EP3887221A1

EP3887221A1 - Method and control unit for operating a vehicle

Info

Publication number: EP3887221A1
Application number: EP19805152.6A
Authority: EP
Inventors: Timo Koenig; Markus Rall; Hans-Markus Bussenius; Helge Frauenkron; Robert Kuenne; Simon Weissenmayer; Waldemar Haas; David Becker
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2018-11-26
Filing date: 2019-11-07
Publication date: 2021-10-06
Also published as: WO2020108940A1; DE102018220259A1; CN113165659A

Abstract

The present invention relates to a method for operating a vehicle (100), in which road condition information (106) representing a coefficient of friction of a road in the region of the vehicle (100) is read in by an ultrasound sensor system (104) of the vehicle (100) and an adhesion limit (112) of at least one wheel of the vehicle (100) is determined using the road condition information (106), wherein a response behaviour of the vehicle (100) is influenced using the adhesion limit (112).

Description

description

Method and control device for operating a vehicle

Field of the Invention

The invention relates to a method and a control device for operating a vehicle

State of the art

If a wheel of a vehicle loses grip and slips, torque on the wheel can be reduced to that

To restore traction. A speed of the wheel can be monitored via sensors. A corresponding system can be referred to as an anti-lock system or anti-slip control.

Disclosure of the invention

Against this background, the approach presented here becomes a method for operating a vehicle, a corresponding control unit, and finally a corresponding computer program product and a

machine-readable storage medium presented according to the independent claims. Advantageous further developments and improvements of the approach presented here result from the description and are described in the dependent claims.

Advantages of the invention Embodiments of the present invention can advantageously make it possible to influence driving behavior of a vehicle in a preventive manner in such a way that the wheels of the vehicle are prevented from slipping even in poor weather-related road conditions. This can improve driving stability of the vehicle and the safety of vehicle occupants

A method for operating a vehicle is proposed in which road condition information representing a coefficient of friction of a road in the area of the vehicle is read in by an ultrasound sensor system of the vehicle and an adhesion limit of at least one wheel of the vehicle is determined using the road condition information, a

Responsiveness of the vehicle is influenced using the adhesion limit.

Ideas for embodiments of the present invention can be viewed, inter alia, as based on the thoughts and knowledge described below.

A road's coefficient of friction is essentially determined by a road's surface condition due to wetness, mud, leaves or snow or the like influenced. Wetness in particular can be detected by an ultrasonic sensor system. The coefficient of friction can be determined or estimated depending on how much water is recognized on the road. The

The amount of water can be recognized, for example, by evaluating a noise level. The noise level represents a volume or intensity of background noise, which is detected by an ultrasonic sensor. A rolling noise of tires is already significantly increased, for example, when the road is only slightly moistened, and thus also increases the volume of the background noise. The noise level generally gets higher the wetter the road is.

An adhesion limit can be a maximum transferable frictional force between a wheel and a surface. The adhesion limits of the wheels of a vehicle can differ from wheel to wheel. When determining the respective detention limit, individual factors can be taken into account. The

Responsiveness can therefore also be influenced individually for each wheel. The Responsiveness can be influenced in such a way that a friction force required on the wheel is less than the maximum transferable friction force.

The maximum transferable frictional force or adhesion limit can depend on the direction. For example, the grip limit may be higher in a rolling direction of the wheel than in a transverse direction.

The grip limit can also be determined using a wheel contact force of the wheel. A wheel contact force can depend on a load on the vehicle. The wheel contact force can be measured by a sensor. The wheel contact force can also be dependent on an acceleration acting on the vehicle. For example, the wheel contact force on wheels on the outside of the curve can be greater than on wheels on the inside of the curve.

The grip limit can also be determined using tire condition information of a tire of the wheel. The adhesion limit can depend on the type and condition of the tire. For example, a

Winter tires have a higher grip limit in the cold than summer tires. Tire depth can also affect the grip limit. An air pressure prevailing in the tire can also influence the grip limit. A tire can age and lose grip. Tire condition information may include information about the tire. For example, the

Map tire condition information, the type of tire, its age and / or the tread depth. An air pressure prevailing in the tire can be detected by means of a sensor.

A drag torque on the wheel can be limited to keep a resulting frictional force below the stick limit. A drag torque brakes the vehicle. For example, an electric machine can be operated as a generator by the drag torque. An internal combustion engine can also generate the drag torque, for example, through frictional forces. If the drag torque is too high, a wheel can slip. The drag torque can be reduced by burning more fuel efficiently.

By limiting the drag torque, the driving stability of the

Vehicle can be increased.

A drive torque on the wheel can be limited to keep the resulting frictional force below the stick limit. A drive torque accelerates that Vehicle or counteracts driving resistance. If the drive torque is too high, a wheel can spin. The driving stability of the vehicle can be increased by limiting the drive torque.

A speed change limit of the wheel can be adjusted using the grip limit to keep the resulting frictional force below the grip limit. A speed change limit defines how fast a wheel can become faster or slower. If the wheel becomes faster or slower too quickly, it can slip or spin. By setting the

Speed change limits can increase the driving stability of the vehicle.

A jerk limit can be set using the grip limit to keep the resulting frictional force below the grip limit. The jerk is one

Change in acceleration. If the jerk is too great, a wheel may slip or spin. The driving stability of the vehicle can be increased by setting the jerk limit.

A slip angle of the wheel can be limited to keep the resulting frictional force below the stick limit. If the slip angle is too large, the vehicle can understeer and slide over the front axle. Limiting the slip angle can improve the cornering stability of the vehicle.

Gear shift speed thresholds can be set using the adhesion limit to reduce the resulting frictional force under the

To hold the limit of detention. A gear change speed threshold may be a threshold at which one changes from one gear to the next. The speed change speed thresholds can be lower

Adhesion limit can be lowered to change to a higher gear at lower speeds, which can limit the torque on driven wheels.

The method can be implemented, for example, in software or hardware or in a mixed form of software and hardware, for example in a control unit. The approach presented here also creates a control device which is designed to carry out the steps of a variant of the method presented here

to carry out, control or implement appropriate facilities.

The control device can be an electrical device with at least one computing unit for processing signals or data, at least one storage unit for storing signals or data, and at least one interface and / or a communication interface for reading or outputting data which are embedded in a communication protocol, be. The computing unit can, for example, be a signal processor, a so-called system ASIC or a microcontroller for processing sensor signals and outputting

Data signals depending on the sensor signals. The storage unit can be, for example, a flash memory, an EPROM or a magnetic storage unit. The interface can be used as a sensor interface for reading the sensor signals from a sensor and / or as an actuator interface

Output of the data signals and / or control signals to an actuator. The communication interface can be designed to read in or output the data wirelessly and / or via line. The

Interfaces can also be software modules that are present, for example, on a microcontroller alongside other software modules.

Also advantageous is a computer program product or computer program with program code, which can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and for carrying out, implementing and / or controlling the steps of the method according to one of the above

described embodiments is used, in particular when the program product or program is executed on a computer or a device.

It is noted that some of the possible features and advantages of the invention are described herein with respect to different embodiments. A person skilled in the art will recognize that the features of the control device and the method are combined, adapted or appropriately

can be exchanged in order to arrive at further embodiments of the invention. Brief description of the drawing

Embodiments of the invention are described below with reference to the accompanying drawing, wherein neither the drawing nor the description are to be interpreted as limiting the invention.

1 shows an illustration of a vehicle with a control device according to an exemplary embodiment.

The figure is only schematic and not to scale. Same

In the figure, reference symbols designate identical or equivalent features.

Embodiments of the invention

1 shows a representation of a vehicle 100 with a control device 102 according to an exemplary embodiment. The control device 102 is equipped with a

Ultrasonic sensor system 104 of the vehicle 100 connected. The

Ultrasonic sensor system 104 provides road condition information 106. The road condition information 106 is determined by evaluating at least one noise level 108 recorded on the vehicle 100. The

Road condition information 106 maps whether the road is in the area of the

Vehicle 100 is damp, wet or flooded.

If the road is damp, wet or flooded, it has a lower coefficient of friction than the same road when it is dry. Therefore, a wheel can transfer less friction to the road when the road is damp, wet, or flooded. It is irrelevant whether longitudinal forces for acceleration or deceleration or lateral forces for steering or keeping in lane are considered.

The transferable longitudinal forces are generally somewhat larger than the lateral forces, even on dry roads.

In the control device 102, the

Road condition information 106 evaluated and one for each wheel

Adhesion limit 112 determined per wheel of vehicle 100. A

Influencer 114 uses the adhesive limits 112 to make a Influence response behavior of the vehicle 100. The

Influencing device 114 intervene in a driving dynamics of vehicle 100 in order to keep the frictional forces on the wheels smaller than the adhesion limit 112.

In the approach presented here, vehicle behavior is influenced as a function of a water level on the roadway measured using ultrasound.

A measurement of the road condition with the aid of a noise level 108 is possible. The higher the own vehicle speed, the greater the measured noise level 108 which the own vehicle 100 emits and which is measured by the ultrasonic sensors (USS).

Moisture on the road can be detected with the help of ultrasonic sensors. As an alternative or in addition, wetness information 116 can be received via radio interface.

With the help of wetness information 116 or

Road condition information 112 optimizes the driving behavior of vehicle 100.

Using ultrasound sensors, it is measured whether the road is wet or dry, and based on the vehicle speed, the

Tire quality and the forces acting on the wheels are assessed as to whether one of the wheels is reaching the grip limit 112. Depending on the measurement and assessment, the forces acting on the wheels are limited.

In one embodiment, the maximum permissible when wet

Recuperation torque reduced to such an extent that there is no fear of a negative impact on vehicle stability. Recuperation is prevented if there is a risk of aquaplaning. This increases the stability of the vehicle 100.

In one embodiment, the drag torque of the

Internal combustion engine reduced on wet roads and when threatened

Aquaplaning risk completely compensated. Noticeable interventions are combined with information to the driver. This increases the stability. In addition, the braking torque on the rear wheels is reduced to a minimum and a gear change is blocked to apply moments to the Avoid drivetrain (positive and negative). This also increases the stability of the vehicle 100.

In one embodiment, the speed change limit prevents the tires from spinning or blocking. This will be

Speed change limit chosen so that the speed can only increase as quickly as would be possible with frictional engagement and dry or wet road surface. The speed change limit is therefore chosen higher on dry roads and lower on wet roads. As a result, the vehicle 100 can be accelerated faster.

In one embodiment, the maximum jerk limit is chosen higher on a dry road than on a wet road. A large jerk or a large change in the torque can lead to the vehicle 100 becoming unstable. This limits the risk of the vehicle 100 becoming unstable on a wet road, while optimal response is ensured on a dry road.

In one embodiment, the transmission shifts into higher gears earlier when accelerating on wet roads than when on dry roads. Conversely, it later shifts into lower gears when braking. The ratio gear to speed g / v from selected gear g based on the

Vehicle speed v is selected higher on a wet road than on a dry road. This increases efficiency and vehicle stability.

In one embodiment, the steering control device limits the maximum slip angle. This means that a counter torque is applied to the steering in order to reduce excessive steering. This enables tighter curve radii and increases stability.

The approach presented here increases energy efficiency and it can be accelerated faster, whether wet or dry. Furthermore, the vehicle 100 behaves more stably and safely.

In conclusion, it should be noted that terms such as "showing",

"Comprehensive", etc. do not exclude other elements or steps and terms such as "a" or "an" do not exclude a variety. Reference signs in the claims are not to be viewed as a restriction.

Claims

Expectations

1. A method for operating a vehicle (100), in which a

Friction coefficient of a road in the area of the vehicle (100) representing road condition information (106) is read in by an ultrasound sensor system (104) of the vehicle (100) and an adhesion limit (112) of at least one wheel of the vehicle (100) using the

Road condition information (106) is determined using a

Responsiveness of the vehicle (100) is influenced using the adhesion limit (112).

2. The method of claim 1, wherein the adhesion limit (112) is further determined using a wheel contact force of the wheel.

3. The method according to any one of the preceding claims, wherein the

Adhesion limit (112) is further determined using tire condition information of a tire of the wheel.

4. The method according to any one of the preceding claims, in which a

Drag torque on the wheel is limited to keep a resulting frictional force below the sticking limit (112).

5. The method according to any one of the preceding claims, in which a

Drive torque on the wheel is limited to keep the resulting frictional force below the sticking limit (112).

6. The method according to any one of the preceding claims, in which a

Speed change limit of the wheel is set using the grip limit (112) to keep the resulting frictional force below the grip limit (112).

7. The method according to any one of the preceding claims, in which a

Jerk limit is set using the adhesive limit (112) to keep the resulting friction force below the adhesive limit (112).

8. The method according to any one of the preceding claims, wherein a slip angle of the wheel is limited in order to keep the resulting frictional force below the adhesion limit (112).

9. The method according to any one of the preceding claims, in which

Gear change speed thresholds are set using the grip limit (112) to keep the resulting frictional force below the grip limit (112).

10. Control device (102) which is designed to execute, implement and / or control the method according to one of the preceding claims in corresponding devices.

11. Computer program product which is set up to carry out, implement and / or implement the method according to one of claims 1 to 9

head for.

12. Machine-readable storage medium on which the

Computer program product according to claim 11 is stored.