AUTOMOTIVE ELECTRONIC LATERAL DYNAMICS CONTROL SYSTEM FOR A SELF-DRIVING MOTOR VEHICLE

Abstract

An automotive electronic lateral dynamics control system of an autonomous motor vehicle, comprising a lateral driving path planner designed to plan a lateral driving path of the autonomous motor vehicle and defined by a reference curvature of the autonomous motor vehicle; an automotive electronic driving stability control system designed to control an automotive braking system to apply to the autonomous motor vehicle a yaw torque to hinder a driving instability condition of the autonomous motor vehicle; and an automotive electronic steering control system designed to control an automotive steering system to apply to the autonomous motor vehicle a steering angle or torque to cause the autonomous motor vehicle to follow the lateral driving path planned by the lateral driving path planner. The automotive electronic lateral dynamics control system is designed to cause an intervention of the automotive electronic steering control system to take account of an intervention of the automotive electronic driving stability control system.

Claims

1. An automotive electronic lateral dynamics control system of an autonomous motor vehicle, comprising: a lateral driving path planner designed to plan a lateral driving path of the autonomous motor vehicle and defined by a reference curvature (ρ.sub.ref), a reference heading (∈.sub.ref), and a reference lateral position (y.sub.l.sub.ref) of the autonomous motor vehicle; an automotive electronic driving stability control system designed to control an automotive braking system to apply to the autonomous motor vehicle a yaw torque (δ.sub.sw.sub.ref) to hinder a driving instability condition of the autonomous motor vehicle; and an automotive electronic steering control system designed to control an automotive steering system to apply to the autonomous motor vehicle a steering angle or torque (δ.sub.sw.sub.ref , T.sub.sw.sub.ref) to cause the autonomous motor vehicle to follow the lateral driving path planned by the lateral driving path planner; wherein the automotive electronic lateral dynamics control system is designed to cause an intervention of the automotive electronic steering control system to take account of an intervention of the automotive electronic driving stability control system by: the planned lateral driving path of the autonomous motor vehicle being computed based on automotive quantities either measured or computed based on measured automotive quantities and indicative of: a current lateral driving path of the autonomous motor vehicle and defined by a road curvature (ρ) and heading (∈) and lateral position (y.sub.l) of the autonomous motor vehicle, and a current dynamic state of the autonomous motor vehicle and defined by a yaw rate ({dot over (ψ)}), a lateral acceleration (a.sub.y), a longitudinal speed (V.sub.x), and a steering angle (δ.sub.sw); and the steering angle or torque (δ.sub.sw.sub.ref, T.sub.sw.sub.ref) to be applied by the automotive steering system to the autonomous motor vehicle to cause it to follow the planned lateral driving path being computed based on the automotive quantities that define the planned lateral driving path of the autonomous motor vehicle and on a reference yaw rate ({dot over (ψ)}.sub.ref)computed based on the reference curvature (ρ.sub.ref) of the planned lateral driving path and on a longitudinal speed (V.sub.x) of the autonomous motor vehicle.

2-6. (canceled)

7. The automotive electronic lateral dynamics control system of claim 1, further designed to compute: by means of a state observer, observed automotive quantities comprising an observed heading ({circumflex over (∈)}), an observed lateral position (ŷ.sub.l), an observed yaw rate ({circumflex over ({dot over (ψ)})}), and an observed lateral speed ({circumflex over (V)}.sub.y) of the autonomous motor vehicle; the observed automotive quantities are either computed by filtering, or estimated based on, the measured heading (∈), the road curvature (ρ) ahead of the autonomous motor vehicle, and the lateral position (y.sub.l) of the autonomous motor vehicle, which define the current driving path of the autonomous motor vehicle, the yaw rate ({dot over (ψ)}), the longitudinal speed (V.sub.x) of the autonomous motor vehicle, and the steering angle or torque (δ.sub.sw.sub.ref, T.sub.sw.sub.ref) to be applied by the automotive steering system to the autonomous motor vehicle to cause it to follow the planned lateral driving path; a yaw rate error ({dot over (ψ)}.sub.err) based on the reference yaw rate ({dot over (ψ)}.sub.ref) and on the observed yaw rate ({circumflex over ({dot over (ψ)})}) of the autonomous motor vehicle; a heading error (∈.sub.err) based on the reference heading (∈.sub.ref) and the observed heading ({circumflex over (∈)}) of the autonomous motor vehicle; a lateral position error ((y.sub.l.sub.err)) based on the reference lateral position (y.sub.l.sub.ref) and the observed lateral position (ŷ.sub.l) of the autonomous motor vehicle; by means of a state feedback controller, a closed-loop contribution (δ.sub.sw.sub.CL) to the steering angle (δ.sub.sw.sub.ref) based on the yaw rate error, heading error, and lateral position error ({dot over (ψ)}.sub.err, ∈.sub.err, y.sub.l.sub.err) and on the observed lateral speed ({circumflex over (V)}.sub.y) of the autonomous motor vehicle; by means of an open-loop state controller, an open-loop contribution (δ.sub.sw.sub.OL) to the reference steering angle (δ.sub.sw.sub.ref) based on the reference curvature (ρ.sub.ref) of the planned lateral driving path and the longitudinal speed (V.sub.x) of the autonomous motor vehicle; and the reference steering angle (δ.sub.sw.sub.ref) based on the closed-loop and open-loop contributions (δ.sub.sw.sub.CL, δ.sub.sw.sub.OL) to the reference steering angle (δ.sub.sw.sub.ref).

8. The automotive electronic lateral dynamics control system of claim 7, wherein the state observer and/or the state feedback controller are time-variant.

9. An autonomous motor vehicle comprising the automotive electronic lateral dynamics control system of claim 1.

10. A software loadable in one or more automotive electronic control units of an automotive electronic lateral dynamics control system of an autonomous motor vehicle, and designed to cause, when run, the automotive electronic lateral dynamics control system of the autonomous motor vehicle to become configured as claimed in claim 1.

11. The automotive electronic lateral dynamics control system of claim 1, further designed to cause the yaw torque (T.sub.yaw.sub.ref) to be computed by the automotive electronic driving stability control system, and the steering angle or torque (δ.sub.sw.sub.ref, T.sub.sw.sub.ref) to be computed in a different automotive system.

12. The automotive electronic lateral dynamics control system of claim 1, further designed to cause the steering angle or torque (δ.sub.sw.sub.ref, T.sub.sw.sub.ref) and the yaw torque (T.sub.yaw.sub.ref) to be computed by the automotive electronic driving stability control system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG. 1 shows a block diagram of a high-level architecture of an automotive advanced electronic system for controlling driving stability of an autonomous self-driving motor vehicle, according to a first embodiment of the present invention.

[0036] FIG. 2 shows a detailed block diagram of the automotive advanced electronic control system shown in FIG. 1.

[0037] FIG. 3 shows a block diagram of a high-level architecture of an automotive advanced electronic system for controlling driving stability of an autonomous self-driving motor vehicle according to a second embodiment of the present invention.

[0038] FIG. 4 shows a detailed block diagram of the automotive advanced automotive electronic control system shown in FIG. 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0039] The present invention will now be described in detail with reference to the attached figures so as to allow a person skilled in the art 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 shown; it should, instead, be granted the widest protective scope consistent with the features described and claimed.

[0040] In a nutshell, the present invention essentially provides for coordinating the operation of the automotive electronic steering control system, hereinafter referred to as EPS (Electric Power Steering) system for the sake of brevity, with the operation of the automotive electronic driving stability control system, hereinafter referred to as ESC (Electronic Stability Control) system for the sake of brevity, so that the ESC and EPS systems synergistically co-operate to create an integrated automotive electronic control system for controlling the lateral dynamics of an autonomous motor vehicle, and in which the intervention of the EPS system takes account of the intervention of the ESC system on the motor vehicle.

[0041] As is well known, in fact, an ESC system for a manually-driven motor vehicle is designed to detect the occurrence of a motor vehicle driving instability condition and, when detected, to compute a yaw torque T.sub.yaw.sub.ref that is to be applied to the motor vehicle in order to hinder the motor vehicle's driving instability, and to control accordingly the automotive braking system to cause the yaw torque T.sub.yaw.sub.ref to be applied to the motor vehicle to hinder the motor vehicle's driving instability.

[0042] An EPS system of an autonomous or manually-driven motor vehicle is designed to receive a steering command for the automotive steering system in the form of either a steering angle δ.sub.sw.sub.ref that the wheels or the steering column of the motor vehicle have to follow, or a steering torque T.sub.sw.sub.ref that is to be applied to the steering column of the motor vehicle to cause the motor vehicle to follow a planned lateral driving path, and to control accordingly the automotive steering system based on the steering command to cause either the steering angle δ.sub.sw.sub.ref or torque tT.sub.sw.sub.ref to be applied to the wheels or the steering column of the motor vehicle so as to result in the motor vehicle driving the planned lateral driving path.

[0043] In a first embodiment shown in FIGS. 1 and 2, the interventions of the ESC and EPS systems are coordinated without making changes to the logical architecture of the ESC system, but acting only on the logical architecture of the EPS system, so as to cause the intervention of the EPS system to take into account the intervention of the ESC system, thus basically representing an incremental improvement of the ESC system.

[0044] In a second, more advanced embodiment of the invention, shown in FIGS. 3 and 4, the interventions of the ESC and EPS systems are coordinated by changing the logical architectures of both the ESC and EPS systems, thus representing a re-thinking of the logical architectures thereof.

[0045] With reference to the first embodiment of the invention, FIG. 1 shows a block diagram of an integrated automotive electronic control system for controlling the lateral dynamics of an autonomous motor vehicle, referenced as a whole with reference numeral 1. In particular, FIG. 1 shows from an architectural point of view the domains of the ESC system, referenced with reference numeral 2, of the EPS system, references with reference numeral 3, and of the Autonomous Driving

[0046] System, hereinafter referred to as ADS for the sake of brevity and referenced with reference number 4, which is designed to compute a reference steering angle δ.sub.sw.sub.ref for the EPS 3 system.

[0047] As shown in FIG. 1, the ESC system 2 receives a series of automotive quantities measured through an automotive sensory system or otherwise computed based on measured quantities and hereinafter both referred to as measured automotive quantities for the sake of convenience. The measured automotive quantities comprise, among others, the yaw rate {dot over (ψ)}, the lateral acceleration a.sub.y, the angular wheel speed ω.sub.wheel, the steering angle δ.sub.sw, and the steering speed {dot over (δ)}.sub.sw. Based on the received measured automotive quantities, the ESC system 2 is designed to compute a braking command for the automotive braking system in the form of a brake pressure P.sub.wheel to be applied to the brake calipers to cause a corresponding yaw torque T.sub.yaw.sub.ref to be applied to the autonomous motor vehicle.

[0048] The ADS system 4 receives the measured automotive quantities {dot over (ψ)}, a.sub.y,V.sub.x, δ.sub.sw, ρ, ∈, y.sub.l, where ∈ is the heading of the motor vehicle relative to the longitudinal axis of the motor vehicle, ρ is the road curvature ahead of the motor vehicle, y.sub.l is the lateral position of the motor vehicle relative to a planned driving path of the motor vehicle, wherein the latter three measured automotive quantities jointly define the position of the motor vehicle in a reference system of the motor vehicle, and V.sub.x is the longitudinal speed of the motor vehicle computed based on ω.sub.wheel.

[0049] Based on the received measured automotive quantities, the ADAS system 4 computes a steering angle δ.sub.sw.sub.ref for the EPS system 3 to cause the autonomous motor vehicle to follow the planned lateral driving path.

[0050] The EPS system 3 receives the computed reference steering angle δ.sub.sw.sub.ref, , the measured steering angle, δ.sub.sw and the measured steering speed {dot over (δ)}.sub.sw , and based on these automotive quantities the EPS system 3 computes a steering command for the automotive steering system in the form of an electric current i.sub.sw to be supplied to an electric actuator of the automotive steering system so as to cause a steering torque to be applied to the steering column of the autonomous motor vehicle and, resultingly, the latter to achieve a corresponding steering angle δ.sub.sw.sub.ref so as to result in the autonomous motor vehicle following the planned lateral driving path.

[0051] In particular, the ESC system 2 is designed to:

[0052] detect occurrence of an instability condition of the autonomous motor vehicle based on {dot over (ψ)}, a.sub.y, δ.sub.sw, {dot over (δ)}.sub.sw (block 10),

[0053] when occurrence of an instability condition of the autonomous motor vehicle is detected, compute a yaw torque T.sub.yaw.sub.ref to be applied to the autonomous motor vehicle and that is to be followed, as described below (block 20),

[0054] compute a longitudinal force that the wheels of the autonomous motor vehicle have to exert on the ground and associated target wheel spins σ.sub.ref (block 30), and

[0055] compute and apply a brake pressure P.sub.wheel to the individual wheels in order to achieve the associated σ.sub.ref (block 40).

[0056] The ADS system 4 is designed to:

[0057] compute, based on {dot over (ψ)}, a.sub.y, V.sub.x, δ.sub.sw, ρ, ∈, y.sub.l, a planned lateral driving path to be followed by the autonomous motor vehicle and defined by a number of automotive quantities comprising a reference curvature ρ.sub.ref, a reference heading ∈.sub.ref, and a reference lateral position y.sub.l.sub.ref (block 50),

[0058] compute the steering angle δ.sub.sw.sub.ref based on the automotive quantities which define the planned driving path of the autonomous motor vehicle (block 60).

[0059] In particular, in an autonomous motor vehicle, the planned lateral driving path is computed by a lateral driving path planner which is part of the autonomous driving system of the autonomous motor vehicle and which operates based on a proprietary lateral driving path planning algorithm which is specifically developed by the automotive manufacturer and which, therefore, is usually different for different automotive manufacturers.

[0060] The EPS system 3 is designed to:

[0061] compute, based on the steering angle δ.sub.sw.sub.ref , the steering torque T.sub.sw.sub.ref to be applied to the steering column of the autonomous motor vehicle in order to achieve the steering angle δ.sub.sw.sub.ref (block 70).

[0062] compute and supply the automotive steering system with a steering command in the form of an electric current i.sub.sw required to actuate the computed steering command.

[0063] FIG. 2 shows a detailed functional block diagram of the functional blocks of the first embodiment of the invention shown in FIG. 1 enclosed within the dashed area, and where the blocks are to be considered merely representative of the functions performed and not limited to a particular circuit architecture.

[0064] In particular, as described above, the ESC system 2 is designed to:

[0065] receive {dot over (ψ)}, a.sub.y, ω.sub.wheel, δ.sub.sw, {dot over (δ)}.sub.sw,

[0066] detect, based on the received automotive quantities, occurrence of an instability condition of the autonomous motor vehicle, and

[0067] when occurrence of an instability condition of the autonomous motor vehicle is detected, compute T.sub.yaw.sub.ref based on the received automotive quantities.

[0068] The steering angle δ.sub.sw.sub.ref computation block 60 comprises:

[0069] a state observer 61, conveniently a time-variant one, configured to receive ρ, ∈, y.sub.l, {dot over (ψ)}, V.sub.x and δ.sub.sw.sub.ref or, alternatively, δ.sub.sw, and to output observed automotive quantities {circumflex over (∈)}, ŷ.sub.l, {circumflex over ({dot over (ψ)})}, {circumflex over (V)}.sub.ywhere {circumflex over (V)}.sub.y is the lateral speed of the autonomous motor vehicle, which are either computed by filtering corresponding measured automotive quantities or estimated based on other measured automotive quantities, so as to be also mutually phased, i.e. correlated and consistent with each other,

[0070] a yaw rate reference generator 62 configured to receive ρ.sub.refe V.sub.x and compute and output a reference yaw rate {dot over (ψ)}.sub.ref based on ρ.sub.rep, e V.sub.x and on a model known in the literature, the simplest of which is represented by the product of ρ.sub.ref and V.sub.x,

[0071] a first subtractor 63 configured to receive and subtract {dot over (ψ)}.sub.ref and {circumflex over ({dot over (ψ)})}, thus outputting a yaw rate error {dot over (ψ)}.sub.err,

[0072] a second subtractor 64 configured to receive and subtract ∈.sub.ref e {circumflex over (∈)} and y.sub.l.sub.ref e ŷ.sub.l, thus outputting associated heading and lateral position errors ∈.sub.err e y.sub.l.sub.err of the autonomous motor vehicle,

[0073] a state feedback controller 65 configured to receive {dot over (ψ)}.sub.err, ∈.sub.err, y.sub.l.sub.err, {circumflex over (V)}.sub.y and compute and output a closed-loop contribution δ.sub.sw.sub.CL to the steering angle δ.sub.sw.sub.ref based on {dot over (ψ)}.sub.err, ∈.sub.err, y.sub.l.sub.err, {circumflex over (V)}.sub.y and on a state model known in the literature, the simplest of which is represented by an appropriate vector of gains K.sub.SW.sub.s1 to linearly combine {dot over (ψ)}.sub.err, ∈.sub.err, y.sub.l.sub.err, {circumflex over (V)}.sub.y;

[0074] an open-loop controller 66 configured to receive ρ.sub.ref and V.sub.x and compute and output an open-loop or feed forward contribution δ.sub.sw.sub.OL to the steering angle δ.sub.sw.sub.ref based on ρ.sub.ref and V.sub.x and on one of the models known in the literature, in order to speed up the time response of the control logic and improve the compensation capability of ρ, and

[0075] a summation unit 67 configured to receive and sum δ.sub.sw.sub.CL and δ.sub.sw.sub.OL, thus outputting δ.sub.sw.sub.ref

[0076] With reference to the second embodiment of the invention, FIG. 3 shows from an architectural point of view the domains of the ESC system 2, the EPS system 3, and the ADS system 4.

[0077] A comparison between the architectures shown in FIGS. 1 and 3 shows that the second embodiment of the invention differs from the first embodiment shown in FIG. 1 in the yaw torque T.sub.yaw.sub.ref and the steering angle δ.sub.sw.sub.ref being computed, instead of separately in the ESC system 2 and the ADS system 4, respectively, both in the ESC system 2 (block 70), which becomes the controller of both the braking system and the steering system of the autonomous motor vehicle.

[0078] In the second embodiment of the invention, in addition, the ESC system 2 receives {dot over (ψ)}, a.sub.y, ω.sub.wheel, δ.sub.sw, {dot over (δ)}.sub.sw, ρ, ∈, y.sub.l, while the ADS system 4 receives {dot over (ψ)}, a.sub.y, V.sub.x, δ.sub.sw, {dot over (δ)}.sub.sw, ρ, ∈, y.sub.l.

[0079] Consequently, the logical architecture of the first embodiment of the invention shown in FIG. 2 transforms into that shown in FIG. 4, in which the state feedback controller 65 integrates the functionalities of the blocks 10 and 20.

[0080] As shown in FIG. 4, the state feedback controller 65 is designed to receive, in addition to {dot over (ψ)}.sub.err, ∈.sub.err, y.sub.l.sub.err, {circumflex over (V)}.sub.y, also δ.sub.sw, {dot over (ψ)}, a.sub.y, V.sub.x to detect the occurrence of an instability condition of the autonomous motor vehicle and, when such a condition is detected, to compute the yaw torque T.sub.yaw.sub.ref , which is also inputted to the state observer 61 to allow it to compute {circumflex over (∈)}, ŷ.sub.l, {circumflex over ({dot over (ψ)})}, {circumflex over (V)}.sub.y.

[0081] In this embodiment, the state feedback controller 65, which can conveniently be time-variant and, in order to be so, needs to receive V.sub.x, is designed to compute and output:

[0082] δ.sub.sw.sub.CL based on a gain matrix selected between two different gain vectors K.sub.sw.sub.s1, and K.sub.sw.sub.s2 depending on whether or not occurrence of an instability condition of the autonomous motor vehicle is detected, and

[0083] T.sub.yaw.sub.ref based on a gain matrix selected between two different gain vectors K.sub.ty.sub.s1 and K.sub.ty.sub.s2 depending on whether or not occurrence of an instability condition of the autonomous motor vehicle is detected.