CN113165659A

CN113165659A - Method and control unit for operating a vehicle

Info

Publication number: CN113165659A
Application number: CN201980077862.5A
Authority: CN
Inventors: T·柯尼希; M·拉尔; H-M·布塞纽斯; H·弗劳恩克龙; R·金内; S·魏森迈尔; W·哈斯; D·贝克尔
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2018-11-26
Filing date: 2019-11-07
Publication date: 2021-07-23
Also published as: EP3887221A1; DE102018220259A1; WO2020108940A1

Abstract

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

Description

Method and control unit for operating a vehicle

Technical Field

The invention relates to a method and a controller for operating a vehicle.

Background

When the wheels of the vehicle lose ground adhesion and slip occurs, the torque on the wheels may be reduced to restore ground adhesion. For this purpose, the rotational speed of the wheel can be monitored by means of a sensor. The corresponding system may be referred to as an anti-lock system or anti-slip control.

Disclosure of Invention

Against this background, the invention proposed herein proposes a method for operating a vehicle, a corresponding controller, a corresponding computer program product and a machine-readable memory medium according to the independent claims. Advantageous embodiments and improvements of the invention proposed here emerge from the description and are specified in the dependent claims.

Embodiments of the invention can be implemented in an advantageous manner in which the driving behavior of the vehicle is influenced preventively in such a way that the wheels of the vehicle are protected against slipping even in the case of poor weather-dependent road conditions. Thereby, the running stability of the vehicle and the safety of the vehicle occupant can be improved.

A method for operating a vehicle is proposed, in which method road state information representing a friction value of a road in a vehicle region is read in from an ultrasonic sensor system of the vehicle and an adhesion limit of at least one wheel of the vehicle is determined using the road state information, wherein a response behavior of the vehicle is influenced using the adhesion limit.

Further, the idea of the embodiment of the present invention can be considered to be based on the idea and knowledge explained below.

The friction value of a road is mainly influenced by the surface properties of the road based on moisture, dirt, leaves or snow or the like. In particular, wetness can be recognized by the ultrasonic sensor system. The friction value may be determined or estimated based on how much water is identified on the road. For example, the amount of water may be identified by an analytical evaluation of the noise level. The noise level here reflects the sound intensity or intensity of the background noise sensed by the ultrasonic sensor. For example, in the case of a road that is only slightly wet, the rolling noise of the tire is already significantly increased and therefore also the sound intensity of the background noise. In general, the more humid the road, the higher the noise level becomes.

The traction limit may be the maximum transferable friction between the wheel and the ground. The adhesion limit of the wheels of the vehicle may differ individually from wheel to wheel. Thus, individual factors for each wheel may be considered in determining each adhesion limit. Thus, the response behavior can also be influenced individually per wheel. The response behavior can be influenced in such a way that the required friction force at the wheel is less than the maximum transferable friction force.

The maximum transferable friction or adhesion limit may be direction-dependent. For example, the adhesion limit may be higher in the rolling direction of the wheel than in the lateral direction.

Furthermore, the adhesion limit may be determined using the wheel support force of the wheel. The wheel support force may depend on the load of the vehicle. The wheel support force may be measured by a sensor. The wheel support force may also depend on the acceleration acting on the vehicle. For example, the wheel support force may be greater at the wheels outside the curve than at the wheels inside the curve.

Further, the adhesion limit may be determined using the tire condition information of the tire of the wheel. The adhesion limit may depend on the type and state of the tire. For example, winter tires in cold conditions may have a higher adhesion limit than summer tires. The tread depth of the tire may also affect the adhesion limit. The air pressure prevailing in the tire may also influence the adhesion limit. The tire may age and lose adhesion. The tire condition information may contain information about the tire. For example, the tire condition information may reflect the type of tire, the age of the tire, and/or the tread depth. The air pressure prevailing in the tire can be sensed by means of a sensor.

The drag torque at the wheels may be limited in order to keep the resulting friction below the adhesion limit. The drag torque brakes the vehicle. For example, the electric machine can be operated as a generator by means of a drag torque. For example, the internal combustion engine may also generate a drag torque by friction. In case the drag torque is too high, the wheels may slip. The drag torque can be reduced in such a way that more fuel is instantaneously and efficiently burned. The driving stability of the vehicle can be improved by limiting the dragging torque.

The drive torque on the wheels may be limited in order to keep the resulting friction below the adhesion limit. The driving torque accelerates the vehicle or resists the running resistance. In case the drive torque is too high, the wheels may slip. The driving stability of the vehicle can be improved by limiting the driving torque.

The limit of the change in rotational speed of the wheels may be adjusted using the adhesion limit to keep the resulting friction below the adhesion limit. The speed variation limit defines: how quickly the wheel is allowed to become faster or slower. If a wheel becomes faster or slower too quickly, the wheel may spin or slip. The running stability of the vehicle can be improved by adjusting the rotation speed change limit.

The jerk limit may be adjusted where the stick limit is used to keep the resulting friction force below the stick limit. The jerk is a change in acceleration. The wheels may spin or slip due to the jerk being too great. The driving stability of the vehicle can be improved by adjusting the jerk limit.

The lateral slip angle of the wheel may be limited to keep the resulting friction below the adhesion limit. In the case of too large a lateral slip angle, the vehicle may be under-steered and moved by the front axle. The curve stability of the vehicle can be improved by limiting the lateral slip angle.

The shift speed threshold may be adjusted with the adhesion limit used to keep the resulting friction below the adhesion limit. The shift speed threshold may be a threshold value of: at the threshold, a shift from one gear to the next is made. In the case of a low adhesion limit, the shift speed threshold can be lowered in order to shift into a higher gear already at a lower speed, as a result of which the torque at the driven wheels can be limited.

The method may be implemented, for example, in software or hardware or in a mixture of software and hardware, for example, in a controller.

The invention proposed here also proposes a control unit which is designed to carry out, control or carry out the steps of the variants of the method proposed here in a corresponding device.

The controller can be an electrical appliance having at least one computing unit for processing signals or data, at least one memory unit for storing signals or data, and at least one interface and/or communication interface for reading in or outputting data embedded in a communication protocol. The computation unit may be, for example, a signal processor, a so-called system ASIC, or a microcontroller for processing the sensor signal and outputting a data signal as a function of the sensor signal. For example, the memory cells may be flash, EPROM, or magnetic memory cells. The interface may be designed as a sensor interface for reading in sensor signals from the sensor and/or as an actuator interface for outputting data signals and/or control signals to the actuator. The communication interface can be designed for reading in or outputting data wirelessly and/or by wire. The interface may also be a software module that is co-located with other software modules, for example on a microcontroller.

A computer program product or a computer program having a program code which can be stored on a machine-readable carrier or memory medium, such as a semiconductor memory, a hard disk memory or an optical memory, and which is used to carry out, implement and/or manipulate the steps of the method according to one of the preceding embodiments, to put it into effect and/or to regulate it, in particular when the program product or program is executed on a computer or a device, is also advantageous.

It is pointed out that some of the possible features and advantages of the invention are described herein with respect to a number of different embodiments. Those skilled in the art realize that the features of the controller and the features of the method may be combined, adapted or substituted in a suitable manner in order to arrive at further embodiments of the present invention.

Drawings

Embodiments of the invention are described hereinafter with reference to the accompanying drawings, which are not to be construed as limiting the invention, nor is the specification read as limiting.

FIG. 1 shows a diagram of a vehicle having a controller according to one embodiment.

The figures are merely schematic and are not to scale. The same reference numbers in the figures denote the same or functionally similar features.

Detailed Description

FIG. 1 shows a diagram of a vehicle 100 having a controller 102, according to one embodiment. The controller 102 is connected to the ultrasonic sensor system 104 of the vehicle 100. The ultrasonic sensor system 104 provides road status information 106. The road state information 106 is determined by an evaluation of at least one noise level 108 sensed on the vehicle 100. The road status information 106 reflects whether the road in the area of the vehicle 100 is wet, or flooded.

If a road is wet, wet or submerged, it has a lower friction value than if the same road were dry. Thus, the wheel may transmit less friction to the road in wet, wet or flooded road conditions. It is not important here to consider "whether the longitudinal force is used for acceleration or deceleration or the lateral force is used for steering or lane keeping".

Here, in general, even in the case of dry roads, the longitudinal forces that can be transmitted are somewhat greater than the lateral forces.

In the control unit 102, the evaluation road state information 106 is evaluated in a determination device 110 and the adhesion limit 112 is determined individually for each wheel of the vehicle 100. The adhesion limit 112 is used by the influencing device 114 to influence the response behavior of the vehicle 100. In this case, influencing device 114 can intervene in the driving dynamics of vehicle 100 in order to keep the friction at the wheels below adhesion limit 112.

In the method proposed here, the vehicle behavior is influenced as a function of the water level on the roadway, measured with ultrasound.

The measurement of the road condition by means of the noise level 108 can be realized. The own vehicle 100 emits a noise level and this noise level 108 is measured by an ultrasonic sensor (USS), the greater the speed of the own vehicle, the greater the noise level.

Wetness on the roadway can be sensed by means of an ultrasonic sensor. Alternatively or additionally, the wetness information 116 may be received over a radio interface.

The driving behavior of the vehicle 100 is optimized by means of the wetness information 116 or the road state information 112.

Whether the road is wet or dry is measured using ultrasonic sensing devices and an estimate is made as to whether one of the wheels has reached the adhesion limit 112 based on vehicle speed, tire properties and forces acting on the wheels. Limiting the force applied to the wheel based on the measurements and estimates.

In one embodiment, in the event of moisture, the maximum permissible regeneration torque is reduced, so that negative effects on the vehicle stability are not feared. Preventing regeneration in the face of a aquaplaning hazard. Thereby improving the stability of the vehicle 100.

In one embodiment, the drag torque of the internal combustion engine is reduced in the case of wet roads and is completely compensated in the event of a risk of water slip. In this case, the sensible intervention is combined with information to the driver. This improves the stability. Furthermore, the braking torque at the rear wheels is reduced to a minimum value and the gear shift is inhibited to avoid giving (positive as well as negative) torque to the drive train. This also improves the stability of vehicle 100.

In one embodiment, the tire is prevented from slipping or sticking by means of a rotational speed variation limit. For this purpose, the rotational speed variation limit is selected such that the rotational speed can only be increased as quickly as would be possible if there was a friction lock and the lane was dry or wet. The speed change limit is therefore selected to be high in the case of dry roads and to be low in the case of wet roads. Thereby, the vehicle 100 can be accelerated more quickly.

In one embodiment, the maximum jerk limit is selected to be higher in case of dry roads than in case of wet roads. A large jerk or large change in torque may cause vehicle 100 to become unstable. With this limitation, the risk of the vehicle 100 becoming unstable in the case of wet roads is limited, while an optimal response behavior is ensured in the case of dry roads.

In one embodiment, the transmission is shifted into a higher gear earlier when accelerating on a wet road than when the road is dry. In contrast, the transmission is shifted later into the lower gear during braking. The gear-to-speed ratio g/v, which is derived from the selected gear g relative to the vehicle speed v, is selected to be higher in the case of wet roads than in the case of dry roads. Thereby, efficiency and vehicle stability are improved.

In one embodiment, the maximum lateral slip angle is limited by the steering controller. This means that a counter moment acting on the steering device is given in order to thereby reduce excessively strong cornering. This enables a narrower curve radius and improved stability.

The solution proposed here increases the energy efficiency and allows faster acceleration, whether wet or dry. Further, the vehicle 100 behaves more stably and more safely.

Finally it is pointed out that concepts such as "having", "comprising" and the like do not exclude other elements or steps, and that concepts such as "a" or "an" do not exclude a plurality. Reference signs in the claims shall not be construed as limiting.

Claims

1. Method for operating a vehicle (100), in which method road state information (106) representing a friction value of a road in the region of the vehicle (100) is read in from an ultrasonic 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 state information (106), wherein the response behavior of the vehicle (100) is influenced using the adhesion limit (112).

2. Method according to claim 1, in which method the adhesion limit (112) is also determined using the wheel support force of the wheel.

3. Method according to any one of the preceding claims, in which method the adherence limit (112) is also determined using tyre state information of the tyres of the wheel.

4. Method according to any one of the preceding claims, in which method the drag torque on the wheel is limited in order to keep the resulting friction force below the adhesion limit (112).

5. Method according to any one of the preceding claims, in which method the drive torque on the wheel is limited in order to keep the generated friction below the adhesion limit (112).

6. Method according to any one of the preceding claims, in which method the limit of the change in rotational speed of the wheel is adjusted in the case of the use of the adhesion limit (112) in order to keep the generated friction below the adhesion limit (112).

7. Method according to any one of the preceding claims, in which method a jerk limit is adjusted in the case of the use of the adhesion limit (112) in order to keep the generated friction force below the adhesion limit (112).

8. Method according to any one of the preceding claims, in which method the lateral slip angle of the wheel is limited in order to keep the generated friction below the adhesion limit (112).

9. Method according to any one of the preceding claims, in which method a gear shift speed threshold is adjusted with the adhesion limit (112) used in order to keep the generated friction below the adhesion limit (112).

10. A controller (102) configured for implementing, implementing and/or handling the method according to any of the preceding claims in a respective device.

11. Computer program product arranged for, implementing and/or handling a method according to any one of claims 1 to 9.

12. A machine-readable memory medium on which the computer program product of claim 11 is stored.