Driving assistance device

Abstract

A driving assistance device capable of smoothly accelerating from a parking or a speed close to a parking. A target acceleration / deceleration output section of the driving assistance device includes a first map in which a first target acceleration corresponding to a vehicle-to-vehicle distance and a relative speed is stored, a second map in which a second target acceleration corresponding to the vehicle-to-vehicle distance and the relative speed and greater than the first target acceleration with respect to the vehicle-to-vehicle distance and the relative speed is stored, and a selection section that selects an output using the first map and / or an output using the second map according to a host vehicle speed.

Description

Technical Field

[0001] This disclosure relates to a driver assistance device that assists in driving a vehicle. Background Technology

[0002] In recent years, adaptive cruise control (hereinafter referred to as "ACC") has attracted attention as one of the technologies to assist vehicle driving (for example, see Patent Document 1). ACC is a technology that acquires the vehicle's speed, the relative speed of the vehicle in front, and the distance between the vehicle and the vehicle in front, and controls the vehicle's drive system and braking system to keep the vehicle speed and the distance between the vehicle and the vehicle in front constant.

[0003] In addition, in ACC, when there is no vehicle ahead, cruise control (hereinafter referred to as "CC") is generally used to control the speed of the vehicle to a preset speed.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent document 1: Japanese Patent Application Publication No. 7-17295. Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In ACC, the target acceleration or deceleration is calculated based on the distance to the vehicle ahead and the relative speed, and the drive system and braking system are controlled based on the target acceleration or deceleration.

[0009] However, the torque required for acceleration, such as when starting from a stop, is greater than during normal driving. That is, the torque required to achieve the same acceleration is greater when starting than during normal driving. Therefore, even if the same target acceleration is output from the ACC target acceleration / deceleration output unit, the actual acceleration at the speed when stopping or approaching a stop will be smaller than during normal driving. As a result, an undesirable situation arises where acceleration from the speed when stopping or approaching a stop is not responsive enough.

[0010] This disclosure was made with the above considerations in mind, and provides a driving assistance device that can smoothly accelerate from a parking or approaching parking speed.

[0011] Methods for solving problems

[0012] One aspect of the driving assistance device disclosed herein is a driving assistance device for assisting in driving a vehicle, the driving assistance device comprising:

[0013] The workshop distance to the testing department measures the workshop distance between the testing vehicle and the vehicle ahead.

[0014] The relative speed detection unit detects the relative speed between this vehicle and the vehicle in front; and

[0015] The target acceleration / deceleration output unit outputs the target acceleration / deceleration of the vehicle based on the inter-vehicle distance and the relative speed.

[0016] The target acceleration / deceleration output unit includes:

[0017] The first mapping stores a first target acceleration corresponding to the workshop distance and the relative velocity;

[0018] A second mapping stores a second target acceleration, which corresponds to the shop-to-shop distance and the relative velocity, and is greater than the first target acceleration in relation to the shop-to-shop distance and the relative velocity; and

[0019] The selection unit selects whether to use the output of the first mapping and / or the output of the second mapping based on the vehicle speed.

[0020] Invention Effects

[0021] According to this disclosure, it is possible to smoothly accelerate from the speed of parking or approaching parking. Attached Figure Description

[0022] Figure 1 This is an exterior view of an example of a vehicle in which the driving assistance device involved in the implementation method is applied.

[0023] Figure 2 This is a block diagram illustrating the vehicle structure of an embodiment.

[0024] Figure 3 This is a block diagram showing the structure of a driver assistance device.

[0025] Figure 4 This is a flowchart illustrating the acceleration / deceleration output processing of a driver assistance device. Detailed Implementation

[0026] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0027] (1) Vehicle structure

[0028] First, the structure of a vehicle including a driving assistance device according to one embodiment of this disclosure will be described.

[0029] Figure 1 This is an exterior view showing an example of a vehicle 1 equipped with the driving assistance device according to this embodiment. Additionally, Figure 2This is a block diagram showing the structure of vehicle 1. Furthermore, the diagrams and descriptions here focus on the parts associated with the driver assistance devices.

[0030] like Figure 1 As shown, vehicle 1 is a tractor unit (tractor) capable of connecting and towing trailer 2. Vehicle 1 has: a vehicle body 3, including a power system such as an engine and drive wheels, and a driver's seat; and trailer 2, which is connected to vehicle body 3.

[0031] like Figure 2 As shown, vehicle 1 has a drive system 10 for driving vehicle 1, a braking system 20 for decelerating vehicle 1, and a driving assistance device 30 for assisting the driver in driving vehicle 1.

[0032] The drive system 10 includes an engine 11, a clutch 12, a transmission 13, a propeller shaft 14, a differential gear 15, a drive shaft 16, wheels 17, an engine ECU 18, and a power transmission ECU 19.

[0033] The engine ECU 18 and the power transmission ECU 19 are connected to the driver assistance device 30 via an in-vehicle network such as CAN (Controller Area Network), enabling them to send and receive necessary data and control signals. The engine ECU 18 controls the output of the engine 11 according to the drive commands from the driver assistance device 30. The power transmission ECU 19 controls the engagement and disengagement of the clutch 12 and the gear shifting of the transmission 13 according to the drive commands from the driver assistance device 30.

[0034] The power from engine 11 is transmitted to transmission 13 via clutch 12. The power transmitted to transmission 13 is further transmitted to wheels 17 via drive shaft 14, differential 15, and drive shaft 16. Thus, the power from engine 11 is transmitted to wheels 17, causing vehicle 1 to move.

[0035] The braking system 20 includes a service brake 21, auxiliary brakes 22 and 23, a parking brake (not shown) and a braking ECU 24.

[0036] The common brake 21 is usually referred to as the main brake, friction brake, foot brake, or basic brake. The common brake 21 is, for example, a drum brake that obtains braking force by pressing brake pads against the inside of a drum that rotates together with the wheel 17.

[0037] The auxiliary brake 22 is a reducer (hereinafter referred to as "reducer 22") that obtains braking force by directly applying a load to the rotation of the propulsion shaft 14, such as an electromagnetic reducer. The auxiliary brake 23 is an exhaust brake (hereinafter referred to as "exhaust brake 23") that utilizes the rotational resistance of the engine to improve the engine braking effect. By providing the reducer 22 and the exhaust brake 23, the braking force can be increased and the frequency of use of the regular brake 21 can be reduced, thus suppressing the wear of brake pads and the like.

[0038] The braking ECU 24 is connected to the driver assistance device 30 via a vehicle network such as CAN, and can send and receive the necessary data and control signals. The braking ECU 24 controls the braking force of the service brake 21 (the brake hydraulic pressure of the wheel cylinders of the wheel 17) according to the braking commands from the driver assistance device 30.

[0039] The braking action of the service brake 21 is controlled by the driver assistance device 30 and the braking ECU 24. The braking action of the reducer 22 and the exhaust brake 23 is controlled by the driver assistance device 30 in an on / off manner. Since the braking force of the reducer 22 and the exhaust brake 23 is approximately fixed, the service brake 21, which allows for fine adjustment of the braking force, is suitable for accurately generating the desired braking force.

[0040] The driver assistance device 30 receives information from millimeter-wave radar and cameras. The information from the millimeter-wave radar and cameras indicates the traffic and road conditions ahead of the vehicle. In addition, the driver assistance device 30 includes an ACC operation unit 41, an accelerator operation detection unit 43, and a brake operation detection unit 44.

[0041] The driving assistance device 30 generates control signals for controlling the operation of the drive system 10 and the braking system 20. In particular, the driving assistance device 30 of this embodiment determines the target acceleration and deceleration for achieving ACC and outputs them appropriately to the engine ECU 18, the power transmission ECU 19, and the braking ECU 24.

[0042] Furthermore, although not shown in the figures, the engine ECU 18, power transmission ECU 19, braking ECU 24, and driving assistance device 30, for example, each have a CPU (Central Processing Unit), a storage medium such as ROM (Read Only Memory) storing control programs, an operating memory such as RAM (Random Access Memory), and a communication circuit. In this case, for example, the functions of each part constituting the driving assistance device 30 described later are implemented by the CPU executing the control programs. Furthermore, all or part of the engine ECU 18, power transmission ECU 19, braking ECU 24, and driving assistance device 30 may also be integrally formed.

[0043] The ACC operation unit 41 includes an ACC start / stop switch for controlling the start and stop of ACC operation. Additionally, the ACC operation unit 41 includes setting switches for various ACC settings. By operating the setting switches, the driver can set, for example, target distance to other vehicles and target vehicle speed. Furthermore, these switches can also be configured via a user interface displayed on a touch panel.

[0044] The accelerator operation detection unit 43 detects the amount of pressure applied to the accelerator pedal and outputs the detection result to the driver assistance device 30. The driver assistance device 30 sends drive commands to the engine ECU 18 and the power transmission ECU 19 based on the amount of pressure applied to the accelerator pedal.

[0045] The brake operation detection unit 44 detects the amount of pressure applied to the brake pedal used to actuate the service brake 21. Additionally, the brake operation detection unit 44 detects whether the auxiliary brake lever, which actuates the reducer 22 or the exhaust brake 23, has been operated. Furthermore, the brake operation detection unit 44 outputs the detection results related to the brake pedal and the auxiliary brake lever to the driver assistance device 30. The driver assistance device 30 sends a braking command to the braking ECU 24 based on the amount of pressure applied to the brake pedal. Furthermore, the driver assistance device 30 controls the activation / deactivation of the reducer 22 or the exhaust brake 23 based on the operation of the auxiliary brake lever.

[0046] In addition, the driving assistance device 30 outputs various driving-related information from the information output unit 50. For example, it outputs information such as whether ACC is in operation or stopped via sound or display from the information output unit 50.

[0047] (2) Structure and operation of driver assistance devices

[0048] Figure 3 This is a block diagram showing the structure of the driving assistance device 30 according to this embodiment.

[0049] The driving assistance device 30 includes a vehicle distance detection unit 101, a relative speed detection unit 102, and a target acceleration / deceleration output unit 110.

[0050] The vehicle-to-vehicle distance detection unit 101 and the relative speed detection unit 102 measure (detect) the vehicle-to-vehicle distance and relative speed between the vehicle 1 and the preceding vehicle based on information obtained from millimeter-wave radar, cameras, etc., and output the measurement results to the target acceleration / deceleration output unit 110. Alternatively, the vehicle-to-vehicle distance detection unit 101 and the relative speed detection unit 102 can also measure the vehicle-to-vehicle distance and relative speed based on information from other sensors such as lidar.

[0051] The target acceleration / deceleration output unit 110 outputs a target acceleration / deceleration to enable the vehicle to follow the preceding vehicle based on the distance between the vehicle and the preceding vehicle and their relative speed. This enables automatic following control. Furthermore, when there is no preceding vehicle, the target acceleration / deceleration output unit 110 outputs a target acceleration to maintain the vehicle's speed at a preset constant speed. This enables constant speed driving control.

[0052] Automatic following control refers to the control that, when a vehicle is traveling ahead within a specified range, activates the drive system 10 and the braking system 20 to bring the vehicle's distance to the vehicle within a specified target range and the relative speed close to zero. Constant speed control refers to the control that, when no vehicle is traveling ahead within a specified range, activates the drive system 10 and the braking system 20 to bring the vehicle's speed close to a specified target value.

[0053] The target acceleration / deceleration output unit 110 of this embodiment has a first mapping 111, a second mapping 112, a selection unit 113, and a synthesis unit 114.

[0054] The first mapping 111 stores the first target acceleration corresponding to the shop distance and relative velocity. In fact, in addition to the first target acceleration, the first mapping 111 also stores the first target deceleration. The shop distance and relative velocity are input, and the corresponding first target acceleration and deceleration are output.

[0055] The second mapping 112 stores a second target acceleration that corresponds to the shop distance and relative velocity, and is greater than the first target acceleration in terms of shop distance and relative velocity. In fact, in addition to the second target acceleration, the second mapping 112 also stores a second target deceleration. The shop distance and relative velocity are input, and the corresponding second target acceleration and deceleration are output.

[0056] Here, the first target deceleration stored in the first mapping 111 and the second target deceleration stored in the second mapping 112 can be the same or different values ​​with respect to the workshop distance and relative velocity.

[0057] The selection unit 113 selects whether to use the output of the first mapping 111 and / or the output of the second mapping 112 based on the vehicle speed.

[0058] The synthesis unit 114 synthesizes the output of the first mapping 111 and the output of the second mapping 112.

[0059] Figure 4 This is a flowchart illustrating the acceleration / deceleration output processing of the target acceleration / deceleration output unit 110.

[0060] In step S11, the selection unit 113 determines whether the vehicle speed V is above a first threshold Th1. If it is above the first threshold Th1, the process moves to step S12, where the selection unit 113 selects the first mapping 111. Thus, the target acceleration / deceleration corresponding to the inter-vehicle distance and relative speed is output from the first mapping 111.

[0061] In contrast, in step S11, if the vehicle speed V is less than the first threshold Th1, the process moves to step S13.

[0062] In step S13, the selection unit 113 determines whether the vehicle speed V is below the second threshold Th2. If it is below the second threshold Th2, the process moves to step S14, where the selection unit 113 selects the second mapping 112. Thereby, the target acceleration / deceleration corresponding to the inter-vehicle distance and relative speed is output from the second mapping 112.

[0063] Furthermore, the first threshold Th1 and the second threshold Th2 are related as Th1 > Th2.

[0064] In contrast, in step S13, when the selection unit 113 determines that the vehicle speed V is greater than the second threshold Th2, the process moves to step S15.

[0065] In step S15, the selection unit 113 selects both the first map 111 and the second map 112, and outputs target acceleration / deceleration corresponding to the workshop distance and relative speed from the first map 111 and the second map 112. In the next step S16, the synthesis unit 114 synthesizes the target acceleration / deceleration output from the first map 111 and the target acceleration / deceleration output from the second map 112.

[0066] By conducting Figure 4The target acceleration / deceleration output unit 110 outputs the target acceleration / deceleration from the first mapping 111 when V≥Th1, outputs the target acceleration / deceleration from the second mapping 112 when V≤Th2, and outputs the target acceleration / deceleration after combining the target acceleration / deceleration output from the first mapping 111 and the target acceleration / deceleration output from the second mapping 112 when Th2<V<Th1.

[0067] Therefore, even if the same inter-vehicle distance and relative speed are input, the target acceleration / deceleration output unit 110 of this embodiment will output different target acceleration / deceleration (actually different target accelerations) according to the vehicle speed.

[0068] For example, if the first threshold Th1 is set to 30 km / h and the second threshold is set to 20 km / h, then the target acceleration / deceleration of the second mapping 112 is used in the speed range below 20 km / h, which is the speed at which the vehicle is stopped or approaching a stop; the target acceleration / deceleration of the first mapping 111 is used in the speed range above 30 km / h; and the target acceleration / deceleration of the first mapping 111 and the second mapping 112 is used in the speed range between them.

[0069] Here, the second mapping 112, used in the speed range of stopping or approaching stopping, stores target acceleration values ​​that are greater than those of the first mapping 111 for the same inter-vehicle distance and relative speed. As a result, when the vehicle 1 is at a speed of stopping or approaching stopping, a larger target acceleration value is output even when the same inter-vehicle distance and relative speed are input, compared to the case where it is traveling at a greater speed.

[0070] In this embodiment, it can be said that the insufficient torque during acceleration from a stop or near-stop speed is compensated by increasing the target acceleration and deceleration.

[0071] Furthermore, by performing the synthesis process as described in steps S15 and S16, the abrupt changes in target acceleration and deceleration during the switching between the first mapping 111 and the second mapping 112 can be suppressed.

[0072] The synthesis unit 114 can, for example, synthesize the outputs of the first mapping 111 and the second mapping 112 by weighted summing based on the vehicle speed. That is, when the vehicle speed is close to the first threshold Th1 (30 km / h), the target acceleration / deceleration of the first mapping 111 is multiplied by a larger weighting coefficient and then weighted summed; when the vehicle speed is close to the second threshold Th2 (20 km / h), the target acceleration / deceleration of the second mapping 112 is multiplied by a larger weighting coefficient and then weighted summed.

[0073] Furthermore, although the structure of the first mapping 111 and the second mapping 112 was considered to be implemented using a single mapping, the original mapping used to output the target acceleration and deceleration was a 3D mapping that output the target acceleration and deceleration corresponding to the vehicle distance and relative speed. Therefore, if it is necessary to further change the target acceleration and deceleration according to the vehicle's speed, a 4D mapping would be required, which is difficult to implement.

[0074] The structure of this embodiment can change the target acceleration or deceleration (target acceleration) through a simple structure and based on the inter-vehicle distance, relative speed, and vehicle speed.

[0075] (3) Effects of the implementation method

[0076] As explained above, according to this embodiment, the target acceleration / deceleration output unit 110 includes: a first mapping 111 storing a first target acceleration corresponding to the vehicle distance and relative speed; a second mapping 112 storing a second target acceleration corresponding to the vehicle distance and relative speed and greater than the first target acceleration with respect to the vehicle distance and relative speed; and a selection unit 113 selecting to use the output of the first mapping 111 and / or the output of the second mapping 112 according to the vehicle speed.

[0077] Therefore, the insufficient torque during acceleration from a stop or near-stop speed can be compensated by increasing the target acceleration and deceleration, thus enabling a driving assistance device 30 that can smoothly accelerate from a stop or near-stop speed.

[0078] The driving assistance device 30 of this embodiment is particularly effective for vehicles with drive systems that require greater torque when accelerating from a stop or near-stop speed compared to when accelerating from a normal driving speed.

[0079] The above-described embodiments are merely one example of specific implementations of the present invention, and the scope of the invention should not be limited by these embodiments. That is, the present invention can be implemented in various forms without departing from its spirit or main features.

[0080] In the above embodiments, the case where the vehicle 1 to which the driving assistance device of the present invention is applied is a tractor unit that can be connected to a trailer 2 for towing has been described, but the vehicles to which the present invention can be applied are not limited to this, and may also be passenger cars or other vehicles.

[0081] This application is based on Japanese patent application (Japanese Patent Application No. 2020-33773) filed on February 28, 2020, the contents of which are incorporated herein by reference in their entirety.

[0082] Industrial availability

[0083] The driving assistance device disclosed herein is useful in vehicles with drive systems that require greater torque when accelerating from a stop or near-stop speed compared to when accelerating from a normal driving speed.

[0084] Symbol Explanation

[0085] 1 vehicle

[0086] 2 trailers

[0087] 3. Vehicle body

[0088] 10 Drive System

[0089] 11 Engine

[0090] 12 Clutch

[0091] 13. Transmission

[0092] 14 propulsion shafts

[0093] 15 Differential device

[0094] 16 drive shafts

[0095] 17 wheels

[0096] 18 Engine ECU

[0097] 19. ECU for power transmission

[0098] 20 Braking System

[0099] 21 Commonly Used Brakes

[0100] 22 Reducer

[0101] 23 Exhaust Brake

[0102] 24 Braking ECU

[0103] 30 Driving assistance devices

[0104] Workshop 101 is located near the testing department.

[0105] 102 Relative Velocity Detection Unit

[0106] 110 Target Acceleration / Deceleration Output Unit

[0107] 111 First Mapping

[0108] 112 Second Mapping

[0109] 113 Selection Department

[0110] 114 Synthesis Department

Claims

1. A driving assist apparatus that assists driving of a vehicle, the driving assist apparatus comprising: an inter-vehicle distance detecting section that detects an inter-vehicle distance of a host vehicle from a preceding vehicle; a relative speed detecting section that detects a relative speed of the host vehicle from the preceding vehicle; and a target acceleration / deceleration output section that outputs a target acceleration / deceleration of the host vehicle based on the inter-vehicle distance and the relative speed, the target acceleration / deceleration output section including: a first map in which a first target acceleration corresponding to the inter-vehicle distance and the relative speed is stored; a second map in which a second target acceleration corresponding to the inter-vehicle distance and the relative speed is stored, and which is greater than the first target acceleration with respect to the inter-vehicle distance and the relative speed; and a selection section that selects an output of the first map when a host vehicle speed is equal to or greater than a first threshold value, and selects an output of the second map when the host vehicle speed is less than the first threshold value.

2. The driving assist apparatus according to claim 1, wherein the selection section selects the output of the first map when the host vehicle speed is equal to or greater than the first threshold value, selects the output of the second map when the host vehicle speed is equal to or less than a second threshold value that is less than the first threshold value, and selects the outputs of the first map and the second map when the host vehicle speed is less than the first threshold value and greater than the second threshold value, the target acceleration / deceleration output section further has a combining section that combines the outputs of the first map and the second map when the host vehicle speed is less than the first threshold value and greater than the second threshold value.

3. The driving assist apparatus according to claim 2, wherein the combining section combines the outputs of the first map and the second map by weighted addition of the outputs of the first map and the second map based on the host vehicle speed. ​

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