System and method for determining a trailer angle for steering a vehicle with active rear-wheel steering

Abstract

System (10) which includes: a memory configured to contain one or more executable instructions, and a processor configured to execute the executable instructions, wherein the executable instructions enable the processor to: estimates the rate of change of a trailer angle between a trailer (14) and a vehicle (12), wherein the estimated rate of change of the trailer angle is based on a steering angle for several rear wheels (26, 28) of the vehicle (12) and the speed of the vehicle (12); characterized by the fact that The estimated rate of change of the attachment angle is based on the following relationship: θ ˙ = VC ltr sin (α − θ prev) − ω (lhltr cos θ prev + 1) where θ̇̇ is the rate of change of the estimated attachment angle, θ preva previous trailing angle, α a rear wheel steering angle, ω an angular velocity of the vehicle (12), V c the speed of the vehicle (12) is, l h a distance from a rear axle of the vehicle (12) to a trailer coupling of the vehicle (12) is and l tr a distance from a trailer coupling of the vehicle (12) to an axle of the trailer (14).

Description

[0001] The present invention relates to a system according to the preamble of claim 1 and a method according to the preamble of claim 6 for determining a rate of change of a trailer angle, as known essentially from the generic DE 10 2006 059 082 A1 or DE 10 2011 015 033 A1. Further prior art can also be found in the documents DE 10 2017 125 662 A1 and DE 10 2019 105 408 A1.

[0002] Advanced driver assistance systems were developed to assist vehicle operators (drivers) when towing a trailer. These assistance systems can, for example, predict hitch angles and generate guidance graphics while a vehicle and trailer are reversing. Unfortunately, these advanced driver assistance systems only consider vehicles that implement front-wheel steering functionality. Such advanced driver assistance systems are incompatible with vehicles that incorporate active rear-wheel steering systems.As follows, when the rear wheels of a vehicle are effectively turned to impart greater stability and control for parking the vehicle and trailer and handling off-road trailer operation, known driver assistance system modules may not correctly predict the trailer's hitch angles and consequently fail to provide accurate steering assistance and guidance graphics on one or more displays within the vehicle interior. These inaccurate driver assistance system modules create, for example, an overlay mismatch and interference in the views of any unseen trailer attachments and trailer turning aids incorporated into the vehicle. Therefore, it is desirable to provide a system and method that facilitates accurate driver (user) assistance when towing a trailer (forward and backward) with a vehicle incorporating an active rear steering system.

[0003] A system of one or more computers may be configured to perform specific operations or acts by including software, firmware, hardware, or a combination thereof installed on the system that, in operation, causes the system to perform the acts. One or more computer programs may be configured to perform specific operations or acts by including instructions that, when executed by a data processing device, cause the device to perform the acts.A general aspect includes a system having a memory configured to include one or more executable instructions and a processor configured to execute the executable instructions, wherein the executable instructions enable the processor to estimate a rate of change of a hitch angle between a trailer and a vehicle, the estimated rate of change of the hitch angle being based on a turning angle for a plurality of rear wheels of the vehicle and a speed of the vehicle. Other embodiments of this aspect include corresponding computer systems, devices, and computer programs recorded on one or more computer storage devices, each configured to perform the acts of the methods.

[0004] According to the invention, a system is presented which is characterized by the features of claim 1. In the system, the estimated rate of change of the trailer angle is based on the following relationship: θ˙=VCltrsin(α−θprev)−ω(lhltrcosθprev+1), where θ̇ is the estimated rate of change of the trailer angle, θ prev is a previous trailer angle, α is a rear wheel steering angle, ω is an angular velocity of the vehicle, V c the speed of the vehicle is l h a distance from a rear axle of the vehicle to a trailer coupling of the vehicle and l tr a distance from the vehicle's tow bar to an axle of the trailer.

[0005] The system wherein the executable instructions further enable the processor to predict a first radius of curvature of movement of the vehicle and trailer based on a previous hitch angle; and predict a second radius of curvature of movement of the vehicle and trailer based on the estimated rate of change of the hitch angle. The system wherein the first radius of curvature and the second radius of curvature are based on the following relationships: R B = (l h cos α + l tr cos(α - θ prev )) / sin(α - θ prev ) and R Y = (l h cos α + l tr cos(α - θ d )) / sin(α - θ d ), where R B the first radius of curvature is R Y the second radius of curvature is, θ d is a predicted trailer angle at a selected distance from a current location of the trailer, α is a rear wheel steering angle, l ha distance from a rear axle of the vehicle to a trailer coupling of the vehicle and l tra distance from a trailer hitch of the vehicle to an axle of the trailer. The system wherein the executable instructions further enable the processor to generate a visible trailer return trajectory view based on the estimated rate of change of hitch angle, the trailer return trajectory configured to provide one or more virtual lines on a camera view to assist a driver in controlling movement of the trailer. The system wherein the executable instructions further enable the processor to control an active rear steering actuator based on the estimated rate of change of hitch angle to steer the vehicle to assist a vehicle operator.The system wherein the executable instructions further enable the processor to control one or more friction brakes of the vehicle and / or one or more friction brakes of the trailer based on the estimated rate of change of the hitch angle to assist in controlling an active rear steering actuator. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.

[0006] A general aspect includes a non-transitory machine-readable medium having stored thereon executable instructions configured to estimate a rate of change of a hitch angle, which, when delivered to and executed by a processor, cause the processor to estimate a rate of change of the hitch angle between a trailer and a vehicle, wherein the estimated rate of change of the hitch angle is based on a turning angle for a plurality of rear wheels of the vehicle and a speed of the vehicle. Other embodiments of this aspect include corresponding computer systems, devices, and computer programs recorded on one or more computer storage devices, each configured to perform the acts of the methods.

[0007] Furthermore, according to the invention, a method is presented which is characterized by the features of claim 6.

[0008] Implementations may include one or more of the following features. The method in which the estimated rate of change of the hitch angle is based on the following relationship: θ˙=VCltrsin(α−θprev)−ω(lhltrcosθprev+1), where θ̇ is the estimated rate of change of the trailer angle, θ prev is a previous trailer angle, α is a rear wheel steering angle, ω is an angular velocity of the vehicle, V c the speed of the vehicle is l h a distance from a rear axle of the vehicle to a trailer coupling of the vehicle and l tra distance from a trailer hitch of the vehicle to an axle of the trailer. The method further comprising the steps of predicting a first radius of curvature of movement of the vehicle and trailer based on a previous hitch angle; and predicting a second radius of curvature of movement of the vehicle and trailer based on the estimated rate of change of hitch angle. The method wherein the first radius of curvature and the second radius of curvature are based on the following relationships: R B = (l h cos α + l tr cos(α - θ prev )) / sin(α - θ prev ) and R Y = (l h cos α + l tr cos(α - θ d )) / sin(α - θ d ), where R B the first radius of curvature is R Y the second radius of curvature is, θ dis a predicted trailer angle at a selected distance from a current location of the trailer, α is a rear wheel steering angle, l h a distance from a rear axle of the vehicle to a trailer coupling of the vehicle and l tra distance from a trailer hitch of the vehicle to an axle of the trailer. The method further comprising the step of generating a visible trailer return trajectory view based on the estimated rate of change of hitch angle, the trailer return trajectory configured to provide one or more virtual lines on a camera view to assist a driver in controlling movement of the trailer. The method further comprising the step of controlling an active rear steering actuator based on the estimated rate of change of hitch angle to steer the vehicle to assist a vehicle operator. Implementations of the described techniques may comprise hardware, a method, or a processor, or computer software on a computer-accessible medium.

[0009] The disclosed examples are described below in conjunction with the following drawing figures, wherein like reference numerals denote like elements; Fig. 1 is a diagram of an example vehicle system capable of using the system and method disclosed herein; Fig. 2 is a functional block diagram of an example vehicle control system capable of using the system and method disclosed herein; Fig. 3 Parameters associated with an example vehicle system capable of using the system and method disclosed herein; Fig. 4 Parameters associated with an example vehicle system capable of using the system and method disclosed herein; Fig. 5 is a flowchart illustrating an exemplary method according to the principles disclosed herein; and Fig. 6 an explanatory aspect of the schedule of Fig. 5.

[0010] A vehicle control system according to the present disclosure determines the hitch angle using both a kinematic model and input from one or more sensors and assists a driver of a vehicle with active rear steering (ARS) based on the determined hitch angle. In one example, the vehicle control system determines a corrected hitch angle based on a measured hitch angle and an estimated rate of change of the hitch angle and assists the driver based on the corrected hitch angle. In another example, the vehicle control system determines the corrected hitch angle based on the measured and estimated rates of change of the hitch angles using a Kalman filter.

[0011] The vehicle control system determines the estimated rate of change of the trailer angle based on a rear wheel steering angle of the vehicle, the speed of the vehicle at the center of the rear axle and the angular velocity of the vehicle via a kinematic model of the vehicle and the trailer.

[0012] With reference now to Fig. 1, a vehicle system 10 includes a vehicle 12 and a trailer 14. The vehicle 12 has a front end 15 and a rear end 16. The vehicle 12 includes a frame or body 18, a front axle 20, a rear axle 22, front wheels 24, a left rear wheel 26, a right rear wheel 28, friction brakes 30, a steering system 32, and a trailer hitch 34. The vehicle 12 further includes a rear wheel speed sensor 36, a steering wheel angle sensor 38, a user interface device 42, and a vehicle control module (VCM) 44.

[0013] The front axle 20 may refer to any one or more shafts extending between and rotatably coupled to the front wheels 24. Likewise, the rear axle 22 may refer to any one or more shafts extending between and rotatably coupled to the left and right rear wheels 26 and 28.

[0014] The friction brakes 30 are mounted on the front wheels 24 and the left and right rear wheels 26 and 28. The friction brakes 30 resist the rotation of the wheels 24, 26, and 28 when the friction brakes 30 are applied. The friction brakes 30 may include drum brakes and / or disc brakes and may include electro-hydraulic actuators and / or electromechanical actuators that press a brake pad against a brake disc and / or brake drum when the friction brakes 30 are applied.

[0015] The steering system 32 is operable to turn the left and right front wheels 26 and 28 and thereby turn the vehicle 12. The steering system 32 includes a steering wheel 46, a steering column 48, one or more steering linkages 50, a steering actuator 52, one or more ARS linkages 51, and an active rear steering actuator 53. A driver turns the steering wheel 46 to turn the vehicle 12 left or right. The steering column 48 is coupled to the steering wheel 46 such that the steering column 48 rotates when the steering wheel 46 is turned. The steering column 48 may also be coupled to the steering linkages 50 such that rotation of the steering column 48 causes translation of the steering linkages 50. The steering linkages 50 are coupled to the front wheels 24 so that the translation of the steering linkages 50 turns the front wheels 24.

[0016] The steering actuator 52 is coupled to the steering linkages 50 and is operative to translate the steering linkages 50 and thereby turn the front wheels 24. The steering actuator 52 may be an electro-hydraulic and / or electromechanical actuator. When the steering column 48 is coupled to the steering linkages 50, the steering actuator 52 may reduce the amount of force the driver must exert to turn the vehicle 12 left or right. In various implementations, the steering column 48 may not be coupled to the steering linkages 50, and the steering actuator 52 may translate the steering linkages 50 in response to an electronic signal generated based on the angular position of the steering wheel 46. When the steering actuator 52 is electronically controlled in this manner, the steering system 32 may be referred to as a steer-by-wire system.

[0017] Similar to the steering actuator 52 discussed above, the active rear steering actuator 53 is coupled to ARS linkages 51 and is operative to translate the ARS linkages 51 and thereby angularly turn the right and left rear wheels 26 and 28. The active rear steering actuator 53 may be an electrohydraulic and / or electromechanical actuator. In various implementations, the active rear steering actuator 53 is operatively connected to the steering column 48 and / or the steering actuator 52, which may occur via wireless communications. As such, the active rear steering actuator 53 may translate the ARS linkages 51 in response to an electronic signal generated based on the angular position of the steering wheel 46.Furthermore, the active rear steering actuator 53 can translate the ARS linkages 51 so that the right and left rear wheels 26 and 28 turn in an opposite direction to the front wheels 26. As such, the right and left rear wheels 26 have an inverse turning relationship to the front wheel 24 (as described with additional reference to FIG. Fig. 3). The active rear steering actuator 53 may include an embedded rear steering sensor configured to measure the angular position of the right and left rear wheels 26 and 28 relative to a predetermined position. The rear steering angle sensor may alternatively be a standalone component mounted to the ARS linkages 51, the rear axle, or the steering column 48 (or may be embedded within the steering wheel angle sensor 38). When mounted on the steering column 48, the rear steering wheel angle sensor may comprise a Hall-effect sensor that measures the angular position of a shaft disposed within the steering column 48 and rotatably coupled to the steering wheel 46.

[0018] The wheel speed sensor 36 is mounted on the left rear wheel 26 and measures the speed of the left rear wheel 26 (e.g., in meters per second m / s). Although the wheel speed sensor 36 is shown mounted on the left rear wheel 26, the wheel speed sensor 36 may measure the speed of another wheel of the vehicle 12 (e.g., the right rear wheel 28). In various implementations, the vehicle 12 may include a speed sensor along the ARS linkage 51 or in the center of the rear axle to measure the speed at the center of the rear axle of the vehicle 12.

[0019] The steering wheel angle sensor 38 measures the angular position of the steering wheel 46 relative to a predetermined position. The steering wheel 46 may be in the predetermined position when the vehicle 12 is traveling in a straight line. The steering wheel angle sensor 38 may be mounted on the steering column 48 and may include a Hall-effect sensor that measures the angular position of a shaft disposed within the steering column 48 and rotatably coupled to the steering wheel 46.

[0020] A camera 40 may be permanently mounted on one of the side view mirrors of the vehicle 12 (not shown), on the rear end 64 of the trailer 14, or on the roof of the trailer 14. The camera 40 may capture one or more images of the area behind the trailer 14. The user interface device 42 may include an electronic display (e.g., a touchscreen) located within the driver's line of sight and operable to display text and / or images. Additionally, the user interface device 42 may include a head-up display (HUD) that projects, for example, text and / or images onto a windshield (not shown) of the vehicle 12. Furthermore, the user interface device 42 may include one or more vibrators mounted, for example, on the steering wheel 46 and / or the driver's seat (not shown) to provide haptic feedback to the driver.Furthermore, the user interface device 42 may include a speaker operable to generate a sound or audible message within the vehicle 12.

[0021] The VCM 44 estimates a rate of change of a hitch angle 56 (i.e., an angle between a longitudinal axis 58 of the vehicle 12 and a longitudinal axis 60 of the trailer 14) and assists the vehicle operator (or vehicle driver / user) in various ways, for example, associated with preventing / avoiding a skid-out scenario while reversing the vehicle 12, based on the estimated rate of change of the hitch angle. The VCM 44 may assist the driver by controlling the user interface device 42 to instruct the driver when to turn and / or brake the vehicle 12, in which direction to turn the vehicle 12, and / or how hard to turn and / or brake the vehicle 12.Additionally or alternatively, the VCM 44 may assist the driver by controlling the user interface device 42 to generate a combined rear view image depicting an area behind the vehicle 12 while mitigating a disturbance caused by the trailer 14. Additionally or alternatively, the VCM 44 may assist the driver by automatically turning and / or decelerating the vehicle 12 (e.g., by applying the friction brakes 30 and / or turning the front wheels 24 and / or the left and right rear wheels 26 and 28 independent of input from the driver). The VCM 44 may automatically turn and / or decelerate the vehicle 12 to prevent the skid-out scenario while the vehicle is in reverse, as well as to provide additional stability and control while towing the trailer 14 (which may include both on-highway and off-highway trailer applications).The VCM 44 also estimates the rate of change of the trailer angle 56 based on a turning angle for the right and left rear wheels 26 and 28, as well as the speed of the vehicle 12, which may be sensed at the center of the rear axle 22 (discussed below). Additionally, the VCM 44 may include an internal measurement unit (IMU) that measures specific force, angular rate, and orientation of the vehicle 12, which may be done via a combination of accelerometers, gyroscopes, and magnetometers.

[0022] The trailer 14 has a front end 62 and a rear end 64. The camera 40 can capture images of an area located directly behind the rear end 64 of the trailer 14. The trailer 14 includes a frame or body 66, an axle 68, wheels 70, friction brakes 72, and a tongue 74. Although the trailer 14 is illustrated as a two-wheeled trailer, the principles of the present application apply to a trailer having more than two wheels. The axle 68 may refer to one or more shafts extending between and rotatably coupled to the wheels 70, or the axle 68 may simply refer to the wheels 70.

[0023] The friction brakes 72 are mounted on the wheels 70 and resist rotation of the wheels 70 when the friction brakes 72 are applied. The friction brakes 72 may include drum brakes and / or disc brakes and may include electro-hydraulic actuators and / or electromechanical actuators that press a brake pad against a brake disc and / or brake drum when the friction brakes 72 are applied. The tongue 74 may be disposed on the trailer hitch 34 of the vehicle 12 to couple the trailer 14 to the vehicle 12. The trailer hitch 34 may, for example, comprise a ball, and the tongue 74 may include a socket that receives and locks to the ball of the trailer hitch 34 to couple the trailer 14 to the vehicle 12. The coupling 34 may also include a sensor to detect a hitch angle, which for purposes herein is referred to as the previous hitch angle (θ prev) detected at a time prior to the rotation of the rear wheels 26 and 28 (ie, at a time T0). Those skilled in the art will appreciate that the trailer angle can generally be considered the articulation angle of the trailer 14.

[0024] As discussed above, the VCM 44 may assist the driver by automatically decelerating the vehicle 12, which may be accomplished by applying the friction brakes 30 of the vehicle 12. Of course, when the trailer 14 is attached to the vehicle 12, decelerating the vehicle 12 will decelerate the trailer 14, and vice versa. Thus, instead of or in addition to applying the friction brakes 30 of the vehicle 12 independently of driver input, the VCM 44 may automatically decelerate the vehicle 12 by applying the friction brakes 72 of the trailer 14 independently of driver input.

[0025] With reference now to Fig. 2, an example implementation of the VCM 44 includes an estimated hitch angle rate of change module 102 and a curvature prediction module 104. The estimated hitch angle rate of change module 102 estimates a hitch angle rate of change 56 based on a turning angle of the right and left rear wheels 26 and 28, the speed of the vehicle 12 (which may be sensed at the center of the rear axle 22), and the angular velocity of the vehicle 12 (which may also be sensed at the center of the rear axle 22). The estimated hitch angle rate of change module 102 receives the speed of the vehicle 12 from the wheel speed sensor 36. The estimated hitch angle rate of change module 102 receives the angular velocity of the vehicle 12 from the IMU of the VCM 44.

[0026] The first rear wheel steering angle of the vehicle 12 is in Fig. 3 is designated 76 and is an angle between a line 78 parallel to the longitudinal axis 58 of the vehicle 12 and a vertical plane 80 extending through a steered left rear wheel of the vehicle 12 (ie, the left rear wheel 26). The second rear wheel steering angle of the vehicle 12 is in Fig. 3, and is an angle between a line 79 parallel to the longitudinal axis 58 of the vehicle 12 and a vertical plane 81 extending through a steered right rear wheel of the vehicle 12 (i.e., the right rear wheel 28). The estimated trailer angle rate of change module 102 determines the rear wheel steering angle 76 based on the steering wheel angle measured by the output from the rear steering angle sensor of the active rear steering actuator 53. For example, when mounted on the steering column 48, the estimated trailer angle rate of change module 102 may multiply the steering wheel angle by a conversion factor (i.e., a predetermined value) to obtain the rear wheel steering angle 76.

[0027] The estimated hitch angle rate of change module 102 estimates the rate of change of the hitch angle 56 based on the rear wheel steering angle 76, the vehicle speed, and the angular velocity of the vehicle 12 using a kinematic model of the vehicle 12 and the trailer 14 (taken at a time T1). The estimated hitch angle rate of change module 102 may estimate the rate of change of the hitch angle 56 using the kinematic model and integrate the estimated rate of change with respect to a sample period associated with the estimated rate of change to obtain the estimated hitch angle rate of change. For example, the estimated hitch angle rate of change module 102 may estimate the rate of change of the hitch angle 56 using relationship (1): θ˙=VCltrsin(α−θprev)−ω(lhltrcosθprev+1) where θ̇ is the estimated rate of change of the trailer angle 56, θ prev is the previous hitch angle (as detected by the coupling 34 at T0), α is the mean of the first and second rear wheel steering angles 76 and 77, ω is the angular velocity of the vehicle 12, V c the speed of the vehicle is 12, l h the distance from the rear axle 22 of the vehicle 12 to the trailer coupling 34 of the vehicle 12 and l tr is the distance from the trailer coupling 34 of the vehicle 12 to the axle 68 of the trailer 14. The angular velocity of the vehicle 12 is in Fig. 3 is given at 82, the speed of vehicle 12 is in Fig. 3 is indicated at 86, the wheelbase of the vehicle 12 is in Fig. 3 is indicated at 88, the distance from the rear axle 22 of the vehicle 12 to the trailer coupling 34 of the vehicle 12 is in Fig. 3 is given at 90 and the distance from the trailer coupling 34 of the vehicle 12 to the axle 68 of the trailer 14 is in Fig. 3 at 92.

[0028] With continued reference to Fig. 2 to 4, the curvature prediction module 104 predicts a radius of curvature of the motion of the vehicle 12 and the trailer 14 based on the previous hitch angle (θ prev ) and a similar radius of curvature based on the predicted trailer angle 56 based on the trailer movement and the estimated rate of change of the trailer angle 56. Fig. For example, Figure 4 shows a first path 94 that represents a current path of the trailer 14 based on the previous hitch angle (θ prev) as sensed by the hitch 34. A second path 96 represents a predicted path of the trailer 14 based on the estimated rate of change of the hitch angle 56. Line 98 represents a radius of curvature of the first path 94, and line 99 represents a radius of curvature of the second path 96. The curvature prediction module 104 performs calculations to determine the second path 96. Calculations include various curvature dimensions of the vehicle 12 and the trailer 14 and various angles of the vehicle 12 and the trailer 14. In particular, the calculations determine a predicted curvature of the vehicle 12 and the trailer 14 at a selected distance (e.g., ten (10) feet) from the current location of the trailer 14 and the output generated by the module 102 for the estimated rate of change of the hitch angle, as shown in relationships (2) and (3): RB=(lh cos α+ltr cos(α−θprev)) / sin(α−θprev) RY=(lh cos α+ltr cos(α−θd)) / sin(α−θd) where R B the constant curvature of the movement of the trailer 14 based on the previous trailer angle (θ prev ) is, as detected by the clutch 34, R Y is the constant curvature of the motion of the trailer 14 based on the output generated by the estimated rate of change of the hitch angle module 102, θ d is the predicted hitch angle (i.e., the integration of the estimated rate of change of hitch angle 56 generated by module 102 at a selected distance from the current location of trailer 14), α is the rear wheel steering angle 76, l h the distance from the rear axle 22 of the vehicle 12 to the trailer coupling 34 of the vehicle 12 and l tr the distance from the trailer coupling 34 of the vehicle 12 to the axle 68 of the trailer 14.

[0029] The example implementation of the VCM 44, which is shown in Fig. 2, further includes a driver assistance module 106, a steering control module 108, and a braking control module 110. The driver assistance module 106 controls the user interface device 42 based on the corrected hitch angle to assist the driver in driving the vehicle 12. The driver assistance module 106 may control the user interface device 42 to display a trailer back-up trajectory, display a combined rear view image, provide side-slip detection and / or trailer sway alarms. For example, the driver assistance module 106 may control the user interface device 42 to vibrate the steering wheel 46 and / or the driver seat to warn the driver of a potential side-slip when the corrected hitch angle is greater than a predetermined angle.In another example, the driver assistance module 106 may control the user interface device 42 to generate a visible trailer rear trajectory that provides virtual lines drawn on a camera view to assist a driver in controlling the movement of the trailer 14 (discussed below). In another example, the driver assistance module 106 may control the user interface device 42 to generate a combined rear view image depicting an area behind the vehicle 12 when mitigating a disturbance caused by the trailer 14 (discussed below).

[0030] The steering control module 108 controls the active rear steering actuator 53 based on the estimated rate of change of the hitch angle to assist the driver by automatically steering the vehicle 12 (e.g., by steering the vehicle 12 independent of input from the driver, such as the steering wheel angle measured by the rear steering angle sensor). The steering control module 108 may control the active rear steering actuator 53 based on the estimated rate of change of the hitch angle for side-steering prevention (e.g., while the vehicle 12 is moving the trailer 14 backward) and obstacle avoidance (e.g., while the vehicle 12 is moving the trailer 14 forward). For example, the steering control module 108 may control the active rear steering actuator 53 to decrease the rate of change of the hitch angle 56 when the corrected hitch angle is greater than the predetermined angle.

[0031] The steering control module 108 may control the active rear steering actuator 53 to reduce the rate of change of the trailer angle by turning the left and right rear wheels 26 and 28 of the vehicle 12 to the left or right 56. For example, when the vehicle 12 and the trailer 14 are in Fig. 1 is reversing and the rate of change of the hitch angle 56 is greater than the predetermined angle, the steering control module 108 may command the active rear steering actuator 53 to turn at least the rear wheels 26 and 28 to the right. Turning the rear wheels 26 and 28 to the right (while the front wheels 24 simultaneously or additionally turn to the right) may significantly reduce the rate of change of the hitch angle 56, thereby preventing the vehicle 12 and trailer 14 from skidding.

[0032] With continued reference to Fig. 2, the brake control module 110 controls the friction brakes 30 of the vehicle 12 and / or the friction brakes 72 of the trailer 14 based on the corrected hitch angle to assist the driver by automatically braking the vehicle 12 and / or the trailer 14 (e.g., by braking the vehicle 12 and / or the trailer 14 regardless of driver input such as a brake pedal position). The brake control module 110 may control the friction brakes 30 and / or 72 based on the corrected hitch angle for side-steering control. For example, the steering control module 108 may apply the friction brakes 30 and / or 72 to decelerate the vehicle 12 when the corrected hitch angle is greater than the predetermined angle. The steering control module 108 and / or the brake control module 110 may be referred to as an actuator control module.

[0033] In Fig. 5, a method 500 for estimating the rate of change of the trailer angle 56 to assist in controlling a vehicle that includes active rear steering (ARS) capabilities is shown. As discussed above, ARS is a chassis technology that provides the ability to turn the rear wheels of the vehicle 12 to impart greater stability and control under certain driving conditions and implementations.

[0034] The method 500, or portions thereof, may be implemented in a computer program product (e.g., VCM 44, etc.) embodied in a computer-readable medium and comprising instructions usable by one or more processors of one or more computers of one or more systems to cause the one or more systems to implement one or more of the method steps. The computer program product may include one or more software programs consisting of program instructions in source code, object code, executable code, or other formats; one or more firmware programs or hardware description language (HDL) files; and any program-related data. The data may include data structures, lookup tables, or data in any other suitable format. The program instructions may include program modules, routines, programs, objects, components, and / or the like.The computer program can be executed on one computer or on several computers in communication with each other.

[0035] The one or more programs may be embodied on computer-readable media, which may be non-transitory and may include one or more storage devices, articles of manufacture, or the like. Example computer-readable media include computer system memory, e.g., RAM (Random Access Memory), ROM (Read Only Memory); semiconductor memory, e.g., EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), Flash memory; magnetic or optical disks or tapes; and / or the like. The computer-readable medium may also include, for example, computer-to-computer connections when data is transferred or delivered over a network or other communications link (either wired, wireless, or a combination thereof). Any one or more combinations of the above examples are also included within the scope of computer-readable media.Therefore, it should be understood that the method may be performed, at least in part, by any electronic articles and / or devices capable of executing instructions corresponding to one or more steps of the disclosed method.

[0036] The method 200 begins at 501, in which a vehicle operator (vehicle driver) begins operating the vehicle 12 in reverse, and consequently places the vehicle 12 in reverse gear. In step 510, the rear steering sensor embedded in the active rear steering actuator 53 measures the angular position of the right and left rear wheels 26 and 28. In step 520, the wheel speed sensor 36 measures the wheel speed of the left or right rear wheel 26 or 28. At 530, the estimated hitch angle rate of change module 102 estimates the hitch angle rate of change 56 based on the rear wheel steering angle and the vehicle speed using the kinematic model of the vehicle 12 and the trailer 14. For example, the estimated hitch angle rate of change module 102 may estimate the hitch angle rate of change 56 using relationship (1) discussed above.

[0037] In step 540, the driver assistance module 106 controls the user interface device 42 to generate a visible trailer return trajectory view 602 that provides virtual lines drawn on a camera view to assist a driver in controlling the movement of the trailer 14. With additional reference to Fig. 6, for example, the driver assistance module 110 generates a view 600 comprising a first pair of guide lines 604 superimposed over the image area captured by the camera 40, wherein the first pair of guide lines 604 represents a current path of the trailer based on the previous hitch angle (θ prev). A second pair of guide lines 606 is also shown and represents a predicted path of the trailer based on a predicted path of the trailer 14 via the estimated rate of change of the hitch angle 56. The first pair of guide lines 604 and the second pair of guide lines 606 may be visually distinguished on the display by suitable marking such as different colors, different formats (dashed versus solid), etc. Also shown for illustrative purposes is a selected location or destination 608 for the trailer that is reachable by a selected path that is not currently aligned with the current path. A distance d from the rear of the trailer is shown for illustrative purposes. The first pair of guide lines 604 and the second pair of guide lines 606 are separated by an amount Δ at distance d.Typically, as the trailer moves backward (decreasing d), the first pair of guide lines 604 (i.e., the current path) adjusts to align with the second pair of guide lines 606 (i.e., the predicted path).

[0038] Using the steering wheel 46 and the guide lines on the user interface device 42, the vehicle operator (vehicle user) can change the rear wheel steering angle (α) of the vehicle 12 to adjust the path 606 of the second pair of guide lines (i.e., turn the left and right rear wheels 26 and 28 to adjust the path 606 of the second pair of guide lines). Consequently, this causes the first pair of guide lines 604 to change due to its tendency to align with the second pair of guide lines 606 during reverse movement. The driver changes (via the steering wheel) the second pair of guide lines 606 to move the first pair of guide lines 604 (which continuously aligns along the second pair of guide lines 606) along the selected or desired path for the trailer 14 to reach the selected destination 608.The first pair of guide lines 604 and the second pair of guide lines 606 therefore inform the vehicle operator (vehicle driver) of a selected steering angle that will reverse the trailer 14 to the desired location or destination 608. If the vehicle operator turns the steering wheel 46 too hard, so that the rear wheel steering angle (α) of the vehicle 12 becomes greater than a predetermined reference hitch angle (θ). ref ), the driver assistance module 106 may also provide one or more trailer sway alarms (discussed above). The predetermined reference hitch angle (θ ref ) may be one that has a high potential to cause the trailer 14 to break away (e.g. θ ref > 70 degrees).

[0039] Additionally or alternatively, in this step, the driver assistance module 106 controls the user interface device 42 to generate a combined rearview image (not shown) obtained using a camera mounted on the rear end 16 of the vehicle 12 (not shown), in addition to the camera 40, which is combined with various graphics to depict an area behind the vehicle 12 while mitigating interference caused by the trailer 14 (commonly known as an invisible trailering technique). A first image may be obtained, for example, by a rear-facing vehicle camera to show the front end 62 of the trailer 14. A second image may also be obtained by the camera 40 of the trailer 14. Moreover, the second image is overlaid on the first image in a predetermined image overlay region.To cause the second image to fit within this overlay region, the second image may be repositioned and / or resized on the first image in an image overlay position using a variety of known techniques so as not to produce a distorted appearance of the combined rear view image. The overlay region may be based on the estimated rate of change of the hitch angle 56 output from the estimated rate of change of the hitch angle module 102, as well as trailer dimension information (e.g., trailer length). For example, the overlay region may be articulated within the first image in such a way that the overlay region corresponds to the articulation of the second image (the area behind the trailer 14).Once the first and second images are stitched together, various graphics can be overlaid onto the combined image to highlight any distinctive road features such as lane markings and road edges.

[0040] In an optional step 550, if the vehicle operator (vehicle driver) wishes to enable the vehicle 12 to autonomously navigate itself toward the destination 608, the steering control module 108 controls the active rear steering actuator 53 based on the estimated rate of change of the hitch angle 56 to assist the vehicle operator (vehicle driver) by automatically steering the vehicle 12. For example, if the estimated rate of change of the hitch angle 56 is determined to be greater than the predetermined reference hitch angle, the steering control module 108 may control the active rear steering actuator 53 based on the estimated rate of change of the hitch angle to prevent the trailer 14 from skidding.To prevent skidding and avoid obstacles, the steering control module 108 may further control the active rear steering actuator 53 to reduce the rate of change of the hitch angle 56 by turning the left and right rear wheels 26 and 28 of the vehicle 12 to the left or right (such that it is less than the predetermined reference hitch angle). The vehicle operator (vehicle driver) may trigger activation of the steering control module 108 via one or more virtual buttons provided via the user interface device 42. In an optional step 560, the brake control module 110 operates in conjunction with the steering control module 108 to control the friction brakes 30 of the vehicle 12 and / or the friction brakes 72 of the trailer 14 to assist the driver by automatically braking the vehicle 12 and / or the trailer 14 (e.g.,by braking the vehicle 12 and / or the trailer 14 independently of driver input such as brake pedal position). The brake control module 110 may control the friction brakes 30 and / or 72 based on the estimated rate of change of the hitch angle to prevent the trailer 14 from skidding. As follows, the brake control module 110 assists in controlling the vehicle 12 while performing the steering function of the steering control module 108. Method 500 ends at 502.

Claims

[1] System (10) which includes: a memory configured to include one or more executable instructions, and a processor configured to execute the executable instructions, wherein the executable instructions enable the processor to: estimates a rate of change of a hitch angle between a trailer (14) and a vehicle (12), the estimated rate of change of the hitch angle being based on a steering angle for a plurality of rear wheels (26, 28) of the vehicle (12) and the speed of the vehicle (12); characterized by , that the estimated rate of change of the trailer angle is based on the following relationship: θ˙=VCltrsin(α−θprev)−ω(lhltrcosθprev+1) where θ̇̇ is the rate of change of the estimated trailer angle, θ prev is a previous trailer angle, α is a rear wheel steering angle, ω is an angular velocity of the vehicle (12), V cthe speed of the vehicle (12) is l h a distance from a rear axle of the vehicle (12) to a trailer coupling of the vehicle (12) and l tr a distance from a trailer coupling of the vehicle (12) to an axle of the trailer (14). [2] System (10) according to claim 1, characterized by , that the executable instructions further enable the processor to: predicts a first radius of curvature of a movement of the vehicle (12) and the trailer (14) based on a previous hitch angle; and predicts a second radius of curvature of the movement of the vehicle (12) and the trailer (14) based on the estimated rate of change of the hitch angle. [3] System (10) according to claim 1, characterized by , that the executable instructions further enable the processor to: generates a visible trailer return trajectory view (602) based on the estimated rate of change of the hitch angle, wherein the trailer return trajectory (602) is configured to provide one or more virtual lines on a camera view to assist a driver in controlling the movement of the trailer (14). [4] System (10) according to claim 1, wherein the executable instructions further enable the processor to: controls an active rear steering actuator based on the estimated rate of change of the trailer angle to steer the vehicle (12) to assist a vehicle operator. [5] System (10) according to claim 4, characterized by , that the executable instructions further enable the processor to: controls one or more friction brakes (30) of the vehicle (12) and / or one or more friction brakes (72) of the trailer (14) based on the estimated rate of change of the hitch angle to assist in controlling an actuator of the active rear steering. [6] Procedure which includes: Estimating a rate of change of a hitch angle between a trailer (14) and a vehicle (12), wherein the estimated rate of change of the hitch angle is based on a steering angle for a plurality of rear wheels (26, 28) of the vehicle (12) and a speed of the vehicle (12); characterized by , that the estimated rate of change of the trailer angle is based on the following relationship: θ˙=VCltrsin(α−θprev)−ω(lhltrcosθprev+1) where θ̇̇ is the estimated rate of change of the trailer angle, θ previs a previous trailer angle, α is a rear wheel steering angle, ω is an angular velocity of the vehicle (12), V c the speed of the vehicle (12) is l h a distance from a rear axle of the vehicle (12) to a trailer coupling of the vehicle (12) and l tr a distance from a trailer coupling of the vehicle (12) to an axle of the trailer (14). [7] Method according to claim 6, characterized by that the procedure further comprises: Generating a visible trailer return trajectory view (602) based on the estimated rate of change of the hitch angle, wherein the trailer return trajectory (602) is configured to provide one or more virtual lines on a camera view to assist a driver in controlling the movement of the trailer (14). [8] Method according to claim 6, characterized by that the procedure further comprises: Controlling an active rear steering actuator based on the estimated rate of change of the trailer angle to steer the vehicle (12) to assist a vehicle operator.

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