Device and method for automatic detection of road conditions for vehicle applications

Patent metadata

Field	Value
Publication number	US-12441324-B2
Application number	US-202217871463-A
Country	US
Kind code	B2
Filing date	Jul 22, 2022
Priority date	Aug 10, 2021
Publication date	Oct 14, 2025
Grant date	Oct 14, 2025

Abstract

A road condition detection device, to be coupled to the wheel of a vehicle, is provided with: an electrostatic charge variation sensor, to provide a charge variation signal indicative of an electrostatic charge variation associated with the rotation of the wheel; and a processing unit, coupled to the electrostatic charge variation sensor to receive the charge variation signal and furthermore for receiving a rotation speed signal indicative of the rotation speed of the wheel. In particular, the processing unit jointly processes the rotation speed signal and the charge variation signal to detect a road condition of a wet road condition and a dry road condition.

First claim

The invention claimed is:

1. A road condition detection device, configured to be coupled to a wheel of a vehicle and to a vehicle controller, the road condition detection device comprising:
an electrostatic charge variation sensor, which, in operation, provides a charge variation signal indicative of an electrostatic charge variation associated with rotation of the wheel; and
processing circuitry, coupled to the electrostatic charge variation sensor, wherein the processing circuitry, in operation, receives the charge variation signal, and receives a rotation speed signal indicative of the rotation speed of the wheel,
wherein the processing circuitry, in operation, jointly processes the rotation speed signal and the charge variation signal to detect a road condition between a wet condition and a dry condition based on an amplitude of the charge variation signal and on the rotation speed signal, wherein the processing circuitry, in operation:
determines, in a trend in a frequency domain of the charge variation signal, a peak amplitude of a fundamental frequency at the rotation speed of the wheel;
compares the peak amplitude with a threshold amplitude to determine one of the dry road condition and the wet road condition;
determines a frequency distance between the fundamental frequency and a frequency associated with the rotational speed of the wheel;
compares the frequency distance with a threshold distance to determine the one of the dry road condition and the wet road condition;
determines the dry road condition in response to the frequency distance being less than the threshold distance and the peak amplitude being greater than the threshold amplitude;
determines the wet road condition in response to the frequency distance not being less than the threshold distance or the peak amplitude not being greater than the threshold amplitude;
generates a vehicle control signal indicative of the determined road condition; and
provides the generated vehicle control signal to the vehicle controller to control one or more vehicle control systems coupled to the vehicle controller.

2. The device according to claim 1 , comprising an analog to digital converter coupled between the electrostatic charge variation sensor and the processing circuitry, the electrostatic charge variation sensor including a first operational amplifier and a second operational amplifier coupled to respective inputs of the analog to digital converter.

3. The device according to claim 1 , comprising a rotation speed sensor, which, in operation, provides the rotation speed signal.

4. The device according to claim 3 , wherein the rotation speed sensor is a MEMS triaxial gyroscope; and wherein the processing circuitry, in operation, determines the rotation speed of the wheel as a function of a modulus of an angular speed signal provided by the gyroscope.

5. The device according to claim 3 , wherein the charge variation sensor comprises:
a detection electrode, which, in operation, detects electrostatic charge variation;
a high-impedance instrumentation amplifier having an input coupled to the detection electrode; and
an analog-to-digital converter coupled to an output of said instrumentation amplifier to provide the charge variation signal.

6. The device according to claim 3 , comprising a chip that includes the processing circuitry, the rotation speed sensor and the electrostatic charge variation sensor.

7. The device according to claim 1 , wherein the processing circuitry, in operation:
performs a transform in the frequency domain to obtain the charge variation signal in the frequency domain;
performs a peak identification operation in the frequency domain in the charge variation signal, to obtain a series of identified peaks, each at an associated frequency;
determines frequency distances between each of the identified peaks and a frequency corresponding to the rotation speed of the wheel; and
selects the peak with a minimum distance with respect to the frequency corresponding to the rotation speed of the wheel and determines the amplitude of the selected peak as the peak amplitude of the fundamental frequency.

8. The device according to claim 1 , wherein the processing circuitry, in operation:
compares the rotation speed with a minimum-speed threshold; and
continues detection of road conditions in response to the rotation speed being higher than the minimum-speed threshold.

9. A vehicle system, comprising:
a wheel;
a detection device coupled to the wheel, the detection device including:
a rotation sensor, which, in operation, detects a rotational speed of the wheel;
a charge variation sensor, which, in operation, generates a charge variation signal; and
processing circuitry coupled to the rotation sensor and to the charge variation sensor, wherein the processing circuitry, in operation, determines a wet or dry road condition based on an amplitude of the charge variation signal and the rotational speed of the wheel and generates a control signal indicative of the determined road condition; and

a main controller coupled to the processing circuitry, wherein the main controller, in operation, receives the control signal indicative of the determined road condition and generates, in response to the received control signal, vehicle control signals to control one or more vehicle control systems coupled to the main controller, wherein the processing circuitry, in operation:
determines, in a trend in a frequency domain of the charge variation signal, a peak amplitude of a fundamental frequency at the rotation speed of the wheel;
compares the peak amplitude with a threshold amplitude to determine one of the dry road condition and the wet road condition;
determines a frequency distance between the fundamental frequency and a frequency associated with the rotational speed of the wheel;
compares the frequency distance with a threshold distance to determine the one of the dry road condition and the wet road condition;
determines the dry road condition in response to the frequency distance being less than the threshold distance and the peak amplitude being greater than the threshold amplitude; and
determines the wet road condition in response to the frequency distance not being less than the threshold distance or the peak amplitude not being greater than the threshold amplitude.

10. The system of claim 9 , wherein the processing circuitry, in operation, compares a rotation speed value with a minimum-speed threshold and continues to detect the road condition in response to the rotation speed value being higher than the minimum-speed threshold.

11. A method, comprising:
generating, by an electrostatic charge variation sensor, a charge variation signal indicative of an electrostatic charge variation associated with rotation of a wheel of a vehicle; and
receiving, by processing circuitry coupled to the electrostatic charge variation sensor, the charge variation signal and a rotation speed signal indicative of a rotation speed of the wheel;
detecting a road condition using the processing circuitry by processing the rotation speed signal and the charge variation signal, wherein the processing comprises:
determining, in a trend in a frequency domain of the charge variation signal, a peak amplitude of a fundamental frequency at the rotation speed of the wheel;
comparing the peak amplitude with a threshold amplitude to determine one of a dry road condition and a wet road condition;
determining a frequency distance between the fundamental frequency and a frequency associated with the rotational speed of the wheel;
comparing the frequency distance with a threshold distance to determine the one of the dry road conditi

Assignees

• St Microelectronics Srl

Inventors

• Passaniti Fabio
• Alessi Enrico Rosario

Classifications

• G01R29/24

  Arrangements for measuring quantities of charge · CPC title

• G01R29/12

  Measuring electrostatic fields {or voltage-potential} · CPC title

• B60W40/105

  Speed · CPC title

• B60T2210/12

  Friction · CPC title

• B60T8/172

  Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters {(B60T8/17551 takes precedence)} · CPC title