Patent Publication Number: US-2023162596-A1

Title: Message transmission system and method for roadside equipment

Description:
This application claims the benefit of Taiwan application Serial No. 110143862, filed Nov. 24, 2021, the disclosure of which is incorporated by reference herein in its entirety. 
     BACKGROUND 
     Technical Field 
     The disclosure relates in general to a roadside equipment, and more particularly to a message transmission system and a method thereof for a roadside equipment. 
     Description of the Related Art 
     The current broadcast operation method of a road side unit (RSU) is limited by bandwidth. If there are too many object messages, the distance between the object and the intersection can only be used as a basis for selection of messages. In addition, if all object messages are sent by broadcast, RSU cannot accurately provide dangerous object messages, because some object messages (such as vehicles stopped on the roadside, vehicles far away from intersection) are not related to those objects with on-board unit (OBU), and it will result in a waste of resources of wireless transmission bandwidth. 
     SUMMARY 
     The disclosure is directed to a message transmission system and a method thereof for a roadside equipment, which can send out dangerous object messages based on a degree of danger of the object within the available transmission bandwidth, so as to reduce the transmission volume of vehicle-to-road communication. 
     According to one embodiment, a message transmission method for roadside equipment is provided and includes the following steps: receiving information from a plurality of external sensors, entering a road intersection sign phase information and a road map information, performing an object position analysis, a speed analysis, and a sign analysis in object moving direction based on the external sensor information, the road intersection sign phase information, and the road map information, and outputting a classification of dangerous objects in different groups. According to a current transmission bandwidth limitation and the classification of the dangerous objects, a dangerous object message with a higher classification of the dangerous objects is preferentially selected and transmitted within an available transmission bandwidth. 
     According to another embodiment, a message transmission system for a roadside equipment is provided, which includes a dynamic detection device for object at intersection, a sign receiving device, a dangerous object classification module, and a vehicle-to-road communication device. The dynamic detection device for object at intersection is used to receive information from a plurality of external sensors. The sign receiving device is used for inputting a road intersection sign phase information and a road map information. The dangerous object classification module performs an object position analysis, a speed analysis, and a sign analysis in object moving direction based on the external sensor information, the sign phase information of the road intersection, and the road map information, and outputs a classification of dangerous objects in different groups based on the external sensor information, the sign phase information of the road intersection, and the road map information. The vehicle-to-road communication device preferentially selects and transmits a dangerous object message with a higher classification of the dangerous objects within an available transmission bandwidth according to a current transmission bandwidth limitation and the classification of the dangerous objects. 
     The above and other aspects of the disclosure will become better understood with regard to the following detailed description of the embodiment(s). The following description is made with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a schematic diagram showing the operation of components of a message transmission system for a roadside equipment according to an embodiment of the present disclosure; 
         FIG.  1 B  is a schematic diagram of a method of transmitting message for a roadside equipment according to an embodiment of the present disclosure; 
         FIG.  2    is a schematic diagram of an object at an intersection and its position, speed, and moving direction according to an embodiment of the present disclosure; 
         FIG.  3 A  is a schematic diagram of the position analysis of object at the intersection according to an embodiment of the present disclosure; 
         FIG.  3 B  is a schematic diagram of objects at the intersection and the classification of dangerous objects in group D after the position analysis of  FIG.  3 A ; 
         FIG.  3 C  is a schematic diagram of the sign analysis in object moving direction and speed analysis of the objects at the intersection according to an embodiment of the present disclosure; 
         FIG.  3 D  is a schematic diagram of the classification of dangerous objects at the intersection in groups C and D after the sign analysis and speed analysis of  FIG.  3 C ; 
         FIG.  3 E  is a schematic diagram of the analysis of the degree of danger of the objects at the intersection according to an embodiment of the present disclosure; 
         FIG.  3 F  is a schematic diagram of the classification of dangerous objects at the intersection in groups A, B, C, and D after the analysis of the degree of danger of  FIG.  3 E . 
     
    
    
     In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. 
     DETAILED DESCRIPTION 
     Technical solutions for the embodiments of the present application are clearly and thoroughly disclosed with accompanying drawings. Obviously, the embodiments disclosed below are only some rather than all of the embodiments of the present disclosure. All embodiments obtained by anyone ordinarily skilled in the art of the present application according to the disclosed embodiments of the present disclosure are within the scope of protection of the present disclosure if the obtained embodiments are obvious. The same or similar elements will be represented by the same or similar reference signs. 
     Please refer to  FIGS.  1 A and  1 B .  FIG.  1 A  is a schematic diagram of the operation of components of a message transmission system  100  for a roadside equipment according to an embodiment of the present disclosure, and  FIG.  1 B  is a schematic diagram of a message transmission method for a roadside equipment according to an embodiment of the present disclosure. 
     In this embodiment, the message transmission system  100  for a roadside equipment includes a dynamic detection device  110  for object at the intersection, a sign receiving device  120 , a dangerous object classification module  130 , and a vehicle-to-road communication device  140 . The dynamic detection device  110  at the intersection is installed on a side of the road to detect cars, motorcycles, bicycles, or pedestrians (hereinafter referred to as the object  101 ) passing through the intersection. The dynamic detection device  110  at the intersection can include LiDAR modules, laser ranging modules, camera modules, image recognition modules, and computing modules, etc., which can calculate the position, the speed, and the object moving direction of each detected object passing through the intersection in real time, the relative distance between the detected object and the intersection, and the relative distance between the object and the object. 
     In this embodiment, the dynamic detection device  110  at the intersection can cooperate one or more LiDAR modules, laser ranging modules or camera modules to obtain the external sensor information  112  corresponding to the object at the intersection, and obtain different types of external sensor information  112  through sensor fusion  113 , which are aggregated into a cluster of object data  114  at the intersection for the machine to determine. The fused external sensor information  112  includes the position, the speed, the acceleration, the object moving direction and relative distance of the objects, etc. In addition, the fused external sensor information  112  can also include the type of objects (for example, truck, passenger car, bus, motorcycle), the state of the object (stationary, moving, straight moving, turning, decelerating, accelerating, etc.), determine whether the relative distance between the object and the intersection is greater than or less than a preset threshold, and whether the relative distance between the object and the object is greater than or less than a preset threshold, etc. 
     Please refer to  FIG.  2   . Generally, the intersection  102  of a road can be an area surrounded by three or four road sections L1-L4, that is, the middle rectangular area defined by three or four road sections L1-L4 is the intersection  102 , but the road sections are not limited to four, and it may be more than four sections. Each of the road sections L1-L4 is provided with a traffic sign  104  (traffic light or pass/turn indicator) to control the vehicles passing through the intersection  102 , the pass direction of vehicles, and the pass time of vehicles. In addition, each intersection  102  has a traffic signal controller (not shown in the figure.). Through the network communication of the traffic signal controller, the traffic signal of each road section L1-L4 can be controlled in series, and the signs of each road section will not conflict to ensure the safety of vehicles passing through the intersection  102 . 
     In this embodiment, the signal receiving device  120  may be connected to or wirelessly communicate with the traffic signal controller (not shown in the figure) of the intersection  102  to receive a sign phase information  122  at the intersection and a road map information  124 . The sign phase information  122  includes signals, for example, red, yellow, green, left-turn green, right-turn green, and other signals. Road map information  124  includes, for example, the location of the intersection (e.g. the GPS coordinates of the center of the intersection), the type of intersection, the intersection area, the location of the sign, the position of the crossing lines, and the position of the stop line  106  of each road section, etc. 
     In this embodiment, the dynamic detection device  110  and the sign receiving device  120  can simultaneously input the external sensor information  112 , the road map information  124 , and the intersection sign phase information  122  corresponding to the intersection  102  for the message transmission system  100  to determine the objects near the intersection  102  in real time, the road map information  124 , and the intersection sign phase information  122  etc., as shown in  FIG.  2   . 
     Please refer to  FIG.  2   .  FIG.  2    is a schematic diagram of objects  101  at the intersection and their positions, speeds, and object moving directions according to an embodiment of the present disclosure. Each road section L1-L4 has two lanes in both directions, namely the lane leading to intersection  102  and the lane leaving intersection  102 . There are a total of eight lanes. Each lane has a plurality of objects  101  (that is, vehicles) driving on the road, each of the positions of the vehicles is detected, and the head of the vehicles is object moving direction. The italicized numbers next to the vehicles indicate the speed of each object. The speed will be adjusted dynamically according to the state of the vehicle. The speed of some vehicles that have left the intersection  102  is not displayed. The following is only an example showing the speed of vehicles approaching the intersection  102  as a basis for classification. In this embodiment, the dangerous object classification module  130  can analyze the position, the speed, the object moving direction, and the signs in object moving direction of each detected object passing through the intersection  102  to output the classification of dangerous objects of different groups. 
     Please refer to  FIGS.  1 A,  1 B, and  2   .  FIG.  1 B  is a schematic diagram of a message transmission method for a roadside equipment according to an embodiment of the present disclosure. The message transmission method includes the following steps S 110  to S 140 . In step S 110 , a plurality of external sensor information  112  is received. In step S 120 , an intersection sign phase information  122  and a road map information  124  are entered. In step S 130 , an object position analysis  132 , a speed analysis  134 , and a sign analysis  136  in object moving direction are performed based on the external sensor information  112 , the intersection sign phase message  122 , and the road map information  124 , and the classification of dangerous objects of different groups  139  is outputted. In step S 140 , a dangerous object message  142  with a higher dangerous object classification is preferentially selected and transmitted within an available transmission bandwidth. In such way, the present disclosure can send a dangerous object message  142  based on the degree of danger of the objects within the available transmission bandwidth, so as to reduce the transmission volume of vehicle-to-road communication. 
     A specific example of the classification of dangerous objects  139  has been shown in  FIGS.  3 A to  3 F .  FIG.  3 A  is a schematic diagram of the object position analysis  132  at the intersection according to an embodiment of the present disclosure;  FIG.  3 B  is a schematic diagram of objects at the intersection and the classification of dangerous objects in group D after the position analysis  132  of  FIG.  3 A ;  FIG.  3 C  is a schematic diagram of the sign analysis  136  in object moving direction and speed analysis  134  of the objects at the intersection according to an embodiment of the present disclosure:  FIG.  3 D  is a schematic diagram of the classification of dangerous objects at the intersection in groups C and D after the sign analysis  136  and speed analysis  134  of  FIG.  3 C ;  FIG.  3 E  is a schematic diagram of the analysis  138  of the degree of danger of the objects at the intersection according to an embodiment of the present disclosure;  FIG.  3 F  is a schematic diagram of the classification of dangerous objects at the intersection in groups A, B, C, and D after the analysis  138  of the degree of danger of  FIG.  3 E . 
     First, in  FIGS.  3 A and  3 B , the object position analysis  132  includes (a) determining whether the object  101  is on the road, and if so, continues (b) determining whether the object  101  is close to the intersection. If it is determined that the object  101  is not on the road, for example, the vehicles D1 and D2 parked on the side of the road are not dangerous to other driving vehicles, so this type of object  101  is classified into a dangerous object of group D. In addition, if it is determined that the object  101  is far away from the intersection, for example, vehicles D3 to D6, it means that the vehicle has passed the intersection or far enough away from the intersection, and is not dangerous for other driving vehicles, so this type of object  101  is classified into a dangerous object of group D. In addition, if it is determined that the object  101  is on the road and is close to the intersection  102 , for example, the vehicle C1, the sign analysis  136  in the object moving direction and the speed analysis  134  are performed to determine whether this type of object  101  is classified into a dangerous object of group C. It is understandable that the danger degree of the dangerous object of group C is higher than that of the dangerous object of group D. 
     Further, in  FIGS.  3 C and  3 D , the sign analysis  136  and speed analysis  134  of the object at the intersection include (a) determining whether the sign in object moving direction is a green light, if not, continue (b) determining whether the speed of the object is greater than a threshold. When the sign in object moving direction is a green light, the object  101  can be classified into a dangerous object of group C; when the sign in object moving direction is not green light and the speed of the object is less than the threshold, the object  101  can be classified into a dangerous object of group C; when the sign in object moving direction is not green light and the speed of the object is greater than the threshold, continue to perform the analysis  138  of degree of danger of the object to determine whether the object  101  is classified into a dangerous object of group B. 
     For example, in  FIG.  3 D , when the north-south lane is green light and the east-west lane is red light, the vehicles on the north-south lane are classified into dangerous objects of group C except for the classification of dangerous objects of group D. Then, when the speed of the vehicle in the east-west lane is less than the threshold (for example, 10 km/hr), for example, vehicles C2 and C3, it is not dangerous for the vehicles in the north-south lane, so this type of object  101  is classified into a dangerous object of group C. When the speed of the vehicle in the east-west lane is greater than a threshold, for example, vehicle B1, it may be dangerous to the vehicle in the north-south lane. An analysis  138  of the degree of danger of the object is performed to determine whether this type of object  101  is classified into a dangerous object of group B. It is understandable that the danger degree of the dangerous object of group B is higher than that of the dangerous object of group C. 
     Further, in addition to the above-mentioned object position analysis  132 , speed analysis  134 , and sign analysis  136  in object moving direction, the system  100  can perform an analysis  138  of the degree of danger based on the external sensor information  112 , intersection sign phase information  122 , and road map information  124 . In  FIGS.  3 E and  3 F , the analysis  138  of the degree of danger of the object at the intersection includes (a) determining whether the time from the object  101  to the intersection stop line  106  is greater than a threshold, if not, continues (b) determining whether the object  101  exceeds the stop line  106  . When the time from the object  101  to the stop line  106  of the intersection is greater than the threshold, the object  101  can be classified into a dangerous object of group B; when the time from the object  101  to the stop line  106  of the intersection is less than the threshold and the object  101  does not exceed the stop line  106 , the object  101  can be classified into a dangerous object of group B; when the time from the object  101  to the stop line  106  of the intersection is less than the threshold and the object  101  exceeds the stop line  106 , the object  101  can be classified into a dangerous object of group A. 
     For example, in  FIG.  3 F , when the east-west lane is red light, and the time from a vehicle on the east-west lane to the stop line  106  of the intersection is greater than a threshold, for example, the vehicle B1, it indicates that the vehicle is away from the stop line  106  about a certain distance, and it is still possible to stop without exceeding the stop line and is not dangerous for vehicles on the north-south lane. Therefore, this type of object  101  can be classified into a dangerous object of group B. When a vehicle in the east-west lane exceeds the stop line  106 , for example, the vehicle A1, it may collide with a vehicle in the north-south lane (e.g., the vehicle A2) at a next time, and this type of object  101  can be classified into a dangerous objects of group A. In this embodiment, when an object  101  with a high degree of danger (e.g., the vehicle A1) appears in the moving direction of the vehicle A2, the classification of the dangerous object of the vehicle A2 is increased to group A so as to have priority to send the dangerous object message  142  to the vehicles A1 and A2. It is understandable that the danger degree of the dangerous object of group A is higher than that of the dangerous object of group B, and the danger degree of the dangerous object of group B is higher than that of the dangerous object of group C. 
     In this embodiment, the vehicle-to-road communication device  140  preferentially selects and transmits a dangerous object message  142  with a higher dangerous object classification. In other words, the message of the dangerous object classification of group A is first transmitted, and then the message of the dangerous object classification of group B is transmitted, and then the messages of the dangerous object classification of group C and group D is finally transmitted. According to the limitation of the current transmission bandwidth and the classification of the degree of danger from high to low, the vehicle-to-road communication device  140  sends a message to notify the object  101  at the intersection to ensure that the system  100  can instantly send a dangerous object message  142  within the available transmission bandwidth, reduce a chance of collision of objects  101  at the intersection and reduce the transmission volume of vehicle-to-road communication. 
     The system  100  can scan the message of the surrounding vehicles at the intersection through radar and send the message through the roadside equipment with the function of dedicated short range communication (DSRC). The object messages at the intersection can be stored in the basic safety message (SAE J2735 BSM) and is broadcast regularly through exclusive short-range wireless communication. When the on-board unit (OBU) of auto-driving car receives this message and parses it, the safety collision avoidance system judges the message with its own information by algorithm to determine whether a collision will occur to make an action to stop the vehicle automatically. 
     For example, the internet of vehicles (V2X) technology is used on a road to improve the safety of auto-driving cars, and the primary task is how to make vehicles have safety protection during driving and reduce the incidence of traffic accidents. The disclosure can be used in the vehicle-to-vehicle transmission, vehicle-to-road transmission and intersection sign transmission to strengthen driving safety, avoid collisions at intersection, and give priority to warn the drivers whose vehicles are about to collide (for example, vehicles A1 and A2) to pay attention to driving safety. Therefore, when a vehicle equipped with on-board unit (OBU) approaches the roadside equipment and is about to pass through the intersection  102 , the OBU can receive the road map information  124 , sign phase information  122  at the intersection and the classification  139  of dangerous objects of the other vehicles from the system  100 , but it is not limited, the driver can see whether there is a dangerous object message  142  (such as a sound or a picture) according to the in-vehicle user interface to help the driver brake early or reduce the speed of the car. In addition, the disclosure can also be used in a left-turn anti-collision system to notify the driver of the dangerous object message  142  as soon as possible to prevent the driver’s vision from being blocked by the oncoming vehicle waiting to turn left when the vehicle is turning left and causing a danger of collision with a straight-moving vehicle. 
     Especially for objects without BSM capabilities (such as pedestrians, motorcycles, or cars without OBU), the basic safety message (BSM) packets can are sent to other vehicles through the broadcast mechanism of this system  100 , and the dangerous object messages  142  can be sent based on the limitation of the current transmission bandwidth and the degree of danger from high to low to reduce a chance of object collisions and reduce the transmission volume of vehicle-to-road communication to meet market demand. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.