WO2024084140A1

WO2024084140A1 - Method and device for limiting a setpoint speed of an adaptive cruise control of an autonomous vehicle

Info

Publication number: WO2024084140A1
Application number: PCT/FR2023/051343
Authority: WO
Inventors: Luc VIVET
Original assignee: Stellantis Auto Sas
Priority date: 2022-10-20
Filing date: 2023-09-07
Publication date: 2024-04-25
Also published as: FR3141126A1

Abstract

The invention relates to a method and a device for limiting a setpoint speed of an adaptive cruise control of an autonomous vehicle, referred to as the ego vehicle, said ego vehicle nearing a target vehicle, said method comprising steps of: - receiving (201) the setpoint speed, an ego speed, and the speed of the target; - determining (202) an increased speed for the speed of the target; - if (203) the increased speed is lower than the setpoint speed and if the ego speed is lower than the setpoint speed: o determining (204) a comfortable speed, the comfortable speed being lower than the setpoint speed, the comfortable speed being higher than the speed of the target; o limiting (205) the setpoint speed by the comfortable speed.

Description

DESCRIPTION

TITLE: Method and device for limiting a set speed of an adaptive cruise control of an autonomous vehicle

The present invention claims the priority of French application 2210839 filed on 10/20/2022, the content of which (text, drawings and claims) is here incorporated by reference.

Technical field of the invention

[0001] The invention is in the field of autonomous vehicle driving assistance systems. In particular, the invention relates to a method and a device for limiting a set speed of an adaptive cruise control of an autonomous vehicle.

State of the art

[0002] The term “vehicle” means any type of vehicle such as a motor vehicle, a moped, a motorcycle, a storage robot in a warehouse, etc. “Autonomous driving” of an “autonomous vehicle” means any process capable of assisting the driving of the vehicle. The method may thus consist of partially or totally steering the vehicle or providing any type of assistance to a natural person driving the vehicle. The process thus covers all autonomous driving, from level 0 to level 5 in the OICA scale, for International Organization of Automobile Manufacturers.

[0003] The processes capable of assisting the driving of the vehicle are also called ADAS (from the English acronym “Advanced Driver Assistance Systems”), ADAS functions, ADAS systems or driving assistance systems. Among these ADAS systems, adaptive cruise control is known.

[0004] Adaptive cruise control is also known as ACC (from the English acronym “Auto Cruise Control”). This system automatically maintains a speed of the vehicle, called the ego vehicle, at a value set by an occupant or driver of the vehicle, a value known as the set speed, while respecting a safety distance with an object preceding the ego vehicle. For example, an object preceding the ego vehicle is a land vehicle, any type of obstacle, any disturbance... The object is upstream of the ego vehicle, on a possible trajectory of the ego vehicle. The safety distance is determined from an inter-vehicle time, Tiv, set by the driver and from a speed of the vehicle ego.

[0005] An ACC generally uses a camera installed at the top of a windshield of the vehicle and a radar installed in a front bumper of the vehicle in order to detect and identify objects in an environment. close to the vehicle. A vehicle equipped with an ACC is capable of detecting several objects in front of the ego vehicle, and is capable of determining data associated with these objects such as speed, position, characteristics typing the object, etc. An object is also called target object, or target vehicle, if this object is involved in the implementation of the ACC. [0006] In the absence of detection of a target vehicle, if the speed of the ego vehicle is lower than the set speed, the ACC will accelerate the ego vehicle until the speed of the vehicle ego vehicle reaches the target speed. Conventionally, the cruise control will generate an acceleration proportional to the difference between the set speed and the speed of the vehicle ego. Once the target speed is reached, the ACC maintains the speed of the ego vehicle at the set speed. The ego vehicle is said to accost a target vehicle, for example, when the target vehicle is overtaken by the ego vehicle, the ego vehicle traveling faster than the target vehicle, then when the speed of the ego vehicle is regulated at the speed of the target vehicle at a distance corresponding to the set inter-vehicle time.

[0007] For example, a docking situation is an ego vehicle and a target vehicle traveling at a speed lower than the set speed, the ego vehicle traveling faster than the target vehicle, the ego vehicle being at a time inter-vehicles greater than an inter-vehicle time set by an occupant of the vehicle ego. Current cruise control systems handle this situation poorly, especially when the ego vehicle overtakes the target vehicle (the ego vehicle begins to detect the target vehicle). In this case, the inter-vehicle time is very long. The inter-vehicle distance is greater than the safety distance. The cruise control will continue to accelerate the ego vehicle so that the ego vehicle reaches the set speed. Then, when the inter-vehicle distance becomes close to the safety distance, the regulator will brake (decelerate) the ego vehicle strongly enough to respect the inter-vehicle time set by the driver and regulate the speed of the ego vehicle at the speed of the target vehicle.

[0008] Document US 2016304092 discloses a method of assisting a driver in driving a vehicle.

Summary of the invention

[0009] An object of the present invention is to remedy the aforementioned problem, in particular to avoid accelerating too much and then braking the ego vehicle too much when it approaches a target vehicle.

[0010] For this purpose, a first aspect of the invention relates to a method of limiting a set speed of an adaptive speed regulator of an autonomous vehicle, called ego vehicle, said set speed being fixed by a occupant of said ego vehicle, said ego vehicle accosting a target vehicle, said method comprising steps of:

- Reception, via an input interface, of said set speed, of a speed of said ego vehicle, called ego speed, of a speed of said target vehicle, called speed of the target;

- Determination of a speed increased by said speed of the target, called increased speed, said increased speed being strictly greater than said speed of the target;

- If said increased speed is lower than said set speed and if said ego speed is lower than said set speed: o Determination of a comfort speed from said ego speed and said target speed, said comfort speed being lower than the set speed, said comfort speed being greater than said target speed; o Limitation of said set speed by said comfort speed, said adaptive speed regulator taking into account the limited set speed.

[0011] Thus, we are in a phase of docking a target vehicle by the vehicle ego. For this, thanks to the invention, the speed of the ego vehicle will become greater than the speed of the target vehicle to catch up with the target vehicle. However, the speed of the ego vehicle will remain lower than the set speed. The cruise control takes into account the limited set speed. Since the limited set speed is lower than the set speed, the difference between the limited set speed and the ego speed is smaller than the difference between the set speed and the vehicle ego. The cruise control will therefore accelerate less. When the vehicle ego approaches the target speed at a distance close to an intervehicle time set by an occupant of the vehicle, the difference between the target speed and the ego speed is smaller than when the cruise control does not take take into account the limited set speed. The regulator has less need to decelerate (brake) the ego vehicle so that the ego vehicle circulates behind the target vehicle at the speed of the target vehicle according to the inter-vehicle time set by the occupant. The ego vehicle accelerating less and braking less is perceived more comfortably by occupants of the ego vehicle. On the other hand, limiting variations in acceleration, the energy consumption to move the vehicle is lower.

[0012] Advantageously, the comfort speed is also determined from the increased speed.

[0013] Advantageously, said comfort speed is at least equal to the maximum between said ego speed and said increased speed.

[0014] Thus, the comfort speed remains at least significantly higher than the speed of the target vehicle while being lower than the set speed. If the ego speed is lower than the increased speed, the ego vehicle continues to accelerate to catch up with the target vehicle more quickly but less strongly than without the invention. If the ego speed is greater than or equal to the increased speed, the cruise control will no longer accelerate or decelerate the ego vehicle. It is said that the speed of the ego vehicle has reached a plateau, the acceleration is zero.

Advantageously, said increased speed is determined by the equation V _maJ = ^V dbie + AV, where Vmaj is said increased speed, Vdbie is said speed of the target, and AV is a predetermined speed.

[0016] Thus, the increased speed is easily configurable.

Advantageously, the comfort speed is at least equal to a predetermined minimum speed, said predetermined minimum speed being lower than said set speed. [0018] Thus, a minimum speed is imposed on the limited speed. This allows for greater response dynamics by vehicle ego actuators such as the engine. Indeed, the ego vehicle actuators are limited in response time. Thus, the vehicle ego adapts more quickly to the environment at low speed (speed below the minimum speed). At low speed the environment is more uncertain than at high speed. Indeed, at low speed, a vehicle is more able to change direction more quickly. At higher speeds, the determined comfort speed is greater than the minimum speed, so comfort is optimized.

[0019] A second aspect of the invention concerns a device comprising a memory associated with at least one processor configured to implement the method according to the first aspect of the invention.

[0020] The invention also relates to a vehicle comprising the device.

[0021] The invention also relates to a computer program comprising instructions which, when the program is executed by the device according to the second aspect of the invention, lead it to implement the method according to the first aspect of the invention.

Brief description of the figures

Other characteristics and advantages of the invention will emerge from the description of the non-limiting embodiments of the invention below, with reference to the appended figures, in which:

[0023] [Fig. 1] schematically illustrates a device, according to a particular embodiment of the present invention.

[0024] [Fig. 2] schematically illustrates a method for limiting a set speed of an adaptive cruise control of an autonomous vehicle, called ego vehicle, according to a particular embodiment of the present invention.

Detailed description of the invention

The invention is described below in its non-limiting application to the case of an autonomous motor vehicle traveling on a road or on a lane. Other applications such as a robot in a storage warehouse or a motorcycle on a country road are also possible.

[0026] Figure 1 represents an example of device 101 included in the vehicle, in a network (“cloud”) or in a server. This device 101 can be used as a centralized device in charge of at least certain steps of the method described below with reference to Figure 2. In one embodiment, it corresponds to an autonomous driving computer.

[0027] In the present invention, the device 101 is included in the vehicle.

This device 101 can take the form of a box comprising printed circuits, any type of computer or even a mobile telephone (“smartphone”). The device 101 comprises a RAM 102 for storing instructions for the implementation by a processor 103 of at least one step of the method as described above. The device also includes a mass memory 104 for storing data intended to be retained after implementation of the method.

The device 101 may also include a digital signal processor (DSP) 105. This DSP 105 receives data to format, demodulate and amplify this data in a manner known per se.

[0031] The device 101 also comprises an input interface 106 for receiving the data implemented by the method according to the invention and an output interface 107 for transmitting the data implemented by the method according to the invention .

[0032] For example, the input interface 106 can receive the following data: position or geographical location of the vehicle, speed and/or acceleration of the vehicle, set or predetermined positions/speeds/accelerations, engine speed, position and/or travel of the clutch, brake and/or acceleration pedal, detection of other vehicles or objects, position or geographical location of other vehicles or objects detected, speed and/or acceleration of other vehicles or objects detected, operating states operation of sensors, confidence index of data originating from or processed by sensors and/or devices similar to the device 101. For example, the sensors capable of providing data are: GPS associated or not with mapping, tachometers, accelerometers, RADAR, LIDAR, lasers, ultrasound, camera, etc.

[0033] In particular, the input interface can receive a set speed set by an occupant of the vehicle, a speed of the vehicle, a speed of a target vehicle, an increased speed of the target vehicle, at least one predetermined speed , ... For example, the output interface 107 can transmit data similar to the data received by the input interface 106. In particular, the output interface can transmit an increased speed, a comfort speed, at minus a predetermined speed, a limited set speed, etc.

Of course, when we talk about data of a quantity such as position, speed, acceleration, etc., we are talking about a value of the quantity. For example, when the input interface 106 receives a speed, a value of the speed is received, when the output interface 107 transmits a limited set speed, a value of this speed is transmitted.

[0035] [Fig. 2] schematically illustrates a method for limiting a set speed of an adaptive cruise control of an autonomous vehicle, called ego vehicle, according to a particular embodiment of the present invention. In this example, said set speed is set by an occupant of said ego vehicle. Adaptive cruise control is also called ACC, ACC function, or cruise control. Conventionally, an occupant of said vehicle activates an ACC function by an action on a man-machine interface. The occupant selects a set speed, for example 36 m/s (approximately 130 km/h, other values are possible), and selects an inter-vehicle time for example 2 seconds (other values are possible).

[0036] In this example, said ego vehicle approaches a target vehicle. At a given moment, the speed of the ego vehicle, called ego speed, must be greater than the speed of said target vehicle, called target speed, so that the ego vehicle catches up with the target vehicle. With the ACC activated, the ego speed will not become significantly higher (several km/h) than the set speed. If there is docking, the target speed is lower than the set speed. For example, a target speed can be 25 m/s (90 km/h, other values are possible).

When the driver activates ACC, it is not necessary for the ego speed to be higher than the target speed. This is for example the case, during a motorway junction, the ego vehicle traveling on an insertion lane at 16 m/s (around 58 km/h, other values are possible). The ego vehicle will therefore accelerate and enter the right lane of the highway. In this example, the target vehicle is a truck traveling at 25 m/s on the right lane of the highway, in front of the vehicle at a distance of approximately 100 m, i.e. approximately 4 seconds of inter-vehicle time for a speed of 25 m/s.

[0037] Step 201, Rx, is a step of Receiving (201), via an input interface (106), of said set speed, of a speed of said ego vehicle, called ego speed, of a speed of said target vehicle, called speed of the target. In this step, the process regularly receives values of the different speeds in order to be able to regularly determine the limitation of the set speed. By regularly, we mean either a periodic reception as a multiple of milliseconds, such as 1 ms, 5 ms, 20 ms, 100 ms, 1000 ms, ... other values are possible, or an aperiodic reception (for example a at least once another multiple of milliseconds).

Step 202, DetVmaj, is a step of determining a speed increased by said speed of the target, called increased speed, said increased speed being strictly greater than said speed of the target. This increased speed allows a limited set speed, determined below, to be higher than the target speed. Thus the ego vehicle approaches the target vehicle more quickly. There are multiple ways to determine the increased speed, for example it can depend on the difference between the set speed and the target speed. The more the increased speed is greater than the speed of the target, the more dynamic the speed regulation is, and the less significant the advantages of the invention.

[0039] In a preferred operating mode, said increased speed is determined by the equation V _maj = V _target + AK, where Vmaj is said increased speed, Vdbie is said speed of the target, and AV is a predetermined speed. Very simply, we increase the speed of the target by an offset or bias. For example, said predetermined speed, or offset, is between 10 km/h and 50 km/h. Taking a predetermined speed value close to 20 km/h gives a good compromise between dynamics (rapid access to the target) and comfort (minimization of acceleration and deceleration during docking). Other values are possible and may depend on conditions in the environment close to the vehicle (speed limit, traffic density, etc.).

Step 203, Test, is a test step if said increased speed is lower than said set speed and if said ego speed is lower than said set speed. If so, we move on to step 204.

[0041] Step 204, detVconf, is a step of determining a comfort speed from said ego speed and said speed of the target, said comfort speed being lower than the set speed, said speed of comfort being greater than said target speed. According to test 203, we arrive at this stage when the ego speed and, also, the speed of the target are lower than the set speed. There are several ways to determine a comfort speed such that this comfort speed is greater than the target speed and less than the set speed.

[0042] Advantageously, the comfort speed is also determined from the increased speed. Also taking into account the increased speed in determining the comfort speed makes it possible to make the effects of the invention more visible. Indeed, if the increased speed is close, by a few km/h, to the set speed, the set speed is only slightly limited.

Advantageously, said comfort speed is at least equal to the maximum between said ego speed and said increased speed. If at the start of ACC activation, the ego speed is lower than the target speed, the comfort speed is equal to the increased speed. The ego vehicle accelerates as long as the ego speed is lower than the increased speed. In this situation, the vehicle ego accelerates less strongly than speed control in the absence of limitation by the comfort speed. Once the ego speed is equal to the increased speed, the comfort speed remains equal to the increased speed, acceleration of the ego vehicle is zero for a certain time. This certain time depends on an inter-vehicle distance between the ego vehicle and the target vehicle. During this time, the speed of the ego vehicle is said to be on a plateau: During the entire docking phase, the speed of the ego vehicle reached a maximum before decreasing again to converge towards the speed of the target , the speed is constant during this certain time.

If at the start of activation of the ACC, the ego speed is greater than or equal to the speed of the target, the comfort speed is maintained at the ego speed. The comfort speed remains equal to the ego speed, an acceleration of the ego vehicle is zero for a certain time. This certain time depends on an inter-vehicle distance between the ego vehicle and the target vehicle. During this time, the speed of the ego vehicle is said to be on a plateau: During the entire docking phase, the speed of the ego vehicle reached a maximum before decreasing again to converge towards the speed of the target , the speed is constant during this certain time. [0045] Advantageously, the comfort speed is at least equal to a predetermined minimum speed, said predetermined minimum speed being less than said set speed

[0046] Thus, when the ego vehicle and the target vehicle are initially traveling at low speed, a speed significantly lower than the set speed, we wish to have greater accelerations because the actuators of the ego vehicle (motor, for example ) are limited in response time. At low speed, you quickly adapt to the environment. At low speed the environment is more uncertain than at high speed. Indeed, at low speed, a vehicle is more able to change direction more quickly. At higher speeds, the determined comfort speed is greater than the minimum speed, so comfort is optimized.

For example, the predetermined minimum speed is between 30 km/h and 70 km/h. Other values are possible. In a preferred operating mode the minimum speed is equal to 50 km/h.

[0047] Step 205, Vlim, is a step of Limitation of said setpoint speed by said comfort speed, said adaptive speed regulator taking into account the limited setpoint speed. In the situations described above, compared to state-of-the-art adaptive cruise control, the ego vehicle accelerated less strongly and decelerated less strongly. An occupant of the ego vehicle therefore feels less variations in acceleration, the vehicle is then felt more comfortably.

The present invention is not limited to the embodiments described above by way of examples: it extends to other variants.

[0049] Thus, an embodiment has been described above in which the invention was described in the context of the application to adaptive speed regulation. The invention is not limited to such an application and can be implemented for example for methods/devices for keeping in the lane or for making decisions for changing lanes, or other ADAS systems which use regulation. speed.

An embodiment has also been described above in which a target vehicle is detected. The invention is not limited to such an application and can be implemented for example when more than one target vehicle is detected.

[0051] Equations and calculations have also been detailed. The invention is not limited to the form of these equations and calculations, and extends to any type of other mathematically equivalent form.

[0052] Furthermore, the steps described with reference to Figure 2 were in a precise order. A different order is also possible. For example, step 204 can be carried out before or simultaneously with step 202.

Claims

1. Method for limiting a set speed of an adaptive cruise control of an autonomous vehicle, called ego vehicle, said set speed being set by an occupant of said ego vehicle, said ego vehicle approaching a target vehicle, said method comprising steps of:

- Reception (201), by an input interface (106), of said set speed, of a speed of said ego vehicle, called ego speed, of a speed of said target vehicle, called speed of the target;

- Determination (202) of a speed increased by said speed of the target, called increased speed, said increased speed being strictly greater than said speed of the target;

- If (203) said increased speed is lower than said set speed and if said ego speed is lower than said set speed: o Determination (204) of a comfort speed from said ego speed and said speed of the target, said comfort speed being lower than the set speed, said comfort speed being greater than said speed of the target; o Limitation (205) of said set speed by said comfort speed, said adaptive speed regulator taking into account the limited set speed.

2. Method according to claim 1, wherein said comfort speed is determined (204) further from the increased speed.

3. Method according to the preceding claim, wherein said comfort speed is at least equal to the maximum between said ego speed and said increased speed.

4. Method according to one of the preceding claims, in which said increased speed is determined (202) by the equation V _maj = V _target + AK, where Vmaj is said increased speed, Vdbie is said speed of the target, and AV is a predetermined speed.

5. Method according to one of the preceding claims, wherein said comfort speed is at least equal to a predetermined minimum speed, said predetermined minimum speed being lower than said set speed.

6. Device (101) comprising an input interface (106), a memory (102) associated with at least one processor (103) configured to implement the method according to one of the preceding claims.

7. Vehicle comprising the device according to the preceding claim.

8. Computer program comprising instructions which, when the program is executed by the device (101), lead it to implement the method according to one of claims 1 to 5.