JP2017165216A - Vehicle travel control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To appropriately prevent lane deviation to a curve outside and contact with an obstacle, and keep a vehicle in a lane by considering a driving state of the vehicle and an actuation state of vehicle behavior control.SOLUTION: In an automatic driving state, in the case when at least one of hazardous situations of deviation from a lane division line on the outer side of a curve in a travel lane and contact with an obstacle such as an oncoming car, is detected, when the sideslip prevention control of a brake control device 22 is actuated so as to make a vehicle turn toward the outer side of a curve, vehicle behavior control of turning the vehicle toward the outer side of the curve in the sideslip prevention control of the brake control device 22 is stopped, and the brake control device 22 is made to execute emergency avoidance control of turning the vehicle toward the inner side of a curve. In the emergency avoidance control, a braking force for decelerating speed of the vehicle is added, and further, target steering torque by which the inner side of the curve becomes a target steering angle is calculated to perform steering control.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a travel control device for a vehicle that avoids lane departure and contact with an obstacle when a skid prevention device is activated in a vehicle having an automatic driving function.

  In recent years, in vehicles, various technologies related to automatic driving control have been developed and put into practical use so that drivers can drive more comfortably and safely. For example, in Japanese Patent Application Laid-Open No. 2001-114081 (hereinafter referred to as Patent Document 1), a collision determination device that detects an obstacle and determines whether or not to collide with the obstacle, and a lane that is currently traveling by detecting a lane. In a vehicle equipped with a lane departure judging device for judging whether or not to deviate, if it is estimated that the vehicle will collide with an obstacle or deviate from the lane even during the steering stability control, A technology of an automatic braking device that performs automatic braking by stopping control is disclosed.

JP 2001-114081 A

  However, in the technology of the automatic braking device disclosed in Patent Document 1 described above, how is steering stability control (for example, vehicle behavior control such as side slip prevention control) performed before the collision determination or the lane departure determination is performed? Since it is unknown whether the driver was operating and what kind of driving the driver was doing, simply stopping the vehicle behavior control and performing automatic braking prevents collisions with obstacles and lane departure. Therefore, there is a problem that it cannot be said to be sufficient to improve safety in consideration of the motion state and road surface condition of the vehicle at that time. For example, on a curved road with a low coefficient of friction, when the vehicle behavior control is trying to correct the oversteer tendency by adding a yaw moment so that it turns toward the outside of the curve, or when the driver is performing countersteer Even if the vehicle behavior control is stopped and automatic braking is performed, there is a possibility that the vehicle moves in the outer side of the curve while keeping the posture of the vehicle at that time and deviates from the front of the vehicle to the outer side of the curve or comes into contact with an obstacle.

  The present invention has been made in view of the above circumstances, and in consideration of the driving state of the vehicle and the operation state of the vehicle behavior control, it is possible to appropriately prevent the lane departure to the outside of the curve and the contact with the obstacle, and It is an object of the present invention to provide a vehicle travel control device that can be retained inside.

  One aspect of the vehicle travel control apparatus of the present invention is a travel environment information acquisition unit that acquires travel environment information in which the host vehicle travels, a travel information detection unit that detects travel information of the host vehicle, and the travel environment information described above. A vehicle behavior control means for controlling the turning motion of a vehicle by adding a yaw moment to the vehicle by a difference in braking / driving force of each wheel in the vehicle travel control device for executing automatic driving control based on the travel information of the host vehicle. , A dangerous state determination means for detecting a dangerous state of at least one of a deviation from a lane line outside the curve of the traveling lane and a contact with an obstacle, and the vehicle behavior control so that the vehicle turns toward the outside of the curve If the occurrence of the dangerous state is detected by the vehicle dangerous state determination means when the means is activated, the vehicle behavior control of turning toward the outside of the curve of the vehicle behavior control means is stopped. Allowed, and a emergency avoidance execution means for executing an emergency avoidance control for turning towards the curve inside the vehicle behavior control means.

  According to the vehicle travel control device of the present invention, in consideration of the driving state of the vehicle and the operation state of the vehicle behavior control, it is possible to appropriately prevent lane departure to the outside of the curve and contact with an obstacle, and It becomes possible to keep it on.

1 is an overall configuration diagram of a vehicle travel control device according to an embodiment of the present invention. It is a flowchart of the emergency avoidance control program at the time of automatic operation control by one Embodiment of this invention. It is explanatory drawing which shows an example of the characteristic of the emergency avoidance target yaw rate by one Embodiment of this invention. It is explanatory drawing of the motion of the vehicle which carries out emergency avoidance by one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In FIG. 1, reference numeral 1 denotes a vehicle travel control device. The travel control device 1 includes a travel control unit 10, a surrounding environment recognition device 11, a travel parameter detection device 12, a host vehicle position information detection device 13, Each input device of the inter-vehicle communication device 14, the road traffic information communication device 15, and the switch group 16, and the output devices of the engine control device 21, the brake control device 22, the steering control device 23, the display device 24, and the speaker / buzzer 25 are provided. It is connected.

  The surrounding environment recognition device 11 includes a camera device (stereo camera, monocular camera, color camera, etc.) provided with a solid-state imaging device or the like provided in a vehicle interior that captures image information by capturing an external environment of the vehicle, 1 is constituted by a radar device (laser radar, millimeter wave radar, etc.) for receiving a reflected wave from a three-dimensional object, sonar (not shown).

  The surrounding environment recognition device 11 performs, for example, a well-known grouping process on the distance information based on the image information captured by the camera device, and the three-dimensional road shape in which the grouping distance information is set in advance. Three-dimensional objects such as lane marking data, guardrails along the road, side walls such as curbs, vehicles (preceding vehicles, oncoming vehicles, parallel vehicles, parked vehicles) The (obstruction) data and the like are extracted together with the speed from the relative position (distance, angle) from the host vehicle.

  Further, the surrounding environment recognition device 11 detects the position (distance, angle) where the reflected three-dimensional object exists together with the speed based on the reflected wave information acquired by the radar device. Thus, the surrounding environment recognition device 11 is provided as a traveling environment information acquisition unit.

  The travel parameter detection device 12 is the travel information of the host vehicle, specifically, the vehicle speed, the longitudinal acceleration, the lateral acceleration, the steering torque, the steering wheel angle, the yaw rate, the accelerator opening, the throttle opening, and the road surface gradient of the traveling road surface, Estimated road surface friction coefficient, brake pedal switch on / off, accelerator pedal switch on / off, turn signal switch on / off, hazard lamp switch on / off, etc. are detected. Thus, the travel parameter detection device 12 is provided as travel information detection means.

  The own vehicle position information detection device 13 is, for example, a known navigation system, and receives, for example, a radio wave transmitted from a GPS (Global Positioning System) satellite and receives the radio wave information, an acceleration sensor, and a gyro. Detects the current position based on the information of the self-contained navigation based on the vehicle speed signal accompanying the rotation of the tire, and flash memory, CD (Compact Disc), DVD (Digital Versatile Disc), Blu-ray (registered trademark) disc The vehicle position is specified on map data stored in advance in a hard disk drive (HDD) or the like.

  The map data stored in advance includes road data and facility data. Road data includes link position information, type information, node position information, type information, curve curvature (curve radius) information, and information on the connection relationship between a node and a link, that is, intersection information, road branching, merging It includes point information and maximum vehicle speed information on branch roads. The facility data has a plurality of records for each facility, and each record includes the name information of the target facility, location information, facility type (department store, store, restaurant, parking lot, park, vehicle failure) It has data that shows information). When the vehicle position on the map position is displayed and a destination is input by the operator, a route from the departure point to the destination is calculated in a predetermined manner and displayed on a display device 24 such as a display or a monitor. In addition, the speaker / buzzer 25 can be guided by voice guidance. Thus, the own vehicle position information detection device 13 is provided as a travel environment information acquisition unit.

  The inter-vehicle communication device 14 is composed of, for example, a narrow-area wireless communication device having a communication area of about 100 [m] such as a wireless LAN, and directly communicates with other vehicles without passing through a server or the like to transmit and receive information. It is possible to do. And vehicle information, traveling information, traffic environment information, etc. are exchanged by mutual communication with other vehicles. The vehicle information includes specific information indicating the vehicle type (in this embodiment, the type of passenger car, truck, motorcycle, etc.). The traveling information includes vehicle speed, position information, brake lamp lighting information, blinking information of a direction indicator transmitted at the time of turning left and right, and blinking information of a hazard lamp blinking at an emergency stop. Furthermore, the traffic environment information includes information that varies depending on the situation such as road traffic congestion information and construction information. Thus, the inter-vehicle communication device 14 is provided as a travel environment information acquisition unit.

  The road traffic information communication device 15 is a so-called road traffic information communication system (VICS: Vehicle Information and Communication System: registered trademark), and is used for FM congestion broadcasting, a transmitter on the road, congestion, accidents, construction, required time, parking. The road traffic information of the car park is received in real time, and the received traffic information is displayed on the previously stored map data. Thus, the road traffic information communication device 15 is provided as a travel environment information acquisition unit.

  The switch group 16 is a switch group related to the driver's driving support control. For example, the switch group 16 is a switch that controls traveling at a constant speed that is set in advance, or a distance between the preceding vehicle and an inter-vehicle time are set in advance. A switch for keeping track at a constant value, a lane keeping control switch for driving control while maintaining the driving lane at the set lane, a lane departure preventing control switch for preventing departure from the driving lane, and preceding Passing control execution permission switch for executing overtaking control of vehicles (vehicles to be overtaken), switch for executing automatic driving control for performing all these controls in cooperation, vehicle speed, inter-vehicle distance, inter-vehicle distance required for each control It consists of a switch for setting time, speed limit, etc., or a switch for canceling each control.

  The engine control device 21 uses, for example, a fuel for a vehicle engine (not shown) based on the intake air amount, throttle opening, engine water temperature, intake air temperature, oxygen concentration, crank angle, accelerator opening, and other vehicle information. This is a known control unit that performs main control such as injection control, ignition timing control, and control of an electronically controlled throttle valve. Further, when a predetermined slip occurs in the drive wheel, the engine control device 21 reduces the driving force (torques down) so that the tire slip rate becomes a preset target slip rate, for example, a well-known traction. Configured to run the control. The engine control device 21 receives the above-described automatic driving control (collision prevention control with obstacles, constant speed driving control, following driving control, lane keeping control, When an acceleration (requested acceleration) required for lane departure prevention control, other overtaking control, etc.) is input, a drive torque (automatic driving request torque) is calculated based on the required acceleration, and the automatic driving request torque is calculated. The engine is controlled to the target torque.

  The brake control device 22 controls a four-wheel brake device (not shown) independently of a driver's brake operation based on, for example, a brake switch, four-wheel wheel speed, steering wheel angle, yaw rate, and other vehicle information. The yaw moment to be added to the vehicle such as the known ABS control or the side slip prevention control as a vehicle behavior control means for controlling the turning motion of the vehicle by adding the yaw moment to the vehicle by the difference in braking / driving force of each wheel. This is a known control unit that performs yaw brake control.

  For example, in the skid prevention control, the target yaw rate of the vehicle is calculated based on the steering angle and the vehicle speed, and the target yaw rate is compared with the actually generated yaw rate, and the absolute value of the target yaw rate is the absolute value of the actual yaw rate. If it is smaller than the predetermined value, the vehicle is judged to have an oversteer tendency and braking force is applied to the turning outer wheel of the vehicle. Conversely, if the absolute value of the target yaw rate is greater than the absolute value of the actual yaw rate by a predetermined value or more, it is determined that the vehicle has an understeer tendency and braking force is applied to the turning inner wheel of the vehicle to Stabilization of directional behavior is planned.

  Further, the brake control device 22 receives the above-mentioned automatic driving control (collision prevention control with obstacles, constant speed driving control, following driving control, lane keeping control, When the necessary deceleration (required deceleration) for lane departure prevention control, other overtaking control, etc.) is input, the target hydraulic pressure of the wheel cylinder of each wheel brake is set based on the required deceleration, Perform brake control.

  The steering control device 23 controls the assist torque by an electric power steering motor (not shown) provided in the vehicle steering system based on, for example, vehicle speed, steering torque, steering wheel angle, yaw rate, and other vehicle information. It is a control device. In addition, the steering control device 23 maintains the above-mentioned traveling lane in the set lane and performs lane keeping control for performing traveling control, lane departure preventing control for performing departure prevention control from the traveling lane, and automatic driving steering for executing these in coordination. The steering angle or steering torque required for these lane keeping control, lane departure prevention control, and automatic driving steering control is calculated by the traveling control unit 10 and input to the steering control device 23. The electric power steering motor is driven and controlled in accordance with the input control amount.

  The display device 24 is a device that provides a visual warning and notification to drivers such as a monitor, a display, and an alarm lamp. The speaker / buzzer 25 is a device that gives an audible warning and notification to the driver.

  Then, the traveling control unit 10 is configured to prevent collisions with obstacles, constant speed traveling control, follow-up traveling control, lane keeping control, lane departure prevention control based on the input signals from the devices 11 to 16 described above. In addition, automatic driving control or the like is executed by performing overtaking control or the like in cooperation. In the automatic driving state, the traveling control unit 10 detects, for example, when the side slip prevention control of the brake control device 22 is activated so that the vehicle turns toward the outside of the curve in order to correct the oversteer tendency of the vehicle. The behavior of the vehicle turning toward the outside of the curve of the anti-slip control of the brake control device 22 when at least one dangerous state of deviation from the lane marking outside the curve and contact with an obstacle such as an oncoming vehicle is detected. The control is stopped, and the emergency avoidance control that allows the brake control device 22 to turn toward the inside of the curve and to allow the spin tendency of the vehicle is executed. In this emergency avoidance control, a braking force that decelerates the vehicle is added. Further, in the emergency avoidance control, a target steering torque in which the inside of the curve becomes the target steering angle is calculated and output to the steering control device 23 to perform the steering control. As described above, the travel control unit 10 is provided as a dangerous state determination unit and an emergency avoidance execution unit.

  Next, an emergency avoidance control program at the time of automatic driving control executed by the travel control unit 10 will be described with reference to the flowchart of FIG.

  First, in step (hereinafter abbreviated as “S”) 101, it is determined whether or not the vehicle is in an automatic operation state.

  When the routine proceeds to S102, it is determined whether or not the side slip prevention control of the brake control device 22 is operating so as to turn the vehicle toward the outside of the curve in order to correct the oversteer tendency of the vehicle, for example. If yes, exit the program and if it is running, go to S103.

  In S103, the collision margin time tttc is calculated by the following equation (1), for example.

tttc = L / Vr (1)
Here, L is a relative distance between an obstacle such as a lane line outside the curve or an oncoming vehicle and the own vehicle on an expected traveling path of the own vehicle (for example, a traveling path when the vehicle travels in a straight line). It is. Further, Vr is a relative speed between the lane marking line outside the curve or an obstacle such as an oncoming vehicle and the host vehicle.

  Next, in S104, the collision allowance time tttc is compared with the threshold value tc set in advance by experiment, calculation, or the like.

  As a result of the comparison in S104, if it is determined that the collision allowance time tttc is greater than or equal to the threshold value tc (ttcc ≧ tc), a dangerous state (departure from the lane line outside the curve or contact with an obstacle such as an oncoming vehicle) It is determined that there is no possibility, and the program is exited.

  Conversely, when it is determined that the collision allowance time tttc is shorter than the threshold value tc (tttc <tc), a dangerous state (possibility of deviation from the lane line outside the curve or contact with an obstacle such as an oncoming vehicle) And the process proceeds to S105.

  In S105, the driver visually and audibly warns and informs the driver that the emergency avoidance traveling is to be executed by the display device 24 and the speaker / buzzer 25 in the vehicle. In addition, for the outside of the vehicle, a warning lamp is flashed or a brake lamp is turned on to notify the surroundings that the emergency avoidance traveling is to be executed and to call attention.

  Next, the process proceeds to S106, and the side slip prevention control of the brake control device 22 is turned off.

  Next, proceeding to S107, the emergency avoidance target yaw rate γt at the time of emergency avoidance is set with reference to a characteristic map as shown in FIG. In the example of FIG. 3, the emergency avoidance target yaw rate γt is set according to the vehicle speed V and the curve radius ρ, but is further corrected and obtained by the road surface friction coefficient μ, the road surface gradient, and the like. Also good.

Next, the process proceeds to S108, and the braking force of each wheel (the turning outer front wheel braking force Fbof, the turning outer rear wheel braking force Fbor, the turning inner front wheel braking force Fbif, and the turning inner rear wheel braking force Fbir is determined by, for example, (2) , (3), (4), and (5) are calculated and output to the brake control device 22.
Fbof = Cbf · (1/2) · Fbb (2)
Fbor = (1-Cbf). (1/2) .Fbb (3)
Fbif = Cbf · (1/2) · Fbb + Cbmf · Fbm (4)
Fbir = (1-Cbf). (1/2) .Fbb + (1-Cbmf) .Fbm (5)
Here, Fbb is a braking force for decelerating the vehicle set in advance by experiment, calculation, etc., and Cbf is a front wheel side distribution ratio of the braking force.

  Fbm is a braking force for generating a yaw moment in the vehicle, and is calculated by, for example, the following equation (6).

Fbm = Kb · | γt−γ | (6)
Here, γ is an actual yaw rate detected by a yaw rate sensor or the like, and Kb is a conversion gain (predetermined value) to the braking force. Cbmf is a front wheel side distribution ratio set in advance by experiments, calculations, etc., of the braking force that generates the yaw moment.

  That is, in this S108, as is apparent from the equations (2) to (5), according to the present embodiment, the vehicle is applied with the braking force Fbm to the wheel on the inside of the turn, and the vehicle spins. The turning force to the inside of the turning which allows the tendency is increased, and the braking force Fbb is added to decelerate.

  Next, the process proceeds to S109, and the target steering torque Tt is calculated by, for example, the following expression (7) and output to the steering control device 23.

Tt = Kstr · | γt−γ | (7)
Here, Kstr is a gain set in advance by experiment, calculation or the like.

  That is, the steering control is performed so as to suppress the counter steer control performed by the steering wheel and to promote the control of the spin tendency by the brake control.

  Next, the process proceeds to S110, where the own vehicle speed V is compared with a preset threshold value VCL as to whether it can be considered that the vehicle is substantially stopped, and the own vehicle speed V is lower than the threshold value VCL (V <VCL), and the vehicle stops substantially. If it can be considered that the vehicle stays in the lane, the process proceeds to S111, the emergency avoidance control is terminated, and the program exits. If V ≧ VCL, the processing from S107 is repeated.

  An example of the emergency avoidance control during the above automatic driving control will be described with reference to FIG.

  First, when turning the curve, if the vehicle tends to oversteer (P1 in FIG. 4), yaw moment is added to the vehicle so as to turn toward the outside of the curve by the side slip prevention control ( The state of P2 in FIG. 4). At this time, depending on the steering state (for example, in the case of a counter-steer state), the road surface friction coefficient μ, and the vehicle speed V, as shown in the state of P2 ′ in FIG. There is a possibility that deviation from the outside lane line or contact with an obstacle such as an oncoming vehicle may occur. Therefore, in such a condition, as shown in the state of P3 in FIG. 4, the vehicle behavior control that turns toward the outside of the side slip prevention control curve is stopped and the vehicle turns toward the inside of the curve. The emergency avoidance control that allows the spin tendency is executed, and the emergency avoidance control that keeps the vehicle in the lane is performed, as indicated by P4 in FIG.

  Thus, according to the embodiment of the present invention, in the automatic driving state, for example, the side slip prevention control of the brake control device 22 is activated so that the vehicle turns toward the outside of the curve in order to correct the oversteer tendency of the vehicle. If at least one dangerous state of deviation from the lane marking outside the curve of the traveling lane and contact with an obstacle such as an oncoming vehicle is detected, the outside of the curve of the side slip prevention control of the brake control device 22 is detected. The vehicle behavior control that turns toward the vehicle is stopped, and the brake control device 22 is caused to execute emergency avoidance control that turns toward the inside of the curve and also allows the vehicle to have a spin tendency. In this emergency avoidance control, a braking force for decelerating the vehicle is added, and further, a target steering torque with the inside of the curve as the target steering angle is calculated and output to the steering control device 23 for steering control. For this reason, in consideration of the driving state of the vehicle and the operation state of the vehicle behavior control, it is possible to appropriately prevent the vehicle from deviating to the outside of the lane or coming into contact with an obstacle while facing forward, and to keep the vehicle in the lane. It becomes possible to keep it on.

  In this embodiment, in order to dare to make the vehicle have a spin tendency, the braking force according to the above-described equations (2) to (5) is applied to each wheel, but this spin tendency is further promoted. Therefore, in order to increase the slip ratio of the rear wheel, a predetermined braking force may be applied to the rear wheel to control the rear wheel to be locked.

DESCRIPTION OF SYMBOLS 1 Traveling control apparatus 10 Traveling control part (dangerous state determination means, emergency avoidance execution means)
11 Ambient environment recognition device (traveling environment information acquisition means)
12 Travel parameter detection device (travel information detection means)
13 Self-vehicle position information detection device (running environment information acquisition means)
14 Vehicle-to-vehicle communication device (running environment information acquisition means)
15 Road traffic information communication device (traveling environment information acquisition means)
16 switch group 21 engine control device 22 brake control device (vehicle behavior control means)
23 Steering control device 24 Display device 25 Speaker buzzer

Claims (3)

Driving environment information acquisition means for acquiring driving environment information in which the host vehicle travels, driving information detection means for detecting driving information of the host vehicle, and automatic driving control based on the driving environment information and the driving information of the host vehicle. In the vehicle travel control device to be executed,
Vehicle behavior control means for controlling the turning motion of the vehicle by adding a yaw moment to the vehicle due to the braking / driving force difference of each wheel;
A dangerous state determination means for detecting a dangerous state of at least one of deviation from a lane line outside the curve of the traveling lane and contact with an obstacle;
When the vehicle behavior control means is actuated so that the vehicle turns toward the outside of the curve, if the occurrence of the dangerous state is detected by the vehicle danger state determination means, the vehicle behavior control means Emergency avoidance executing means for stopping the vehicle behavior control turning toward the vehicle and causing the vehicle behavior control means to execute emergency avoidance control turning toward the inside of the curve;
A travel control device for a vehicle, comprising:   2. The vehicle travel control apparatus according to claim 1, wherein the emergency avoidance execution unit adds a braking force for decelerating the vehicle during the emergency avoidance control.   2. The emergency avoidance executing means, during the emergency avoidance control, sets a target steering angle inside the curve and performs steering control of the steering means so as to be the target steering angle. The vehicle travel control apparatus according to claim 2.

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