RU2694645C1 - Mobile system for assistance to driver of vehicle with trailer at rear manoeuvring - Google Patents

Abstract

FIELD: motor industry; control systems.SUBSTANCE: group of inventions relates to a method of controlling a car with a reverse trailer. Mobile system for assistance to driver of car with trailer at manoeuvre by reverse gear includes sensor of coupling angle, sensor of steering wheel steering angle, data input module, controller and man-machine interface. Hitch angle sensor determines angle between longitudinal axes of vehicle and trailer. Controller comprises adjuster angle control which forms vehicle control law with possibility of preventing situations when desirable value of coupling angle exceeds folding angle. Driver steering wheel angle sensor and coupling angle sensor are self-contained, easy-detachable and have wireless communication channel for transmitting measured data.EFFECT: easier control of vehicle with trailer at backward movement.2 cl, 3 dwg

Description

The present invention relates to mechanical engineering, in particular to a system and method of driving a car with a trailer in reverse. The invention allows to facilitate driving with a trailer when driving back, initially not equipped with a standard system of assistance to maneuver with a trailer in reverse. The proposed system does not require intervention in the staffing system of the car and implies minimal costs for its implementation.

The proposed system includes: sensors for the deflection angle of the steering wheel (rudder) of the driver and the hitch angle of the trailer with the vehicle (deviations of the longitudinal axis of the trailer from the longitudinal axis of the vehicle) with a wireless data transmission channel and a mobile device such as a smartphone or tablet used to enter control system parameters specified values of the hitch angle, limiting signals, calculating the angle of rotation of the driver’s steering wheel and issuing commands to the driver (voice and / or in the form of a dynamic image) for their implementation.

The method of operating the system, which is low cost due to the ease of installation of the system on the car. The method includes successive steps in which, using a mobile device, the control system is initialized by inputting the system parameters, the required hitch angle is set when reversing maneuvering; make signal constraints to ensure system health; form commands to the driver, subject to execution, to achieve the specified value of the hitch angle.

The technical field to which the invention relates.

The alleged invention relates to a system and method of assisting a driver of a car not originally equipped with a reversing maneuver assistance system with a trailer, which is easy to install on a car and has a low implementation cost.

The level of technology

Reverse parking with a trailer can cause difficulties for both novice drivers and experienced drivers. A survey of drivers who have a trailer, showed that more than 70% of them can not park in reverse with a trailer. The peculiarity of this movement is that, moving backwards, it is necessary to compensate for small deviations of the trailer from straight-line movement by turning the steering wheel in the opposite direction. Inaccurate driver control can lead to the folding system (a large value of the angle of the hitch), to withdraw from this position can only be driven forward.

In order to assist the driver in driving with the trailer in reverse, the driver assistance system must take into account the driver’s intentions, analyze the current value of the hitch angle and the driver’s steering wheel angle and generate driving tips to the driver so that the trailer moves steadily in a given direction, eliminating the possibility folding hitch "car-trailer".

Known close to the invention in general characteristics and the achieved technical result analogues:

1. System and method of assistance to the driver of a vehicle with a trailer, patent RU 2574042, 10/31/2014, IPC B60R 1/00, B62D 13/06, B62D 15/02, G01C 21/20. An assistance system is proposed for placing a tag on a trailer designed to read its position through a video system of a car and to fulfill the task of driving a car with a trailer when moving backwards. In this case, as an option, it is proposed to use a mobile device (smartphone, tablet, etc.) to implement assistance in setting the label and setting up the video system.

The disadvantage in the key of the proposed invention is that the mobile device is not used for the current driving with a trailer while maneuvering backwards.

2. System and method of assistance when driving a vehicle in reverse with a trailer, patent RU 2627219 С2, 07.17.2015, IPC B60W 30/00. The reverse assistance system with a trailer for a vehicle contains a trailer having a braking system, a steering input device and a controller. The input device for steering commands is used to set the desired curvature of the trajectory of the trailer. The controller generates a command to automatically deflect the steering wheels of the vehicle and a command to activate the trailer brake system in order to achieve the desired curvature of the trailer path.

The prototype of the proposed invention: Assistance when reversing with a trailer, patent RU 2608786 C2, 04.17.2015, IPC B62D 1/24, B62D 13/06, B60W 30/00. It proposes the structure of the driver assistance system, which includes the following components: hitch angle sensors, deflection angle of the steering wheels of the vehicle and speed; module for inputting the required curvature of the trailer; a controller containing a curvature regulator and a hitch angle regulator; the device of the automatic drive of steering wheels of the car; man-machine interface. The driver, before maneuvering backwards, must enter the kinematic parameters of the vehicle-trailer object and set the required curvature value of the trailer path. Next, the driver is invited to control only the speed and as you move back to specify the specified curvature. At the same time, the curvature regulator, based on the analytical dependence, generates the required hitch angle value by a given curvature value. This signal is limited by the folding angle (to eliminate the possibility of folding the vehicle-trailer object), and is then monitored in a closed loop, organized by the hitch angle control. The output signal of this regulator is fed to the automatic device to drive the steering wheels of the car. The latter, practicing the incoming signal, deflects the steering wheels of the car and ensures the movement of the trailer with a given curvature.

The disadvantages of the second analogue and prototype is that:

- the installation of such systems is carried out at the vehicle manufacturer or at a specialized technical service center with the introduction of regular vehicle control systems, so there is no possibility of mobile reinstallation of the system from one vehicle to another;

- Mandatory availability of a standard video system and other special equipment;

- The high cost of such driver assistance systems.

The task of the claimed invention is the creation of such a system of assistance to driving a car with a trailer when maneuvering in reverse, which does not require intervention in the vehicle’s regular systems, will be inexpensive, easy to install, and mobile to reinstall to another car.

DISCLOSURE OF INVENTION

The task is solved by the fact that in the proposed system autonomous, compact, inexpensive sensors are used to measure the driver’s steering wheel (rudder) angle and the trailer hitch angle of the car, which are easily installed and removed from the car, and a mobile device is used for control or tablet) with preinstalled specialized software. Communication between the specified equipment is made over a wireless channel, such as Bluetooth. Before driving, the driver, using a mobile device, sets the parameters of the control system, a given hitch angle. The mobile device limits the signals to ensure the health of the system and generates commands to control signals from these sensors in order to achieve the specified value of the hitch angle. Driving is carried out by the driver for these commands (voice and / or in the form of a dynamic image) by deflecting the steering wheel.

Summary of figures

FIG. 1 shows the main kinematic relations of the control object “car-trailer” (top view).

FIG. 2 shows the structure of the driver assistance device.

FIG. 3 shows a variant of a man-machine interface implemented by a mobile device.

The implementation of the invention

FIG. 1 and in further discussion the following notation is used:

1 - the car; 2 - the longitudinal axis of the vehicle; 3 - car steering wheels; 4 - axis of the steering wheels of the car; 5 - axis of the rear axle of the car; 6 - axle trailer wheels; 7 - trailer; 8 - longitudinal axis of the trailer; 9 - trailer drawbar; 10 - hitch point of the drawbar of a trailer with a car;

обычно это ограничение не превышает величину 30°, поэтому примем: ϕ_max=30°; примем, что отклонение руля водителя и отклонение рулевых колес автомобиля связано соотношением:ϕ - the deflection angle of the steering wheels of the car 3, limited in the form of:

usually this limit does not exceed 30 °, therefore we will take: ϕ _max = 30 °; We assume that the driver’s steering deflection and the steering wheel's deflection are related by:

where φ _rudder - the driver's steering angle deviation, k _rudder - steering proportionality coefficient.

значение модуля угла сцепки, при превышении которого во время движения назад начинается непроизвольное увеличение

с невозможностью его компенсации из-за ограниченности ϕ называется углом складывания (θ_скл);θ is the hitch angle, or the deflection angle of the longitudinal axis of the trailer 8 from the longitudinal axis of the vehicle 2, we assume that

the magnitude of the hitch angle module, above which an involuntary increase begins while driving backwards

with the impossibility of its compensation due to the limitedness ϕ is called the folding angle (θ _skl );

_Authors Ψ, _{Ψ, etc.} - the yaw angle of the trailer 1 and 7 (respectively) of some direction, for example, a given (in the figure indicated by a vertical line);

V _{authors, etc.} V - velocity of the vehicle 1 and the trailer 7, respectively, the vehicle speed will be measured by the steering wheel 3 with the point of application at the center of the steering wheel rotation axis 4;

0 _avt , 0 _pr - centers (points) of rotation of the car 1 and trailer 7 on the turn, respectively;

R _CR - the radius of rotation of the trailer 7, measured along the axis of rotation of the wheels of the trailer 6 (effective axis for multi-axle trailer);

дополнительное требование к этим параметрам определится далее; a , b, c are the kinematic parameters of the control object “car-trailer” ( a , c are positive non-zero numbers), respectively: the wheelbase of the car, or the distance between the axes of rotation of the wheels of the car (4 and 5); the distance from the axis of the rear axle of the vehicle 5 to the hitch point 10; distance from the hitch point 10 of the tow bar of the trailer 9 to the axis of rotation of the wheels of the trailer 6 (effective axis for a multi-axle trailer); note that usually

an additional requirement for these parameters will be determined further;

- угловая скорость прицепа 7, появляющаяся из-за внешних неконтролируемых возмущений, природа возникновения которых указана выше; будем считать эту величину ограниченной.

- the angular velocity of the trailer 7, which appears due to external uncontrolled disturbances, the nature of which is indicated above; we will consider this quantity bounded.

To compose a mathematical description of the control object "car-trailer" the following assumptions are made:

- The car is moving at a relatively low speed;

- the effect of lateral compliance of tires, side skid of a car will not be taken into account;

- the movement dynamics is not taken into account, in particular, the obtained relations do not depend on accelerations.

It is known [Miroshnichenko A.N. Fundamentals of the theory of the car and the tractor. - Tomsk: Publishing House TGASU, 2014. - 490 s], that the angular velocity of the vehicle is determined by the dependence:

From FIG. 1 it is possible to determine that

соответствующий вращательному движению автомобиля. Исходя из этих векторов, определим линейную и угловую скорость прицепа. Путем проекции указанных векторов на продольную ось прицепа найдем скорость прицепа:When the vehicle is moving, two linear velocity vectors act on the hitch point 10: the vehicle's translational motion vector, corresponding to the vehicle's longitudinal speed (V _av cosϕ), and

corresponding to the rotational movement of the car. Based on these vectors, we determine the linear and angular velocity of the trailer. By projecting these vectors on the longitudinal axis of the trailer, we find the trailer speed:

по зависимости (2), найдемSubstituting here the expression for

according to (2), we find

перпендикулярным продольной оси прицепа (см. фиг. 1). Из кинематической схемы ясно, что при

The angular velocity of the trailer is determined by the linear velocity vector

perpendicular to the longitudinal axis of the trailer (see Fig. 1). From the kinematic scheme it is clear that with

Also making the substitution by (2), and taking into account the non-zero disturbing effect in the general case, we find:

то по зависимостям (2) и (5) несложно определить скорость изменения угла θ:Since from (3) it follows that

then using dependencies (2) and (5), it is easy to determine the rate of change of the angle θ:

Комбинируя по этой формуле синусы и косинусы по ϕ, можно найти:Dependence (6) can be rewritten differently, using the well-known equality [Bronshtein I.N., Semendyayev K.A. Handbook of mathematics for engineers and students of technical colleges. - M .: Science, Ch. ed. Phys.-Mat. lit., 1986. - 177 p.]:

Combining the sines and cosines of ϕ using this formula, one can find:

- положительный коэффициент усиления (утверждение о положительности легко установить из принятых условий);Where

- positive gain (the statement about the positivity is easy to establish from the accepted conditions);

- балансировочная зависимость угла рулевых колес автомобиля по углу θ; или значение ϕ такое, что если его зафиксировать, то при

текущее значение угла сцепки будет находиться в балансировочном положении:

или объект «автомобиль-прицеп» будет находиться в установившемся развороте, причем как при движении вперед, так и назад;

- balancing dependence of the angle of the steering wheels of the car on the angle θ; or the value of ϕ such that if you fix it, then

the current value of the hitch angle will be in the balancing position:

or the “car-trailer” object will be in a steady turn, both when moving forward and backward;

- параметр линеаризации функции ϕ_бал(θ) около точки θ=0;

- the parameter of linearization of the function ϕ _bal (θ) near the point θ = 0;

- производная функции ϕ_бал(θ) по своему аргументу.

- derivative of the function ϕ _bal (θ) in its argument.

We study the dynamics of changes in the angle θ in accordance with equality (7) when moving forward (V _auto > 0) and in the absence of external disturbance

To do this, we first consider the derivative of the function ϕ _bal (θ). From its value it can be seen that if the parameters a , b, c are all positive, then in the full range of change of the coupling angle λ (θ)> 0, i.e. the function ϕ _bal (θ) is increasing. If b is negative, then the specified property requires the condition

- максимально возможное значение модуля угла сцепки. Будем понимать условие (8) как дополнительное условие при отрицательном параметре b, которое считаем выполненным.Where

- the maximum possible value of the hitch angle module. We will understand condition (8) as an additional condition with a negative parameter b, which we consider to be fulfilled.

т.е. текущее положение рулевых колес автомобиля меньше, чем балансировочное значение, соответствующее текущему углу θ. Из зависимости (7) следует, что это порождает

т.е. уменьшение угла θ. А поскольку функция ϕ_бал(θ) возрастающая, то при этом будет уменьшаться и сам эта функция. Это будет продолжаться до тех пор, пока не наступит равенство ϕ=ϕ_бал(θ_бал).Next, we consider the case when the value of the angle of the steering wheels of the vehicle satisfies the conditions: ϕ _ball (θ)> ϕ = const,

those. the current position of the steering wheels of the car is less than the balancing value corresponding to the current angle θ. From dependence (7) it follows that this generates

those. decrease in angle θ. And since the function ϕ _bal (θ) is increasing, this function will also decrease. This will continue until equality ϕ = ϕ _bal (θ _bal ).

Similar arguments can be constructed for the case of ϕ _bal (θ) <ϕ≡const. This means that when driving forward (V _aut > 0) at a constant angle of rotation of the steering wheels θ → θ _ball ≡const, where the latter corresponds to the designated angle ϕ. That is, the movement of the system at the hitch angle is stable.

If the car moves backwards (V _aut <0) - it follows from similar reasonings that the system is precisely unstable, which explains all the problems of controlling such a movement. In this case, equation (7) will be:

Using an approach similar to that used in the derivation of equation (7), we can find the dependence inverse to ϕ _bal (θ):

Следует отметить, что при движении назад из-за неустойчивости системы этот угол имеет смысл угла складывания (θ_скл). Из (10) следует:Due to the increasing nature of the function ϕ _ball (θ), it follows that the maximum value of the angle of rotation of the steering wheels of the car (ϕ _max ) corresponds to the maximum modulus of the realizable balancing value of the hitch angle when moving forward

It should be noted that when moving back due to the instability of the system, this angle has the meaning of the folding angle (θ _sk ). From (10) it follows:

From the obtained relations (4) and (5), it is possible to find the curvature of the trailer’s path (κ) in the absence of external disturbance:

We also find the curvature of the trailer's path on a steady motion (turn) with a given value ϕ≡const ≠ 0 in the absence of an external disturbance. According to the above, this motion corresponds to θ = θ _bal = const by (10). The value of the curvature of the trailer for this case is also called the balancing value (κ _ball ). From (7) and (12), it is easy to find by direct substitution:

where the approximate dependence is obtained by linearizing about θ _bal = 0. This ratio shows that control by the signal θ _ball , if we take it for a given value, in approximately proportional dependence corresponds to control by the curvature of the trailer’s path, and therefore can replace the latter. This is implemented in the proposed invention.

определенная из (11) по линейному приближению, меньше точного значения.Equations (1) - (13) with accepted assumptions describe the kinematic and related dynamic relations of the control object “car-trailer”, which are necessary for the synthesis of the control law when reversing. Approximate equalities in relations (7), (10), (11), (13) by virtue of their definition accurately describe the corresponding dependences in the region of zero angles. With an increase in the modulus of angles, the error increases, but as the calculations for typical practical problems with the limitation ϕ _max = 30 ° show, the error does not exceed 10–15%. Also note that from the analysis of dependencies it follows that the value

determined from (11) by a linear approximation, less than the exact value.

Consider the options of the law of control. We assume that the parameters of the control object k _roll , a , b, c are given, and the specified value of the hitch angle (denoted as θ _back ) will be formed by the driver. To eliminate the possibility of folding the system, this signal is limited on the basis of (11) by the obvious inequality:

using a linear approximation, which means, as indicated, with a margin of 10-15%.

We propose a control law:

where k _ZU is a positive coefficient of the control law, which affects the speed of the transition process and the reduction of the influence of external disturbances; we assume that this parameter is inside the constraint:

This requirement follows from the subsequent reasoning.

Indeed, if the control law (15) is substituted into equation (9), we obtain a description of the dynamics of the coupling angle in a closed control system when moving backwards:

where approximate equality is given in linear approximation and dependencies in (7). The obvious requirement of stability and proportionality of control in the absence of a perturbation here is that the modulus of the sine argument does not exceed π / 2. Hence the upper limit (16).

Считая сигнал θ_зад постоянным, из точного равенства (17) несложно найти при назначенных ограничениях, что θ→θ_зад≡const. Это в свою очередь приводит по (1) и (15) ϕ→ϕ_бал(θ_зад)≡const. Налицо устойчивое поведение объекта управления, в частности, устойчивый поворот. Причем, сравнивая приблизительную часть (17) с уравнением динамики при движении вперед (7), можно видеть, что при k_ЗУ=1 динамика движения объекта «автомобиль-прицеп» при движении назад приблизительно такая-же, что и при движении вперед с ϕ=ϕ_бал(θ_зад)=const. Если k_ЗУ увеличить, то увеличится и скорость переходного процесса.Consider the case of the absence of external disturbances.

Assuming constant signal θ _rear, from the exact equation (17) it is easy to find at a designated limitations that θ → θ _backside ≡const. This in turn results from (1) and (15) ϕ → ϕ _bal (θ _ass ) ≡const. There is a stable behavior of the control object, in particular, a steady turn. Moreover, comparing the approximate part (17) with the equation of dynamics when moving forward (7), it can be seen that at k _ZU = 1, the movement dynamics of the “car-trailer” object when moving backward is approximately the same as when moving forward with ϕ = ϕ _bal (θ _ass ) = const. If k _{memory is} increased, then the speed of the transition process will increase.

При выходе угла поворота рулевых колес на свой конструктивный максимум будет просто ограничиваться скорость переходного процесса и, соответственно, затягиваться переходный процесс (по сравнению с «безлимитным» управлением).Such reasoning will be fair in the absence of external disturbance, even if the control synthesized from (15) goes into the constraint:

When the angle of rotation of the steering wheels at its constructive maximum will simply be limited by the speed of the transition process and, accordingly, the transition process is delayed (compared to the "unlimited" control).

Thus, the control law (15) when the vehicle-trailer object moves back under the specified conditions provides the same stable system behavior as when moving forward.

то на установившемся режиме (когда

) при линейных приближениях установившееся значение угла сцепки (θ_уст) выражается как:If an external disturbance acts on the trailer

then at steady state (when

) for linear approximations, the steady-state value of the hitch angle (θ _mouth ) is expressed as:

Since θ of the _set ≠ θ _ass , the other motion parameters will not be as expected. But from equality (18) it can be seen that by choosing k _ZU > 1, the influence of an external perturbation can be weakened.

Due to the forced inaccuracy of control under the influence of an external disturbance, the control law itself can be simplified: instead of (15), taking into account (7), we can write:

It differs from the law (15) only in the approximate setting of the function ϕ _ball (θ), consider what it gives. It can be rewritten as

- новое заданное значение угла сцепки, смещенное из-за неточности назначения ϕ_бал(θ). Здесь по аналогичным рассуждениям следует, что

но при увеличении параметра k_ЗУ указанная неточность уменьшается.Where

- the new setpoint of the hitch angle, offset due to the inaccuracy of the assignment ϕ _ball (θ). Here, according to similar reasoning, it follows that

but as the _memory parameter increases, the indicated inaccuracy decreases.

Modeling a control system with a control law (19) indicate its fairness. It is used in the proposed invention.

FIG. 2 shows the structure of the driver assistance device.

The driver’s steering wheel (rudder) sensor 11 and the hitch sensor of a trailer with a car 12 are fixed by the driver before starting to maneuver back with a trailer on the steering wheel and hitch, respectively, using quick-fastening systems (magnets, hooks, adhesive tape, etc.) and turn on . The sensors 11 and 12 transmit measurement signals wirelessly to the mobile device 13.

Sensors 11 and 12 can be constructed in various ways. The main criteria are: autonomy, wireless communication channel with a mobile device, compactness, easily detachability, low cost and an error of at least 1 degree.

An embodiment of the steering wheel angle sensor 11 may be based on the MPU6050 micromechanical sensor [MPU-6000 / MPU-6050 Product Specification. InvenSense, 2013, 54 p. Website: www.invensense.com], which is a three-axis angular velocity sensor (gyroscope) and a three-axis accelerometer. Since the axis of rotation of the steering wheel of modern cars is deflected from the vertical axis, it is possible using a complementary filter based on indications of the angular velocity and acceleration to build an autonomous, sufficiently accurate steering angle sensor. Similar solutions are used in modern gadgets. In addition, the sensor has a microcontroller for data processing, a wireless data channel and batteries.

A variant of the hitch angle sensor 12 can be a standalone sensor with a microcontroller, a wireless data channel and batteries, in which an optical encoder, a rotary potentiometer, etc. is used as a sensitive element. The deviation angle of the longitudinal axes is transmitted to the sensitive element car and trailer - hitch angle (see Fig. 2).

The mobile device 13 is installed at a place convenient for observation by the driver (dashboard, holder, etc.) and its specialized software is initialized. First, the control system parameters are entered or corrected (if necessary) to the mobile device: k _rudder , ϕ _max , a , b, c, k _charger . Further, also using the mobile device 13, a predetermined value of the hitch angle is entered (θ _rear ). The mobile device 13 limits the signals θ _back and k of the _charger by dependencies (14), (11), (7), (16) and forms the required deflection angle of the driver’s steering wheel according to (19). In addition, comparing the current angle of the driver’s steering wheel with the desired value, the mobile device 13 issues commands (voice and / or in the form of a dynamic image) to the driver for correcting this angle. The driver controls the vehicle speed independently. Also during maneuvering, it is possible to adjust the angle θ _back .

FIG. 3 shows a variant of the man-machine interface implemented by the mobile device 13 in the form of the program “Assistant”. The interface is implemented through several pages to configure and initialize the entire system, set the desired hitch angle and control the vehicle by commands from a mobile device (some of them are shown in Fig. 3). Page 14 demonstrates the procedure for entering a specified hitch angle by moving a trailer image on an interactive monitor. Pages 15 and 16 show the procedures for issuing commands to the driver for adjusting the steering wheel position and the current position of the trailer relative to a given one.

Claims (2)

1. Mobile assistance system for the driver of a car with a trailer when maneuvering in reverse, including: a hitch angle sensor, which determines the angle between the longitudinal axes of the car and the trailer; data entry module; a controller that contains in its composition a hitch angle regulator, which forms the law of driving with the possibility of preventing situations when the desired hitch angle exceeds the folding angle; human-machine interface, characterized in that the system uses the sensor of the angle of rotation of the driver's steering wheel; this sensor and the hitch angle sensor are autonomous, easily removable and have a wireless communication channel for transmitting the measured data; the data entry module, the controller and the human-machine interface are combined in a mobile device with special software that is used to set the parameters of the control system, the required hitch angle, limit the signals, receive information from the sensors over the wireless channel, process them and issue commands to the driver to control steering wheel to provide a specified hitch angle value. 2. A method of operating a mobile assistance system to a driver of a car with a trailer when maneuvering in reverse, characterized in that: the installation of the system on the vehicle is carried out by the driver himself and does not require large expenditures due to the lack of communication of the system with the standard equipment of the vehicle; Before the target use of the system, the parameters of the control system are entered via a mobile device; required by the conditions of maneuvering the value of the coupling angle and the gain of the control law, which changes the speed of the transition process, its accuracy and the effects of uncontrolled disturbing effects; limit the set value of the hitch angle to eliminate folding of the system, the gain of the control law and generate, via a mobile device, commands to the driver to control the steering wheel to reach the specified value of the hitch angle.

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