Method for controlling a driver assistance system in a road vehicle and device for performing said method and vehicle

Abstract

The invention relates to a method for controlling a driver assistance system in a road vehicle (22) which has an electronically controllable drive motor (24) and an electronically controllable service brake system with wheel brake cylinders (30, 32, 34, 36) actuated by a pressure medium, and for which the driver assistance system has camera-based vehicle, pedestrian and traffic sign recognition as well as a cruise control function and an emergency braking function, wherein when the road vehicle (22) approaches a recognised bus or tram stop (2), a control unit (26) of the driver assistance system carries out at least one further measure to avoid a collision with a pedestrian (14.1, 14.2, 14.3) in addition to generating and outputting a warning signal to the driver of the road vehicle (22). According to the invention, as an additional measure, the wheel brake cylinders (30, 32, 34, 36) of the service brake system of the road vehicle (22) are pre-filled with a predetermined fluid pressure in preparation for a possible emergency braking before reaching the bus or tram stop (2). The invention further relates to a device (40) for performing said method.

Description

[0001] Method for controlling a driver assistance system in a road vehicle and device for carrying out this method and vehicle

[0002] The invention relates to a method for controlling a driver assistance system in a road vehicle, which has an electronically controllable drive motor and an electronically controllable service brake system with fluid-operated wheel brake cylinders, and whose driver assistance system has camera-based vehicle, pedestrian, and traffic sign recognition, as well as a cruise control function and an emergency braking function. When the road vehicle approaches a detected bus or tram stop, a control unit of the driver assistance system, in addition to generating and outputting a warning signal to the driver of the road vehicle, carries out at least one further measure to avoid a collision with a pedestrian. Furthermore, the invention relates to a device on the road vehicle for carrying out this method.

[0003] On public roads, there are dangerous spots such as intersections, road junctions, and the entrances and exits to busy parking lots, such as those at supermarkets, businesses, and tourist destinations, where, based on experience, collisions between vehicles occur relatively frequently. In contrast, city and regional bus stops and tram stops, which are usually located at the side of the road, represent dangerous spots where collisions between vehicles and pedestrians can occur. This is because pedestrians at stops often cross the adjacent road using the shortest route in order to reach the public transport system, such as a bus or tram, in time, or to reach their destination, such as their home, workplace, or a supermarket, as quickly as possible after leaving the public transport system.There is therefore a general interest in increasing road safety at bus and tram stops by avoiding collisions between road vehicles passing the stops and pedestrians crossing the street in the vicinity of such a stop. Against this background, DE 102015 225 900 B3 discloses a method for camera-based traffic sign recognition in a motor vehicle. A traffic sign sensed and subsequently recognized by a camera is considered relevant for the vehicle if the relative speed at which the vehicle is moving toward the traffic sign matches the vehicle's driving speed within a specified tolerance.

[0004] US 2022 / 0 234 578 A1 describes an emergency braking assistant for a road vehicle that determines a potential collision point between the vehicle and a detected pedestrian based on the current positions and speeds of both road users as the intersection point of the determined trajectories. Emergency braking of the vehicle is triggered when approaching the collision point if both road users are expected to reach it at approximately the same time.

[0005] From DE 10 2011 018 157 A1, a driver assistance system of a road vehicle is known with which a stop for buses or trams located at the roadside is detected on the basis of camera-based information and image data and, depending on the detected traffic situation, such as a bus standing at the stop, an acoustic and / or optical warning signal is issued to the driver of the vehicle.

[0006] The invention is based on the object of improving known methods for controlling a driver assistance system in a road vehicle in such a way that traffic safety at bus and tram stops is further increased. Furthermore, a device on a road vehicle is to be presented with which such an improved method can be implemented.

[0007] This object is achieved by a method or device having the features of the respective independent claims. Advantageous further developments are defined in the dependent claims.

[0008] Accordingly, the invention initially relates to a method for controlling a driver assistance system in a road vehicle, which has an electronically controllable drive motor and an electronically controllable service brake system with pressure-medium actuated wheel brake cylinders, and whose driver assistance system has a camera-based vehicle, pedestrian and traffic sign recognition as well as a cruise control function and an emergency braking function, wherein when the road vehicle approaches a recognized bus or tram stop, a control unit of the driver assistance system carries out at least one further measure to avoid a collision with a pedestrian in addition to generating and outputting a warning signal to the driver of the road vehicle.

[0009] To solve the problem, this method provides for the wheel brake cylinders of the service brake system of the road vehicle to be pre-filled with a predetermined fluid pressure before reaching the bus or tram stop in preparation for a possible emergency braking.

[0010] By pre-filling the wheel brake cylinders, for example, with compressed air or brake fluid, the brake pad carriers of the service brake system are pressed against the respective brake discs or drums with the brake pads, thus eliminating any normal free play without noticeably slowing the road vehicle. This means that the wheel brakes of the road vehicle respond immediately when the brakes are applied, especially during emergency braking, so that the road vehicle decelerates more quickly than usual and comes to a stop sooner. This makes it more likely that a collision with a pedestrian can be avoided or at least achieved at a lower impact speed.

[0011] It is therefore intended that the camera-based detection of a bus or tram stop, without the need for such a public transport vehicle to be present at the stop, as well as the pre-filling of the wheel brake cylinders of the road vehicle's service brake system, will take place automatically. The wheel brake cylinders will always be pre-filled with fluid before the stop is reached, regardless of the road vehicle driver's subsequent braking decisions. The road vehicle can then also be decelerated automatically, i.e., without the driver having to manually operate the brake pedal.After braking, which can be initiated by the driver pressing the brake pedal or automatically, the wheel brake cylinders are depressurized, releasing the brake pad carriers (the brake blocks in disc brakes and the brake shoes in drum brakes) from the wheel-mounted brake elements (the brake discs in disc brakes and the brake drums in drum brakes) and separating them. In disc brake systems, this is achieved, for example, by a slight lateral runout of the brake discs and by a restoring force of the elastically deformed piston seals in the bores of the brake calipers, and in drum brake systems, by return springs between the brake shoes.

[0012] A further increase in road safety can be achieved by reducing the speed of the road vehicle, as this significantly shortens the braking distance when the brakes are applied, especially in an emergency. To this end, a further development of the method provides for the road vehicle to be automatically braked if its speed exceeds a safe speed appropriate to the detected traffic situation at the stop and the road vehicle's brake pedal is not depressed. When the brake pedal is depressed, responsibility for avoiding a collision is transferred from the driver assistance system to the driver.

[0013] To assess the traffic situation at the stop, a distinction can be made between four situations: a first situation: “stop without a bus or tram in front of it”, a second situation: “stop with a bus or tram in front of it with its hazard lights off”, a third situation: “stop with a bus or tram in front with its hazard lights on”, and a fourth situation: “stop with a bus or tram in front and its right-hand direction indicators flashing”.

[0014] In countries where traffic drives on the left, such as Japan or the United Kingdom, the fourth situation would be worded more appropriately: "A bus or tram stop with a bus or tram in front and the left turn indicators flashing." The fourth situation is also classified as a situation where, despite the hazard lights not being activated but the bus or tram being stationary, it can be assumed that the stationary bus or tram poses a particular hazard to pedestrians and therefore requires special attention.

[0015] In addition, the safety speed can be set depending on whether the stop is located within or outside a built-up area. The safety speed is set lower for a stop within a built-up area than for a stop outside a built-up area.

[0016] Accordingly, it may be provided that when approaching a stop without a bus or tram stationed there, the road vehicle is slowed down to a safety speed of 30 km / h within a built-up area and to a safety speed of 50 km / h outside a built-up area.

[0017] It may also be provided that, when approaching a stop containing a bus or tram that is stationary there with its hazard warning lights switched off, the road vehicle is slowed down to a safety speed of 15 km / h within a built-up area and to a limit speed of 25 km / h outside a built-up area.

[0018] When a means of public transport, such as a bus or tram, is stopped in front of a stop, special caution is required, as pedestrians may already be on the road behind the means of public transport in the direction of view and may suddenly step out of its shadow.

[0019] To take this into account, it can be provided that the road vehicle is decelerated to a safety speed of 7 km / h or walking pace when approaching a stop with a bus or tram parked there with its hazard warning lights activated, both within and outside of a built-up area. According to another embodiment of the method, it can be provided that the aforementioned warning signal is only generated and emitted if the road vehicle is traveling faster than a specified safety speed or walking pace. This safety speed or walking pace can be, for example, 7 km / h.

[0020] In order to avoid premature wear of the brake pads and heat-related damage to the wheel brakes, it may also be provided that the wheel brake cylinders of the service brake system are depressurised after passing the stop, provided that the road vehicle is no longer automatically decelerating, the brake pedal of the road vehicle is not actuated and no other function requires the wheel brake cylinders to be pre-filled with a pressurised fluid.

[0021] Finally, the method can provide for the road vehicle to be braked automatically and with full braking force to a standstill if, after pre-filling the wheel brake cylinders, the driver assistance system detects a person stepping out in front of the bus or tram in the forward direction of travel.

[0022] As already mentioned at the beginning, the invention also relates to a device on a road vehicle with which the described method can be carried out. This device has a control unit of a driver assistance system, which is signal-connected to a camera arranged on the front of the vehicle. Furthermore, this control unit is connected via a data line to a control unit of a service brake system of the road vehicle. The control unit of the service brake system is connected via control lines to electromagnetic switching valves, through which, when opened, a fluid pressure medium can be directed into the wheel brake cylinders of the service brakes of the road vehicle.The control unit of the driver assistance system is constructed and configured such that, upon camera-assisted detection of a bus or tram stop visible ahead of the road vehicle, it sends relevant information to the control unit of the service brake system. The control unit of the service brake system is constructed and configured such that, upon receipt of such information, it opens the switching valves for pre-filling the wheel brake cylinders with the pressure fluid and then closes them again. The invention further relates to a vehicle equipped with a device according to the invention.

[0023] The invention will be explained in more detail below with reference to an embodiment shown in the accompanying drawing.

[0024] Fig. 1 shows a bus stop at the roadside in a schematic representation, Fig. 2 shows the bus stop according to Fig. 1 with a bus standing in front of it with its hazard warning lights switched off,

[0025] Fig. 3 the bus stop according to Fig. 1 with a bus standing in front of it with its hazard warning lights switched on, and

[0026] Fig. 4 is a plan view of a bus stop on a street with a bus parked there and a road vehicle approaching the bus stop.

[0027] The bus stop 2 depicted in Fig. 1 is located on a footpath 5 directly at the curb 6 of a road 4. The stop 2 comprises a paved surface 8, a waiting shelter 10, and a stop traffic sign 12 in accordance with German traffic sign VZ 224. For example, at stop 2, three people are standing: a man 14.1, a woman 14.2, and a child 14.3. The stop 2 is depicted approximately as it would be perceived by a driver of a road vehicle 22 upon approaching.

[0028] Fig. 2 shows the same stop 2 with a bus 16 parked in front of it, whose lower hazard warning lights 18 and upper hazard warning lights 20 are off. Fig. 3 shows a similar traffic situation with the bus 16 parked in front of stop 2, but on this bus 16, the hazard warning lights 18, 20 are clearly switched on. The hazard warning lights 18, 20 can also be used as right turn indicators 18a, 20a or left turn indicators 18b, 20b, if they only flash on the respective side of the vehicle.

[0029] Fig. 4 shows the road vehicle 22 designed as a passenger car, which has a device 40 described below for carrying out the method according to the invention. Fig. 4 shows a situation in which the road vehicle 22 has approached the stop 2 so closely that it can be autonomously detected by a driver assistance system of the road vehicle 22 using a camera 28 arranged on the front of the vehicle. The detection area 29 of the camera 28 relevant for detection is illustrated by two dotted lines. This detection of stop 2 occurs, for example, based on road construction and / or stop construction features and / or based on the stop traffic sign 12 erected at stop 2.

[0030] The driver assistance system of the road vehicle 22 is a component of the device 40 for carrying out the method according to the invention, which is embodied on the road vehicle 22. The driver assistance system has suitable software stored in a control unit 26 of the driver assistance system. This control unit 26 of the driver assistance system is signal-connected to the aforementioned camera 28. The control unit 26 of the driver assistance system is also connected via a data line 44 to a control unit 38 of a service brake system of the road vehicle 22.

[0031] The control unit 38 of the service brake system is used to control the braking application of the service brakes of the road vehicle 22 and, for this purpose, reacts in a known manner during normal driving operation to a sensor-detected manual actuation of a brake pedal of the road vehicle 22. However, the control unit 38 of the service brake system can, under command from other control units of the road vehicle 22, also control braking application, if necessary, until the vehicle comes to a standstill, for example based on information from a cruise control function and / or a distance control function. These functions are stored, for example, in the control unit 26 of the driver assistance system. When braking is required, the control unit 38 of the service brake system actuates electromagnetic switching valves (not shown but known per se), through which a fluid or gaseous pressure medium can be conducted to the wheel brake cylinders 30, 32, 34, 36 of the road vehicle 22.

[0032] The road vehicle 22 further comprises an electronically controllable drive motor 24, which serves for its propulsion, but can also indirectly, with the aid of a compressor or another fluid pump, place a fluid under increased pressure for actuating the service brakes.

[0033] Alternatively, in vehicles with compressed air-operated brakes, the pressure is fed from a pressure reservoir to the service brakes. The appropriate pressure is generated at the service brakes via controllable solenoid valves. Compressed air-operated service brakes are primarily installed on commercial vehicles, especially trucks and their associated trailers.

[0034] The control unit 26 of the driver assistance system is constructed and configured such that, after camera-assisted detection of a stop 2 visible in front of the road vehicle 22, it can send relevant information to the control unit 38 of the service brake system. Furthermore, the control unit 38 of the service brake system is constructed and configured such that, upon receiving such information, it can send control signals to open the aforementioned solenoid valves in order to partially fill wheel brake cylinders 30, 32, 34, 36 of the service brakes. Once this pre-filling process is complete, the control unit 38 of the service brake system can send control signals to close the solenoid valves.

[0035] The method claimed here therefore uses the control unit 26 of the driver assistance system. This uses a camera-based detection function to detect vehicles, pedestrians, and traffic signs. Furthermore, the driver assistance system uses a cruise control function and an emergency braking function if necessary. The aforementioned functions of the driver assistance system are implemented in the control unit 26 of the driver assistance system using appropriate computer software, which evaluates data from suitable sensors and generates and sends control signals to actuators of the road vehicle 22.

[0036] When approaching a detected bus stop 2, in addition to issuing a warning signal to the driver, the wheel brake cylinders 30, 32, 34, 36 of the service brake system of the road vehicle 22 are prefilled with the aforementioned fluid in preparation for a possible emergency braking. This ensures that the wheel brakes respond immediately in an emergency braking situation and the braking distance is shortened, thus increasing the probability of preventing a collision with a person 14.3 (see Fig. 4). The location of the bus stop 2 can also be detected using a navigation system in conjunction with a digital road map on which the bus stop 2 is entered. However, a traffic sign recognition function of the driver assistance system is preferably used, by means of which a bus stop traffic sign 12 can be identified, since this procedure records the current traffic situation in a timely and situation-specific manner.In order to further increase traffic safety at stops 2, it is additionally provided that the road vehicle is automatically braked if the driving speed of the road vehicle exceeds a safety speed appropriate to the detected traffic situation at stop 2 and the brake pedal of the road vehicle 22 is not actuated.

[0037] For this purpose, the current traffic situation at the stop can be differentiated between a first situation “stop without a bus or tram in front”, a second situation “stop with a bus or tram in front with the hazard warning lights off”, a third situation “stop with a bus or tram in front with the hazard warning lights on”, and a fourth situation “stop with a bus or tram in front and the right direction indicators flashing”.

[0038] Likewise, the safety speed can be set depending on whether stop 2 is located within or outside a built-up area. The safety speed for stop 2 located within a built-up area is usually lower than for stop 2 located outside a built-up area.

[0039] In an exemplary embodiment, the function for automatically braking the road vehicle 22 can provide that the road vehicle 22 is braked to a safety speed of 30 km / h within a built-up area and to a safety speed of 50 km / h outside a built-up area when approaching a stop 2 without a bus 16 in front of it (traffic situation according to Fig. 1 ).

[0040] Furthermore, when approaching a stop 2 with a bus 16 parked in front of it with its hazard warning lights 18, 20 off (traffic situation according to Fig. 2), the road vehicle 22 is decelerated to a safety speed of 15 km / h within a built-up area and to a speed limit of 25 km / h outside a built-up area. Finally, when approaching a stop 2 with a bus 16 parked in front of it with its hazard warning lights 18, 20 on or its right-hand direction indicators 18a, 20a flashing (traffic situation according to Fig. 3), the road vehicle 22 is decelerated to a safety speed of 7 km / h (walking speed) both within and outside a built-up area. In states with left-hand traffic, this would occur if the direction indicators 18b, 20b on the left side of the vehicle were flashing while the bus 16 was parked.

[0041] List of reference symbols (part of the description)

[0042] stop, bus stop

[0043] Street

[0044] Footpath

[0045] roadside

[0046] Floor of the stop

[0047] waiting room

[0048] Stop traffic sign .1 person, man .2 persons, woman .3 persons, child

[0049] bus

[0050] Upper hazard warning lights on the bus a Lower right direction indicator b Lower left direction indicator

[0051] Lower hazard warning lights on the bus a Right upper direction indicator b Left upper direction indicator

[0052] road vehicle

[0053] drive motor

[0054] Driver assistance system control unit

[0055] camera

[0056] Camera detection range

[0057] Wheel brake cylinder of the service brake system, front right

[0058] Wheel brake cylinder of the service brake system, front left

[0059] Wheel brake cylinder of the service brake system, rear right

[0060] Wheel brake cylinder of the service brake system, rear left Service brake system control unit

[0061] Device on the road vehicle for carrying out the procedure

Claims

Patent claims 1. A method for controlling a driver assistance system in a road vehicle (22), which has an electronically controllable drive motor (24) and an electronically controllable service brake system with pressure-medium-actuated wheel brake cylinders (30, 32, 34, 36), and whose driver assistance system has camera-based vehicle, pedestrian and traffic sign recognition as well as a cruise control function and an emergency braking function, wherein when the road vehicle (22) approaches a recognized bus or tram stop (2), a control unit (26) of the driver assistance system, in addition to generating and outputting a warning signal to the driver of the road vehicle (22), initiates at least one further measure to avoid a collision with a pedestrian (14.1, 14.2, 14.3).3), characterized in that the wheel brake cylinders (30, 32, 34, 36) of the service brake system of the road vehicle (22) are pre-filled with a predetermined pressure in preparation for a possible emergency braking before reaching the bus or tram stop (2).

2. Method according to claim 1, characterized in that the road vehicle (22) is automatically braked if its driving speed exceeds a safety speed appropriate to the detected traffic situation at the stop (2) and the brake pedal of the road vehicle (22) is not actuated.

3. Method according to claim 2, characterized in that when assessing the traffic situation at the stop (2) a distinction is made between a first situation "stop (2) without a bus (16) or tram in front of it", a second situation "stop (2) with a bus (16) or tram in front of it with the hazard warning lights (18, 20) switched off", a third situation "stop with a bus or tram in front of it with the hazard warning lights switched on", and a fourth situation "stop with a bus or tram in front of it and the right direction indicators (18a, 20a) flashing".

4. Method according to claim 2 or 3, characterized in that the respective safety speed is additionally dependent on the location of the stop (2) within or outside a built-up area, wherein the safety speed is set lower for a stop (2) located within a built-up area than for the safety speed for a stop located outside a built-up area (2).

5. Method according to one of claims 2 to 4, characterized in that the road vehicle (22) is braked to a safety speed of 30 km / h within a built-up area and to a safety speed of 50 km / h outside a built-up area when approaching a stop (2) without a bus (16) or tram stationed there.

6. Method according to one of claims 2 to 4, characterized in that the road vehicle (22) is braked to a safety speed of 15 km / h within a built-up area and to a limit speed of 25 km / h outside a built-up area when approaching a stop (2) with a bus (16) or tram stationed there with its hazard warning lights (18, 20) switched off.

7. Method according to one of claims 2 to 4, characterized in that the road vehicle (22) is braked to a safety speed of 7 km / h or walking speed when approaching a stop (2) with a bus (16) or tram stationed there with its hazard warning lights (18, 20) switched on, inside and outside a built-up area.

8. Method according to one of the preceding claims, characterized in that the warning signal is only generated and output when the road vehicle (22) travels faster than a predetermined safety speed or walking speed.

9. Method according to one of the preceding claims, characterized in that the wheel brake cylinders (30, 32, 34, 36) of the service brake system are depressurized after passing the stop (2), provided that there is no longer any automatic braking of the road vehicle (22), the brake pedal of the road vehicle (22) is not actuated, and no other function requires the pre-filling of the wheel brake cylinders (30, 32, 34, 36) with the pressure medium.

10. Method according to one of the preceding claims, characterized in that the road vehicle (22) is braked automatically and with full braking force to a standstill if, after pre-filling of the wheel brake cylinders (30, 32, 34, 36), the driver assistance system detects a person (14.3) emerging in the forward direction of travel in front of the bus (16) or in front of the tram.

11. Device (40) on a road vehicle (22) for carrying out the method according to one of the method claims, characterized in that it has a control unit (26) of a driver assistance system, which is signal-connected to a camera (28) arranged on the front of the vehicle, that the control unit (26) of the driver assistance system is connected via a data line (44) to a control unit (38) of a service brake system of the road vehicle (22), that the control unit (38) of the service brake system is connected via control lines to electromagnetic switching valves, via which, in their open state, wheel brake cylinders (30, 32, 34, 36) on the service brakes of the road vehicle (22) can be filled with a fluid or gaseous pressure medium, that the control unit (26) of the driver assistance system is also constructed and configured in such a way thatthat after a camera-assisted detection of a stop (2) for a bus (16) or a tram visible in front of the road vehicle (22), it sends relevant information to the control unit (38) of the service brake system, and that the control unit (38) of the service brake system is further constructed and arranged such that, after receiving such information, it opens the switching valves for pre-filling the wheel brake cylinders (30, 32, 34, 36) with the pressure medium and then closes them again.

12. Vehicle with a service brake system, characterized in that the vehicle (22) is equipped with a device according to claim 11.

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