KR20170099555A - Tire Pressure Monitoring System for low power - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-power TPMS communication system, and more particularly, to a low-power TPMS communication system capable of sensing a running state of a vehicle to prevent unnecessary RF transmission.
According to the present invention, unnecessary RF transmission can be prevented by detecting the running state of the vehicle, and only the necessary measurement data is transmitted according to the situation to restrict the use of unnecessary bits, so that the optimal TPMS low power operation can be performed. It is possible to satisfy the high reliability according to the occurrence of the emergency situation and to minimize the loss due to the data collision of the sensor node of the other vehicle by distinguishing the sensor node using the sensor ID in case of an emergency.

Description

[0001] The present invention relates to a low power TPMS communication system,

The present invention relates to a low-power TPMS communication system, and more particularly, to a low-power TPMS communication system that detects a running state of a vehicle and prevents unnecessary RF transmission.

A typical tire pressure monitoring system (TPMS) is defined as a system in which a sensor attached to a tire measures tire pressure and temperature information and transmits it to a monitoring device that can be identified by the user. This TPMS allows the user to check the pressure and temperature conditions of all tires through the display device every time the vehicle is started, and can prevent the accident by judging the dangerous situation by the display device or the danger signal when the tire dangerous signal is detected.

The initial TPMS of the tire used an indirect method that uses the deviation of the number of revolutions of the tire wheel of a vehicle rather than a direct method in which a sensor having a high resolution sensitivity such as today is mounted in a vehicle tire. However, The proportion of direct methods is gradually increasing due to the development of technology.

Conventionally, according to the TPMS system disclosed in Japanese Laid-Open Patent Publication No. 2013-0061247, there is provided a TPMS system including an acquisition step of downloading a unique preamble signal of an antenna module (AM) in a hand tool, A storing step of storing a preamble of the antenna module, and a transmitting step of transmitting tire information including a preamble and a sensor ID from the tire sensor to the antenna module using radio frequency communication at the start of the automatic learning.

The tire air pressure sensing system (TPMS) generally uses unidirectional communication. When using bi-directional communication, it is necessary not only to transmit the signal of the monitoring part by installing the RF receiving device in the sensor node, but also to send and receive a lot of data packets between the sensor node and the monitoring part, .

Unidirectional TPMS communication has a communication structure for unidirectionally sending data from a sensor node to a monitoring device, not a method of checking the status of another node and sending data while exchanging ACK and NCK like bi-directional communication. The unidirectional communication frame structure is composed of information bits and guard bits which contain various information such as frame synchronous bits, signal bits, pressure and acceleration, and transmits data frames at regular time intervals in the same form.

The existing unidirectional TPMS communication method has two disadvantages. First, since data is transmitted at the same time intervals without considering whether the vehicle is in a stationary state or a traveling state, power is wasted, which is devoid of a low power communication target that the TPMS module is aiming at. In addition, since the channel is frequently accessed, the possibility of data collision with another sensor node using the channel increases. Secondly, since the priority of the sensor information importance can not be known by sending only a data frame of the same size without considering the vehicle being in a stationary state or a traveling state, the information of low priority is continuously transmitted, High-priority information can be lost due to collisions, which can be another cause of TPMS module safety, which is an obstacle to safety.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a low-power TPMS communication system that can detect unnecessary RF transmission by sensing a driving state of a vehicle.

A low power TPMS communication system according to the present invention is a low power TPMS communication system including a sensor node and a monitoring device, the system comprising: a system management frame unit for registering the location of the sensor node; A general data frame unit for transmitting sensor measurement values of the sensor node to the monitoring device; And a warning data frame unit for transmitting warning information together with a sensor measurement value which has reached a warning status in comparison with a predetermined warning standard. The vehicle control unit detects a running state of the vehicle and uses T, P, and V bits indicating frame information And to transmit only measurement data.

Preferably, the system management frame unit includes a frame type module for specifying a system management frame type; A spare field module for adding sensor information bits to the header of the data; A link address module for storing a location address of the sensor node; A sensor ID module for storing the product serial number of the sensor; An acceleration X-direction module for storing an X-direction acceleration value measured by the acceleration sensor module in the TPMS sensor node; And an acceleration Z-direction module for storing an acceleration value measured in the Z-direction measured by the acceleration sensor module.

In addition, the system management frame unit, the general data frame unit, and the warning data frame unit may further include an error detection field module for detecting an error in the frame.

The general data frame unit includes a frame type module for specifying a general data frame type; A spare field module for adding sensor information bits to the header of the data; A link address module for storing a location address of the sensor node; And a data frame module for transmitting only measurement data using a temperature bit (T), a pressure bit (P), and a battery level bit (V) representing frame information.

In addition, the general data frame section includes a first sensor node classifying module for classifying a sensor node that transmits the frame as a value of a Link Adderess field, and transmits the sensor node class using a T, P, and V information bits in a sensor unique transmission period And a tracking module for tracking the sensor information.

The warning data frame unit may further include a frame type module for specifying a warning data frame type; A spare field module for adding sensor information bits to the header of the data; A warning status module for setting a measurement reference value of temperature, pressure and battery level according to an emergency situation; A sensor ID module for storing the product serial number of the sensor; And a payload module for transmitting a value of a sensor having a warning status at a temperature, a pressure, and a battery level according to a predetermined emergency situation; And a second sensor node classifying module for classifying the sensor nodes transmitted through the sensor IDs.

The control unit controls to register a tire position for forming a network between the TPMS sensor node and the monitoring device when the sensor node is reset.

According to the above description, unnecessary RF transmission can be prevented by detecting the running state of the vehicle, and only the necessary measurement data is transmitted according to the situation, thereby restricting the use of unnecessary bits, thereby achieving an optimal TPMS low power operation.

It is possible to satisfy the high reliability according to the occurrence of the emergency situation and to minimize the loss due to the data collision of the sensor node of the other vehicle by distinguishing the sensor node using the sensor ID in case of emergency in contrast to the general data frame .

1 is a view illustrating an unidirectional TPMS communication procedure of a low power TPMS communication system according to an embodiment of the present invention,
FIG. 2 is a configuration diagram of a low power TPMS communication system according to an embodiment of the present invention,
3 is a diagram illustrating a system management frame format of a low power TPMS communication system according to an embodiment of the present invention,
4 is an exemplary diagram illustrating an 8-bit CRC error detector,
5 is a diagram illustrating an exemplary general data frame format of a low power TPMS communication system according to an embodiment of the present invention,
6 is a diagram illustrating an alert data frame format of a low-power TPMS communication system according to an embodiment of the present invention.

Specific features and advantages of the present invention will become more apparent from the following detailed description based on the accompanying drawings. It is to be noted that the detailed description of known functions and constructions related to the present invention is omitted when it is determined that the gist of the present invention may be unnecessarily blurred.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings.

1 is an exemplary diagram illustrating a unidirectional TPMS communication procedure of a low power TPMS communication system according to an embodiment of the present invention. As shown in Fig. 1, in the communication procedure of the unidirectional TPMS for low power, the TPMS sensor node aims to periodically provide the sensor measurement information after power is applied. In order to realize low power, unnecessary RF transmission can be prevented through an algorithm for detecting the running state of the vehicle.

Also, a tire location registration algorithm for forming a network between the TPMS sensor node and the monitoring device is performed when the first sensor node is reset. After network formation, the TPMS sensor node senses the position status through the measured sensor information. According to the crisis state of the sensor node, different frames are transmitted to the monitoring device through RF to provide a service for the monitoring device to detect the tire crash state.

The TPMS consists of a sensor node and a monitoring device. The monitoring device consists of a RF receiver installed in the driver's seat, and a monitoring device including the monitoring device. The sensor node includes a RF transmitter, a pressure sensor, a temperature sensor, and an XZ-directional acceleration sensor, and has a QFN of 7 * 7 * 2.2 mm in consideration of being mounted on a tire. The pressure measurement of the pressure sensor uses a direct method and has one of the measuring ranges of the tire air pressure for each vehicle type. It can have a measuring range of 100 ~ 450kPa for passenger cars and 100 ~ 900kPa for light trucks.

2 is a block diagram of a low power TPMS communication system according to an embodiment of the present invention. 2, the low power TPMS communication system may include a system management frame unit 100, a general data frame unit 200, and an alert data frame unit 300. [

The system management frame unit 100 is a configuration for registering the location of the sensor node. The system management frame unit 100 for performing these functions includes a frame type module 110, a spare field module 120, a link address module 130, a sensor ID module 140, an acceleration X-direction module 150, An acceleration Z-direction module 160, and an error detection field module 170.

The frame type module 110 functions to specify a system management frame type. The spare field module 120 performs a function of adding a sensor information bit to the header of the data. The link address module 130 stores the location address of the sensor node. The sensor ID module 140 stores the product serial number of the sensor. The acceleration X-direction module 150 stores the X-direction acceleration value measured in the acceleration sensor module in the TPMS sensor node. The acceleration Z-direction module 160 stores the Z-direction acceleration value measured in the acceleration sensor module in the TPMS sensor node. The error detection field module 170 performs a function for detecting an error in the frame.

The system management frame unit 100 is a system management frame for notifying the location of the sensor node with the location registration of the sensor node, and has a total size of 56 bits as shown in FIG.

3 is a diagram illustrating a system management frame format of a low power TPMS communication system according to an exemplary embodiment of the present invention.

The frame type field in FIG. 3 serves to display the frame unique number so that the monitoring device can divide the frames of the TPMS DLC (Data Link Control) layer. The values of the frame type field are shown in Table 1 below. In the case of the system management frame, the value of the frame type field is defined as '00'.

Table 1 is a table showing the definition of the frame type field.

[Table 1]

And the Link Address is the location address of the sensor node and can be a total of 16 addresses with a size of 4 bits so that the maximum number of tires that a monitoring device can have is 16. The two reserved fields are reserved for future TPMS development so that new information bits can be added to the header. The 32-bit sensor ID is a product serial number that is unique in the world and unique to the production process. The acceleration X-direction is the X-direction acceleration value measured by the acceleration sensor module in the TPMS sensor node. Similarly, the acceleration Z-direction is the Z-direction acceleration value measured by the acceleration sensor module in the TPMS sensor node. The last Frame Check Sequence (FCS) uses CRC detection as a field for detecting frame errors in the monitoring device. The CRC detection method is implemented as shown in FIG. 4, and the polyhedron is expressed by the following equation (1). 4 is an exemplary diagram illustrating an 8-bit CRC error detector.

[Equation 1]

^{y = x 8 + x 5 +} x 4 + 1

The monitoring device identifies the position of the tire through the acceleration sensor value in the system management frame, stores the sensor ID and the link address together, and when receiving the data frame, notifies the sensor node which transmitted the frame through the sensor ID or link address have.

In order to transmit the measured value of the sensor, it can be divided into two frames depending on the situation of the measured value. A general data frame used to transmit measurement values in a normal state, and a warning data frame used to transmit measurement values and warning information in the event of an emergency.

The general data frame unit 200 is a configuration for transmitting sensor measurement values in a steady state. The general data frame unit 200 for performing these functions includes a frame type module 210, a spare field module 220, a link address module 230, a data frame module 240, a first sensor node classification module 250, a tracking module 260, and an error detection field module 270.

The frame type module 210 functions to specify a general data frame type. The spare field module 220 performs a function of adding a sensor information bit to the header of the data. The link address module 230 functions to store the location address of the sensor node. The data frame module 240 functions to transmit only the measurement data using the temperature bit T, the pressure bit P, and the battery level bit V, which represent the frame information. The first sensor node classifying module 250 performs a function of classifying the sensor node that transmitted the corresponding frame as the value of the Link Adderess field. The tracking module 260 performs a function of tracking sensor information transmitted in a sensor unique transmission period using T, P, and V information bits. The error detection field module 270 performs a function for detecting an error of a frame.

5 is a diagram illustrating an exemplary general data frame format of a low power TPMS communication system according to an embodiment of the present invention.

The general data frame has a size of 48 bits, as shown in Fig. For a normal data frame, the value of the frame type field is defined as '01' defined in Table 2. The Link Address field is a location address of the sensor node. The monitoring device can distinguish the sensor node that has transmitted the corresponding data frame through the location address received from the system management frame. The Reserved field is a field that will allow future information bits to be added to the header in conjunction with TPMS development.

Table 2 shows the definitions of the frame information bits.

[Table 2]

In one embodiment of the present invention, only the necessary measurement data is transmitted according to the situation for the low power operation of the TPMS to limit the use of unnecessary bits. To do this, we use the T, P, and V bits that represent frame information.

As shown in Table 2, the T, P, and V bits indicate whether there is a temperature, a pressure, and a battery level value in the payload of the corresponding frame, respectively, so that the length of the payload can be varied. If the T, P, and V bits are '010', the monitoring device can determine that the beginning of the payload is a pressure measurement. On the other hand, in the case of '000', there is no data but the frame is transmitted in the sensor unique transmission period so that the monitoring device can track the sensor frame of the car in order to avoid collision in the interference situation with the other sensor node. In the last Frame Check Sequence (FCS), CRC detection is used to detect frame errors.

The warning data frame unit 300 is a configuration for transmitting sensor measurement values in an emergency. The alert data frame unit 300 for performing these functions includes a frame type module 310, a spare field module 320, an alert status module 330, a sensor ID module 340, a payload module 350, 2 sensor node identification module 360, and an error detection field module 370.

The frame type module 310 functions to designate a warning data frame type. The spare field module 320 performs a function of adding a sensor information bit to the header of the data. The warning status module 330 functions to set a temperature, a pressure, and a battery level measurement reference value according to an emergency situation. The sensor ID module 340 functions to store the product serial number of the sensor. The payload module 350 transmits the value of the sensor in which a warning state occurs at a temperature, a pressure, and a battery level according to a predetermined emergency situation. The second sensor node classifying module 360 distinguishes the sensor nodes transmitted through the sensor IDs. The error detection field module 370 performs a function for detecting an error in the frame.

The warning data frame unit 300 is a frame used for transmitting measurement values and warning information when an emergency occurs, and has a size of 56 bits as shown in FIG.

6 is a diagram illustrating an alert data frame format of a low-power TPMS communication system according to an embodiment of the present invention.

In the case of warning data frames, the value of the frame type field is defined as '10' defined in Table 1. The Reserved field is a field that allows new information bits to be added to the header for future TPMS development.

In FIG. 6, a Warning State field and a payload to which Warning data is transmitted are fields for transmitting a warning state and a state value, respectively. There are six emergency situations that exist at the temperature, pressure, and battery level that can be judged by the sensor measurement algorithm, as shown in Table 3. The payload also contains the value of the sensor where the alert condition occurred.

[Table 3]

Table 3 shows the warning status and data values for each state.

Unlike the general data frame, the warning data frame used in the emergency situation should minimize the loss due to collision with the sensor node data of the other position having the same location address. For this reason, unlike the general data frame that distinguishes the sensor node that transmitted the frame by the value of the Link Address field, the warning data frame allows the sensor node transmitted through the sensor ID to be distinguished.

Since the sensor ID occupies more bits than the link address, it is inefficient in terms of low power operation of the TPMS. However, in case of emergency, the sensor ID is used because it requires high reliability in system. In the last FCS, CRC detection is used to detect errors in the frame.

The controller 400 detects the running state of the vehicle and controls only the measurement data to be transmitted using the T, P, and V bits indicating the frame information. The control unit 400 controls the TPMS sensor node and the monitoring device And to register the tire position.

100: system management frame unit 110: frame type module
120: spare field module 130: link address module
140: Sensor ID module 150: Acceleration X-direction module
160: Acceleration Z-direction module 170: Error detection field module
200: general data frame unit 210: frame type module
220: spare field module 230: link address module
240: Data frame module 250: First sensor node classification module
260: tracking module 270: error detection field module
300: warning data frame unit 310: frame type module
320: Spare field module 330: Warning state module
340: Sensor ID module 350: Payload module
360: second sensor node classifying module 370: error detecting field module
400:

Claims (9)

A low power TPMS communication system including a sensor node and a monitoring device,
A system management frame unit for registering the location of the sensor node;
A general data frame unit for transmitting sensor measurement values of the sensor node to the monitoring device;
And an alarm data frame unit for transmitting alarm information together with a sensor measurement value that has reached a warning status in comparison with a predetermined alarm criterion,
And a controller for detecting the running state of the vehicle and transmitting only measurement data using T, P, and V bits indicating frame information.
The method according to claim 1,
The system management frame unit includes:
A frame type module for specifying a system management frame type;
A spare field module for adding sensor information bits to the header of the data;
A link address module for storing a location address of the sensor node;
A sensor ID module for storing the product serial number of the sensor;
An acceleration X-direction module for storing an X-direction acceleration value measured by the acceleration sensor module in the TPMS sensor node; And
And an acceleration Z-direction module for storing an acceleration value measured in the Z-direction measured by the acceleration sensor module.
The method according to claim 1,
Wherein the system management frame unit, the general data frame unit, and the warning data frame unit each include an error detection field module for detecting an error of a frame.
The method according to claim 1,
The general data frame unit includes:
A frame type module for specifying a general data frame type;
A spare field module for adding sensor information bits to the header of the data;
A link address module for storing a location address of the sensor node; And
And a data frame module for transmitting only measurement data using a temperature bit (T), a pressure bit (P), and a battery level bit (V) representing frame information.
The method according to claim 1,
Wherein the general data frame unit includes a first sensor node classifying module for classifying a sensor node that has transmitted a corresponding frame as a value of a Link Adderess field.
The method according to claim 1,
Wherein the general data frame unit further comprises a tracking module for tracking the sensor information transmitted in the sensor unique transmission period using the T, P, and V information bits.
The method according to claim 1,
The warning data frame unit includes:
A frame type module for specifying a warning data frame type;
A spare field module for adding sensor information bits to the header of the data;
A warning status module for setting a measurement reference value of temperature, pressure and battery level according to an emergency situation;
A sensor ID module for storing the product serial number of the sensor; And
And a payload module for transmitting a value of a sensor in which a warning state occurs at a temperature, a pressure, and a battery level according to a predetermined emergency situation.
The method according to claim 1,
Wherein the warning data frame unit comprises a second sensor node classifying module for classifying the sensor nodes transmitted through the sensor IDs.
The method according to claim 1,
Wherein the control unit controls to register a tire position for forming a network between the TPMS sensor node and the monitoring device at the time of resetting the sensor node.

Images