TECHNICAL FIELD

The disclosure relates to a tire monitoring system for determining a tire status and/or a tire-to- ground interface status.

BACKGROUND

Modern smart cars use multiple sensors and cameras to monitor the surrounding 360-degree scenery in order to avoid collisions and to provide self-driving or auto-pilot capability.

Devices and systems used comprise global positioning systems (GPS) used to determine the position of the vehicle, ultrasonic sensors to measure the position of objects close to the vehicle, odometry sensors to improve GPS information, lidar and radar used to monitor the surroundings such as the road, vehicles, and pedestrians, as well as video cameras for monitoring the road, vehicles, and pedestrians, and to read traffic lights.

However, current sensor-based on-board vehicle monitoring systems do not provide sufficient information on weather-related conditions such as snow, mud, or ice on the road surface, or take road curvature sufficiently into account.

Hence, there is a need for an improved tire monitoring system.

SUMMARY

It is an object to provide an improved tire monitoring system. The foregoing and other objects are achieved by the features of the independent claim. Further implementation forms are apparent from the dependent claims, the description, and the figures.

According to a first aspect, there is provided a tire monitoring system for determining a tire status and/or a tire-to-ground interface status, the tire monitoring system comprising a hardware unit, configured to be fixed to a rim of a wheel provided with a tire, and at least one light guide configured to be embedded in the tire and extend from an interior surface of the tire at least partially towards an exterior surface of the tire, the hardware unit comprising a contactless sensing arrangement configured to detect electromagnetic radiation within an interior of the tire, the tire status and/or the tire-to-ground interface status being determined at least partially based on the detected electromagnetic radiation.

Such a system provides critical information on road and weather conditions as well as on the curvature of the road. It allows the interaction between tires and road surface, in particular considering acceleration and breaking, to be monitored. This real-time monitoring system can analyze the tire and road conditions in several ways, e.g. by measuring tire angle against the road, thus the tread contact area coverage, monitoring the external tread height, monitoring internal sectional profile changes of the tire against load conditions, and measuring contact area distance from the rotating shaft. These critical parameters can be used by the vehicle central processing unit (CPU) to predict the vehicle’s behavior and prevent traction-based accidents. The present invention in particular improves road safety for self-driving vehicles.

In a possible implementation form of the first aspect, the hardware unit further comprises at least one of a first processing unit configured to determine the tire status and/or the tire-to- ground interface status based on information detected by the contactless sensing arrangement and/or a contact-based sensing arrangement; a transmitting unit configured to transmit information detected by the contactless sensing arrangement and/or the contact-based sensing arrangement to a second processing unit configured to determine the tire status and/or the tire- to-ground interface status based on the transmitted information, and a power supply unit at least partially comprised within the hardware unit. This increases flexibility since it allows the system to be either independent of the vehicle CPU or to take advantage of the vehicle CPU computational power.

In a further possible implementation form of the first aspect, the tire monitoring system is configured to determine the tire status and/or tire-to-ground interface at least once per wheel revolution, allowing the tire to be monitored sufficiently often to continuously provide characteristic information.

In a further possible implementation form of the first aspect, the tire monitoring system is configured to determine the tire status of a loaded section of the tire and/or an unloaded section of the tire, providing maximum flexibility to the system. In a further possible implementation form of the first aspect, the power supply unit comprises a rotary connector configured to be fixed to the rim and a non-rotary connector configured to be fixed to a non-rotating part of the vehicle, facilitating a simple solution for providing power to the system.

In a further possible implementation form of the first aspect, the power supply unit comprises a plurality of coils configured to be fixed to the rim and a plurality of magnets configured to be fixed to a non-rotating part of the vehicle facilitating a self-powering tire monitoring system.

In a further possible implementation form of the first aspect, the contactless sensing arrangement comprises an optical arrangement and/or a level sensing arrangement, allowing a range of external and internal tire conditions to be monitored.

In a further possible implementation form of the first aspect, the optical arrangement comprises an infrared transmitter and the optical arrangement is configured to detect electromagnetic radiation within a visible spectrum and an infrared spectrum, allowing electromagnetic radiation to be used for detecting both external and internal tire conditions.

In a further possible implementation form of the first aspect, the optical arrangement is configured to detect electromagnetic radiation emitted by the infrared transmitter and reflected by the interior surface of the tire, allowing the shape and condition of an interior tire section to be monitored.

In a further possible implementation form of the first aspect, the optical arrangement comprises a first optical unit configured to detect electromagnetic radiation within the visible spectrum and a second optical unit configured to detect electromagnetic radiation within the infrared spectrum. This allows the internal profile of the tire to be monitored, indicating tread contact area coverage, vehicle overload, and more.

In a further possible implementation form of the first aspect, the optical arrangement comprises an optical unit configured to detect electromagnetic radiation within the visible spectrum and an infrared filter configured to allow the optical unit to detect electromagnetic radiation within the infrared spectrum, providing similar capabilities while requiring fewer components taking up less space and having low weight. In a further possible implementation form of the first aspect, one end of the light guide is exposed when the tire has been worn down by a predefined amount such that the light guide extends from the exterior surface of the tire to the interior surface of the tire. This allows the wear of the tire to be monitored, improving safety since the condition of the tire is proportional to the grip on the road and the acceleration and braking capabilities of the vehicle.

In a further possible implementation form of the first aspect, the light guide comprises a material allowing electromagnetic radiation to propagate from an exterior of the tire into the interior of the tire and from the interior of the tire to the exterior of the tire, facilitating a simple and cost- effective component easy to arrange within a tire.

In a further possible implementation form of the first aspect, the light guide is an optomechanical element, a section of which is arranged adjacent the interior surface of the tire, facilitating a simple and cheap element that can be securely embedded within the tire.

In a further possible implementation form of the first aspect, the contact-based sensing arrangement is configured to extend from the interior surface of the tire to the exterior surface of the tire, the contact-based sensing arrangement comprising electrodes configured to short- circuit when in contact with water adjacent the exterior surface. This allows the system to detect, in real-time, when the road is humid due to, for example, water, snow, or ice.

In a further possible implementation form of the first aspect, the contact-based sensing arrangement comprises two electrodes, each electrode being arranged within one light guide and the electrodes being electrically interconnected in the interior of the tire. This allows the contact-based sensing arrangement to be partially arranged within the contactless sensing arrangement.

In a further possible implementation form of the first aspect, the level sensing arrangement comprises a gyroscope and/or a plurality of acceleration sensors. This allows the angular orientation of the tire to be detected and, in turn, the tire contact area towards the road to be determined. According to a second aspect, there is provided a vehicle structure comprising a vehicle central processing unit and a plurality of wheels, each wheel being provided with a tire and the tire monitoring system according to the above, each wheel being provided with one hardware unit of the tire monitoring system and a tire of each wheel being provided with at least one light guide of the tire monitoring system.

Such a structure allows critical information on road and weather conditions as well as on the curvature of the road to be provided and accounted for. It allows the interaction between tires and road surface, in particular considering acceleration and breaking, to be monitored. These critical parameters can be used by the vehicle central processing unit (CPU) to predict the vehicle’s behavior and prevent traction-based accidents. The present invention in particular improves road safety for self-driving vehicles.

In a possible implementation form of the second aspect, each hardware unit comprises a processing unit, each processing unit being configured to determine a tire status and/or a tire- to-ground interface status of one tire; and/or each hardware unit comprises a transmitting unit configured to transmit information detected by the tire monitoring system to the vehicle central processing unit, the vehicle central processing unit being configured to determine the tire status and/or the tire-to-ground interface status of all tires. This increases the flexibility of the solution since it allows the system to be either independent of the vehicle CPU or to take advantage of the vehicle CPU computational power.

These and other aspects will be apparent from the embodiments described below.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following detailed portion of the present disclosure, the aspects, embodiments, and implementations will be explained in more detail with reference to the example embodiments shown in the drawings, in which:

Fig. 1 shows an illustration of a vehicle comprising a vehicle system in accordance with an example of the embodiments of the disclosure;

Figs. 2a to 2c show cross-sectional views of a wheel comprising a tire, illustrating dry conditions on a straight road, dry conditions on a curved road, and wet conditions on a curved road, respectively; Fig. 3a shows a cross-sectional view of a wheel comprising a tire and a tire monitoring system in accordance with an example of the embodiments of the disclosure;

Fig. 3b shows a cross-sectional view of a wheel comprising a tire and a tire monitoring system in accordance with a further example of the embodiments of the disclosure;

Fig. 4a shows a schematic illustration of a hardware unit of a tire monitoring system in accordance with an example of the embodiments of the disclosure;

Fig. 4b shows a schematic illustration of a hardware unit of a tire monitoring system in accordance with a further example of the embodiments of the disclosure;

Fig. 5 shows a cross-sectional view of a wheel comprising a tire and a tire monitoring system in accordance with an example of the embodiments of the disclosure;

Figs. 6a and 6b show cross-sectional views of a wheel comprising a tire and a tire monitoring system in accordance with an example of the embodiments of the disclosure, illustrating dry conditions on a curved road and wet conditions on a curved road, respectively;

Figs. 7a to 7c show cross-sectional views of a wheel comprising a tire and a tire monitoring system in accordance with an example of the embodiments of the disclosure, illustrating the amount of wear of the tire and the detection of different levels of wear;

Figs. 8a to 8c show cross-sectional views of a wheel comprising a tire and a tire monitoring system in accordance with an example of the embodiments of the disclosure, illustrating different tire geometries which may arise on a straight road, in a curve, and when tire pressure is low or the vehicle is heavily loaded, respectively; and

Fig. 9 shows a cross-sectional view of a wheel comprising a tire and a tire monitoring system in accordance with an example of the embodiments of the disclosure, illustrating a change in angular direction of the tire relative to the wheel rotation axis.

DETAILED DESCRIPTION

The present invention relates to a tire monitoring system 1 for determining a tire status and/or a tire-to-ground interface status, the tire monitoring system 1 comprising a hardware unit 2, configured to be fixed to a rim 3 of a wheel 22 provided with a tire 4, and at least one light guide 5 configured to be embedded in the tire 4 and extend from an interior surface 4a of the tire 4 at least partially towards an exterior surface 4b of the tire 4, the hardware unit 2 comprising a contactless sensing arrangement 6 configured to detect electromagnetic radiation within an interior of the tire 4, the tire status and/or the tire-to-ground interface status being determined at least partially based on the detected electromagnetic radiation. Fig. 5 illustrates a tire monitoring system 1 for determining a tire status and/or a tire-to-ground interface status. Tire status may include parameters such as tire tread depth, unevenness of tire wear, outer tire section profile, inner tire section profile, relative angular orientation due to camber, tire pressure, and internal thermal conditions. For example, Fig. 7a illustrates a tire without wear, Fig. 7b illustrates a tire with some wear, and Fig. 7c illustrates a tire with maximum wear. Tire-to-ground interface status may include parameters such as tire road contact area, road surface conditions, and external thermal conditions. For example, Fig. 2a illustrates dry conditions on a straight road, Fig. 2b illustrates dry conditions on a curved road, and Fig. 2c illustrates wet conditions on a curved road.

The tire status and the tire-to-ground interface status are determined at least partially based on detected electromagnetic radiation. The determination may be made by a simple process such as mere sensing of the presence of any electromagnetic radiation within the interior of the tire 4. The determination may also be made using a more complex process including different calculations, where the level of electromagnetic radiation, within one or several areas of the interior of the tire 4, is taken into account. Furthermore, tire-specific data may be uploaded to the tire monitoring system 1 or the vehicle CPU 10 from the tire manufacturer, the data being used in any calculations and predictions made.

The tire monitoring system 1 may be configured to determine the tire status and/or tire-to- ground interface at least once per wheel revolution. The tire status and/or tire-to-ground interface may be determined once per wheel revolution, for example at a point where a specific peripheral area of the tire is in contact with the road. The tire status and/or tire-to-ground interface may be determined twice per wheel revolution, for example at a first point where a specific peripheral area of the tire is in contact with the road and at a second point where the specific peripheral area of the tire is not in contact with the road. The tire status and/or tire-to- ground interface may also be determined continuously as the wheel rotates. The tire monitoring system 1 may, in other words, be configured to determine the tire status of a loaded section of the tire 4 and/or an unloaded section of the tire 4. A loaded section of the tire is a section that is in contact with the road and therefore carries the weight of the vehicle. An unloaded section of the tire is a section that is not in contact with the road and therefore does not carry any vehicle weight, i.e. the main part of the tire at any given moment. The tire monitoring system 1 comprises a hardware unit 2 configured to be fixed to a rim 3 of a wheel 22 provided with a tire 4, as illustrated in Fig. 5. The hardware unit 2 comprises a contactless sensing arrangement 6 configured to detect electromagnetic radiation within an interior of the tire 4.

The hardware unit 2 may further comprise one or several of a first processing unit 7, a transmitting unit 9, shown in Figs. 4a and 4b, and a power supply unit 11, shown in Figs. 3a and 3b.

The first processing unit 7 is configured to determine the tire status and/or the tire-to-ground interface status based on information detected by the contactless sensing arrangement 6 and/or a contact-based sensing arrangement 8.

The transmitting unit 9 is configured to transmit information detected by the contactless sensing arrangement 6 and/or the contact-based sensing arrangement 8 to a second processing unit 10 configured to determine the tire status and/or the tire-to-ground interface status based on the transmitted information. The transmitting unit 9 may comprise a low-power wireless communication system such as a Bluetooth or Wi-Fi transmitter, or may comprise a cable connection.

The power supply unit 11 is at least partially comprised within the hardware unit 2. The power supply unit 11 may comprise a rechargeable electricity storage device such as a battery, or be configured to power the system directly.

As shown in Fig. 3a, the power supply unit 11 may comprise a rotary connector 12 configured to be fixed to the rim 3 and a non-rotary connector 13 configured to be fixed to a non-rotating part of the vehicle. The non-rotary connector 13 may be connected via cables to a power supply arranged in the vehicle.

As shown in Fig. 3b, the power supply unit 11 may comprise a plurality of coils 14 configured to be fixed to the rim 3 and a plurality of magnets 15 configured to be fixed to a non-rotating part of the vehicle. This allows a self-powering system generating power via electromagnetic induction. The tire monitoring system 1 also comprises at least one light guide 5 configured to be embedded in the tire 4 and extend from an interior surface 4a of the tire 4 at least partially towards an exterior surface 4b of the tire 4. The light guide 5, or probe 5, penetrates the tire 4 in a direction from the interior surface 4a of the tire 4 towards the exterior surface 4b, i.e. when the tire is new, and not worn, the light guide 5 does not reach the exterior surface 4b as illustrated in Fig. 7a. When the tire is somewhat worn, for example at the periphery of the tire, the rubber of the tire has been degraded such that the end of one light guide 5 is exposed at the exterior surface 4b as illustrated in Fig. 7b. Similarly, when the tire is fully worn, the rubber across the entire tire contact area has been degraded such that the ends of all light guides 5 are exposed at the exterior surface 4b as illustrated in Fig. 7c. Monitoring the wear of the tire improves safety since the condition of the tire is proportional to the grip on the road and the acceleration and braking capabilities of the vehicle.

One end of the light guide 5 may be exposed when the tire 4 has been worn down by a predefined amount such that the light guide 5 extends all the way from the exterior surface 4b of the tire 4 to the interior surface 4a of the tire 4. The light guides 5 may have different lengths such that their respective ends are exposed after different amounts of wear, as illustrated in Fig. 5 where the three light guides 5 all have different lengths.

The light guide 5 may be transparent, i.e. comprise a material allowing electromagnetic radiation to propagate from the exterior of the tire 4 into the interior of the tire 4 where, in turn, the electromagnetic radiation can be detected by the contactless sensing arrangement 6. Correspondingly, electromagnetic radiation can propagate from the interior of the tire 4 to the exterior of the tire 4. The material may be a transparent plastic, e.g. polyurethane.

The light guide 5 is an optomechanical element, a section of which is arranged adjacent the interior surface 4a of the tire 4. For example, the lightguide may have the shape of a bolt or nail, the head of the bolt or nail being in abutment with the interior surface 4a of the tire 4. The optomechanical element may also be a self-locking element locked into place by friction or by means of the internal tire pressure.

The contactless sensing arrangement 6 may comprise an optical arrangement 16 and/or a level sensing arrangement 17. As illustrated in Fig. 9, the level sensing arrangement 17 may comprise a gyroscope and/or a plurality of acceleration sensors used for detecting the angular orientation of the tire, providing data for analysis of the tire contact area against the road under dynamic deformations due to the shape and angle of the road and/or due to effects of the vehicle suspension.

The optical arrangement 16 may comprise an infrared transmitter 18 and the optical arrangement 16 may be configured to detect electromagnetic radiation within a visible spectrum as well as within and an infrared spectrum. The optical arrangement 16 may be arranged to face the interior surface of the tire 4. The optical arrangement 16 may be configured to detect electromagnetic radiation which is emitted by the infrared transmitter 18 and reflected back, by the interior surface 4a of the tire 4, towards the optical arrangement 16. This allows the internal profile of the tire to be monitored, indicating tread contact area coverage which can be used to determine overload or whether the vehicle is going through a curve. Fig. 8a illustrates a normal tire geometry on a straight road and Fig. 8b illustrates a corresponding tire geometry in a curve, where the tire contact area is reduced. Fig. 8c illustrates heavy load or low tire pressure.

The optical arrangement 16 may comprise a first optical unit 19 configured to detect electromagnetic radiation within the visible spectrum and a second optical unit 20 configured to detect electromagnetic radiation within the infrared spectrum, as illustrated in Fig. 4a.

The optical arrangement 16 may also comprise an optical unit 19 configured to detect electromagnetic radiation within the visible spectrum and an infrared filter 21 configured to allow the optical unit 19 to detect electromagnetic radiation within the infrared spectrum, as illustrated in Fig. 4b.

When there is no wear on the tire, as illustrated in Fig. 7a, no electromagnetic radiation can travel through the light guide 5 from the exterior to the interior of the tire 4, and therefore the optical unit 19 cannot detect electromagnetic radiation within the visible spectrum. Correspondingly, where the tire is worn such that one light guide 5 is exposed towards the exterior, electromagnetic radiation within the visible spectrum will travel through the light guide 5 from the exterior to the interior of the tire and will, subsequently, be detected by the optical unit 19. This indicates that the wearing of the tire has begun, as illustrated in Fig. 7b. When all light guides 5 are exposed towards the exterior, as shown in Fig. 7c, this indicates tire end of life. The optical unit 19 may be a black and white camera or a color camera. The optical unit 20 may be a structured light camera.

The contactless sensing arrangement 6 may furthermore comprise pressure-based sensing elements or sound-based sensing elements.

The contact-based sensing arrangement 8 may comprise capacitive sensor elements. The contact-based sensing arrangement 8, shown in Fig. 5, may be configured to extend from the interior surface 4a of the tire 4 to the exterior surface 4b of the tire 4, the contact-based sensing arrangement 8 comprising electrodes 8a configured to short-circuit when in contact with water adjacent the exterior surface 4b. The contact-based sensing arrangement 8 is configured such that it does not provide any signal in dry conditions.

The electrodes 8a of the contact-based sensing arrangement 8 may be arranged completely independently of the light guides, as illustrated in Fig. 6a, showing a dry road, and Fig. 6b, showing a wet road. The contact-based sensing arrangement 8 may also comprise two electrodes 8a, each electrode 8a being arranged within one light guide 5 (not shown) and the electrodes 8a being electrically interconnected in the interior of the tire 4. The electrodes 8a may comprise any suitable conductive material such as a relatively hardwearing metal.

Additionally, the tire monitoring system 1 may comprise tire pressure monitors and/or spectral or thermal cameras detecting material properties and temperature of objects in the surrounding. Furthermore, the tire monitoring system 1 may comprise solutions for tracking the external profile of the road, such as lidar, infrared cameras with diffractive illumination elements, or time-of-flight cameras.

The present invention also relates to a vehicle structure 23 such as a car or a truck, illustrated in Fig. 1. The vehicle structure comprises a vehicle central processing unit 10 and a plurality of wheels 22, each wheel 22 being provided with a tire 4 and the tire monitoring system 1 described above. Each wheel 22 is provided with one hardware unit 2 of the tire monitoring system 1 and the tire 4 of each wheel 22 is provided with at least one light guide 5 of the tire monitoring system 1. Each hardware unit 2 may comprise a processing unit 7 and/or a transmitting unit 9. Each processing unit 7 is configured to determine the tire status and/or tire-to-ground interface status of one tire 4. Each transmitting unit 9 is configured to transmit information detected by the tire monitoring system 1 to the vehicle central processing unit 10, the vehicle central processing unit 10 in turn being configured to determine the tire status and/or the tire-to-ground interface status of all tires 4.

The various aspects and implementations have been described in conjunction with various embodiments herein. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art when practicing the claimed subject-matter, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.

The reference signs used in the claims shall not be construed as limiting the scope. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this disclosure. As used in the description, the terms “horizontal”, “vertical”, “left”, “right”, “up” and “down”, as well as adjectival and adverbial derivatives thereof (e.g., “horizontally”, “rightwardly”, “upwardly”, etc.), simply refer to the orientation of the illustrated structure as the particular drawing figure faces the reader. Similarly, the terms “inwardly” and “outwardly” generally refer to the orientation of a surface relative to its axis of elongation, or axis of rotation, as appropriate.