Search

EP-4741876-A1 - RADAR-BASED WHEEL MOTION ESTIMATION

EP4741876A1EP 4741876 A1EP4741876 A1EP 4741876A1EP-4741876-A1

Abstract

A system and method are disclosed for determining an absolute slip velocity between a wheel of a vehicle and a ground surface supporting the wheel. They system comprises: one or more wheel-mounted radar sensors configured to receive radio waves reflected from the ground surface; and processing circuitry configured to: determine a Doppler velocity corresponding to the ground surface based on properties of the received radio waves; and determine the absolute slip velocity between the wheel and the ground surface based on the determined Doppler velocity.

Inventors

  • JONASSON, MATS
  • KUMRU, MURAT
  • MARZBANRAD, Alireza
  • RYDSTRÖM, Mats

Assignees

  • Volvo Truck Corporation

Dates

Publication Date
20260513
Application Date
20241107

Claims (15)

  1. A system (300) for determining an absolute slip velocity, Δ v , between a wheel (110) of a vehicle (100) and a ground surface (180) supporting the wheel (100), the system (300) comprising: one or more wheel-mounted radar sensors (302) configured to receive radio waves reflected from the ground surface (180); and processing circuitry (150, 170, 304, 502) configured to: determine a Doppler velocity corresponding to the ground surface (180) based on properties of the received radio waves; and determine the absolute slip velocity, Δ v , between the wheel (110) and the ground surface (180) based on the determined Doppler velocity.
  2. The system (300) of claim 1, wherein the Doppler velocity is measured in a tangential dimension of the wheel (100).
  3. The system (300) of claim 2, wherein the tangential Doppler velocity v doppler,tangential , corresponds to the ground surface (180) and is measured parallel to the ground surface (180).
  4. The system (300) of claim 2, wherein the processing circuitry (150, 170, 304, 502) is further configured to: acquire one or more wheel parameters, wherein the wheel parameters include a rotation angle, θ , of the wheel (110), a rotational speed ω of the wheel (110), a tyre radius r b of the wheel (110), a radial position of the one or more radar sensors (302), and a longitudinal velocity, v x , of the hub (112) of the wheel (110) relative to the ground surface (180); acquire one or more tangential Doppler velocity measurements v doppler,tangential , wherein the number of tangential Doppler velocity measurements v doppler,tangential corresponds to the number of unknown wheel parameters; determine one or more unknown wheel parameters based on the acquired wheel parameters and tangential Doppler velocity measurements, v doppler,tangential ; and determine the absolute slip velocity, Δ v , based on the acquired and determined wheel parameters.
  5. The system (300) of claim 1, wherein the Doppler velocity is measured in a radial dimension of the wheel (110), and the processing circuitry (150, 170, 304, 502) is further configured to: acquire one or more wheel parameters, wherein the wheel parameters include a rotation angle, θ , of the wheel (110), a rotational speed ω of the wheel (110), a tyre radius r b of the wheel (110), and a longitudinal velocity, v x , of the hub (112) of the wheel (110) relative to the ground surface (180); acquire one or more radial Doppler velocity measurements v doppler,radial , wherein the number of radial Doppler velocity measurements v doppler,radial corresponds to the number of unknown wheel parameters; determine one or more unknown wheel parameters based on the acquired wheel parameters and radial Doppler velocity measurements, v doppler,radial ; and determine the absolute slip velocity, Δ v , based on the acquired and determined wheel parameters.
  6. The system (300) of any preceding claim, wherein the Doppler velocity comprises a first Doppler velocity and a second Doppler velocity, and the processing circuitry (150, 170, 304, 502) is configured to: acquire a rotation angle, θ , of the wheel (110); determine a longitudinal velocity, v x , of the hub (112) of the wheel (110) relative to the ground surface (180) using a state-space model based on the acquired first Doppler velocity, second Doppler velocity, and rotation angle, θ ; acquire a belt speed, ω * r , of the wheel (110); and determine the absolute slip velocity, Δ v , by subtracting the longitudinal velocity, v x , from the belt speed, ω * r.
  7. The system (300) of claim 6, wherein the processing circuitry (150, 170, 304, 502) is configured to determine a belt speed, ω * r , of the wheel (110) using the state-space model.
  8. The system (300) of any of claims 4 to 7, wherein the processing circuitry (150, 170, 304, 502) is further configured to: determine a longitudinal slip, s x , acting on the wheel (110) based on the determined absolute slip velocity, Δ v , and the longitudinal velocity, v x ; and/or determine a longitudinal slip, s x , acting on the wheel (110) based on the determined absolute slip velocity, Δ v , and the belt speed, ω * r.
  9. The system (300) of claim 8, wherein the processing circuitry (150, 170, 304, 502) is configured to determine the longitudinal slip, s x , based on the largest of the longitudinal velocity, v x , and the belt speed, ω * r.
  10. A vehicle (100) comprising the system (300) of any preceding claim.
  11. The vehicle (100) of claim 10, wherein the system (300) is mounted in one or more of a tyre (114) or wheel hub (112) of the vehicle (100).
  12. The vehicle (100) of claim 10 or 11, wherein the system (300) is configured to transmit one or more of a determined slip velocity and a longitudinal slip to a controller (140, 160) of the vehicle (100).
  13. A method (400) for determining an absolute slip velocity, Δ v , between a wheel (110) of a vehicle (100) and a ground surface (180) supporting the wheel (110), the method (400) comprising: receiving (402), by one or more wheel-mounted radar sensors (302), radio waves reflected from the ground surface (180); determining (404), by processing circuitry (150, 170, 304, 502) of a computer system, a Doppler velocity corresponding to the ground surface (180) based on properties of the received radio waves; and determining (406), by the processing circuitry (150, 170, 304, 502), the absolute slip velocity, Δ v , between the wheel (110) and the ground surface (180) based on the determined Doppler velocity.
  14. A computer program product comprising program code for performing, when executed by processing circuitry (150, 170, 304, 502), the computer-implemented method (400) of claim 13.
  15. A non-transitory computer-readable storage medium comprising instructions, which when executed by processing circuitry (150, 170, 304, 502), cause the processing circuitry to perform the computer-implemented method (400) of claim 13.

Description

TECHNICAL FIELD The disclosure relates generally to vehicle control. In particular aspects, the disclosure relates to radar-based wheel motion estimation. The disclosure can be applied to heavy-duty vehicles, such as trucks, buses, and construction equipment, among other vehicle types. Although the disclosure may be described with respect to a particular vehicle, the disclosure is not restricted to any particular vehicle. BACKGROUND The dynamics of motion between the wheel of a vehicle and ground surface on which the vehicle is travelling are an important factor in the generation of tyre forces of a vehicle, which provide traction for the vehicle when it is in motion. For example, the relative velocity between the tyre and the ground surface at a contact patch between them has a large influence on traction. This relative velocity is known as the slip velocity or the sliding velocity, and can be used to determine the slip between the wheel and the ground surface, which is a measure of the relative motion between the wheel and the ground surface. The slip velocity and the associated wheel slip can be considered in a planar sense, which is to say in a longitudinal and/or lateral sense, at the contact patch. Knowledge of the slip velocity (and the associated wheel slip) is important for vehicle motion management, in particular to control tyre forces and achieve various objectives relating to, for example, tyre wear, energy efficiency, traction, stability, and comfort. Accurate and reliable estimation of these parameters therefore enables reliable implementation of a large number of vehicle control functions. However, estimating these parameters is challenging. Wheel slip, for example, is considered a so-called "hidden state", which can typically only be observed using high-fidelity simulation tools that provide a high level of detail. Current measurement solutions rely on entities far from the contact patch, while estimation solutions require an estimation of the longitudinal speed of the vehicle and its translation to the wheel hub, which is a significant challenge in itself. Moreover, computing these parameters is numerically sensitive to errors in sensor data and parameter estimations, which can reduce accuracy. It is therefore desired to provide systems, methods and other approaches for vehicle motion estimation that attempt to resolve or at least mitigate one or more of these issues. SUMMARY This disclosure provides systems, methods and other approaches for determining an absolute slip velocity between a wheel of a vehicle and a ground surface on which the vehicle is travelling. The absolute slip velocity is the relative velocity between the tyre and the ground surface supporting the wheel at a contact patch between them. One or more wheel-mounted radar sensors is used to acquire a Doppler velocity corresponding to the ground surface. The Doppler velocity can then be used to determine the absolute slip velocity between the tyre and the ground surface. In some examples, this can be done directly based on the acquired Doppler velocity, while in other examples, motion parameters such as a rotation angle/angular rate of the wheel, a belt speed of the wheel, and a longitudinal velocity of the wheel can be used to determine the absolute slip velocity. The absolute slip velocity can then be used to determine a longitudinal wheel slip value for the wheel, which is a measure of the relative motion between the wheel and the ground surface that can be implemented in vehicle motion control. According to a first aspect of the disclosure, there is provided a system for determining an absolute slip velocity, Δv, between a wheel of a vehicle and a ground surface supporting the wheel, the system comprising: one or more wheel-mounted radar sensors configured to receive radio waves reflected from the ground surface; and processing circuitry configured to: determine a Doppler velocity corresponding to the ground surface based on properties of the received radio waves; and determine the absolute slip velocity, Δv, between the wheel and the ground surface based on the determined Doppler velocity. The first aspect of the disclosure may seek to provide a more accurate and reliable estimation of absolute slip velocity, and therefore longitudinal wheel slip, that can be implemented in vehicle motion control. Accurate determination of these parameters is important for vehicle motion management, in particular to control tyre forces and achieve various objectives. The estimation is provided using a system in the vicinity of the contact patch between the tyre and the ground surface, and can be achieved by determining an accurate estimation of the longitudinal speed of (the wheels of) the vehicle. Optionally in some examples, including in at least one preferred example, the Doppler velocity is measured in a tangential dimension of the wheel. A technical benefit may include that a particular type of radar sensor can be used in the estima