WO2002036368A1

WO2002036368A1 - Earthmover tire monitoring system

Info

Publication number: WO2002036368A1
Application number: PCT/US2000/029945
Authority: WO
Inventors: Didier Gaborit; Stephen B. Jahries; Pourang Mahdavi; Bernd Volkwein
Original assignee: Michelin Recherche Et Technique S.A.; Societe De Technologie Michelin
Priority date: 2000-10-30
Filing date: 2000-10-30
Publication date: 2002-05-10
Also published as: AU2001214463A1

Abstract

A system for monitoring earthmover vehicle tires (12), comprising at least one sensor unit (20) mountable within the pressurizable interior of a tire, the sensor unit including a pressure sensor and a temperature sensor, an integrated circuit including memory to collect and store data and to store at least pressure and temperature reference data, a radio frequency interface to transmit received data externally, a magnetic interface for receiving activation, input and deactivation signals, a power circuit, and a microprocessor circuit having a timer for activating pressure and temperature data collection at fixed intervals; a reader (30) mountable on the vehicle remote from the tire, the reader having a receiver for receiving data transmitted from the at least one sensor unit, a memory for storing data received from the at least one sensor unit, and a radio frequency transmitter for transmitting data remote to the vehicle responsive to an external signal; and a portable communication unit (50) comprising a means for communicating with the sensor unit and the reader, a memory for storing data received from the sensor unit and the reader, and a display for displaying received data in visual format.

Description

EA THMOVER TIRE MONITORING SYSTEM

BACKGROUND OF THE INVENTION

The present invention relates to devices for monitoring the operating conditions of tires, including but not limited to pressure and temperature. More specifically, the invention relates to a system for monitoring the operating conditions of tires of large, heavy vehicles such as earthmovers and haul trucks. DESCRIPTION OF THE ART

Earthmoyer vehicles or haul vehicles are large vehicles capable of carrying extraordinarily heavy loads. There are haul vehicles for mining operations, for example, that can carry loads of approximately 240 to 360 tons. These vehicles are operated under harsh environmental conditions (e.g., high desert temperatures) on rugged ground (e.g., sharp stones causing punctures), which is highly damaging to the tires. Tire damage can occur quickly, putting a vehicle unexpectedly out of service. Because the vehicles are typically operated on tightly controlled schedules for efficient production, the unscheduled loss of use of a vehicle is generally very costly. Tires are typically one of the top three expenses in mining operations. Because damage to the tires of mining vehicles can arise quickly, it is important to closely monitor the condition of the tires, in particular the pressure and temperature. Operation at excessive temperature or abnormal pressure (either too high or low) can contribute to premature tire failure. In addition to lost productivity time, a tire for an earthmover can cost in the neighborhood of $20,000, making maintenance of the tire important in keeping operating costs down.

Manually checking the pressure and temperature of these tires is undesirable during the operation of the earthmover or haul vehicle. Manually checking the pressure and temperature would require stopping the vehicle so that a pressure gauge or temperature measuring device could be connected to the tire's valve stem. Because the vehicle would be taken out of service, valuable production time is lost. In addition, taking the measurements requires an operator to perform and record the data, adding labor costs.

Telemetered monitoring systems developed for the long haul trucking industry typically include a monitoring device mounted at a fixed location in a service area. The device collects data from truck tires when a truck drives into a service area from the highway. It is known in such systems to interrogate the sensor in the tire for obtaining data, that is, the data collecting device sends a wake up signal to the tire sensor to request a data transmission. In a mining operation, such systems may not provide data on a sufficiently frequent basis to detect high temperature or under or over pressure conditions before permanent damage occurs in a tire.

Thus, it would be desirable to provide a monitoring system for monitoring large earthmover type tires for specific parameters such that operational time on the vehicle is not diminished and valuable production time is not lost.

SUMMARY OF THE INVENTION The present invention provides a system that continually monitors certain parameters, such as the pressure and temperature, of earthmover and other large haul- type vehicle tires and periodically transmits the data to a remote receiver for processing and storing the data. The system according to the invention maintains a history of the tire for the useful lifetime of the tire.

The system of the present invention comprises at least one sensor unit, or tag, mountable in the tire to be monitored, a reader unit mountable on the vehicle to receive information from the at least one sensor unit, and a hand-held unit for reading from the sensor unit and reader unit and for writing to the sensor unit. The system in accordance with the invention may be functionally integrated into a management system station to communicate tire data for use in operational control.

The sensor unit is preferably mountable within the pressurized internal space of a tire. A particularly advantageous location is on the tire sidewall near the tire bead, which is usually relative thin, helping communication, and which usually experiences relatively little distortion during rolling. The sensor unit includes an antenna for radio frequency transmission, and when mounted in a tire is preferably orientated in the tire with the antenna parallel to the steel reinforcing cables in the carcass to optimize radio transmission. A typical mine haul truck or earthmover has six tires and, accordingly, a sensor unit would be installed in each tire. The sensor unit further includes at least a pressure sensor, a temperature sensor, a power circuit, and an integrated circuit for collecting and storing data from the various tire sensors. The sensor unit periodically collects pressure and temperature measurements from the sensors using predetermined, timed intervals.

The sensor unit also includes a radio transmitter for transmitting data to the reader. After a predetermined number of collection periods, preferably three or four, the sensor unit transmits measurement data together with other tire information, i.e., tire position and operation history, to the reader. If, on the other hand, the sensor takes data during any of the periodic collections that indicates a potential problem, a temperature or pressure out the normal operating range, an alarm is immediately transmitted to the reader unit. The reader relays the alarm to the on-board display or mine management system.

The integrated circuit of the sensor unit also includes magnetic interface means for receiving and storing data identifying the tire, such as the tire identification number, vehicle identification number, tire brand, size, the tire position, installation date, tread depth, and damage history. Such information, which is part of the "tire record card," is stored for each tire of a particular vehicle.

The reader unit is preferably mountable to the earthmover or haul vehicle in a position where it can readily receive radio transmissions from the sensor units in the vehicle tires and not be subject to environmental damage (e.g., thrown rocks). The reader unit stores the last measurement values from the vehicle tires together with a database containing the operating hours and other tire record card information. The reader unit also maintains maximum and minimum pressure values recorded and maximum temperature values recorded for the life of the tire. The reader may be connected to an on-board display in the vehicle, and/or to a central station.

The handheld unit is a tool utilized for the initialization or "software mounting" of the sensor unit on a particular tire, which involves entering relevant tire data into the sensor unit and activating the sensor unit to begin collecting and transmitting data. The hand held unit is also utilized for communicating with the reader, reading the measurement and tire record card information from the reader, and transferring the data to a tire tracking system, which may be a mine management system.

The data link from the sensor unit to the reader is achieved through high frequency radio transmission. The data link between the handheld unit and the sensor unit is accomplished via a short-range magnetic link, and not radio frequency. In addition, the handheld unit can communicate with the reader through high frequency radio transmission.

The communication procedure in accordance with the invention requires a smaller battery for the sensor unit then would otherwise be demanded. Because the sensor unit automatically initiates transmissions to the reader on a preprogrammed basis, it does not listen for an interrogation or request. In addition, the magnetic communication interface between the sensor unit and handheld unit requires low power. Advantageously, the required battery would typically outlast the tire, and, thus, will not require changing during the life of the tire.

The monitoring system can be integrated for communication with a management system to use the tire information for controlling the operation and use of the vehicle. For example, if the system data indicates that a tire on a particular vehicle needs attention, the vehicle can be rerouted by the management station to less demanding tasks, or directed to a maintenance station for immediate attention. In addition, the information allows the management station to adjust the movement of other vehicles to compensate for the lost service of the rerouted truck.

More particularly, the invention provides a system for monitoring earthmover vehicle tires, comprising at least one sensor unit mountable within the pressurizable interior of a tire, the sensor unit including a pressure sensor and a temperature sensor, an integrated circuit including memory to collect and store data and to store at least pressure and temperature reference data, a radio frequency interface to transmit received data externally, a magnetic interface for receiving activation, input and deactivation signals, a power circuit, and a microprocessor circuit having a timer for activating pressure and temperature data collection at fixed intervals; a reader mountable on the vehicle remote from the tire, the reader having a receiver for receiving data transmitted from the at least one sensor unit, a memory for storing data received from the at least one sensor unit, and a radio frequency transmitter for transmitting data remote to the vehicle; and a portable communication unit comprising a means for communicating with the sensor unit and means for communicating with the reader, a memory for storing data received from the sensor unit and the reader, and, alternatively, a display for displaying received data in visual format.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood through the following detailed description read in conjunction with the appended drawings, in which:

Figure 1 is a schematic of a system in accordance with the invention for monitoring earthmover tires;

Figure 2 is a schematic of the sensor unit in accordance with the invention; Figure 3 is a block diagram of the hardware of the handheld unit; and,

Figure 4 is a schematic of the communication links between the sensor unit and the handheld unit.

DETAILED DESCRIPTION Figure 1 is a schematic of a system for monitoring tires on earthmovers or other large haul vehicles in accordance with the present invention. The vehicle and vehicle tires do not form a part of the present invention. The monitoring system according to the invention is mountable on a vehicle and in the tires to perform the functions described herein. In addition, the invention is described as being capable of being linked or integrated with an onboard vehicle display system and a mine management system, but neither is considered part of the invention.

As shown, a vehicle 10, such as an earthmover, has a plurality of tires 12, typically two steer position and four drive position tires. Each tire is equipped with a sensor unit 20 or tag. In a preferred embodiment, each sensor unit 20 is disposed within a container (not shown) for shielding the sensor components from dirt and moisture that may be present in the tire. A reader 30 is mountable to the earthmover 10 in proximity to the vehicle tires 12 to facilitate reader 30 reception of transmissions from the sensor unit 20, which is further described below. Information from the reader 30 may be periodically displayed on a vehicle display 40 or a mine management system to report normal tire conditions or instantly displayed on the cab display 40 to report warnings of potential emergency conditions. The sensor unit 20 is capable of communicating not only with the reader 30 but also with a remote hand held unit 50, as further described below.

The reader 30 includes a radio receiver to receive information transmitted from the multiple sensor units 20 operating on the vehicle 10. The reader 30 may also be connected tlirough hardwiring to the cab display 40 or mine management system via, for example, an RS232 or RS422 connection. The sensor unit 20 transmits to the reader 30 data contained in the tire record card (defined herein) and maintained by the sensor unit 20, including but not limited to: air chamber temperature, actual inflation pressure, temperature compensated inflation pressure and associated alarms. The reader 30 stores data received from the sensor unit 20 in memory for subsequent transmission to the in-cab display 40 or mine management system.

The reader 30 can also receive requests for information from the hand held unit 50, such requests capable of being received from a distance of at least 60 feet, and more typically several hundred feet, from the vehicle 10. The reader 30 is powered by the vehicle electrical system. The reader 30 memory preferably is of the type that does not require power to maintain its memory so that data is not lost in the event of a vehicle power loss. When the vehicle 10 is off, the reader 30 will not be required to receive transmission from the sensor unit 20 or communications from the hand held unit 50. The hand held unit 50 communicates with the sensor unit 20 via a magnetic interface which generates a magnetic field at an antenna 52. The hand held unit 50 is used to "software mount" (initialize), inspect, and "software dismount" (de-initialize) the sensor unit 20. The hand held unit 50 is also capable of entering information into the sensor unit 20 which is used to track tire 12 operation data.

The hand held unit 50 also communicates with the reader 30 with radio frequency transmission for quick, "on the fly" measurement of the pressure and temperature of all tires 12 on the vehicle 10.

A management station 60 can be set up to collect and analyze data received from the sensor unit 20 to manage the operation of a vehicle, which is particularly advantageous in mining operations. The management station 60 typically monitors all aspects of the operation, including the movements of a fleet of haul trucks. Decisions for routing vehicles and removing vehicles for service can be best made from a central station to take into account the entire operation and therefore minimize disruptions. For example, if the system indicates that the temperature of a tire on a particular vehicle is above a normal temperature, the management station can re-route the vehicle 10 to less demanding tasks to allow the tire to cool. Other vehicles can be routed to account for the change in the re-routed vehicle. If a pressure abnormality is detected, the management station can direct the vehicle 10 to a maintenance station for pressure adjustment.

Figure 2 is a schematic of the sensor unit 20 in accordance with the invention. In a preferred embodiment of the present invention, the sensor unit 20 comprises a microprocessor unit 70 that is an ultra-low-power processor. The microprocessor unit 70 may be any processor such as the processor from the Texas Instruments MSP430 series. The microprocessor unit 70 will preferably comprise a programmable memory unit 72 having 32K-bytes of program memory and lK-bytes of random access memory (RAM) 73. In the preferred embodiment of the invention, the memory unit 72 will store individual sensor and customer data. The sensor unit 20 will preferably have sufficient memory to permanently store data "hard" coded during the manufacturing process, data entered via the hand held unit 50, and data generated internally by the sensor unit 20 when in operation.

The microprocessor unit memory will store reference data, including, but not limited to the following: the recommended cold pressure; a minimum pressure (for example, calculated as recommended pressure minus 50 kPa); a maximum pressure (for example, calculated at 1.25 times the recommended pressure); and a maximum temperature value of 80° C. In a preferred embodiment, the pressure sensor operates to read absolute pressure in a range of 100 kPa (14.5 psi) to 1100 kPa (150 psi). The temperature sensor operates in a range of -40° C to 85° C.

The memory may also include multiple alarm levels for temperature and pressure, that is, values of temperature and pressure that will trigger an alarm being sent to the reader 30. The levels are set relative to maximum safe operating temperature and recommended cold inflation pressure, and are chosen so that the alarms are sent before tire damage is imminent. This allows the mine management system or other control system to order corrective action before tire damage or failure occurs. For example, the memory includes three alarm levels for each of temperature and pressure. For temperature, a first level alarm is set at 85% of the maximum temperature, a second level temperature alarm set at 90% of the maximum temperature, and a third alarm level is set at 95% of the maximum temperature. Alternatively, a two level alarm procedure would use 90% and 95% of the maximum temperature to trigger sending an alarm. The memory may also include three pressure alarms, including a first level alarm set at the recommended cold inflation pressure +/- 5%, a second level alarm set at the recommended cold inflation pressure +/- 10% and a third level alarm set at the recommended cold inflation pressure +/- 15%. An alternative two level procedure would use +/-5% and +/-10% of the recommended cold inflation pressure as the alarm triggers. These alarm points are used by the system to initiate the transmission of an emergency signal to the reader (as described herein). Additional memory may also be allocated for free data fields for later use.

The sensor unit 20 of the present invention also comprises a timer control unit 74 that measures time intervals between data collection operations by the sensor unit 20. For example, in a preferred embodiment of the invention, the timer control unit 74 is preprogrammed or fixed at 5 minute intervals for sensor unit measurements of specific tire parameters, such as pressure and temperature.

The sensor unit 20 automatically transmits routine data to the reader 30 at predetermined intervals that are multiples of the predetermined measurement interval. This allows the system to conserve power while still transmitting often enough to provide "real time" feedback to the user. For example, and preferably, the sensor unit 20 may transmit to the reader 30 after every third data collection interval, or every 15 minutes based on 5 minute measurement intervals. At regular transmission intervals, the sensor unit 20 will transmit latest collected pressure and temperature information to the reader.

The reader 30 includes a sensor diagnostic function. If a particular sensor unit 20 fails to transmit data over a predetermined number of periods, for example, three or four, the reader 30 will report a malfunction of the specific sensor unit 20 to the vehicle display or mine management system. In addition, once each day, the sensor unit 20 transmits a complete set of data, that is, the tire record card, to the reader 30.

As mentioned, if the sensor unit 20 takes a measurement which is outside of normal operating values, the sensor unit 20 sends an emergency transmission to the reader 30 immediately, that is, without waiting for the next transmission interval. The emergency transmission will be repeated an appropriated number of times, i.e., three to four times, to ensure receipt by the reader 30. However, the sensor 20 will not transmit the emergency transmission again until the emergency situation changes (the temperature or pressure reaches another alarm level) or the regular, non-emergency preprogrammed interval has elapsed.

The sensor unit 20 includes a micro-capacitive pressure and temperature sensor 76 capable of producing a digital output. The pressure and temperature sensor 76 is preferably not sensitive to moisture or current leakage.

The sub-circuits of the sensor unit 20, including but not limited to the temperature and pressure sensor 76, are powered by a battery 78, which is controlled by a power management control system 80. The power management control system 80 includes a watchdog 81 that senses both battery voltage and activities of the microprocessor 70 and the system forces the sensor unit 20 to reset when error conditions occur. The sensor unit 20 includes a radio frequency transmitter 84 (described below) to transmit measurement and other data to the reader and hand held unit. The sensor unit 20 does not include a radio frequency receiver. The sensor unit 20 and hand held unit 50 communicate reciprocally by way of a magnetic interface 82. The magnetic interface 82 of the sensor unit 20 achieves coupling through an antenna generating a magnetic signal with the antenna 52 of the hand held unit 50 at approximately 126 kHz. The magnetic interface 82 transmits data by modulation of the magnetic field. The magnetic signal produced by the hand held unit 50 has a range that is limited to about 25 cm, i.e., short-range, to prevent cross talk between sensor units 20 and to prevent unwanted communication with a sensor unit on another tire. The magnetic interface 82 of the sensor unit is operable in this short-range for the entry of data into the tag without physical contact.

The RF transmitter 84 preferably comprises high-speed transmission circuitry in accordance with the IEEE standard for wireless LANs 802.11 and operates using direct sequence spread spectrum at approximately 2.45 GHz. Data exiting the microprocessor 70 first enters a high-speed buffer 86 that provides a data stream to a mixer 88. Inside the mixer 88, data is combined with the output of a voltage control/synthesizer circuit 90 such that the frequency of the microprocessor 70 output is digitally controlled to about 2457 MHz. The synthesized mixer 88 output is then amplified in a power amplifier 92, filtered in a filter unit 94 and then transmitted via an antemia 96 to another portion of the system, such as the reader 30 or the hand held unit 50.

Figure 3 is a block diagram of the hardware of the hand held unit 50. The hand held unit 50 of the present invention is preferably a battery powered, rechargeable module for transmitting and receiving through magnetic coupling and through radio frequency information concerning the individual tires 12 of a vehicle 10. A hand held unit 50 modeled on the specifications of the Symbol Technologies Inc. hand held inventory model, for example, may be used in accordance with the present invention. The hand held unit 50 will preferably have a display screen (not shown) and a data entry means (not shown) for manual entry of data to transmit to the sensor unit 20. In a preferred embodiment of the present invention, the hand held unit 50 comprises an anteima 53 for receiving RF transmissions from the sensor unit 20 or the reader 30. The RF transmission received by the anteima 53 is passed via the radio printed circuit board (or board) 54 to the digital board 56 of the hand held unit 50. The hand held unit 50 further comprises a magnetic interface anteima 52, which is used to write data to and read information from the sensor unit 20. The magnetic interface antenna 52 passes information received from the sensor unit 20 to the digital board 56 and visa versa. In a preferred embodiment of the present invention, the hand held unit 50 may further comprise an atmospheric sensor 58, which is utilized to correct sensor unit 20 readings for current environmental conditions, such as ambient temperature and atmospheric pressure.

Data received and stored by the hand held unit 50 in its digital board 56 may be viewed from the hand held unit 50 memory, or may be downloaded from the hand held unit 50 to a standard PC through a user serial interface 59, with an option to clear the hand held unit 50 memory upon download completion.

Figure 4 is a schematic of the communication links between the sensor unit 20 and the hand held unit 50. The hand held unit 50 comprises a digital board 56, including the radio interface 154 and the atmospheric sensor 58. A software server resides in the digital board 56 to handle all frames between the hand held unit 50 and the sensor unit 20. The main board 55 of the hand held unit 50 is connected to the digital board 56 by a serial link. The sensor unit 20 transmits to the digital board 56 by the RF interface 154 or the magnetic interface 152, and receives data from the digital board 56 through the magnetic interface 152.

During sensor unit 20 activation or mounting, the hand held unit 50 sends out frames over the magnetic interface 152 in a periodic manner to the sensor unit 20. The sensor unit 20 then sends an acknowledgement back to the hand held unit 50 over the magnetic interface 152. The acknowledgment may be either audible or visual or both. As a result of the acknowledgement, the hand held unit digital board 56 sends an activation indication frame to the hand held unit main board 55 over the serial link. The main board 55 then sends a connect request frame to the sensor unit 20.

After connection is established between the sensor unit 20 and the hand held unit 50, frames from the hand held unit 50 are transmitted to the sensor unit 20 over the magnetic link 152 and response frames from the sensor unit 20 are transmitted back to the hand held unit 50 over the RF link 154. The connection between the sensor unit 20 and the hand held unit 50 may be terminated by the hand held unit 50 sending a disconnect frame, or by the sensor unit 20 in the event of a time-out condition, (e.g., a time-out condition occurs when the sensor unit 20 goes for a specified interval of time without receiving a data frame).

The hand held unit 50 may also be used to update tire information when the tire is moved from one position on the truck (e.g., steer position) to another position (e.g., drive position). The hand held unit 50 also is used dismount or deactivate the sensor 20 once the tire 12 is removed from service. During either the activation, data input, or dismounting, a user will be able to input or write onto the sensor unit 20 information such as: information registering the sensor unit 20 to a specific tire 12 in a specific wheel position; information encoding the current average of barometric pressure and the recommended cold inflation pressure; user name and site; tire serial number, brand, manufacturer, size and type; operation date, odometer reading; minimum tread depth; disposition and any damage coding. The above information, or a combination thereof, constitutes a tire record card. The tire record card may be transmitted by the sensor unit 20, modified within the sensor unit 20, or deleted therefrom in accordance with the user's use of the tire 12. Some tires are retreaded after the original tread has worn out. The sensor unit can stay with the tire carcass to provide a service life history of the carcass to help manage the use of retreaded tires. The invention has been described in terms preferred embodiments, structures, and processes. The invention, however, is not limited to what is literally described and those skilled in the art will recognize that substitutions may be made without departing from the scope and spirit of the invention as defined by the following appended claims.

Claims

CLAIMSWE CLAIM:

1. A system for monitoring earthmover vehicle tires, comprising: at least one sensor unit mountable in the pressurizable interior of a tire, the at least one sensing unit including a pressure sensor and a temperature sensor, a microprocessor circuit including memory to collect and store data from the pressure sensor and temperature sensor and for storing at least pressure and temperature reference data, a radio frequency transmitter to transmit received data externally, a magnetic interface to receive activation, input and deactivation signals, and a power circuit, the microprocessor circuit having a timer for triggering pressure and temperature data collection at fixed intervals and for transmitting received data at fixed intervals; a reader mountable on the vehicle remote from the at least one sensor unit, the reader having a receiver for receiving data transmitted from the at least one sensor unit, a memory for storing data received from the at least one sensor unit, and a radio frequency transmitter for transmitting data to a receiver remote to the vehicle; and, a portable communication unit including at least a radio frequency interface for communicating with the reader and a magnetic interface for communicating with the at least one sensor unit, a memory for storing data received from the at least one sensor unit and the at least one reader, and a display for displaying received data.

2. The system as claimed in claim 1, wherein the portable communication unit radio frequency interface is receptive of transmission from tlie at least one sensor unit.

3. The system as claimed in claim 1, wherein the portable communication unit includes means for activating and deactivating the sensing unit through magnetic interface communication.

4. The system as claimed in claim 1, wherein the portable communication unit includes means for manually entering data into the portable communication unit for transmission by the magnetic interface to the at least one sensor unit.

5. The system as claimed in claim 1, wherein the at least one sensor unit includes means for comparing data received from the temperature sensor and pressure sensor with the reference data stored in the memory and for generating messages based on the compared data, the messages including a warning signal to be transmitted to the at least one reader if received data exceeds a reference data value.

6. The system as claimed in claim 1, wherein the at least one sensor unit includes means for storing a vehicle identification code and the reader includes means for storing a vehicle identification code, the reader further including means for comparing the vehicle identification code of the sensor unit with that stored in the at least one reader before accepting data from the at least one sensing unit.

7. The system as claimed in claim 1, wherein the at least one sensor unit includes means for storing a wheel position identification code and the reader includes means for storing a wheel position identification code, the reader further including means for comparing the wheel position identification code of the sensor unit with that stored in the at least one reader before accepting data from the at least one sensing unit.

8. The system as claimed in claim 1, further comprising a plurality of sensor units for mounting one sensor unit in each vehicle tire pressurizable interior.