JP4941240B2 - Traveling locus generation method and traveling locus generation device - Google Patents

Description

  The present invention relates to a travel locus generation method and a travel locus generation apparatus.

2. Description of the Related Art Conventionally, a method for generating a travel locus of a vehicle has been adopted, for example, in an apparatus that provides a predicted travel locus to a driver through a display or the like (see, for example, Patent Document 1). The device of Patent Document 1 is a device that derives a travel locus based on the road shape and the traveling speed of the host vehicle, and projects the derived travel locus on a windshield or the like to provide to the driver.
JP 2005-228139 A

  However, in the conventional travel locus generation device, since the travel locus that reaches or passes at the fastest speed is derived based on the road shape and the travel speed of the host vehicle, the grip force of the tire is near the limit of the friction circle. Tend to be.

  That is, in the conventional travel locus generation device, if the constraint condition with a constant usage rate (for example, 90%) of the friction circle is set and priority is given to the time to reach or pass, the friction is generated in any scene. Since only a travel locus that uniformly uses a circle can be generated, it is difficult to generate a travel locus while ensuring a margin for a friction circle, for example, in accordance with the relationship with other vehicles and road surface conditions. Therefore, when something unexpected occurs due to a relationship with another vehicle or the like, the grip force of the tire may exceed the friction circle.

  Therefore, the present invention has been made to solve such a technical problem, and in a state where the constraint condition is satisfied, a traveling locus in which a margin of a friction circle is appropriately secured in consideration of traveling safety. It is an object to provide a travel locus generation method and a travel locus generation apparatus that can be derived.

  That is, the travel locus generation method according to the present invention includes a convergence calculation step for deriving a travel locus by performing a convergence operation so as to achieve a constraint condition based on a road boundary line, and friction so that the safety of traveling is not ensured. An evaluation function generation step that generates an evaluation function that is weighted so as to increase the weight of a term that evaluates the yen usage rate, and a traveling that derives a travel locus by performing a convergence operation on the evaluation function in a state where the constraint condition is achieved A trajectory deriving step.

  According to this invention, the constraint condition based on the road boundary line is converged and a weighted evaluation function is generated so that the weight of the term for evaluating the friction circle usage rate is increased so that the driving safety is not ensured. Then, the generated evaluation function is subjected to a convergence calculation in a state where the constraint condition is achieved, and a traveling locus is derived. As a result, in a scene where the safety of traveling is ensured, a travel locus with less margin of the friction circle can be used, and in a scene where safety of traveling is not ensured, a travel locus with a margin in the friction circle can be used. Therefore, it is possible to derive a traveling locus in which a friction circle is appropriately secured according to the scene. Here, the fact that the safety of driving is not guaranteed is a case where the safety is reduced compared to normal driving, for example, when the distance between other vehicles is short or the road surface friction coefficient decreases due to the weather etc. This is the case. The friction circle usage rate indicates the ratio between the limit value of the friction circle or the set maximum value of the friction circle and the grip force determined from the acceleration force, braking force, and lateral force applied to the current tire.

  In the evaluation function generation step, it is preferable to generate an evaluation function including a term for evaluating the passing time and / or a term for evaluating low fuel consumption driving. In a state where the passage time or / and the fuel consumption are reflected, it is possible to derive a travel locus in which a margin of a friction circle is appropriately secured in consideration of travel safety.

  Furthermore, in the evaluation function generation step, it is preferable to increase the weighting of the term for evaluating the friction circle usage rate as the distance to the surrounding vehicle or the inter-vehicle time decreases. By configuring in this way, the margin of the friction circle can be changed according to the distance to the surrounding vehicle or the time between the vehicles, so a travel locus that appropriately secures the margin of the friction circle in relation to the surrounding vehicle can be obtained. Can be derived.

  Further, the travel locus generating apparatus according to the present invention includes a convergence calculation unit that derives a travel locus by performing a convergence operation so as to achieve a constraint condition based on a road boundary line, and the safety of traveling is not ensured. An evaluation function generator that generates an evaluation function that is weighted so as to increase the weight of a term that evaluates the friction circle usage rate, and in a state where the constraint condition is achieved, the evaluation function is converged to derive a traveling locus And a travel locus deriving unit.

  Here, it is preferable that the evaluation function generation unit generates an evaluation function including a term for evaluating the passage time and / or a term for evaluating low fuel consumption travel.

  Furthermore, it is preferable that the evaluation function generation unit increases the weighting of the term for evaluating the friction circle usage rate as the distance to the surrounding vehicle or the inter-vehicle time decreases.

  By configuring in this way, the traveling locus generating device can obtain the same effect as the traveling locus generating method described above.

  According to the present invention, it is possible to derive a traveling locus in which a margin of a friction circle is appropriately secured in consideration of traveling safety in a state where the constraint condition is satisfied.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same or an equivalent part, and the overlapping description is abbreviate | omitted.

  The travel locus generation device according to the present embodiment is a device that generates a travel locus of a vehicle, for example, a vehicle equipped with an automatic driving function or a vehicle equipped with a driver support system such as a follow-up operation or a lane keeping operation. It is suitably adopted for

  First, the configuration of the travel locus generation apparatus (travel locus generation unit) according to the present embodiment will be described. FIG. 1 is a block diagram showing a configuration of a vehicle provided with a travel locus generating apparatus according to an embodiment of the present invention.

  A vehicle 5 shown in FIG. 1 is a vehicle having an automatic driving function, and includes a GPS receiver 30, a sensor 31, an operation unit 32, a navigation system 33, an ECU 2, a steering actuator 40, a throttle actuator 41, and a brake actuator 42. ing. Here, the ECU (Electronic Control Unit) is a computer of an automobile device that is electronically controlled, and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input / output interface, and the like. It is configured.

  For example, the GPS receiver 30 has a function of receiving driver position information. Here, the GPS (Global Positioning System) is a measurement system using a satellite and is preferably used for grasping the current position of the host vehicle. The GPS receiver 30 has a function of outputting position information to the ECU 2.

  The sensor 31 has a function of acquiring the traveling environment around the vehicle 5 and the traveling state of the host vehicle. As the sensor 31, for example, a lane recognition sensor or an image sensor for recognizing a lane of a road on which the vehicle 5 travels, an electromagnetic wave sensor or a millimeter wave sensor for detecting an obstacle around the vehicle 5, and a yaw rate of the vehicle 5 are measured. A yaw rate sensor, a wheel speed sensor for measuring the wheel speed of the vehicle 5, or the like is used. The sensor 31 has a function of outputting the acquired information to the ECU 2.

  The operation unit 32 has a function of inputting conditions requested by the driver. As the operation unit 32, for example, an operation panel for inputting a target passage time, a target fuel consumption, or the like is used. The operation unit 32 has a function of outputting the input information to the ECU 2.

  The navigation system 33 mainly has a function of performing route guidance to a destination. In addition, the navigation system 33 has a function of reading shape information and a road surface friction coefficient of a currently running road from a map database, for example, and outputting the road shape information and a road surface friction coefficient to the ECU 2 as a navigation signal. The vehicle 5 may include a database storing at least road shape information and a road surface friction coefficient instead of the navigation system, and may have a function of outputting the road shape information and the road surface friction coefficient stored in the database to the ECU 2. . Moreover, it is good also as a structure which has a function which refers road condition information and a road surface friction coefficient via communication, and outputs the referred road shape information and road surface friction coefficient to ECU2.

  The ECU 2 has a function of generating a friction circle from a road surface friction coefficient, vehicle specification information, and the like, and includes a travel locus generation unit 1, a vehicle motion control unit 27, a steering control unit 28, and an acceleration / deceleration control unit 29. .

  The travel locus generation unit 1 has a function of generating an optimized travel locus of the vehicle 5. In the present embodiment, an example using SCGRA [Sequential Conjugate Gradient Restoration Algorithm] will be described as an example of an optimization method executed by the travel locus generation unit 1. SCGRA is an optimization method that performs a convergence calculation based on the steepest descent method until a constraint condition is satisfied, and generates a travel locus by performing a convergence calculation based on a conjugate gradient method until the evaluation value of the evaluation function is minimized. Here, the constraint condition is an indispensable condition that the travel locus must satisfy, and the evaluation function is for evaluating a condition that is important in traveling.

  The travel trajectory generated by the travel trajectory generation unit 1 is composed of a number of parameters necessary for vehicle travel, such as position, speed pattern, acceleration pattern, yaw angle, and yaw rate. As an example of such a travel locus generation method, in the present embodiment, a description will be given of an example in which a predetermined section is generated in units of blocks, and a travel path in each block is generated in units of meshes that are sections obtained by dividing the travel path. .

  The travel locus generation unit 1 provided in the ECU 2 includes a convergence calculation unit 21, an evaluation function generation unit 22, and a travel locus derivation unit 23.

  The convergence calculation unit 21 has a function of inputting road environment information such as a road boundary line from the navigation system 33 and inputting wheel friction circle limit information generated by the ECU 2 and setting a constraint condition based on the input information. Have. As described above, the constraint condition is set based on, for example, traffic demands such as traveling on a road and demands generated from vehicle performance such as friction circles, acceleration / deceleration limits, and steering limits. In addition, the convergence calculation unit 21 has a function of performing a convergence calculation until the set constraint condition is satisfied using, for example, the steepest descent method, and generating a traveling locus satisfying the constraint condition. Further, the convergence calculation unit 21 has a function of saving the generated travel locus satisfying the constraint condition as a constraint condition achievement state in a memory included in the ECU 2.

  The evaluation function generation unit 22 has a function of generating an evaluation function including a term for evaluating the passage time and the friction circle usage rate, and based on the information input from the sensor 31, the distance from the surrounding vehicle is determined between A function that generates an evaluation function that increases the coefficient of the term that evaluates the friction circle usage rate according to the shortness of the intervehicular time when the minimum value of the obtained intervehicular time is lower than the predetermined value. have. In addition, the evaluation function generation unit 22 has a function of outputting the generated evaluation function to the travel locus deriving unit 23.

  The travel locus deriving unit 23 inputs the constraint condition and the constraint condition achievement state generated by the convergence calculation unit 21 from the memory of the ECU 2, and receives the evaluation function from the evaluation function generation unit 22 to achieve the constraint condition. In this state, the evaluation function is converged by setting the constraint condition achievement state as an initial value, and a traveling locus in which a margin of a friction circle is appropriately secured is generated. Specifically, a convergence calculation is performed based on the conjugate gradient method to generate a travel locus. The travel locus deriving unit 23 has a function of outputting the calculated travel locus to the vehicle motion control unit 27.

  The vehicle motion control unit 27 has a function of calculating steering control information and acceleration / deceleration control information based on the travel locus input from the travel locus deriving unit 23, the surrounding traveling environment from the sensor 31, and the traveling state of the host vehicle. is doing. Further, the vehicle motion control unit 27 has a function of outputting the calculated steering control information to the steering control unit 28 and the calculated acceleration / deceleration control information to the acceleration / deceleration control unit 29.

  The steering control unit 28 has a function of generating a signal for controlling the steering actuator 40 based on the steering control information input from the vehicle motion control unit 27 and outputting the generated control signal to the steering actuator 40. . The steering actuator 40 is a mechanical component that controls the traveling of the vehicle, and is, for example, a steering angle control motor.

  The acceleration / deceleration control unit 29 generates a signal for controlling the throttle actuator 41 and the brake actuator 42 based on the acceleration / deceleration control information input from the vehicle motion control unit 27, and uses the generated control signal as the throttle actuator 41 and the brake actuator. The function to output to 42 is provided. The throttle actuator 41 is a mechanical component that controls traveling of the vehicle, and is, for example, an electronic throttle. The brake actuator 42 has a function of adjusting the brake hydraulic pressure of each wheel in the case of a hydraulic brake, for example.

  Next, the operation of the travel locus generation unit 1 according to this embodiment will be described. FIG. 2 is a flowchart showing the operation of the travel locus generation unit 1 according to this embodiment. FIG. 3 is a schematic diagram for explaining the operation of the travel locus generating unit 1 according to the present embodiment.

  The control process shown in FIG. 2 is repeatedly executed at a predetermined timing after the ignition is turned on, for example.

  When the control process shown in FIG. 2 is started, the travel locus generation unit 1 starts from the travel locus generation process (S10). The process of S10 is a process which the convergence calculation part 21 performs, and calculates the travel locus of a block so that a constraint condition may be satisfied. First, the convergence calculation unit 21 sets a constraint condition that is a constraint condition based on the road boundary line and the friction circle limit of the wheel. For example, the convergence calculation unit 21 inputs road environment information including a road boundary line from the navigation system 33 and inputs information related to the friction circle from the ECU 2 to set a constraint condition. For example, when generating a trajectory that travels from the starting point to the target point (block), the convergence calculation unit 21 inputs the width, slope, curve radius, and the like of the road connecting the starting point and the target point, and Enter the limit value of the friction circle and set the constraint conditions. As a result, a basic constraint condition is set that the vehicle must travel on the road in the block. Further, a basic constraint condition is set that the vehicle must not move so as to be in a state in which the motion cannot be controlled.

  Next, the convergence calculation unit 21 generates the current travel locus so as to satisfy the constraint condition using the travel locus obtained last time (the initial locus in the case of the first convergence calculation). Specifically, for example, based on the correction formula used in the steepest descent method, changes are made to the parameters constituting the previously obtained travel locus (initial locus in the case of the first convergence calculation), and the constraint condition is achieved. A traveling locus close to the traveling locus to be generated is generated. When the process of S10 ends, the process proceeds to a constraint condition determination process (S12).

  The process of S12 is a process which the convergence calculation part 21 performs and determines whether the driving | running | working locus | trajectory produced | generated by the process of S10 satisfies a constraint condition. In the process of S12, when it is determined that the calculated travel locus does not satisfy the constraint condition, the process proceeds to the travel locus generation process again (S10). Thereby, the convergence calculation unit 21 repeatedly performs the convergence calculation shown in S10 and the determination shown in S12 (convergence calculation) until a running locus satisfying the constraint condition can be generated, and generates a traveling locus satisfying the constraint condition (convergence). Calculation step). Note that the processes of S10 and S12 are performed for each mesh obtained by dividing a block by a predetermined distance, for example.

On the other hand, in the process of S12, when it determines with the produced | generated driving | running | working locus | trajectory satisfy | filling constraint conditions, it transfers to an inter-vehicle time acquisition process (S14). The process of S14 is a process which the evaluation function production | generation part 22 performs, and acquires the inter-vehicle time from the inter-vehicle distance to a surrounding vehicle. For example, as shown in FIG. 3, the evaluation function generation unit 22 uses the sensor 31 to acquire the inter-vehicle distances L1, L2 to the front traveling vehicles 4A, 4B and the inter-vehicle distance L3 to the rear traveling vehicle 4C. The inter-vehicle times T _4A , T _4B , and T _4C are acquired based on the inter-vehicle distance and the relative speed. When the process of S14 ends, the process proceeds to an evaluation function generation process (S16).

なお、本実施形態に係る走行軌跡生成部１は、未来の危険性を低減させるためにあらかじめ緊急回避する準備を行うものであるので、実際に緊急回避が必要な場合には、摩擦円に余裕を設ける必要性が無いため、このような場合には、式１に関わらずｋ＝０が設定される。 The process of S16 is a process of generating an evaluation function including a term executed by the evaluation function generation unit 22 and evaluating the friction circle usage rate based on the inter-vehicle time acquired in the process of S14. The evaluation function generation unit 22 sets a friction circle importance coefficient k, which is a coefficient of a term for evaluating the friction circle usage rate, based on the inter-vehicle time acquired in the process of S14. For example, the minimum inter-vehicle time is selected from the acquired inter-vehicle times T _4A , T _4B , T _4C , and if the selected inter-vehicle time is a predetermined value (for example, 1 second) or less, the abnormal behavior of the other vehicle Therefore, the friction circle importance coefficient k is set large. Specifically, the friction circle importance coefficient k is set using the following equation.

Note that the travel locus generation unit 1 according to the present embodiment prepares for emergency avoidance in advance in order to reduce the risk of the future. In such a case, k = 0 is set regardless of Equation 1.

The evaluation function generation unit 22 generates the evaluation function J using the friction circle importance coefficient k calculated using Equation 1. It is assumed that a block, which is a section in which the vehicle 5 travels, is divided into n (n: natural number) meshes, t _{n is} the time for traveling from the departure point to the nth mesh, and the nth mesh is traveling from the departure point. The evaluation function J is expressed by the following equation, where _pn is the usage rate of the friction circle at the time.

  When the process of S16 ends, the process proceeds to a travel locus generation process (S18). In addition, although the term which evaluates passage time is included in the evaluation function shown in Equation 2, the condition for evaluating passage time in Equation 2 takes into account the performance required for each vehicle 5, etc. What is necessary is just to add as needed in each traveling locus generation apparatus. Moreover, it is good also as an evaluation function which changes a passage time and evaluates low fuel consumption driving | running | working, and is good also as an evaluation function including the terms of both evaluation.

  The process of S18 is a process which is performed by the travel locus deriving unit 23 and derives a travel locus using the evaluation function generated in the process of S16. The travel locus deriving unit 23 inputs the constraint condition from the convergence calculation unit 21 and, in a state where the input constraint condition has been achieved, for example, based on a correction formula used in the conjugate gradient method, In this convergence calculation, the travel locus parameter obtained last time is changed so that the evaluation value of the travel locus satisfying the convergence condition calculated in S10 becomes small, and the current travel locus is generated. When the process of S18 ends, the process proceeds to an evaluation condition determination process (S20).

  The process of S20 is a process of determining whether or not the evaluation condition is satisfied by using the travel locus generated by the travel locus deriving unit 23 and generated in the process of S18. Specifically, the travel locus deriving unit 23 calculates an evaluation value from the evaluation function J using the travel locus generated in the process of S18, and satisfies the evaluation condition when the calculated evaluation value is minimized. It is determined that Whether or not the evaluation value has become minimum is determined as the evaluation value being minimum when the evaluation value calculated up to the current process changes, that is, when the differential value of the evaluation value becomes 0 or substantially 0 To do. In the process of S20, when it is determined that the evaluation condition is not satisfied, the process proceeds to the travel locus generation process again (S18). Thereby, the traveling locus deriving unit 23 repeatedly performs the convergence calculation shown in S18 and the determination shown in S20 until the traveling locus satisfying the evaluation condition that gives priority to the margin of the friction circle usage rate can be generated (convergence calculation), and the friction circle Is appropriately secured and a travel locus prepared for abnormal behavior of the other vehicles 4A, 4B, and 4C is generated (travel locus deriving step). When the process of S20 ends, the control process shown in FIG. 2 ends.

  This is the end of the control process shown in FIG. In this way, the travel locus generation unit 1 includes the friction circle in the evaluation function, and changes the weighting of the term for evaluating the friction circle usage rate of the evaluation function according to the inter-vehicle time with other vehicles, The more the safety of traveling is not ensured, the greater the reserve of the friction circle usage rate can be secured and the provision for emergency avoidance can be sufficiently performed.

  As described above, according to the travel locus generation unit 1 according to the present embodiment, the constraint condition based on the friction circle limit and the road boundary line is converged and the inter-vehicle time with the surrounding vehicle is smaller than the predetermined value (the travel The evaluation function J is weighted so as to increase the weight of the friction circle emphasis coefficient k which is a coefficient of the term for evaluating the friction circle usage rate as safety is not guaranteed), and the generated evaluation function J is In a state where the constraint condition is achieved, a running locus is derived by performing a convergence calculation. As a result, when the inter-vehicle time with the surrounding vehicle is larger than the predetermined value, that is, when the safety of traveling is ensured, the traveling locus with a reduced margin of the friction circle is set, and the inter-vehicle time with the surrounding vehicle exceeds the predetermined value. In a small case, that is, in a scene where the safety of traveling is not ensured, a traveling locus with a margin in the friction circle can be obtained. Therefore, when there is sufficient space between the vehicle and the surrounding vehicle, it is possible to generate the fastest travel locus using the friction circle to the limit, and there are narrow surrounding vehicles between the vehicles, and the prediction is based on the relationship with that vehicle. Even if an external situation occurs, use a margin of the friction circle secured in advance to avoid it, and generate a large lateral force, braking force, acceleration force, etc. to deal with unexpected situations Can do.

  In addition, embodiment mentioned above shows an example of the traveling locus generation method or traveling locus generation device which concerns on this invention. The travel trajectory generation method or the travel trajectory generation apparatus according to the present invention is not limited to the travel trajectory generation method or the travel trajectory generation apparatus according to the embodiment, and the embodiment is within a range not changing the gist described in each claim. The travel locus generation method or the travel locus generation apparatus according to the above may be modified or applied to other things.

  For example, in the above embodiment, an example of putting the friction circle limit condition into the constraint condition has been described, but even if it is not included in the constraint condition, the friction circle usage rate is evaluated with the evaluation function. A traveling locus in which a friction circle is appropriately secured according to the scene can be derived.

  Moreover, although the said embodiment demonstrated the case where the vehicle 5 was a vehicle provided with the automatic driving function, it is applicable also to the vehicle and system which coordinated manual driving and automatic driving | operation.

In the above embodiment, the inter-vehicle distance L1, L2, L3, following time _{T 4A,} T _4B, to obtain the _{T 4C} friction circle emphasis coefficient with other vehicles 4A, 4B4C based on the information obtained by the sensor 31 Having described the example of setting the k, and a communication device on the vehicle 5, the vehicle-to-vehicle communication or road-vehicle vehicle distance L1, L2, through the communication such as communication L3, following time _{T 4A, T 4B, T 4C} And the friction circle importance coefficient k may be set.

  In the above embodiment, an example in which a term for evaluating the passage time is included in the evaluation function has been described. However, for example, a term for evaluating low fuel consumption driving, a term for evaluating riding comfort, a term for evaluating safety, and the like are included. In other words, as long as a term for evaluating the friction circle is included in the evaluation function, the term is not limited to other evaluation function terms.

It is a block diagram which shows the structure outline | summary of a vehicle provided with the traveling locus generation part which concerns on 1st Embodiment. It is a flowchart which shows the operation | movement of the traveling locus generation part of FIG. It is a schematic diagram explaining the operation | movement of the traveling locus generation part of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Travel locus | trajectory production | generation part (travel locus production | generation apparatus), 2 ... ECU, 21 ... Convergence calculation part (convergence calculation step), 22 ... Evaluation function production | generation part (evaluation function production | generation step), 23 ... Travel locus deriving part (travel locus) Derivation step).

Claims (6)

A convergence calculation step for deriving a traveling locus by performing a convergence calculation so as to achieve a constraint condition based on a road boundary line;
An evaluation function generation step for generating an evaluation function weighted so as to increase the weight of the term for evaluating the friction circle usage rate so that the safety of traveling is not guaranteed;
In a state where the constraint condition is achieved, a travel locus derivation step for deriving a travel locus by performing a convergence calculation on the evaluation function;
A travel locus generation method comprising:   2. The travel locus generation method according to claim 1, wherein the evaluation function generation step generates an evaluation function including a term for evaluating the passing time and / or a term for evaluating low fuel consumption traveling.   3. The travel locus generation method according to claim 1, wherein the evaluation function generation step increases the weighting of the term for evaluating the friction circle usage rate as the distance to the surrounding vehicle or the inter-vehicle time decreases. A convergence calculation unit for deriving a travel locus by performing a convergence calculation so as to achieve a constraint condition based on a road boundary line;
An evaluation function generation unit that generates an evaluation function weighted so as to increase the weight of a term that evaluates the friction circle usage rate so that the safety of traveling is not guaranteed;
In a state where the constraint condition is achieved, a traveling locus deriving unit that derives a traveling locus by performing a convergence calculation on the evaluation function;
A travel locus generating apparatus comprising:   5. The travel locus generation apparatus according to claim 4, wherein the evaluation function generation unit generates an evaluation function including a term for evaluating a passing time and / or a term for evaluating low fuel consumption traveling.   6. The travel locus generating apparatus according to claim 4, wherein the evaluation function generation unit increases the weight of a term for evaluating the friction circle usage rate as the distance to the surrounding vehicle or the inter-vehicle time decreases.

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