JP6237256B2 - Vehicle speed control device - Google Patents

Description

  The present invention relates to a vehicle speed control device that controls the speed of a vehicle.

  As this type of device, the road and position on which the vehicle is traveling are estimated by GPS, and the allowable approach speed for the forward curve is calculated using the point data displayed on the road map of the navigation device. A vehicle speed control system that outputs an alarm or performs deceleration control so that an overspeed state (a state in which an allowable approach speed is exceeded) is not known is known (Patent Document 1).

Japanese Patent No. 3092803

A conventional vehicle speed control system controls traveling by turning acceleration considering the motion limit of the vehicle.
However, in the conventional vehicle speed control system, the steering angular velocity increases depending on the road shape and the position of the obstacle, and the vehicle may not be able to travel smoothly.

  The problem to be solved by the present invention is to make a vehicle run smoothly regardless of the road shape or the position of an obstacle.

  The present invention generates a target trajectory having a curvature of a target trajectory that the host vehicle is predicted to travel from road shape information and obstacle information, and a curvature change rate with respect to a moving distance to each point on the target trajectory. The upper limit value of the steering angular velocity allowed for the curvature and the curvature change rate of the vehicle is set, and the control speed of the host vehicle is calculated so that the steering angular velocity calculated from the speed of the host vehicle and the curvature change rate is less than or equal to the upper limit value of the steering angular velocity. The above-described problems are solved by providing a vehicle speed control device that executes control for causing the host vehicle to travel at a control speed or lower.

  According to the present invention, since the vehicle speed is controlled so that the state where the steering angular velocity does not exceed the upper limit value is maintained, the vehicle can be smoothly driven regardless of the road shape or the position and shape of the obstacle.

1 is a first diagram illustrating an overview of a driving support system 1 according to the present embodiment. It is FIG. 2 which shows the outline | summary of the driving assistance system 1 which concerns on this embodiment. It is a block block diagram of the driving assistance system 1 provided with the vehicle speed control apparatus 100 which concerns on this embodiment. It is a functional lineblock diagram of vehicle speed control device 100 concerning this embodiment. It is a flowchart which shows the control procedure of the vehicle speed control knowledge process of this embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a case where the vehicle speed control device according to the present invention is applied to a driving support system that supports driving of a vehicle will be described as an example. The vehicle speed in this embodiment includes the speed of the vehicle. Further, the vehicle speed in the present embodiment includes the acceleration of the vehicle.

  FIG. 1A and FIG. 1B are diagrams showing an outline of a driving support system 1 for a vehicle, and FIG. 2 is a block configuration diagram of the driving support system 1 including a vehicle speed control device 100 according to the present embodiment. As shown in FIGS. 1A and 1B, the driving support system 1 of this embodiment is mounted on a vehicle.

  As shown in FIG. 1A, the driving support system 1 includes a camera 20, a camera controller 21, and a control unit CU. The control unit CU includes the control device 10 and the vehicle controller 50 of the vehicle speed control device 100 shown in FIG.

  The camera 20 captures surrounding images including the front of the vehicle. The region including the front of the vehicle includes a region at a predetermined angle on the left and right with respect to the traveling direction of the vehicle. The camera controller 21 has an image processing function for processing a captured image of the camera 20. The camera controller 21 has a function of acquiring road shape information related to the shape of the road on which the host vehicle is predicted to travel based on the captured image of the camera 20. The camera controller 21 has a function of detecting information related to obstacles around the host vehicle such as a preceding other vehicle traveling in front of the host vehicle.

  The camera 20 of the present embodiment is provided at a substantially central position in the vehicle width direction in front of the vehicle. In the present embodiment, it is installed in a fixed portion such as an upper part of the front window in the vehicle interior or an inner mirror stay in the vehicle interior. The camera 20 is a camera using an image sensor such as a CCD, and captures an image of the traveling direction of the vehicle V. The camera 20 is attached to the vehicle with a lower pitch angle along the direction of gravity. The pitch angle can be appropriately set according to the height of the vehicle and the performance of the camera 20. The camera 20 of this embodiment images the road surface and the road side several meters to several tens of meters ahead of the vehicle. In the present embodiment, it is preferable to use a wide-angle camera 20. The camera 20 outputs the captured image data to an image processing device 21 described later.

  The camera 20 of this embodiment includes an image processing device 21. The image processing device 21 detects a road shape from a captured image of a road (a road ahead of the vehicle) on which the vehicle will travel. The road shape detection method is not particularly limited. For example, as described in Japanese Patent Application Laid-Open No. 11-102499, a white line in the vicinity of the host vehicle is detected by processing such as binarization of the image data of the front camera 25. The relative lateral displacement Y (x) of the vehicle with respect to the travel lane in front of the detected white line is calculated. Information on the road shape based on the white line is output to the control device 10 of the vehicle speed control device 100. The calculation method of the relative lateral displacement Y (x) is not particularly limited, but in this example, multiple points (points) are set in the range of x = 0 [m] to 30 [m], and the number of the set points Only the relative lateral displacement Y (x) of the vehicle with respect to the traveling lane in front of the vehicle is calculated. The relative lateral displacement Y (x) of the vehicle is output to the control device 10 of the vehicle speed control device 100.

  Further, the image processing apparatus 21 according to the present embodiment detects obstacle information related to the presence, position, shape, and the like of an obstacle from a captured image of a road (a road ahead of the vehicle) on which the vehicle will travel. The obstacle detection method is not particularly limited, and edge information is extracted from the captured image, the edge information is evaluated by a method such as pattern matching, and the presence / absence of an obstacle corresponding to the edge information is detected. The image processing device 21 detects an object existing in a region where the host vehicle travels as an obstacle, such as another vehicle in front (around) the host vehicle, a two-wheeled vehicle, a pedestrian, and a road shoulder installation.

  The image processing apparatus 21 sends road shape position information, obstacle position information, or these two pieces of position information to the control apparatus 10 described later. The image processing device 21 may calculate the position information of the extension of the lane in which the host vehicle travels, that is, the target locus predicted to travel the vehicle, from the position information of the road shape and send it to the control device 10. . The image processing device 21 considers the presence of an obstacle, calculates position information of a target trajectory that the vehicle is predicted to travel from the position information of the road shape and the position information of the obstacle, and sends it to the control device 10. It may be sent out. In this example, a configuration example in which the camera 20 of the in-vehicle device 200 includes the image processing device 21 will be described. However, the image processing device 21 may be provided on the vehicle speed control device 100 side.

  FIG. 1B shows a configuration of the driving support system 1 of the present embodiment. In FIG. 1B, 1FL is the left front wheel of the vehicle, 1FR is the right front wheel of the vehicle, 1RL is the left rear wheel of the vehicle, and 1RR is the right rear wheel of the vehicle. The travel support system 1 of this embodiment includes a rack 2, a pinion 3, a steering wheel 4, and a steering shaft 5. The travel support system 1 of the embodiment further includes a steering actuator 16 (EPS or steering torque generating means), a vehicle speed sensor 41, a yaw rate sensor 42, and a steering angle sensor 43.

  Although not particularly limited, a general rack and pinion type steering mechanism is disposed on the front wheels 1FL and 1FR of the vehicle of the present embodiment shown in FIG. 1B. The steering mechanism includes a rack 2 connected to the steering shafts (tie rods) of the front wheels 1FL and 1FR, a pinion 3 meshing with the rack 2, and a steering shaft 5 that rotates the pinion 3 with a steering torque applied to the steering wheel 4. It has. A steering actuator 16 for automatically steering the front wheels 1FL and 1FR is disposed at an upper position of the pinion 3 on the steering shaft 5.

  As shown in FIG. 2, the travel support system 1 of the present embodiment includes a vehicle speed control device 100 and an in-vehicle device 200. In the present embodiment, the vehicle speed control device 100 and the in-vehicle device 200 are connected by a CAN (Controller Area Network) or other in-vehicle LAN in order to exchange information with each other. In the present embodiment, the control device 10 of the vehicle speed control device 100 is integrally configured as a control unit CU together with the vehicle controller 50 of the vehicle. Of course, the control device 10 of the vehicle speed control device 100 and the vehicle controller 50 may be configured as separate units.

  The vehicle speed control device 100 according to the present embodiment calculates a vehicle speed according to the road on which the vehicle is traveling, and executes vehicle speed control of the host vehicle. The driving support system 1 of the present embodiment executes part or all of acceleration / deceleration operation (vehicle speed control operation) and steering operation of the host vehicle, or outputs information necessary for driving the host vehicle to Assist driving.

  The in-vehicle device 200 includes a camera 20, an output device 30, a sensor 40, a vehicle controller 50, a drive device 60, a steering device 70, a travel support device 80, and a navigation device 90. Hereinafter, each device will be described.

  The display 31 and the speaker 32 as the output device 30 of the present embodiment are installed around a dashboard that can be visually recognized by the driver of the vehicle. Information for supporting driving is presented to the driver as necessary.

  The sensor 40 of this embodiment includes a vehicle speed sensor 41, a yaw rate sensor 42, a rudder angle sensor 43, an acceleration sensor 44, and an attitude sensor 45. The vehicle speed sensor 41 is attached to the output side or each wheel of an automatic transmission (not shown), and the vehicle speed detects the moving speed of the vehicle by measuring the number of rotations on the output side of the transmission and the number of rotations of the wheels. The vehicle speed V detected by the vehicle speed sensor 41 is also output to the control unit CU (vehicle controller 50, control device 10). The yaw rate sensor 42 has a yaw angular velocity detection function for detecting the yaw angular velocity generated in the vehicle, and the detected yaw angular velocity γ is also output to the control unit CU (the vehicle controller 50, the control device 10). The steering angle sensor 43 amplifies the rotational displacement of the steering shaft 5 directly or by a gear mechanism or the like, and then detects it as a steering angle detection signal by an angle detection mechanism such as a rotary encoder or a potentiometer. The steering angle sensor 43 of the present embodiment detects the steering angle θ from the rotation angle of the steering shaft 5 and outputs it to the control unit CU (vehicle controller 50, control device 10). The acceleration sensor 44 detects the acceleration of the vehicle and outputs it to the control unit CU (vehicle controller 50, control device 10). The attitude sensor 45 detects an attitude including the traveling direction of the host vehicle. The specific configuration and function of each sensor 40 are not particularly limited, and a sensor known at the time of filing can be used as appropriate.

  The vehicle controller 50 is an ECU (Electronic Control Unit) that controls the operation of the entire vehicle. The vehicle controller 50 acquires detection signals from various sensors 40 mounted on the vehicle. The acquired signal is used for vehicle speed control, and is sent to the driving support device 80 and the vehicle speed control device 100.

  The drive device 60 is a drive mechanism of the vehicle V, and executes acceleration / deceleration control of the vehicle based on input signals from the driver's accelerator operation and brake operation, and control signals acquired from the vehicle controller 50 or the travel support device 80. Thereby, acceleration / deceleration control of the vehicle can be automatically performed.

  The steering control device 70 includes a steering actuator. The steering actuator includes a motor and the like attached to the column shaft of the steering. The vehicle is driven based on an input signal obtained by a driver's steering operation and a control signal acquired from the vehicle controller 50 or the travel support device 80.

  The driving support device 80 uses the detected road shape and the lane marker model stored in the map information 92 of the navigation device 90 so that the host vehicle travels while maintaining the center position of the lane or the host vehicle is in the lane. The steering device 70 is controlled so as to travel while maintaining the lateral position set with respect to the vehicle. The driving support device 80 calculates a steering control amount based on information on the vehicle speed, the steering angle, and the current of the steering actuator acquired from the various sensors 51 of the vehicle controller 50, and sends a current command to the steering actuator. Control is performed so that the vehicle travels in the target lateral position.

  The navigation device 90 includes a GPS (Global Positioning System) 91 that detects a current position, and map information 92 that associates point information, road information, facility information, and the like with position information.

  Next, the vehicle speed control device 100 will be described. As shown in FIG. 2, the vehicle speed control device 100 of this embodiment includes a control device 10. The vehicle speed control device 100 according to the present embodiment calculates the control vehicle speed of the host vehicle and controls the host vehicle to run at a control vehicle speed or less.

  The control device 10 of the vehicle speed control device 100 of the present embodiment is configured by a discretized digital system such as a microcomputer (not shown), and the vehicle speed control device 10 calculates the control speed of the own vehicle and controls the own vehicle. Run below. The control device 10 of the vehicle speed control device 100 according to the present embodiment executes a vehicle speed control by executing a ROM (Read Only Memory) 12 storing a program for controlling the vehicle speed of the host vehicle and a program stored in the ROM. The computer includes a CPU (Central Processing Unit) 11 as an operation circuit that functions as the device 100 and a RAM (Random Access Memory) 13 that functions as an accessible storage device.

  FIG. 3 is a functional block diagram of the control device 10 included in the vehicle speed control device 100 according to the present embodiment. The control device 10 of this embodiment includes a road shape information acquisition function, an obstacle information acquisition function, a target locus generation function, a steering angular velocity upper limit value setting function, a yaw angular velocity upper limit value setting function, and a lateral acceleration upper limit value setting function. And a control vehicle speed calculation function and a vehicle speed control function. The control vehicle speed calculation function has a vehicle speed upper limit calculation function and an acceleration upper limit calculation function. The control device 10 of this embodiment includes a yaw angular acceleration upper limit value setting function or a lateral jerk upper limit value setting function. The control device 10 of the present embodiment is a computer that executes each function by cooperation of software for realizing the above function and the above-described hardware.

  Hereinafter, each function of the vehicle speed control apparatus 100 according to the present embodiment will be described.

  First, the road shape information acquisition function of the control device 10 of the present embodiment will be described. The control device 10 of the present embodiment acquires road shape information related to the shape of the road predicted to travel by the host vehicle. The control device 10 of the present embodiment specifies the current position of the host vehicle using the current position of the host vehicle detected by the GPS 91 of the navigation device 90 and the traveling direction of the host vehicle detected by the attitude sensor 45 of the host vehicle. . The control device 10 is present in front of the vehicle from the identified current position, and acquires the shape of the road from which the host vehicle is predicted to travel. The map information 92 stores the shape of the road associated with the point information. The control device 10 acquires, from the map information 92, road shape information of a road on which the host vehicle is predicted to travel based on the current position of the host vehicle. Moreover, the control apparatus 10 of this embodiment may identify a road area | region from the picked-up image of the camera 20 installed in the own vehicle, and may acquire the road shape information of a road from the extension shape of the road area | region. As a technique for detecting the road shape based on the captured image, a technique known at the time of filing can be appropriately used. The acquired road shape information is used for target locus generation processing.

  The obstacle information acquisition function of the control device 10 of this embodiment will be described. The control device 10 of the present embodiment acquires obstacle information around the host vehicle. The obstacle information includes an object on the road where the host vehicle is predicted to travel. Objects on the road include road signs, parked vehicles, parked vehicles, and preceding vehicles. The control device 10 of the present embodiment extracts image feature points from the captured image of the camera 20 and evaluates the presence of the object and the type of the object based on the extracted feature points. As a technique for detecting an obstacle based on a captured image, a technique known at the time of filing can be appropriately used. The acquired obstacle information is used for target locus generation processing.

  A target locus generation function of the control device 10 of the present embodiment will be described. The control device 10 according to the present embodiment calculates the curvature of the target trajectory that the host vehicle is predicted to travel from the acquired road shape information and obstacle information, and the curvature change rate with respect to the travel distance to each point on the target trajectory. . In the present embodiment, the target locus is a movement locus of the vehicle when traveling while avoiding obstacles existing on the road scheduled to travel. The control device 10 recognizes the shape of the road on which the host vehicle will travel from the road shape information. When there are obstacles on the road, it is inappropriate to set the target locus according to the road shape. The control device 10 according to the present embodiment generates a target trajectory for traveling while avoiding obstacles on the road shape and the road. This target trajectory is defined by the curvature of the trajectory predicted to travel by the host vehicle and the curvature change rate.

  The steering angular velocity upper limit setting function of the control device 10 of the present embodiment will be described. The control device 10 of the present embodiment sets an upper limit value of the steering angular velocity that is allowed in the calculated curvature of the target locus and the curvature change rate. In the present embodiment, the steering angular speed at which the driver can travel with confidence when the vehicle is actually traveled is set as the upper limit value of the steering angular speed. In the present embodiment, the steering angular velocity at which the steering control follow-up delay can be ignored when the vehicle is actually traveled is set as the upper limit value of the steering angular velocity. The upper limit value of the steering angular velocity is set in advance by an experiment involving actual traveling (including simulation).

  The control device 10 according to the present embodiment is configured so that the target steering angle (hereinafter referred to as “target steering angle”) is calculated in consideration of the vehicle speed so that the target locus of the calculated curvature of the target locus and the target locus of the curvature change rate can travel along the locus. "), And a steering angular velocity (hereinafter also referred to as" target steering angular velocity ") is calculated. The target steering angle can be obtained from the curvature of the target locus and the vehicle speed. The target steering angular velocity can be obtained from the curvature change rate of the target locus and the vehicle speed. Although it is an example, the target steering angle is calculated using Equation 4 described later. In this case, it is preferable that the curvature of the target trajectory is continuous so that the discontinuous target steering angle is not calculated. That the locus | trajectory to drive | work is not continuous is a road where a road curvature (or turning radius) transfers to the curve of 100R (curvature radius 100m) from a straight line, and further to a straight road, for example.

  The control device 10 of the present embodiment sets the upper limit value of the steering angular velocity according to the target steering angle obtained from the curvature / curvature change rate of the target change rate. By the way, even if the road has the same curvature, the target steering angle differs if the vehicle speed is different. In order for the steering angle / steering angular velocity to change smoothly (with a large amount of change kept below a predetermined amount), the curvature change rate is calculated with a non-infinite value, and the vehicle speed increases as the curvature change rate increases. This can be realized by driving at a low level.

The yaw angular velocity upper limit setting function of the control device 10 of the present embodiment will be described. The control device 10 of the present embodiment sets an upper limit value of the yaw angular velocity that is allowed when the host vehicle travels on the target locus. In the present embodiment, the yaw angular velocity (change in vehicle behavior) that allows the driver to travel with confidence when the vehicle is actually traveling is set as the upper limit value of the yaw angular velocity. The upper limit value of the yaw angular velocity is set in advance by experiments involving actual running (including simulation). In this experiment, the driver's sense of security is investigated in actual driving with varying vehicle speed and yaw angular velocity. The sense of security may be a subjective evaluation of the driver or an objective evaluation such as a driver's biological reaction.

  In addition, a yaw angular acceleration upper limit setting function may be further provided. The control device 10 of the present embodiment sets an upper limit value of the yaw angular acceleration that is allowed when the host vehicle travels on the target locus. In the present embodiment, the yaw angular acceleration (change in vehicle behavior) that allows the driver to travel with confidence when the vehicle is actually traveled is set as the upper limit value of the yaw angular acceleration. The upper limit value of the yaw angular acceleration is set in advance by experiments involving actual running (including simulation). In this experiment, the driver's sense of security is investigated in actual driving with varying vehicle speed and yaw angular velocity. The sense of security may be a subjective evaluation of the driver or an objective evaluation such as a driver's biological reaction.

  The lateral acceleration upper limit setting function of the control device 10 of the present embodiment will be described. The control device 10 of the present embodiment sets an upper limit value of the lateral acceleration that is allowed when the host vehicle travels on the target locus. In the present embodiment, the lateral acceleration (vehicle behavior change) that allows the driver to travel with confidence when the vehicle is actually traveled is set as the upper limit value of the lateral acceleration. The upper limit value of the lateral acceleration is set in advance by an experiment involving actual running (including simulation). In this experiment, the driver's sense of security (subjectivity) is investigated in actual driving with varying vehicle speed and lateral acceleration.

  In addition, a lateral jerk upper limit setting function may be further provided. The control device 10 according to the present embodiment sets an upper limit value of the lateral jerk allowed when the host vehicle travels on the target locus. Lateral jerk is the rate of change of lateral acceleration per unit time. Lateral jerk is also called jerk or jerk. In the present embodiment, the lateral jerk (change in vehicle behavior) that allows the driver to travel with confidence when the vehicle is actually traveled is set as the upper limit value of the lateral jerk. The upper limit value of the lateral jerk is set in advance by experiments involving actual running (including simulation). In this experiment, the driver's sense of security (subjectivity) is investigated during actual driving with varying vehicle speed and lateral jerk.

  A control speed calculation function of the control device 10 of the vehicle speed control device 100 of the present embodiment will be described. The control speed calculation function of the control device 10 of the present embodiment has a vehicle speed upper limit calculation function and an acceleration upper limit calculation function.

  First, the vehicle speed upper limit calculation function will be described. The control device 10 of the present embodiment calculates the control speed of the host vehicle such that the steering angular speed calculated from the speed of the host vehicle and the curvature change rate is equal to or less than the steering angular speed upper limit value.

  The control device 10 of the present embodiment includes an upper limit value Sθmax of the steering angular velocity, a curvature ρ of the target locus, a curvature change rate κ = dρ / dx of the target locus, a vehicle speed V, a wheel base l, and a stability factor A. Based on the above, the control speed V of the host vehicle is calculated such that the steering angular velocity when traveling along the target locus is equal to or less than the steering angular velocity upper limit value Sθmax. A specific method for calculating the control speed V will be described later together with the procedure. The calculated control speed is used for speed control processing in automatic driving or driving support of the host vehicle.

When the speed of the vehicle is equal to or higher than a predetermined value, the control device 10 according to the present embodiment is configured so that the host vehicle does not move even if the steering angular speed calculated from the speed of the host vehicle and the curvature change rate is equal to or lower than the steering angular speed upper limit value. The control speed of the host vehicle is calculated such that the yaw angular velocity when traveling on the target locus is equal to or lower than the upper limit value of the yaw angular velocity, or the lateral acceleration when the host vehicle travels on the target locus is equal to or lower than the upper limit value of the lateral acceleration.
In the control device 10 of the present embodiment, the host vehicle travels along the target locus based on the yaw angular velocity upper limit value γmax, the curvature change rate κ = dρ / dx of the target locus, the curvature ρ of the target locus, and the vehicle speed V. The control speed V of the host vehicle is calculated such that the yaw angular velocity at the time of running is equal to or lower than the upper limit value of the yaw angular velocity or the lateral acceleration when the host vehicle travels on the target locus is equal to or lower than the upper limit value of the lateral acceleration.

  The speed threshold value (predetermined value) used for determining whether or not the vehicle speed is equal to or higher than a predetermined value in the present embodiment is a region where the sensitivity of the yaw angular velocity / yaw angular acceleration to the steering angular velocity increases as the vehicle speed increases. It defines beforehand according to. Since this characteristic varies depending on the vehicle type and vehicle specification, it is preferable to define a speed threshold (predetermined value) based on the actual driving test result.

  In general, the sensitivity of the yaw angular velocity with respect to the steering angular velocity (a characteristic that generates a large yaw angular velocity with a small steering angular velocity) and the sensitivity of the yaw angular acceleration (a large yaw angular acceleration with a small steering angular velocity) vary depending on the vehicle type and the destination of the vehicle Characteristic), the vehicle speed increases linearly to about 0 to 50 km / h, and is saturated at a vehicle speed of about 70 km / h. On the other hand, the sensitivity characteristics of the yaw angular velocity and the yaw angular acceleration tend to increase as the vehicle speed increases. That is, in a region where the vehicle speed is high, there is a characteristic that a large yaw angular velocity / yaw angular acceleration is generated with a small steering angular velocity. In the region where the sensitivity of the yaw angular velocity / yaw angular acceleration to the steering angular velocity increases as the vehicle speed increases, the vehicle speed control device 100 of the present embodiment converts the yaw angular velocity / yaw angular acceleration generated at the upper limit value of the steering angular velocity into the yaw angular velocity.・ Set the upper limit of yaw angular acceleration to a smaller value.

  Thereby, when the vehicle speed is high, the control vehicle speed that preferentially suppresses the yaw angular velocity / yaw angular acceleration can be calculated. That is, the vehicle speed control device 100 according to the present embodiment determines whether to give priority to vehicle speed control based on the yaw angular velocity / yaw angular acceleration or lateral acceleration different from the steering angular velocity based on the vehicle speed, or to prioritize vehicle speed control based on the steering angular velocity. You can choose. In other words, not only the uniform vehicle speed control that predicts the steering angular velocity and suppresses the vehicle speed, but also directly evaluates the yaw angular velocity, yaw angular acceleration, and lateral acceleration, which are quantities that directly indicate changes in vehicle behavior. The vehicle speed can be suppressed in consideration of changes in vehicle behavior.

Next, the acceleration upper limit calculation function will be described.
When the target trajectory calculation function determines that the vehicle shifts from the turning state to the straight traveling state based on the calculated curvature change rate, the control device 10 of the vehicle speed control device 100 of the present embodiment determines the speed of the host vehicle. Then, the control acceleration of the host vehicle is calculated such that the steering angular velocity calculated from the curvature change rate is equal to or less than the steering angular velocity upper limit value.

  The control device 10 according to the present embodiment determines whether or not the vehicle shifts from the turning state to the straight traveling state based on the curvature and / or the curvature change rate of the target locus. Specifically, the reference pattern of the curvature and / or curvature change rate of the trajectory in which the vehicle transitions from the turning state to the straight traveling state is compared with the curvature and / or curvature change rate pattern of the target trajectory on which the vehicle travels. If the characteristic points are common as a result of the comparison, it is determined that the vehicle is in a state of shifting from a turning state to a straight traveling state.

  When the control device 10 of the vehicle speed control device 100 according to the present embodiment determines that the curvature change rate in the calculated target locus is constant, the yaw angular acceleration when the host vehicle travels the target locus is the yaw angle. The control acceleration of the host vehicle is calculated such that the lateral jerk when the host vehicle travels on the target locus is equal to or less than the upper limit value of the acceleration or less than the upper limit value of the lateral jerk.

  The control device 10 according to the present embodiment determines whether or not the curvature change rate in the target locus is constant. When the amount of change in the curvature change rate of the target locus on which the vehicle is traveling is less than a predetermined value, it is determined that the curvature change rate in the target locus is constant.

  The vehicle speed upper limit value and the acceleration upper limit value calculated by the control vehicle speed calculation function are used for vehicle speed control processing. The control device controls the speed of the vehicle using the calculated vehicle speed upper limit value and acceleration upper limit value.

  The speed control function of the control apparatus 10 of this embodiment is demonstrated. The control device 10 according to the present embodiment executes control for causing the host vehicle to travel below the calculated control speed. The control device 10 according to the present embodiment executes control for causing the host vehicle to travel below the calculated control acceleration. The control method of the host vehicle based on the vehicle control speed (predetermined speed) and the vehicle control acceleration (predetermined acceleration) is not particularly limited, and a technique known at the time of filing of the present application can be used as appropriate.

  Next, the procedure of the vehicle speed control process executed by the control unit 10 of the present embodiment will be described based on FIG. This process is executed as a timer interrupt process every 10 msec, for example.

  Due to restrictions on the electronic application format of the Japan Patent Office, there are characters that cannot be used as text data in the body of the specification. For example, with respect to the quantity x, a differential symbol in which a dot symbol “•” is added to the head of a character “x” generally referred to as “x dot”, or two dot symbols “•” on the head of “x”.・ Second-order differential symbols with “” cannot be used in electronic applications with the JPO. For this reason, in the text part of this specification, the symbol “S” is added to the “x dot” as a first-order differential symbol obtained by differentiating the amount x once, and expressed as “SX”, and the amount x is expressed as The symbol “SS” is added to “x two dots” as a second-order differential symbol that has been differentiated twice, and is expressed as “SSX”, and “x three dots” as a third-order differential symbol that is obtained by differentiating the quantity x three times. The symbol “SSS” is attached and expressed as “SSSX”. However, the mathematical formula input by the image data is expressed in such a manner that the original dot symbol is attached to the head of the character.

  As shown in FIG. 4, in step S <b> 1, the control device 10 of the vehicle speed control device 100 of the present embodiment uses the steering angle θ detected by the steering angle sensor 43, the yaw angular velocity γ detected by the yaw rate sensor 42, and the vehicle speed sensor 22. After reading the detected vehicle speed V and the vehicle lateral displacement Y (x) detected by the camera controller 26, the process proceeds to step S2. The control device 10 stores in advance a wheel base l (el), which is the distance between the front and rear wheels, a front-rear wheel cornering power, a center-to-front wheel axis distance from the center of gravity, and a stability factor A defined by the vehicle weight.

  In step S <b> 2, the control device 10 of the present embodiment acquires road shape information related to the shape of the road predicted to travel by the host vehicle. In parallel, the control device 10 of the present embodiment acquires obstacle information around the host vehicle.

In step S _{<b> 3} , the control device 10 of the present embodiment uses the curvature data string {ρ _{x = x 1} , ρ _{x = of the} target trajectory that the host vehicle is predicted to travel from the acquired road shape information and obstacle information around the vehicle. _x2 ,..., ρ _{x = xN} } and a curvature change rate data string {κ _{x = x 1} , κ _{x = x 2} ,..., κ _{x = xN} } with respect to the moving distance to each point on the target locus.
Here, κ can be defined by the following formula 1.

The control device 10 of the present embodiment includes the curvature data sequence {ρ _{x = x1} , ρ _{x = x2} ,..., Ρ _{x = xN} } of the obtained target trajectory and the curvature change rate data sequence {κ _{x = x1} , κ _{x = x2} ,..., κ _{x = xN} } to generate a target trajectory where the vehicle is predicted to travel.

Next, the process proceeds to step S4, and the control device 10 of the present embodiment sets the yaw angular velocity upper limit value γ _MAX and / or the lateral acceleration upper limit value SSy _MAX .

Next, the process proceeds to step S5, where the steering angular velocity upper limit value Sθ _MAX is set. In addition, you may progress to step S5 from step S3. The steering angular velocity upper limit value Sθ _MAX can be obtained using Equation 4 described later.

In parallel with step S4 and step S5, step S11 is executed. In step S11, the control device 10 of the present embodiment sets the yaw angular acceleration upper limit value Sγ _MAX and / or the lateral jerk upper limit value SSSy _MAX . Lateral jerk upper limit SSSy _MAX may be calculated by using the lateral acceleration limit SSSy _MAX obtained in step S4.

  Next, in step S6, a vehicle speed upper limit value is calculated. In the present embodiment, the vehicle speed upper limit value is calculated from the viewpoint of preventing excessive vehicle behavior. The vehicle speed upper limit is an aspect of “control vehicle speed” in the present embodiment. As the control vehicle speed, a value substantially the same as the vehicle speed upper limit value may be used, or a vehicle speed lower than the vehicle speed upper limit value may be used as the control vehicle speed.

A series of processing examples for obtaining the vehicle speed upper limit value as the control vehicle speed will be shown below.
In the present embodiment, the yaw rate γ is defined by Equation 2, for example.

In the present embodiment, the curvature ρ of the trajectory along which the vehicle travels is defined by, for example, Expression 3.

ただし、Ａはスタビリティファクタと呼ばれる車両の運動特性を決定する定数である。 In the present embodiment, the target steering angle θ of the host vehicle when traveling along the locus of curvature ρ can be expressed by, for example, Expression 4.

However, A is a constant which determines the motion characteristic of the vehicle called a stability factor.

Formula 5 shows the basic formula for circular turning.

The control device 10 of the present embodiment uses the basic equation of circular turning shown in Equation 5 to determine the vehicle speed at which the yaw angular velocity is equal to or less than the yaw angular velocity upper limit value γ _max and the lateral acceleration is equal to or less than the lateral acceleration upper limit value SSy _max. An upper limit value V _max is calculated.
Specifically, the control device 10 of the present embodiment calculates the vehicle speed upper limit value V _MAX using, for example, the following formula 6.

Next, the control device 10 according to the present embodiment controls the vehicle speed upper limit value V such that the steering angular velocity Sθ generated when steering control is performed to travel the target locus calculated in step S3 is equal to or less than the steering angular velocity upper limit value Sθ _max. Calculate _max .

The control device 10 according to the present embodiment uses, for example, an equation for the steering angular velocity Sθ generated when steering control is performed based on the curvature data string necessary for traveling along the target locus calculated in step S3. 7 is obtained.

Based on the relationship of the following equation 8, in step S6, the vehicle speed upper limit value V is calculated so that the steering angular velocity Sθ of equation 7 is smaller than the steering angular velocity upper limit value Sθ _max .

That is, although it is an example, the vehicle speed upper limit value V that satisfies the following expression 9 is calculated. That is, the upper limit vehicle speed that satisfies the condition that the steering angular velocity calculated from the curvature of the target locus, the curvature change rate of the target locus, and the speed (vehicle speed) of the host vehicle is smaller than the set steering angular velocity upper limit value is calculated. .

  The plus and minus signs added to the steering angle θ correspond to the steering direction. For example, in the case of + θ, the steering wheel is cut to the left and the vehicle is directed leftward. In the case of −θ, the steering wheel is cut to the right and the vehicle is directed rightward. The curvature change rate is defined in the same way. The direction in which the curvature is larger to the left (the turning radius is smaller) is defined to be positive.

Specifically, assuming SV << 1, the vehicle speed satisfying the following equation 10 using the equation 9 and the curvature change rate data string {κ _{x = x1} , κ _{x = x2} ,..., Κ _{x = xN} }. The upper limit value V = V _max is calculated.

In step S6, the control device 10 of the present embodiment calculates the vehicle speed upper limit value V _max so that the vehicle behavior change indicated by the yaw angular acceleration Sγ is smaller than the yaw angular acceleration upper limit value Sγ _max . As an additional condition, the control device 10 of the present embodiment calculates the vehicle speed upper limit value V _max so that the vehicle behavior change indicated by the vehicle lateral acceleration SSy is smaller than the lateral acceleration upper limit value SSy _max .

The yaw angular acceleration Sγ and the lateral jerk upper limit value SSSy _max are obtained by the following expression 11. A value obtained by differentiating the lateral acceleration SSy once more is the lateral jerk SSSy.

As the yaw angular acceleration upper limit value Sγ _max and the lateral jerk upper limit value SSSy _max , a vehicle speed upper limit value V _max and an acceleration upper limit value S _max that satisfy the following Expression 12 are calculated.
Specifically, assuming SV << 1, the upper limit of vehicle speed satisfying Equation 12 using Equation 12 and the curvature change rate data string {κ _{x = x 1} , κ _{x = x 2} ,..., Κ _{x = xN} }. The value V _max and the acceleration upper limit value S _max are calculated.

The calculation processing of the control vehicle speed of the vehicle in consideration of the yaw angular velocity upper limit value γ _max and the lateral acceleration upper limit value SSy _max may be executed when the vehicle speed is equal to or higher than a predetermined value.

In step S7, the vehicle acceleration upper limit SV _max is calculated such that Equation 9 is smaller than the steering angular velocity upper limit Sθ _max . The following Expression 14 is obtained from Expression 7.

From the relationship of Equation 14, the curvature data string {ρ _{x = x1} , ρ _{x = x2} ,..., Ρ _{x = xN} } of the target locus, and the curvature change rate data string {κ _{x = x1} , The acceleration upper limit SV _max is calculated as in the following equation 15 using κ _{x = x 2} ,..., κ _{x = xN} }. The acceleration calculated from Equation 15 using the steering angular velocity upper limit value is set as the acceleration upper limit value, and traveling control is performed based on the acceleration upper limit value.

Since there is a difference in the expression development depending on the curvature of the turning direction and the direction of change of the curvature, the relationship is obtained for each positive and negative curvature ρ. There are positive and negative conditions for curvature and curvature change rate, respectively. Equation 15 determines the upper limit SV _max of the forward acceleration that keeps the vehicle behavior in the lateral direction as smooth as possible when going toward a straight line in the latter half of the curve.

  The process of step S7, that is, the acceleration control process considering the operation angular velocity may be executed when it is determined from the calculated curvature change rate that the vehicle shifts from the turning state to the straight traveling state.

Further, in step S7, the control device 10 of the present embodiment, vehicle behavior change, such as a yaw angular acceleration and the vehicle lateral jerk, such as smaller than the yaw angular acceleration upper limit value S [gamma] _max and lateral jerk upper limit SSSy vehicle The upper limit of acceleration is calculated. From Expression 12, the acceleration upper limit SV _max satisfies the following Expression 16. The acceleration calculated from the following equation 16 is set as the acceleration upper limit value, and the speed control is performed based on the acceleration upper limit value.

The acceleration upper limit SV satisfying the above equation 16 can be calculated by the following equation 17.

  The process of step S7, that is, the acceleration control process considering the yaw angular acceleration and the lateral jerk may be executed when it is determined that the calculated curvature change rate is constant.

Finally, in step S8, the control device 10 according to the present embodiment generates a target vehicle speed train from the current time using the speed upper limit value V _max calculated in step 6 and the acceleration upper limit value SV _max calculated in step 7. To do.

  In step S8, when the low speed section is calculated ahead, the control device 10 of the present embodiment gradually increases with a predetermined deceleration set value from before the low speed section in order to prevent sudden braking. A control command including the target vehicle speed train is generated so as to decelerate the vehicle speed. The control device 10 according to the present embodiment may directly control the driving of the vehicle by sending a control command related to speed to the driving device 60. The control device 10 according to the present embodiment may send a control command related to speed to the driving support device 80 and cause the driving support device 80 to control driving of the vehicle. A specific method of vehicle speed control of the vehicle is not particularly limited, and a method known at the time of filing is appropriately used.

  In addition, the control device 10 of the present embodiment, when a section with a large target vehicle speed upper limit value is calculated ahead, the target vehicle speed so as to gradually accelerate at a predetermined acceleration setting value from the front so as not to suddenly accelerate. Generate a control instruction that contains a sequence.

Furthermore, the control device 10 according to the present embodiment compares the acceleration upper limit SV _max calculated in the previous step with a predetermined acceleration setting value α set in advance by the vehicle speed control device 100 during acceleration, and accelerates the acceleration. When the upper limit SV _max is smaller than the acceleration set value α, a control command for accelerating at the acceleration upper limit SV _max is generated. On the other hand, when the acceleration upper limit SV _max is equal to or higher than the acceleration set value α, the control device 10 of the present embodiment generates a control command for accelerating at the acceleration set value α.

  Since the vehicle speed control device 100 of the present embodiment is configured and operates as described above, the following effects can be obtained.

[1] Since the vehicle speed control device 100 of the present embodiment controls the vehicle speed of the host vehicle so that the steering angular velocity does not exceed the upper limit value regardless of the road shape and the position and shape of the obstacle, It is possible to realize traveling control with a small follow-up error with respect to the traveling locus of the host vehicle.
In the vehicle speed control device 100 of this embodiment, a vehicle speed upper limit value is calculated from the curvature and the curvature change rate so that the steering angular velocity is equal to or lower than the steering angular velocity upper limit value, and the vehicle travels at a control speed derived from the vehicle speed upper limit value. To control.
Since the vehicle speed control device 100 of the present embodiment can reduce the steering angle, it is possible to reduce the tracking error to the target locus. In a scene where a large steering angular velocity is required, it is necessary to realize a large steering angle change in a short time. However, there are cases where the output timing of the steering angle amount necessary for traveling according to the target trajectory deviates from an appropriate timing due to disturbance such as road surface reaction force or delay in the control system. If the actual steering angle deviates from the steering angle target value, the vehicle cannot be driven according to the target locus.
On the other hand, if the steering angular velocity is kept small, the update amount per cycle of the control processing of the control target value of the steering angle may be small. For this reason, the actual steering angle is less likely to be delayed from the steering angle target value, and a necessary steering angle amount can be output at an appropriate timing. That is, the vehicle can be driven in a state where no tracking error occurs with respect to the target locus.
According to the vehicle speed control device 100 of the present embodiment, even in a scene where a large steering angular velocity is generated due to the shape of the road on which the traveling is scheduled and the position and shape of the obstacle to be avoided, the vehicle cannot smoothly travel. It can be controlled to run.
For example, a scene where the curvature changes suddenly at the joint between a straight line and a curve, that is, when entering a curved road, especially when entering a small curved road, a straight road and a circular road are connected. When driving on a road that is configured in this way, even if the vehicle is driven at a vehicle speed that can easily turn the turning radius (or curvature) of the road, it is necessary to increase the steering angular speed at the point where the curve and the straight line change, and smooth I ca n’t drive.
Since the vehicle speed control device 100 of the present embodiment controls the vehicle speed of the host vehicle so that the state in which the steering angular velocity does not exceed the upper limit value is maintained, the steering angle is not increased pinpoint even in such a situation. The vehicle can run smoothly. The vehicle speed control according to the present embodiment is also applied to roads where the switching between a curve and a straight line is set at a short distance, such as a driving scene at an entrance / exit of an intersection, a driving scene when making a U-turn, and a driving scene on a winding road. The apparatus 100 can run the vehicle smoothly.

  [2] The vehicle speed control device 100 according to the present embodiment allows the steering angular velocity calculated from the speed of the host vehicle and the curvature change rate to be equal to or lower than the steering angular velocity upper limit value when the vehicle speed is equal to or higher than a predetermined value. The control speed of the host vehicle is such that the yaw angular velocity when the host vehicle travels on the target locus is less than or equal to the upper limit value of the yaw angular velocity, or the lateral acceleration when the host vehicle travels on the target track is less than or equal to the upper limit value of the lateral acceleration. calculate. For this reason, even when the vehicle speed is relatively high, a sudden change in the behavior of the vehicle can be suppressed, so that the vehicle can travel smoothly and a comfortable driving control can be realized.

[3] The vehicle speed control device 100 according to the present embodiment is calculated from the speed of the host vehicle and the rate of curvature change when it is determined that the vehicle shifts from the turning state to the straight state based on the calculated rate of curvature change. The control acceleration of the host vehicle is calculated such that the steering angular velocity becomes equal to or less than the steering angular velocity upper limit value. For this reason, when shifting from a turning state to a straight traveling state, such as when escaping from a curve, maximum acceleration is possible with the movement of the steering wheel being suppressed.
When the vehicle transitions from a turning state to a straight traveling state, the vehicle speed that is the vehicle motion limit tends to be calculated higher, so an acceleration state that matches the driver's sense according to the road shape may not be obtained. There is a problem that there is. On the other hand, the vehicle speed control device 100 according to the present embodiment controls the acceleration state to the maximum while the movement of the steering wheel is suppressed when the vehicle transitions from the turning state to the straight traveling state. The vehicle speed can be controlled with matching acceleration conditions.
Even when accelerating when moving from a road with a small radius of curvature to a straight road, the tracking error due to the delay in returning the steering wheel can be suppressed, so that the vehicle can be moved along the target track. And accelerate.

  [4] When the vehicle speed control device 100 according to this embodiment determines that the calculated rate of curvature change in the target trajectory is constant, the acceleration when the host vehicle travels the target trajectory is the upper limit of the yaw angular acceleration. The control acceleration of the host vehicle is calculated so that the lateral jerk when the vehicle travels the target locus is equal to or less than the upper limit value of the lateral jerk. According to the vehicle speed control device 100 of the present embodiment, the acceleration is controlled while maintaining the state in which the values of the yaw angular acceleration and the lateral jerk are suppressed even when the road curvature is in a constant turning state. Rapid changes in vehicle behavior can be suppressed. As a result, the vehicle can travel smoothly and travel control with good ride comfort can be realized.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  That is, in the present specification, the present invention will be described by taking the vehicle travel support system 1 including the vehicle speed control device 100 and the in-vehicle device 200 as an example, but the present invention is not limited to this.

  In this specification, the vehicle speed control device 100 including the control device 10 will be described as an example of one aspect of the vehicle speed control device according to the present invention, but the present invention is not limited to this.

  In the present specification, a vehicle speed according to the present invention, comprising road shape information acquisition means, obstacle information acquisition means, target locus generation means, steering angular velocity upper limit setting means, control vehicle speed calculation means, and vehicle speed control means. As an example of a control device, a control device that executes a road shape information acquisition function, an obstacle information acquisition function, a target locus generation function, a steering angular speed upper limit setting function, a control vehicle speed calculation function means, and a vehicle speed control function Although the vehicle speed control apparatus 100 provided with 10 is demonstrated as an example, it is not limited to this.

  In this specification, as an example of a vehicle speed control device according to the present invention that includes a yaw angular velocity upper limit value setting unit or a lateral acceleration upper limit value setting unit, a control device that executes a yaw angular velocity upper limit value setting function or a lateral acceleration upper limit value setting function. Although the vehicle speed control apparatus 100 provided with 10 is demonstrated as an example, it is not limited to this.

  In the present specification, a yaw angular acceleration upper limit setting function or a lateral jerk upper limit setting function is executed as an example of a vehicle speed control device according to the present invention that includes a yaw angular acceleration upper limit setting means or a lateral jerk upper limit setting means. Although the vehicle speed control apparatus 100 provided with the control apparatus 10 is demonstrated as an example, it is not limited to this.

DESCRIPTION OF SYMBOLS 1 ... Driving assistance system 100 ... Vehicle speed control apparatus 10 ... Control apparatus 11 ... CPU
12 ... ROM
13 ... RAM
DESCRIPTION OF SYMBOLS 200 ... In-vehicle device 20 ... Camera 30 ... Output device 40 ... Sensor 41 ... Vehicle speed sensor 42 ... Yaw rate sensor 43 ... Steering angle sensor 44 ... Acceleration sensor 45 ... Attitude sensor 31 ... Display 31 ... Speaker 50 ... Vehicle controller 60 ... Drive device 70 ... Steering device 80 ... Driving support device 90 ... Navigation device 91 ... GPS
92 ... Map information, road information

Claims (4)

Road shape information acquisition means for acquiring road shape information related to the shape of the road on which the host vehicle is predicted to travel;
Obstacle information acquisition means for acquiring obstacle information around the host vehicle;
Calculate the curvature of the target trajectory that the host vehicle is predicted to travel from the acquired road shape information and the obstacle information, and the curvature change rate with respect to the travel distance to each point on the target trajectory, and the curvature Target trajectory generating means for generating a target trajectory having the curvature change rate;
Steering angular velocity upper limit value setting means for setting an upper limit value of the steering angular velocity allowed in the calculated curvature of the target locus and the curvature change rate;
A control speed calculation means for calculating a control speed of the host vehicle in which a steering angular speed calculated from the speed of the host vehicle and the curvature change rate is equal to or lower than the steering angular speed upper limit value;
Speed control means for causing the host vehicle to travel below the control speed;
A vehicle speed control device comprising: A yaw angular velocity upper limit value setting means for setting an upper limit value of a yaw angular velocity allowed when the host vehicle travels on the target track, or an upper limit value of lateral acceleration permitted when the host vehicle travels on the target track. A lateral acceleration upper limit setting means for setting
When the speed of the vehicle is equal to or higher than a predetermined value, the control speed calculation means may calculate the control angular speed even if a steering angular speed calculated from the speed of the host vehicle and the curvature change rate is equal to or lower than the steering angular speed upper limit value. The yaw angular velocity when the host vehicle travels the target locus is equal to or lower than the upper limit value of the yaw angular velocity, or the lateral acceleration when the host vehicle travels the target track is equal to or lower than the upper limit value of the lateral acceleration. The vehicle speed control apparatus according to claim 1, wherein a control speed is calculated. When the target trajectory calculating means determines that the vehicle shifts from the turning state to the straight traveling state based on the calculated curvature change rate, the control speed calculating means determines the speed of the host vehicle and the curvature. Calculating a control acceleration of the host vehicle in which a steering angular velocity calculated from a change rate is equal to or lower than the steering angular velocity upper limit value;
The vehicle speed control device according to claim 1, wherein the speed control means causes the host vehicle to travel below the control acceleration. Yaw angular acceleration upper limit setting means for setting an upper limit value of yaw angular acceleration allowed when the host vehicle travels on the target locus, or lateral jerk allowed when the host vehicle travels on the target track. A lateral jerk upper limit setting means for setting an upper limit;
When the target trajectory calculating means determines that the calculated curvature change rate is constant, the control speed calculating means determines that the yaw angular acceleration when the host vehicle travels the target trajectory is the yaw angular acceleration. The control acceleration of the host vehicle is calculated so that the lateral jerk when the host vehicle travels the target locus is equal to or less than the upper limit value of the angular acceleration, or less than the upper limit value of the lateral jerk,
The vehicle speed control device according to claim 1, wherein the speed control means causes the host vehicle to travel below the control acceleration.

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