GHISLERI, Pier Francesco (Via Mazzini 25, Asola, 46041, IT)
Claims.
1). A method for controlling a trajectory and a speed of a vehicle (1) along a tract (2), comprising following cyclically-repeated stages: detecting at least a first distance (3a, 3b, 3c, 3d) between at least a first point of detection (30) of the vehicle (1) and at least an indicating element (4) of a progress of the tract (2); activating means for controlling the trajectory (5) of the vehicle (1) in order to reduce a difference between the at least a first distance (3a, 3b 3c,3d) and an optimal value for the at least a first distance; wherein it further comprises following stages, also cyclically repeated: detecting a presence of at least a material element (6, 6') internally of a frontal detection zone (60) in front of the vehicle; detecting, subordinately to the detected presence of at least a material element (6, 6') internally of the frontal detection zone (60), at least a frontal distance (61a, 61b) between at least a second detection point (62a, 62b) of the vehicle (1) and any point on the material element (6); identifying, by processing the frontal distances (61a, 61b) detected during at least two successive detection stages, the material element (6, 6') as a morphological element (6') belonging to the road, or as an extraneous element (6); subordinately to a detected presence of at least a material element (6, 6') internally of the frontal detection zone and identification thereof as an extraneous element (6), verifying by means of a comparison between the frontal distances (61a, 61b) detected during at least two detection stages, a possible state of relative nearing between the vehicle (1) and the extraneous element (6); if the relative nearing is confirmed, means for controlling the vehicle (1) are activated in order to prevent an impact between the vehicle (1) and the extraneous element (6).
2). The method of claim 1 , wherein the indicator element (4) of the progress of the road tract presents a striker surface (40) which is continuous and vertical, the first distance (3a, 3b, 3c, 3d) detected being a distance between a first detection point (30) of the vehicle and a point of intersection between a straight line oriented in a lateral detection direction (A) originating in the first point of detection of the vehicle and the striker surface (40). 3). The method of one of the preceding claims, wherein it comprises following stages, subordinated to the detected presence of at least a material element (6, 6') internally of the frontal detection zone (60) and to identification thereof as an extraneous element (6); assess relative speeds of the vehicle (1) and the extraneous element (6) by means of a comparison between the frontal distances (61a, 61b) detected during at least two successive detection stages; transmit the data relating to the relative speeds to the means for controlling the speed of the vehicle (1) to adapt said speed to a speed of the extraneous element (6).
4). The method of claim 3, wherein it comprises a following stage, subordinated to a detected presence of at least a material element (6, 6') internal of the frontal detection zone (60) and identification thereof as an extraneous element (6); transmit the frontal distance (61a, 61b), detected during at least a stage of detection, to the means for controlling the speed in order to reduce a difference between the frontal distance (61a, 61b) and an optimal safety distance.
5). The method of one of the preceding claims, wherein during the stage of detecting at least a frontal distance (61a, 61b), frontal distances detected are two in number: a right-side frontal distance between a second right-side detection point (62a) of the vehicle (1) and an intersection point of a straight line oriented in a right-side detection direction (B) originating in the second right-side detection point (62a) with the detected material element (6, 6'); a left-side frontal distance (61b) between a second left-side detection point (62b) of the vehicle (1) and an intersection point between of a straight line oriented in a left-side detection direction (C) originating in the second leftside detection point (62b) with the detected material element (6, 6'). 6). The method of claim 5, wherein it comprises, between a detection stage of the frontal distances (61a, 61b) and a following detection stage thereof, a stage of varying an orientation of the right-side detection direction (B) and the left-side detection direction (A).
7). The method of claim 6, wherein during stages of varying the orientation of the right-side detection direction (B) and the left-side detection direction (C), projections on a horizontal plane of the directions assume alternatively variable and specular orientations.
8). The method of claim 6 or 7, wherein during the stages of varying the orientation the right-side detection direction (B) and the left-side detection direction (C), the projections of the directions on a vertical plane longitudinal to the vehicle (1) assume alternatively variable and specular orientations. 9). The method of one of the preceding claims, wherein it comprises a following stage, subordinated to a detected presence of at least a material element (6, 6') internally of the frontal detection zone (60) and to identification thereof as a morphological element (6'); activating means for controlling a speed of the vehicle (1) in order to adapt a speed thereof to the presence of the morphological element (6').
10). A vehicle which can be controlled according to the method of one of the preceding claims, wherein it comprises: a lateral distance sensor (31) oriented in a fixed lateral detection direction (A); right-side and left-side frontal distance sensors (63a, 63b), which are mobile and oriented respectively in variable right-side and a left-side frontal detection directions (B, C); means for controlling a trajectory (5) of the vehicle (1) and means for controlling a speed of the vehicle (1); a control unit (7) connected to the distance sensors (31, 63a, 63b) and to the means for controlling the trajectory and the speed of the vehicle (1). |
Description
METHOD FOR CONTROLLING A TRAJECTORY AND SPEED OF A VEHICLE ALONG A PREDEFINED PATH, AND A VEHICLE WHICH CAN BE CONTROLLED BY THE METHOD
Technical Field
The invention relates specifically, though not exclusively, to a process for automatically controlling a trajectory and speed of a motor vehicle predisposed for automatic driving, along a specially-equipped tract of road. The invention also relates specifically but not exclusively to a motor vehicle which can be controlled by the method. Background Art
As is known, road transport of people and goods today is done by autonomous motorisation with driving systems which are directly handled by a person, i.e. the driver of the vehicle. The disadvantages inherent in this system are many and evident. Firstly there is a serious problem of road safety, enormously influenced by the inevitable incidence of human error in a sector where the dynamic development of potentially dangerous situations must be controlled in real time by an operator. Decisional errors, unsuitable physical conditions or driver's moods can result in accidental collisions with damage to people and/or things. A further problem is the mental and physical demand placed on the driver. This makes driving laborious and not reconcilable with other contemporary activities, making it also a time-wasting activity. Finally, high and incoherent traffic flows in many cases lead to a congestion of the road system, with inevitable waste of time and comfort for both drivers and passengers of the vehicles.
The above problems could be largely obviated by an automatic driving system for cars in traffic. Numerous projects have been developed for "automatic motorways" i.e. lengths of road which are equipped for transit of vehicles predisposed for being automatically driven. These road tracts are advantageously provided with equi-distanced magnetic elements identifying the centre of the road. The guide system of the vehicles detects the magnetic elements and the trajectory of the vehicle is corrected on the basis of this. The vehicle driving system also enable regulation of the speed of the vehicle on the basis of the radio-transmitted signals processed by an external controller in consideration of weather and traffic conditions.
The above-described automatic driving method has various drawbacks. A first and main drawback is that the method requires, as can be understood from the above description, tracts of road which are exclusively dedicated to the transport of vehicles predisposed to be controlled according to the method. The presence on the tract of road of fast-moving vehicles which are not regulated by the system radio-transmitted signals would cause obvious and serious dangers of collision. The costs for equipping the road surfaces would be astronomical, as would the costs for equipping the cars in the equipped region. These are the very obvious consequences of the use of the system with road tracts dedicated to automatic driving circulation.
Further drawbacks concern the cost for the arrangement of the magnetic elements on the road lanes, the need to have an external control operator, the inherent risk due to the possible and contemporaneous presence of obstacles not detected by the control operator. The main aim of the present invention is to propose a method for controlling the trajectory and the speed of a vehicle along a predefined course which does not exhibit the drawbacks of the known automatic driving methods.
An advantage of the method of the present invention relates to the fact that it can be applied on tracts not exclusively dedicated to automatically controlled vehicles without this causing risks for road safety on the considered tract of road. Another advantage of the method of the invention relates to the fact that it can be actuated on traditional motorway roads, with limited economic investments and without the need for long times of application.
A further advantage of the method of the present invention is that the trajectory and the speed of the vehicle are controlled according to rigorous safety criteria, at economic speeds and with limited stress on the driver, passengers and the vehicle's mechanical parts.
Disclosure of Invention
Further characteristics and advantages of the invention will better emerge from the detailed description that follows, with reference to the figures of the drawings, which are provided by way of non-limiting example, and in which: figure 1 is a schematic lateral view of a vehicle controlled according to the present method, nearing a considerably hilly tract of road; figure 2 is a schematic view from above of a vehicle, evidencing the elements arranged thereon to enable control thereof by the present method; figure 3 is a view from above of a vehicle controlled according to the present method during the successive stages of negotiating a curve; figure 4 is a view from above of a vehicle controlled according to the present method, preceded by another vehicle; figure 5 is a lateral view of a vehicle controlled according to the present invention, preceded by another vehicle; figure 6 is a schematic lateral view of a vehicle controlled according to the present method, nearing a curved tract of road.
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With reference to the figures of the drawings, 1 denotes a vehicle automatically negotiating a tract 2 of road. According to the present invention, the method for controlling the trajectory and the speed of the vehicle 1 along the tract 2 comprises the stages described hereinunder, cyclically repeated.
At least two stages relate principally to the control of the trajectory of the vehicle; at least a first distance 3a, 3b,3c, 3d must be detected between at least a first detection point 30 on the vehicle 1 and at least an indicating element 4 of the tract 2 and means for controlling the trajectory 5 of the vehicle must be activated in order to reduce the difference between the at least a first distance 3a, 3b,3c, 3d and an optimal value of the at least a first distance. Further stages are mostly involved with the control of the vehicle speed. These stages are as follow: detecting any presence of at least a material element 6, 6' within a frontal detection zone 60 in front of the vehicle; detecting, subordinately to the detected presence of at least a material element 6, 6' within the frontal detection zone 60, at least a frontal distance 61a, 61b between at least a second detection point 62a, 62b of the vehicle and any one point on the material element 6; identifying, by processing the frontal distances 61a, 61b detected in at least two successive stages of detection, the material element 6, 6' as a morphological element of the tract 2 or as an extraneous element 6; subordinately to the detected presence of at least a material element 6, 6' internally of the frontal detection zone and to its identification as an extraneous element 6', identifying, using a comparison between the frontal distances 61a, 61b detected in at least two successive detection stages, any state of relative nearing between the vehicle 1 and the extraneous element 6; finally, when the state of relative nearing is verified,
activating means for controlling the speed of the vehicle 1 in order to prevent any impact of the vehicle 1 with the extraneous element 6. While the first two described stages constitute a retroactive control cycle of the vehicle, the stages that follow describe a retroactive control cycle of the speed in response to the identification of obstacles on the road, and enable the controlled vehicle to be moved on a tract of road which is not exclusively dedicated to tele-directed vehicles, as was the case in the described prior art. In the case of presence of another vehicle within the frontal detection zone 60, the vehicle will be identified as an extraneous element 6, i.e. an element not belonging to the road or not being part of the road furniture, determining a deceleration of the first vehicle in the case of a relative nearing of the two vehicles.
As for the retroactive control cycle of the trajectory, the indicator element 4 of the above-identified tract can exhibit a continuous striker surface 40 which is substantially vertical, i.e. parallel to the road surface. In this case, the first distance 3a, 3b, 3c, 3d detected is the distance between the first detection point 30 of the vehicle and the point of intersection between a straight line going in a lateral detection direction A having its origin in the first detection point 30 of the vehicle and the striker surface 40. In particular, the striker surface 40 can be advantageously defined by a special band, applied to a preexisting guardrail or fixed above any lateral delimiting element of the road, whether made of metal or concrete or the like. At the first detection point 30 the vehicle therefore comprises a lateral distance sensor 31 which can detected, as described, the first distance 3a, 3b, 3c, 3d. The sensor is preferably an optic laser sensor, even though obviously the described method can be actuated using distance sensors of a different type. The lateral distance sensor 31 is oriented in the lateral detection direction A. In the illustrated
embodiment, the first detection point 30 being arranged on a flank of the vehicle, the direction is substantially horizontal and perpendicular to the flank. The height from the ground of the lateral distance sensor 31 is obviously the same as the height from the ground of the striker surface 40. The control action on the means for controlling the trajectory 5, i.e. on the steering wheel of the vehicle, which action is aimed at maintaining the first detected distance 3a, 3b,3c, 3d constant over time, causes a vehicle trajectory which substantially corresponds to the articulation of the tract 2 and the striker surface 40 destined for signalling it. As shown in figure 3, this control action thus enables the vehicle to be kept in lane while negotiating a curve. The above-mentioned retroactive control cycle of the vehicle 1 speed operates, as mentioned, on the means for controlling the speed in a case of a detected presence of a material element 6, 6', identified as an extraneous element 6. In this case, the control method advantageously comprises the further stages of evaluating, through a comparison between the frontal distances 61a, 61b detected during at least two successive detection stages, the relative speed between the vehicle 1 and the extraneous element 6 and to retroactively send the relative speed to the means for controlling the speed in order to adapt the speed of the vehicle 1 to the speed of the extraneous element 6. In this case the process preferably comprises a stage of retroactively adapting the frontal distance 61a, 61b detected during at least a stage of detecting to the means for controlling the speed in order to reduce the difference between the frontal distance 61a, 61b and an optimal safety distance. By making the vehicle speed conform to the speed of the extraneous element 6, in a case in which the extraneous element is in fact a second vehicle moving in a same direction as the first, the first vehicle will get in line behind the second vehicle without halting its progress. Further, by checking
the frontal distance 61a, 61b detected, the first vehicle stays at an optimal safety distance from the second. In the case of a fixed extraneous element 6, which might be a stationary vehicle or another obstacle, the controlled vehicle 1 halts, stopping at an optimal safety distance from the element. During the stage of detecting at least a frontal distance 61a, 61b, the frontal distances detected are preferably at least two in number: a right frontal distance between a second right point of detection 62a of the vehicle 1 and the point of intersection of a line directed along a right detection direction B having its origin in the second right detection point 62a with the material element 6, 6' detected; a left frontal distance 61b between a second left detection point 62b of the vehicle 1 and the point of intersection of a line directed in a left detection direction C originating in the second left detection point 62b with the material element 6, 6' detected. In the previously described stages relating to the frontal distance 61a, 61b detected, the distance is preferably to be understood, in the case of a considerable difference between the various frontal distances detected, as the lowest distance from among the distances.
As with the first detection point, also with the second right and left detection points 62a, 62b the vehicle 1 comprises frontal distance sensors, left and right 63a, 63b, preferably optic laser sensors, which are directed in the corresponding detection directions. The two detection points 62a, 62b are symmetrically arranged on the front part of the vehicle, at a height from the ground which is preferably equal to the height of the lateral distance sensor 31. The stage of identifying the material element 6, 6' as a morphological element 6' of the road or as an element which is extraneous of the road tract responds to a natural requirement of the method of the invention. The frontal
detection zone 60 extends over a wide area in front of the vehicle 1; indicatively the frontal distance sensors 63 a, 63 b can have a maximum detecting distance of about a hundred metres. The frontal detection zone 60 can therefore take in either the asphalt of the road, in a case of a high ascending angle in front of the vehicle 1 , or the lateral striker surface 40 in a case of a curve coming up. These elements, which must not be interpreted as obstacles during the control stages, have been termed morphological elements 6' herein. The distinction between morphological elements 6' and extraneous elements 6 is done, as previously mentioned, by processing the frontal distances 61a, 61b detected during at least two successive stages of detection. To facilitate the distinction, the method of the invention comprises, between a stage of detecting the frontal distances 61a, 61b and the following, a stage of varying the right-side detection direction B and the left-side detection direction C. During the course of the stages of varying the orientation of the right-side detection direction B and the left-side detection direction C, the projections on the horizontal plane as well as the projections of a vertical longitudinal plane of the vehicle 1 of these directions assume alternatively variable and specular orientations. The frontal distance sensors 63a, 63b are effectively rotated, defining elliptical orbits. In a first position, the two detection directions both lie on the horizontal plane and diverge; in a second position, the two detection directions also lie on the horizontal plane but converge; in a third and in a fourth position, the directions are on parallel planes to the longitudinal plane of the vehicle and their projections on the plane diverge. By processing the frontal distances 61a, 61b detected during successive detection stages, a curve in a nearing direction is easily recognised. The difference between the right-side frontal distance 61a and the left-side frontal
distance 61b is in this case large when the frontal distance sensors 63a, 63b are in the first position and detect portions of the striker surface 40 which are distanced, and smaller values when the sensors are in the second position and detect close or coinciding portions of the striker surface 40. The alternating of large and small differences is interpreted by a control unit 7 which indicates a morphological element 6' rather than an extraneous element 6. In the same way, the presence of a rising inclination in front of the vehicle 1 causes considerable differences between the right-side frontal distances 61a and the left-side frontal distances 61b detected at the third and fourth position of the right 61a and left 61b frontal distances detected at the third and fourth position of the frontal distance sensors 63a, 63b, alternated at zero differences at the first and second position of the sensors.
The method can advantageously comprise a stage subordinated to the detected presence of at least a material element 6, 6' internally of the frontal detection zone 60 and identification thereof as a morphological element 6, of activating means for controlling the vehicle 1 speed in order to adapt the speed to the presence of the morphological element 6. This stage is translated into a slowing down of the vehicle 1 in proximity of hills or bends; the deceleration of the vehicle can be inversely proportional, or specially related in another way, to the change in the differences between the frontal distances 61a, 61b, a variation which, as can be evinced from the above description, is in turn dependent on the degree of curvature or inclination of the road. A vehicle 1 controlled according to the present method comprises, as mentioned, a lateral distance sensor 31 orientated in a fixed lateral detection direction A, right-side and left-side frontal distance sensors 63a, 63b, mobile and respectively oriented in variable right-side and left-side frontal detection directions B and C; means for controlling the trajectory 5 and means for
controlling the speed. The vehicle 1 finally comprises at least a control unit 7 connected to the distance sensors 31; 63 a, 63 b and the means for controlling the trajectory 5 and the speed. In a further embodiment of the above-described method, the stages of activating the means of the control of the vehicle 1 speed, both to prevent impact with extraneous elements 6 and to adjust the vehicle speed in the presence of morphological elements 6', are preceded by a stage of acoustically, optically or another way signalling to the vehicle user the need to operate the means for controlling. The stage of signalling can completely replace the stage of automatically activating the means for controlling when it causes an adequate reaction on the part of the user. The stage of signalling enables a driver to gain a gradual contact with the above-described driving system, allowing, during a first stage of operation of the system, a degree of decisional autonomy in the sense of a not-completely automated driving method, but a considerably aided one.