Method of controlling a vehicle combination

Abstract

A method of controlling a vehicle combination, the vehicle combination comprising a first vehicle unit, a second vehicle unit and an articulated coupling connecting the first and second vehicle units to each other, the method comprising determining a coupling force parameter of the articulated coupling based on a combination of motion related parameters obtained from the first and second vehicle units; selecting an operational envelope for the vehicle combination based on the coupling force parameter; and controlling the vehicle combination to operate within the operational envelope.

Claims

1. A method of controlling a vehicle combination, the vehicle combination comprising a first vehicle unit, a second vehicle unit, and an articulated coupling connecting the first and second vehicle units to each other, the method comprising: determining a coupling force parameter of the articulated coupling based on a combination of motion related parameters obtained from the first and second vehicle units; selecting an operational envelope for the vehicle combination based on the coupling force parameter; and controlling the vehicle combination to operate within the operational envelope and proactively avoid exceeding the operational envelope.

2. The method of claim 1, wherein the motion related parameters comprise an obtained first acceleration value indicative of an acceleration component of the first vehicle unit, and an obtained second acceleration value indicative of an acceleration component of the second vehicle unit.

3. The method of claim 1, wherein the motion related parameters comprise an obtained first angular acceleration value indicative of an angular acceleration of the first vehicle unit, and an obtained second angular acceleration value indicative of angular acceleration of the second vehicle unit.

4. The method of claim 1, wherein the motion related parameters comprise an obtained first wheel force value indicative of a longitudinal wheel force of at least one wheel of the first vehicle unit, and an obtained second wheel force value indicative of a longitudinal wheel force of at least one wheel of the second vehicle unit.

5. The method of claim 4, wherein the obtained first and second wheel force values indicative of the longitudinal wheel force are obtained from an actuator connected to the at least one wheel of the first and second vehicle units, respectively.

6. The method of claim 1, wherein the motion related parameters comprise an obtained angle value indicative of an articulated angle between the first and second vehicle units.

7. The method of claim 1, wherein the coupling force parameter is further based on an obtained weight value indicative of the weight of the first and second vehicle units, respectively.

8. The method of claim 1, wherein the coupling force parameter comprises a longitudinal force component and a transversal force component as seen relative to the longitudinal direction of the first vehicle unit.

9. The method of claim 1, wherein the coupling force parameter comprises a coupling torque component, the coupling torque component exposing the articulated coupling to a torque around a longitudinally extending geometric axis.

10. The method of claim 9, wherein the motion related parameters comprise an obtained vertical force value indicative of a vertical wheel force of at least one wheel of the second vehicle unit.

11. The method of claim 1, wherein the coupling force parameter comprises a vertical force component.

12. The method of claim 1, wherein the operational envelope is based on at least one of a maximum acceleration, maximum deceleration, and maximum steering angle.

13. A computer program product comprising program code for performing, when executed by a computer, the steps of claim 1 when the program is run on a computer.

14. A non-transitory computer readable medium comprising a computer program comprising program code, which when executed by a computer, performs the steps of claim 1 when the program means is run on a computer.

15. A control system for controlling a vehicle combination comprising a first vehicle unit, a second vehicle unit, and an articulated coupling connecting the first and second vehicle units to each other, wherein the control system is configured to be connected to a vehicle propulsion system, wherein the control system comprises control circuitry configured to: determine a coupling force parameter of the articulated coupling based on a combination of motion related parameters of the first vehicle unit and the second vehicle unit; select an operational envelope for the vehicle combination based on the coupling force parameter; and transmit a control signal to a vehicle propulsion system, the control signal representing instructions to operate the vehicle combination within the operational envelope and proactively avoid exceeding the operational envelope.

16. A vehicle combination comprising a first vehicle unit, a second vehicle unit, an articulated coupling connecting the first and second vehicle units to each other, a vehicle propulsion system arranged to propel the vehicle during operation, and the control system of claim 15.

17. The vehicle combination of claim 16, wherein the first vehicle unit is an autonomously controlled vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above, as well as additional objects, features and advantages, will be better understood through the following illustrative and non-limiting detailed description of exemplary embodiments, wherein:

(2) FIG. 1 is a lateral side view illustrating an example embodiment of a vehicle combination in the form of a truck, where the vehicle combination comprises a first and a second vehicle unit;

(3) FIG. 2 is a top view of the first and second vehicle units of FIG. 1;

(4) FIG. 3 is a side view of the first and second vehicle units of FIG. 1;

(5) FIG. 4 is a rear view of the first vehicle unit in the vehicle combination in FIG. 1;

(6) FIG. 5 is a rear view of the second vehicle unit in the vehicle combination in FIG. 1;

(7) FIG. 6 is a control system for controlling the vehicle combination in FIG. 1 according to an example embodiment;

(8) FIG. 7 is a diagram illustrating an operational envelope for the vehicle combination according to an example embodiment; and

(9) FIG. 8 is a flow chart of a method for controlling the vehicle combination in FIG. 1 according to an example embodiment.

DETAILED DESCRIPTION

(10) The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. The disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness. Like reference character refer to like elements throughout the description.

(11) With particular reference to FIG. 1, there is depicted a vehicle combination 100 in the form of a multi-trailer truck 100. The vehicle combination 100 comprises a first vehicle unit 102, a second vehicle unit 104, a third vehicle unit 106 and a fourth vehicle unit 108. The first vehicle unit 102 is a tractor unit, a trailing unit, while the second 104 and fourth 108 vehicle units are arranged as trailer units, and the third vehicle unit 106 is a dolly arranged between the second 104 and fourth 108 vehicle units. Although the vehicle combination 100 depicted in FIG. 1 comprises four vehicle units, the present disclosure is equally applicable for a vehicle combination comprising arbitrary many vehicle units, such as e.g. also a fifth, a sixth, a seventh vehicle unit, etc.

(12) Moreover, the first vehicle unit 102 is connected to the second vehicle unit 104 by a first articulate coupling 110, the second vehicle unit 104 is connected to the third vehicle unit 106 by a second articulate coupling 112, and the third vehicle unit 106 is connected to the fourth vehicle unit 108 by a third articulate coupling 114. Hereby, the vehicle units are allowed to rotate relative to each other around a respective first 116, second 118 and third 120 substantially vertical geometric axis.

(13) During operation, the articulated couplings 110, 112, 114 of the vehicle combination 100 are exposed to coupling forces, such as e.g. longitudinal and lateral forces, as well as torque loads. These coupling forces are generated during operation of the vehicle combination. In order to describe these coupling force parameters in further detail, reference is made to FIGS. 2-5 which illustrate an example embodiment of a vehicle combination 100 comprising the first 102 and the second 104 vehicle units. Thus, the following disclosure will, for simplicity of understanding, not include the third 106 and fourth 108 vehicle units of the vehicle combination in FIG. 1. However, it should be readily understood that the coupling force parameters of the second 112 and third 114 articulated couplings are determined in a similar manner as for the first articulated coupling 110 described below.

(14) Starting with FIG. 2, which is a top view of the first and second vehicle units of FIG. 1. The vehicle combination 100 is in FIG. 2 arranged in a somewhat exploded view so that the first vehicle unit 102 is separated from the second vehicle unit 104. Thus, FIG. 2 is exploded in this manner to simplify the illustration of the coupling force parameters of the first articulated coupling 110 as well as the motion related parameters obtained from the first 102 and second 104 vehicle units.

(15) As can be seen in FIG. 2, the first vehicle unit 102 turns to the left by an articulated angle . Thus, the first vehicle unit 102 and the second vehicle unit 104 are rotated relative to each other around the articulated coupling 110 by the articulated angle . The articulated angle can be measured by e.g. an angle sensor, an input signal from the steering wheel, and/or from an Advanced driver-assistance system (ADAS). Further, during propulsion, the vehicle is exposed to a longitudinal acceleration component, a.sub.x1, and a lateral acceleration a.sub.y1. The lateral acceleration a.sub.y1 is generated as the first vehicle unit 102 is turning. The longitudinal and lateral acceleration components can be determined by means of inertial measurement units (IMUs) or similar sensors.

(16) The second vehicle unit 104 is exposed to a longitudinal acceleration component, a.sub.x2, as can also be obtained by an IMU. As the second vehicle unit 104 in FIG. 2 is still operated straight forward, it is not exposed to a lateral acceleration component at this stage.

(17) Furthermore, when the vehicle combination is operated, actuation forces, F.sub.x1 and F.sub.x2, of the first 102 and second 104 vehicle units can be obtained from actuators of the vehicle, such as e.g. electric machines configured to generate an operating torque on the propelled wheels of the respective first 102 and second 104 vehicle units. Based on the above described motion related parameters, the following equations (1)-(6) can be generated to determine the coupling force parameters of the articulated coupling.
m.sub.1a.sub.x1=F.sub.x1+F.sub.xc(1)
m.sub.2a.sub.x2=F.sub.x2F.sub.xc cos()F.sub.yc sin()(2)
m.sub.1a.sub.y1=F.sub.y1F.sub.yc(3)
m.sub.2a.sub.y2=F.sub.y2F.sub.xc sin()+F.sub.yc cos()(4)
J.sub.z1{dot over ()}.sub.z1=F.sub.y1L.sub.x1+F.sub.ycL.sub.c1(5)
J.sub.z2{dot over ()}.sub.z2=F.sub.y2L.sub.x2+L.sub.c2(F.sub.xc sin()+F.sub.yc cos())(6) Where: m.sub.1 is the mass of the first vehicle unit 102; m.sub.2 is the mass of the second vehicle unit 104; {dot over ()}.sub.z1 is the angular acceleration of the first vehicle unit 102; {dot over ()}.sub.z2 is the angular acceleration of the second vehicle unit 104; F.sub.y1 is the lateral forces generated on the first vehicle unit 102; F.sub.y2 is the lateral forces generated on the second vehicle unit 104; J.sub.z1 is the moment of inertia of the first vehicle unit 102; J.sub.z2 is the moment of inertia of the second vehicle unit 104; L.sub.x1 is the longitudinal length from the center of mass of the first vehicle unit 102 to a position at which the lumped tractive force F.sub.x1 is exposed to the first vehicle unit 102; L.sub.c1 is the longitudinal length from the center of mass of the first vehicle unit 102 to the position of the articulated coupling 110; L.sub.x2 is the longitudinal length from the center of mass of the second vehicle unit 104 to a position at which the lumped tractive force F.sub.x2 is exposed to the second vehicle unit 104; L.sub.x2 is the longitudinal length from the center of mass of the second vehicle unit 104 to the position of the articulated coupling 110; F.sub.xc is the longitudinal coupling force component as seen in a local coordinate system of the first vehicle unit 102; and F.sub.yc is the lateral coupling force component as seen in a local coordinate system of the first vehicle unit 102.

(18) The angular accelerations {dot over ()}.sub.z1 and {dot over ()}.sub.z2 can, in a similar manner as the longitudinal and lateral acceleration components be determined by obtaining a signal from an IMU or similar sensor. The mass of the first 102 and second 104 vehicle units, as well as the moments of inertia J.sub.z1 and J.sub.z2 are also known beforehand.

(19) Thus, the above equations (1)-(6) contains the known parameters m.sub.1, m.sub.2, a.sub.x1, a.sub.x2, a.sub.y1, {dot over ()}.sub.z1, {dot over ()}.sub.z2, J.sub.z1 and J.sub.z2 and the unknown parameters F.sub.xc, F.sub.yc, F.sub.y1 F.sub.y2 L.sub.x1 L.sub.x2. Thus, six equations and six unknown parameters, which presents an equation system which is solvable. In particular, the coupling force parameters F.sub.xc and F.sub.yz can be determined, which can be used for the application as described further below in relation to FIG. 7.

(20) The above described longitudinal forces F.sub.x1 and F.sub.x2 are thus the sum of wheel torques, i.e. actuated torque from brake and/or propulsion units, among the wheels of the respective vehicle unit divided by the wheel radius.

(21) Turning now to FIGS. 3-5, which are a side view and rear views of the vehicle combination 100 according to an example embodiment. In particular, FIG. 4 is a rear view of the first vehicle unit 102 and FIG. 5 is a rear view of the second vehicle unit 104. Motion related parameters already described in relation to FIG. 2 will not be described in further detail below but should be construed as also being present for the illustrations of FIGS. 3-5.

(22) From the illustrations of FIGS. 3-5, the following equations (7)-(19) can be generated:

(23) $\begin{array}{cc}{M}_{xc}+F_{z212}\frac{W_2}{2}-F_{z211}\frac{W_2}{2}-m_2{a}_{y2}\left(h_2-h_t\right)=0& \left(7\right)\end{array}$$\begin{array}{cc}{M}_{xc}+\left(F_{z111}+F_{z121}\right)\frac{W_1}{2}-\left(F_{z112}+F_{z122}\right)\frac{W_1}{2}-m_1{a}_{y1}\left(h_t-h_1\right)=0& \left(8\right)\end{array}$$\begin{array}{cc}{F}_{zc}+F_{z21}-m_2{a}_{z2}=0& \left(9\right)\end{array}$$\begin{array}{cc}-F_{zc}+F_{z11}+F_{z12}-m_1{a}_{z1}=0& \left(10\right)\end{array}$$\begin{array}{cc}{F}_{z11}=F_{z111}+F_{z112}& \left(11\right)\end{array}$$\begin{array}{cc}{F}_{z12}=F_{z121}+F_{z122}& \left(12\right)\end{array}$$\begin{array}{cc}{F}_{z21}=F_{z211}+F_{z212}& \left(13\right)\end{array}$$\begin{array}{cc}{F}_{xc}\cos \left(\right)+F_{\mathrm{yc}}\sin \left(\right)+m_2{a}_{x2}-F_{x2}=0& \left(14\right)\end{array}$$\begin{array}{cc}{F}_{xc}+F_{x1}-m_1{a}_{x1}=0& \left(15\right)\end{array}$$\begin{array}{cc}{F}_{\mathrm{yc}}=F_{y11}+F_{y12}-m_1{a}_{y1}& \left(16\right)\end{array}$$\begin{array}{cc}{F}_{\mathrm{yc}}\cos \left(\right)-F_{xc}\sin \left(\right)-m_2{a}_{y2}+F_{y21}=0& \left(17\right)\end{array}$$\begin{array}{cc}{F}_{x1}{h}_t-m_1{a}_{x1}\left(h_t-h_1\right)=0& \left(18\right)\end{array}$$\begin{array}{cc}{m}_2{a}_{x2}\left(h_2-h_t\right)-F_{x2}{h}_t=0& \left(19\right)\end{array}$

(24) As described above in relation to the description if FIG. 2, the acceleration parameters can be determined by e.g. IMUs and the tractive forces can be obtained from the actuators. Hereby, the vertical coupling force F.sub.yc and the coupling torque M.sub.xc of the articulated coupling can be determined.

(25) Turning to FIG. 6 which illustrates a control system 600 according to the present disclosure. The control system 600 depicted in FIG. 6 is arranged to determine the above described longitudinal coupling force F.sub.xc and lateral coupling force F.sub.yz. It should however be readily understood that the control system 600 is equally applicable for determining the vertical coupling force F.sub.xc and the coupling torque M.sub.xc by implementing also the equations (7)-(19) described above.

(26) The control system 600 comprises control circuitry 650 which may each include a microprocessor, microcontroller, programmable digital signal processor or another programmable device. The control circuitry 650 may also, or instead, each include an application specific integrated circuit, a programmable gate array or programmable array logic, a programmable logic device, or a digital signal processor. Where the control circuitry 650 includes a programmable device such as the microprocessor, microcontroller or programmable digital signal processor mentioned above, the processor may further include computer executable code that controls operation of the programmable device. It should be understood that all or some parts of the functionality provided by means of the control circuitry 650 may be at least partly integrated with the below described IMUs 130, 230, actuators 140, 240, angle sensor 250 and mass and inertia estimator 602.

(27) As can be seen, the control system 600 receives a longitudinal acceleration component a.sub.x1, a lateral acceleration component a.sub.y1 and a rotational velocity component .sub.z1 from an IMU 130 of the first vehicle unit 102. The control system 600 also receives longitudinal wheel forces F.sub.x1 from the first vehicle unit 102, which are defined as a sum, calculated by a first force summation module 170, of longitudinal wheel forces received from actuators 140 of the first vehicle unit 102.

(28) Moreover, the control system receives a longitudinal acceleration component a.sub.x2, a lateral acceleration component a.sub.y2 and a rotational velocity component .sub.z2 from an IMU 230 of the second vehicle unit 104. The control system 600 also receives longitudinal wheel forces F.sub.x2 from the second vehicle unit 104, which are defined as a sum, calculated by a second force summation module 270, of longitudinal wheel forces received from actuators 240 of the second vehicle unit 104. Also, the control system receives an articulated angle of the articulated coupling 110, i.e. the relative angular displacement between the first 102 and second 104 vehicle units. Although FIG. 6 illustrates that the articulated angle is received from an angle sensor 250 of the second vehicle unit 104, this angle sensor 250 can equally form part of the first vehicle unit 102.

(29) Moreover, the control system 600 receives parameter values indicative of vehicle mass m and moment of inertia J from a mass and inertia estimator 602. Thus, the mass and inertia estimator 602 is arranged to transmit parameter values indicative of the mass m.sub.1 of the first vehicle unit 102, the mass m.sub.2 of the second vehicle unit 104, the moment of inertia J.sub.1 of the first vehicle unit 102 and the moment of inertia J.sub.2 of the second vehicle unit 104.

(30) When receiving the motion related parameters of the first 102 and second 104 vehicle units, the control system determines, based on the above described equations, the coupling force parameters, here indicated as the longitudinal F.sub.xc and lateral F.sub.yc coupling force parameters, of the articulated coupling.

(31) Based on the coupling force parameters, the vehicle combination is controlled to operate within an operational envelope, as is exemplified in FIG. 7. The control system 600 thus, based on the determined coupling force parameters, selects an operational envelope within which the vehicle should be controlled. In the example of FIG. 7, the vertical axis 702 represents the longitudinal acceleration of the vehicle combination and the horizontal axis 704 represents the steering angle. The operational envelope 700 may of course be based on other control parameters as well, such as an increase and/or decrease of the length (when such length is adjustable) of the vehicle combination, vehicle speed, etc. Accordingly, the operational envelope defines operating conditions that the vehicle combination should fulfil to be operated in a safe manner.

(32) In order to sum up, reference is made to FIG. 8, which is a flow chart of a method for controlling the above described vehicle combination according to an example embodiment. During operation of the vehicle combination, at least one of the coupling force parameters is determined S1 based on the combination of motion related parameters obtained from the first 102 and second 104 vehicle units. These motion related parameters are described in detail above with reference to FIGS. 2-5.

(33) Thereafter, an operational envelope 700 is selected S2 for the vehicle combination 100 based on the determined coupling force parameters of the articulated coupling 110. The vehicle combination is thereafter, for being safely operated, controlled S3 to operate within the selected operational envelope 700.

(34) It is to be understood that the present disclosure 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.