out the interference indicated above. Such tasks include, but are not limited to: measuring temperature, taking medium forces, providing spectral data on lateral, vertical or longitudinal forces, measuring vertical forces through cycles at the wheel rotation frequency. Each of these measurement sequences corresponds to a particular application that can be extracted if the data justifies it.

[0086] For each task, the waiting time before reporting is assigned. For each task, a time is assigned in which the measurement should be made or periodicity is assigned.

[0087] Tasks may require that the pads perform intermediate measurements and temporarily store them between the intervals in the radio reports. These direct, synchronized actions can be taken without the intervention of the data control unit. Between these actions, the overlays go back to low power sleep mode provided there is enough time to restart, and the process leads to energy savings.

[0088] Each application sent back by the overlay identifies the task that has been requested and the time that has elapsed since the data in the set was collected.

[0089] Each request includes state information (status byte) of the functionality of the overlay parts, in particular of the sensors.

[0090] The set of requests includes the option of requesting a report of the strength of the received signal as a communication control.

[0091] The data control unit schedules reporting times in such a way that radio transmissions do not interfere with each other.

[0092] The data control unit may parameterize data requests with associated information, such as ambient temperature or vehicle speed. The commands that select the measurement task may be dependent on the location using GPS information. The commands can be influenced by the measured accelerations in the data control unit when this is possible.

[0093] The data control unit has a default measurement program, by means of its overlays as data collectors, so that regular assessments of the behavior of the freight wagon are made in a timely manner. However, this regular pattern can be changed by commands sent to the data control unit from the central database or by instructions from the owners or operators.

[0094] The data control unit in its information aggregator role combines data from the overlays and performs the adjustment required due to the slightly different time in which the data was reported and collected. The data control unit then performs the assessments described above for the inference engine to check whether the freight wagon, its platforms, wheels or axes behave so inaccurately that it is necessary to report to the central data service location, operator or locomotive owner. If so, you can send a notification. It is important to minimize the data sent, because the data transmission can be estimated on the basis of the quantity, and there can be many wagons sending data. Nevertheless, the data control unit will plan to send the "all right" message at appropriate intervals if everything is fine.

[0095] The rules for assessing the performance of a freight wagon are designed to tolerate missing data, since it will be obvious from the above system description that due to the

- 18 communication difficulties or the severity of the part environment may not be able to provide all requested data.

[0096] Because this preferred embodiment delegates the initiation of data dialogue to the overlays, another advantage is that if an extreme condition occurs, the overlay can send an unforeseen report at any time between the scheduled reporting intervals. To minimize data traffic, the same approach is taken when sending data from the data control unit to the central database.

[0097] For the version of the invention, which may use several (e.g., 26 in the 2.4 GHz band) available operating frequencies, the following additional properties may be added. Central data control can learn from the GPS data that the wagon pairs are actually adjacent. If the wagons report communication problems, then one of these pairs may be informed on the basis of communication, from the control panel to the wagon, to switch to another channel. IEEE802.15.4 device networks can be programmed to jump between frequencies based on mutual agreement to avoid interference. In the event communication is lost, such devices will transmit messages in the sequence of differential frequencies until the response provides the basis for re-establishing the communication. Limiting the selection and pre-defining the sequence of frequencies to be tested speeds up the process of returning to the normal state. The system can also be programmed to provide targeted frequency changes by sending instructions to this as part of a regular dialogue between the overlays and the data control unit.

[0098] In this way, the objects of the invention are implemented by the means described.