FR2515379A1 - Reverse motion stabiliser system for articulated lorry - uses angle sensors on tractor and trailer connected to power steering motor - Google Patents

Abstract

The tractor (10) has steering applied to its front wheels while the rear wheels are fixed. The wheels of the rear of a trailer are also fixed. A signal processing unit (40) receives a signal from a potentiometer (81) set by the driver to represent the radius of curvature of the track to be followed. Angle detectors (Pa,Pb) in the tractor and trailer measure actual directional angles. Representative signals are applied to the processing unit where amplifiers (41,42,43) and summers (44,45,46) resolve an error signal. The error signal is applied to a control unit (70) which controls a motor (61) to modify the steering angle of the steerable wheels on the tractor. The driver can modify the steering track by adjustment of the potentiometer.

Description

The present invention relates to a stabilization device in reverse of a set of articulated vehicles
It is well known that it is particularly difficult to maneuver in reverse with a set of articulated vehicles comprising for example a tractor and a semi-trailer.

 Indeed, such a set is particularly unstable regardless of the trajectory (straight line or curve) that the driver of the set wants to follow. The driver is thus led to correct, by means of its steering wheel, the induced oscillations of the semitrailer.

 The problem is further complicated when it is a set, commonly called "road train", comprising a tractor and a trailer.

 Indeed, it can be considered that a trailer is a vehicle consisting of two semi-trailers, a front and a rear, and a container. It is secured to the rear semitrailer, the front semitrailer being free to rotate about a pivot disposed on the longitudinal axis of the rear semitrailer and hitched to the preceding vehicle (tractor in the case of a road train).

 Therefore, a road train (tractor and trailer) is likened to an assembly comprising a tractor and two semitrailers and it is understood that the maneuver in reverse is even more delicate than when there is only one semitrailer only: together may oscillate strongly and become virtually uncontrollable in reverse.

 Until now, only the experience and the habit of the driver made it possible to overcome these difficulties.

 The disadvantage is therefore essentially a stabilizing device in reverse, especially for tractor and semi-trailer assembly or for a road train, but also for all sets of articulated vehicles including at least one motor vehicle and at least one semi-trailer, said assembly comprising at least one directional steerable train lying behind a semitrailer, relative to the operating direction of the device, such as reversible construction machines, articulated buses, military vehicles, etc. ...

 According to the invention, this device is characterized in that it comprises, in combination with a power member adapted to act on the steering wheel of the steering gear, at least one steering gear angle sensor establishing signal of driving angle, a hinge angle sensor, associated each of the semitrailers establishing a duct angle signal and a processing member adapted to develop, from said leading angle and duct angle signals, and at least one curvature setpoint signal to be followed, a servo signal of said power unit.

 Thanks to the device according to the present invention, the stabilization in reverse of a set of articulated vehicles is done automatically, the driver only having to display the curvature of the road to follow and possibly to change this instruction as soon as the curvature changes.

 This device consequently simplifies the work of the driver in a remarkable way and in addition, makes it possible to perform certain maneuvers in reverse significantly faster and more efficiently than in the past.

 In addition, the means available to those skilled in the art for producing the device according to the present invention, are quite inexpensive, so that the cost and maintenance of said device are particularly low.

The features and advantages of the present invention will emerge from the following description, with reference to the appended drawings in which:
- Figure 1 shows in plan, schematically, a set of vehicles comprising a tractor and a semi-trailer;
- Figure 2 shows a block diagram of an embodiment of a device according to the present invention for stabilizing in reverse the above assembly;
- Figure 3 shows in plan, schematically, a road train comprising a tractor and a trailer;
- Figure 4 shows a block diagram of a second embodiment of a device according to the present invention for stabilizing in reverse the road train.

 In the description which follows, the embodiment chosen and shown in FIGS. 1 to 4 represents a device according to the present invention applied to the stabilization in reverse of road assemblies, but it goes without saying that any other set of articulated venicles may be suitable.

 It is first of all necessary to define the meaning given to the terms "semi-trailer" and "trailer" in the context of the present description and to give succinctly the conditions of stabillce in reverse of a set of articulated vehicles.

 Reference is made to Figures n and 3.

 In Figure 1, a set of articulated vehicles having a tractor 10 and a semitrailer vehicle 20 is shown. The tractor 10 comprises a steerable steering gear 13 having wheels Il that the driver can steer by means of his steering wheel. The tractor comprises, in the example shown, a fixed gear 14. The longitudinal axis of symmetry 12 of the tractor 10 is also considered.

 The semi-trailer vehicle 20 has a longitudinal axis of symmetry 22 and a pivot point 25 secured to the tractor 10 by any suitable means known to those skilled in the art.

 In Figure 3, a road train is shown. It has a 10 'tractor and a VR trailer. The tractor 10 'comprises, like the tractor 10, a steerable steering gear 13' comprising wheels 17 ', a fixed gear 14' and an axis of symmetry 12 '.

 The VR trailer has two semi-trailers 20 and 30.

For the purposes of the present invention, a semi-trailer is called not only a semi-trailer road vehicle but also, and by extension, any rigid structure, for example a beam, carrying, at one of its ends, a hinge and in one another point one or more rigid axles so-called, in this description, fixed train.

Also, according to the present description, a road trailer such as the trailer VR comprises two semi-trailers 20 'and 30' defined by their longitudinal axis of symmetry, respectively 22 'and 32', their fixed train,
respectively 24 'and 34' and their point of articulation
respectively 25 'and 35'. The container (not shown)
of the trailer VR is attached to the semitrailer 30 '.

The theoretical study of stability in reverse
of an assembly such as those represented in FIGS. 1 and 3,
shows that, as a first approximation, one can ask, at each
moment, when the whole is stabilized on a curve of
given radius R, an equation of the type:
= cp = cbW = dR (1)
where α = instantaneous turning angle of the wheels 11 (11 ') of the
steering gear 13 (13 ') of the tractor 10 (10'), called
director's corner
= instantaneous angle between longitudinal axis 12 (12 ') of
tractor 10 (10 ') and the longitudinal axis 22 (22') of
the semi-trailer 20 (20w)
r- instantaneous angle between the axes 22 'and 32' of semi
20 'and 30' trailers
R: instantaneous radius of curvature of the path followed in
reverse b, c, d: constants depending on the characteristics of the sets
represented roadways: distance between wheel trains,
distance from wheel trains to articulation points
and towing, wheel spacing, etc ...

In the case of a road combination comprising only one
tractor and a semi-trailer, the correction to be made to any
moment at the turntable of the steering wheels
13 is of type: 8 (Vt) = k1 (a po) + k2 (0) (2)
where k1, k2: setting constants
α o, sso, Ro: angles and set radius where, following 1 '
equation (1): # o = c sso = dRo
An embodiment of the invention will now be
described in support of Figure 2.

The device according to the invention essentially comprises
a processing unit (in this case a logi
40 as a block diagram of functions), an angle sensor Pd installed in the tractor, an angle sensor Pss installed in the semi-trailer, a power unit 60 having a motor 61 for modify the steering angle of the wheels 11 of the steering gear 13, a control member 70 of said power member and a set member 80.

 The logic unit 40 comprises three amplifiers 41, 42, 43 of variable gain and three summing members 44, 45, 46. The gain of the amplifier member 41 is equal, in this case, to k1. The gain of the amplifier 42 is, in this case, equal to c. Similarly, the amplifier 43 is assigned a gain equal to k2.

 The logic unit 40 has three inputs 47,48, 49 and an output 50.

 The control member 70 comprises the elements necessary for the transformation of the control signal s (cc) into an electrical signal actuating the motor 61.

 The logic unit 40 is, thanks to the amplifier and summator organs, adapted to provide a signal according to the same law as that defined by equation (2). For this purpose, the detector P is a device adapted to measure the turning angle of the wheels of the steering gear and transforming this measurement into a driving angle electrical signal which is delivered to the input 49 of the logic unit 40 Likewise, the electrical signal at the input 47 of the logic unit is representative of the angle p (direction angle signal).

The reference device 80 essentially comprises an amplifier 83 whose gain (d) is such that the signal at the
c output of this setpoint member, delivered to the input 48 of the logic unit 40, is representative of the setpoint angle Ro if a signal representative of the ro ray Ro of the amplifier is applied to the input of the amplifier. the curvature that the driver wishes to follow. This result is obtained by means of the potentiometer 81 and the voltage source 82.

 The signal, at the output 50 of the logic unit 40, is delivered to the control member 70, which controls the motor 61 of the power unit 60.

 The power unit 60 comprising the motor 61 being adapted to act on the steering wheel of the steering gear 13, the signal s (α) at the output Vu of the processing unit or logic unit 40, is enslaved said power unit to the curvature reference value Ro to be followed.

 Several variants of embodiment of the member 70 of the motor 61 acting on the steering of the wheels 11 will now be described.

 The Applicant's studies and experiments have shown that the speed of variation of the steering of the wheels must be related to the speed of recoil of the road train and to the variations of this speed of recoil.

 For the various cases of use of a set of articulated vehicles in reverse, the Applicant has been led to develop various control devices 70.

1.- Constant speed of recoil:
The range of recoil speeds is very limited (eg 0-5km / h).

The driver of the vehicle chooses a speed and sVy maintains. According to the embodiment shown, two types of control members 70 can be made:
- All-or-nothing order:
The controller 70 detects the sign of the signal s (α) and rotates the motor 61 in one direction or another, depending on this sign. The rotational speed of the motor 61 is constant in each direction. The steering angle of the wheels It increases or decreases accordingly.

The variation of the angle α steering wheel can be expressed as follows:
α = + k (s (α)> o)
&alpha; = - k (s (&alpha;)<o) k = proportionality constant
Proportional speed control (or integral in
position):
The controller 70 detects the sign and the amplitude of the signal s () and delivers a signal that rotates the motor 61 at a speed proportional to the signal s ().

The variation of the steering angle of the wheels can be expressed as follows: = ks (>) k, proportionality constant
2.- Any speed of recoil:
The range of possible recoil speeds is wider than in the previous case (eg 0-20km / h).

 The driver of the road train makes the speed of recoil of the road train vary considerably. Two types of control members 70 can be made.

- All-or-nothing order:
This is a type of control equivalent to the type described above, the speed of rotation of the motor 61 being proportional to the speed of recoil of the road train, the variation of the angle of turn of the wheels can express itself as follows: a = + kv (s (&alpha;)> o)
&alpha; = - kv (s (t) <o) v = the setback speed of the measured road set,
known manner, by a tachometer device,
this device being incorporated in the organ 70 k = proportionality constant
- proportional control in speed (or integral in
position)
This is a control of the same type as that described above, the speed of rotation of the motor 61 being proportional to the speed of recoil of the road train.

The variation of the steering angle of the wheels can be expressed as follows: t = kvs () v. recoil speed k = proportionality constant
In operation, the driver displays a radius of curvature Ro by means of the potentiometer 81. The angle detectors P &alpha; and Pss detect angles &alpha; and ss and transmit signals representative of these angles to the logic unit 40.The processing of these signals in the logic unit 40 allows the latter to deliver a signal s () at its output 50, this signal being transformed into the control member 70 into a signal acting on the speed of the motor 61, as described above. the steering angle of the wheels It is therefore modified accordingly and the road train steadily retreats on a curved trajectory whose radius is equal to Ro.

 Of course, the driver can modify this radius at any time by means of the slider of the potentiometer 81 and, the gains k1 and k2 of the amplifiers 41 and 43 being suitably adjusted, the device is obtained a correct response to any variations of the setpoint. If the speed of recoil is large and the variations thereof also, the gains of the amplifiers 41, 43 and the proportionality constant k of the controller 70 are determined accordingly to obtain a satisfactory response of the system.

 Means known to those skilled in the art, such as timer, shunting, integrator, can be mounted both in the control member 70 and in the logic unit 40, to improve the overall gain of the control loop and the time of the response thereof, while ensuring a good stability of this control loop.

 FIG. 4 will now describe an embodiment of the device according to the invention for rear stabilization of the road train comprising a tractor and a trailer.

Good stability can be obtained on the assumption that the tractor unit 10'-first semi-trailer 20 'is already stable thanks to the device described in support of FIG. 2 and that consequently, it is necessary and sufficient to stabilize the third element, ie the 30tw semi-trailer
In other words, it is necessary to control the angle between the tractor and the semitrailer 20 'to eliminate oscillations of the angle s between the semi-trailers 20' and 30 '(see Figure 3) .The correction made at any time, the angle is of the type: s () = k3 (# - #o) + k4 (fi (3) k3, k4 = setting constant sso, yo, Ro = angles and reference radius or l 'equality (1) is
respected, which gives: - b 21O = dRo
Of course, equation (2) still remains valid:
s (. <) = k1 (A- sso) + k2 (- foo)
In FIG. 4, a road train comprising a tractor 10 and a trailer VR is schematically illustrated in FIG.
The device according to the invention essentially comprises, in this embodiment, a processing unit OT (in the present case, two logical units 40, 40 'represent a block diagram of functions and an interface element 90), the angle detectors PZ and Pss, installed in the tractor and the semitrailer, as previously described in support of FIG. 2, and an angle detector Pg installed in the trailer and producing a signal angle of the conduit as well as the same control power elements 70 and command 80 that those described in support of Figure 2.

 The logical units 40, 40t are identical to the logical unit described in FIG. 2. The gain of the element 41 is equal to k1 that of the amplifier 42 to c, that of the amplifier 43 to 42, that of the amplifier 41 'to k3, that of the amplifier 42' to b and that of the amplifier 43 'to k4.

 The angle detectors Pi and Pss are connected in the same manner as before to the logic unit 40, the angle detector a being additionally connected to the input 49 'of the logic unit 40'. The detector Py is connected to the input 47 '. A reference device 80, identical to that described in support of FIG. 2, is connected to the input 48 'of the logic unit 40', the gain of the amplifier 83 being taken to be equal so that if an image voltage of the setpoint radius Ro is applied to the input of this amplifier. At the output of this amplifier there is a signal representative of the setpoint angle uo (see equation (2)).

 Similarly, the signal at the output 50 of the logic unit 40 is delivered to the controller 70. The logic units 40w and 40 are connected via an interface member 90 disposed between the output 50 of logic unit 40 and input 48 of logic unit 40.

 The operation of this embodiment of the invention is identical to that previously described. The driver displays a radius of curvature Ro by means of the potentiometer 81, and the combination of means, power member 60 adapted to act on the steering wheels 11 of the steering gear 13, steering gear angle sensor Pw establishing a signal of leading angle (alpha), articulation angle sensors,, Pr, associated with semitrailers 20 'and 30' consecutively establishing direction angle signals (S, Y) OT processing member adapted to elaborate from said angle signals leading, driven angles, and the curvature command signal to follow, allows to establish a servo signal s () of said power member. The trajectory followed by the road train is therefore a curve of radius of curvature XO.

 The structure of the member 90 is chosen according to the same criteria as those mentioned above with respect to the control member 70. In reality, the role of this member is to "control" the angle ss just like that of the 70 is to "control" the angles through the power member 60.

 The structure of the member 90 must therefore take into account the speed of recoil of the road train and variations in this speed.

 In addition, according to the embodiment described, the output signal of the logic units 40, 40 'being a speed control signal and the input signals in these units being position signals, and especially at the input 48 or 48 ', interface member 90 must include an integrator so that its output signal is a position signal.

où v I vitesse de recul du train routier
Bien entendu, l'invention ne se limite pas aux formes de réalisation décrites et représentées, mais englobe toutes variantes d'exécution.1- Constant speed of recoil:
The member 90 comprises in this case a constant gain amplifier in addition to the integrator, so that the signal at the output of this interface member is of the type:
ss 1 = #ks (ss) dt where 1 = output signal
s (, g) signaled at logic unit output 40 '
k "gain of the amplifier
2- Variable recoil speed:
The member 90 further comprises an input receiving a tachometric signal representative of the speed of recoil of the road train. The signal at the output of the interface member is then tvDe:

where v I speed of retreat of the road train
Of course, the invention is not limited to the embodiments described and shown, but encompasses all alternative embodiments.

 For example, the signal at the output of the logic units 40 and / or 40 'may be a control signal in position.

In the latter case, the control member 70 comprises, for example, a differentiator in addition to the other elements described, the interface member 90 having, for its part, no integrating element.

 Other means, known to those skilled in the art, can also be used for the production of organs 70 and 90.

 In addition, in the embodiment and the particular examples shown in FIGS. 1 to 4, the duct and Y angles have been represented as the angles formed by the longitudinal axes of the semi-trailers and the tractor. It goes without saying that they can, in other embodiments, represent, for example, the steering angle of the wheels of a steerable train of a driven vehicle.

 It goes without saying also that the invention can not be limited to the stabilization and control in reverse of an assembly comprising at most two trailer vehicles or ducts.

 The case shown in Figures 3 and 4 can be generalized to an assembly comprising more than two semi-trailers and in general more than two led angles. It is sufficient, for example in the latter case, to associate with each additional corner angle an angle detector, a logic unit card 40 and an additional interface member 90. The additional lead angle sensor is connected to the input 47 of the logic unit 40, the input 49 being connected to the lead angle detector preceding said additional lead angle; the interface member 90 being disposed between the output 50 and the input 48 of two consecutive logical units 40; the reference device 80 being connected to the input 48 of the last logical unit. The gains of the amplifiers being properly adjusted, a stable and rapid response to any setpoint variation is obtained.

Claims (5)

 1-device for stabilizing a set of articulated vehicles, including at least one motor vehicle and at least one semi-trailer, said assembly comprising at least one steerable train with a steering train located behind a vehicle driven by relative to the direction of travel, in operation of the device, each vehicle comprising one or two semi-trailers, this device being characterized in that it comprises, in combination with a power member (60) adapted to act on the steering of wheels (11) of the steering gear (13), at least one steering angle sensor (PX) a establishing a driving angle signal, a sensor (Pfl Py) of articulation angle (P, Y) , associated with each of the hinge points of the semi-trailers establishing a duct angle signal and a processing member (OT) adapted to develop from said leading angle signals and led angle, and at least a curvature command signal to follow (R), a s servo ignal (8 ()) of said power member.  2- Device according to claim 1, characterized in that it comprises an angle sensor associated with each steerable train of a driven vehicle establishing a led angle signal.  3- Device according to one of claims 1 2, characterized in that the curvature signal to be followed is developed by a potentiometer whose cursor is the control means of the radius of curvature (Ro)  4- Device according to any one of claims 1 to 3, characterized in that it further comprises, a control member (70) acting on the power member (60) in response to said servo signal,  5- Device according to claim 4, characterized in that the control member comprises a tachometer device adapted to measure the speed of recoil of.l> set of articulated vehicles0