Control method for vehicle

Abstract

A control system (1) for driving a vehicle by automatic steering is a system comprising: a vehicle control unit (112) for controlling the vehicle so that an object point set for the vehicle passes through a prescribed route; an object point selection processing unit (113) for selecting an object point; and an object point update processing unit (114) for updating the object point of the control object at any time by setting the object point newly selected by the object point selection processing unit (113) as a control object. The control system (1) is a highly versatile system capable of automatic steering regardless of the type of vehicle or the shape of the route.

Description

Technical Field

[0001] The present invention relates to a control method and a control system for driving a vehicle by automatic steering. Background Art

[0002] In the past, for example, there is a known navigation system that receives GPS radio waves to locate the vehicle and guides the vehicle to a preset destination (see, for example, Patent Document 1 below). By driving support control such as voice output of the guidance route, the vehicle will not lose its way even when traveling on unfamiliar land, and can efficiently reach the destination.

[0003] Furthermore, for example, a driving support system using 3D map data has been proposed, which three-dimensionally represents the road environment including surrounding buildings, guardrails, signs, curbs, etc. According to the driving support system, for example, by mapping the position of the vehicle onto the 3D map data, a high level of driving support including automatic driving can be achieved. If automatic driving is possible, the driving burden of the vehicle can be reduced.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2001-264076 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, the conventional vehicle system has the following problems: the appropriate travel route varies depending on the type of vehicle to be controlled, the shape of the travel route, etc., and it is difficult to achieve a highly versatile control specification.

[0009] The present invention has been made in view of the above-mentioned conventional problems, and aims to provide a control method and a control system for automatic steering with high versatility.

[0010] Solutions to Solve Problems

[0011] One embodiment of the present invention is a control method for a vehicle, which is a control method for driving the vehicle by automatic steering, wherein:

[0012] The vehicle control method performs:

[0013] a travel control process for controlling the vehicle so that a target point set for the vehicle passes through a prescribed route;

[0014] an object point selection process of selecting a new object point to be set for the object point; and

[0015] The target point updating process updates the target point that is the control target of the travel control process to the new target point selected by the target point selecting process.

[0016] One embodiment of the present invention is a control system for a vehicle, which is a control system for driving the vehicle by automatic steering, wherein:

[0017] The vehicle control system comprises:

[0018] a vehicle control unit configured to control the vehicle so that a target point set for the vehicle passes through a prescribed route;

[0019] an object point selection processing unit that selects a new object point to be set for the object point; and

[0020] The object point update processing unit updates the object point that is a control target of the vehicle control unit to the new object point selected by the object point selection processing unit.

[0021] Effects of the Invention

[0022] The vehicle control method and control system of the present invention are control methods for driving the vehicle by automatically steering the target point set for the vehicle so that the target point passes through the prescribed route. One of the technical features of the present invention is that the new target point set for the target point of the control object is selected and the target point is updated.

[0023] In the control method of the present invention, by updating the object point of the control object, the actual driving route of the vehicle can be adjusted. In the present invention, when adjusting the actual driving route, there is little need to change the control specifications. In this way, the control method and control system of the present invention are highly versatile control methods or control systems that can adjust the driving route of the vehicle without significantly changing the control specifications. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is an illustration of the autonomous driving system.

[0025] Figure 2 This is an illustration of a magnetic marker.

[0026] Figure 3 This is the main view of the RFID tag.

[0027] Figure 4 It is a block diagram showing the system configuration on the vehicle side.

[0028] Figure 5This is an explanatory diagram illustrating the change over time of the magnetometer measurement value in the traveling direction when passing through a magnetic marker.

[0029] Figure 6 This is an explanatory diagram illustrating the distribution of magnetic measurement values ​​in the vehicle width direction obtained by the magnetic sensors Cn arranged in the vehicle width direction.

[0030] Figure 7 This is a diagram illustrating the operation of the automatic driving system.

[0031] Figure 8 This is a diagram for explaining how to determine the position of the vehicle.

[0032] Fig. 9 It is an explanatory diagram showing a deviation ΔD of an object point (host vehicle position) with respect to a target course.

[0033] Fig.10 This is an explanatory diagram of control when a target point at the center of the vehicle width direction is selected.

[0034] Fig.11 This is a diagram showing a control example when a left-facing object point is selected.

[0035] Fig.12 is a graph showing the relationship between the curvature and the correction coefficient D1.

[0036] Fig.13 is a graph showing the relationship between the wheelbase and the correction coefficient D2.

[0037] Fig.14 This is an explanatory diagram of the inner wheel difference when the target point at the center in the vehicle width direction is selected.

[0038] Fig.15 This is an explanatory diagram of the inner circle difference when a left-facing target point is selected.

[0039] Fig.16 This is a diagram for explaining the object point selection process when passing through a sharp curve.

[0040] Fig.17 It is a diagram illustrating an example of a setting screen for setting a preferred vehicle position.

[0041] Fig.18 This is a diagram for explaining the target point selection process when avoiding obstacles.

[0042] Fig.19 This is a diagram for explaining the object point selection process when changing lanes. DETAILED DESCRIPTION

[0043] The embodiments of the present invention will be described in detail using the following examples.

[0044] (Example 1)

[0045] This example is an example of a control method and a control system for driving a vehicle 5 along a preset target route (an example of a predetermined route). Figures 1 to 19 Provide explanation.

[0046] As an example of a control system, an automatic driving system 1 is Figure 1 The structure includes a sensor unit 2 for performing magnetic detection, a tag reader 13 for acquiring marker position information indicating the laying position of the magnetic marker 30, a positioning unit 12 for determining the position of the vehicle, and a driving control unit 11 for controlling the driving of the vehicle 5. The driving control unit 11 can refer to a storage area of ​​a map database (map DB) 110 storing detailed three-dimensional map data (3D map data).

[0047] Below, after briefly explaining (1) the magnetic marker 30 installed on the road, the contents of (2) the sensor unit 2, (3) the tag reader 13, (4) the positioning unit 12, and (5) the travel control unit 11 are explained.

[0048] (1) Magnetic marker

[0049] Magnetic marker 30 such as Figure 1 as well as Figure 2 The magnetic marker 30 is a road marker installed on the road surface 300S. The magnetic marker 30 is arranged along the lanes ( Figure 8 300 in the figure, are arranged at intervals of 10 m in the center of the driving road, for example.

[0050] The magnetic marker 30 is in the shape of a column with a diameter of 20 mm and a height of 28 mm. The magnetic marker 30 is laid in a state of being accommodated in a hole set in the road surface 300S. The magnet constituting the magnetic marker 30 is a ferrite plastic magnet formed by dispersing magnetic powder of iron oxide as a magnetic material in a polymer material as a base material. The maximum energy product (BHmax) of the magnet is 6.4 kJ / m3.

[0051] Table 1 shows a part of the specifications of the magnetic marker 30 of this example.

[0052] [Table 1]

[0053] Magnet Type Ferrite Plastic Magnets diameter φ20mm high 28mm Surface magnetic flux density Gs 45mT

[0054] The magnetic marker 30 exerts a magnetic flux density of 8 μT (micro Tesla) at a height of 250 mm, which is the upper limit of the range of 100 to 250 mm assumed as the installation height of the sensor unit 2. In the magnetic marker 30, the surface magnetic flux density Gs indicating the magnetic intensity at the surface is 45 mT.

[0055] In the magnetic marker 30 of this example, Figure 2 as well as Figure 3 Thus, the RFID (Radio Frequency IDentification) tag 35 that outputs information wirelessly is attached to the end surface that becomes the upper surface. The RFID tag 35 is operated by wireless external power supply, and transmits the marker position information, that is, position data, indicating the laying position of the magnetic marker 30.

[0056] Here, as mentioned above, the magnetic marker 30 is a magnet made by dispersing magnetic powder of iron oxide in a polymer material. For this magnet, the conductivity is low, and it is difficult to generate eddy currents during wireless power supply. Therefore, the RFID tag 35 attached to the magnetic marker 30 can efficiently receive the power transmitted wirelessly.

[0057] The RFID tag 35 is, for example, a tag sheet 350 ( Figure 3 ) is mounted on the surface of the label sheet 350. A printed pattern of a loop coil 351 is provided on the surface of the label sheet 350. The loop coil 351 functions as a power receiving coil that generates an excitation current by electromagnetic induction from the outside and as a transmitting antenna for wirelessly transmitting position data and the like.

[0058] (2) Sensor unit

[0059] Sensor unit 2 Figure 1 as well as Figure 4 The sensor unit 2 is a rod-shaped unit formed by integrating the magnetic sensor array 21 as a magnetic detection unit and the IMU (Inertial Measurement Unit) 22 for inertial navigation. The sensor unit 2 is installed opposite to the road surface 300S in the vehicle width direction. For example, for the sensor unit 2 installed on the inner side of the front bumper of the vehicle 5, the installation height based on the road surface 300S is 200 mm.

[0060] Magnetic sensor array 21 ( Figure 4) is provided with 15 magnetic sensors Cn (n is an integer from 1 to 15) arranged in a straight line and a detection processing circuit 212 having a built-in CPU, etc., not shown. In the rod-shaped sensor unit 2, the 15 magnetic sensors Cn constituting the magnetic sensor array 21 are arranged at intervals of 10 cm along the length direction. When the magnetic sensor array 21 is installed along the vehicle width direction of the vehicle 5, the 15 magnetic sensors Cn are arranged along the vehicle width direction. In the structure of this example, the magnetic sensor C1 is located on the left side of the vehicle 5 (the driver's seat side of a left-hand drive vehicle), and the magnetic sensor C15 is located on the right side of the vehicle 5 (the passenger seat side of the vehicle) (refer to Fig.10 . ).

[0061] The magnetic sensor Cn is a sensor that detects magnetism by utilizing the well-known MI effect (Magnet Impedance Effect) that the impedance of a magnetically sensitive body such as an amorphous wire changes sensitively in response to an external magnetic field. The magnetic sensor Cn has magnetic sensitivity in the longitudinal direction of the amorphous wire.

[0062] In the magnetic sensor Cn of this example, a non-illustrated magnetically sensitive body such as an amorphous wire is arranged along two orthogonal axial directions. The magnetic sensor Cn can detect the magnetism acting on the two orthogonal axial directions. It should be noted that in the sensor unit 2 of this example, when installed on the vehicle 5, the magnetic sensor Cn is assembled in a manner that can detect the magnetic components in the traveling direction and the vehicle width direction.

[0063] The magnetic sensor Cn is a highly sensitive sensor having a magnetic flux density measurement range of ±0.6 mT and a magnetic flux resolution within the measurement range of 0.02 μT. In this example, the frequency of magnetism measurement by each magnetic sensor Cn of the sensor unit 2 is set to 3 kHz to cope with high-speed vehicle travel.

[0064] Table 2 shows part of the specifications of the magnetic sensor Cn.

[0065] [Table 2]

[0066] Measuring range ±0.6mT Flux resolution 0.02μT Sampling frequency 3kHz

[0067] As described above, the magnetic marker 30 can act on a magnetic flux density of 8 μT or more in the range of 100 to 250 mm assumed as the installation height of the magnetic sensor Cn. If the magnetic marker 30 acts on a magnetic flux density of 8 μT or more, it can be detected with high reliability using the magnetic sensor Cn with a magnetic flux resolution of 0.02 μT.

[0068] The detection processing circuit 212 of the magnetic sensor array 21 ( Figure 4 ) is performed to detect the magnetic marker 30 ( Figure 1) is an operation circuit for marker detection processing, etc. The detection processing circuit 212 is composed of memory elements such as ROM (read only memory) and RAM (random access memory) in addition to a CPU (central processing unit) that performs various operations.

[0069] The detection processing circuit 212 obtains the sensor signal output by each magnetic sensor Cn at a frequency of 3kHz and performs a marker detection process. The detection processing circuit 212 inputs the detection result of the marker detection process to the positioning unit 12. In the marker detection process, in addition to the detection of the magnetic marker 30, the lateral offset amount of the object point of the vehicle 5 relative to the magnetic marker 30 is measured, and details of this are described later.

[0070] IMU22( Figure 4 ) is an inertial navigation unit that estimates the relative position of the vehicle 5 by inertial navigation. The IMU 22 has a biaxial magnetic sensor 221 as an electronic compass for measuring the orientation, a biaxial acceleration sensor 222 for measuring acceleration, and a biaxial gyroscope sensor 223 for measuring the angular velocity around the yaw axis. Here, the yaw axis is an axis in the vertical direction. The IMU 22 calculates the displacement by measuring the second-order integral of the acceleration, and calculates the orientation of the vehicle 5 by measuring the integral of the angular velocity. The IMU 22 inputs the calculated displacement and orientation to the positioning unit 12.

[0071] (3) Tag reader

[0072] Tag reader 13 ( Figure 4 ) is a communication unit that communicates with the RFID tag 35 attached to the end surface of the magnetic marker 30 by wireless. The tag reader 13 transmits the power required for the operation of the RFID tag 35 by wireless transmission, and receives the position data sent by the RFID tag 35. The position data, which is an example of the marker position information, is data indicating the laying position (absolute position) of the corresponding magnetic marker 30.

[0073] (4) Positioning unit

[0074] Positioning unit 12( Figure 4 ) is a unit that controls the sensor unit 2 and the tag reader 13 and determines the position of the vehicle in real time, which is the position of the target point (appropriately referred to as the vehicle target point) set for the vehicle 5. The positioning unit 12 inputs the position of the vehicle to the driving control unit 11 that controls the driving of the vehicle 5.

[0075] The positioning unit 12 has an electronic substrate (not shown) on which memory elements such as ROM and RAM are installed in addition to a CPU that performs various operations. The method by which the positioning unit 12 determines the position of the vehicle is different when the vehicle 5 reaches the magnetic marker 30 and when the vehicle 5 is located between adjacent magnetic markers 30. In the former case, the positioning unit 12 determines the position of the vehicle based on the position data (marker position information) received from the RFID tag 35. On the other hand, in the latter case, the relative position of the vehicle 5 estimated by inertial navigation is used to determine the position of the vehicle (details are described later).

[0076] (5) Driving control unit

[0077] Driving control unit 11( Figure 4 ) is a unit that controls the vehicle 5, for example, to realize automatic driving to a destination set by the driver. The driving control unit 11 includes: a route data generating unit 111 that generates route data indicating a target route; a vehicle control unit 112 that controls the vehicle 5; an object point selection processing unit 113 that selects an object point set for the vehicle 5; and an object point update processing unit 114 that updates the object point of the control object.

[0078] A map database (map DB) 110 storing detailed three-dimensional map data (3D map data) is connected to the driving control unit 11. A steering operation unit 151, an engine accelerator 152, a brake actuator 153, and the like are controllably connected to the driving control unit 11.

[0079] The driving control unit 11 includes an electronic substrate on which a memory device such as a CPU, ROM, and RAM (not shown) and an I / O chip for inputting and outputting with the outside are mounted. The driving control unit 11 realizes the functions of the above-mentioned components 111 to 114 by, for example, the CPU executing a program read from the ROM. In addition, data on vehicle specifications such as the vehicle width, which is the dimension of the lateral width of the vehicle 5, and the wheelbase, which is the distance between the front and rear axles, are stored in the storage area of ​​the ROM.

[0080] Next, (A) marker detection processing, (B) travel control processing, and (C) target point selection processing of this example will be described.

[0081] (A) Marker detection and processing

[0082] The marker detection process is a process executed by the magnetic sensor array 21. As described above, the magnetic sensor array 21 executes the marker detection process at a frequency of 3 kHz using the magnetic sensors Cn.

[0083] As described above, the magnetic sensor Cn can measure the magnetic component in the traveling direction and the vehicle width direction of the vehicle 5. For example, when the magnetic sensor Cn moves along the traveling direction and passes directly above the magnetic marker 30, the magnetic measurement value in the traveling direction is as follows: Figure 5 In this way, the positive and negative values ​​are reversed before and after the magnetic marker 30 and the position directly above the magnetic marker 30 changes with time. When the magnetic measurement value of the traveling direction detected by any magnetic sensor Cn generates a zero crossing Zc with a positive and negative reversal, it can be determined that the sensor unit 2 (magnetic sensor array 21) is located directly above the magnetic marker 30. When the sensor unit 2 is located directly above the magnetic marker 30 and a zero crossing of the magnetic measurement value of the traveling direction is generated, the detection processing circuit 212 determines that the magnetic marker 30 is detected.

[0084] In addition, for example, regarding a magnetic sensor of the same specification as the magnetic sensor Cn, it is assumed that the magnetic sensor Cn moves along an imaginary line in the vehicle width direction passing directly above the magnetic marker 30. In this case, the magnetic measurement value in the vehicle width direction changes in a manner that the positive and negative are reversed on both sides of the magnetic marker 30 and crosses zero at the position directly above the magnetic marker 30. Therefore, in the magnetic sensor array 21 in which 15 magnetic sensors Cn are arranged in the vehicle width direction, the magnetic measurement value in the vehicle width direction detected by the magnetic sensor Cn is different in positive and negative depending on which side it is located across the magnetic marker 30 ( Figure 6 ).

[0085] In the example of the magnetic measurement values ​​of the magnetic sensors Cn in the vehicle width direction, Figure 6 In the distribution of FIG. 1 , the zero crossing Zc of the magnetic meter measurement value in the vehicle width direction with the positive and negative reversal appears corresponding to the magnetic marker 30. The position of the zero crossing Zc in the distribution of the figure indicates the position of the magnetic marker 30 in the vehicle width direction. The position of the magnetic marker 30 in the vehicle width direction can be determined, for example, as the middle position of two adjacent magnetic sensors Cn separated by the zero crossing Zc, or the position directly below the magnetic sensor Cn where the magnetic meter measurement value in the vehicle width direction is zero and the magnetic meter measurement values ​​of the two outer magnetic sensors Cn are reversed.

[0086] The detection processing circuit 212 measures the deviation of the target point of the vehicle 5 relative to the vehicle width direction of the magnetic marker 30 as the lateral offset. For example, when the center of the vehicle 5 in the vehicle width direction is selected as the target point, the position of the magnetic sensor C8 in the center of the sensor unit 2 becomes the target point. Figure 6In this case, the position of the zero crossing Zc corresponding to the magnetic marker 30 becomes the position of C9.5 which is equivalent to the middle of C9 and C10. As mentioned above, the interval between the magnetic sensors C9 and C10 is 10 cm, so the lateral offset of the object point (magnetic sensor C8) of the vehicle 5 relative to the magnetic marker 30 becomes (9.5-8)×10=15 cm. The example in this figure is an example of the case where the vehicle 5 is on the left side of the lane. It should be noted that for the positive and negative of the lateral offset, the case where the object point of the vehicle is on the left side of the magnetic marker 30 is set to positive, and the case where the object point of the vehicle is on the right side of the magnetic marker 30 is set to negative.

[0087] (B) Driving control processing

[0088] Next, refer to Figure 7 etc. to explain the overall operation of the automatic driving system 1.

[0089] In the automatic driving system 1, the driver can set a destination using, for example, a vehicle monitor such as a touch panel, a voice input system, etc. When the driving control unit 11 obtains the destination input by the driver (S101), it refers to the 3D map data stored in the map DB 110 and performs a path calculation to generate route data (S102).

[0090] Here, the route data is data indicating a target route 1R passing through a target point of the vehicle 5 during the automatic driving control. Figure 8 As shown in the target route 1R, the route data is data connected to the location (absolute position) in the center of the lane 300. In the structure of this example, the magnetic marker 30 is arranged along the center of the lane 300. Therefore, the target route 1R represented by the route data is consistent with the laying line of the magnetic marker 30.

[0091] In the automatic driving control, the vehicle 5 is controlled so that the object point of the vehicle 5 passes through the target route 1R (prescribed route). It should be noted that the object point of the vehicle 5 is updated at any time during the execution of the automatic driving control. The vehicle position in the following description refers to the absolute position of the object point in the setting.

[0092] In the control of the automatic driving, the positioning unit 12 controls the sensor unit 2 to repeatedly perform the above-mentioned marker detection process (S201). When the magnetic marker 30 is detected (S202: Yes), the positioning unit 12 obtains the lateral offset of the object point relative to the magnetic marker 30, and obtains the marker position information (position data) of the RFID tag 35 (S223).

[0093] The positioning unit 12 determines the position of the vehicle as the position offset by an amount corresponding to the lateral offset amount with respect to the laying position of the magnetic marker 30 indicated by the position data (by Figure 8 Here, the lateral offset is the lateral offset of the object point of the vehicle 5 relative to the magnetic marker 30. In addition, the vehicle position is the absolute position of the object point of the vehicle 5.

[0094] On the other hand, when the vehicle 5 is located between adjacent magnetic markers 30 and the magnetic marker 30 cannot be detected (S202: No), the positioning unit 12 estimates the vehicle 5 relative to the most recent vehicle position determined when the magnetic marker 30 is detected ( Figure 8 Specifically, the positioning unit 12 estimates the relative position by integrating the displacements obtained in the same manner along the orientation of the vehicle 5 obtained from the IMU 22.

[0095] The positioning unit 12 is as follows Figure 8 As shown in the example, the most recent vehicle position ( Figure 8 The position marked with × obtained by adding the relative position to the position marked with Δ in the figure) is determined as the position of the vehicle. It should be noted that the arrow in the figure is an example of a vector indicating the relative position. Here, as mentioned above, the position of the vehicle marked with Δ in the figure is the absolute position of the object point of the vehicle 5. In addition, the position of the vehicle marked with × obtained by adding the relative position to the position of the vehicle marked with Δ in the figure also becomes the absolute position of the object point of the vehicle 5. The positioning unit 12 calculates the determined position of the vehicle ( Figure 8 The position of the Δ mark or the × mark in the image is input to the driving control unit 11.

[0096] When the driving control unit 11 obtains the position of the vehicle, it determines the position of the vehicle in the target route 1R. Then, the driving control unit 11 determines the route shape in front of the vehicle 5 (S103). The driving control unit 11 determines, for example, the curvature of the curve in front as the specification of the shape of the route in front of the vehicle 5, that is, the route specification. Here, the route shape in front refers to the route shape a few meters ahead of the vehicle 5. It should be noted that the route shape may be replaced by the route shape of a few tens of meters ahead, or the route shape of the place where the vehicle 5 arrives (zero meters ahead). For example, when the route shape is determined at a nearby place, the route shape is determined when it is estimated that the place has arrived.

[0097] The driving control unit 11 selects a new object point using the route specification and the vehicle specification stored in the ROM (S104, object point selection processing). In the object point selection processing, for example, a position reflecting the route specification such as the curvature of the curve and the vehicle specification such as the vehicle width and wheelbase is selected as the new object point. It should be noted that the new object point may also be selected by considering only one of the route specification and the vehicle specification. It should be noted that the content of the object point selection processing will be described in detail later.

[0098] The driving control unit 11 updates the object point of the control object using the object point newly selected in step S104 (S105, object point update processing). Then, the driving control unit 11 updates the object point of the control object according to the updated new object point. Fig. 9 The deviation ΔD from the target route 1R is calculated in this manner ( S106 ). Then, the driving control unit 11 performs vehicle control such as steering control and accelerator control so as to bring the deviation ΔD close to zero, thereby realizing automatic driving ( S107 ).

[0099] Here, the target route 1R represented by the route data of this example represents the position in the center of the lane 300 forming the driving path, that is, the position on the laying line of the magnetic marker 30. For example, if the position of the magnetic sensor C8 corresponding to the center in the vehicle width direction is set as the target point 1S, then Fig.10 In this way, the vehicle 5 is controlled to travel along the center of the lane 300. In addition, for example, if the position of the left magnetic sensor C3 is set as the target point 1S, Fig.11 In this way, the vehicle is controlled so as to travel on the right side in lane 300 .

[0100] (C) Object point selection process

[0101] Figure 7 The object point selection process of step S104 in is a process for selecting the object point of the vehicle 5. In the object point selection process of this example, any position on the straight line where the 15 magnetic sensors C1 to C15 (Cn) are arranged is selected as the object point. The object point may be, for example, the middle position between adjacent magnetic sensors such as C9.5. In the following description, the position of the object point is expressed as the position of the magnetic sensor C8, the position of the magnetic sensor C2, etc.

[0102] In the automatic driving system 1 of this example, a correction coefficient ( Fig.12 , Fig.13 ). Fig.12 The correction coefficient D1 is a correction coefficient according to the curvature of the curve (an example of a route specification). Fig.13 The correction coefficient D2 is a correction coefficient corresponding to the wheelbase (an example of vehicle specifications). Fig.12 as well as Fig.13 Thus, the values ​​of the correction coefficients D1 and D2 increase as the vehicle width W increases. This is because the necessity of correcting the target point increases as the vehicle width W increases.

[0103] In the target point selection process, for example, a new target point is selected by the calculation of the following mathematical formula 1.

[0104] [Number 1]

[0105] (New target point) = (Initial target point) ± (D1×D2)

[0106] The initially set object point in mathematical formula 1 is, for example, an object point suitable for a straight road, and is set to, for example, the position of the magnetic sensor C8 corresponding to the center of the vehicle 5. When the position of the magnetic sensor C8 is the initially set object point, the value of (the initially set object point) in mathematical formula 1 becomes 8. In addition, when, for example, a value of 3 is calculated as (a new object point) by mathematical formula 1, the position of the magnetic sensor C3 is selected as the new object point.

[0107] In Mathematical Formula 1, the "±" of (D1×D2) as a correction amount is switched to be added or subtracted to the initially set object point, depending on whether it is a left curve or a right curve. In the case of a left curve, considering the inner wheel difference, it is necessary to move the vehicle 5 to the right side in the lane. Therefore, in the case of a left curve, it is preferable to subtract the correction amount from the initially set object point so that an object point on the left can be selected. In this case, the above-mentioned Mathematical Formula 1 becomes (initial set object point)-(D1×D2). On the other hand, in the case of a right curve, considering the inner wheel difference, it is necessary to move the vehicle 5 to the left side in the lane. Therefore, in the case of a right curve, it is preferable to add the correction amount to the initially set object point so that an object point on the right can be selected. In this case, the above-mentioned Mathematical Formula 1 becomes (initial set object point)+(D1×D2).

[0108] According to the above-mentioned mathematical formula 1, it is possible to calculate an appropriate object point according to whether the route ahead (how many meters ahead) is straight or curved. For example, when the route ahead is a straight line, the curvature is almost zero, so the correction coefficient D1 becomes almost zero. Therefore, when the route ahead is a straight line, regardless of the value of the correction coefficient D2, the correction amount becomes almost zero, and an object point located near the initially set object point is selected. On the other hand, when the route ahead is a curve, the correction coefficient D1 becomes a large value, and the correction amount becomes a large amount. Thus, an object point located at a position far from the initially set object point is selected.

[0109] Thus, the object point selection process based on the above-mentioned mathematical formula 1 is as follows: when the route ahead is a straight line, no correction of the object point is performed, and when the curvature of the curve ahead is large, the degree of correction of the object point becomes stronger. It should be noted that the degree of correction also varies according to the vehicle width W. The larger the vehicle width W, the larger the correction coefficients D1 and D2 (refer to Fig.12 as well as Fig.13 . ), so the degree of correction becomes stronger.

[0110] Here, the significance of the correction target point will be described by taking a case where the vehicle 5 passes through a sharp left curve as an example. Fig.14 The figure shows the inner wheel difference generated when passing a sharp left curve with the target point set to the position of the magnetic sensor C8. When driving on a sharp left curve with the target point of the magnetic sensor C8 being suitable for a straight road, the left rear wheel is too far inside due to the inner wheel difference, and the space S inside the curve becomes insufficient. On the other hand, if Fig.15 By setting the target point to the position of the magnetic sensor C2 on the left, the vehicle 5 can travel in a wide right curve in the lane of the left curve. In this case, the left rear wheel will not be too far inside, and the space S on the inside of the curve can be fully ensured.

[0111] In the object point selection process based on the above-mentioned mathematical formula 1, when on a straight road, for example, the object point near the position of the magnetic sensor C8, which is the initial setting object point, is selected as the object point. On the other hand, when on a left curve, an object point to the left of the position of the magnetic sensor C8 is selected by correction. Fig.16 When the path is determined, first, in the straight section, the position of the magnetic sensor C8 is selected as the object point. In the subsequent curved section, the position of the magnetic sensor C2 and the like on the left is selected as the object point. In the straight section, if the position of the magnetic sensor C8 in the center is selected as the object point, the position of the vehicle 5 in the lane will not be offset. In the curved section, if, for example, the magnetic sensor C2 and the like on the left are selected as the object point, the left rear wheel on the inner side of the curve will not be too far inside.

[0112] In this way, if the target point is selected by the target point selection process of the above-mentioned mathematical formula 1, the position of the vehicle 5 in the lane when traveling straight can be appropriately maintained, and the trajectory of the left rear wheel on the inner side of the curve can be made good. The trajectory RG of the left rear wheel of the vehicle 5 is as follows: Fig.16 In this way, a good trajectory is obtained by combining the portion of the left rear wheel trajectory R8 corresponding to the straight section when the target point is the position of the magnetic sensor C8 and the portion of the left rear wheel trajectory R2 corresponding to the curve section when the target point is the position of the magnetic sensor C2.

[0113] In the object point selection process of this example, the correction coefficient D2 ( Fig.13 ) is larger. According to the correction coefficient D2, for a large vehicle with a long wheelbase, the degree of correction of the object point can be increased compared with a small vehicle. As a result, the driving route of a large vehicle with a larger inner wheel difference than a small vehicle when passing through a sharp curve can be made into a larger curve, and the trajectory of the rear wheel on the inner side of the curve can be made good.

[0114] As described above, the automatic driving system 1 of this example is a system that drives the vehicle 5 by automatic steering so that the target point of the vehicle 5 passes through the target route 1R. One of the technical features of the automatic driving system 1 is that the target point of the control object is selected and updated at any time.

[0115] In the automatic driving system 1, by updating the object point of the control object, the actual driving route of the vehicle 5 can be adjusted. In the automatic driving system 1, when adjusting the actual driving route of the vehicle 5, there is less need to change the control specifications and the target route. The automatic driving system 1 can adjust the actual driving route of the vehicle 5 without changing the control specifications and the target route, and can be applied to various vehicle models and driving roads with high versatility.

[0116] It should be noted that in this example, the curvature of the curve is illustrated as a route specification. The route specification may also include lane width and lane type. This is because the narrower the lane width, the more accurately the position of the vehicle in the lane needs to be controlled. The types of lanes include expressways or ordinary roads, outer lanes or inner lanes of a single-sided double lane, and the like.

[0117] It should be noted that the position of the vehicle 5 in the lane is usually the center, but there are drivers who prefer the position to the left or the right. Therefore, a setting screen 50 ( Fig.17 ) is displayed on the vehicle monitor. In the setting screen 50, the vehicle position can be adjusted using the right-pointing triangle mark 50R and the left-pointing triangle mark 50L, and the preferred vehicle position can be set by operating the decision button 52. Preferably, the position of the object point is corrected according to the preferred touch position of the vehicle set using the setting screen 50. The vehicle monitor in this structure is an example of an operating unit for the driver to operate in order to adjust the position of the vehicle in the vehicle width direction on the driving path. Preferably, the driving control unit 11, which serves as an object point selection processing unit, adjusts the object point to the left (right) when the driver operates the operating unit to select a position to the left (right). As this adjustment, for example, it is possible to offset the object point selected by the above-mentioned object point selection processing by a specified amount, or offset the object point initially set in the above-mentioned mathematical formula 1 by a specified amount.

[0118] Furthermore, the position of the vehicle that the driver prefers can be learned based on the position of the vehicle during manual driving, etc. Furthermore, the position of the vehicle that the driver prefers can be learned differently for each type of road. In this case, the driving control unit can select the target point in detail using the learning result of the driver's preference for each type of road. If the target point is selected according to the driver in this way, the driving route of the vehicle 5 based on automatic driving can be made close to the driving route when the driver is driving, and the discomfort that the driver may feel during automatic driving can be reduced.

[0119] In this example, a structure is shown in which any position on a straight line where 15 magnetic sensors Cn are arranged is selected as the target point of the vehicle. Instead of this structure, the target point may be selected two-dimensionally in a horizontal plane parallel to the road surface. In this case, the target point may be selected regardless of whether it is the inside or outside of the vehicle. For example, Fig.18 In this way, even when another vehicle 59 appears and parks on the travel path forming the target route 1R, the target point 1S can be selected outside the vehicle 5. In this case, the parked vehicle 59 can be avoided by normal automatic driving control without switching to a special control for avoiding the parked vehicle 59. For example, if the target point outside the vehicle 5 is selected by the target point selection process, a lane change can be performed to overtake a preceding vehicle traveling in a lane involved in the target route 1R.

[0120] According to the structure of this example, by selecting the object point 1S of the control object, it is possible to perform control to avoid obstacles on the target route 1R, control to perform lane change, etc. At this time, if the object point 1S located outside the vehicle 5 is selected, lateral control with a lateral displacement amount of the vehicle width or more than half of the vehicle width can be performed. For example, Fig.19 In this way, when a lane change is performed to avoid an obstacle such as a preceding vehicle 591 on the route, the object point 1S of the control object can be located at a position overlapping with the preceding vehicle 591, or can be located in another lane 300 adjacent to the lane 300 where the vehicle 5 is located. By selecting the object point 1S of the control object in this way, the lateral control of the vehicle 5 can be achieved.

[0121] It should be noted that the correction coefficient D1 ( Fig.12 ) and adopts a correction coefficient D3 whose value increases according to the steering angle of the steering wheel, or adopts a correction coefficient D3 whose value increases according to the steering angle of the steering wheel in addition to the correction coefficient D1. When the correction coefficient D3 is adopted in addition to the correction coefficient D1, a new target point can be selected by the calculation of the following mathematical formula 2.

[0122] [Number 2]

[0123] (New target point) = (Initial target point) ± (D1×D2×D3)

[0124] The specific examples of the present invention are described in detail above as in the embodiments, but these specific examples are only examples of the technology included in the technical solution. Of course, the technical solution should not be interpreted restrictively by the structure, numerical value, etc. of the specific example. The technical solution includes the technology formed by variously deforming, changing or appropriately combining the specific examples using the known technology, the knowledge of those skilled in the art, etc.

[0125] Description of reference numerals:

[0126] 1. Autonomous driving system (control system)

[0127] 1R Target route (specified route)

[0128] 1S Object point

[0129] 11 Driving control unit

[0130] 12 Positioning unit

[0131] 13 Tag Reader

[0132] 110 Map Database (Map DB)

[0133] 111 Route data generation unit

[0134] 112 Vehicle Control Unit

[0135] 113 Object point selection processing unit

[0136] 114 object point update processing unit

[0137] 2 sensor units

[0138] 21 Magnetic sensor array

[0139] 212 detection processing circuit

[0140] 22IMU

[0141] 30 Magnetic Marker

[0142] 35RFID tags

[0143] 5 vehicles.

Claims

1. A control method for a vehicle, which is a control method for driving the vehicle by automatic steering, wherein: The vehicle control method performs: a travel control process for controlling the vehicle so that the target point set for the vehicle passes through a predetermined route; an object point selection process for selecting a new object point to be set for the object point; as well as an object point updating process for updating the object point that is a control object of the travel control process to the new object point selected by the object point selecting process, Thus, the vehicle control method can adjust the route actually traveled by the vehicle relative to the prescribed route. The object point selection process is a process of selecting the new object point by correcting the initially set position of the object point. The correction amount of the initially set position of the target point based on the target point selection process is obtained by multiplying a correction coefficient D1 representing a route specification as a specification on the shape of the predetermined route and a correction coefficient D2 representing a vehicle specification as a specification of the vehicle.

2. The vehicle control method according to claim 1, wherein: The predetermined route is a route along a lane divided by left and right lane markings on a road, and is a route determined according to the shape of the road.

3. The vehicle control method according to claim 1, wherein: The target point selection process is a process of selecting a position reflecting at least one of a route specification that is a specification on the shape of the predetermined route and a vehicle specification that is a specification of the vehicle as the new target point.

4. The vehicle control method according to claim 1, wherein: The correction coefficient D1 is a correction coefficient corresponding to the curvature of the predetermined route, and the correction coefficient D2 is a correction coefficient proportional to the wheelbase of the vehicle.

5. The vehicle control method according to claim 1, wherein: The correction coefficient D1 is a coefficient that becomes zero when the predetermined route is a straight road.

6. The vehicle control method according to claim 1, wherein: The correction coefficient D1 is a coefficient that varies depending on the lane width and the type of lane.

7. The vehicle control method according to claim 1, wherein: The correction coefficient D2 is a coefficient that varies according to the vehicle width.

8. The vehicle control method according to any one of claims 1 to 7, wherein: The target point selection process can select the new target point for avoiding an obstacle on the predetermined route or for changing a lane during driving.

9. The vehicle control method according to claim 8, wherein: The target point selection process can select a position outside the vehicle as the new target point.

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