WO2021106010A1

WO2021106010A1 - Determining contact patch angle of tyres

Info

Publication number: WO2021106010A1
Application number: PCT/IN2020/050932
Authority: WO
Inventors: Jacob George; Sandip Patel; Dinesh GANESHAN; Praveen Sharma; Sharad GOYAL
Original assignee: Ceat Limited
Priority date: 2019-11-26
Filing date: 2020-11-05
Publication date: 2021-06-03

Abstract

Techniques for determining contact patch length is described. A first number of data points is detected. The first number of data points is a total number of data points recorded in a full rotation of a tyre (104), and wherein each of the data points is a measurement of a tyre parameter recorded by a sensing unit (108). A second number of data points out of the first number of data points is ascertained, wherein the second number of data points is a total number of data points recorded by the sensing unit (108) when an area of the tyre containing the sensing unit comes in contact with a surface on which the tyre is rotating. Contact patch angle is computed based on the first and the second number of data points. The contact patch angle is further used to determine the contact patch length of the tyre.

Description

DETERMINING CONTACT PATCH ANGLE OF TYRES

TECHNICAL FIELD

[0001] The present subject matter relates, in general, to monitoring tyre of a vehicle, in particular, to determining a contact patch length of the tyre of the vehicle.

BACKGROUND

[0002] Tyres play an important role in dynamics of a vehicle. Among other things, they help in providing lateral, longitudinal & radial forces to the vehicle required for tracking, steering, traction and providing stability to the vehicle. Therefore, various parameters of the tyre are monitored so that the corrective measures, if required, may be taken.

[0003] Generally, the various parameters of a tyre are measured by sensors installed on the tyre. These parameters may include but not limited to tire pressure, tire positioning w.r.t longitudinal, radial and lateral (X, Y, Z axis) directions, internal temperature of the tire, internal humidity of the tire, angular acceleration and deceleration of the tire, load on the tire, speed of rotation of the tire, distance travelled by the tire, traction of the tire, various types of failure of the tire, and events, such as wear, breaking acceleration and deceleration etc., of the tire. To determine and measure the various parameters of the tyre, the contact patch length of the tyre needs to be determined. The contact patch length of the tyre is an area of the tyre that comes in contact with a surface on which the tyre is moving. The sensors come within the area of the contact patch once every rotation of the tyre. Determination of the contact patch length of the tyre in an accurate manner is desirable in order to measure the various parameters of the tyre of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference the same elements.

[0005] Figure 1 illustrates an environment 100 for determining contact patch angle of a tyre, in accordance with an example implementation of the present subject matter;

[0006] Figures 2 illustrates a schematic diagram of system for determining contact patch angle of a tyre, in accordance with another example of the present subject matter.

[0007] Figure 3 illustrates examples of data points as recorded by a sensing unit.

[0008] Figure 4 describes a method of determining contact patch angle of a tyre, in an example implementation of the present subject matter.

DETAILED DESCRIPTION

[0009] Contact patch length is used for determining and monitoring parameters of the tyre. For example, the length of the contact patch may indicate the loading of the vehicle. The pressure exerted on the tyres may be accurately determined by monitoring the contact patch length of the tyre. The contact patch length of the tyre may be determined by measuring a contact patch angle of the tyre. The contact patch angle is an angle formed at a center of the tyre by an area of the tyre which is in contact with the surface on which the tyre is rotating. [0010] Conventional techniques are often inaccurate in measuring the contact patch angle of the tyre. Generally, leading & trailing edges of the area of the tyre that is in contact with the surface during movement of the tyre are determined to estimate the contact patch length of the tyre. However, because of varying speed of rotation of the tyre, such edges may be difficult to identify, especially at high speeds. Accordingly, conventional techniques do not offer precise measurement of the contact patch length of the tyre.

[0011] According to an example implementation of the present subject matter, techniques for accurately measuring the contact patch angle and in turn the contact patch length of the tyre is described. The contact patch angle is an angle formed at a center of the tyre by an area of the tyre which is in contact with the surface on which the tyre is rotating.

[0012] According to the present subject matter, a first number of data points is detected by a sensing unit located on a tyre of the vehicle. The first number of data points is a total number of data points recorded in a full rotation of the tyre. Each of the data point is a measurement of a tyre parameter recorded by the sensing unit. Further, a second number of data points out of the first number of data points is ascertained. The second number of data points is a total number of data points recorded by the sensing unit when an area of the tyre containing the sensing unit comes in contact with a surface on which the tyre is rotating. Thereafter, based on the first number of data points and the second number of data points, a contact patch angle of the tyre is computed.

[0013] Thus, according to the present subject matter, after the contact patch angle of the tyre is determined, the contact patch angle of the tyre can be used to determine the contact patch length of the tyre.. The contact patch length of the tyre may further be used to determine parameters of the tyre, such as tyre load, and speed. As described earlier, the contact patch length is a length of the tyre which is in contact with the surface at an instance of time. The accurate determination of the contact patch angle and contact patch length results in accurate measurement of the parameters of the tyre. The contact patch length is also used in various algorithms, such as load determination algorithm, dynamic radius determination algorithm etc. In operation of the vehicle, these algorithms reduce the overall cost of operation; improve tyre life by measuring load distribution on the tyre; provide for alignment of the tyre; and improve safety by predicting failures, wear and the like of the tyre. Accurate determination of contact patch length directly impacts the accuracy of the results of these algorithms. For example, if contact patch length is not determined correctly, the load determination algorithm may estimate incorrect load on tyre or vehicle.

[0014] It should be noted that the description and the figures merely illustrate the principles of the present subject matter along with examples described herein and, should not be construed as a limitation to the present subject matter. It is thus understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and implementations of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.

[0015] Figure 1 illustrates an environment 100 for determining a contact patch angle 102 of tyre 104, in accordance with an example implementation of the present subject matter. The environment 100 comprises a system 106 coupled with the sensing unit 108that is mounted within the tyre 104.

[0016] The system 106 comprises a data point determining engine 110 and a contact patch monitoring engine 112. The data point determining engine 110 determines a first number of data points of a tyre of a vehicle. The first number of data points may be measured by the sensing unit 108 in a full rotation of the tyre 104 and the measurements may be provided to the data point determining engine 110. The first number of data points is a measurement of a tyre parameter recorded by the sensing unit 108. The tyre parameter can be recorded through an appropriate sensor. In an example, the data points may be a measure of acceleration profiles of the tyre 104 at regular intervals. The acceleration profiles of the tyre 104 may be measured by the sensing unit 108. In an example, the sensing unit may include a accelerometer for such measurement. In an example, there may be 100 data points in a full rotation of the tyre 104.

[0017] Further, the data point determining engine 110 ascertain a second number of data points out of the first number of data points. The second number of data points is a total number of data points recorded by the sensing unit 108 when an area of the tyre 104 containing the sensing unit 108 comes in contact with a surface on which the tyre 104 is rotating.

[0018] After the first number of data points and the second number of data points are determined, the contact patch monitoring engine 112 determines the contact patch angle 102 of the tyre 104. The contact patch angle 102 is formed at the center of the tyre 104 by an area of the tyre which is in contact with the surface on which the tyre is rotating. The contact patch encloses a contact patch length 114 of the tyre 104.

[0019] Figures 2 illustrates the system 106, in accordance with an example of the present subject matter.

[0020] The system 106, among other things, includes a memory 202 and engine(s) 206. The memory 202 may include any computer-readable medium including, for example, volatile memory (e.g., RAM), and/or non-volatile memory (e.g., erasable programmable read-only memory (EPROM), flash memory, etc.). [0021] The system 106 is coupled to the sensing unit 108. In an example, the sensing unit 108 may comprise sensors, such as gyroscope, accelerometers, pressure sensors, temperature sensors etc. In an example, the sensing unit 108 may comprise an enclosure mounted on the tyre and the sensors may be mounted in the enclosure in the enclosure using a poke-yoke arrangement. For example, the sensors may be mounted on a sensor assembly which may further be mounted in the enclosure. The sensor assembly may have two or more fins which may couple with grooves in the enclosure of the sensor assembly. In an example, the two or more fins may have different shape such that a specific fin fits into a specific groove. Thus, this arrangement ensures that the sensor is fitted in the sensor assembly in right orientation.

[0022] The engine(s) 206 may be implemented as a combination of hardware and programming (for example, programmable instructions) to implement certain functionalities of the engine(s) 206, such determining contact patch angle of the tyre. In examples described herein, such combinations of hardware and programming may be implemented in several different ways. For example, the programming for the engine(s) 206 may be processor executable instructions stored on a non-transitory machine-readable storage medium and the hardware for the engine(s) 206 may include a processing resource (for example, implemented as either a single processor or a combination of multiple processors), to execute such instructions. In the present examples, the machine-readable storage medium may store instructions that, when executed by the processing resource, implement engine(s) 206. In such examples, the system 106 may include a machine- readable storage medium storing the instructions and the processing resource to execute the instructions, or the machine-readable storage medium may be separate but accessible to the system 106 and the processing resource. In other examples, engine(s) 206 may be implemented by electronic circuitry. In an example, in addition to a data point determining engine 110, a contact patch monitoring engine 112, a load determination engine 208, and the engine(s) 206 may also comprise other engine(s) 210 that supplement functions of the system 106.

[0023] Data 212 serves, amongst other things, as a repository for storing data that may be fetched, processed, received, or generated by the engine(s) 206. The data 212 comprises other data 214 corresponding to the other engine(s) 210. In the illustrated example, the data 212 of the system 106 also comprises data points data 216 and contact patch data 218.

[0024] In operation, the data point determining engine 110 determines the first number data points of the tyre 104 of the vehicle. As explained earlier, the first number of data points are measurements of tyre parameter as recoded by the sensing unit 108. In an example, the parameter may be speed or acceleration of the tyre and pressure exerted on the tyre 104. In an example, acceleration forces acting on the tyre may be measured through accelerometer. Other parameters such as temperature may be measured through corresponding sensor such as temperature sensor. Further, the data point determining engine 110 determines the second number of data points out of the first number of data points. The second number of data points are the number of data points recorded by the sensing unit 108 when a part or area of the tyre 104 containing the sensing unit 108 comes in contact with a surface on which the tyre is rotating. In an example, the first number of data points may be 100 while the second number of data points may be 10.

[0025] After the first number of data points and the second number of data points are determined, the contact patch monitoring engine 112 determines a contact patch angle based on the first number of data points and the second number of data points. As described earlier, the contact patch angle is an angle formed by an area of the tyre which is in contact with the surface on which the tyre is rotating with respect to the center of the tyre. To determine the contact patch angle, the contact patch monitoring engine 112 divides 360 degrees by the first number of data points and thereafter multiply the result with the second number of data points.

[0026] As understood, the first number of data points is recorded for a full rotation of the tyre, i.e., for 360 degrees of rotation of the tyre 104. In other words, the first number of data points is recorded for whole circumference (area) of the tyre 104. Dividing 360 degree by the first number of data points gives degree of tyre per number of data points. Thereafter, multiplying the second number of data points by degree of tyre per number of data points gives the contact patch angle of the tyre as the second number of data points corresponds to the measurements recorded for the area of tyre which is in contact with the surface. [0027] Considering an example, if the first number of data points is 100 and the second number of data points is 10, the contact patch angle is determined as below:

Degree per number of data points=360/(100) first number of data points.

Contact patch angle= 3.6 (Degree per number of data points) x 10(second number of data points)

= 36 degrees.

[0028] In an example, the number of first data points and the number of second data points may be stored in the data points data 216. The contact patch monitoring engine 112 may access the data points data 216 to retrieve the first number of data points and the second number of data points to calculate the contact patch angle. The contact patch angle may be stored in the contact patch data 218.

[0029] The contact patch monitoring engine 112, , based on the contact patch angle, determines a contact patch length of the tyre. The contact patch length is a length of the tyre 104 which is in contact with the surface at an instance of time. In an example, the contact patch monitoring engine 112 divides the total circumferential length of the tyre by 360 degrees to derive length per unit degree. Thereafter, the contact patch monitoring engine 112 multiples the length per unit degree with the contact patch angle to determine the contact patch length of the tyre. The contact patch length may be stored in the contact patch data 218

[0030] As described earlier, the system also comprises the load determination engine. Based on the contact patch length the load determination engine 208 determines a dynamic radius of the tyre of the vehicle. The dynamic radius is a real times radius of a wheel to which the tyre is coupled. The dynamic radius of the wheel is indicative of change in real time radius of the wheel due to applied load on the tyre. In an example, the load determination engine 208 may access the contact patch data 218 to retrieve the contact patch length of the tyre. The larger the contact patch length, the lesser would be the dynamic radius (more load), and the lesser is the contact patch length the larger would be the dynamic radius (less load).

[0031] Figure 3 shows an example of data points recorded by the sensing unit. A contact patch angle of a tyre needs to be determined based on the data points. The data points captured by the sensing unit is shown on graph 302. A plurality of data points 304 between the points 306-1 and 306-2 indicates the first number of data points. Further, data points between the points 306-3 and 306-1 are the second number of data points that are recorded when an area of the tyre containing the sensing unit touches a surface. After, the first number of data points and the second number of data points are determined, the contact patch angle is determined based on the techniques as described above. [0032] Figure 4 describes a method 400 of determining a contact patch angle of a tyre in an example implementation of the present subject matter. Although the method 400 may be implemented in a variety of computing systems which may be coupled with a sensing unit such as sensing unit 108 incorporated in a tyre 104, for the ease of explanation, the present description of the example method 300 is provided in reference to the above-described system 200. The order in which the method 400 is described is not intended to be construed as a limitation, and any number of the described method blocks may be combined in any order to implement the method 400, or an alternative method.

[0033] At block 402, a first number of data points as detected by the sensing unit 108 located on a tyre of a vehicle is determined. In an example, the load determining engine 110 of the system 200 may determine the first number of data points. The first number of data points is a total number of data points recorded in a full rotation of the tyre 104, and wherein each of the data points is a measurement of a tyre parameter recorded by the sensing unit 108. In an example, the tyre parameter may be an acceleration of the tyre, tyre pressure, tyre temperature, load on tyre, angle of the contact patch with centre of the tyre, etc.

[0034] At block 404, the second number of data points is ascertained out of first number of data points. In an example, the load determining engine 110 of the system may ascertain the second number of data points. The second number of data points is a total number of data points recorded by the sensing unit 108 when an area of the tyre containing the sensing unit comes in contact with a surface on which the tyre is rotating. The method thereafter proceeds to block 406.

[0035] At block 406, a contact patch angle is computed based on the first number of the data points and the second number of data points. In an example, the contact patch monitoring engine 112 of the system 200 may compute the contact patch angle of the tyre 104. The contact patch angle is an angle formed at a center of the tyre 104 which encloses an area of the tyre 104 which is in contact with the surface on which the tyre 104 is rotating. Further, based on the contact patch angle, a contact patch length may be determined. The contact patch length is a length of the tyre 104 which is in contact with the surface at an instance of time. In an example, the contact patch monitoring engine 112 may determine the contact patch length of the tyre 104 using the contact patch angle of the tyre 104. The contact patch length may be thereafter used to calculate dynamic radius of the trye. Further, the contact patch length data may be provided to a load determination engine such as load determining engine 208 of the system 200. In an example, the load determination engine may also be contained within an electronic control unit of the vehicle and may use the contact patch length data to calculate the load exerted on the tryes of the vehicle. [0036] Although implementations for measuring contact patch angle and contact patch length of a tyre have been described in a language specific to structural features and/or applications, it is to be understood that the present subject matter is not limited to the specific features or applications described. Rather, the specific features and applications are disclosed as exemplary implementations.

Claims

I/We Claim:

1. A method 400 comprising: determining a first number of data points detected by a sensing unit 108 located on a tyre 104 of a vehicle, wherein the first number of data points is a total number of data points recorded in a full rotation of the tyre, and wherein each of the data points is a measurement of a tyre parameter recorded by the sensing unit 108; ascertaining a second number of data points out of the first number of data points, wherein the second number of data points is a total number of data points recorded by the sensing unit 108 when an area of the tyre 104 containing the sensing unit 108 comes in contact with a surface on which the tyre 104 is rotating; and computing, based on the first number of data points and the second number of data points, a contact patch angle of the tyre 104, the contact patch angle being an angle formed by an area of the tyre 104 in contact with the surface on which the tyre is rotating with respect to the center of the tyre 104.

2. The method as claimed in claim 1, further comprising: determining, based on the contact patch angle, a contact patch length, wherein the contact patch length is a length of the tyre 104 which is in contact with the surface at an instance of time.

3. The method as claimed in claim 1, wherein the tyre parameter is an acceleration of the tyre 104.

4. The method as claimed in claim 2, further comprising: providing the contact patch length to a load determination engine of an electronic control unit of the vehicle.

5. A system 200 comprising: a data point determining engine 110 to: determine a first number of data points of a tyre 104 of a vehicle, wherein the first number of data points are total number of data points recorded in a full rotation of the tyre, by a sensing unit 108 attached to the tyre 104, wherein each of the data points is a measurement of a tyre parameter recorded by the sensing unit 108; ascertain a second number of data points out of the first number of data points, wherein the second number of data points is a total number of data points recorded by the sensing unit 108 when an area of the tyre 104 containing the sensing unit 108 comes in contact with a surface on which the tyre 104 is rotating; and contact patch monitoring engine 112 to: compute, based on the first number of data points and the second number of data points, a contact patch angle of the tyre 104, the contact patch angle being an angle formed by an area of the tyre 104 which is in contact with the surface on which the tyre 104 is rotating with respect to the center of the tyre 104.

6. The system 200 as claimed in claim 5, wherein the tyre parameter is one of a speed of the tyre, and pressure exerted on the tyre.

7. The system 200 as claimed in claim 5, wherein the contact patch monitoring engine 112 is to determine, based on the contact patch angle, a contact patch length, wherein the contact patch length is a length of the tyre 104 which is in contact with the surface at an instance of time.

8. The system 200 as claimed in claim 5, wherein the system 200 further comprises a load determination engine 208 to: determine, based on the contact patch length, a dynamic radius of the tyre 104 of the vehicle, wherein the dynamic radius is a real time radius of a wheel on which the tyre 104 is coupled; and calculate, based on the dynamic radius, a load applied on the tyre 104 of the vehicle.

9. The system 200 as claimed in claim 5, wherein the sensing unit 108 comprises: an enclosure mounted on the tyre 104; and sensors mounted in the enclosure wherein the sensors are mounted in the enclosure in a poke-yoke arrangement.

10. The system 200 as claimed in claim 9, wherein the sensors are at least one of an accelerometer, gyroscope, pressure sensor, and temperature sensor.

IB