ADJUSTING THE LONGITUDINAL MOTION CONTROL OF A HOST MOTOR VEHICLE BASED ON THE ESTIMATION OF THE TRAVEL TRAJECTORY OF A LEADING MOTOR VEHICLE

Abstract

An automotive adaptive cruise control system for a host motor vehicle configured to operate in at least two different operating modes comprising at least a first operating mode in which a current speed of the host motor vehicle is controlled to maintain a cruise speed, and a second operating mode, in which the current speed of the host motor vehicle is controlled to maintain a cruise distance from a leading motor vehicle. In the second operating mode, the automotive adaptive cruise control system is further configured to estimate the travel trajectory of the motor vehicle relative to that of a leading motor vehicle, and when the leading motor vehicle is estimated to be departing from the travel trajectory of the host motor vehicle, to adjust one or more of the control parameters on based of which the automotive adaptive cruise control system operates in the second operating mode.

Claims

1.-8. (canceled)

9. An automotive adaptive cruise control (ACC) system for a host motor vehicle (B) configured to operate in at least two different operating modes configured to operate based on one or more control parameters, and comprising: a first operating mode, in which a current speed of the host motor vehicle (B) is controlled to maintain a cruise speed, and a second operating mode, in which the current speed of the host motor vehicle (B) is controlled to maintain a cruise distance from a leading motor vehicle (A); the operating modes are configured to operate based on one or more control parameters including one or more of the cruise speed, the cruise distance and the acceleration/deceleration profile to be implemented by the host motor vehicle (B) to maintain the cruise speed and distance; wherein the second operating mode, the automotive adaptive cruise control (ACC) system is further configured to: estimate a travel trajectory of the leading motor vehicle (A) relative to a travel trajectory of the host motor vehicle (B), determine whether the leading motor vehicle (A) is departing from the travel trajectory of the host motor vehicle (B) based on the estimated travel trajectory of the leading motor vehicle (A) relative to the travel trajectory of the host motor vehicle (B) and on a curvature of the road travelled by the leading and host motor vehicles (A, B), and when it is determined that the leading motor vehicle (A) is departing from the travel trajectory of the host motor vehicle (B), modify one or more of the control parameters based on which the automotive adaptive cruise control (ACC) operates in the second operating mode;

10. The automotive adaptive cruise control (ACC) system of claim 9, further configured to: modify one or more of the control parameters based on which the automotive adaptive cruise control (ACC) system operates in the second operating mode also based on the type of road on which the leading and host motor vehicles (A, B) are travelling, so as to differentiate the behaviour of the automotive adaptive cruise control (ACC) system in the second operating mode differentiating among urban, suburban, and highway scenarios.

11. The automotive adaptive cruise control (ACC) system of claim 9, further configured to: estimate road adherence of the host motor vehicle (B), and modify one or more of the control parameters based on which the automotive adaptive cruise control (ACC) system operates in the second operating mode based also on the estimated road adherence of the host motor vehicle (B).

12. The automotive adaptive cruise control system (ACC) system of claim 9, further configured to estimate the trajectory of the leading motor vehicle (A) relative to that of the host motor vehicle (B) based on the following variables: a geometry of the road travelled by the host and leading vehicles (A, B), which is defined by a road curvature, and optionally, if available, also by other road-related information such as a road slope, a number of road lanes, and road junctions and intersections; distances of the host motor vehicle (B) and of the leading motor vehicle (A) from a lane centre, lateral speed of the leading motor vehicle (A), and activation of a direction indicator of the leading motor vehicle (A).

13. The automotive adaptive cruise control (ACC) system of claim 9, further configured to modify either or both the cruise distance and the acceleration profile of the host motor vehicle (B) to maintain the cruise distance when it is determined that the leading motor vehicle (A) is departing from the travel trajectory of the host motor vehicle (B).

14. The automotive adaptive cruise control (ACC) system of claim 13, further configured to reduce the cruise distance when it is determined that the leading motor vehicle (A) is departing from the travel trajectory of the host motor vehicle (B).

15. The automotive adaptive cruise control (ACC) system of claim 13, further configured to modify the acceleration profile of the host motor vehicle (B) to result in the cruise speed of the host motor vehicle (B) being quickly restored after the leading motor vehicle (A) has departed from the travel trajectory of the host motor vehicle (B).

16. A motor vehicle (B) comprising the automotive adaptive cruise control (ACC) system of claim 9.

17. A software loadable into an automotive electronic control unit (ECU) and designed to cause, when executed, the automotive electronic control unit to implement the automotive adaptive cruise control (ACC) system of claim 9.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIGS. 1 and 2 show functional block diagrams of operations carried out by an automotive electronic control unit to implement a prior art ACC functionality.

[0026] FIGS. 3 and 4 show functional block diagrams of operations carried out by an automotive electronic control unit to implement the ACC functionality according to the present invention.

[0027] FIGS. 5 and 6 show graphical representations of two driving situations in which the ACC functionality according to the present invention allows unnecessary automatic decelerations to be avoided or less conservative automatic decelerations to be carried out.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0028] The present invention will now be described in detail with reference to the attached figures so as to allow a skilled person to create and use it. Various modifications to the described embodiments will be readily apparent to the persons skilled in the art and the general principles described herein may be applied to other embodiments and applications without departing from the protective scope of the present invention as defined in the attached claims. Therefore, the present invention should not be regarded as limited to the embodiments described and illustrated, it should instead be granted the widest protective scope consistent with the characteristics described and claimed.

[0029] FIG. 3 shows a basic functional block diagram of operations carried out by an automotive electronic control unit in order to implement the ACC functionality according to the present invention.

[0030] As can be appreciated from a comparison with the block diagram shown in FIG. 1, compared to the prior art ACC functionality, the ACC functionality according to the present invention is designed to estimate, in the follow mode, the travel trajectory of the leading motor vehicle relative to that of the host motor vehicle, and when it is estimated that the leading motor vehicle is departing from the travel trajectory of the host motor vehicle, to adjust one or more control parameters accordingly based on which the ACC functionality operates in the follow mode.

[0031] The travel trajectory of the leading motor vehicle relative to that of the host motor vehicle for the purpose of determining whether the leading motor vehicle has departed or is departing from the travel trajectory of the host motor vehicle is estimated based on measurable or determinable quantities relating to both the leading motor vehicle, and in particular its distance from the lane centre, and the host motor vehicle, such as its distance from the lane centre, its lateral speed and the activation of a direction indicator, as well as based on the geometry of the road travelled by the host and leading motor vehicles.

[0032] The simplest road geometry can be defined by the road curvature only, which can be stored in digital road maps of an automotive global navigation satellite system, or computed by an automotive front vision system (forward-looking camera) which determines it based on horizontal signs (lane markings) captured by the front vision system.

[0033] More complex road geometries may also include, in addition to the road curvature, the road slope, the number of road lanes, junctions and intersections, etc., this information being provided by advanced automotive global navigation satellite system (electronic horizoneHorizon).

[0034] Once the departure of the leading motor vehicle from the travel trajectory of the host motor vehicle is estimated, the control parameters used by the ACC functionality in the follow mode are modified in such a way as to achieve a less conservative longitudinal control, i.e., in such a way as to avoid unnecessary automatic deceleration of the host motor vehicle or to perform a less conservative automatic deceleration if the leading motor vehicle is departing from the travel trajectory of the host motor vehicle, resulting in a decrease in fuel consumption and in an increased automatic driving comfort.

[0035] Furthermore, in order to increase robustness of the ACC functionality, the present invention conveniently, but not necessarily, also provides for estimating the road adherence of the tyres of the host motor vehicle, thus allowing a more conservative longitudinal control logic to be selected if the environmental conditions differ from, and in particular are worse than, normal or nominal environmental conditions.

[0036] FIG. 4 shows a more detailed functional block diagram of a travel trajectory estimator of the leading motor vehicle relative to that of the host motor vehicle implemented by the automotive ECU.

[0037] As shown in FIG. 4, the travel trajectory estimator receives input data determined by the ECU based on signals from the sensory system of the host motor vehicle (radar, lidar, cameras) and/or stored in the ECU, and indicative of the following parameters:

[0038] the geometry of the road travelled by the host and leading motor vehicles,

[0039] the distance of the host motor vehicle from the lane centre,

[0040] the distance of the leading motor vehicle from the lane centre and the lateral speed of the leading motor vehicle, parameters which can be determined based on signals from the on-board sensory system,

[0041] the activation of a direction indicator of the leading motor vehicle, an operating condition that can be determined based on images from the forward-looking camera.

[0042] The travel trajectory estimator is designed to analyse the travel trajectory of the leading motor vehicle relative to that of the host motor vehicle and the curvature of the road travelled by the hot and leading motor vehicles in order to determine the departure of the leading motor vehicle from the travel trajectory of the host motor vehicle, and thus to determine a consequent change to be made to the values of the longitudinal control parameters of the ACC functionality.

[0043] In particular, in the follow mode, a change in the values of the control parameters may result in a change in one or both of the cruise distance of the host motor vehicle relative to the leading motor vehicle and the acceleration profile of the host motor vehicle.

[0044] The modification of the control parameters can also be made dependent on the type of road travelled, thus differentiating the behaviour of the ACC functionality between urban roads, suburban roads, and motorways. Information on the type of road can be provided to the ECU either by a global navigation satellite system or by an estimator based on the average travel speeds.

[0045] In particular, modification of the cruise distance involves a reduction of the cruise distance, thus allowing the host motor vehicle to go closer to the leading motor vehicle, while modification of the acceleration profile may result in a quicker response of the host motor vehicle to return to the set cruise speed after the leading motor vehicle has departed from the travel trajectory of the host motor vehicle.

[0046] In FIGS. 5 and 6 a driving situation is graphically represented as an example in which a leading motor vehicle is entering a motorway deceleration lane and has consequently activated the direction indicator and its distance from the lave centre is progressively increasing.

[0047] In such a situation, the ACC functionality according to the present invention recognises the progressive departure of the leading motor vehicle from the travel trajectory of the host motor vehicle and consequently progressively reduces the cruise distance that the host motor vehicle is allowed to maintain relative to the leading motor vehicle, thus avoiding unnecessary automatic deceleration of the host motor vehicle or automatically slowing down the host motor vehicle by means of an automatic deceleration profile that is less conservative than the stored one.

[0048] Based on what has been described, the benefits that the present invention allow to achieve may be appreciated.

[0049] In particular, compared to the prior art ACC functionality, the present invention allows the operation of the ACC functionality to me adjusted by acting in particular on the longitudinal control parameters used by the ACC functionality in order to avoid or minimise unnecessary automatic decelerations of the host motor vehicle, or to perform less conservative automatic decelerations of the host motor vehicle if the leading motor vehicle is departing from the travel trajectory of the host motor vehicle, resulting in reduced fuel consumption and in an increased automatic driving comfort.