TECHNICAL FIELD The present invention relates to a guide device for self-alignment of an agricultural implement 5 coupled towed including a tractor type of vehicle. PRIOR ART Today, tractors, combine harvesters and other agricultural vehicles are being used to guide tractors, combine harvesters and other agricultural vehicles in order to partially eliminate the laboriousness of working in the fields and to enable the driver to concentrate on its equipment and performance. These guiding devices help to increase productivity and reduce costs in all activities, by allowing the driver to focus on optimizing parameters, such as the working width of the tool or table of operation. cutting, and more closely monitoring work, for optimal and accurate use for better quality output and increased productivity. These guiding devices have many advantages and make it possible in particular to: - the elimination of overlaps and forgotten surfaces, - savings in fuel, time and costs, - a reduction in the wear of the active zone of the working members tools and / or machines, - a significant reduction in the driver's fatigue of the agricultural vehicle, - the reduction of soil compaction, thanks to a reduced number of passages. - control of the farm's traffic, CECC01-FR-1TEXTE DEPOSERG-GE - better crop establishment. Most of the known guidance devices use Global Positioning System (GPS) -based navigation and have three elements: a touch-screen preferred terminal, a fixed or mobile base station, and a roof module. The touchscreen terminal allows the user to control the guidance of the tractor or combine by viewing the main elements such as real-time accuracy, sensitivity and tool behavior. The base station has a GPS antenna and a radio module and can generate the desired differential correction of the trajectory of the tractor or the combine and spread it within a radius of several kilometers. The roof module disposed on the tractor uses at least one antenna to perfectly control in real time the position of the tractor or the combine harvester 20 along two or three axes. These guiding devices, which are effective for monobloc agricultural machines or having mounted tools, have drawbacks when said machines pull a plow-type tool for example. In fact, these guiding devices allow only a correction of the trajectory of the tractor. The towed tool therefore only follows the tractor oscillating on both sides of the direction of movement of said tractor and its trajectory is not corrected in real time, which has the effect of generating grooves which are not completely rectilinear but presenting waves. To correct this problem, guidance devices are already known which are arranged on the towed tool and make it possible to correct the trajectory and / or the orientation of said agricultural implement. These guiding devices comprise for example a beam arranged cantilevered at the rear of the agricultural tool and bearing the working members of said agricultural implement. Said beam is able to move perpendicularly to the longitudinal axis of the agricultural implement under the effect of a double-acting cylinder-type actuator, said actuator being slaved to navigation based on the GPS geolocation system. of the agricultural tool. However, these devices have a number of disadvantages. Indeed, they do not take into account the position of the tractor and do not allow to align the towed agricultural implement relative to the tractor. In addition, because of the weight and the cantilevered position of the beam, they handicap the movement of the agricultural implement and therefore slow down the correction of the position of said agricultural implement. Finally, these devices, which can be implemented on only one type of agricultural tool because of their design, have a significant cost and thus the total cost of the agricultural tool. SUMMARY OF THE INVENTION The object of the present invention is thus to overcome the aforementioned drawbacks and to propose an alternative solution to the known guiding devices. The present invention therefore aims at providing a device for guiding a harnessed agricultural implement drawn in particular by a tractor-type machine that is simple, inexpensive, effective, adaptable whatever the type of agricultural tool and allows self-alignment of said agricultural tool compared to the tractor. In this regard, it is therefore proposed a guiding device for guiding a tractor type of vehicle according to a predetermined map and self-alignment CECCO1 -FR-1 _TEXTE DEPOSE_RG-G of an agricultural implement pulled by said tractor thanks to a hitch comprising at least one articulated hitch arm at each of its ends respectively to the agricultural implement and to the tractor, remarkable in that it comprises at least a first GPS antenna arranged to be arranged on the agricultural tool and an actuator arranged to be articulated between said tractor and linkage arm, said actuator being servocontrolled by said first and second GPS antennas by a control station to move said lower linkage arm relative to said car tractor. -align the agricultural tool with respect to the latter. According to a preferred embodiment, the guiding device comprises a second GPS antenna arranged to be arranged on the tractor and coupled to said first GPS antenna for controlling said actuator. Preferably, the guiding device comprises a touch screen terminal. Likewise, the guiding device is advantageously coupled to an automatic device for controlling and controlling the direction of the tractor in order to automatically guide the latter without the intervention of the driver. According to an advantageous embodiment, the actuator 25 is a double-acting cylinder, said actuator preferably being a hydraulic cylinder connected to the hydraulic system of the tractor. The invention also relates to a tractor towing an agricultural implement by means of a hitch comprising at least one articulated hitch arm at each of its ends respectively to the agricultural implement and to the tractor, said tractor being remarkable in that it comprises a guiding device according to the invention. CECC01-FR-1_TEXTE REMOVAL_RG-GE - 5 Brief description of the figures Other advantages and characteristics will emerge more clearly from the following description of several variant embodiments, given as non-limiting examples, of a guiding device of a coupled agricultural implement according to the invention, with reference to the drawings in which: - Figure 1 is a schematic top view of a tractor attached to a tractor, - Figure 2 is a schematic top view of an agricultural implement coupled to a tractor equipped with a device for guiding a hitched agricultural implement in accordance with the invention, the hitch being in a first configuration, FIG. 3 is a schematic view from above of a tool agricultural tractor coupled to a tractor equipped with the guiding device of an agricultural implement of Figure 1, the hitch being in a second configuration, - Figure 4 is a schematic top view of a farm implements coupled to a tractor quipé the guiding device of an agricultural tool of Figure 1, the coupling being in a third configuration. BEST WAY OF CARRYING OUT THE TECHNICAL INVENTION With reference to FIG. 1, the hitch 1 of an agricultural implement 2 towed by a tractor 3 is generally of the three-point type. This type of hitch 1, which allows the weight and effort of the agricultural implement 2 to be transferred to the rear wheels of the tractor 3, has several components working together. These include: - a hydraulic system not shown tractor 3 - two lower linkage arms 4 arranged on either side of the vertical sagittal plane of the tractor 3, CECC01-FR-1_TEXT DEPOSE_RG- GE preferably symmetrically and being articulated at one of their free ends to the tractor 3 by means of ball joints 5, - a not shown central arm, also called upper arm, preferably movable, possibly for transmitting to the agricultural tool 2 a rotational movement, - the coupling point 6 of each of said lower linkage arms 4 on the agricultural implement 2, these coupling points 6 being generally of the ball joint type, and 10 - of a stabilizer 7 connecting each of the lower linkage arms 4 to the tractor 3, each stabilizer 7 being articulated at its two ends respectively to its associated lower linkage arm 4 and the tractor 3, and can be either fixed, adjustable or free of type string for example. The lower link arms 4, also called lifting arms, are driven by the hydraulic system of the tractor 3, and allow the raising, lowering and tilting of the agricultural implement 2. Said hydraulic system 20 of the tractor is controlled by the driver of the tractor 3 which usually has adjustment. Each of several coupling point parameters 6 conventionally comprises a not shown clevis provided with orifices in which unrepresented pins are inserted, the latter also being inserted into a not shown orifice of the lower linkage arm. locking is ensured by placing pins at the end of said hitch pin configuration. This lower arm of the ball type. It will be understood that makes it possible to obtain a connection 3 - agricultural tool 1 globally the lower linkage arms 4 articulated at each of their ends then form a quadrilateral which can be deformed in order to move the tool CECC01-FR-1_TEXT DEPOSERG-GE - 7 agricultural 2 relative to the axis of the direction of travel of the tractor 3 to correct its trajectory and therefore its position. This type of hitch 1 to three points may have, depending on the needs and / or types of agricultural tool 1, several configurations. Thus, in a first configuration shown in Figure 2, the lower linkage arms 4 are parallel to each other. In this configuration, when one of the lower link arms 4 is pivoted about a vertical axis at the ball 5, the agricultural implement 1 moves (position shown in dashed line in said figure 1) parallel to its normal position (shown in solid lines in FIG. 1) and therefore the correction is equal to the displacement. Similarly, in a second configuration shown in Figure 3, the lower linkage arms 4 are not parallel to each other and form an open angle. In this configuration, when a lower link arm 4 is pivoted about a vertical axis at the ball 5, the agricultural implement 1 moves (position shown in dashed line in said FIG. ) relative to its normal position (shown in solid lines in said FIG. 2) by pivoting in the opposite direction to the desired direction of travel and therefore the displacement is greater than the desired correction. Finally, in a third configuration shown in Figure 4, the lower linkage arms 4 are not parallel to each other and form a closed angle. In this configuration, when a lower link arm 4 is pivoted about a vertical axis at the ball 5, the agricultural implement 1 moves (position shown in dashed line in said FIG. ) with respect to its normal position (shown in solid line CECC01-FR-1TEXT DEPOSERG-GE - 8 in said FIG. 2) by pivoting in the same direction as the desired direction of travel and consequently the displacement is less important for a correction given. To increase the responsiveness of the correction, the third configuration will be preferable. In order to implement the correction of the trajectory and therefore of the position of the agricultural implement 2 and allow it to be self-aligned with respect to the tractor 3, the invention consists in putting in place a device 10 for guiding the entire vehicle 10 agricultural tool assembly 2 - tractor 3. With reference to FIGS. 1 to 3, this guiding device 10 comprises at least a first GPS antenna 11 disposed on the agricultural implement 2, a second GPS antenna 12 disposed on the tractor 3 and an actuator 13 15 controlled by a distributor not shown enslaved by said first and second GPS antennas 11, 12 through a control station not shown. Said actuator 13 is preferably arranged in place of one of the stabilizers 7 between the tractor 3 and one of the lower link arms 4 and makes it possible to move said lower linkage arm 4 about the axis vertical direction of the ball 5 in order to move the agricultural tool 2 relative to the tractor 3. In addition, this actuator 13 is preferably a double-acting hydraulic cylinder connected to the hydraulic system of the tractor 3 via the distributor. Finally, the actuator 13 is advantageously provided with end stops to indicate that it is in abutment, that the guide device 10 has reached its limit capacity for correcting the trajectory and therefore the position of the agricultural tool 30. 2 and that the tractor driver 3 must intervene by correcting the direction of said tractor 3. The guiding device 10 may also include a terminal advantageously with a touch screen allowing the driver to control the guidance of the driver. tractor 3 by visualizing the main elements such as the real-time accuracy, the sensitivity and the behavior of the agricultural implement 2. Similarly, the guiding device 10 can also be coupled to an automatic control and control device. the direction of the tractor 3 to automatically guide the latter without the intervention of the driver. This type of automatic device is well known to those skilled in the art.
With this configuration, the guiding device 10 perfectly determines in real time the instantaneous positions and the respective trajectories of the agricultural implement 2 and the tractor 3 with the aid of the first and second GPS antennas 11, 12 according to at least the two horizontal axes 15. These data are then transmitted to the control station to, on the one hand, guide the tractor 3 and, on the other hand, automatically align the agricultural implement 2 with respect to the trajectory of said tractor 3 in order to have rectilinear furrows and according to a predetermined map, thus avoiding forgotten areas and overlaps in particular. To obtain this "self-alignment" of the agricultural implement 2, the control station determines the possible correction to be made to the position of the agricultural implement 2 25 according to the position of the tractor 3 and drives the actuator 13 through to the distributor to move said lower link arm 4 about the vertical axis of the ball 5 to move the agricultural implement 2 relative to the tractor 3.
It is well understood that the guide device 10, according to the invention, is particularly simple to implement and that it is adaptable to any type of agricultural implement 2, because it is integral with the hitch 1 of the tractor 3 and not of said agricultural implement 2. CECC01-FR-1TEXTE REMOVAL_RG-GE - 10 - Finally, this guide device 10 is particularly interesting because it allows both the guiding of the tractor 3 and the self-alignment of the agricultural tool 2 in order to obtain a better quality result and increased productivity. DESCRIPTION OF OTHER EMBODIMENTS According to another embodiment not shown, the guide device 10 can also be used without the second GPS antenna 12 disposed on the tractor 3 in the case, for example, where there are already grooves. net drawn in the ground. Indeed, the driver of the tractor 3 then only to follow said grooves. It goes without saying that this embodiment of the guide device 10, certainly more economical, is still less efficient because it requires a ground already prepared. Industrial applicability As previously described, the guide device 10, according to the invention, applies more particularly to an agricultural implement 2 coupled to a tractor 3 equipped with a three-point hitch. It goes without saying that the guide device 10 can also be used for a tractor 3 provided with any other type of hitch such as for example a single-point hitch, the actuator 13 can then be placed between the tractor 3 and the unique hitch arm. Finally, it is clear that the present invention is not limited to the sole embodiment of this guiding device 10; it embraces, on the contrary, all variants of implementation and application respecting the same principle. CECC01-EN-1_TEXT DEPOSERG-GE