DE102022204541B3 - Method for determining the condition of a vehicle's tires and a system - Google Patents

Abstract

System (10) for determining the condition of the tires of a vehicle (1) with at least one controller (4) in the vehicle (1), which performs calculations and can establish a connection via a communication network (3) to a stationary server (2), wherein at least one coefficient of friction estimator (7, 7A) is present for estimating a coefficient of friction between a tire of the vehicle (1) and the road surface and/or a rolling resistance estimator (8) which determines the coefficient of rolling resistance from the equation of motion of the vehicle and data at least on Controller (4) transmitted

Description

The invention relates to a method for determining the condition of the tires of a vehicle and a system for carrying out the method.

State of the art

In modern vehicles, a large amount of data and information is collected and processed at various points. In addition to various safety aspects, it is important for a driver or a fleet manager to know the condition of the vehicle's tires.

DE 10 2020 113 937 A1 Fig. 12 shows a system for determining a tire condition including an external information obtaining section, a friction coefficient estimating section, and a tire condition determining section. The external information acquiring section is configured to acquire external information about a disturbance factor affecting a condition of a road surface on which a target vehicle is running. The friction coefficient estimating section is configured to estimate a friction coefficient between a tire of the target vehicle and the road surface based on driving information about a driving condition of the target vehicle. The tire condition determining section is configured to determine a slip of the tire of the target vehicle based on a reference value indicating the slip of the tire according to the external information and the friction coefficient estimated by the friction coefficient estimating section. Aging deterioration data represents the transition of the slip ratio over time, particularly the transition of the slip ratio in the earlier years. The slip ratio increases over the runtime. That is, traction performance gradually deteriorates.

DE 10 2018 215 170 A1 shows a method for exchanging friction coefficient data in fleet operation of vehicles. Here, collected friction coefficient data are used to generate a friction coefficient correction factor and thus provide improved data for the operation of another vehicle.

Individual values for the tires such as a statement about the age-related decrease in the coefficient of friction due to aging of the rubber compound and the rolling resistance of the tire are not used.

The object of the invention is to create a method and a system that can make a reliable statement about the condition of the tires using the available data and additional external information.

Description of the invention

The object is achieved with a system for determining the condition of the tires of a vehicle with at least one controller in the vehicle, which performs calculations and can establish a connection via a communication network with a stationary server, with at least one friction value estimator for estimating a friction coefficient between a tire of the vehicle and the road surface and a rolling resistance estimator, which determines the rolling resistance coefficient from the vehicle's equation of motion, and transmits data at least to the controller.

The driver and/or the fleet operator is informed if the tires need to be changed because the tires no longer have enough grip due to aging.

A first friction value estimator evaluates the slip of the tire on the road surface and a second optically based friction value estimator evaluates the road surface.

The two different ways of determining tire aging make it even more reliable.

The evaluation of the two friction value estimators and the analysis of the vehicle's internal data take place in the vehicle's controller and/or after the data has been transmitted to the server. The evaluation of the coefficient of friction and rolling resistance is independent of one another and can therefore also be carried out in a distributed manner.

This can be used to represent an in-vehicle system or a network-based system.

Measurements from other friction value estimators from a fleet of vehicles can also be processed in the server.

The rolling resistance coefficient is advantageously determined by estimating an equation of motion for the vehicle.

The method according to the invention for determining the condition of the tires of a vehicle runs in the system, with measurements taking place on the vehicle side, with the measurements being compared with one another and the result being communicated to at least the driver via a data output unit if the two independent estimates come to the same result.

Advantageously, the measurements are re-triggered at specified repetitions until there is a match or the driver is informed of the divergent result after the repetitions have elapsed.

Measurements can be improved by taking weather data into account. In one embodiment, the measurements are compared with the vehicle's original data or with comparison data from other vehicles.

The data is output to at least the driver with messages from the group: status display, advertising tire comparison, forecast of energy savings.

character list

• 1 shows a schematic system for detecting the condition of the tires of a vehicle,
• 2 shows units in the vehicle with friction estimator and rolling resistance estimator,
• 3 shows alternative units in the vehicle,
• 4 shows another alternative solution.

1 FIG. 12 is a block diagram showing a schematic overall configuration of a tire condition determination system 10 according to a first embodiment.

As in 1 As shown, the system 10 for determining a tire condition includes a vehicle 1 whose driver wants to determine his tire condition. Other vehicles 1 'represent vehicles of a fleet or a predefined group for comparison.

An external server 2 is connected to the vehicle 1 and the plurality of other vehicles 1' via a wireless communication network 3 and collects data of the vehicles 1, 1'.

The communication network can be a cellular network or a near-field network via RFIDs or Bluetooth et al.

At least one controller 4 is available in the vehicle 1, which carries out the calculation steps for carrying out the determination of the condition of the tires of the vehicle.

2 FIG. 1 schematically shows a vehicle 1 in which the at least one controller is available.

The controller 4 receives data from a data input unit 5 and presents the results with a data output unit 6. The data output unit 6 can be a monitor in the vehicle or a connection to the communication network for forwarding the information to the server 2 and from there to other applications. A connection to an application on a mobile radio device is preferred.

The data input unit 5 receives data from a first tire friction value estimator 7. The friction value information between the road and the tires is determined using a suitable determination method on the vehicle that measures slip.

In a first embodiment, the coefficient of friction information of the vehicle 1 and the vehicles 1' of a fleet at the same GPS positions are requested from the server 2 at the same time. The vehicles 1, 1 'and the associated controller 3 start measuring the slip z. B. with a method for estimating the coefficient of friction with a brace of two electric axles or the brace of an electric axle with a braked normal axle. The data are transmitted via the communication network 3 to the server 2, which then compares the values.

In order to allow a static evaluation, a large number of friction coefficient estimates must be available, which are collected over a longer period of time, for example over weeks.

The statistical evaluation takes place on the server. The result is sent back to vehicle 1 as a status. If it is found that the tires of the vehicle 1 have a lower coefficient of friction or the coefficient of friction has decreased significantly over time compared to the other vehicles 1′, it can be concluded that the tires are too old and need to be replaced. The status transmission then contains a warning to the driver and/or to the fleet operator.

Since the tread depth can be checked by the end customer/fleet operator, but not whether the tire is losing grip due to aging, you can give him an important indication of the quality of his tires.

In a further embodiment, not only status information is generated, but the driver of the vehicle 1 or the fleet operator is shown how much the consumption of the vehicle can be reduced by new tires due to the reduction in rolling resistance and the range gain by the new tires is calculated. The usage profile can be determined from the speed curves of the vehicles and, in turn, the energy savings can be determined from this. Taking into account current prices for energy, the end user / Flot ten operators can also be directly given a payback period for a new tire with higher efficiency.

The comparison is calculated in server 2. The comparison can either be carried out in relation to a modern average tire or accesses parameters of a defined tire model from a tire manufacturer.

The advantages of a current tire model with regard to the rolling resistance could be shown and advertised via an advertising function 11 even in a cooperation with a tire manufacturer. The tire parameters provided by the tire manufacturer can be used to improve the estimation of the coefficient of friction and the calculation of the rolling resistance.

As an alternative to comparing the coefficient of friction information with other vehicles, as in 3 shown, in a further embodiment, the information from a camera or lidar-based friction value estimator 7A can be compared with a slip-based friction value estimator 7 . For this purpose, the roadway situation is assessed with the non-slip-based friction value estimator 7A. If the friction value situation can be estimated precisely, for example a specific dry asphalt at a specific temperature, this friction value estimator supplies an expected target friction value.

This setpoint coefficient of friction is then compared with the coefficient of friction of the measurement based on slip. Both values are recorded in vehicle 1 and processed in controller 2. If a trend can be seen that the slip-based coefficient of friction decreases over the service life compared to the "contactless" coefficient of friction, this can be traced back to a deteriorated tire, either the status is communicated only to the driver of the vehicle 1 via the data output unit 6 or to the fleet operator sent via the communication network 3.

Since daily and seasonal effects such as temperature, road surface conditions, pollen dust, etc. influence the result, the observation period for this method is long.

A rolling resistance estimator is used to determine tire efficiency.

The rolling resistance estimator is based on an equation for the forces acting on a vehicle. The total force on the vehicle F _drive consists of the driving force of a motor A, the rolling resistance B*v consisting of a rolling resistance coefficient B multiplied by the speed v, the air resistance value C*v ² and a term m* a that multiplies the mass with an acceleration contains. $${\text{f}}_{\text{drive}}=\text{A}+\text{B}*\text{v}+\text{C}*{\text{<figure-callout id="2" label="v" filenames="DE102022204541B3\_0002.png,DE102022204541B3\_0005.png" state="{{state}}">v</figure-callout>}}^2+\text{m}*\text{a}\text{.}$$

The solution of the differential equation based on measurements of the force Fdrive, the speed v and the acceleration a, and estimates the constants of the driving resistance equation A, B, C and m in an iterative process.

The coefficient B largely reflects the rolling resistance of the tyres. The rolling resistance of the tires can therefore be determined from this.

The rolling resistance coefficient B is then compared locally in the vehicle 1 with the characteristic values of new tires.

Since both measurements by the rolling resistance estimator 8 and the friction value estimator 7 are used independently of one another, the result must be compared in the controller 4 . If the status result is the same, for example if the tires need to be replaced, the information is forwarded to the data output unit. If the two measurements do not come to the same result, the measurement and the evaluation are repeated x times. If there is still no joint result after the umpteenth repetition, the driver will be informed.

Interfering influences that negatively affect the quality of the rolling resistance calculation are wet roads, wind and slipstream effects. Slipstream effects can be corrected by sensors that are already in the vehicle recognizing whether the vehicle is in the slipstream of a vehicle ahead, e.g. distance cruise control, ADAS camera information.

To reduce wind influences, weather information 9 is used, which is made available to the controller 4 via the server 2 in order to identify whether disturbing wind occurs on the day. Since the condition of the tires does not have to be determined continuously, the evaluation can simply be omitted on windy days. The same applies, for example, to effects such as changed rolling resistance due to wet roads.

If the tire efficiency class of the tire is known because a tire identifier is transmitted to the controller or the cloud, this can also be used to estimate the tire efficiency. The information about which tires are on the vehicle can either be sent from the tire to the vehicle, entered by the driver via an application in the vehicle or on a mobile phone, or stored in the vehicle (by the vehicle manufacturer for the first tires, or workshop after tire change).

Claims (10)

System (10) for determining the condition of the tires of a vehicle (1) with at least one controller (4) in the vehicle (1), which performs calculations and can establish a connection via a communication network (3) to a stationary server (2), wherein at least one coefficient of friction estimator (7, 7A) for estimating a coefficient of friction between a tire of the vehicle (1) and the road surface and a rolling resistance estimator (8) which determines the coefficient of rolling resistance (B) from the equation of motion of the vehicle is present and data at least on transmitted to the controller (4). system (10) according to claim 1 , characterized in that a first friction value estimator (7) detects the slippage of the tire on the road surface and a second friction value estimator (7A) evaluates the road surface on an optical basis. system (10) according to claim 1 or 2 , characterized in that the evaluation of the two friction value estimators (7, 7A) and the analysis of the vehicle-internal data takes place in the controller (4) of the vehicle and/or after transmission of the data in the server (2). System (10) according to one of the preceding claims, characterized in that measurements of further friction value estimators from a fleet of vehicles (1') can be processed in the server (2). System (10) according to one of the preceding claims, characterized in that the rolling resistance coefficient (B) occurs via an estimation of an equation of motion of the vehicle (1). Method for determining the condition of the tires of a vehicle in a system (10). claim 1 , measurements being carried out on the vehicle side, the measurements being compared with one another and the result being communicated to at least the driver via a data output unit (6) if the two independent measurements come to the same result. procedure after claim 6 , where the measurements are re-triggered at fixed iterations until there is a match, or the driver is informed of the divergent result after the iterations have elapsed. Procedure according to one of Claims 6 or 7 , data of the measurements being improved by taking weather data (9) into account. Procedure according to one of Claims 6 until 8th , The measurements being compared with the original data of the vehicle (1) or with comparative data from other vehicles (1'). Procedure according to one of Claims 6 until 9 , wherein the data output unit sends messages to at least the driver from the group: status display, promotional tire comparison, prediction of energy savings in the event of re-equipment.

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