Method for assisting in reversing tractor with trailer, computer program product and auxiliary reversing system

Abstract

The invention relates to a method for assisting a tractor with a trailer in reversing, which comprises the following steps: a steering decoupling step: enabling a steering wheel of the tractor and a wheel steering mechanism of the tractor to be separated from a coupling form when the tractor advances and to be in a decoupling state; in the receiving step, a steering wheel signal representing the current steering wheel rotation angle is received; and a solving step of solving a current expected included angle based on the received steering wheel signal according to a preset relationship between the steering wheel rotation angle and the expected included angle. The invention also relates to a corresponding computer program product and an auxiliary reversing system. The device has the advantages that the operation is simple through the steering wheel; the operation of a driver is visual without experience; by preferentially using rear wheel steering, the expected included angle can be efficiently achieved, and collision is avoided; the expected included angle can be quickly achieved through the steps of feedforward, feedback and weight determination.

Description

Technical Field

[0001] This application relates to a method for assisting a tractor-trailer in reversing, a computer program product, and a reversing assistance system. Background Technology

[0002] Many towing vehicles are now equipped with trailers. For example, family cars or SUVs sometimes have trailer jacks installed on the back, allowing the trailer to be attached to the towing vehicle when needed. For towing vehicles with trailers, reversing to move the trailer to the desired position is a challenge for most drivers, as it requires considerable experience. Summary of the Invention

[0003] The purpose of this application is to provide a method for assisting a trailer-trailer in reversing, so that the driver can easily reverse to the desired position without extensive experience.

[0004] According to a first aspect of this application, a method for assisting a tractor-trailer in reversing is provided, the method comprising at least the following steps:

[0005] The steering decoupling step involves decoupling the steering wheel of the tractor from the wheel steering mechanism of the tractor when the tractor is moving forward.

[0006] The receiving step, in the decoupled state, receives a steering wheel signal representing the current steering wheel rotation angle as input from the driver to the desired angle between the trailer and the tractor.

[0007] The calculation step involves determining the current desired angle based on the received steering wheel signal, according to a preset relationship between the steering wheel rotation angle and the desired angle.

[0008] "Decoupling state" is specifically understood as a state in which the rotation of the steering wheel no longer proportionally causes the steering action of the tractor's wheel steering mechanism as it does when the tractor is moving forward. In cases where the steering wheel and steering mechanism are mechanically coupled, decoupling state is specifically understood as the release of this mechanical coupling. In cases where the steering wheel and steering mechanism constitute a steer-by-wire system, decoupling state is specifically understood as the controller no longer linearly controlling the steering mechanism based on the steering wheel signal in the manner that the tractor is moving forward. When only the front wheels of the tractor are steering, the wheel steering mechanism is a front-wheel steering mechanism; however, when both the front and rear wheels of the tractor are steering, the wheel steering mechanism can involve both the front-wheel steering mechanism and / or the rear-wheel steering mechanism.

[0009] According to a second aspect of this application, a computer program product is provided, comprising computer program instructions that, when executed by one or more processors, enable the processors to perform the aforementioned method for assisting a trailer-trailer in reversing.

[0010] According to a third aspect of this application, a reversing assistance system is provided, the reversing assistance system including a control device that performs the aforementioned method for assisting a tractor-trailer to reverse.

[0011] At least in some embodiments, the positive effects of this application are as follows: the driver can accurately and conveniently input the desired angle between the trailer and the tractor through the steering wheel; it can be easily achieved through existing steer-by-wire systems; by prioritizing rear-wheel steering, the desired angle can be achieved more efficiently, and lateral displacement of the tractor caused by front-wheel steering can be avoided, thereby avoiding unnecessary collisions; and the desired angle can be achieved quickly through feedforward, feedback, and weight determination steps. Attached Figure Description

[0012] The principles, features, and advantages of this application will be better understood below with reference to the accompanying drawings. The drawings include:

[0013] Figure 1 An example of several steps of the method of this application for assisting a tractor-trailer in reversing is illustrated schematically.

[0014] Figure 2 An example of a tractor unit with a trailer is shown schematically.

[0015] Figure 3 An example of a graph used to explain the weight determination steps is shown schematically.

[0016] Figure 4 This illustration shows an example of the components of a reversing assistance system.

[0017] Figure 5 An example of several steps of the method of this application is illustrated schematically. Detailed Implementation

[0018] To make the technical problems to be solved, the technical solutions, and the beneficial technical effects of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and several exemplary embodiments. It should be understood that the specific embodiments described herein are only for explaining this application and are not intended to limit the scope of protection of this application.

[0019] Figure 1An example of several steps of the method of this application for assisting a tractor 1 with a trailer 2 in reversing is illustrated schematically.

[0020] Figure 2 An example of a tractor 1 with a trailer 2 is shown schematically.

[0021] like Figure 1 As shown, the method includes at least the following steps:

[0022] Steering decoupling step 61, in which the steering wheel 41 of the tractor 1 (see...) is decoupled. Figure 4 The wheel steering mechanism of the tractor 1 is decoupled from the coupling form when the tractor 1 is moving forward and is in a decoupled state.

[0023] In receiving step 62, in the decoupled state, a steering wheel signal S representing the current steering wheel rotation angle is received as the driver's input to the desired angle between the trailer 2 and the tractor 1.

[0024] Step 63 involves determining the current desired angle ψ based on the received steering wheel signal S, according to a preset relationship between the steering wheel rotation angle and the desired angle. tar .

[0025] In this way, on the one hand, the driver can directly input the desired angle between the trailer 2 and the tractor 1 without having extensive reversing experience; on the other hand, the steering wheel 41 allows the driver to accurately and conveniently input the desired angle.

[0026] According to an exemplary embodiment of this application, such as Figure 2 As shown, the tractor 1 is a four-wheeled tractor, and the trailer 2 is a two-wheeled trailer. The tractor 1 and the trailer 2 are hinged, particularly by means of a hinge ball at hinge point 10. However, the tractor 1 and the trailer 2 may also have other numbers of wheels.

[0027] exist Figure 2 In, for example, the rotation center MP of trailer 2 t The rotation center MP of the tractor 1 c Overlap (represented here by the symbol &.). See also Figure 2 The rotation center MP of tractor 1 c The front wheel steering angle δ of tractor 1 fa The perpendicular line and the rear wheel steering angle δ ra The intersection of the perpendiculars of the two points, the center of rotation of trailer 2, MP t The point where the axis of the trailer axle intersects the line connecting the hinge point 10 and the rotation center MP of the tractor 1 is the point where the axis of the axle intersects the line connecting the hinge point 10 and the tractor 1. cThe connections are well known in the prior art and will not be described further here. At the center of rotation MP of trailer 2... t The rotation center MP of the tractor 1 c When they coincide, a steady-state reversing condition is formed.

[0028] According to an exemplary embodiment of this application, referring to Figure 1 In step 63, the current desired angle ψ is calculated using the following formula. tar

[0029] ψ tar =θ drv / θ max *ψ max

[0030] Where, θ drv θ is the steering wheel rotation angle represented by the received steering wheel signal S. max ψ is the maximum value of the preset effective steering wheel rotation angle range. max This refers to the pre-determined maximum controllable angle between the tractor unit 1 and the trailer unit 2. For example, if the preset effective steering wheel rotation angle range is -90° to +90°, and the pre-determined maximum controllable angle is 40°, then if the current steering wheel rotation angle is +45°, the desired angle can be calculated as +20° using the above formula. The sign of the steering wheel rotation angle can be based on the steering wheel's zero position, and the sign of the desired angle can be relative to the centerline of the tractor unit 1. The correspondence between the sign of the steering wheel rotation angle and the sign of the desired angle is particularly determined by the driver's subconscious reversing instincts. For example... Figure 2 As shown, when the driver turns the steering wheel to the right, with right as the positive direction, the current steering wheel rotation angle is positive. At this time, according to the subconscious reversing, it can be determined that the driver wants the trailer 2 to deviate to the right relative to the tractor 1 while reversing. Therefore, the desired angle is positive with the centerline of the tractor 1 on the right.

[0031] In particular, the maximum controllable included angle ψ is obtained based on the following formula. max

[0032]

[0033] R is obtained based on the following formula. v R c R t

[0034] R v =L v / tanδ fa_max +tan δ ra_max

[0035]

[0036]

[0037] Among them, L v L is the distance between the front and rear axles of tractor 1. c L is the distance from the rear axle of tractor 1 to the hinge point 10 between tractor 1 and trailer 2. t δ is the distance from the hinge point 10 to the trailer wheel axle. fa_max δ is the maximum steering angle of the front wheel of tractor 1. ra_max R is the maximum steering angle of the rear wheels of tractor 1. t R represents the minimum turning radius that trailer 2 can achieve when simultaneously performing a steering process using the front and rear wheels of tractor 1. v This indicates the distance MP from the centerline of tractor 1 to the center of rotation of tractor 1 under the corresponding conditions. c The spacing, R c Indicates the rotation center MP of trailer 2 under the corresponding conditions. t The distance to the hinge point 10 between the tractor 1 and the trailer 2.

[0038] Here, the maximum controllable angle, especially at the rotation center MP of trailer 2, is... t The rotation center MP of the tractor 1 c It was obtained under the condition of overlap.

[0039] Given the tractor 1 and trailer 2, parameter L v L c L t δ fa_max δ ra_max It is definite, so R v R c R t ψ max It is also certain. Therefore, ψ max It can be predetermined, without needing to be determined in step 63.

[0040] According to an exemplary embodiment of this application, such as Figure 1 As shown, the method includes a turning angle determination step 64, in which the wheels of the tractor 1 are determined to achieve the current desired angle ψ. tar The target turning angle δ should be adopted. tar Here, step 64, determining the turning angle, is indicated by a dashed box. Specifically, when both the front and rear wheels of the tractor 1 are capable of steering, the target turning angle δ... tar Involves the target steering angle δ of the front wheels tar_fa and rear wheel target angle δ tar_ra When only the front wheels of tractor 1 can steer, the target turning angle δ tarOnly involves the target steering angle δ of the front wheels tar_fa .

[0041] According to an exemplary embodiment of this application, when both the front and rear wheels of the tractor 1 are capable of steering, the following principle is followed in the angle determination step 64: to achieve the current desired included angle ψ tar When the maximum steering angle δ of the rear wheels of tractor 1 is reached ra_max Previously, only the rear wheels of tractor 1 were steered, until the maximum rear wheel turning angle δ was reached. ra_max Then, make the rear wheels take the maximum rear wheel steering angle δ. ra_max It also causes the front wheels of the tractor 1 to turn.

[0042] According to an exemplary embodiment of this application, such as Figure 1 As shown, the angle determination step 64 includes a feedforward determination step 641, a feedback determination step 642, and a weight determination step 643. In the feedforward determination step 641, the position of the wheels of the tractor 1 at the rotation center MP of the tractor 1 is calculated. c The rotation center MP of trailer 2 t To achieve the desired angle ψ under the condition of overlap tar The angle to be adopted should be used as the feedforward part of the target angle δ. ff_tar In the feedback determination step 642, based on the current expected included angle ψ tar The angle ψ with the current actual angle act The difference is used to calculate the steering angle that the wheels of tractor 1 should take to eliminate the difference, which is then used as the target steering angle feedback component δ. fb_tar In the weight determination step 643, based on the current expected angle ψ tar The angle ψ with the current actual angle act The difference and / or based on the current actual included angle ψ act Determine the target rotation angle feedforward component δ ff_tar Feedforward weighting coefficient C ff and target angle feedback part δ fb_tar Feedback weight coefficient C fb The target turning angle δ can be obtained using the following formula. tar

[0043] δ tar =δ ff_tar *C ff +δ fb_tar *C fb

[0044] Among them, C ff With C fb The relationship is especially for C fb =1-C ff However, it is also possible to imagine C ff With C fbOther relationships.

[0045] Feedforward is especially used at the rotation center MP of the tractor 1. c The rotation center MP of trailer 2 t Under the condition of coincidence (i.e., under the condition of steady-state reversing), achieve the current desired angle ψ. tar The expected angle ψ is not considered here. tar The angle ψ with the current actual angle act The difference is therefore called "feedforward". Feedforward can be understood in particular as being used for "fine-tuning". Feedback, on the other hand, mainly considers the current desired angle ψ. tar The angle ψ with the current actual angle act The difference is intended to quickly reduce the current actual included angle ψ. act Approximately the current expected angle ψ tar Feedback, in particular, can be understood as "coarse-tuning".

[0046] Correspondingly, especially for the front and rear wheels, the target steering angle feedforward portion δ of the front wheels is calculated using the following formula. ff_tar_fa and the front wheel target angle feedback part δ fb_tar_fa The target steering angle δ of the front wheel is obtained. tar_fa

[0047] δ tar_fa =δ ff_tar_fa *C ff +δ fb_tar_fa *C fb

[0048] Furthermore, the target steering angle feedforward component δ of the rear wheel is calculated according to the following formula. ff_tar_ra and the rear wheel target angle feedback part δ fb_tar_ra The target steering angle δ of the rear wheel is obtained. tar_ra

[0049] δ tar_ra =δ ff_tar_ra *C ff +δ fb_tar_ra *C fb .

[0050] According to an exemplary embodiment of this application, the feedforward determination step 641 includes an arbitration step, in which the angle ψ between the trailer 2 and the currently desired angle is determined. tar The corresponding target turning radius R t_tar The minimum turning radius R that trailer 2 can achieve when only the rear wheels of tractor 1 are turned. t_r Comparison. Alternatively, in the arbitration procedure, the target rear wheel angle corresponding to the current desired angle may be compared with the maximum rear wheel angle when only the rear wheels of the tractor 1 are steered.

[0051] According to an exemplary embodiment of this application, the current desired included angle ψ is calculated using the following formula. tar Find the target turning radius R of trailer 2. t_tar

[0052]

[0053] Furthermore, the minimum turning radius R that trailer 2 can achieve when only the rear wheels of tractor 1 are turned is obtained based on the following formula. t_r That is, the maximum steering angle δ of the rear wheel ra_max Minimum turning radius achievable under certain conditions

[0054]

[0055]

[0056] R v_r =L v / tan δ ra_max

[0057] Similarly, given tractor 1 and trailer 2, parameter L v L c L t δ ra_max It is definite, so R v_r R cr R t_r It is also certain. Therefore, R t_r It can be predetermined.

[0058] According to an exemplary embodiment of this application, if |R t_r |<R t_tar The arbitration concluded that the desired angle ψ could be achieved by steering only the rear wheels of tractor 1. tar Furthermore, and in particular, in the feedforward determination step 641, the feedforward portion δ of the rear wheel target steering angle of the tractor 1 is calculated according to the following formula. ff_tar_ra

[0059] δ ff_tar_ra =tan -1 L v / (tan(π-ψ tar )·L v +L c +L t / cosψ tar )

[0060] The front wheel target steering angle feedforward part δ of tractor 1 ff_tar_fa =0;

[0061] If |R t_r|>R t_tar The arbitration concludes that the desired angle ψ cannot be achieved by only steering the rear wheels of tractor 1. tar Furthermore, and in particular, in the feedforward determination step 641, the rear wheel target steering angle feedforward portion δ ff_tar_ra Determined as δ ff_tar_ra =δ ra_max And calculate the feedforward portion δ of the target steering angle of the front wheel of tractor 1 according to the following formula. ff_tar_f_fa

[0062] δ ff_tar_f_fa =tan -1 (L v -R v_tar ·tan δ ra_max / R v_tar )

[0063]

[0064] The calculations in step 641, which determine the feedforward, are also based on steady-state reversing conditions.

[0065] Figure 3 An example of a graph used to explain step 643 of the weight determination is shown schematically.

[0066] According to an exemplary embodiment of this application, if the currently desired included angle ψ tar The angle ψ with the current actual angle act The difference Δψ=ψ tar -ψ act The absolute value of |Δψ| = |ψ tar -ψ act |Greater than the first threshold ψ1, especially if the current expected angle ψ tar The angle ψ with the current actual angle act Positive and negative are opposite, or in other words, the expected angle ψ tar The angle ψ with the current actual angle act If the components are located on either side of the central axis of the tractor 1, then in the weight determination step 643, they are determined to be in the feedback-dominant stage P1, and the feedback weight coefficient C is set. fb It is determined to be greater than the feedforward weight coefficient C. ff In particular, the feedback weighting coefficient C fb =1 and the feedforward weight coefficient C ff =0, and especially in the feedback determination step 642, the target angle feedback part δ fb_tar The maximum turning angle of the wheels of tractor 1 in the direction suitable for reducing the turning radius of tractor 1 is determined.

[0067] If the absolute value of the difference Δψ, |Δψ|, is less than the first threshold ψ1 but greater than the second threshold ψ2, then it is determined as transition stage P2 in weight determination step 643, and the feedforward weight coefficient C increases as the difference Δψ decreases. ff And reduce the feedback weight coefficient C fb Furthermore, especially in the feedback determination step 642, the target angle feedback part δ is included. fb_tar Determined as δ fb_tar =Δψ*k, where k is a preset coefficient;

[0068] If the absolute value of the difference Δψ, |Δψ|, is less than the second threshold ψ2, then in the weight determination step 643, it is determined to be the feedforward dominant stage P3, and the feedforward weight coefficient C is set. ff It is determined to be greater than the feedback weight coefficient C. fb In particular, the feedforward weighting coefficient C ff ≥0.8 and feedback weighting coefficient C fb ≤0.2, specifically, the feedforward weighting coefficient C ff The value is 0.8 or 0.9, and the feedback weighting coefficient C is... fb Accordingly, it is 0.2 or 0.1, and especially in the feedback determination step 642, the target angle feedback portion δ is included. fb_tar Determined as δ fb_tar =Δψ*m, where m is a preset coefficient.

[0069] In particular, k and m can be equal or different.

[0070] Here, at the current expected angle ψ tar The angle ψ with the current actual angle act When on the same side of the centerline of the tractor 1, the feedback determination step 642 is specifically based on the following logic:

[0071] If the current desired angle ψ tar Less than the current actual included angle ψ act Therefore, it is necessary to reduce the turning radius of tractor 1;

[0072] If the current desired angle ψ tar Greater than the current actual included angle ψ act Therefore, it is necessary to increase the turning radius of the tractor 1.

[0073] According to an exemplary embodiment of this application, when both the front and rear wheels of the tractor 1 are capable of steering, the following principle is followed in the feedback determination step 642: if the obtained target rear wheel steering angle δ tar_ra Less than the maximum steering angle δ of the rear wheel ra_max Then the rear wheel target steering angle feedback section δ will be used first. fb_tar_ra To eliminate the current expected angle ψ tarThe angle ψ with the current actual angle act The difference and the front wheel target steering angle feedback part δ fb_tar_fa =0; if the obtained rear wheel target steering angle δ tar_ra Exceeding the maximum steering angle δ of the rear wheel ra_max Then the target steering angle δ of the rear wheel tar_ra Determined as δ tar_ra =δ ra_max Furthermore, based on this, the front wheel target steering angle feedback component δ is determined. fb_tar_fa .

[0074] According to an exemplary embodiment of this application, such as Figure 1 As shown, the method includes execution step 65, in which the wheels of the tractor 1 are turned in accordance with the determined target turning angle. Execution step 65 affects the current actual included angle ψ. act This effect is illustrated here with a dashed line.

[0075] Figure 4 This illustration shows an example of the components of an auxiliary reversing system.

[0076] like Figure 4 As shown, the reversing assistance system includes a control device 3. The control device 3 executes the method of this application for assisting a tractor 1 with a trailer 2 in reversing.

[0077] According to an exemplary embodiment of this application, such as Figure 4 As shown, the auxiliary reversing system includes a front wheel steering device 4. The front wheel steering device 4 includes a steering wheel 41 and a front wheel steering mechanism 42. The control device 3, for example, can decouple the front wheel steering mechanism 42 from the steering wheel 41 and can control the front wheel steering mechanism 42 in the decoupled state. The front wheel steering device 4 is, for example, a steer-by-wire device.

[0078] According to an exemplary embodiment of this application, such as Figure 4 As shown, the reversing assistance system includes a rear-wheel steering mechanism 5. The control device 3 can control the rear-wheel steering mechanism 5. The rear-wheel steering mechanism 5 is controlled by the control device 3 only during the reversing assistance process and when the front-wheel steering mechanism 42 is decoupled from the steering wheel 41.

[0079] Furthermore, it is conceivable that the reversing assistance system includes an activation switch on the tractor 1 for activating the reversing assistance function, such as a physical switch or a virtual switch that can be displayed on an interactive interface.

[0080] Figure 5 An example of several steps of the method of this application is illustrated schematically.

[0081] According to an exemplary embodiment of this application, such as Figure 5 As shown, the method includes a check step 601, in which the start conditions for assisted reversing are checked, and the start conditions include at least one of the following:

[0082] Trailer 2 has been correctly attached to tractor 1;

[0083] The reverse assist function is activated;

[0084] Tractor 1 is in reverse gear;

[0085] Steering wheel 41 return to center;

[0086] Tractor 1 is operating normally;

[0087] The attitude of tractor 1 is normal;

[0088] Driver in position;

[0089] Tractor 1 is stationary.

[0090] In particular, the actual assisted reversing process is only initiated when all these starting conditions are met, thereby ensuring reversing safety. It can be envisioned that steering decoupling step 61 is only permitted if all these starting conditions are satisfied.

[0091] According to an exemplary embodiment of this application, such as Figure 5 As shown, the method includes a setting step 602, in which the effective rotation angle range of the steering wheel of the tractor 1 is set. This effective rotation angle range is smaller than the actual permissible rotation angle range of the steering wheel 41, specifically -90° to +90°. The actual permissible rotation angle range of the steering wheel 41 is generally -270° to +270°. By setting the effective rotation angle range in this way, the driver's workload can be effectively reduced.

[0092] Additionally, it is conceivable that in setting step 602, additional mechanical restrictions are imposed on the permissible rotation range of the steering wheel 41, for example, by mechanically restricting the steering wheel 41 to only be able to rotate from -90° to +90°, or, when the driver rotates the steering wheel 41 to a rotation angle exceeding the effective rotation angle range, the rotation angle is equated to the maximum value of the effective rotation angle range. For example, when the effective rotation angle range is from -90° to +90°, even if the actual rotation angle of the steering wheel is 120°, the received steering wheel signal is only considered to represent a 90° steering wheel rotation angle.

[0093] For example, the setting step 602 can be performed after the decoupling step 61, and the receiving step 62 can be performed after the setting step 602.

[0094] According to an exemplary embodiment of this application, such as Figure 5 As shown, the method includes a display step 603, in which the display device of the tractor 1 displays the calculated current desired angle, and in particular, additionally displays the expected reversing trajectory calculated based on the current desired angle. Thus, the driver can conveniently adjust the steering wheel 41's rotation angle according to the display device's display until the calculated current desired angle and / or expected reversing trajectory displayed on the display device matches the driver's expectations.

[0095] According to an exemplary embodiment of this application, such as Figure 5 As shown, the method includes an exit calibration step 66. In this exit calibration step 66, when exiting the assisted reversing, the rear wheels of the tractor 1 are positioned in the straight-line direction, the turning angle of the front wheels of the tractor 1 corresponds to the steering wheel rotation angle as when the tractor 1 is moving forward, and the steering wheel 41 of the tractor 1 is coupled to the wheel steering mechanism in the same coupling manner as when the tractor 1 is moving forward. This allows the tractor 1 and the trailer 2 to drive normally after the assisted reversing ends.

[0096] According to an exemplary embodiment of this application, the method includes a monitoring step in which, during assisted reversing, the reversing speed of the tractor 1 is monitored to see if it exceeds a speed limit and / or an emergency stop request is received. If the speed limit is exceeded or an emergency stop request is received, the braking device of the tractor 1 is activated and / or assisted reversing is disengaged. Additional monitoring may also be performed during the monitoring step, such as monitoring whether the trailer 2 is still properly suspended, the gear position of the tractor 1, the driver's status, etc. The monitored items may also refer to suitable items in the activation conditions. If a risky situation is detected, assisted reversing can be disengaged and the user notified visually and audibly. Exemplarily, the monitoring step continues to be performed after the steering decoupling step 61.

[0097] The following example illustrates the working steps of the reverse assist function:

[0098] - The driver engages reverse gear and requests activation of the reverse assist function via the start switch;

[0099] - Reversing assist system check

[0100] • Check whether the operating status of tractor 1 is normal, such as whether the system power is on and whether the ESP system reports an error.

[0101] • Whether the driver is in the seat can be checked, for example, by a camera or a weight sensor on the seat;

[0102] • Check whether trailer 2 has been correctly attached to tractor 1, for example by using a dedicated sensor, and whether the driver has confirmed through the user interface that trailer 2 has been correctly attached to tractor 1.

[0103] • Check whether the attitude of the tractor 1 is normal, such as checking the forward and backward tilt and the left and right tilt of the tractor 1. In other words, check whether the tractor 1 is on flat ground.

[0104] • Check if tractor 1 is stationary;

[0105] -If all checks pass, the reverse assist system requires the driver to straighten the wheels by using the steering wheel 41, or alternatively or additionally, may require the driver to move forward to straighten the trailer 2 relative to the tractor 1 and then require the driver to engage reverse gear.

[0106] - The reverse assist system requires the driver to press the start switch again to confirm that the reverse assist system has been officially activated;

[0107] - The reverse assist system decouples the steering wheel 41 from the front wheel steering mechanism 42;

[0108] - The driver turns the steering wheel 41 and observes the display device to adjust the steering wheel 41 according to the displayed angle and / or reversing trajectory to make it conform to the actual expectation. At the same time, the driver controls the reversing speed through the accelerator and brake. The auxiliary reversing system automatically controls the turning angle of the wheels of the tractor 1 based on the current expected angle obtained from the steering wheel turning angle. During this process, the auxiliary reversing system also monitors whether there is a situation that requires disengaging the auxiliary reversing function.

[0109] - If the reverse assist ends, or the reverse assist is interrupted due to an emergency, or the driver switches to drive, the reverse assist system makes the turning angle of the front wheels of the tractor 1 correspond to the steering wheel turning angle in the same way as when driving forward. For example, it makes the front wheels and steering wheel 41 return to center. In addition, if there is rear wheel steering, it also makes the rear wheels return to center, and it makes the steering wheel 41 and the front wheel steering mechanism 42 coupled in the same way as when driving forward.

[0110] In this context, the steering wheel rotation angle includes both the magnitude and direction of the rotation of the steering wheel 41, i.e., it is signified. Specifically, the steering wheel rotation angle refers to the angle of rotation of the steering wheel 41 relative to its zero-position when the wheels of the tractor 1 are straightened.

[0111] All concepts related to the included angle refer to the angle between trailer 2 and tractor 1. Here, the included angle specifically refers to the angle opening away from tractor 1 and is the angle between the centerline of tractor 1 and the centerline of trailer 2. The centerline is understood as the longitudinal centerline. Similar to the steering wheel rotation angle, the current desired angle and the current actual angle include both the magnitude and direction of the angle.

[0112] In describing representative embodiments, the specification may have presented the method as a specific sequence of steps. However, the method should not be limited to the specific order of steps described herein, to the extent that the method does not depend on the specific order of steps described herein. Other sequences of steps are also possible, as will be understood by those skilled in the art. Therefore, the specific order of steps set forth in the specification should not be construed as limiting, but merely as an example.

[0113] In this context, even if not explicitly stated, all features can be considered as standalone and can be combined with any other features in any way, without being limited to the combinations described in the application.

[0114] Although specific embodiments of this application are described in detail herein, they are given for illustrative purposes only and should not be construed as limiting the scope of this application. Various substitutions, modifications, and alterations can be conceived without departing from the spirit and scope of this application.

[0115] List of reference numerals

[0116] 1 Tractor

[0117] 10 Hinge points

[0118] 2 trailers

[0119] 3. Control device

[0120] 4. Front wheel steering system

[0121] 41 Steering Wheel

[0122] 42 Front wheel steering mechanism

[0123] 5. Rear wheel steering mechanism

[0124] 601 Inspection Procedure

[0125] 61. Steering Decoupling Steps

[0126] 602 Setup Steps

[0127] 62 Receiving Steps

[0128] 63. Steps to obtain

[0129] 603 Display Steps

[0130] 64. Steps for determining the angle

[0131] 641 Feedforward Determination Steps

[0132] 642 Feedback Confirmation Steps

[0133] 643 Weight Determination Steps

[0134] 65. Execution Steps

[0135] 66. Calibration steps upon exit

Claims

1. A method for assisting a tractor (1) with a trailer (2) in reversing, characterized in that, The method includes at least the following steps: Steering decoupling step (61): In the steering decoupling step (61), the steering wheel (41) of the tractor (1) is decoupled from the wheel steering mechanism of the tractor (1) when the tractor (1) is moving forward and is in a decoupled state. In the receiving step (62), in the decoupled state, a steering wheel signal representing the current steering wheel rotation angle is received as the driver's input of the desired angle between the trailer (2) and the tractor (1); In step (63), the current desired angle is determined based on the received steering wheel signal according to the preset relationship between the steering wheel rotation angle and the desired angle.

2. The method according to claim 1, characterized in that, The method includes a turning angle determination step (64), in which the wheels of the tractor (1) are determined to achieve the current desired angle ψ. tar The target turning angle δ should be adopted. tar ; When both the front and rear wheels of the tractor (1) are capable of steering, the target turning angle δ tar Involves the target steering angle δ of the front wheels tar_fa and rear wheel target angle δ tar_ra When only the front wheels of the tractor (1) can turn, the target turning angle δ tar Only involves the target steering angle δ of the front wheels tar_fa .

3. The method according to claim 2, characterized in that, The method includes at least one of the following features: When both the front and rear wheels of the tractor (1) are capable of steering, the following principles are followed in the angle determination step (64): to achieve the current desired angle ψ tar When the maximum steering angle δ of the rear wheel of the tractor (1) is reached ra_max Previously, only the rear wheels of the tractor (1) were steered, until the maximum rear wheel turning angle δ was reached. ra_max Then, make the rear wheels take the maximum rear wheel steering angle δ. ra_max And additionally, it steers the front wheels of the tractor (1); The angle determination step (64) includes a feedforward determination step (641), a feedback determination step (642), and a weight determination step (643). In the feedforward determination step (641), the weights are calculated to achieve the desired angle ψ when the rotation center of the tractor (1) coincides with the rotation center of the trailer (2). tar The angle to be adopted should be used as the feedforward part of the target angle δ. ff_tar In the feedback determination step (642), based on the current expected angle ψ tar The angle ψ with the current actual angle act The difference is calculated, and the steering angle that the wheels of the tractor (1) should take to eliminate the difference is used as the target steering angle feedback part δ. fb_tar In the weight determination step (643), based on the current expected angle ψ tar The angle ψ with the current actual angle act The difference and / or based on the current actual included angle ψ act Determine the target rotation angle feedforward component δ ff_tar Feedforward weighting coefficient C ff and target angle feedback part δ fb_tar Feedback weight coefficient C fb The target turning angle δ can be obtained using the following formula. tar d tar =d ff_tar *C ff +d fb_tar *C fb Among them, C ff With C fb The relationship is especially for C fb =1-C ff , Furthermore, specifically for the front and rear wheels, the feedforward portion δ of the target steering angle of the front wheel is calculated using the following formula. ff_tar_fa and the front wheel target angle feedback part δ fb_tar_fa The target steering angle δ of the front wheel is obtained. tar_fa d tar_fa =d ff_tar_fa *C ff +d fb_tar_fa *C fb Furthermore, the target steering angle feedforward component δ of the rear wheel is calculated according to the following formula. ff_tar_ra and the rear wheel target angle feedback part δ fb_tar_ra The target steering angle δ of the rear wheel is obtained. tar_ra d tar_ra =d ff_tar_ra *C ff +d fb_tar_ra *C fb 。 4. The method according to any one of the preceding claims, characterized in that, In step (63), the current desired angle ψ is calculated using the following formula. tar ψ tar =(θ drv / i max )*ψ max Where, θ drv θ is the steering wheel rotation angle represented by the received steering wheel signal. max ψ is the maximum value of the preset effective steering wheel rotation angle range. max The maximum controllable angle between the tractor (1) and the trailer (2) is predetermined. In particular, the maximum controllable included angle ψ is obtained based on the following formula. max R is obtained based on the following formula. v R c R t R v =L v / (tanδ fa_max +tanδ ra_max ) Among them, L v L is the distance between the front and rear axles of the tractor (1). c L is the distance from the rear axle of the tractor (1) to the hinge point (10) between the tractor (1) and the trailer (2). t δ is the distance from the hinge point (10) to the trailer wheel axle. fa_max δ is the maximum steering angle of the front wheel of the tractor (1). ra_max R is the maximum steering angle of the rear wheels of the tractor (1). t R represents the minimum turning radius that the trailer (2) can achieve when simultaneously performing a steering process through the front and rear wheels of the tractor (1). v R represents the distance from the centerline of the tractor (1) to the center of rotation of the tractor (1) under the corresponding conditions. c This indicates the distance from the rotation center of the trailer (2) to the hinge point (10) under the corresponding conditions.

5. The method according to claim 3, characterized in that, The feedforward determination step (641) includes an arbitration step, in which the angle ψ between the trailer (2) and the current desired angle is determined. tar The corresponding target turning radius R t_tar The minimum turning radius R that the trailer (2) can achieve when only the rear wheels of the tractor (1) are turned. t_r Compare: In particular, based on the current expected angle ψ according to the following formula tar Find the target turning radius of trailer (2) And R is derived based on the following formula. t_r R v_r =L v / tanδ ra_max If |R t_r | <R t_tar The arbitration concluded that the desired angle ψ could be achieved by steering only the rear wheels of the tractor (1). tar Furthermore, and in particular, in the feedforward determination step (641), the feedforward portion δ of the rear wheel target steering angle of the tractor (1) is calculated according to the following formula. ff_tar_ra δ ff_tar_ra =tan -1 (L v / (tan(π-ψ tar )·(L v +L c +L t / Cosψ tar ))) The front wheel target steering angle feedforward portion δ of the tractor (1) ff_tar_fa =0; If |R t_r |>R t_tar The arbitration concludes that the desired angle ψ cannot be achieved by only steering the rear wheels of the tractor (1). tar Furthermore, and in particular, in the feedforward determination step (641), the rear wheel target steering angle feedforward portion δ ff_tar_ra Determined as δ ff_tar_ra =δ ra_max And the feedforward portion δ of the front wheel target steering angle of the tractor (1) is obtained according to the following formula. ff_tar_fa δ ff_tar_fa =tan -1 ((L v -R v_tar ·tanδ ra_max ) / R v_tar ) 6. The method according to claim 3, characterized in that, If the current desired angle ψ tar The angle ψ with the current actual angle act The difference Δψ=ψ tar -ψ act The absolute value |Δψ| is greater than the first threshold, especially if the current expected angle ψ tar The angle ψ with the current actual angle act If the positive and negative values ​​are opposite, then in the weight determination step (643), it is determined to be the feedback-dominated stage and the feedback weight coefficient C is set. fb It is determined to be greater than the feedforward weight coefficient C. ff In particular, the feedback weighting coefficient C fb =1 and the feedforward weight coefficient C ff =0, and especially in the feedback determination step (642), the target angle feedback part δ is given. fb_tar The maximum turning angle of the wheels of the tractor (1) in the direction suitable for reducing the turning radius of the tractor (1); If the absolute value of the difference Δψ, |Δψ|, is less than the first threshold but greater than the second threshold, then it is determined to be a transition stage in the weight determination step (643), and the feedforward weight coefficient C increases as the difference Δψ decreases. ff And reduce the feedback weight coefficient C fb And especially in the feedback determination step (642), the target angle feedback part δ is included. fb_tar Determined as δ fb_tar =Δψ*k, where k is a preset coefficient; If the absolute value of the difference Δψ, |Δψ|, is less than the second threshold, then in the weight determination step (643), it is determined to be the feedforward dominant stage and the feedforward weight coefficient C is set. ff It is determined to be greater than the feedback weight coefficient C. fb In particular, the feedforward weighting coefficient C ff ≥0.8 and feedback weighting coefficient C fb ≤0.2, specifically, the feedforward weighting coefficient C ff The value is 0.8 or 0.9, and the feedback weighting coefficient C is... fb Accordingly, it is 0.2 or 0.1, and especially in the feedback determination step (642), the target angle feedback portion δ is included. fb_tar Determined as δ fb_tar =Δψ*m, where m is a preset coefficient. In particular, k and m can be equal or different.

7. The method according to claim 6, characterized in that, When both the front and rear wheels of the tractor (1) are capable of steering, the following principle is followed in the feedback determination step (642): if the obtained target rear wheel steering angle δ tar_ra Less than the maximum steering angle δ of the rear wheel ra_max Then the rear wheel target steering angle feedback section δ will be used first. fb_tar_ra To eliminate the current expected angle ψ tar The angle ψ with the current actual angle act The difference and the front wheel target steering angle feedback part δ fb_tar_fa =0; if the obtained rear wheel target steering angle δ tar_ra Exceeding the maximum steering angle δ of the rear wheel ra_max Then the target steering angle δ of the rear wheel tar_ra Determined as δ tar_ra =δ ra_max Furthermore, based on this, the front wheel target steering angle feedback component δ is determined. fb_tar_fa .

8. The method according to any one of claims 2 to 7, characterized in that, The method includes an execution step (65) in which the wheels of the tractor (1) are turned in accordance with the determined target turning angle.

9. The method according to any one of the preceding claims, characterized in that, The method includes a checking step (601), in which the starting conditions for assisted reversing are checked, the starting conditions including at least one of the following: The trailer (2) has been correctly attached to the tractor (1); The reverse assist function is activated; The tractor (1) is in reverse gear; Steering wheel (41) returned to center; The tractor (1) is operating normally; The tractor (1) is in normal posture; Driver in position; The tractor (1) is stationary.

10. The method according to any one of the preceding claims, characterized in that, The method includes a setting step (602), in which an effective rotation angle range of the steering wheel of the tractor (1) is set, the effective rotation angle range being less than the actual allowable rotation angle range of the steering wheel (41), the effective rotation angle range being particularly -90° to +90°.

11. The method according to any one of the preceding claims, characterized in that, The method includes at least one of the following steps: In the display step (603), the display device of the tractor (1) is made to display the current desired angle obtained, and in particular, the display device of the tractor (1) is made to display the expected reversing trajectory based on the current desired angle. In the exit calibration step (66), when exiting the auxiliary reversing, the rear wheels of the tractor (1) are positioned in the straight direction, the turning angle of the front wheels of the tractor (1) corresponds to the steering wheel rotation angle as when the tractor (1) is moving forward, and the steering wheel (41) of the tractor (1) is coupled to the wheel steering mechanism in the same coupling form as when the tractor (1) is moving forward. The monitoring step involves monitoring whether the reversing speed of the tractor (1) exceeds the speed limit and / or monitoring whether an emergency stop request is received during assisted reversing. If the speed limit is exceeded or an emergency stop request is received, the braking device of the tractor (1) is activated and / or assisted reversing is discontinued.

12. The method according to any one of the preceding claims, characterized in that, The tractor (1) is a four-wheeled tractor, and the trailer (2) is a two-wheeled trailer. The tractor (1) and the trailer (2) are articulated together.

13. A computer program product, characterized in that, It includes computer program instructions that, when executed by one or more processors, enable the processors to perform a method for assisting a tractor (1) with a trailer (2) to reverse according to any one of claims 1 to 12.

14. A reversing assistance system, characterized in that, The auxiliary reversing system includes a control device (3) that performs a method for assisting a tractor (1) with a trailer (2) in reversing according to any one of claims 1 to 12.

15. The auxiliary reversing system according to claim 14, characterized in that, The auxiliary reversing system includes a front wheel steering device (4), which includes a steering wheel (41) and a front wheel steering mechanism (42). The control device (3) can decouple the front wheel steering mechanism (42) from the steering wheel (41) and can control the front wheel steering mechanism (42) in the decoupled state. The front wheel steering device (4) is a steer-by-wire device; The auxiliary reversing system also includes a rear wheel steering mechanism (5), and the control device (3) can control the rear wheel steering mechanism (5).

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