Device for determining a property of a tire

Abstract

A computer-implemented method for determining at least an effective rolling radius (Re) of a tire (230) mounted on a heavy vehicle (100) is provided. The method comprises determining (S1) a measured distance between a predefined point (P1) of the vehicle (100) and a ground plane (101) supporting the vehicle (100); determining (S2) a loaded tire radius of a tire of the vehicle (100) based on the measured distance; obtaining (S3) a predetermined relationship between a loaded tire radius and an effective rolling radius of the tire; and determining (S4) the effective rolling radius (Re) of the tire based on the determined loaded tire radius and the predetermined relationship between the loaded tire radius and the effective rolling radius of the tire.

Description

Technical Field

[0001] The present disclosure relates to a method and a control unit for ensuring safe and efficient vehicle motion management of a heavy vehicle. The method is particularly suitable for use with articulated vehicles, such as trucks and semi-trailers comprising multiple vehicle units. However, the invention may also be applied to other types of vehicles, for example, construction equipment and mining vehicles as well as cars. Background Art

[0002] Heavy vehicles (such as trucks and semi-trailer vehicles) are designed to carry heavy loads. Heavy-duty vehicles must be able to start from a standstill, also in uphill conditions, accelerate on various types of road surfaces, and most importantly be able to reduce speed, i.e. brake, at any time in a controlled and reliable manner. It is also important that the vehicle can be operated in an energy-saving manner without unnecessary wear of components. A key property to achieve this function is a set of well-designed tires. Therefore, a lot of work has been done in developing tires for heavy vehicles, wherein well-designed tires provide a combination of high friction and low rolling resistance. Well-designed tires also have a low wear rate, i.e., are mechanically durable and have a long service life.

[0003] Tires play a significant role in determining the behavior and capabilities of a vehicle, and therefore managing the operation of the vehicle. It is therefore beneficial to be able to perform real-time analysis of different tire properties of a vehicle to react quickly to changes in tire and / or road properties.

[0004] US5793285 discloses an apparatus for monitoring tires on a vehicle to detect adverse tire operating conditions by continuously measuring the distance between an associated vehicle axle and the road while the vehicle is operating.

[0005] However, vehicle motion management for heavy vehicles still needs further improvement. Summary of the invention

[0006] An object of the present disclosure is to provide a technique that alleviates or overcomes at least some of the above-mentioned problems. This object is achieved at least in part by a method for determining an effective rolling radius of a tire mounted on a heavy vehicle. The method comprises determining a measured distance between a predefined point of the vehicle and a ground plane supporting the vehicle. The method further comprises determining a loaded tire radius of a tire of the vehicle based at least on the measured distance; obtaining a predetermined relationship between the loaded tire radius and the effective rolling radius of the tire; and determining the effective rolling radius of the tire based on the determined loaded tire radius and the predetermined relationship between the loaded tire radius and the effective rolling radius of the tire. The method provides real-time determination of the effective rolling radius, which is important information for managing the operation of the vehicle. The method also allows tracking of the rolling radius over time, which means that changes in the effective rolling radius due to changes in vehicle operating conditions (such as different loads) will be reflected in the overall vehicle motion management.

[0007] According to various aspects, the predetermined relationship is obtained based on tire design data of the tire obtained from a memory associated with the tire design. Different types of tires may have different properties and may react differently to events such as low road friction, high temperatures, rain, etc. By taking the tire design into account, the relationship between the loaded tire radius and the effective rolling radius of the tire may be more accurately modeled. The data associated with the tire design may, for example, include any of the following: the nominal size of the tire, the structural characteristics of the tire, the chemical composition of the tire, and the history of the tire, such as how long the tire has been used.

[0008] According to various aspects, the predetermined relationship is obtained based on input data from one or more sensors arranged to measure one or more operating parameters of the tire. The sensors can be configured to provide real-time data from the tire, thereby enabling a real-time dynamic determination of the effective rolling radius that reacts quickly to changes in tire properties. Therefore, if the tire properties change, the determination of the effective rolling radius will take this into account.

[0009] According to various aspects, the one or more operating parameters include any of: vehicle speed, wheel rotation speed, tire pressure, tire temperature, tire acceleration, tire strain, tire GPS location, weather, ambient temperature, rain classification data, normal load, slip angle, steering angle, wheel load measurements, axle load measurements, applied torque, and suspension parameters. Having accurate information about one or more of these parameters facilitates accurate determination of the effective rolling radius and facilitates efficient and / or safe vehicle control.

[0010] In some aspects, the loaded tire radius is determined based on the measured distance d1 and load measurements obtained from the suspension system.

[0011] According to various aspects, the predetermined relationship is obtained based on one or more estimated tire parameters, the one or more estimated tire parameters including any of the following: tire wear, tire longitudinal stiffness, tire lateral stiffness, tire rolling resistance, tire peak friction, tire contact patch properties, tire balance properties, and wheel alignment properties. Having accurate information about one or more of these parameters facilitates accurate determination of the effective rolling radius and facilitates efficient and / or safe vehicle control.

[0012] According to various aspects, the measured distance is determined by receiving a radar signal from at least one radar transceiver, the radar signal being directed at a known angle between a vertical plane and a horizontal plane of the heavy vehicle. The measured distance is determined by adjusting the distance measured by the radar signal by compensating for the known angle A1. Radar transceivers are an accurate method of determining distance in a moving vehicle.

[0013] According to various aspects, the method further comprises repeatedly updating the determined effective rolling radius. Thus, the determined effective rolling radius remains up to date despite changes in, for example, operating conditions and tire states.

[0014] According to a further aspect, the method further comprises repeatedly updating the predetermined relationship between the loaded tire radius and the effective rolling radius of the tire. Thus, the predetermined relationship remains up to date despite changes in, for example, operating conditions and tire status.

[0015] According to various aspects, the method further comprises determining a reliability factor of the measured distance. The method may further comprise updating the determined effective scrolling radius when the reliability factor exceeds a predefined reliability threshold, thereby indicating that the measured distance is determined to be reliable. It is beneficial if the effective scrolling radius is updated only when the measured distance is reliable and it can be assumed that the measured distance is correct.

[0016] According to various aspects, the method further comprises determining a wheel slip and / or slip angle of a wheel of the heavy vehicle by obtaining information about a rotational speed of the wheel, and determining the wheel slip and / or slip angle of the wheel based on the rotational speed of the wheel and the effective rolling radius. Being able to determine wheel slip and / or slip angle in an accurate manner is advantageous because this information can be used to control the movement of the heavy vehicle, for example using a simulated tire model.

[0017] According to various aspects, the method further comprises detecting a tire blowout event by comparing the measured distance to an expected distance range and detecting a tire blowout condition when the measured distance is outside the expected distance range for a predefined period of time. Being able to detect a tire blowout event as early as possible is beneficial because it is a cause of an accident due to loss of vehicle control.

[0018] According to various aspects, the method further comprises determining ground clearance based on the measured distance and a predetermined relationship between the measured distance and the ground clearance of the heavy vehicle.Being able to accurately determine ground clearance is beneficial because it is an important factor in determining a variety of characteristics of a vehicle, particularly in the presence of an automatic leveling suspension system.

[0019] According to one aspect, there is provided an apparatus for determining at least an effective rolling radius of a tire mounted on a heavy vehicle. The apparatus comprises a control unit configured to determine a measured distance between a predefined point of the vehicle and a ground plane supporting the vehicle; determine a loaded tire radius of a tire of the vehicle based on the measured distance; obtain a predetermined relationship between the loaded tire radius and an effective rolling radius of the tire; and determine the effective rolling radius of the tire based on the determined loaded tire radius and the predetermined relationship between the loaded tire radius and an effective rolling radius of the tire.

[0020] In some aspects, the apparatus further comprises at least one radar transceiver. The at least one radar transceiver is arranged to transmit and receive radar signals directed at a known angle between a vertical plane and a horizontal plane of the heavy vehicle. The control unit is configured to determine the measured distance by adjusting the distance measured by the radar signal by compensating for the known angle.

[0021] In some aspects, the control unit is configured to obtain the vehicle speed from the at least one radar transceiver.

[0022] In some aspects, the vehicle speed includes information related to a longitudinal speed of the vehicle and / or a lateral speed of the vehicle.

[0023] In some aspects, the control unit is further configured to determine a prediction and / or estimate of road surface roughness and / or road surface classification based at least on the measured distance and the vehicle speed.

[0024] In some aspects, the at least one radar transceiver is mounted at an angle between a vertical plane and a horizontal plane of the heavy vehicle.

[0025] A control unit, a vehicle, a computer program, a computer readable medium and a computer program product associated with the advantages discussed above are also disclosed herein.

[0026] Generally, unless otherwise clearly defined herein, all terms used in the claims should be interpreted according to their ordinary meanings in the art. All references to "a / an / the element, device, part, means, step, etc." will be interpreted as referring to at least one instance of the element, device, part, means, step, etc., unless otherwise clearly stated. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless clearly stated. Other features and advantages of the present invention will become apparent when studying the attached claims and the following description. The technician will appreciate that, without departing from the scope of the present invention, different features of the present invention may be combined to form embodiments other than the embodiments described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and additional objects, features and advantages will be better understood through the following illustrative and non-limiting detailed description of exemplary embodiments, in which:

[0028] Figure 1 A vehicle for cargo transportation is shown;

[0029] FIG. 2A to FIG. 2B The tires of the vehicle are shown;

[0030] Figure 3 is a graph showing exemplary tire forces as a function of wheel slip;

[0031] FIG. 4A to FIG. 4B An example of an arrangement in a heavy vehicle is shown;

[0032] FIG. 5A to FIG. 5D is a flow chart illustrating a method;

[0033] FIG. 6A to FIG. 6B A radar system is shown;

[0034] Figure 7 An exemplary heavy vehicle is shown;

[0035] FIG. 8A to FIG. 8B The detection principle based on Doppler difference is shown;

[0036] Fig. 9 A ground radar system is schematically shown;

[0037] FIG. 10A to FIG. 10B shows a range-Doppler plot of an exemplary received radar signal;

[0038] Fig.11A sensor unit and / or a control unit are schematically shown; and

[0039] Fig.12 An exemplary computer program product is schematically illustrated. DETAILED DESCRIPTION

[0040] The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. However, the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for the sake of thoroughness and completeness. Throughout this specification, like reference numerals refer to like elements.

[0041] Figure 1 A heavy vehicle 100 is shown. This particular example includes a tractor unit 110 arranged to tow a trailer unit 120. The tractor 110 includes a vehicle control unit (VCU) 130 arranged to control various functions of the vehicle 100. For example, the VCU may be arranged to perform vehicle motion management (VMM) functions, including controlling wheel slip, vehicle unit stability, etc. The trailer unit 120 optionally also includes a VCU 140, which controls one or more functions on the trailer 120. One VCU or multiple VCUs may be communicatively coupled to a remote server 150, for example via a wireless link. The remote server may be arranged to perform various configurations of the ECU and provide various forms of data to the ECU 130, such as providing data about the brand and type of tires installed on the vehicle 100, as will be discussed in more detail below.

[0042] Of course, the vehicle combination 100 may also include additional vehicle units, such as one or more tractor units and more than one trailer unit.

[0043] The vehicle 100 is supported by wheels 102, each of which includes a tire. The tractor unit 110 has front wheels 102a that are normally steered and rear wheels 102b, wherein at least one pair of rear wheels are driven wheels. Typically, the rear wheels of the tractor 110 may be mounted on a tag axle or a push axle. A tag axle refers to where the rearmost drive axle is unpowered, also known as a free rolling axle or a fixed axle. A push axle refers to where the frontmost drive axle is not powered. The trailer unit 120 is supported on the trailer wheels 102c. Trailers with driven wheels and even steered axles are also possible.

[0044] One of the rear axles and / or one of the axles on the trailer 120 may be a liftable axle. A lift axle (also called a telescopic axle) is an axle that can be lifted so that its tires do not contact the road surface. This improves fuel economy and reduces maintenance and tire wear. It may also reduce or increase the dynamic stability characteristics of the vehicle, and it may increase or reduce road wear, depending on the vehicle load, which axles are lifted, and the driving conditions in which the axles are lifted. One or more of the wheels may also be mounted with an active suspension that may be controlled by the VCU 130, 140, for example, to adjust the normal force of one or more tires.

[0045] Figure 2A Forces acting on tires 230 are shown. The tires 230 on wheels 102a-c of a vehicle, such as vehicle 100, play a significant role in determining the behavior and capabilities of vehicle 100. A well-designed set of tires will provide good traction and fuel economy, while a poorly designed set of tires or excessively worn tires may reduce traction and fuel economy, and may even cause the vehicle combination to become unstable, which is of course undesirable.

[0046] refer to Figure 2A , the tire 230 is subjected to a longitudinal force F x , lateral force F y and the normal force F z . Normal force F z It is the key to determine some important vehicle properties. For example, the normal force largely determines the longitudinal tire force F that can be achieved by the wheel. x , because usually, ,in is the friction coefficient associated with the road friction conditions. The maximum available lateral force for a given lateral slip can be described by the so-called magic formula as described in "Tyre and vehicle dynamics" by Hans Pacejka, Elsevier Ltd. 2012, ISBN 978-0-08-097016-5, where wheel slip and tire forces are also discussed in more detail.

[0047] Many VMM systems rely on real-time knowledge of the vehicle's motion relative to the road surface. In prior art systems, this information is primarily estimated based on wheel speed information and measurements received from accelerometers and gyroscopes. These methods can only provide accurate estimates if the rolling circumference of the tire is known and the level of wheel slip between the tire and the road can be accurately predicted for at least some of the wheels. The tire radius over which the wheel torque acts (i.e., the loaded tire radius) is also important when mapping global forces and actuator torque requests in vehicle motion management control.

[0048] The present disclosure relates to an apparatus and method for determining tire parameters, and more particularly to an apparatus and method for determining the effective rolling radius of a tire 230 mounted on a vehicle, such as a heavy vehicle 100. This is achieved by using a measured distance and a predetermined relationship between the loaded tire radius of the tire and the effective rolling radius. The apparatus and method may also be used to determine other parameters related to the tire, road conditions, and the vehicle 100 itself, such as, for example, wheel slip, slip angle, tire blowout events, ground clearance, road surface roughness, and road surface classification. By means of the present method and apparatus, a real-time estimate of the effective rolling radius may be obtained, and therefore other parameters that depend on an accurate estimate of the effective rolling radius may also be estimated in real-time.

[0049] In reference to Figures 4 to Fig.11 Before describing the device and method in detail, reference will be made to FIGS. Figure 3 Some important properties and characteristic parameters of the tire are discussed. These tire parameters are optionally included in the tire model as tire parameters based on which the VCU 130, 140 can determine other capabilities and characteristics of the tire, or simply as tire characteristics that can be used more or less directly by the VCU 130, 140 to optimize various control decisions.

[0050] Figure 2B The diagram in the figure shows the speed under the applied load. Moving tire 230. Radius is the radius of the tire in an unloaded, stationary state, radius R f is the free undeformed radius that may vary around the circumference of the tire due to tire non-uniformity, and is the effective rolling radius. Load tire radius Defined as the vertical distance between the center of the wheel and the horizontal surface. A freely rolling tire rotates about a certain point near the contact patch. For a rigid wheel on a flat horizontal surface, this point coincides with the single point of contact between the tire and the road. Therefore, the forward speed Equal to the angular velocity ω x Multiply by (full load = empty load) radius. The load radius of the tire of the vehicle 100 when it is unloaded and stationary Of course, it is equal to the free undeformed radius Rf when no wheel load is applied. Symbol C e The effective rolling circle of the tire is defined and used to estimate the free undeformed radius R f , in other words, the loaded tire radius It is the distance from the center of the wheel down to the flat part that contacts the ground, such as Figure 2B The effective wheel radius can be defined as the rolling distance normalized by 2*pi (assuming there is no slip).

[0051] Tires that rotate at higher speeds tend to develop a larger diameter, i.e., a larger rolling radius, because centrifugal forces force the tread rubber away from the axis of rotation. This effect is often referred to as centrifugal growth. As tire diameter increases, tire width decreases. Excessive centrifugal growth can significantly affect tire behavior.

[0052] Rolling resistance is the resistance to rolling caused by deformation of the tire in contact with the road surface. As the tire rolls, the tread enters the contact zone and deforms flatly to conform to the road. The energy required to deform depends on the inflation pressure, rotational speed, and many physical properties of the tire structure, such as spring force and stiffness. In trucks, where rolling resistance accounts for a high percentage of fuel consumption, tire manufacturers generally seek tire structures with lower rolling resistance to improve fuel economy.

[0053] The trail of a tire is the trail-like effect that occurs when an elastic tire rolls on a hard surface and is subjected to a lateral load (such as in a turn). The trail parameter of a tire describes the distance behind the geometric center of the tire's contact patch that the point of action of the resultant force of the tire's sideslip is.

[0054] Slip angle or sideslip angle (denoted as ) is the angle between the actual direction of travel of the rolling wheel and the direction it is pointing (i.e., the angle of the vector sum of the wheel translational velocities).

[0055] The slack length of a tire is a property of an inflated tire that describes the delay between the introduction of slip angle and the time when the cornering force reaches a steady-state value. Typically, the slack length is defined as the rolling distance required for the tire to reach 63% of the steady-state lateral force, but other definitions are possible.

[0056] Vertical stiffness or spring rate is the ratio of the vertical force to the vertical deflection of the tire, and it contributes to the overall suspension performance of the vehicle. Generally speaking, spring rate increases with inflation pressure. The vertical stiffness of a tire as a function of tire pressure is known from the design of the tire.

[0057] The contact patch or footprint of a tire is the area of ​​the tread that contacts the road surface. This area transfers forces between the tire and the road via friction. The aspect ratio of the contact patch affects steering and cornering behavior. The tire tread and sidewall elements undergo deformation and recovery as they enter and leave the contact patch. Since rubber is elastomeric, it deforms during this cycle. As the rubber deforms and recovers, it applies cyclical forces to the vehicle. These variations are collectively referred to as tire uniformity. Tire uniformity is characterized by radial force variation (RFV), lateral force variation (LFV), and tangential force variation. Force variation machines are used at the end of the manufacturing process to measure radial force variation and lateral force variation. Tires that exceed specified limits for RFV and LFV are rejected. Tire uniformity machines are used at the tire plant at the end of the manufacturing process to measure geometric parameters (including radial runout, lateral runout, and sidewall ridge) as a quality check.

[0058] The cornering force or lateral force of a tire is the lateral (ie, parallel to the road surface) force generated by a vehicle's tire during cornering.

[0059] Ride comfort is concerned with the overall experience a driver or passenger has while riding in a vehicle. Ride comfort depends on the behavior of the vehicle, which in turn depends on the properties of the tires.

[0060] Self-aligning torque (SAT) is the moment generated by a tire as it rolls which tends to steer the tire, ie, to rotate it about its vertical axis.

[0061] A tire model can be used to describe the properties of a particular tire, such as those described above and others. For example, a tire model can be used to define the relationship between the longitudinal tire force Fx for a given wheel and the equivalent longitudinal wheel slip for that wheel. Longitudinal Wheel Slip This is related to the difference between wheel rotation speed and ground speed and is discussed in more detail below. is the rotational speed of the wheel given in units such as revolutions per minute (rpm) or angular velocity in terms of radians per second (rad / sec) or degrees per second (deg / sec). Hans Pacejka, "Tyre and vehicle dynamics", Elsevier Ltd. 2012, ISBN 978-0-08-097016-5 discusses wheel characteristics from the perspective of wheel forces generated in the longitudinal direction (rolling direction) and / or in the transverse direction (orthogonal to the longitudinal direction) as a function of wheel slip. See, for example, Chapter 7, which discusses the relationship between wheel slip and longitudinal force.

[0062] According to SAE J670 (SAE Vehicle Dynamics Standards Committee, January 24, 2008), longitudinal wheel slip Can be defined as in is the effective wheel radius in meters, is the angular velocity of the wheel, and is the longitudinal velocity of the wheel (in the wheel's coordinate system). Therefore, is between -1 and 1 and quantifies the degree to which the wheel is slipping relative to the road surface. Wheel slip is essentially the speed difference between the measured wheel and the vehicle. Therefore, the techniques disclosed herein can be adapted for use with any type of wheel slip definition. It should also be understood that in the coordinate system of the wheel, given the speed of the wheel on the road, the wheel slip value is equivalent to the wheel speed value.

[0063] The lateral slip of a tire is the angle between the direction the tire is moving and the direction the tire is pointing. Lateral slip can occur, for example, when cornering and is caused by deformation of the tire structure and tread. Despite the name, actual slip is not required for small slip angles. Lateral wheel slip is usually defined as in is the longitudinal velocity component of the wheel motion, and is the lateral velocity component of the wheel motion. Lateral tire slip is discussed in detail by Hans Pacejka in "Tyre and vehicle dynamics", Elsevier Ltd., 2012, ISBN 978-0-08-097016-5.

[0064] Lateral wheel slip It can also be optionally defined as in is with the longitudinal speed The lateral velocity of the wheel (in the wheel's coordinate system) measured in a direction orthogonal to the direction of

[0065] In order for a wheel (or tire) to generate a wheel force, slip must occur. At small slip values, the relationship between slip and generated force is approximately linear, with the proportionality constant usually denoted as the tire's slip stiffness.

[0066] Figure 3 The achievable tire force F is shown x 、F y Example graph 200 of longitudinal tire force F as a function of wheel slip. xA portion 210 showing an almost linear increase at small wheel slip is shown, followed by a portion 220 with a more nonlinear behavior at larger wheel slip. Even at relatively small longitudinal wheel slip, the achievable lateral tire force F y It is desirable to maintain vehicle operation in the linear region 210, where the longitudinal forces available in response to an applied braking command are more predictable and where sufficient lateral tire forces can be generated if necessary. To ensure operation in this region, a wheel slip limit of approximately, for example, 0.1 may be applied to a given wheel. For larger wheel slips, for example exceeding 0.1, a more non-linear region 220 results.

[0067] For both longitudinal and lateral tire forces, the wheel forces can be described in the linear region by the stiffness, i.e., in is a parameter indicating tire wear. is the tire slip angle, and and is a function of the stiffness. Tire stiffness and Usually with wear and tear and normal force The above two functions both represent tire models that depend on tire parameters and vehicle state properties. Given a tire model, such as the function and / or function And tire parameters With the relevant input data, the VCU can obtain an accurate relationship between the generated wheel force and wheel slip. This relationship varies according to the tire parameters, i.e., it is a relationship that changes over time due to tire wear and tire normal force. Dynamic relationships that update when they change.

[0068] Such a tire model can be determined by actual experiments, analytical derivation, computer simulation, or a combination of the above methods. In practice, the tire model can be represented by a lookup table (LUT) indexed by tire parameters, or represented as a set of coefficients describing a polynomial, etc., wherein the set of coefficients is selected based on the tire parameters, and wherein the polynomial describes the relationship between the tire behavior and the vehicle state.

[0069] Alternatively or in addition, other tire models of interest may model tire wear rate as a function of, for example, vehicle speed and normal load, and / or model tire rolling resistance for a given vehicle state, which rolling resistance in turn depends on specific tire parameters of the tire currently mounted on a given wheel. However, as previously mentioned, the methods disclosed herein may be used independently without an existing tire model.

[0070] Figure 4A Figure B shows an aspect of an apparatus 300. The apparatus 300 comprises a control unit 130, 140, 150. The control unit may form part of a vehicle control unit (VCU) 130, 140 or a remote server 150, as previously described. As will be described in more detail, the control unit may also form part of a sensor apparatus.

[0071] The device 300 may further comprise a sensor device comprising at least one distance sensor 110 configured to determine a measured distance between a predetermined point P1 of the vehicle 100 and a ground plane 101 supporting the vehicle 100. The predetermined point P1 of the vehicle 100 is preferably a point from which the at least one distance sensor 110 makes a measurement.

[0072] The distance sensor 110 can be mounted, for example, on an axle of the vehicle 100 or elsewhere on the chassis of the vehicle 100. According to some aspects, Figure 4A As shown, the distance sensor 110 is arranged parallel to the horizontal plane of the vehicle 100. In this definition, the horizontal plane of the vehicle defines its length and width. The vertical axis is arranged perpendicular to the horizontal plane and defines the height of the vehicle. When the vehicle 100 is located on a flat surface, the vertical axis extends upward from the ground surface 101. In other words, the distance sensor 110 in this embodiment is arranged at an angle of 0 degrees relative to the ground surface 101 when the vehicle 100 is located on a flat surface.

[0073] exist Figure 4A In the embodiment, the distance signal 114 is transmitted toward the ground 101 at a known angle A1. The angle A1 is known and preferably non-zero. The distance signal 114 is used to determine at least the distance d1 or the distance d2. In another aspect, the distance signal 114 is also used to determine at least one velocity component of the vehicle. This will refer to FIG. 5A to FIG. 5C Describe in more detail.

[0074] The distance sensor 110 is preferably arranged in a certain direction so that the distance signal 114 points to the wheel track to which the wheels of the heavy vehicle 100 are about to move.

[0075] In some aspects, such as Figure 4BAs shown, the distance sensor 110 is arranged at an angle between a horizontal plane and the vertical axis of the vehicle 100. The angle of the distance sensor 110 will provide a distance signal 114 with a known angle A1 toward the ground surface 101. The angle A1 is a known angle and is different from zero degrees. Therefore, in other words, the distance sensor 110 is arranged at a certain angle relative to the ground surface 101.

[0076] According to some aspects, at least one distance sensor 110 is any one of an ultrasonic sensor, a radar sensor, an infrared distance sensor, or an LED time-of-flight sensor. All of these sensors have their own disadvantages and benefits, and which type to use depends on the heavy vehicle and its operating conditions.

[0077] Refer to Figure 6 to Fig. 9 , an implementation in which the distance sensor 110 is a radar transceiver 210 will be further described.

[0078] FIG. 5A to FIG. 5C The flowchart in shows a method for determining the effective rolling radius Re of a tire and a method for determining parameters such as wheel slip, slip angle, ground clearance, road surface roughness and road surface classification. The method may also include detecting a tire burst event. The method may be performed by a VCU 130, 140 in the vehicle 100, or at least partially by a remote server 150. Such a VCU may be implemented in a central processing unit or distributed in several units.

[0079] Figure 5A A method is shown for determining at least an effective rolling radius of a tire mounted on a heavy vehicle 100. The method comprises obtaining S1 a measured distance d1 between a predetermined point P1 of the vehicle 100 and a ground plane 101 supporting the vehicle 100. The distance d1 is measured by at least one distance sensor 110. The predetermined point P1 of the vehicle 100 is preferably a point from which the at least one distance sensor 110 makes a measurement.

[0080] According to some aspects, at least one distance sensor 110 is any one of an ultrasonic sensor, a radar sensor, an infrared distance sensor, or an LED time-of-flight sensor. All of these sensors have their own disadvantages and benefits, and which type to use depends on the heavy vehicle and its operating conditions.

[0081] The method may further comprise receiving, preferably by means of a control unit, a distance signal 114 from a distance sensor 110, the distance signal being directed to an angle A1 between a vertical plane and a horizontal plane of the heavy vehicle 100. The angle A1 is a known angle and is different from zero degrees. The method may further comprise adjusting the distance measured by the distance signal 114 by compensating for the known angle A1, thereby determining the measured distance. The vertical distance to the ground surface 101 may be determined using the angle A1. The measured distance transmitted to the control unit may be the actual measured distance, or an adjusted distance taking into account the angle and the radius of the loaded tire.

[0082] According to some aspects, the measured distance d1 is determined according to the radar transceiver 110 described herein. Then, the method may also include receiving a radar signal 115 (as shown in FIG8 ) directed at an angle A1 between a vertical plane and a horizontal plane of the heavy vehicle 100. Angle A1 is a known angle and is different from zero degrees. The method also includes determining the measured distance d1 by adjusting the distance measured by the radar signal 115 by compensating for the known angle A1.

[0083] The method further comprises determining S2 a loaded tire radius R of a tire of the vehicle 100 based at least on the measured distances d1, d2 e . The loaded tire radius is determined at least in part by knowing the distance between the tire and the sensor. In addition, it is helpful to know the relative geometry between the sensor and the tire. In one aspect, the distance measurement is a vector with the distance sensor as the origin. A linear transformation is performed from the measured distance vector to the distance vector from the center of the wheel to the ground. Therefore, the angle of the sensor (A1 in Figure 4) and the vertical translation of the sensor relative to the wheel axle are used to determine the loaded tire radius R of the tire. e The data may be obtained from a database stored in memory 565. In some aspects, the linear transformation is determined by a calibration process. This may be accomplished by knowing the true wheel radius and / or the distance between the axle and the ground, and comparing that data to the measured data.

[0084] In some aspects, the loaded tire radius is determined based on the measured distance d1 and any operating parameters. More specifically, the loaded tire radius can be determined based on the measured distance d1 and suspension parameters. This is particularly beneficial when there is a non-rigid element between the sensor and the axle.

[0085] In some aspects, the loaded tire radius is determined based on the measured distance d1 and a load measurement obtained from the suspension system. The vertical stiffness and the measured load can be used to determine the difference between the unloaded and loaded tire radii. More specifically, the vertical stiffness multiplied by the measured load can yield the difference between the unloaded and loaded tire radii.

[0086] In some cases, there is an unknown vertical translation between the axle of the vehicle and the sensor location. This may occur if the vehicle 100 is provided with a bellows. The vertical translation between the axle and the sensor location can be estimated by measuring the bellows pressure. Thus, in some aspects, the loaded tire radius is determined based on the measured distance and the bellows pressure. In yet other aspects, the loaded tire radius is determined based on the measured distance and data received from a linear encoder that provides information about how much the leaf spring is compressed, thereby providing information about the vertical translation between the axle and the sensor location.

[0087] The method also includes obtaining a predetermined relationship between the loaded tire radius and the effective rolling radius of the S3 tire. The predetermined relationship can be part of the tire model, or as a separate relationship.

[0088] According to some aspects, the predetermined relationship is obtained based on tire design data S3a of the tire. The tire design data S3a can be obtained from a memory 565 associated with the tire design. The data S3a associated with the tire design optionally includes any one of the tire nominal size, tire structural characteristics, tire chemical composition, and tire history. The tire design data may include configuration data related to the tire brand and / or model, the chemical composition of the tire, the tire nominal size, or other structural and mechanical properties and characteristics of the tire. Optionally, the data associated with the tire design also includes a tire history indicating whether the tire has been subjected to any treatment or event that may have changed the behavior of the tire. For example, the tire may have been subjected to tread retreading and / or may have been repaired in a manner that may affect its behavioral characteristics.

[0089] According to some aspects, the predetermined relationship is obtained based on input data from one or more sensors, which are arranged to measure one or more operating parameters S3b of the tire. One or more sensors can be arranged to be connected to the actual tire and / or sensors arranged on the vehicle 100. These optional sensors are arranged to measure one or more operating parameters of the tire, wherein the one or more operating parameters may include any of the following: vehicle speed, wheel rotation speed, tire pressure, tire temperature, tire acceleration, tire strain, tire GPS position, weather, ambient temperature, rain classification data, normal load, slip angle, steering angle and positive / negative torque applied to the tire. The vehicle speed can be obtained by a speed sensor (such as a GPS sensor and / or a radar sensor).

[0090] According to some aspects, the predetermined relationship is obtained according to one or more preconfigured or estimated tire parameters S3c. The tire parameters may be preconfigured. However, if the tire parameters are estimated or otherwise determined based on the tire data obtained from the memory 565 or based on the tire data obtained from one or more sensors 510, additional advantages may be obtained. Some of the parameters may be determined directly. For example, the nominal tire air pressure may be given directly from a pressure sensor arranged to measure tire pressure. Other parameters of the tire may be estimated based on tire data obtained from one or more sensors. For example, tire wear may be estimated by integrating the estimated tire wear rate or simply based on tire age. The tire parameters S3c may include any of the following: tire wear, tire longitudinal stiffness, tire lateral stiffness, tire rolling resistance, tire peak friction, tire contact patch properties, tire balance properties, and wheel alignment properties. The tire parameters may optionally be estimated or regularly updated by a tire parameter estimation software (TYPRESSW) module.

[0091] According to some aspects, the predetermined relationship between the load tire radius and the effective rolling radius of the tire is obtained by parameterization. In one embodiment, a parameter space of the vehicle state is established. This space is used to parameterize the mapping from the load tire radius to the effective tire radius. This is preferably completed using pre-configured or estimated tire parameters S3c, operating parameters S3ba and / or tire design data S3a. The mapping can be retrieved from a memory that can be configured at the factory site of the vehicle 100. In some embodiments, the mapping is updated during the maintenance of the vehicle 100. In some aspects, the mapping can be updated in real time. In one embodiment, the mapping is updated by implementing an effective rolling radius estimator that estimates the effective rolling radius. In one embodiment, the mapping is updated by measuring the distance traveled by the vehicle and then comparing the distance with the wheel revolutions. The distance can be obtained from a sensor (such as a GPS). The wheel revolutions can be obtained from a sensor (such as a wheel speed sensor).

[0092] The method further includes determining an effective rolling radius of the S4 tire based on the determined loaded tire radius and a predetermined relationship between the loaded tire radius and the effective rolling radius of the tire.

[0093] According to yet other aspects, the method further comprises determining S8 a tire blowout event. A blowout event (also referred to as a tire blowout) refers to a rapid, explosive drop in the air pressure of a tire. However, a blowout event may also be an impact damage event in which the inflation pressure is not affected. Therefore, the term blowout event should be understood to also cover impact damage events.

[0094] Preferably, a tire blowout event is determined S8 by obtaining the measured distance d1 and comparing the measured distance with an expected difference range. The method also includes detecting a tire blowout. When the measured distance is outside the expected difference range, a tire blowout is preferably detected. When the measured distance is outside the expected difference range for a predetermined time, a tire blowout is preferably detected. The predetermined time length is preferably set to a time that allows at least two distance readings. This increases the reliability of determining whether the tire has blown out. The predetermined time length can be, for example, milliseconds or seconds, depending on the sensor providing the distance measurement.

[0095] In one aspect, the expected difference range is in the form of a lookup table that defines the highest and lowest allowed distance differences. In an alternative aspect, the expected difference range is defined by comparing the measured distance d1 to at least one predetermined threshold. The range can be defined by a lower threshold and an upper threshold. If the measured distance d1 is below the lower threshold or above the upper threshold, the measured distance is outside the expected difference range.

[0096] In some aspects, if a tire blowout event is detected, a feedback event is triggered. The feedback event may be an alarm, such as a sound, flashing lights, or the like for signaling a blowout event to the driver. Alternatively or additionally, the feedback event is transmitted to the vehicle control unit and vehicle motion management.

[0097] In some aspects, the method also includes determining the ground clearance of the S9 vehicle 100. Ground clearance or ride height is the distance between the bottom of the tires and the lowest point of the vehicle. In other words, it is the shortest distance between a flat, horizontal surface and the lowest part of the vehicle other than those parts designed to contact the ground.

[0098] The ground clearance is determined based on at least the measured distance d1 and a predetermined relationship between the measured distance and the ground clearance of the heavy vehicle. The predetermined relationship between the measured distance and the ground clearance of the heavy vehicle 100 may be obtained based on preconfigured data stored in a memory or based on a lookup table. The predetermined relationship between the measured distance and the ground clearance may be obtained based on a vehicle-related constant value and a loaded tire radius determined based on the measured distance d1.

[0099] In some aspects, the determined ground clearance is compared to at least one predetermined ground clearance threshold. The method may also include detecting an anomaly in the determined ground clearance. An anomaly is preferably detected when the determined ground clearance is outside an expected difference range (preferably for a predetermined time).

[0100] In one aspect, the expected difference range is in the form of a lookup table that defines the highest and lowest allowed distance differences. In an alternative aspect, the expected difference range is defined by comparing the determined ground clearance to at least one predetermined threshold. The range may be defined by a lower threshold and an upper threshold. If the determined ground clearance is below the lower threshold or above the upper threshold, the determined ground clearance is outside the expected difference range. Thus, an abnormality in the ground clearance is detected.

[0101] If an abnormality in ground clearance is detected, a feedback event may be triggered. The feedback event may be an alarm, such as a sound, flashing lights or the like for signaling an abnormality in ground clearance to the driver. Alternatively or additionally, the feedback event is transmitted to the vehicle control unit and the vehicle motion management.

[0102] In some aspects, in addition to the measured distance, ground clearance can also be determined based on data received from the suspension system. The data may be related to the steering lift of the vehicle 100. When the axle (e.g., the front axle) is turned, the geometry of the suspension will lift the vehicle body relative to the ground. All effects of the suspension are known from the design, and by measuring the steering angle, the lift effect can be estimated.

[0103] Now go to Figure 5B In some aspects, the effective rolling radius Re determined in S5 is updated repeatedly. Thus, preferably, the determination of the effective rolling radius is dynamic rather than static. Thus, the effective rolling radius will be updated regularly to take into account new measurements of the distance d1 and / or updates to the predetermined relationship between the loaded tire radius of the tire and the effective rolling radius.

[0104] The updating of the determined effective rolling radius may be based on a predetermined time scheme, such as updating the determined effective rolling radius after a certain time. The time scheme may be seconds, minutes or hours, depending on the circumstances. The updating of the determined effective rolling radius Re may be additionally or alternatively based on the reading of the distance sensor 110. For example, each time a change in the measured distance d1 is detected, the determined effective rolling radius is updated. In yet another example, each time a change in the measured distance d1 is detected that exceeds a predefined threshold, the effective rolling radius is updated. Furthermore, the updating of the determined effective rolling radius may be additionally or alternatively based on a change or update in a predetermined relationship between the loaded tire radius and the effective rolling radius of the tire. For example, if a tire parameter (e.g., an operating parameter) that affects the relationship changes, the determined effective rolling radius is updated.

[0105] In some aspects, the predetermined relationship between the loaded tire radius and the effective rolling radius of the S6 tire is repeatedly updated. Thus, preferably, the predetermined relationship is dynamic rather than static. Thus, the predetermined relationship will be updated regularly to account for changes. Thus, if tire parameters, tire design data, or operating parameters change over time, then the relationship will also change to maintain an accurate mapping between the measured distance d1 and the effective rolling radius.

[0106] The predetermined relationship between the loaded tire radius and the effective rolling radius of the tire may be updated using input data from one or more sensors. For example, the relationship may be updated by a combination of GPS data and input data from a wheel speed sensor that measures the number of wheel revolutions.

[0107] This means that as the tire evolves during its life cycle, from new to almost worn out and in need of replacement, the predetermined relationship between the loaded tire radius and the effective rolling radius and the determined effective rolling radius will remain up to date. The predetermined relationship will therefore be more accurate than a fixed configuration's predetermined relationship. Furthermore, the predetermined relationship will react to misconfigurations and eliminate any discrepancies between the pre-configured data and the actual behavior of the tire. This will enable a more accurate determination of the effective rolling radius.

[0108] In some aspects, the method includes determining a reliability factor S5a for the measured distance. The reliability factor indicates whether the measured distance is determined to be reliable. As will be described, it is beneficial to update the effective scrolling radius only when the measured distance is reliable. In other words, if the measured distance is considered unreliable, it is preferred not to update the effective scrolling radius based on the measurement reading. Therefore, the method also includes updating the determined effective scrolling radius when the reliability factor exceeds a predefined reliability threshold. In this case, the reliability factor indicates that the measured distance is determined to be reliable. This step can be performed for a predetermined time.

[0109] The reliability factor may be obtained based on previous measurement readings, preferably for a given time interval. Thus, if the measured distance d1 changes drastically, this may indicate that the measurement is unreliable.

[0110] In different situations, the measured distance d1 may be considered unreliable. Some non-limiting examples are situations where the road surface is uneven, there are large puddles on the road, there is ice and snow on the road, strong winds, there is an oil leak on the road, the vehicle vibrates strongly, and / or the sensor sends a false signal (e.g., a bellows pressure sensor sends a false signal). The road surface may be uneven for many reasons, such as due to road erosion, potholes, gravel roads, dirt roads, and make it difficult to measure the accurate distance d1.

[0111] According to some aspects, the method further comprises determining the slip of the S7 wheel and / or slip angle As mentioned above, the slip angle Side slip angle is the angle between the actual direction of travel of the rolling wheel and the direction it is pointing, and the wheel slip It can be regarded as the speed difference measured between the wheel and the vehicle. The determination is preferably made by obtaining S7a and the rotation speed ω of the wheel of the heavy vehicle 100 x The method also includes determining the effective rolling radius Re based on the rotation speed ω of the wheel. x and effective rolling radius R e Determine the wheel slip of the S7b wheel and / or slip angle .

[0112] FIG. 5C to FIG. 5D A further method is shown in which additional input data, such as, for example, vehicle speed, is used to determine properties associated with vehicle 100. In this embodiment, the distance sensor is a radar transceiver 220 which is also configured to determine vehicle speed.

[0113] In one aspect, a single radar transceiver 220 is configured to determine a two-dimensional velocity vector. In this case, in addition to method steps S1-S4, the method further comprises configuring S10 the radar transceiver 220 to transmit a radar signal in a first direction and in a second direction different from the first direction. The method further comprises detecting S11 a first radar signal component and a second radar signal component of the received radar signal based on their respective angles of arrival (AoA). The first radar signal component has an AoA corresponding to the first direction, and the second radar signal component has an AoA corresponding to the second direction. The method further comprises determining S12 a two-dimensional velocity vector of the heavy vehicle 100 based on respective Doppler frequencies of the first radar signal component and the second radar signal component.

[0114] In yet another aspect, the two radar transceivers 220 are configured to determine a two-dimensional velocity vector based on inputs from the two transceivers. In this case, in addition to method steps S1-S4, the method also includes configuring the first radar transceiver 220 to transmit a radar signal in a first direction, and configuring the second radar transceiver 220 to transmit a radar signal in a second direction different from the first direction. The method also includes detecting a first radar signal component and a second radar signal component of the received radar signal based on their respective AoAs. The first radar signal component has an AoA corresponding to the first direction, and the second radar signal component has an AoA corresponding to the second direction. The method also includes determining a two-dimensional velocity vector of the heavy vehicle 100 based on respective Doppler frequencies of the first radar signal component and the second radar signal component.

[0115] In one aspect, the method further comprises determining S13 a prediction and / or estimation of the road surface roughness and / or road surface classification. This is determined based at least on the measured distance d1 and the vehicle speed. The vehicle speed may be obtained by one or more sensors 110 (preferably the radar transceiver 220 described above). The vehicle speed is preferably obtained by method steps S10-S12.

[0116] In a preferred aspect, determining a prediction and / or estimate of road surface roughness is based at least on the measured distance d1 , vehicle speed, and the distance data series.

[0117] It should be understood that the above FIG. 5A to FIG. 5D The steps discussed can be combined freely.

[0118] The following description will focus on an embodiment in which the distance sensor 110 is a radar transceiver 220. More specifically, the radar is a radar facing the ground plane 101 (also referred to as the ground surface) supporting the vehicle. In some aspects, the radar transceiver is a ground penetrating radar.

[0119] In one aspect, it is preferred to use a radar transceiver to determine the distance d1. However, another benefit of using a radar transceiver is that the same radar transceiver can also be used to determine the speed of the vehicle.

[0120] In a preferred embodiment, the radar transceiver is configured to determine the distance d1 from the ground plane, and the longitudinal and lateral speeds of the vehicle 100 relative to the ground plane or road surface 101 supporting the vehicle 100, preferably a two-dimensional velocity vector of the heavy vehicle 100 .

[0121] This type of radar system includes at least one radar transceiver arranged to transmit and receive radar signals 115 by an antenna array or feed antenna. The radar system may consist of a single transceiver for determining velocity in two dimensions, or of two separate radar transceivers for each dimension.

[0122] The radar transceiver illuminates a small portion of the road surface, e.g. FIG. 6A to FIG. 6B Various illumination patterns can be selected, but it is advantageous if the portion of the ground surface illuminated by a given radar transceiver is close to the wheels and is relatively small in size. FIG. 6A to FIG. 6B As shown in the figure, the illuminated portion of the ground plane 101 can be located directly behind 130a of the contact patch of the wheel 102, to the side 130b of the contact patch of the wheel 102, or in front of 130c of the contact patch of the wheel 102. The illuminated portion of the ground plane 130d can also be located in the center of the axle, as shown in the figure on the right. The illuminated portion of the ground plane is preferably within 1m of the contact patch of the wheel, because this allows a better understanding of how the wheel moves relative to the road surface. The illuminated portion of the ground plane is even more preferably within 0.5 meters of the contact patch of the wheel.

[0123] At least one radar transceiver is arranged to transmit radar signals over the radar bandwidth, wherein a larger bandwidth improves the range resolution in a known manner. The velocity resolution depends on the radar wavelength and the waveform repetition period in a known manner. According to some aspects, the transceiver is arranged to transmit a frequency modulated continuous wave (FMCW) radar signal over the radar bandwidth, wherein the frequency chirp cyclically sweeps the radar bandwidth. Other types of radar signal formats may also be used, such as a band-extended radar signal in which an orthogonal code is used to extend the modulated signal over a wide frequency band, or an orthogonal frequency division multiplexing (OFDM) radar signal. Given an FMCW radar signal format, the distance to the ground plane 101 (and to the reflective material under the road surface) can be determined based on a first discrete Fourier transform (DFT) or a fast Fourier transform (FFT), and the radial velocity or Doppler frequency of the illuminated portion of the ground can be determined based on a second DFT or FFT in a known manner. The results of applying the range FFT and Doppler FFT are usually represented as a range-Doppler diagram or simply referred to as an RD diagram. The range-Doppler map is a complex-valued matrix in which each column index corresponds to the backscattered energy received by a given radar antenna from a reflection at a given distance, and in which each row index corresponds to the backscattered energy received at a given radar antenna from a reflection at a given radial velocity relative to the position of the radar transceiver. A good overview of basic FMCW radar processing is given in the lecture note "Introduction to mmwave Sensing: FMCW Radars", Sandeep Rao, Texas Instruments, 2017. The Doppler frequency over a range corresponding to the distance between the radar transceiver and the ground indicates the radial velocity at which the ground is moving relative to the radar transceiver, as explained in US 2004 / 0138802.

[0124] As previously described, determining both the longitudinal velocity and the lateral velocity of the vehicle 100 may be accomplished by one radar transceiver transmitting radar signals in two directions, or by two radar transceivers each transmitting in one direction.

[0125] The following will focus on the aspect of using only one radar transceiver to determine both the distance d1 and the longitudinal and lateral speeds of the vehicle 100. In this case, the radar transceiver is configured to transmit the radar signal 115 in a first direction d4 and a second direction d3 different from the first direction. This means that the radar signal illuminates the ground plane 101 in at least two directions. This can be achieved by illuminating a larger area of ​​the road surface with a relatively wide antenna beam, or by illuminating two or more separate sections of the ground plane or road surface 101 with multiple narrower beams.

[0126] As previously referenced Figure 4BAs mentioned above, the radar transceiver 220 can be mounted to the vehicle chassis so that both the first direction and the second direction point to the ground, but in different directions. Because the radar illuminates the ground in at least two different directions, it is able to receive backscattered radar signals from two or more different directions. When the radar transceiver 220 is mounted on the chassis, it may be beneficial if a predetermined relationship between the loaded tire radius and the effective rolling radius is obtained based on data related to the suspension system (e.g., from a suspension level sensor). Alternatively, the determination of the loaded tire radius is based on the measured distance and the data received from the suspension system.

[0127] As previously referenced Figure 4B As mentioned above, the radar transceiver 220 may be mounted to a vehicle axle.

[0128] The heavy vehicle 100 may be arranged with a plurality of radar transceivers distributed over the length of the vehicle. Figure 7 In the illustration, the vehicle 100 is a heavy vehicle 100 having a towing truck configured as a towing trailer unit, wherein the vehicle 100 comprises a system 600 of radar transceivers 110 distributed on the heavy vehicle 100 .

[0129] The radar transceiver or a radar module comprising the transceiver may further comprise a processing device, the processing device being arranged to detect the first radar signal component and the second radar signal component of the received radar signal 115 based on their respective angles of arrival (AoA), wherein the first radar signal component has an AoA corresponding to a first direction and the second radar signal component has an AoA corresponding to a second direction. The processing device is arranged to determine the two-dimensional velocity vector of the heavy vehicle 100 based on the respective Doppler frequencies of the first radar signal component and the second radar signal component. Thus, in summary, the radar transceiver illuminates one or more portions of the road surface below the vehicle and receives backscattered energy from the road surface from two directions. The radial velocity of the road surface in two different directions will indicate the two-dimensional velocity of the vehicle. For example, if the first direction is the longitudinal direction of the vehicle 100 and the second direction is the lateral direction of the vehicle 100, the Doppler information of the first radar signal component and the second radar signal component will directly indicate the longitudinal velocity and the lateral velocity of the vehicle. The radar transceiver can also be mounted with the steering wheel and rotate as the wheel turns, which means that the velocity component will be determined in the wheel's coordinate system without the need for a mathematical transformation from the vehicle coordinate system to the wheel coordinate system.

[0130] If the two directions point in different directions than the longitudinal and lateral directions of the vehicle, a transformation may be required to obtain the longitudinal and lateral velocities of the vehicle. This transformation is very simple and will not be discussed in detail in this article.

[0131] If the first direction and the second direction are respectively arranged on both sides of the visual axis direction of the radar module (the visual axis direction is arranged to be aligned with the longitudinal direction of the vehicle), it is particularly advantageous when determining the lateral velocity of the vehicle. In this case, the processing device can detect the lateral velocity component of the vehicle based on the difference in the corresponding Doppler frequencies of the first radar signal component and the second radar signal component.

[0132] Fig. 8A and Figure 8B The concept is shown, where Fig. 8A is a top view of an exemplary radar system mounted to a heavy vehicle 100. Fig. 8A In , the radar system has been mounted to the vehicle 100 such that its boresight direction 405 coincides with the longitudinal direction of the vehicle 100. In this particular example, the radar transceiver comprises an antenna array. Figure 8B Exemplary signal powers of radar signals received from different directions d4 and d3 are shown. Now, if the vehicle is traveling in the boresight direction 405, i.e., if there is no lateral motion, the radial motion of the road surface will be equal in both directions. That is, the Doppler frequency of the signal component received by focusing the antenna array 410 (as shown by antenna lobe 710) will be the same as the Doppler frequency of the signal component obtained when focusing the antenna array 410 (as shown by antenna lobe 720). Any lateral speed of the vehicle will result in an imbalance in the Doppler frequencies of the two antenna lobes 710, 720, i.e., the Doppler frequency measured in the first direction d4 will be different from the Doppler frequency measured in the second direction d3. If the radar component signal power is plotted compared to the Doppler frequency, as shown Figure 8B As schematically indicated, vehicles travelling in the direction of the boresight will show radar signal components with the same or at least similar Doppler frequencies. The lateral velocity will result in a difference D in the Doppler frequencies of the first direction d4 and the second direction d3, as Figure 8B This difference in Doppler frequency indicates the lateral velocity of the vehicle relative to the ground 101.

[0133] In one aspect, Fig. 9 As shown, the distance sensor is a ground penetrating radar transceiver 320, which can be used to determine the vehicle ground speed regardless of the surface conditions (i.e., whether the road surface is smooth or scatters radar signals, and whether there is reflective material on the road surface that moves relative to the road surface). The reason is that the radar transceiver has a transmit lobe that penetrates the road surface 101 and extends beyond the road surface. Therefore, radar reflections are also generated from points below the actual road surface (such as in plane 102 located at a distance Dg below the road surface 101). Fig. 9In the example of , the transmit lobe intersects plane 102 within a distance r, while the road surface 101 is located at a distance s (less than r) from the radar transceiver 1160 along the direction of the main transmit lobe. Regardless of any moving material on the road surface 101, the reflection from this point below the surface is generally guaranteed to be stable and provides a good basis for establishing the vehicle's ground speed.

[0134] According to some aspects, plane 102 is a roadbed layer associated with relatively strong scattering.The actual distance r over which the ground velocity is determined is not that important as long as it is below surface 101 away from material that could move over surface 101 and cause errors in determining the ground velocity.

[0135] The radar transceiver is advantageously configured to have a boresight direction of the transmission lobe in the longitudinal direction of the vehicle, said boresight direction intersecting the road surface 101 at an angle A1, such as Fig. 9 . This angle may vary according to different implementations, but values ​​between 30 and 70 degrees have been found to give satisfactory results, and are preferably about 45 degrees. Note that the radar transceiver 320 will only detect relative velocity in its radial direction, and is not interested in the tangent component of the relative velocity between the radar transceiver and the detected target. Therefore, compensation must be made according to the angle a: in is the radial velocity determined from the Doppler frequency of the target point below the road surface. The radar signal processing involved in determining the relative velocity from the received radar reflections is well known and will not be discussed in more detail herein. For example, the technique described in EP1739451 A1 can be advantageously used to determine .

[0136] Radar transceiver 320 is preferably configured to have a transmit lobe azimuth width of less than ten degrees and preferably less than five degrees, i.e. a relatively narrow beam. Such a narrow beam reduces the amount of reflections received from the surroundings and from the vehicle itself, and thus simplifies detecting the Doppler frequency associated with a point below the road surface 101.

[0137] The carrier frequency of the radar transceiver discussed herein is preferably in the GHz range, such as over 30 GHz and preferably around 80 GHz. The reason this high carrier frequency is preferred is that the wavelength is small, which allows scattering even from relatively smooth surfaces and / or homogeneous materials. The small wavelength also improves the velocity resolution of the proposed technique.

[0138] Fig. 10AAn exemplary range-Doppler diagram of a received radar signal is schematically shown. As is known, a range-Doppler diagram visualizes the received radar echo based on the distance to the target and the radial velocity of the target relative to the radar transceiver (determined in a known manner from the Doppler shift of the received signal relative to the transmitted signal). The range-Doppler diagram allows the receiver to distinguish radar detections that are located at different distances from the radar transceiver and / or are moving at different radial velocities relative to the radar transceiver. In order to determine the radial movement speed of the point 1210 relative to the radar transceiver, the control unit only has to read the Doppler frequency at a specified distance r. Due to the azimuthal width and direction of the main transmit lobe, the reflection from the point 1210 will generally be stronger than other weaker reflections, at least when averaged over a short period of time.

[0139] Fig. 10A The common situation of several detections 1210, 1220, 1230 within a range close to the road surface (i.e., near a distance s) is shown. Therefore, it is difficult to know which of these detections indicates the true vehicle ground speed. However, all detections 1210 in the transmit lobe within a range near a distance r corresponding to a point below the road surface are usually free of clutter echoes. In order to derive the ground speed, the strongest detection at a certain distance r greater than the distance s is first derived. Next, the Doppler frequency associated with this detection (or equivalently the radial relative velocity D) is used to determine the vehicle's ground speed. If there is more than one Doppler frequency bin with non-negligible detection energy, i.e., there is more than one radar detection 1210, 1240 at a specified distance r, a weighted sum can be formed to estimate the radial speed. The weight can be determined based on the energy in each Doppler frequency bin. The strongest detection at the specified distance r can also be selected because the strongest detection is most likely to correspond to the desired radial speed.

[0140] The distance r at which the Doppler value is determined can advantageously be determined relative to the road surface, for example about 10 cm beyond the distance to the road surface, i.e. according to some aspects Where Δ is a positive offset value added to s to obtain r. This means that the actual distance r changes continuously to follow, for example, the movement of the vehicle along a vector normal to the road surface, but remains more or less at the same distance relative to the road surface 101. The road surface at distance s is usually visible as a strong reflection, but the Doppler content at this distance s may include more than one component due to the clutter echoes discussed above. Therefore, according to some aspects, the radar transceiver may first detect the distance s from the radar transceiver 320 to the road surface along the pointing direction of the antenna transmit lobe, and then determine the distance r to the point of interest below the road surface 101 relative to the road surface distance s, for example by adding a predetermined positive offset Δ to the detected distance s, as discussed above. According to other aspects, the radar transceiver 160 may only determine the distance Dg below the road surface 101 as the predetermined distance from the radar transceiver 320. In this case, any suitable distance r may be selected as long as it is greater than the distance s.

[0141] To further improve accuracy, the radar transceiver 320 may be configured to receive data indicative of the vehicle's height above the ground, or the height above the ground of the radar transceiver 320. This type of data may be obtained, for example, from a linear position sensor configured to be connected to the vehicle's suspension, such as a suspension system sensor. Thus, as the vehicle moves up and down along the normal to the road surface, the detected Doppler frequency may be adjusted to account for the motion, which improves the estimated ground velocity in the longitudinal direction.

[0142] Fig. 10B Another exemplary range-Doppler plot is shown. In this case, radar transceiver 320 detects the Doppler frequency associated with the target point as an average Doppler frequency associated with a series of distances corresponding to the volume below the road surface. Alternatively, radar transceiver 320 may perform a weighted combination of the strongest detections in range 1250 to determine the Doppler frequency from which the vehicle ground speed is determined, wherein the weights may be configured as a function of the detection strengths.

[0143] Fig.11 Components of a control unit 700 according to embodiments discussed herein are schematically shown in terms of a number of functional units, such as any of the VUCs 130, 140. The control unit 700 may be included in the heavy vehicle 100. The processing circuit 710 is provided using any combination of one or more of a suitable central processing unit CPU, a multiprocessor, a microcontroller, a digital signal processor DSP, etc. capable of executing software instructions stored, for example, in a computer program product in the form of a storage medium 730. The processing circuit 710 may further be provided as at least one application specific integrated circuit ASIC or a field programmable gate array FPGA.

[0144] In particular, the processing circuit 710 is configured to cause the control unit 700 to perform a set of operations or steps, such as combining FIG. 5A to FIG. 5D For example, the storage medium 730 may store the set of operations, and the processing circuit 710 may be configured to retrieve the set of operations from the storage medium 730 to cause the control unit 700 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus, the processing circuit 710 is thereby arranged to perform the method as disclosed herein.

[0145] The storage medium 730 may also include a persistent storage device, which may be, for example, any one or combination of magnetic storage, optical storage, solid-state storage, or even remotely mounted storage.

[0146] The control unit 700 may also include an interface 720 for communicating with at least one external device. Thus, the interface 720 may include one or more transmitters and receivers, including analog and digital components and a suitable number of ports for wired or wireless communication.

[0147] Processing circuit 710 controls the general operation of control unit 700, for example, by sending data and control signals to interface 720 and storage medium 730, by receiving data and reports from interface 720, and by retrieving data and instructions from storage medium 730. Other components of the control node and related functionality are omitted so as not to obscure the concepts presented herein.

[0148] Fig.12 A computer readable medium 810 is shown carrying a computer program comprising a program product for executing a program when the program product is run on a computer. FIG. 5A to FIG. 5D The computer readable medium and the code means may together form a computer program product 800.

Claims

1. A method for determining at least the effective rolling radius (R) of a tire (230) mounted on a heavy vehicle (100) e ), the method comprising: Determining (S1) a measured distance between a predefined point (P1) of the vehicle (100) and a ground plane (101) supporting the vehicle (100); determining (S2) a loaded tire radius of a tire of the vehicle (100) based at least on the measured distance; obtaining (S3) a predetermined relationship between a loaded tire radius and an effective rolling radius of the tire; and The effective rolling radius (R ) of the tire is determined ( S4 ) based on the determined loaded tire radius and the predetermined relationship between the loaded tire radius and the effective rolling radius of the tire. e ).

2. The computer-implemented method of claim 1, wherein the predetermined relationship is obtained based on tire design data (S3a) of the tire obtained from a memory (565) associated with the tire design.

3. The computer-implemented method according to claim 2, wherein the data (S3a) related to tire design includes any of the following: tire nominal size, tire structural characteristics, tire chemical composition, tire history.

4. A computer-implemented method according to any one of the preceding claims, wherein the predetermined relationship is obtained based on input data from one or more sensors (510), the one or more sensors being arranged to measure one or more operating parameters (S3b) of the tire.

5. The computer-implemented method of claim 4, wherein the one or more operating parameters (S3b) include any of the following: vehicle speed, wheel rotation speed, tire pressure, tire temperature, tire acceleration, tire strain, tire GPS position, weather, ambient temperature, rain classification data, normal load, slip angle , steering angle, wheel load measurements, axle load measurements, applied torque and suspension parameters.

6. A computer-implemented method according to any of the preceding claims, wherein the predetermined relationship is obtained based on one or more estimated tire parameters (S3c), the one or more estimated tire parameters comprising any of the following: tire wear, tire longitudinal stiffness, tire lateral stiffness, tire rolling resistance, tire peak friction, tire contact patch properties, tire balance properties and wheel alignment properties.

7. The computer-implemented method according to any one of the preceding claims, wherein the measured distance (d1) is determined by: receiving (S1a) a radar signal (115) from at least one radar transceiver (220), the radar signal being directed at a known angle (A1) between a vertical plane and a horizontal plane of the heavy vehicle (100), The measured distance (d1) is determined (S1b) by adjusting the distance (s) measured by the radar signal (115) by compensating for the known angle (A1).

8. The computer-implemented method according to any of the preceding claims, further comprising repeatedly updating (S5, S6) the determined effective rolling radius and / or repeatedly updating the predetermined relationship between the loaded tire radius and the effective rolling radius of the tire.

9. The computer-implemented method of any one of claims 1 to 7, further comprising: determining a reliability factor of the measured distance (S5a); as well as When the reliability factor exceeds a predefined reliability threshold, thereby indicating that the measured distance is determined to be reliable, the determined effective rolling radius is updated (S5).

10. The method according to any one of the preceding claims, further comprising determining (S7) the slip (λ) and / or the slip angle ( ): Obtain (S7a) the rotation speed (ω) of the wheel of the heavy vehicle (100) x ) Based on the rotation speed (ω x ) and the effective rolling radius (Re) to determine (S7b) the wheel slip (λ) and / or slip angle ( ).

11. The method according to any one of the preceding claims, further comprising detecting (S8) a tire burst by: comparing the measured distance with an expected distance range (S8a); and A tire burst condition is detected (S8b) when the measured distance is outside the expected distance range within a predefined time period.

12. The method according to any of the preceding claims, further comprising determining (S9) a ground clearance based on the measured distance and a predetermined relationship between the measured distance and a ground clearance of the heavy vehicle (100).

13. A computer program (820) comprising program code means for performing the steps according to any one of claims 1 to 12 when said program is run on a computer or on a processing circuit (810) of a control unit (700).

14. A computer readable medium (810) carrying a computer program (820) comprising program code means for performing the steps according to any one of claims 1 to 12 when the program product is run on a computer or on a processing circuit (810) of a control unit (700).

15. A device for determining at least the effective rolling radius of a tire mounted on a heavy vehicle (100), comprising: A control unit (130; 140; 700), the control unit being configured to: determining a measured distance (d1) between a predefined point of the vehicle (100) and a ground plane (101) supporting the vehicle (100); determining a loaded tire radius of a tire of the vehicle (100) based at least on the measured distance (d1); obtaining a predetermined relationship between a loaded tire radius and an effective rolling radius of the tire; and The effective rolling radius (R) of the tire is determined based on the determined loaded tire radius of the tire and the predetermined relationship between the loaded tire radius of the tire and the effective rolling radius. e ).

16. The device according to claim 15, further comprising at least one radar transceiver (210) arranged to transmit and receive radar signals (115) directed at a known angle (A1) between a vertical plane and a horizontal plane of the heavy vehicle (100), The control unit (130; 140; 700) is configured to determine the measured distance (d1) by adjusting the distance measured by the radar signal (115) by compensating for the known angle (A1).

17. The apparatus according to claim 16, wherein the control unit (130; 140; 700) is configured to obtain the vehicle speed from the at least one radar transceiver.

18. The device according to claim 17, wherein the vehicle speed comprises information about a longitudinal speed of the vehicle (100) and / or a lateral speed of the vehicle (100).

19. An apparatus according to any one of claims 17 to 18, wherein the control unit (130; 140; 700) is further configured to determine a prediction and / or estimate of a road surface roughness and / or a road surface classification based at least on the measured distance and the vehicle speed.

20. The device according to any one of claims 16 to 19, wherein the at least one radar transceiver is mounted at an angle between the vertical plane and the horizontal plane of the heavy vehicle (100).

21. A heavy vehicle (100) comprising a device according to any one of claims 15 to 20.

22. A heavy vehicle (100) according to claim 21, wherein the device comprises at least one radar transceiver, which is arranged to transmit and receive radar signals (115), wherein the at least one radar transceiver is arranged in the direction of the wheel track to which the wheel of the heavy vehicle (100) is to move.

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