Patent Publication Number: US-2022227395-A1

Title: Vehicle Control System and Vehicle Control Method

Description:
TECHNICAL FIELD 
     The present invention relates to a vehicle control system that estimates a state of an object by using information on the object detected by different types of sensors. 
     BACKGROUND ART 
     Background art of the present technical field includes the following prior art. PTL 1 (JP 2017-91029 A) discloses an object detection device as follows. A relative position/speed calculation unit calculates a relative position and a relative speed of a target object based on a signal from a radio wave transmission and reception unit. A prediction unit predicts the relative position and the relative speed on a track of the target object, which has been previously calculated, from this track by using outputs of an acceleration sensor and a yaw rate sensor. A correlation unit determines whether or not the predicted relative position and relative speed are correlated with the relative position and the relative speed of the target object, which are calculated this time. When the predicted relative position and relative speed are correlated with the calculated relative position and the relative speed, the track is updated by the relative position and the relative speed of the target object, which are calculated this time. When the predicted relative position and relative speed are not correlated with the calculated relative position and the relative speed, a track update unit stores the relative position and the relative speed of the target object, which are calculated this time, in a track storage unit (see Abstract). 
     CITATION LIST 
     Patent Literature 
     PTL 1: JP 2017-91029 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     In the technique disclosed in PTL 1, the track is updated in accordance with whether or not the relative position/relative speed of the target object have a correlation, but it is not assumed that the sensor is undetected during turning of the own vehicle. In this case, if the relative position of the target is estimated by interpolation, there is a possibility that the relative position is estimated to be a wrong position. 
     Solution to Problem 
     A representative example of the invention disclosed in this application is as follows. That is, a vehicle control system includes an integration unit that estimates information on a position and a speed of a target existing in an external field and errors of the position and the speed of the target, based on information from a movement sensor that acquires movement information including a vehicle speed and a yaw rate of an own vehicle, and information from an external field sensor that acquires information on the external field of the own vehicle. The integration unit uses not the information from the external field sensor, but the vehicle speed and the yaw rate acquired by the own vehicle movement sensor, to predict a position and a speed of the target and errors of the position and the speed of the target at a second time after a first time, from a position and a speed of the target and errors of the position and the speed at the first time. 
     Advantageous Effects of Invention 
     According to one aspect of the present invention, it is possible to improve accuracy of the position and the speed of a target and errors of the position and the speed. Objects, configurations, and effects other than those described above will be clarified by the descriptions of the following embodiments. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a configuration diagram illustrating a vehicle control system according to an embodiment of the present invention. 
         FIG. 2  is a flowchart illustrating an entirety of integration processing in the present embodiment. 
         FIG. 3  is a flowchart of a prediction update process in Step S 2 . 
         FIG. 4  is a diagram illustrating a process in each step. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An embodiment will be described below with reference to the drawings. 
       FIG. 1  is a configuration diagram illustrating a vehicle control system according to an embodiment of the present invention. 
     The vehicle control system in the present embodiment includes an own-vehicle movement recognition sensor D 001 , an external-field recognition sensor group D 002 , a positioning system D 003 , a map unit D 004 , an input communication network D 005 , a sensor recognition integration device D 006 , an autonomous-driving plan determination device D 007 , and an actuator group D 008 . The own-vehicle movement recognition sensor D 001  includes a gyro sensor, a wheel speed sensor, a steering angle sensor, an acceleration sensor, and the like mounted on the vehicle, and measures a yaw rate, a wheel speed, a steering angle, an acceleration, and the like representing the movement of the own vehicle. The external-field recognition sensor group D 002  detects a vehicle, a person, a white line of a road, a sign, and the like outside the own vehicle, and recognize information on the vehicle, the person, the white line, the sign, or the like. A position, a speed, and an object type of an object such as a vehicle or a person are recognized. The shape of the white line of the road including the position is recognized. For the expression, the position and the content of a sign are recognized. As the external-field recognition sensor group D 002 , sensors such as a radar, a camera, and a sonar are used. The configuration and number of sensors are not particularly limited. The positioning system D 003  measures the position of the own vehicle. As an example of the positioning system D 003 , there is a satellite positioning system. The map unit D 004  selects and outputs map information around the own vehicle. The input communication network D 005  acquires information from various information acquisition devices, and transmits the information to the sensor recognition integration device D 006 . As the input communication network D 005 , the controller area network (CAN), Ethernet, wireless communication, and the like are used. The CAN is a network generally used in an in-vehicle system. The sensor recognition integration device D 006  acquires own vehicle movement information, sensor object information, sensor road information, positioning information, and map information from the input communication network D 005 . Then, the sensor recognition integration device D 006  integrates the pieces of information as own vehicle surrounding information, and outputs the own vehicle surrounding information to the autonomous-driving plan determination device D 007 . The autonomous-driving plan determination device D 007  receives the information from the input communication network D 005  and the own-vehicle surrounding information from the sensor recognition integration device D 006 . The autonomous-driving plan determination device plans and determines how to move the own vehicle, and outputs command information to the actuator group D 008 . The actuator group D 008  operates the actuators in accordance with the command information. 
     The sensor recognition integration device D 006  in the present embodiment includes an information storage unit D 009 , a sensor object information integration unit D 010 , and an own-vehicle surrounding information integration unit D 011 . The information storage unit D 009  stores information (for example, sensor data measured by the external-field recognition sensor group D 002 ) from the input communication network D 005  and provides the information for the sensor object information integration unit D 010  and the own-vehicle surrounding information integration unit D 011 . The sensor object information integration unit D 010  acquires the sensor object information from the information storage unit D 009  and integrates the information of the same object, which is detected by a plurality of sensors, as the same information. Then, the sensor object information integration unit outputs the integration result to the own-vehicle surrounding information integration unit D 011 , as integration object information. The own-vehicle surrounding information integration unit D 011  acquires the integration object information, and the own vehicle movement information, the sensor road information, the positioning information, and the map information from the information storage unit D 009 . Then, the own-vehicle surrounding information integration unit D 011  integrates the acquired information as own-vehicle surrounding information, and outputs the own-vehicle surrounding information to the autonomous-driving plan determination device D 007 . 
     The sensor recognition integration device D 006  is configured by a computer (microcomputer) including an arithmetic operation device, a memory, and an input/output device. 
     The arithmetic operation device includes a processor and executes a program stored in the memory. A portion of the processing performed by the arithmetic operation device executing the program may be executed by another arithmetic operation device (for example, hardware such as a field programmable gate array (FPGA) and an application specific integrated circuit (ASIC)). 
     The memory includes a ROM and a RAM which are non-volatile storage elements. The ROM stores an invariable program (for example, BIOS) and the like. The RAM includes a high-speed and volatile storage element such as a dynamic random access memory (DRAM) and a non-volatile storage element such as a static random access memory (SRAM). The RAM stores a program executed by the arithmetic operation device and data used when the program is executed. The program executed by the arithmetic operation device is stored in a non-volatile storage element being a non-transitory storage medium of the sensor recognition integration device D 006 . 
     The input/output device is an interface that transmits processing contents by the sensor recognition integration device D 006  to the outside or receives data from the outside, in accordance with a predetermined protocol. 
       FIG. 2  is a flowchart illustrating an entirety of integration processing in the present embodiment. 
     The information storage unit D 009  stores sensor data. The sensor data is information of an object (target) recognized by various sensors (radar, camera, sonar, and the like) of the external-field recognition sensor group D 002 , and includes data of a relative position, a relative speed, and a relative position/speed of the recognized object in addition to data of a distance and a direction to the object. The relative position/speed can be represented by a range (for example, a Gaussian distribution type error ellipse) in which the object exists at a predetermined probability at a predetermined time. The Gaussian distribution type error ellipse can be represented by a covariance matrix shown in the following expression, and may be represented in another format. For example, as another form, the existence range of the object may be represented by general distribution other than the Gaussian distribution, which is estimated using the particle filter. 
     The covariance matrix shown in the following expression includes an element indicating a correlation between positions, an element indicating a correlation between speeds, and an element indicating a correlation between positions and speeds. 
     
       
         
           
             
               
                 
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     The memory of the sensor object information integration unit D 010  stores tracking data indicating a trajectory of an object recognized by the various sensors of the external-field recognition sensor group D 002 . 
     In the integration processing, first, the sensor object information integration unit D 010  estimates an error of sensor data (S 1 ). This error is determined by the type of sensor, the position of an object recognized within a recognition range (for example, if the distance to the object is long, the error is large, and the object recognized at the center of the recognition range has a small error), and an external environment (brightness of the external field, visibility, rainfall, snowfall, temperature, and the like). 
     The sensor object information integration unit D 010  updates prediction data of the tracking data (S 2 ). For example, assuming that the object represented by the tracking data performs a uniform linear motion from the previously recognized point without changing the moving direction and the speed, the position of the object at the next time is predicted, and the tracking data is updated. 
     Then, the sensor object information integration unit D 010  executes a grouping process of integrating data representing one object among the predicted position using the tracking data and the observed position using the sensor data (S 3 ). For example, an overlap between the error range of the predicted position using the tracking data and the error range of the observed position using the sensor data is determined, and the predicted position and the observed position where the error ranges overlap each other are grouped as data representing the same object. 
     Then, the sensor object information integration unit D 010  integrates the observation results by using the data determined as the group representing the same object (S 4 ). For example, a weighted average of the predicted positions and the observed positions grouped as the data representing the same object is calculated in consideration of errors of the predicted positions and the observed positions, and an integrated position of the object is calculated. 
     Then, the integrated position is output as a fusion result, and the tracking data is further updated (S 5 ). 
       FIG. 3  is a flowchart of the prediction update process in Step S 2  of  FIG. 2 .  FIG. 4  is a diagram illustrating a process in each step. In  FIG. 4 , the speed is represented by an arrow, the position is represented by a position on  FIG. 4 , and the position/relative speed is represented by an error ellipse. 
     First, the sensor object information integration unit D 010  acquires a first relative speed Vr_t1_t1, a first relative position X_t1_t1, and a first relative position/relative speed Pr_t1_t1 of an object around a vehicle at a predetermined time t1 (S 21 ). The relative speed, the relative position, and the relative position/relative speed are generally represented in a following coordinate system (also referred to as a relative coordinate system) based on a vehicle center position of the own vehicle, but may be represented in a coordinate system based on the position of the sensor that has measured the sensor data. 
     Then, the sensor object information integration unit D 010  converts the relative speed data in the following coordinate system into absolute speed data in a stationary coordinate system. For example, the sensor object information integration unit D 010  uses the first relative position X_t1_t1 to convert the acquired first relative speed Vr_t1_t1 and first relative position/relative speed Pr_t1_t1 in the following coordinate system into a first absolute speed Va_t1_t1 and a first relative position/absolute speed Pa_t1_t1 in the stationary coordinate system (S 22 ). 
     Then, the sensor object information integration unit D 010  obtains the position at time t2 from the position at time t1. For example, with the position O_t1_t1 of the vehicle as the origin, the sensor object information integration unit D 010  converts the first absolute speed Va_t1_t1, the first relative position X_t1_t1, and the first relative position/absolute speed Pa_t1_t1 at the time t1 into the second absolute speed Va_t2_t1, the second relative position X_t2_t1, and the second relative position/absolute speed Pa_t2_t1 at the time t2 (S 23 ). 
     Then, the sensor object information integration unit D 010  updates the origin position of the coordinate system from the time t1 to the time t2, that is, from the coordinate system at the time t1 to the coordinate system at the time t2. For example, the sensor object information integration unit D 010  updates the second relative position X_t2_t1, the second absolute speed Va_t2_t1, and the second relative position/absolute speed Pa_t2_t1 of the object with the position O_t1_t1 of the vehicle at the time t1 as the origin, to the second relative position X_t2_t2, the second absolute speed Va_t2_t2, and the second relative position/absolute speed Pa_t2_t2 of the object with the position O_t2_t1 of the vehicle at the time t2 as the origin (S 24 ). 
     In the conversion from the origin position O_t1_t1 at the time t1 to the origin position O_t2_t1 at the time t2, the measurement values (that is, the turning operation) of the vehicle speed and the yaw rate of the own vehicle are used. 
     Since the measured values of the vehicle speed and the yaw rate include errors, the error range indicated by the second relative position/absolute speed Pa_t2_t2 may be increased in consideration of the error of the vehicle speed and the error of the yaw rate. 
     Then, the sensor object information integration unit D 010  converts the absolute speed data in the stationary coordinate system into relative speed data in the following coordinate system. For example, the sensor object information integration unit D 010  uses the second relative position X_t2_2 to convert the second absolute speed Va_t2_2 and the second relative position/absolute speed Pa_t2_2 in the stationary coordinate system into the second relative speed Vr_t2_2 and the second relative position/relative speed Pr_t2_2 in the following coordinate system in the updated coordinate system (S 25 ). 
     As described above, according to the embodiment of the present invention, the relative position of the object at the time t1 is converted into the relative position of the object at the time t2 in a state where the relative speed of the object is converted into the absolute speed while the position information remains as the relative position. Then, the absolute speed of the object is converted into the relative speed. That is, since the relative position in the following coordinate system at the time t2 is converted from the relative position in the following coordinate system at the time t1 in the state of being converted into the absolute speed, it is possible to improve the accuracy of the position and the speed of the target and the errors thereof without using the information from the external-field recognition sensor group D 002 . In particular, since the turning operation of the own vehicle, which is calculated from the measurement result of the yaw rate is added to the calculation result, it is possible to accurately calculate the relative position/relative speed (error range) even when the own vehicle is turning. Therefore, it is possible to improve the grouping performance of the sensor data of the target and to improve the determination performance of an operation plan. 
     In addition, since the position and the speed and the errors thereof at the second time are predicted in consideration of the error of the vehicle speed and the error of the yaw rate of the own vehicle, it is possible to more accurately calculate the relative position/relative speed (error range). 
     In addition, since the error is represented by a covariance matrix according to the Gaussian distribution, it is possible to calculate the relative position/relative speed (error range). 
     The present invention is not limited to the above-described embodiment, and includes various modifications and equivalent configurations within the spirit of the appended claims. For example, the above examples are described in detail in order to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to a case including all the described configurations. In addition, a portion of the configuration of one example may be replaced with the configuration of another example. Further, the configuration of one example may be added to the configuration of another example. 
     Regarding some components in the examples, other components may be added, deleted, and replaced. 
     In addition, some or all of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by, for example, designing with an integrated circuit, or may be realized by software by a processor interpreting and executing a program for realizing each function. 
     Information such as a program, a table, and a file, that realizes each function can be stored in a memory, a storage device such as a hard disk and a solid state drive (SSD), or a recording medium such as an IC card, an SD card, and a DVD. 
     Control lines and information lines considered necessary for the descriptions are illustrated, and not all the control lines and the information lines in mounting are necessarily shown. In practice, it may be considered that almost all components are connected to each other. 
     REFERENCE SIGNS LIST 
     
         
         D 001  own-vehicle movement recognition sensor 
         D 002  external-field recognition sensor group 
         D 003  positioning system 
         D 004  map unit 
         D 005  input communication network 
         D 006  sensor recognition integration device 
         D 007  autonomous-driving plan determination device 
         D 008  actuator group 
         D 009  information storage unit 
         D 010  sensor object information integration unit 
         D 011  own-vehicle surrounding information integration unit