Adaptive cruise control system

Abstract

This invention provides a follow-me cruise control system that can achieve acceleration that meets the standard noise level and standard vibration level. [Solution] The adaptive cruise control system 10 is a system that drives its own vehicle 5 in accordance with a preceding vehicle 6, and calculates a first acceleration required to follow the preceding vehicle 6, calculates a second acceleration that can be achieved in the lowest gear among the gears that can satisfy the standard noise level and standard vibration level, and if the first acceleration is greater than the second acceleration, sets the target acceleration to the second acceleration.

Description

Technical Field

[0001] The present disclosure relates to a follow-up cruise control system that causes a host vehicle to travel following a preceding vehicle.

Background Art

[0002] A cruise control system is a system that automatically maintains a speed set by a driver. A follow-up cruise control system, also called an adaptive cruise control, a constant speed driving control system, a vehicle-to-vehicle distance control system, etc., is a system that automatically adjusts the speed in accordance with a preceding vehicle running ahead of the host vehicle. That is, the follow-up cruise control system is obtained by additionally implementing an advanced driving assistance system on the cruise control system.

[0003] For example, Patent Document 1 discloses a follow-up cruise control system that filters the difference between the acceleration engine speed required to follow a preceding vehicle and the steady engine speed required to travel at a constant vehicle speed with a time constant of a first-order lag and adds the result to the steady engine speed to obtain a target engine speed.

[0004] According to the follow-up cruise control system of Patent Document 1, a system can be realized in which the engine speed does not become too high and the reference noise level and the reference vibration level are satisfied.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the adaptive cruise control system described in Patent Document 1 is based on the premise of a vehicle driven by a continuously variable transmission and cannot be applied to a vehicle driven by a stepped transmission. Therefore, there is a need for an adaptive cruise control system that can achieve acceleration that satisfies the standard noise level and standard vibration level regardless of the type of transmission.

[0007] Therefore, the present invention aims to provide a follow-up cruise control system that can achieve acceleration that satisfies standard noise levels and standard vibration levels, regardless of the type of transmission. [Means for solving the problem]

[0008] The adaptive cruise control system according to the present invention is a cruise control system that drives its own vehicle in accordance with a preceding vehicle, and is characterized by calculating a first acceleration necessary to follow the preceding vehicle, calculating a second acceleration achievable in the lowest gear among the gears that can satisfy the standard noise level and standard vibration level, and setting the target acceleration to the second acceleration if the first acceleration is greater than the second acceleration. [Effects of the Invention]

[0009] According to the adaptive cruise control system of the present invention, acceleration that always satisfies the standard noise level and standard vibration level can be achieved regardless of the type of transmission, thereby reducing the feeling of insufficient acceleration and discomfort caused by fluctuations in engine speed to the driver. [Brief explanation of the drawing]

[0010] [Figure 1] This is a diagram illustrating an example of an adaptive cruise control system. [Figure 2] This block diagram shows the configuration of a follow-me type cruise control system, which is an example of an embodiment. [Figure 3] This is a flowchart illustrating the flow of a follow-me type cruise control, which is one example of an embodiment. [Modes for carrying out the invention]

[0011] An example of an embodiment of the present invention will be described in detail below. In the following description, specific shapes, materials, directions, numerical values, etc., are examples to facilitate understanding of the present invention and can be appropriately modified according to the application, purpose, specifications, etc.

[0012] [Adaptive Cruise Control System] An example of an embodiment, a follow-type cruise control system 10, will be described using Figures 1 and 2.

[0013] As shown in Figure 1, the adaptive cruise control system 10 (hereinafter referred to as the ACC (Adaptive Cruise Control) system 10) is a system that automatically adjusts the speed of the vehicle 5 in accordance with the preceding vehicle 6 traveling in front of the vehicle 5. The vehicle 5 detects the situation of the preceding vehicle 6 traveling in front using radar or a camera, adjusts its speed according to the situation of the preceding vehicle 6, and maintains a safe distance from the preceding vehicle 12. The ACC system 10 allows for safe driving while reducing the burden on the driver's driving operations.

[0014] The vehicle in this embodiment is, for example, an engine-powered vehicle driven by a stepped transmission. Although the vehicle in this embodiment is an engine-powered electric vehicle, the present invention is not limited to this. The vehicle in this invention may be a hybrid electric vehicle (HEV) or a plug-in hybrid electric vehicle (PHEV).

[0015] According to the ACC system 10 of this embodiment, as will be described in detail later, it is possible to achieve acceleration that satisfies the standard noise level and standard vibration level regardless of the type of transmission. This reduces the feeling of insufficient acceleration and discomfort caused by fluctuations in engine speed that the driver may experience.

[0016] As shown in FIG. 2, the ACC system 30 includes an ECU 50 (Electronic Control Unit) and in-vehicle devices.

[0017] The ECU 50 includes an ACC-ECU 51 and a drive ECU 52. The ACC-ECU 51 and the drive ECU 52 are interconnected by a bus 55 to exchange information with each other. Note that the ACC system 10 may include other ECUs.

[0018] Each ECU includes a processor represented by a CPU, a storage device such as a semiconductor memory, an interface with an external device, etc. The storage device stores programs executed by the processor or data used by the processor for processing. Each ECU may include a plurality of processors, storage devices, interfaces, etc.

[0019] The ACC-ECU 51 has a function of performing ACC control. The ACC control includes control for automatically maintaining the speed set by a normal driver and control for automatically adjusting the speed in accordance with a preceding vehicle 6 running in front of the host vehicle 5. An external sensor 20 and an ACC switch 31 that respectively constitute in-vehicle devices are connected to the ACC-ECU 51.

[0020] The external sensor 20 is a group of sensors used for detecting the surrounding environment of the vehicle. The external sensor 20 includes, for example, a camera 21 that images the surroundings of the vehicle. The camera 21 includes a front vehicle camera that images the front of the vehicle.

[0021] The external sensor 20 may include a millimeter-wave radar that transmits a probing wave and receives a reflected wave. The millimeter-wave radar may detect an object such as a preceding vehicle 6 stopped in front of the host vehicle 5 using radio waves (e.g., millimeter waves). The millimeter-wave radar may also detect an object by transmitting radio waves around the host vehicle 5 and receiving the radio waves reflected by the object.

[0022] The external sensor 20 may include a lidar that scans the front of the host vehicle 5. The lidar uses light to detect an object outside the host vehicle 5. The lidar may transmit light around the host vehicle 5 and measure the distance to the reflection point by receiving the light reflected by the object, thereby detecting the object.

[0023] The ACC switch 31 is, for example, arranged around the driver's seat and is a switch for switching on and off to select whether to execute the ACC system 10.

[0024] The ACC-ECU 51 automatically adjusts the speed in accordance with the preceding vehicle 6 running in front of the host vehicle 5. More specifically, when the preceding vehicle 6 is confirmed based on the information in front of the host vehicle 5 acquired by the camera 21, the ACC-ECU 51 acquires information about the preceding vehicle 6 such as the relative vehicle speed and the inter-vehicle distance from the preceding vehicle 6, sets a target vehicle speed for the host vehicle 5 to follow the preceding vehicle 6, and calculates a first acceleration necessary to achieve the target vehicle speed.

[0025] The ACC-ECU 51 may set the constant vehicle speed (set vehicle speed) set by the driver as the target vehicle speed when the preceding vehicle 6 cannot be confirmed based on the information in front of the host vehicle 5 acquired by the camera 21.

[0026] The drive ECU 52 controls the output of the engine according to the required torque calculated from the signal of the accelerator sensor or the like. The drive ECU 52 also controls the output of the engine by setting a target acceleration. Further, the drive ECU 52 calculates a second acceleration that satisfies the NV (Noise Vibration) conditions, which will be described later in detail. An external sensor 20 that constitutes an in-vehicle device is connected to the drive ECU 52. The external sensor 20 includes a vehicle speed sensor 22 that detects the speed or acceleration of the vehicle.

[0027] As described above, the drive ECU 52 has a CPU 61 and a memory 62. The memory 62 stores a processing program 63, data for the processing program 64, and an NV database 65 that shows the correlation between vehicle speed and the engine speed range that satisfies the NV conditions. Note that other programs and databases may also be stored in the memory 62.

[0028] The NV database 65 may be, for example, a map showing the correlation between vehicle speed and the range of engine speeds that satisfy the NV conditions. The NV conditions are the conditions for a reference noise level and a reference vibration level, for example, the range of noise levels and vibration levels that do not cause discomfort to the driver.

[0029] The processing program 63, as will be described in detail later, calculates the range of engine speeds that satisfy the NV condition, determines the lowest gear among the gear stages that satisfy the NV condition, calculates the second acceleration as the actual acceleration that satisfies the NV condition, and if the second acceleration is greater than the first acceleration, sets the target acceleration to the second acceleration.

[0030] The processing program 63 is executed by the CPU 61. The processing program data 64 temporarily stores data when the CPU 61 executes the processing program 63, as well as setting values ​​necessary for the execution of the processing program 63. The operation of the drive ECU 52 is realized when the CPU 61 executes the processing program 63.

[0031] [ACC control] The flow of ACC control will be explained using Figure 3.

[0032] ACC control is performed by the CPU 61 of the drive ECU 52, which constitutes the ACC system 10 described above, as follows:

[0033] In step S11, the CPU 61 calculates the engine speed range that satisfies the NV conditions. More specifically, the CPU 61 calculates the engine speed range that satisfies the NV conditions at the current vehicle speed based on the current vehicle speed detected by the vehicle speed sensor 22 and the NV database 65.

[0034] In step S12, the CPU 61 determines the lowest gear among the gears of the stepped transmission that satisfy the NV condition. More specifically, the CPU 61 determines the lowest gear among the gears after shifting in which the difference between the engine speed in the current gear and the engine speed in the gear after shifting is smaller than the engine speed range calculated in step S11. The engine speed in the gear after shifting may be calculated, for example, using the current vehicle speed and the gear ratio after shifting.

[0035] In step S13, the CPU 61 calculates a second acceleration as the acceleration that satisfies the NV condition. More specifically, the CPU 61 calculates the second acceleration by subtracting the current estimated resistance from the driving force in the gear determined in step S12 and dividing by the vehicle weight. At this time, the driving force may be calculated by dividing the dynamic load radius of the tire from the product of the engine torque, gear ratio, final reduction ratio, and transmission efficiency. The current estimated resistance may also be calculated by subtracting the product of the current acceleration and the vehicle weight from the current estimated driving force.

[0036] In step S13, the CPU 61 receives the first acceleration from the ACC-ECU 51 and checks whether the first acceleration is less than the second acceleration. If the answer in step S13 is YES, the process proceeds to step S14. If the answer is NO, the process proceeds to step S15.

[0037] In step S14, the CPU 61 sets the first acceleration as the target acceleration. In step S15, the CPU 61 sets the second acceleration as the target acceleration.

[0038] As explained above, the drive ECU 52, which constitutes the ACC system 10, calculates a second acceleration as the acceleration that satisfies the NV condition. If the second acceleration is greater than the first acceleration required to make the vehicle 5 follow the preceding vehicle 6, the target acceleration is set to the second acceleration. This makes it possible to achieve acceleration that satisfies the standard noise level and standard vibration level regardless of the type of transmission. As a result, the ACC function can be implemented without giving the driver a feeling of insufficient acceleration.

[0039] It should be noted that the present invention is not limited to the embodiments and their modifications described above, and various changes and improvements are possible within the scope of the claims of this application. [Explanation of symbols]

[0040] 5 Self-vehicle, 6 Preceding vehicle, 10 Adaptive Cruise Control (ACC) system, 20 External sensors, 21 Camera, 22 Vehicle speed sensor, 31 ACC switch, 50 ECU, 51 ACC-ECU, 52 Drive ECU, 55 Bus, 61 CPU, 62 Memory, 63 Processing program, 64 Data for processing program, 65 NV database

Claims

[Claim 1] A follow-type cruise control system that drives the vehicle in accordance with the vehicle in front, The first acceleration required to follow the preceding vehicle is calculated, The second acceleration achievable with the lowest gear among those gears that can satisfy the standard noise level and standard vibration conditions is calculated. If the first acceleration is greater than the second acceleration, the target acceleration is set to the second acceleration. Adaptive cruise control system.

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