The invention relates to a method and apparatus for wireless monitoring of tire conditions, including, for example, conditions such as tire pressure and/or temperature. The method and apparatus can be used to provide real-time monitoring of tire condition while the vehicle is in use.
Existing systems provide wireless monitoring of vehicle tires on multi-tire vehicles such as articulated trucks. Sensor assemblies typically comprise an antenna that transmits status information to a monitoring unit on the vehicle. A display unit can be used to indicate the status or condition of tires. Examples of these systems can be found in United States Published Patent Application No. 2011/0043354 to Shepler et al, U.S. Pat. No. 5,963,128 to McClelland et al., and U.S. Pat. No. 6,945,103 to Lee et al.
Existing systems may not be suitable in circumstances when there is a requirement for a remote monitoring station to maintain information about the vehicle's status and where the vehicle is only intermittently within range of the remote monitoring station. In these circumstances, it is also important for a driver or operator of the vehicle to be aware of the tire status or condition, and to receive alerts when irregular conditions occur. Existing display systems can also lead to driver distraction. Thus, there is a need to improve the visual and audible information supplied to the driver in a way that reduces distraction, and makes diagnosis and monitoring a simple activity.
In some vehicles such as low-floor, articulated buses, it can be difficult to achieve the required sensitivity, at the monitoring unit on the vehicle, to signals transmitted by sensor assemblies located on the wheels or tires. Therefore, there is also a need to have a configuration of transceivers on the vehicle that provide higher sensitivity than might be achieved by having more than one antenna and only one transceiver.
Existing systems provide limited data transfer and offloading capabilities. There is also a need for on-vehicle monitoring units to have a wide variety of data transfer and offloading options.
Sensor assemblies in existing systems act as transponders. These systems have limited accuracy and flexibility. For example, it is desirable to be able to calibrate sensor assemblies during manufacture for greater accuracy, and to have the flexibility to change the parameters defining sensor operation while the vehicle and the wireless monitoring system is in use.
A method for wirelessly monitoring tire conditions on a vehicle comprises sensing a tire condition, for example, using one or more sensor assemblies on the vehicle; wirelessly transmitting sensed data related to the tire condition to at least one communication module mounted on the vehicle; and sending a signal from the communication module to a display unit mounted on the vehicle so that an operator can monitor tire conditions in real time. During time periods when the vehicle is not within an RF coverage zone provided by one or more remote monitoring stations, the sensed data related to the tire condition is stored in non-volatile memory in the communication module. When the vehicle moves into an RF coverage zone of a remote monitoring station, real-time sensed data related to the tire condition and stored data from the non-volatile memory is wirelessly transmitted, via an RF modem, to the remote monitoring station. For example, historical data related to the tire condition that was stored in the non-volatile memory when the vehicle was not within an RF coverage zone is transmitted to the remote monitoring station when the vehicle moves into an RE coverage zone. When the vehicle is within an RF coverage zone, real-time sensed data is wirelessly transmitted to the remote monitoring station, and is optionally also stored in the non-volatile memory in the communication module.
In some embodiments of the method, the real-time sensed data continues to be transmitted by the communication module, via the RF modem, even when the vehicle is not within any of the RF coverage zones provided by the one or more remote monitoring stations.
In some embodiments of the method, there is two-way communication between the one or more remote monitoring stations and the sensor assemblies via the communication module when the vehicle is within an RF coverage zone provided by the one or more remote monitoring stations. For example, the method can further comprise transmitting parameters to the sensor assemblies from the at least one remote monitoring station, via the communication module and a transceiver in the sensor assembly, for calibration of sensors in the sensor assemblies or for updating parameters in the sensor assembly to adjust operation of the sensor assembly.
A method for generating calibrated sensor data from a sensor assembly, used in a system for wirelessly monitoring tire conditions on a vehicle, comprises activating the sensor assembly and causing the sensor assembly to enter a calibration mode. For the purposes of calibration, measurement data is transmitted from the sensor assembly to a receiver while the sensor assembly is maintained at a known steady temperature and pressure. Transmission of measurement data from the sensor assembly is repeated at four or more temperature and pressure measurement points, and calibration coefficients of a function are generated that describe the relationship between the measurement data and the known temperature and pressure measurement points. The calibration coefficients are then downloaded to the sensor assembly. Next, the sensor assembly exits the calibration mode and enters a working mode in which the sensor assembly can be used for wirelessly monitoring tire conditions on the vehicle. In the working mode, calibrated sensor data are generated at the sensor assembly from raw sensed data and using the calibration coefficients stored at the sensor assembly.
A system for wirelessly monitoring tire conditions on a vehicle comprises a plurality of sensor assemblies mounted on the vehicle. Each sensor assembly comprises at least one sensor for sensing a tire condition and generating associated sensor data, and a transceiver for communication of the sensor data. The system further comprises at least one communication module mounted on the vehicle for two-way communication between the sensor assemblies and at least one remote monitoring station. Each communication module comprises at least one transceiver and at least one antenna for communication with the sensor assemblies; a radio frequency (RF) modem for wireless communication with the at least one remote monitoring station, each remote monitoring station providing an RF coverage zone; and non-volatile memory for storing sensor data received from the sensor assemblies. A display unit is mounted on the vehicle and is configured to receive signals from the at least one communication module and relay the signals so that an operator can monitor tire conditions in real time. The communication module is configured to store sensor data received from the sensor assemblies in the non-volatile memory while the vehicle is not within any of the RF coverage zones. The communication module is also configured to transmit real-time sensor data from the sensor assemblies and stored sensor data from the non-volatile memory via the RF modem to a remote monitoring station when the vehicle is within the RF coverage zone of that remote monitoring station. For example, the stored sensor data transmitted from the non-volatile memory can be sensor data generated while the vehicle was not within any of the RF coverage zones. Optionally, the communication module is configured to also store sensor data received from the sensor assemblies in the non-volatile memory while the vehicle is within an the RF coverage zone.
In some embodiments, the system actually comprises at least one remote monitoring station. In some embodiments, the system further comprises at least one repeater for relaying sensor data to the at least one remote monitoring station, and the communication module is configured to transmit real-time sensor data from the sensor assemblies and stored sensor data from the non-volatile memory via the RF modem to the at least one remote monitoring station via the at least one repeater.
In some embodiments of the system, the communication module comprises one transceiver per antenna, for communication with the sensor assemblies.
In some embodiments of the system, the communication module further comprises an RS-232 driver, an Ethernet driver, a CAN driver, and/or a Wi-Fi driver for offloading sensor data stored in the non-volatile memory.
In some embodiments of the system, each sensor assembly further comprises a processor configured to modify sensor data based on calibration parameters stored at the sensor assembly.
In some embodiments of the system, each sensor assembly further comprises an activation mechanism that initiates operation of the sensor assembly in response to at least one of a signal from the communication module, a magnetic switch, or movement of the vehicle.
In some embodiments of the above-described method and system for wirelessly monitoring tire conditions on a vehicle, the tire condition is tire pressure and/or tire temperature.
The present invention relates to a wireless monitoring system and method that can be used to provide real-time monitoring of tire status while a vehicle is in use. The system and method can accommodate the vehicle going in and out of wireless coverage. Real-time sensor data on tire status is logged on the vehicle and transmitted to a remote monitoring station in real-time when the vehicle is within wireless coverage. When the vehicle goes out of wireless coverage, the real-time sensor data continues to be logged on the vehicle and is wirelessly transmitted to the remote monitoring station once the vehicle returns to wireless coverage. Wireless coverage can be provided in a number of zones around the remote monitoring station using one or more optional wireless repeaters.
The system provides diagnostic and monitoring information to the driver of the vehicle by means of a display unit that can provide visual and/or audible signals. The display unit is designed not to distract the driver unduly, and can provide an audible alert, for example, when there is an alarm condition requiring the driver to stop the vehicle. A diagnostic capability allows the driver to identify the location and nature of an irregular condition at one of the sensors e.g. an overheated tire.
In some embodiments, the sensor configuration and operational parameters are programmable. The communication module on the vehicle provides multiple data transfer and offloading options, both wired and wireless. In some embodiments, the module is designed as a network within a network, with one transceiver per antenna to improve sensitivity and each antenna able to communicate wirelessly with one or more sensor assemblies. In this configuration, each transceiver is dedicated to a particular antenna. Sensor assemblies can be calibrated during manufacture to achieve higher accuracy.
The status of each tire can be measured by sensors on a sensor assembly.
As indicated in
In an example embodiment shown in
The communication between antennas 120A-C and sensor assemblies 125A-F is wireless (as indicated by the dotted lines in
The rear communication module 130B is connected to a single antenna 120D which is in turn able to communicate wirelessly with four sensor assemblies 125G-J. As with the front module 130A, the antenna 120D is located to provide wireless coverage of the four sensor assemblies 125G-J taking into account possible blind spots.
Referring to
Data from sensor assemblies (e.g. 125A through 125D) can be transmitted over a wireless data channel to the remote monitoring station 170 for the purpose of monitoring real-time tire status such as temperature and pressure while vehicle 110 is within RF coverage of the remote monitoring station 170. In some embodiments, data can be transmitted over a wireless connection to a remote or remote monitoring station 170 via an optional repeater when vehicle 110 is out of range of remote monitoring station 170. When vehicle 110 is out of range of remote monitoring station 170 and repeater 160, data from sensor assemblies (e.g. 125A through 125D) are logged at the communication module 130, and offloaded to remote monitoring station 170 when the vehicle is once again within range. In some embodiments, data from sensor assemblies can continue to be transmitted when vehicle 110 is out of range of remote monitoring station 170 or repeater 160 even though the data is not being received by remote monitoring station 170 or repeater 160.
Signals can be transmitted to a display unit 140 via a power line 150 in vehicle 110, regardless of whether vehicle 110 is within RF coverage of remote monitoring station 170. Signals transmitted to display unit 140 can comprise alert, status and identification information intended for diagnosis and monitoring by the driver.
The remote monitoring station 170 can communicate with a remote monitoring terminal 180 via a network 190 (such as the Internet).
The embodiment shown in
Data can be transferred from remote monitoring stations 170A and 1706 to a remote monitoring terminal 180 via a network 190 such as the Internet. This allows an operator connected to network 190 to monitor tire status information in real-time and to view stored data offloaded from the communication module 130 from
Data can be transferred between remote monitoring stations 170A and 1706 via a network 190 such as the Internet.
RF coverage zones are provided by remote monitoring stations 170A and 170B, and by repeaters 160A, 160B and 160C. Other embodiments may have different numbers and configurations of remote monitoring stations and repeaters.
In the example embodiment illustrated in
When communication module 130 from
Communication module 130 provides a variety of options (in addition to RF modem 260) for data transfer or offloading of sensed tire status data and other real-time monitoring information. Module 130 comprises an RS-232 driver 220, an Ethernet driver 230, a CAN driver 240, and a Wi-Fi module 250, some or all of which can be used to offload data stored on module 130.
Alarm signal generator 270 can send signals to display unit 140 from
During time periods when the vehicle is not within an RF coverage zone provided by one or more remote monitoring stations (such as remote monitoring station 170), the sensed data related to the tire condition is stored in non-volatile memory 280 in the communication module 130. When the vehicle moves into an RF coverage zone of a remote monitoring station (e.g. 170), real-time sensed data related to the tire condition and stored data from non-volatile memory 280 is wirelessly transmitted, via RF modem 260, to the remote monitoring station. For example, historical data related to the tire condition that was stored in non-volatile memory 280 when the vehicle was not within an RF coverage zone is transmitted to the remote monitoring station when the vehicle moves into an RF coverage zone. When the vehicle is within an RF coverage zone, real-time sensed data is wirelessly transmitted to the remote monitoring station, and is optionally also stored in non-volatile memory 280 in communication module 130.
When communication module 130 moves within range of repeater 160 or remote monitoring station 170, remote monitoring station 170 can send a command to communication module 130 to request the offloading of historical sensed data stored in non-volatile memory 280 via the RF modem to remote monitoring station 170.
Sensitivity of transceivers 210A through 210D is important to operation of communication module 130. Sensitivity of −70 dBm to −80 dBm is expected. Higher than expected sensitivity (for example −102 dBm) can be achieved in communication module 130 with suitable layout and grounding of the printed circuit board (PCB). The transceivers can be connected without using a splitter. This may be beneficial in increasing sensitivity by 6 dBm for example. Software can also be used to configure the transceivers for improved sensitivity.
Communication module 130 shown in
The transceiver 340 can be used during manufacturing of sensor assembly 300 for the purposes of calibration. The performance of sensor assembly 300 can be measured and coefficients calculated and downloaded to sensor assembly 300 by a calibration control unit (not shown). The accuracy of the system is increased by providing calibrated coefficients to each sensor assembly 300.
Power is provided to sensor assembly 300 by battery 330 or another suitable energy storage device.
Sensor assembly 300 can comprise a low frequency (LF) wake-up receiver 360 used to activate sensor assembly and/or to cause sensor assembly 300 to transition between different modes of operation (see
In one embodiment, sensor assembly 300 can comprise a roll-ball switch 370 used to detect motion of sensor assembly 300 as a result of motion of vehicle 110 from
Sensor assembly 300 can comprise central processing unit (CPU) 380 connected to other elements such as transceiver 340. In some embodiments, CPU 380 may comprise a processor configured to modify sensor data based on calibration parameters stored at the sensor assembly.
Communication via power line 450A and 450B can comprise transmitting data packets according to a suitable protocol. For example, data packets may comprise a preamble, a pattern and data. In one embodiment, data packets may comprise an alarm data byte itself comprising eight bits—one each to indicate whether an alarm is pressure or temperature, and three bits each to indicate an alarm tire axle and an alarm tire position on the alarm tire axle. Any suitable alternative protocol and encoding of the data may be used.
The tire status indicator on the dashboard of the vehicle can provide information to the driver whether or not the vehicle is in contact with the remote monitoring station. The tire status indicator can alert the driver to the occurrence of an irregular condition in one or more of the sensor assemblies, provide status information on the condition (such as the nature of the condition e.g. an irregular temperature or pressure) of the sensor assemblies (e.g. 120A through 120D from
Alerts can be signalled by the use of audible and/or visual indications. In one embodiment, the dashboard indicator comprises a red LED and a yellow LED. The yellow LED may also be referred to as an orange light. The red LED can be used to show temperature alerts, and the yellow LED can be used to show pressure alerts. Various sequences can be used to alert the driver and indicate the nature of the irregular condition. For example, a sequence can be used in which the red and orange lights flash three times each in an alternating pattern. The sequence of flashes can be accompanied by an audible alert such as for example the sound of three beeps. After the initial alert sequence, the dashboard indicator can be used to indicate the nature of the irregular condition. For example, in one embodiment the red light can remain ON if an irregular temperature condition exists. Similarly, the orange light can remain ON if an irregular pressure condition exists. If both temperature and pressure irregularities exist, then both the red and orange lights can remain ON. In some embodiments, the indicator lights can remain ON until the irregular condition ceases to be present, at which time the corresponding indicator light(s) can turn off.
In the example embodiment illustrated in
In one embodiment of the status sequence, the tire status indicator can show status information indicating whether the irregular condition currently exists or has ceased to exist. If the irregular condition still exists, then the alert sequence can be repeated. For example, the red and orange lights can flash three times each in an alternating pattern or any other suitable pattern. The flashing can be accompanied by an audible alert such as three audible beeps. After the alert sequence has been repeated, the red light can remain ON if an irregular temperature condition exists, and the orange light can remain ON if an irregular pressure condition exists. If both temperature and pressure irregularities exist, then both red and oranges lights can remain ON.
In one embodiment, if the irregular condition ceases to exist, the red and orange lights can flash together three times. The flashing can be accompanied by an audible alert such as three beeps.
Once the status sequence completes, the method proceeds to step 540 where the tire status indicator waits a predetermined period of time (e.g. 2 s) before proceeding to the identification sequence 550. The identification sequence indicates in which sensor assembly the irregular condition exists. In the case where the irregular condition has ceased to exist, the identification sequence indicates the sensor assembly with the most recently reported irregular condition. In the identification sequence, more detailed information such as the identification and/or location of the sensor assembly can be provided by means of a visual indication on the tire status indicator.
Any suitable pattern can be used to identify the sensor assembly. In one embodiment, each axle position can be allocated a number from 1 through to the total number of axles on the vehicle in a sequence known to the operator (e.g. front to back). The red light can indicate the axle position of the sensor assembly by flashing a number of times equal to the number of the axle comprising the sensor assembly with the irregular condition (or the most recently reported irregular condition). Each tire position can be allocated a number from 1 through to the total number of tires per axle in a sequence known to the operator (e.g. driver side to passenger side). The orange light can indicate the tire position of the sensor assembly by flashing a number of times equal to the number of the tire comprising the sensor assembly with the irregular condition (or the most recently reported irregular condition).
At the end of the identification sequence 550, the red light can remain ON if an irregular temperature condition continues to exist and/or the orange light can remain ON if an irregular pressure condition continues to exist. If an irregular condition ceases to be present (or is corrected), the corresponding light can turn OFF.
If the vehicle goes out of range of the remote monitoring station or one of the repeaters (NO), then the method proceeds to step 630 and the system continues to monitor the tire status in real-time and logs the information on-board the vehicle in the communication module. During this time, the communication module can send alerts, status and identification information to the display unit. When the vehicle restores wireless contact with the remote monitoring station or the repeater, the communication module transmits the stored data to the remote monitoring station.
Referring to
In some embodiments, LF activation may be required to change mode so that the sensor assembly is ready to accept new sensor parameters.
In calibration mode 830, the sensor assembly transmits data to a receiver for test purposes using any suitable packet format. From this data, coefficients can be calculated that can be used to compute one or more calibrated sensor outputs, e.g. calibrated temperature and/or calibrated pressure. Since temperature and pressure depend on one another, at least four measurement points are necessary to define the coefficients for calibration. These four points may for example be −30° C. at 0 psi, −30° C. at 150 psi, +80° C. at 0 psi and +80° C. at 150 psi. The data is fitted to a curve and the coefficients of the fit are downloaded to the sensor assembly after calibration is complete. Calibration requires the sensor assembly to be producing stable output in a stable pressure and temperature environment at the desired pressure and temperature values. Calibration is performed, and separate coefficients are calculated, for each sensor assembly entering calibration mode 830.
In some embodiments, calibration may increase accuracy of pressure readings from say ±7 psi (with no calibration) to ±1 psi (with calibration). Accuracy of temperature output may increase from say ±10° C. to ±1° C.
After coefficients have been downloaded to the sensor assembly, the sensor assembly proceeds to sub-calibration mode 840 in which the coefficients are verified by means of testing. The calibration sequence then proceeds to factory mode 850 which is the same as working mode 870 except that no RF activation is required. Mode 850 is for the purposes of testing. When the sensor assembly is ready to ship from the factory, the sequence proceeds to deep sleep mode 860. Before installation, for example in vehicle 110 from
While in working mode 870, the sensor assembly checks the sensor output (e.g. tire pressure and temperature) and transmits it to the communication module with any suitable ancillary data (such as state data) at a predetermined reporting interval. While in working mode 870, calibrated sensor data are generated at the sensor assembly from raw sensed data and using the calibration coefficients stored at the sensor assembly. The raw sensed data are the data received from the sensor before calibration.
When the sensor assembly has spent a pre-determined period of time below a pressure threshold (for example 5 psi), such as might occur if it is removed from the tire, the sensor assembly enters wake-up on radio mode 880. Upon entry to mode 880, the sensor assembly stops transmitting and waits for either a wake-up command, operation of a magnet switch, activation via an LF signal, or the pressure to rise above a threshold (e.g. 10 psi). Mode 880 may be beneficial for example in the case the sensor assembly is removed from a vehicle and may be necessary for FCC approval.
In some embodiments, the sensor assembly can be activated or caused to transition between modes by means of roll-ball switch 370 from
Where a component is referred to above, unless otherwise indicated, reference to that component should be interpreted as including as equivalents of that component any component which performs the function of the described component (i.e., that is functionally equivalent), including components which are not structurally equivalent to the disclosed structure which performs the function in the illustrated exemplary embodiments of the invention.
As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. For example, features from any of the embodiments described herein may be combined with features of other embodiments described herein to provide further embodiments.
This application claims priority from U.S. Provisional Patent Application Ser. No. 61/457,798, filed 6 Jun. 2011, under 35 U.S.C. §119(e), which is incorporated in its entirety by reference herein.
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCT/CA2012/000545 | 6/6/2012 | WO | 00 | 11/26/2013 |
Number | Date | Country | |
---|---|---|---|
61457798 | Jun 2011 | US |