Vehicle travel assistance method and device

Abstract

The present invention: plans a traveling track and a traveling velocity of a vehicle; when an obstacle has been detected ahead in the traveling direction, estimates a possibility of a contact between the vehicle and the obstacle; when the contact is estimated to be possible and when braking and / or steering the vehicle to avoid contact, calculates a necessary braking force which is necessary for the vehicle to stop before the position where the vehicle comes into contact with the obstacle, on the basis of the traveling velocity of the vehicle and the distance on the traveling track between the current position of the vehicle and the position where the vehicle comes into contact with the obstacle; calculates a necessary lateral force which is necessary for the vehicle to travel along the traveling track; determines whether or not the necessary braking force and the necessary lateral force can be concurrently generated by means of tires of the vehicle; when it is determined that the necessary braking force and the necessary lateral force cannot be concurrently generated, sets a modified traveling track on which the vehicle travels so that the lateral force becomes smaller than the necessary lateral force; and brakes and / or steers the vehicle on the basis of the necessary braking force and the modified traveling track to thereby avoid contact.

Description

Vehicle driving support method and device

[0001] The present invention relates to a vehicle driving assistance method and device.

[0002] For example, in autonomous driving, a controller mounted on a vehicle plans a travel trajectory and travel speed of the vehicle and controls a steering device, a drive source, a braking device, etc. so that this travel trajectory and travel speed are achieved. In this way, when a vehicle is traveling on a predetermined travel trajectory at a predetermined travel speed, if there is an obstacle ahead in the travel direction and contact (collision) with the obstacle is predicted, the vehicle must be braked and / or steered to avoid contact. Patent Document 1 below sets a steering assistance area in which contact with a forward obstacle is avoided by steering, and a deceleration assistance area in which contact is avoided by braking, and if an obstacle is present in an interference area where the two areas overlap, avoidance by braking (deceleration) is prioritized over avoidance by steering.

[0003] Japanese Patent Application Laid-Open No. 2021-169247

[0004] However, for example, if a pedestrian appears on the roadway (in the lane) as an obstacle ahead while the vehicle is turning, if avoidance by braking is prioritized over avoidance by steering as in Patent Document 1, the achievable braking force will be small due to the lateral force associated with turning, and as a result, there is a risk that the braking distance will be insufficient and the vehicle will get too close to the obstacle ahead. An object of the present invention is to provide a vehicle driving assistance method and device that can avoid contact with an obstacle ahead in the driving direction even while the vehicle is turning.

[0005] One aspect of the present invention is to plan a vehicle's travel trajectory and travel speed, and when an obstacle is detected ahead in the travel direction, predict the possibility of contact between the vehicle and the obstacle, and when the possibility of contact is predicted and the vehicle is braked and / or steered to avoid contact, calculate the required braking force required for the vehicle to stop just before the position at which it will contact the obstacle based on the distance on the travel trajectory from the vehicle's current position to the position at which it will contact the obstacle and the vehicle's travel speed, calculate the required lateral force required for the vehicle to travel along the travel trajectory, determine whether the vehicle's tires can generate the required braking force and the required lateral force simultaneously, and if it is determined that they cannot be generated simultaneously, set a corrected travel trajectory for the vehicle to travel so that the lateral force is smaller than the required lateral force, and brake and / or steer the vehicle based on the required braking force and the corrected travel trajectory to avoid contact.

[0006] According to one aspect of the present invention, a corrected driving trajectory is set so that the lateral force is smaller than the required lateral force, and the vehicle is braked and / or steered based on the corrected driving trajectory and the required braking force, thereby making it possible to avoid contact with an obstacle ahead in the driving direction. The objects and advantages of the present invention are realized and achieved by using the elements and combinations thereof set forth in the claims. It should be understood that both the foregoing general description and the following detailed description are merely exemplary and explanatory and are not intended to limit the invention as defined by the claims.

[0007] It is a plan view showing a schematic configuration of an example of a vehicle driving assistance system of an embodiment. It is a flowchart showing an example of calculation processing performed by the automatic driving controller of Figure 1. It is an explanatory diagram of an action by the calculation processing of Figure 2. It is an explanatory diagram of an action by the calculation processing of Figure 2. It is an explanatory diagram of an action by the calculation processing of Figure 2. It is an explanatory diagram of an action by the calculation processing of Figure 2. It is an explanatory diagram of an action by the calculation processing of Figure 2.

[0008] The vehicle driving assistance system of the embodiment shown in FIG. 1 is configured with brake devices and steering devices that enable automatic driving. The brake devices 2 provided on the front wheels 1F and rear wheels 1R are so-called disc brakes that apply braking by clamping brake pads 22 against disc rotors (rotors) 21 attached to the wheels. Each brake device 2 has a brake pad 22 immobilely disposed on one end face of the rotor 21 within a caliper, and a brake pad 22 disposed on the opposite end face presses against the rotor 21 to generate braking force. To this end, a piston is disposed within the caliper that reciprocates in the direction of contact and separation between the brake pad 22 and the rotor 21 in response to hydraulic pressure (hydraulic pressure). This piston moves in the direction of pressing the brake pad 22 against the rotor 21 when hydraulic pressure applied to a pressure-receiving surface opposite the brake pad 22 side is positive (pressurized). In other words, each brake device 2 has a hydraulic brake mechanism.

[0009] In this embodiment, to enable automatic driving, an electric booster 3 is used as a hydraulic pressure generating device that generates hydraulic pressure to the pistons of each brake device 2. The electric booster 3 is a hydraulic pump driven by an electric motor (electric actuator) (not shown), and is capable of increasing the hydraulic pressure to a positive pressure on the pistons of each brake device 2. Positive pressure is generally a state in which the pressure is greater than atmospheric pressure. When the electric motor is not driven, the hydraulic pressure is equal to atmospheric pressure. In this embodiment, the electric booster 3 is mechanically or hydraulically connected to the brake pedal 23, and is configured to output positive hydraulic pressure corresponding to the amount of depression of the brake pedal 23 when the brake pedal 23 is depressed. The operating state of the electric booster 3 is controlled by a hydraulic pressure controller 5.

[0010] A hydraulic pressure control device 4 is interposed between the hydraulic pressure output side of the electric booster 3 and the brake device 2 of each wheel, and is capable of individually adjusting the hydraulic pressure to the brake device 2 of each wheel. This hydraulic pressure control device 4 can individually maintain, reduce, or increase the hydraulic pressure of the brake device 2 of each wheel, thereby applying braking force to each wheel and increasing or decreasing that braking force. Specifically, it has a hydraulic pressure control function equivalent to that of an anti-skid control system (ABS) that reduces the tendency of the wheels to lock, or a vehicle dynamics control system (VDC) that adjusts the vehicle behavior expressed by the yaw rate and lateral acceleration. This hydraulic pressure control device 4 can adjust the hydraulic pressure of the brake device 2 of each wheel regardless of the hydraulic pressure output from the electric booster 3. However, for example, a switching valve provided in the hydraulic pressure control device 4 can connect (directly connect) the brake device 2 of each wheel to the electric booster 3 or disconnect it from the electric booster 3. That is, when the brake device 2 is directly connected to the electric booster 3, the output hydraulic pressure of the electric booster 3 is directly supplied to the brake device 2, and when the brake device 2 is disconnected from the electric booster 3, the hydraulic pressure of the brake device 2 can be adjusted individually by the hydraulic pressure control device 4. The operating state of this hydraulic pressure control device 4 is also controlled by the hydraulic pressure controller 5.

[0011] In this embodiment, the braking force of each brake device 2 can be adjusted using hydraulic pressure, so the hydraulic pressure controller 5 can be read as a braking force controller. Like the automatic driving controller 8 described below, the hydraulic pressure controller 5 is constructed as a computer system equipped with advanced arithmetic processing and storage functions. During normal driving (non-automatic driving), the hydraulic pressure controller 5 controls the operation state of the hydraulic pressure control device 4 so that hydraulic pressure corresponding to the depression (push force) of the brake pedal 23 is supplied to the brake device 2, and also controls the operation state of the hydraulic pressure control device 4 so that hydraulic control functions such as the ABS and VDC described above are achieved. During automatic driving, the hydraulic pressure controller 5 controls the operation states of the electric booster 3 and the hydraulic pressure control device 4 so that the required braking force Fx commanded by the automatic driving controller 8 is achieved. While the hydraulic brake device 2 applies braking force to each wheel using hydraulic pressure, an electric brake device that applies braking force to each wheel using an electric motor can also be used instead of the hydraulic brake device 2. In this case, braking force can be electronically controlled without using the hydraulic pressure control device 4 or the hydraulic booster 3.

[0012] The vehicle also includes an electric steering actuator 6 that steers the front wheels 1F, which are steerable wheels, as a steering device that enables automatic driving. An existing rack-and-pinion or column-type electric steering actuator using an electric motor can be used as the electric steering actuator 6. The operation state of the electric steering actuator 6 is controlled by a steering controller 7. Like the automatic driving controller 8 described below, the steering controller 7 is constructed as a computer system with advanced arithmetic processing and storage functions. During normal driving (not automatic driving), the steering controller 7 controls the operation state of the steering actuator 6 so that a steering angle of the front wheels 1F corresponding to the steering angle of the steering wheel 24 is achieved. During automatic driving, the steering controller 7 controls the operation state of the steering actuator 6 so that a steering angle corresponding to the vehicle turning limit radius r commanded by the automatic driving controller 8 is achieved.

[0013] As described above, the vehicle is provided with an automatic driving controller 8 for enabling automatic driving. For example, the automatic driving controller 8 works in conjunction with a navigation system (not shown) to achieve a driving state appropriate for the driving route, and performs well-known control functions such as vehicle-following control, obstacle avoidance control, and constant-speed driving control. Specifically, the automatic driving controller 8 controls the operating states of drive sources such as an engine and electric drive motor (not shown) and the steering state of steered wheels by a steering device, and outputs necessary control commands to a drive source controller (not shown) and a steering controller 7. Therefore, the vehicle is provided with control input acquisition means such as various sensors, cameras (image capture devices), and distance meters required for automatic driving. If it becomes necessary to decelerate the vehicle during automatic driving, the necessary braking force to achieve the required deceleration for the vehicle is output to the hydraulic controller 5. Furthermore, to enable normal driving that is not automatic driving, an accelerator pedal 25 is provided as an acceleration / deceleration input means, similar to existing vehicles.

[0014] In autonomous driving, the vehicle's travel trajectory and travel speed are planned in advance. This plan is called a driving behavior plan. To prepare this driving behavior plan, the vehicle is equipped with a positioning device 9 that detects the vehicle's position and attitude, a surroundings recognition device 10 that detects the positions and attitudes of objects around the vehicle, and high-precision map data 11. The positioning device 9 is configured, for example, with a Global Positioning System (GPS) receiver and receives radio waves from multiple navigation satellites to measure the vehicle's current position. The surroundings recognition device 10 is configured, for example, with a radar and a camera and detects the presence and distance of objects around the vehicle, particularly obstacles near the vehicle and vehicles ahead, and detects the lane the vehicle is traveling in from lane markers on the road. The high-precision map data 11 includes, for example, road-specific information, such as road node information indicating reference points on road reference lines (e.g., road center lines) and road link information indicating the road section configurations between road nodes.

[0015] A driving action plan is a lane-level driving action plan for a medium- to long-distance range that specifies the driving lane in which the vehicle will travel and the driving actions required to travel in that lane. To achieve this, a route space map representing the route around the vehicle and the presence or absence of objects, and a risk map quantifying the risk level of the driving area, are generated based on the vehicle's position and attitude, the positions and attitudes of objects around the vehicle, and a high-precision map. Using this route space map and risk map, a driving action plan is generated for the vehicle to automatically travel along a predetermined planned route. If it is determined that another vehicle is approaching the vehicle, a driving action plan is generated that includes stopping or decelerating the vehicle or evasive steering. Then, based on this driving action plan, the vehicle's motion characteristics, and the route space map, candidate driving trajectories and speed profiles for the vehicle are generated. The future risk of each candidate is evaluated based on the risk map, and the optimal driving trajectory and speed profile are selected and set as the target driving trajectory and target speed profile for the vehicle.

[0016] The autonomous driving controller 8 is an electronic control unit (ECU) that performs the above-described arithmetic processing and the arithmetic processing described below and outputs control commands to, for example, the hydraulic controller 5 and the steering controller 7. Therefore, the autonomous driving controller 8 includes a computer system with advanced arithmetic processing capabilities. Like well-known computer systems, this computer system includes a processor 12 that exhibits advanced arithmetic processing capabilities and a storage device 13 that stores information such as programs and sensor signals. The processor 12 includes, for example, a central processing unit (CPU) or a microprocessing unit (MPU). The storage device 13 includes a semiconductor storage device, a magnetic storage device, and an optical storage device. The storage device 13 may further include a register, a cache memory, and a memory used as a main storage device. The arithmetic processing performed by the autonomous driving controller 8 is realized, for example, by the processor 12 executing a computer program stored in the storage device 13 of the autonomous driving controller 8. The arithmetic processing performed by the autonomous driving controller 8 may also be performed by a functional logic circuit configured in a general-purpose semiconductor integrated circuit. For example, the autonomous driving controller 8 may have a programmable logic device such as a field programmable gate array. Note that other controllers have equivalent configurations and functions. Controllers can also share data and communicate with each other.

[0017] Next, the calculation process executed in the autonomous driving controller 8 will be described using the flowchart of FIG. 2 . This calculation process is intended to avoid contact with a pedestrian, bicycle, or motorcycle, i.e., an obstacle ahead, if such a pedestrian, bicycle, or motorcycle suddenly appears in the lane in which the vehicle is traveling. It is executed, for example, at a predetermined sampling period. In autonomous driving, a driving speed is planned based on the risk map described above, allowing the vehicle to sufficiently decelerate and stop in response to predictable risks. However, it is often impossible to predict the sudden appearance of a pedestrian, bicycle, or motorcycle in the lane in which the vehicle is traveling. This calculation process aims to avoid contact with such an obstacle ahead. In this calculation process, first, in step S1, vehicle (host vehicle) information and surrounding environment information are acquired. Next, the process proceeds to step S2, where it is determined whether or not there is an obstacle (pedestrian, bicycle, or motorcycle) ahead of the vehicle's traveling path (lane). If there is an obstacle ahead, the process proceeds to step S3; otherwise, the process returns.

[0018] In step S3, the required braking force Fx required to avoid contact with an obstacle ahead of the vehicle is calculated. In order to avoid contact with an obstacle ahead, such as a pedestrian, bicycle, or motorcycle that has jumped into the lane, a braking force is required to stop the vehicle in front of the obstacle along the vehicle's travel path to the obstacle ahead. Details will be described later. Next, the process proceeds to step S4, where the achievable lateral force Fy for achieving the required braking force Fx is calculated from the tire friction circle model. Details will be described later. Next, the process proceeds to step S5, where the vehicle turning limit radius r is calculated from the calculated achievable lateral force Fy and the traveling speed v. Details will be described later. Next, the process proceeds to step S6, where the maximum allowable turning radius r for the current traveling road (lane) is calculated. ｍａｘ is acquired from, for example, the high-precision map data 11. This maximum allowable turning radius r ｍａｘ is the maximum turning radius at which the vehicle does not deviate from the lane it is traveling in during the distance on the travel trajectory up to that point, assuming that the vehicle stops in front of an obstacle ahead.

[0019] Next, the process proceeds to step S7, where it is determined from the surrounding environment information whether or not there is an obstacle on the outside of the turning lane of the current driving path (lane). If there is an obstacle on the outside of the turning lane, the process proceeds to step S8, and if not, the process proceeds to step S10. In step S8, the vehicle turning restriction radius r is calculated based on the maximum allowable turning radius r. ｍａｘ It is determined whether the vehicle turning restriction radius r is greater than the maximum allowable turning radius r ｍａｘ If it is greater than the maximum allowable turning radius r, the process proceeds to step S9, otherwise the process proceeds to step S10. ｍａｘ On the other hand, in step S10, the vehicle turning restriction radius r is set as the vehicle turning restriction radius r as it is, and then the process proceeds to step S11. In step S11, the vehicle turning restriction radius r is output to the steering controller 7, and the required braking force Fx is output to the hydraulic pressure controller 5, and then the process returns.

[0020] Next, the required braking force Fx calculated in step S3 of the calculation process in Figure 2, the achievable lateral force Fy calculated in step S4, and the vehicle turning restriction radius r calculated in step S5 will be described. Here, the flow of the calculation process in the flowchart will be ignored for the moment and the braking force that can be generated by a turning vehicle will be described. Figure 3(a) schematically shows a state in which a pedestrian has jumped into the lane in front of a vehicle while the vehicle is being automatically driven along a curved lane with a constant radius of curvature. In Figure 3 below, the tip of the arrow indicating the vehicle's traveling direction indicates the vehicle's stopping position. Since the current vehicle turning travel path is known in advance, if the turning radius is r and the traveling speed is v, the tire lateral force Fy is given by the following equation 1. In equation 1, the turning radius r is also solved. This turning radius r coincides with the radius of curvature at the center in the width direction of the lane on which the vehicle is traveling. Hereinafter, the turning radius of the current vehicle turning travel path will be referred to as the current turning radius r. Ｒ Let's say.

[0021] Current lateral force Fy Ｒ In the tire friction circle model shown in FIG. 4A, the braking force Fx that can be generated by the tire is the currently achieved braking force Fx ＲAssuming that the distance on the current turning travel path to the obstacle ahead, i.e., the pedestrian, on the travel path (hereinafter referred to as the travel path distance) L is acquired from the detection information of the surroundings recognition device 10, the braking force Fx required to stop the vehicle at this travel path distance L is given by the following two equations (where m is the mass of the vehicle and a is the acceleration (deceleration) until the vehicle stops) (the final velocity v ０ = 0). However, the currently achievable braking force Fx shown in FIG. Ｒ The current required travel distance L calculated by Ｒ If is greater than the actual travel distance L of the vehicle until it stops in front of the pedestrian, the vehicle will be too close to the pedestrian when it stops, as shown in FIG. 3(a).

[0022] Therefore, in the calculation process of FIG. 2, the braking force required to stop the vehicle at the travel locus distance L is calculated as the required braking force Fx, as shown in FIG. 3(b). However, the required braking force Fx is generated and the current lateral force Fy is not generated. Ｒ If the required braking force Fx is maintained, the resultant force of both forces will go outside the circle of the friction circle model, as shown in Figure 4(b). The circle of the friction circle model represents the maximum friction force that can be generated by the tire, so braking force and lateral force that go outside this circle cannot be generated simultaneously. The maximum friction force is given by μmg, which is the coefficient of friction between the tire and road surface μ, the vehicle mass m, and the gravitational acceleration g. Since the required braking force Fx cannot be reduced, the achievable tire lateral force Fy is calculated as the achievable lateral force Fy according to the following three equations, as shown in Figure 4(c), while maintaining the required braking force Fx. The road friction coefficient μ can be detected, for example, by determining whether the tires lock when full braking is applied. During cornering, the region in which the tire slip angle and cornering force have a linear relationship changes depending on the road friction coefficient μ, so the road friction coefficient μ can also be detected from this linear region.

[0023] The turning radius of the vehicle calculated from this achievable lateral force Fy according to the above formula (1) is the vehicle turning restriction radius r in the calculation process of FIG. 2. As is clear from formula (1), the achievable lateral force Fy is ＲTherefore, the vehicle turning radius r corresponding to the achievable lateral force Fy is smaller than the current turning radius r Ｒ As a result, when the vehicle achieves this vehicle turning limit radius r, as shown by the solid line in FIG. 3(c), the current turning radius r shown by the dashed line in the same figure is Ｒ However, the current turning radius r Ｒ If the vehicle continues to travel at this radius, the required braking force Fx cannot be obtained and the vehicle will get too close to the pedestrian, which is an obstacle ahead. However, if the vehicle turning restriction radius is r, as shown by the solid line in Figure 5, the vehicle can be stopped within the travel locus distance L up to the pedestrian.

[0024] On the other hand, the vehicle turning radius r is the current turning radius r Ｒ If the turning radius r is larger than r, the vehicle will move toward the outside of the driving lane as mentioned above, and therefore if the vehicle turning restriction radius r becomes too large, there is a risk that the vehicle will deviate from the driving lane (current driving path). In this case, if there is no obstacle on the outside of the turning lane of the driving lane (current driving path), the vehicle will not come into contact with anything even if it deviates from the driving lane (current driving path). However, if there is an obstacle on the outside of the turning lane of the driving lane (current driving path), the vehicle may come into contact with the obstacle on the outside of the turning lane if it deviates from the driving lane (current driving path). If a vehicle is turning along a lane, the turning radius at which the vehicle deviates from the driving lane (current driving path) is determined according to the driving lane (also depending on the width of the lane). Therefore, the turning radius at which the vehicle deviates from the driving lane (current driving path) is defined as the maximum allowable turning radius r ｍａｘ For example, the vehicle turning restriction radius r obtained from the high-precision map data 11 and calculated is the maximum allowable turning radius r ｍａｘ If the vehicle turning radius r exceeds the maximum allowable turning radius r ｍａｘ This prevents the vehicle from leaving its lane until it comes to a stop.

[0025] 6 shows the results of a simulation in which braking was performed while cornering on a road surface with a low friction coefficient, i.e., a low μ road surface, using the vehicle driving assistance system of this embodiment. The two dashed arcs in the figure are lane markers indicating both ends of the driving lane in the width direction, the solid arc in the figure shows the driving lane according to the embodiment, i.e., the case where braking was performed by changing the turning driving trajectory, and the two-dot chain arc in the figure shows the driving lane according to the above-mentioned Patent Document 1, i.e., the case where braking was performed without changing the turning driving trajectory. As an example of the simulation, the following is performed: driving speed v = 40 km / h, vehicle mass m = 1500 kg, road surface friction coefficient μ = 0.25, radius of curvature (current turning radius) r at the center of the driving lane Ｒ = 60 m, vehicle turning radius r = 70 m, and lane width 3.7 m. The required braking force (the calculated braking force is the achievable braking force) Fx for the two turning radii was calculated using the above formulas 1 to 3, and the distance (traveling trajectory distance) L from the current vehicle position shown in the figure to the stopping position at the tip of the arrow was calculated. As a result, the current turning radius r Ｒ The distance L traveled to a stop when the turning radius r was 60 m was L = 45.9 m, whereas the distance L traveled to a stop when the turning radius r was 70 m was L = 36.1 m, meaning that the braking distance was shortened (reduced) by 21.3%. Also, as shown in the figure, the position of the distance L traveled to a stop when the turning radius r was 70 m was within the driving lane.

[0026] Although the vehicle cruise assist method and device according to the embodiment have been described above, the present invention is not limited to the configurations described in the above embodiment, and various modifications are possible within the scope of the gist of the present invention. For example, in the above embodiment, the running speed v in equation 1 is set to the current speed, i.e., the braking start speed, but once braking starts, the running speed v decreases over time, so the running speed v may be dynamically changed to follow this.

[0027] In the above example, the vehicle turning restriction radius r calculated according to the achievable lateral force Fy is equal to the maximum allowable turning radius r. ｍａｘ If the vehicle turning radius r is smaller than the maximum allowable turning radius r ｍａｘ Therefore, for example, the vehicle turning radius r can be increased to the maximum allowable turning radius rｍａｘ In other words, if the achievable lateral force Fy is intentionally reduced, the required braking force Fx can be increased (recalculated) accordingly, and in this way, the travel path distance L required for braking can be further shortened (reduced).

[0028] In this way, the vehicle driving assistance system of this embodiment calculates the required braking force Fx required for the vehicle to stop just before the position where it will come into contact with the obstacle ahead, based on the travel path distance from the current position of the vehicle to the position where it will come into contact with the obstacle ahead and the travel speed of the vehicle, and calculates the current lateral force (required lateral force) Fy required for the vehicle to travel along the travel path. Ｒ The required braking force Fx and the current lateral force Fy are calculated based on the vehicle's tires. Ｒ If it is determined that the current lateral force Fy and the current lateral force Fy cannot occur simultaneously, Ｒ By setting a corrected driving trajectory in which the vehicle travels with a lateral force equal to or less than the smaller achievable lateral force Fy, and braking and / or steering the vehicle based on this corrected driving trajectory and the required braking force, it is possible to avoid contact with an obstacle ahead.

[0029] Furthermore, by setting the driving trajectory as a turning trajectory, i.e., by setting a corrected driving trajectory during turning, it becomes possible for the vehicle to stop without getting too close to an obstacle ahead. Also, by setting the obstacle ahead as a pedestrian, bicycle, or motorcycle that has jumped into the lane ahead in the driving direction, it becomes possible for the vehicle to stop without getting too close to an obstacle ahead that cannot be predicted, particularly in autonomous driving.

[0030] In addition, the current lateral force Fy Ｒ By restricting the smaller lateral force to a turning radius that does not deviate from the lane the vehicle is traveling in, it is possible to avoid contact with other obstacles due to departure from the lane.In addition, objects around the vehicle are detected, and if no objects are detected, or if the vehicle deviates from the lane in which it is traveling but does not come into contact with surrounding objects, the restriction of lateral force based on the turning radius is released.This allows the vehicle to stop reliably without getting too close to obstacles ahead.

[0031] In addition, the current lateral force FyＲ If a turning radius larger than the turning radius when the vehicle turns at the allowable turning radius is allowed, the braking force that the vehicle can achieve is recalculated from the lateral force generated on the tire at that allowable turning radius and the friction circle model. This makes it possible to stop the vehicle more reliably without getting too close to an obstacle ahead.

[0032] 1F...front wheels, 1R...rear wheels, 2...brake device, 3...electric booster, 4...hydraulic pressure control device, 5...hydraulic pressure controller, 6...electric steering actuator, 7...steering controller, 8...automatic driving controller, 9...positioning device, 10...surroundings recognition device, 11...high-precision map data, 12...processor, 13...storage device

Claims

1. In a vehicle driving support method that plans a driving trajectory and a driving speed of a vehicle, predicts a possibility of contact between the vehicle and an obstacle when the obstacle is detected ahead in the driving direction, and brakes and / or steers the vehicle to avoid contact when it is predicted that there is a possibility of contact, a required braking force necessary for the vehicle to stop before a position of contact with the obstacle is calculated based on a distance on the driving trajectory from a current position of the vehicle to the position of contact with the obstacle and the driving speed of the vehicle, a required lateral force necessary for the vehicle to travel along the driving trajectory is calculated, it is determined whether the required braking force and the required lateral force can be generated simultaneously by tires of the vehicle, and when it is determined that they cannot be generated simultaneously, a corrected driving trajectory along which the vehicle travels is set so as to be a lateral force smaller than the required lateral force, and the vehicle is braked and / or steered based on the required braking force and the corrected driving trajectory to avoid the contact.

2. The vehicle driving support method according to claim 1, wherein the driving trajectory is a turning driving trajectory.

3. The vehicle driving support method according to claim 1, wherein the obstacle is a pedestrian, a bicycle, or a motorcycle that has jumped out into a lane ahead in the driving direction.

4. The vehicle driving support method according to claim 1, wherein the lateral force smaller than the required lateral force is restricted by a turning radius within a range where the vehicle does not deviate from the lane in which the vehicle is traveling.

5. The vehicle driving support method according to claim 4, wherein an object around the vehicle is detected, and when the object is not detected, or when the vehicle does not contact the surrounding object even if the vehicle deviates from the lane in which the vehicle is traveling, the restriction of the lateral force by the turning radius is released.

6. The vehicle driving support method according to claim 1, wherein when a turning radius larger than a turning radius when the vehicle turns with the required lateral force is allowed, a braking force achievable by the vehicle is recalculated from a lateral force generated in the tire and a friction circle model at the allowed turning radius.

7. In a vehicle driving support device that plans a driving trajectory and driving speed of a vehicle, predicts a possibility of contact between the vehicle and an obstacle when detecting the obstacle in front of the driving direction, and brakes and / or steers the vehicle to avoid contact when it is predicted that contact may occur, based on the distance on the driving trajectory from the current position of the vehicle to the position of contact with the obstacle and the driving speed of the vehicle, calculates a required braking force necessary for the vehicle to stop before the position of contact with the obstacle, calculates a required lateral force necessary for the vehicle to travel along the driving trajectory, determines whether the required braking force and the required lateral force can be generated simultaneously by the tires of the vehicle, and when it is determined that they cannot be generated simultaneously, sets a corrected driving trajectory along which the vehicle travels so as to be a lateral force smaller than the required lateral force, and includes a controller that brakes and / or steers the vehicle based on the required braking force and the corrected driving trajectory to avoid the contact.

Images