Method for estimating a maximum safe articulation angle to be used in reversing of a vehicle combination

Abstract

The disclosure relates to a method for estimating a maximum safe articulation angle (lim) to be used in reversing of a vehicle combination (1) comprising a towing vehicle (10) and at least one trailer (20), said method comprising: S1) providing a preset maximum safe articulation angle (lim) for the towing vehicle (10) or the vehicle combination (1), S2) receiving a signal being indicative of an articulation angle () of the vehicle combination (1) during forward driving of the vehicle combination (1), and S3) updating the maximum safe articulation angle (lim) when the articulation angle () of the vehicle combination (1) during forward driving is larger than the preset maximum safe articulation angle (lim). The disclosure also relates to a method for reversing a vehicle combination (10), to a control unit (11), to a towing vehicle (10), to a computer program and to a computer readable medium.

Claims

1. A method for reversing a vehicle combination comprising a towing vehicle and at least one trailer, the method comprising: reversing the vehicle combination, determining, by the control unit, whether a jack-knifing condition is about to occur by comparing a predicted future estimate of the articulation angle with a maximum safe articulation angle by: providing, at the control unit, a preset maximum safe articulation angle for the towing vehicle or the vehicle combination, receiving, by the control unit, a signal being indicative of an articulation angle of the vehicle combination during forward driving of the vehicle combination, and updating, by the control unit, the maximum safe articulation angle when the articulation angle of the vehicle combination during forward driving is larger than the preset maximum safe articulation angle, updating, by the control unit, the maximum safe articulation angle upon determination that a jack-knifing condition has occurred, whereby the updated maximum safe articulation angle corresponds to an articulation angle which occurred prior to the determined jack-knifing condition, and upon determination that the jack-knifing condition is about to occur, initiating, by the control unit, a braking action for the vehicle combination.

2. The method of claim 1, wherein the signal being indicative of the articulation angle is continuously or intermittently recorded during forward driving.

3. The method of claim 1, wherein the jack-knifing condition is determined by receiving a signal that indicates that at least one of the following events has occurred: an emergency call from the vehicle combination has been issued, an airbag of the towing vehicle has been deployed, a yaw, pitch or roll rate for the towing vehicle or the at least one trailer has exceeded a preset threshold value, a longitudinal or lateral acceleration for the towing vehicle or the at least one trailer has exceeded a preset threshold value, a force in a trailer coupling has exceeded a preset threshold value, a speed reduction of the towing vehicle or the vehicle combination has exceeded a preset threshold value, a value being indicative of a second time derivative of the articulation angle has exceeded a preset threshold value.

4. The method of claim 1, wherein the predicted future estimate of the articulation angle is derived from the current articulation angle and a first order time derivative of the current articulation angle.

5. The method of claim 1, wherein the predicted future estimate of the articulation angle is derived from the current articulation angle and a second order time derivative of the current articulation angle.

6. The method of claim 1, wherein the braking action is initiated, by the control unit, when the following condition is fulfilled: $.Math.+\frac{\stackrel{}{}{v}_x}{a_x}+{\stackrel{.Math.}{}\left(\frac{v_x}{a_x}\right)}^2/2.Math.>{}_{\lim }$ wherein v.sub.x corresponds to a reversing speed, a.sub.x corresponds to an achievable acceleration rate of the vehicle combination's braking system, corresponds to the articulation angle, {dot over ()} corresponds to the first order time derivative of the articulation angle, {umlaut over ()} corresponds to the second order time derivative of the articulation angle and .sub.lim corresponds to the maximum safe articulation angle.

7. The method of claim 1, further comprising issuing a warning signal, by the control unit, when the following condition is fulfilled: $.Math.+\stackrel{}{}\left(\frac{v_x}{a_x}+t_{\mathrm{reac}}\right)+{\stackrel{.Math.}{}\left(\frac{v_x}{a_x}+t_{\mathrm{reac}}\right)}^2/2.Math.>{}_{\lim }$ wherein v.sub.x corresponds to the reversing speed, a.sub.x corresponds to the achievable acceleration rate of the vehicle combination's braking system, corresponds to the articulation angle, corresponds to the first order time derivative of the articulation angle, corresponds to the second order time derivative of the articulation angle, t.sub.reac corresponds to an estimated driver reaction time from the warning signal is issued until a braking action has been initiated by the driver and .sub.lim corresponds to the maximum safe articulation angle.

8. The method of claim 1, wherein a value being indicative of a current steering wheel angle or a first derivative of the steering wheel angle is also used for determining if a jack-knifing condition is about to occur.

9. The method of claim 1, wherein at least one of a steering operation and a speed control operation of the vehicle combination during reversing is performed automatically without any direct human involvement.

10. A towing vehicle comprising a control unit configured to: determine whether a jack-knifing condition is about to occur by comparing a predicted future estimate of the articulation angle with a maximum safe articulation angle by: providing, at the control unit, a preset maximum safe articulation angle for the towing vehicle or the vehicle combination, receiving, by the control unit, a signal being indicative of an articulation angle of the vehicle combination during forward driving of the vehicle combination, and updating, by the control unit, the maximum safe articulation angle when the articulation angle of the vehicle combination during forward driving is larger than the preset maximum safe articulation angle, updating, by the control unit, the maximum safe articulation angle upon determination that a jack-knifing condition has occurred, whereby the updated maximum safe articulation angle corresponds to an articulation angle which occurred prior to the determined jack-knifing condition; wherein the control unit is further configured to, upon determination by the control unit that the jack-knifing condition is about to occur, initiate a braking action for the vehicle combination.

11. The towing vehicle according to claim 10, wherein the towing vehicle is a semi-autonomous or a fully autonomous vehicle.

12. The towing vehicle according to claim 10, comprising determining, by the control unit, an articulation angle between at least one of: the towing vehicle and a connected trailer; or two interconnected trailers.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

(2) In the drawings:

(3) FIG. 1 is showing a schematic illustration of a vehicle combination according to an example embodiment of the present invention,

(4) FIG. 2 is showing another schematic illustration of a vehicle combination according to an example embodiment of the present invention,

(5) FIG. 3 is showing another schematic illustration of a vehicle combination performing a reversing operation according to an example embodiment of the present invention,

(6) FIG. 4 is showing a principle illustration of a vehicle combination with an articulation angle according to an example embodiment of the present invention

(7) FIG. 5 is showing another principle illustration of a vehicle combination with a maximum safe articulation angle according to an example embodiment of the present invention,

(8) FIG. 6 shows a flowchart of a method according to an example embodiment of the first aspect of the invention, and

(9) FIG. 7 shows a flowchart of a method according to an example embodiment of the second aspect of the invention.

(10) The drawings show diagrammatic exemplifying embodiments of the present invention and are thus not necessarily drawn to scale. It shall be understood that the embodiments shown and described are exemplifying and that the invention is not limited to these embodiments. It shall also be noted that some details in the drawings may be exaggerated in order to better describe and illustrate the invention. Like reference characters refer to like elements throughout the description, unless expressed otherwise.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

(11) In FIG. 1, a schematic illustration of a vehicle combination 1, seen from above, according to an example embodiment of the present invention is depicted. The vehicle combination 1 comprises a towing vehicle 10, in this embodiment a towing truck, and a trailer 20 connected to the towing truck 10 via a coupling 21. The towing vehicle 10 and the trailer 20 are pivotably movable around the coupling 21, whereby an articulation angle of the vehicle combination 1 is the relative angle between the towing vehicle 10 and the trailer 20 in respect of the coupling 21. For more details about the articulation angle , see e.g. FIGS. 4 and 5. FIG. 1 illustrates when the vehicle combination 1 has reached a jack-knifing condition J, i.e. the towing vehicle 10 and the trailer 20 have reached such a large articulation angle that the two vehicles, truck/trailer, have hit into each other at the point J. In one example embodiment, a cabin of the truck 10 may have hit a side of the trailer 20. During a reversing operation of the vehicle combination 1, it may be important to avoid reaching the jack-knifing condition J. Thereby it may be required to provide a preset maximum safe articulation angle during the reversing operation. The preset angle may for example be provided to the driver, e.g. via a display, such that the driver during reversing checks that the maximum safe articulation angle is not reached by comparing said angle to the current articulation angle . Alternatively, or complementary, a driver assistance system may use the maximum safe articulation angle as input during the reversing operation for controlling the reversing operation. Hence, the driver assistance system may control the reversing operation such that the articulation angle will not exceed the maximum safe articulation angle .sub.lim. By the provision of the present invention, a more efficient reversing operation may be accomplished. More particularly, by receiving a signal being indicative of the articulation angle during forward driving of the vehicle combination 1, and updating the preset maximum safe articulation angle .sub.lim when the articulation angle of the vehicle combination 1 during forward driving is larger than the preset maximum safe articulation angle .sub.lim an even larger range of articulation angles may be allowed during a subsequent reversing operation without reaching the jack-knifing condition J.

(12) In FIG. 2, another schematic illustration of a vehicle combination 1 is depicted, showing another example of a jack-knifing condition J. Here, the towing truck 10 has hit into a trailer supporting leg 22 of the trailer 20.

(13) In FIG. 3, a schematic illustration of a vehicle combination 1 during a reversing operation can be seen. The towing truck 10 is reversing at a speed v.sub.x and is connected via a coupling 21 to a trailer 20. The reversing speed v.sub.x is this in this embodiment the speed of the towing truck 10, but may also be regarded as a translation speed of the articulation point 21, i.e. the coupling 21. Moreover, the towing truck may also brake, resulting in a braking acceleration a.sub.x, i.e. a deceleration, in an opposite direction to the truck speed v.sub.x. During the reversing operation, the vehicle combination 1 may advantageously make use of the updated maximum safe articulation angle .sub.lim in order to avoid a jack-knifing condition J and also to be able to in an efficient manner complete the reversing operation.

(14) A control unit 11 may be integrated in the towing truck 1, and being configured to perform the steps of the methods according to any one of the embodiments of the first and/or second aspects of the present invention. As already indicated hereinabove, the reversing operation may be performed semi-automatically or even fully automatically by e.g. the control unit 11 controlling any one of a steering operation and a vehicle speed v.sub.x. Alternatively, the reversing operation may also be performed manually by a driver of the vehicle 10.

(15) In FIGS. 4 and 5, the articulation angle and the maximum safe articulation angle .sub.lim of a vehicle combination 1 can be more clearly seen. The figures depict principle illustrations of a vehicle combination 1 which are connected and pivotably movable around the coupling 21, i.e. the articulation point. FIG. 4 may be regarded as a situation during reversing, such as can be seen in FIG. 3, where the vehicle combination 1 in a particular point in time during the reversing operation has a current articulation angle which is smaller than the maximum safe articulation angle .sub.lim as e.g. seen in FIG. 5. Thus, during the reversing operation as shown in FIG. 4, the articulation angle should not exceed the maximum safe articulation angle .sub.lim, and by the provision of the present invention, a larger range of articulation angles may be allowed during the reversing operation without reaching a jack-knifing condition J.

(16) The illustration in FIG. 5 may for example represent a situation during forward driving of the vehicle combination 1 where the maximum safe articulation angle .sub.lim is larger than a preset maximum safe articulation angle. Hence, a control unit 11 of the towing vehicle 1 may thereafter update the preset maximum safe articulation to the new and larger maximum safe articulation angle .sub.lim. The expression during forward driving as used herein means thus that the vehicle combination 1 or the towing vehicle 10 is having a speed v.sub.x which is larger than zero and in a forward direction in respect of the vehicle combination 1 or the towing vehicle 10. Hence, the vehicle combination 1 may be regarded as being in use or in operation.

(17) FIGS. 6 and 7 show flowcharts of example embodiments of the respective methods according to the first and second aspects of the invention.

(18) In step S1 in FIG. 6, a preset maximum safe articulation angle .sub.lim is provided for the towing vehicle 10 or the vehicle combination 1. Purely by way of example, the preset maximum safe articulation angle .sub.lim may be set to 100 degrees. In step S2, a signal is received being indicative of the articulation angle of the vehicle combination 1 during forward driving of the vehicle combination 1. For example, the vehicle combination 1 may be in use and driving forwardly at a shipping terminal area/logistics center area where it is required to make turns with large articulation angles (I). Hence, when it is recognized that the articulation angle is larger than the preset maximum safe articulation angle .sub.lim during the forward driving, the maximum safe articulation angle .sub.lim may be updated in step S3. Purely by way of example, it may be recognized that the articulation angle during forward driving is 105 degrees, i.e. larger than the preset maximum safe articulation angle of 100 degrees as mentioned hereinabove. Thereafter, a larger maximum safe articulation angle .sub.lim, i.e. 105 degrees, may be used as a limit during a subsequent reversing operation of the vehicle combination 1. As a complement, the maximum safe articulation angle .sub.lim may also be updated in step S4 when it has been determined that a jack-knifing condition J has occurred, whereby the updated maximum safe articulation angle .sub.lim corresponds to an articulation angle which occurred prior to the determined jack-knifing condition J. Purely by way of example, in relation to the aforementioned example, it may be determined that a jack-knifing condition occurs already at 98 degrees articulation angle , i.e. a value which is smaller than the preset maximum safe articulation angle of 100 degrees. Thereby, the maximum safe articulation angle .sub.lim may be updated to an angle being less than 98 degrees instead of 100 degrees, such as 97 degrees or less. The jack-knifing condition J may occur both at forward and rearward driving, and as already explained hereinabove, the jack-knifing condition may be determined by receiving a signal, to e.g. the control unit 11, that indicates that at least one of the following events has occurred: an emergency call from the vehicle combination has been issued, an airbag of the towing vehicle has been deployed, a yaw, pitch or roll rate for the towing vehicle or the at least one trailer has exceeded a preset threshold value, a longitudinal or lateral acceleration for the towing vehicle or the at least one trailer has exceeded a preset threshold value, a force in a trailer coupling has exceeded a preset threshold value, a speed reduction of the towing vehicle or the vehicle combination has exceeded a preset threshold value, a value being indicative of a second time derivative of the articulation angle has exceeded a preset threshold value.

(19) Vehicles may have integrated solutions for contacting emergency assistance (SOS). An emergency call (or message) can either be triggered by a button accessible to a driver of the vehicle 10 or automatically after e.g. air-bag deployment. The occurrence of an emergency call (or message) can be used as an indication of a possible jack-knifing condition J. It can thus be used to trigger a reset of .sub.lim to the value held prior to the event.

(20) Vehicles may also have collision detection sensors installed in various parts of the vehicle. The primary purpose is normally to trigger air-bag after collision. A collision with an obstacle can either be a consequence of a jack-knifing condition J or a jack-knifing condition J could occur after a collision. Irrespective of the case, the onset of a collision sensor could be used to reset .sub.lim to the value held prior to the event.

(21) A gyroscope may be used to measure either yaw, pitch or roll rate depending on its physical orientation on the vehicle 10. If either of these signals is observed to have a substantially larger absolute value than what is normal during normal driving it can indicate that a jack-knifing condition J has occurred. It can thus be used to trigger a reset of .sub.lim to the value held prior to the event. Abnormality may be defined with a preset limit value.

(22) An accelerometer may be used to measure either longitudinal or lateral acceleration depending on its physical orientation on the vehicle 10. If either of these signals is observed to have a substantially larger absolute value than what is normal during normal driving it can indicate that a jack-knifing condition J has occurred. It can thus be used to trigger a reset of .sub.lim to the value held prior to the event. Abnormality may be defined with a preset limit value.

(23) A strain gage, or other devices, may be used to measure forces in different directions in the trailer coupling 21. If either of these signals is observed to have a substantially larger absolute value than what is normal during normal driving it can indicate that a jack-knifing condition J has occurred. It may thus be used to trigger a reset of .sub.lim to the value held prior to the event. Abnormality may be defined with a preset limit value.

(24) Wheel speed sensors, GPS, Lidars, crank-shaft speed sensors etc. are all different devices that may be used to measure vehicle speed v.sub.x. An abnormal discontinuity in any of these speed measurements may be used to reset .sub.lim to the value held prior to the event. More in detail, discontinuity may be defined as a certain, preset, change in signal value within a set time interval.

(25) Trailer-mounted mechanical rotational angle sensors, GPS, Lidars, truck-mounted mechanical rotational angle sensors etc. are all different devices that may be used to measure the articulation angle . An abnormal discontinuity in any of these measurements may be used to reset .sub.lim to the value held prior to the event. More in detail, discontinuity may be defined as a certain, preset, magnitude in signal second derivative.

(26) The flowchart in FIG. 7 shows a method of reversing a vehicle combination 1 comprising a towing vehicle 1 and at least one trailer 20, whereby a reversing operation is initiated in step S10. As already mentioned hereinabove, the reversing operation may be manual, semi-automatic or even fully automatic, and controlled by the control unit 11 in the towing vehicle 10. In a following step S20, the control unit 11 may determine whether a jack-knifing condition J is about to occur by comparing a predicted future estimate of the articulation angle with the maximum safe articulation angle .sub.lim as estimated according to the first aspect of the present invention, such as shown and described in respect of FIG. 6. When it is determined that the jack-knifing condition is about to occur, at least one of a warning signal may be issued, represented by step S30, and a braking action may be initiated for the vehicle combination 1, represented by step S40.

(27) It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.