Vehicle travel control device and travel control method

Abstract

To enable adjustment of acceleration of own vehicle according to acceleration responsiveness for each vehicle type of a preceding vehicle in a case of causing own vehicle to travel following the preceding vehicle while maintaining an intervehicle distance according to acceleration of the preceding vehicle.SOLUTION: A travel control device includes: a preceding vehicle type determination part that determines whether a preceding vehicle is of a first vehicle type or a second vehicle type by using a vehicle-mounted sensor; and an acceleration control part that switches between first control with respect to acceleration of own vehicle when the preceding vehicle is of the first vehicle type and second control with respect to acceleration of own vehicle when the preceding vehicle is of the second vehicle type.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle driving control device and a driving control method. [Background technology]

[0002] Various technologies have been developed to reduce the burden on drivers and to support safe driving. One well-known example is adaptive cruise control (ACC), which maintains a constant distance between the vehicle and the vehicle ahead. ACC uses on-board sensors and an on-board computer (such as an ECU) to automatically operate the accelerator and brakes, enabling "follow-up driving," which maintains a constant distance between the vehicle and the vehicle ahead.

[0003] Patent Document 1 discloses a cruise control device that improves responsiveness to the acceleration of a preceding vehicle when following a vehicle in a traffic jam. When the preceding vehicle accelerates during following a traffic jam, the cruise control device sets a target acceleration according to the acceleration of the preceding vehicle and controls the acceleration of the host vehicle based on the target acceleration.

[0004] In addition, technology has been developed that receives information about the preceding vehicle (such as acceleration information about the preceding vehicle) via wireless communication and controls the acceleration of the vehicle to follow the preceding vehicle. Technology has also been developed that controls the deceleration of the vehicle by setting a cooperative deceleration rate based on deceleration information obtained through communication with other vehicles. Furthermore, technology has been developed that determines the jerk (rate of change in acceleration) according to the vehicle's surroundings and control status during autonomous driving control to control the vehicle's behavior. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-26226 Summary of the Invention [Problem to be solved by the invention]

[0006] In the current road traffic environment, in addition to engine vehicles (gasoline vehicles, fuel cell vehicles, etc.) that have internal combustion engines driven by fuel (gasoline, hydrogen, etc.), a variety of vehicle types are on the roads, including hybrid vehicles that have two power sources (engine and electric motor), and electric vehicles (EVs) that have batteries and electric motors. Furthermore, even within the same vehicle type, there are vehicles with different acceleration and deceleration performance.

[0007] However, conventional ACCs perform acceleration control regardless of the type of vehicle ahead. With such conventional ACCs, if the host vehicle and the preceding vehicle are the same type of vehicle (such as an internal combustion engine vehicle or an electric vehicle), there is no significant difference in the acceleration response between the two, and the host vehicle's ACC allows it to follow the preceding vehicle.

[0008] On the other hand, when the vehicle type of the host vehicle and the preceding vehicle are different and there is a significant difference in acceleration response, it may be difficult to maintain a constant inter-vehicle distance using a conventional ACC that performs acceleration control without distinguishing between the vehicle type of the preceding vehicle. For example, if the host vehicle is an engine vehicle and the preceding vehicle is an EV vehicle, and the ACC of the host vehicle performs acceleration control that is suitable for following the engine vehicle, it is difficult to maintain a constant inter-vehicle distance by controlling the acceleration of the host vehicle to follow the acceleration of the preceding vehicle, because the acceleration response of the EV vehicle is better than that of the engine vehicle.

[0009] Specifically, EVs have better acceleration response (the response time from when the driver presses the accelerator pedal until the actual acceleration occurs) than gasoline-engine vehicles. Therefore, if the acceleration of the host vehicle (engine vehicle) is controlled according to the acceleration of the preceding vehicle (EV vehicle), the host vehicle will not accelerate quickly in response to the acceleration of the preceding vehicle, making it difficult to maintain passenger comfort during acceleration.

[0010] As described above, when the preceding vehicle has better acceleration response than the host vehicle, it is difficult to appropriately control the acceleration of the host vehicle while maintaining a safe distance from the preceding vehicle using adaptive cruise control (ACC).

[0011] In order to solve the above-mentioned problems, an embodiment of the present invention aims to provide a driving control device and a driving control method that can detect the type of vehicle of a preceding vehicle and appropriately perform following driving of the subject vehicle in accordance with the acceleration responsiveness of each type of preceding vehicle. [Means for solving the problem]

[0012] A first aspect of the present invention relates to a cruise control device that causes a host vehicle to follow a preceding vehicle while maintaining a vehicle-to-vehicle distance in accordance with the acceleration of the preceding vehicle. The cruise control device includes a preceding vehicle type determination unit that determines whether the preceding vehicle is a first vehicle type or a second vehicle type using an on-board sensor, and an acceleration control unit that switches between a first control for the acceleration of the host vehicle when the preceding vehicle is the first vehicle type and a second control for the acceleration of the host vehicle when the preceding vehicle is the second vehicle type.

[0013] A second aspect of the present invention relates to a cruise control method for following a preceding vehicle while maintaining a vehicle-to-vehicle distance in accordance with the acceleration of the preceding vehicle. The cruise control method uses an on-vehicle sensor to determine whether the preceding vehicle is a first vehicle type or a second vehicle type, determines whether the preceding vehicle is the first vehicle type and traveling at a first acceleration, or whether the preceding vehicle is the second vehicle type and traveling at a second acceleration higher than the first acceleration, and switches between a first control for the acceleration of the preceding vehicle when the preceding vehicle is the first vehicle type and traveling at the first acceleration, and a second control for the acceleration of the preceding vehicle when the preceding vehicle is the second vehicle type and traveling at the second acceleration. [Effects of the Invention]

[0014] According to the embodiment of the present invention, the type of the preceding vehicle can be detected, and the host vehicle can appropriately follow the preceding vehicle in accordance with the acceleration response of each type of the preceding vehicle. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a block diagram showing a configuration of a cruise control system including a cruise control device according to an embodiment of the present invention. [Figure 2] 3 is a flowchart illustrating a cruise control method according to an embodiment of the present invention. [Figure 3] 10A is a graph showing the transition of the acceleration limit for a normal vehicle and an EV vehicle at each vehicle speed, and FIG. 10B is a graph showing the transition of the jerk limit for a normal vehicle and an EV vehicle at each vehicle speed. [Figure 4] (A) A graph showing the change in acceleration over time for a normal vehicle and an electric vehicle when accelerating to a specified vehicle speed, and (B) a graph showing the change in acceleration change rate over time for a normal vehicle and an electric vehicle when accelerating to a specified vehicle speed. DETAILED DESCRIPTION OF THE INVENTION

[0016] A cruise control device and a cruise control method according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0017] As mentioned above, EVs have better accelerator response than engine vehicles, and tend to accelerate quickly when the driver steps on the accelerator pedal. If the vehicle ahead is an EV and the vehicle is following the ACC, the vehicle will not be able to quickly follow the acceleration of the vehicle ahead if the acceleration is based on that of an engine vehicle, which could result in a loss of comfort for passengers during acceleration.

[0018] This embodiment is characterized by improving follow-up driving performance by switching acceleration control by the ACC of the vehicle in question depending on the type of vehicle (EV or engine) of the preceding vehicle. In this embodiment, the type of the preceding vehicle is determined using on-board sensors (forward camera, millimeter-wave radar, vehicle-to-vehicle communication, etc.). If it is determined that the preceding vehicle is an EV, the start-up acceleration by the ACC of the vehicle in question is temporarily increased compared to when following an engine vehicle, improving follow-up driving performance.

[0019] Vehicles may be equipped with various sensors for Advanced Driver-Assistance Systems (ADAS) or with over-the-air (OTA) data communication as a connected function. When vehicle-to-vehicle communication cannot be established, the vehicle's own vehicle can use the front camera and millimeter-wave radar of its ADAS sensors to determine the type of vehicle ahead.

[0020] A vehicle is equipped with a front camera to capture images (video) of the vehicle ahead. The image captured by the front camera can be used to identify the model of the vehicle ahead. For example, the front camera can capture an image of the emblem (license plate, etc.) of the vehicle ahead to determine the model of the vehicle ahead.

[0021] Low-power millimeter-wave radar in the tens of gigahertz band has been put into practical use to avoid collisions with obstacles ahead of the vehicle and to measure the distance between vehicles. Millimeter-wave radar transmits millimeter waves (radio waves with wavelengths of approximately 1 mm to 1 cm) from a transmitting (TX) antenna, and receives the radio waves reflected back from the target object at a receiving (RX) antenna. When millimeter-wave radar is installed on a vehicle, it is possible to determine the type of vehicle ahead based on the acceleration and deceleration characteristics of the vehicle ahead and the tendency of the millimeter waves to be reflected.

[0022] For ease of explanation, the initial setting (default) for the vehicle type of the preceding vehicle is assumed to be an engine vehicle, and the vehicle type of the preceding vehicle is determined by determining whether or not the preceding vehicle is an EV vehicle.

[0023] 1 is a block diagram showing the configuration of a cruise control system 100 including a cruise control device according to an embodiment of the present invention. The cruise control system 100 includes an input unit 200, a determination unit 300, and an output unit 400. An ADAS sensor can be used as the input unit 200. Therefore, the cruise control device according to this embodiment may be equipped with the functions of the output unit 400 in addition to the functions of the determination unit 300.

[0024] The input unit 200 is equipped with a front camera 201, a millimeter wave radar 202, and a vehicle-to-vehicle communication unit 203. The front camera 201 captures images of the area ahead of the vehicle, and obtains images of the leading vehicle and its surroundings to generate image information.

[0025] The millimeter-wave radar 202 is used to measure the distance to a preceding vehicle and to determine the type of the preceding vehicle (whether it is an EV or not) by transmitting and receiving millimeter waves. The millimeter-wave radar 202 sends out measurement information such as the distance between vehicles based on the time of transmission of millimeter-wave radio waves and the time of reception of the reflected waves from the preceding vehicle.

[0026] The inter-vehicle communication unit 203 acquires information about surrounding vehicles (such as position, speed, and vehicle control information) through wireless communication between the vehicle ahead and the vehicle itself. The inter-vehicle communication can be linked to an Intelligent Transport System (ITS). Positioning is also performed using the Global Navigation Satellite System (GNSS) to accurately and frequently update the vehicle's position. The inter-vehicle communication unit 203 transmits vehicle control information about the vehicle ahead.

[0027] The determination unit 300 includes an ACC mode determination unit 301, a preceding vehicle type determination unit 302, and an ACC acceleration determination unit 303. The ACC mode determination unit 301 determines whether the driver has operated an ACC switch (not shown) provided at the driver's seat of the host vehicle. When the driver operates the ACC switch, the host vehicle enters ACC mode and follows the preceding vehicle in conjunction with the front camera 201. In ACC mode, an on-board computer (such as an ECU) automatically operates the accelerator and brakes to maintain a constant inter-vehicle distance from the preceding vehicle based on various information obtained by the input unit 200 (image information of the preceding vehicle, measurement information related to the preceding vehicle, vehicle control information of the preceding vehicle, etc.). When the driver selects ACC mode, the ACC mode determination unit 301 generates an ACC determination signal and sends it to the ACC acceleration determination unit 303.

[0028] The preceding vehicle type determination unit 302 acquires image information of the preceding vehicle from the forward camera 201. If the image information includes the vehicle type of the preceding vehicle, it can determine whether the preceding vehicle is an internal combustion vehicle (first vehicle type) or an EV (second vehicle type) based on the image information. The preceding vehicle type determination unit 302 acquires measurement information related to the preceding vehicle from the millimeter-wave radar 202. The measurement information includes inter-vehicle distance information indicating the inter-vehicle distance from the preceding vehicle. The preceding vehicle type determination unit 302 can also determine the vehicle type (EV or not) of the preceding vehicle based on the acceleration / deceleration characteristics of the preceding vehicle and the millimeter-wave reflection tendency based on the measurement information from the millimeter-wave radar 202. The preceding vehicle type determination unit 302 acquires vehicle control information of the preceding vehicle from the vehicle-to-vehicle communication unit 203. If the vehicle control information includes the vehicle type of the preceding vehicle (identification information as to whether it is an EV or not), the preceding vehicle type determination unit 302 can determine the vehicle type (EV or not) of the preceding vehicle based on the vehicle control information from the vehicle-to-vehicle communication unit 203. The preceding vehicle type determination unit 302 generates a preceding vehicle type determination signal indicating the type of the preceding vehicle, and sends it to the ACC acceleration determination unit 303 .

[0029] ACC acceleration determination unit 303 receives an ACC mode signal from ACC mode determination unit 301 and a preceding vehicle type determination signal from preceding vehicle type determination unit 302. When ACC mode is selected by the ACC determination signal, ACC acceleration determination unit 303 determines whether the preceding vehicle is an engine vehicle (first vehicle type) or an EV vehicle (second vehicle type) based on the preceding vehicle type determination signal. For example, ACC acceleration determination unit 303 determines whether the preceding vehicle being followed by the host vehicle is traveling at a first acceleration (acceleration performance estimated from statistical values of acceleration feature amounts of engine vehicles) or a second acceleration (acceleration performance estimated from statistical values of acceleration feature amounts of EV vehicles). ACC acceleration determination unit 303 outputs an ACC acceleration determination signal indicating that the acceleration of the preceding vehicle is the first acceleration or the second acceleration.

[0030] If the preceding vehicle is an engine vehicle and the host vehicle is also an engine vehicle, there is no need to perform ACC acceleration control due to the acceleration response of the preceding vehicle, so the host vehicle's ACC operates according to the initial settings.If the preceding vehicle is an engine vehicle and the host vehicle is an EV, the acceleration response of the two vehicles will differ, but the host vehicle's ACC will operate according to the initial settings because it is possible to demonstrate good tracking ability in relation to the preceding vehicle.

[0031] When the preceding vehicle is an EV and the host vehicle is also an EV, it can be assumed that the acceleration response of both vehicles is equivalent. ACC acceleration can be tuned according to regional differences (urban, suburban, plains, mountainous, etc.), and can also be set specifically for EV vehicles. In this case, the ACC acceleration determination unit 303 determines that the preceding vehicle is an EV, but there is little need to adjust the ACC acceleration control.

[0032] When the preceding vehicle is an EV and the host vehicle is an engine vehicle, there is a difference in acceleration response between the two vehicles. Therefore, if the EV vehicle accelerates under ACC acceleration control when the preceding vehicle is an engine vehicle, it becomes difficult to maintain a constant inter-vehicle distance. For this reason, the host vehicle performs ACC acceleration control specialized for the preceding EV vehicle. ACC acceleration determination unit 303 generates an ACC acceleration determination signal indicating the ACC acceleration according to the vehicle type of the preceding vehicle and sends it to output unit 400. The ACC acceleration determination signal is an instruction to switch the ACC acceleration when the preceding vehicle is an EV and the host vehicle is an engine vehicle.

[0033] The output unit 400 includes an ACC acceleration control unit 401 and a display unit 402. The ACC acceleration control unit 401 receives an ACC acceleration determination signal from the ACC acceleration determination unit 303. In response to the ACC acceleration determination signal, the ACC acceleration control unit 401 selects and executes either a first control (ACC1) when the preceding vehicle is an engine vehicle and does not require switching of the ACC acceleration, or a second control (ACC2) when the preceding vehicle is an EV vehicle and requires switching of the ACC acceleration. In the first control of ACC acceleration, similar to the initial ACC control, the host vehicle follows the preceding vehicle while maintaining a certain inter-vehicle distance in accordance with the acceleration of the preceding vehicle. Note that in ACC control, if the host vehicle's acceleration is suddenly changed in accordance with the acceleration of the preceding vehicle, passenger comfort may be impaired. Therefore, a certain restriction (limiter) is imposed on the engine output characteristics to moderately soften the acceleration rise.

[0034] In the second control of ACC acceleration, the ACC acceleration of the host vehicle (engine vehicle) is made to rise sharply to follow the acceleration response of the preceding vehicle (EV vehicle). For example, the rate of change of engine output is increased and the time constant indicating the rate of change over time is set to a short value. The acceleration limit (limit value of acceleration) and jerk limit (limit value of jerk rate) for engine vehicles (or conventional vehicles) and EV vehicles will be described later.

[0035] As described above, ACC acceleration control unit 401 switches and executes the ACC acceleration between the first control (ACC1) and the second control (ACC2) in response to the ACC acceleration determination signal from ACC acceleration determination unit 303. As a result, when the host vehicle is an engine vehicle and the preceding vehicle is an EV vehicle, the host vehicle's acceleration can be appropriately controlled to follow the high acceleration responsiveness of the preceding vehicle, and the host vehicle can follow the preceding vehicle while maintaining a constant inter-vehicle distance even under ACC control.

[0036] The display unit 402 receives the ACC acceleration determination signal from the ACC acceleration determination unit 303 and displays on instruments (meters, etc.) installed on the driver's seat side that the host vehicle is adjusting the ACC acceleration to follow the preceding vehicle. For example, when the ACC acceleration control unit 401 switches the ACC acceleration from the first control (ACC1) to the second control (ACC2), the display unit 402 notifies the driver by an alert, a display, etc. that the ACC acceleration is rapidly increasing to follow the preceding vehicle.

[0037] The cruise control system 100 shown in Fig. 1 includes a cruise control device according to this embodiment. The input unit 100 is provided in the host vehicle as an on-board sensor, and the host vehicle is also provided with an ACC mode determination unit 301 (such as an ACC switch). The host vehicle is also provided with a display unit 402 (such as an on-board monitor or gauges). Therefore, the cruise control device may be configured with a preceding vehicle type determination unit 302, an ACC acceleration determination unit 303, and an ACC acceleration control unit 401.

[0038] Next, a cruise control method (ACC acceleration determination process) according to an embodiment of the present invention will be described with reference to the flowchart in Fig. 2. The flowchart in Fig. 2 is composed of steps S10 to S50. The ACC acceleration determination process is implemented in the cruise control device and is performed, for example, by an on-board computer (such as a CPU) executing a program stored in memory. In Fig. 1, the functions of the determination unit 300 (ACC mode determination unit 301, preceding vehicle type determination unit 302, and ACC acceleration determination unit 303) and the ACC acceleration control unit 401 of the output unit 400 correspond to the ACC acceleration determination process.

[0039] First, the cruise control device determines whether the driver of the host vehicle has operated the ACC switch to select ACC mode and the host vehicle is traveling in ACC mode (step S10). In FIG. 1, ACC mode determination unit 301 determines whether the driver of the host vehicle has selected ACC mode. Then, the cruise control device determines whether the host vehicle is traveling by following a preceding vehicle using ACC control (step S20). In FIG. 1, preceding vehicle type determination unit 302 identifies the type of preceding vehicle based on various information from input unit 200, and ACC acceleration determination unit 303 performs acceleration control using ACC control of the host vehicle to determine whether the host vehicle is traveling by following a preceding vehicle (EV vehicle).

[0040] In addition to the host vehicle, there are multiple vehicles (such as a preceding vehicle and a following vehicle) traveling on the road, and this embodiment focuses on the relationship between the host vehicle and the preceding vehicle. The preceding vehicles include not only the preceding vehicle traveling immediately before the host vehicle, but also a vehicle two vehicles ahead of the preceding vehicle traveling ahead of the preceding vehicle. Specifically, this embodiment assumes a situation in which a preceding vehicle immediately before the host vehicle is photographed by the front camera 201 and detected by the millimeter-wave radar 202. In this case, the preceding vehicle type determination unit 302 inputs image information of the preceding vehicle from the front camera 201 and inputs measurement information of the preceding vehicle (such as inter-vehicle distance information) from the millimeter-wave radar 202. Furthermore, if the preceding vehicle is able to communicate with the vehicle-to-vehicle communication unit 203 of the host vehicle, the preceding vehicle type determination unit 302 also inputs vehicle control information of the preceding vehicle (identification information as to whether it is an EV vehicle or not).

[0041] Next, the preceding vehicle type determination unit 302 determines whether the preceding vehicle to be followed is an EV (step S30). In Fig. 1, the preceding vehicle type determination unit 302 determines whether the preceding vehicle is an EV based on the image information from the front camera 201, the measurement information from the millimeter-wave radar 202, and the vehicle control information from the vehicle-to-vehicle communication unit 203.

[0042] This embodiment is characterized by switching the ACC acceleration between first control (ACC1) and second control (ACC2) depending on the determination result of step S30. If it is determined in step S30 that the preceding vehicle to be followed by the host vehicle is not an EV vehicle, the flow proceeds to step S40, where the cruise control device instructs the onboard computer (engine ECU, brake ECU, etc.) to execute ACC acceleration control (ACC1). In the first ACC acceleration control (ACC1), acceleration and deceleration are controlled so that the host vehicle follows the preceding vehicle without changing the ACC function (a function that automatically adjusts acceleration and deceleration while maintaining a distance from the preceding vehicle) equipped in the host vehicle. In this case, acceleration and deceleration control according to the acceleration responsiveness of the preceding vehicle's model is not performed.

[0043] If step S30 determines that the preceding vehicle being followed by the host vehicle is an EV, the flow proceeds to step S50, where the cruise control device instructs the onboard computer to execute ACC acceleration control (ACC2). The second ACC acceleration control (ACC2) modifies the ACC function installed in the host vehicle to increase the ACC start-up acceleration in accordance with the acceleration response of the EV vehicle, thereby improving the ability to follow the preceding vehicle. The increase in the ACC start-up acceleration is determined from statistical values of the acceleration response of various EV vehicles.

[0044] Next, the differences in acceleration and jerk (jerk rate) between a normal vehicle (such as an engine vehicle) and an EV vehicle will be explained with reference to Figures 3(A) and 3(B) and Figures 4(A) and 4(B). Generally, a vehicle has an acceleration limit and a jerk limit set for each vehicle speed.

[0045] For example, as shown in Figure 3(A), the acceleration limit (m / s 2 ) is set. Figure 3(A) shows the transition of the acceleration limit EVA of an EV vehicle and the acceleration limit SVA of a normal vehicle (such as an engine vehicle other than an EV vehicle) when the vehicle speed is changed from 0 km / h to 200 km / h. For example, when the vehicle speed of a normal vehicle is changed from 0 km / h to 120 km / h, the acceleration limit SVA is set to 1.15 m / s 2The acceleration limit SVA is maintained at 2.5 m / s, but then decreases as the vehicle speed increases. On the other hand, when the EV vehicle speed is between 0 km / h and 80 km / h, the acceleration limit EVA is 2.5 m / s. 2 to 1.5 m / s 2 At speeds of 120 km / h or more, the acceleration limit EVA is reduced in accordance with the increase in vehicle speed. In particular, at speeds below 80 km / h, the legal speed limit in Japan, there are differences in the acceleration limits SVA and EVA between standard vehicles and EVs, resulting in differences in the acceleration response of the two.

[0046] Figure 3(B) shows the time-dependent changes in the accelerations SVA25 and EVA25 of a normal vehicle and an EV vehicle when the vehicle speed is 25 km / h (the transition of the initial acceleration from the first 0 seconds to 5 seconds). In other words, the acceleration SVA25 of a normal vehicle at a vehicle speed of 25 km / h is 0 m / s 2 to 1.15 m / s 2 The acceleration of the EV vehicle EVA25 is 0 m / s 2 to 2 m / s 2 As such, even at the same vehicle speed, there is a difference in the change in acceleration between a regular car and an EV, with EVs having better acceleration response than regular cars.

[0047] Next, a comparison of the jerk (jerk) between a normal vehicle and an EV vehicle will be described with reference to FIGS. 4(A) and 4(B).

[0048] As shown in Figure 4(A), the jerk limit (m / s 3 ) is set. Figure 4(A) shows the transition of the jerk limit EVR for EV vehicles and the jerk limit SVR for standard vehicles (engine vehicles other than EV vehicles) when the vehicle speed is changed from 0 km / h to 200 km / h. For example, when the vehicle speed of a standard vehicle is changed from 0 km / h to 120 km / h, the jerk limit SVR is set to 0.26 m / s 3 The jerk limit SVR is maintained at 0.56 m / s, but then decreases as the vehicle speed increases. On the other hand, when the EV vehicle speed is between 0 km / h and 80 km / h, the jerk limit EVR is 0.56 m / s3 to 0.34 m / s 3 At speeds above 120 km / h, the EVR jerk limiter is lowered in accordance with the increase in vehicle speed. In particular, at speeds below 80 km / h, the legal speed limit in Japan, there are differences in the SVR and EVR jerk limits between standard vehicles and EVs, resulting in differences in the acceleration response of the two.

[0049] Figure 4(B) shows the time-dependent changes in the jerk SVR25 and EVR25 of a standard vehicle and an EV vehicle when the vehicle speed is 25 km / h (the transition of the initial jerk from the first 0 seconds to 5 seconds). That is, the jerk SVR25 of a standard vehicle at a vehicle speed of 25 km / h is 0.24 m / s in the first 0.5 seconds. 3 After that, it remains constant with some fluctuations, and between 4 and 5 seconds, it is 0.1 m / s 3 The jerk EVR25 of an EV vehicle at a vehicle speed of 25 km / h also changes in the same way as the jerk SVR25 of a standard vehicle. In other words, the jerk EVR25 of an EV vehicle is 0.45 m / s 3 It then remains constant and drops to 0.1 m / s between 4 and 5 seconds. 3 In this way, even at the same vehicle speed, there is a difference in the jerk between a regular vehicle and an EV, with EVs having better acceleration response than regular vehicles.

[0050] 1, in this embodiment, three types of input devices (or on-board sensors) 201 to 203 are shown in the input unit 200, and the accuracy of determining the type of preceding vehicle depends on the angle of view and image quality of the front camera 201, the transmission and reception accuracy of the millimeter-wave radar 202, and the communication status of the vehicle-to-vehicle communication unit 203. Whether the preceding vehicle is an EV can be determined using the front camera 201 and / or the vehicle-to-vehicle communication unit 203. Meanwhile, the millimeter-wave radar 202 is used to detect the distance between the vehicle itself and the preceding vehicle.

[0051] The millimeter-wave radar 202 can detect not only the preceding vehicle traveling immediately in front of the host vehicle, but also the vehicle two vehicles ahead of the preceding vehicle. When the vehicle two vehicles ahead is present, multiple preceding vehicles are traveling in a line ahead of the host vehicle, and if the preceding vehicle is an EV, the presence of the vehicle two vehicles ahead also limits the acceleration change. For this reason, there is no need to significantly increase the rise in the ACC acceleration of the host vehicle to match the acceleration responsiveness of the preceding vehicle. In other words, if the rise in the ACC acceleration of the host vehicle is increased and the host vehicle repeatedly accelerates and decelerates despite the presence of the vehicle two vehicles ahead of the preceding vehicle, passenger comfort may be impaired.

[0052] On the other hand, if there is no vehicle ahead of the preceding vehicle, if the preceding vehicle is an EV, the acceleration may be significantly increased, and it is possible to further increase the ACC acceleration of the host vehicle to improve tracking performance. For example, if there is no vehicle ahead of the preceding vehicle within a predetermined distance ahead of the preceding vehicle, the rise in the ACC acceleration of the host vehicle can be temporarily increased to improve tracking response while maintaining passenger comfort. The predetermined distance can be, for example, the distance when multiple vehicles are lined up in a tandem (more than several tens of meters). This is because setting the predetermined distance too short would result in sudden increases and decreases in the ACC acceleration of the host vehicle, which could impair passenger comfort.

[0053] In other words, when the vehicle ahead of the vehicle is not within a predetermined distance, the preceding vehicle, the electric vehicle, tends to increase its acceleration. For this reason, the switching of ACC control in this embodiment (the temporary increase in the rise of ACC acceleration) may be limited to a situation where the vehicle ahead of the vehicle is not present. For example, step S30 in FIG. 2 may be specified as to whether the vehicle ahead of the vehicle is an electric vehicle and there is no vehicle ahead of the vehicle within a predetermined distance from the preceding vehicle. In this case, when a vehicle ahead of the vehicle is present, the flow may proceed to step S40, where the first control of ACC acceleration is executed. On the other hand, when a vehicle ahead of the vehicle is not present, the flow may proceed to step S50, where the second control of ACC acceleration is executed.

[0054] As described above, by limiting the switching of the ACC acceleration of the vehicle to situations where there is no vehicle ahead, it is possible to prevent the ACC control of the vehicle from switching frequently, which would impair the driver's predictability (predictability of changes in acceleration control that are suited to the vehicle ahead) and reduce passenger comfort.

[0055] This embodiment is characterized by improving acceleration response by increasing the rise in ACC acceleration of the vehicle when it is determined that the preceding vehicle is an EV. However, it is also possible to adjust the ACC acceleration by identifying the vehicle model of the preceding vehicle in detail. For example, the acceleration and deceleration rates of EVs may be adjusted by the automobile manufacturer, and the rate of acceleration and deceleration may vary depending on the flatness and inclination of the road. Furthermore, it is expected that the rate of acceleration and deceleration of EVs will vary depending on changes in road conditions caused by weather. For this reason, it is possible to store driving data for multiple EVs in a table format based on the magnitude of the rate of change in the rise in acceleration of EVs, using vehicle control information from each manufacturer and statistical values of acceleration and deceleration according to road conditions, and adjust the rise in ACC acceleration individually depending on the identified EV driving data.

[0056] Next, the effects of this embodiment will be described. Compared to simply controlling the acceleration of the host vehicle in accordance with the acceleration of the preceding vehicle, this embodiment individually adjusts the acceleration and tracking ability for each type of preceding vehicle (engine vehicle or EV vehicle), enabling a comfortable ACC tracking driving that is natural to the driver.

[0057] ACC control achieves tracking control by applying feedback based on the acceleration and distance of the preceding vehicle. This tracking control takes time to obtain accurate acceleration information from the preceding vehicle, and time is also required for the acceleration information to be reflected in the tracking control. In addition, since it is unknown how the acceleration of the preceding vehicle will change, parameters can be adjusted in advance to achieve comfortable tracking control by taking the median of statistical values of acceleration based on a general vehicle.

[0058] However, even though acceleration performance is clearly different between engine vehicles and EV vehicles, it is not realistic to perform parameter adjustment using the median value of the acceleration performance of engine vehicles and EV vehicles. When the preceding vehicle is an EV, the vehicle's ability to follow the preceding vehicle tends to be low, and when the preceding vehicle is an engine vehicle, the vehicle catches up too quickly, which can cause the driver to feel uncomfortable.

[0059] In particular, when the inter-vehicle distance increases in response to a sudden acceleration of the preceding vehicle due to differences in acceleration performance between the preceding vehicle and the subject vehicle, the driver of the subject vehicle is likely to become dissatisfied with the acceleration performance of the subject vehicle as the inter-vehicle distance from the preceding vehicle gradually increases. In this embodiment, when it is detected that the preceding vehicle is an EV, the acceleration of the subject vehicle under ACC control is appropriately set and adjusted to match that of an EV. This embodiment can eliminate the driver's dissatisfaction with the acceleration of the subject vehicle under ACC control and improve passenger comfort.

[0060] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0061] 100 Driving Control System 200 Input section 201 Front camera 202 Millimeter wave radar 203 Inter-vehicle communication unit 300 Judgment section 301 ACC mode determination unit 302 Leading vehicle type determination unit 303 ACC acceleration determination section 400 Output Section 401 ACC acceleration control unit 402 Display section

Claims

1. A driving control device that makes a vehicle follow a preceding vehicle while maintaining a vehicle-to-vehicle distance in accordance with the acceleration of the preceding vehicle, a preceding vehicle type determination unit that determines whether the preceding vehicle is a first vehicle type or a second vehicle type using an on-board sensor; an acceleration control unit that switches between a first control for acceleration of the host vehicle when the preceding vehicle is the first vehicle type and a second control for acceleration of the host vehicle when the preceding vehicle is the second vehicle type; A driving control device comprising:

2. 2. The driving control device according to claim 1, further comprising an acceleration determination unit that determines whether the preceding vehicle is traveling at a first acceleration when the preceding vehicle is the first vehicle type, or whether the preceding vehicle is traveling at a second acceleration higher than the first acceleration when the preceding vehicle is the second vehicle type, and the acceleration control unit switches between the first control of the acceleration of the host vehicle when the preceding vehicle is the first vehicle type and traveling at the first acceleration, and the second control of the acceleration of the host vehicle when the preceding vehicle is the second vehicle type and traveling at the second acceleration.

3. 2. The cruise control device according to claim 1, wherein the second control temporarily increases the rise in acceleration of the host vehicle following the preceding vehicle compared to the first control.

4. 2. The driving control device according to claim 1, characterized in that even if the preceding vehicle type determination unit determines that the preceding vehicle is the second vehicle type, if the on-board sensor detects that a vehicle ahead of the preceding vehicle is present within a predetermined distance ahead of the preceding vehicle, the acceleration control unit maintains the first control.

5. 3. The driving control device according to claim 2, characterized in that when the on-board sensor no longer detects the presence of the preceding vehicle within the predetermined distance ahead of the preceding vehicle, and when the acceleration determination unit determines that the preceding vehicle is traveling at the second acceleration, the acceleration control unit switches the acceleration of the host vehicle to the second control.

6. A driving control method for making a vehicle follow a preceding vehicle while maintaining a vehicle-to-vehicle distance in accordance with the acceleration of the preceding vehicle, comprising: Using an on-board sensor, determine whether the preceding vehicle is a first type or a second type; determining whether the preceding vehicle is traveling at a first acceleration when the preceding vehicle is the first vehicle type, or whether the preceding vehicle is traveling at a second acceleration higher than the first acceleration when the preceding vehicle is the second vehicle type; A driving control method characterized by switching between a first control for the acceleration of the host vehicle when the preceding vehicle is the first vehicle type and is traveling at the first acceleration, and a second control for the acceleration of the host vehicle when the preceding vehicle is the second vehicle type and is traveling at the second acceleration.

7. 7. The cruise control method according to claim 6, wherein the second control temporarily increases the rise in acceleration of the host vehicle following the preceding vehicle, compared to the first control.

8. The driving control method described in claim 7, characterized in that even if the preceding vehicle is determined to be the second vehicle type, if the on-board sensor detects that a vehicle ahead of the preceding vehicle is present within a predetermined distance ahead of the preceding vehicle, the first control is maintained with respect to the acceleration of the vehicle.

9. 9. The driving control method according to claim 8, characterized in that when the on-board sensor no longer detects the presence of the preceding vehicle within the predetermined distance ahead of the preceding vehicle, and it is determined that the preceding vehicle is traveling at the second acceleration, the acceleration of the subject vehicle is switched to the second control.

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