C-V2X intelligent terminal for blind people to pass through intersection

Abstract

The invention discloses a C-V2X intelligent terminal for a blind person to pass through an intersection, and the terminal comprises a GNSS positioning unit which obtains the track information of the blind person in real time, and transmits the track information to a main processing unit; the C-V2X communication unit is used for receiving the traffic light color duration and intersection map information sent by the RSU and sending the traffic light color duration and intersection map information to the main processing unit; the main processing unit is used for calculating the traffic light color duration in the advancing direction of the blind person in real time, outputting the traffic light color and the remaining seconds in the advancing direction of the blind person through the audio interface unit, and broadcasting the advancing longitude, latitude, speed and azimuth angle information of the blind person through the C-V2X communication unit; and the power supply unit is used for supplying power to each unit. The terminal can obtain traffic signal machine traffic light information in real time, combines GNSS positioning information, broadcasts traffic light colors and remaining seconds in the advancing direction in a voice mode, and assists visually impaired people to safely and conveniently pass through an intersection.

Description

Technical Field

[0001] This invention belongs to the field of vehicle-road cooperative technology, specifically relating to a C-V2X smart terminal for blind people crossing intersections. Background Technology

[0002] Statistics show that there are approximately 17 million visually impaired people in my country, with about 8 million completely blind. Their need for mobility is urgent but limited; over 70% of visually impaired individuals require assistance when going out, and only about 9% can travel independently. While blind people can use guide dogs or canes to walk on roads, crossing the street, especially at complex intersections, is challenging due to the lack of voice prompts from traditional traffic lights. Blind people must rely on the sound of traffic flow to determine signals, leading to a high risk of accidents. To address this issue, most current guidance devices and methods use cameras and other visual means to identify traffic light information at intersections and then convert it into voice prompts to guide blind people across the street.

[0003] Using visual methods such as cameras to recognize traffic light information to assist blind people in crossing the road presents several problems in practical applications, as follows:

[0004] 1. The varied installation locations and shapes of traffic lights at intersections make them difficult to recognize.

[0005] 2. The camera angle of the guide equipment is limited, and in many cases the traffic light is not in the image of the camera, so the traffic light cannot be recognized;

[0006] 3. It is easily affected by the external environment, especially in environments such as backlight, rain, fog, and night.

[0007] 4. The data dimensions for recognition are limited, and the countdown information is not accurately recognized. Moreover, many pedestrian lights at intersections do not have countdown information, which also makes it impossible to recognize the countdown information.

[0008] 5. Recognizing traffic light information through computer vision requires visual aids to have high AI computing power, resulting in high power consumption and high cost.

[0009] In view of this, there is an urgent need for a reliable way to obtain traffic light information to help blind people cross the road safely and conveniently. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the present invention aims to provide a C-V2X intelligent terminal for blind people crossing intersections, solving the problems of low reliability, limited operating environment, high computational power dependence, and low recognition rate associated with existing visual methods such as cameras for recognizing traffic lights. The terminal of this invention can acquire real-time traffic light information from traffic signals and combine it with GNSS positioning information, providing voice announcements of the traffic light colors and remaining seconds for the direction of travel, assisting visually impaired individuals to cross intersections safely and conveniently.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0012] The present invention provides a C-V2X smart terminal for blind people to cross intersections, comprising: a main processing unit, a C-V2X communication unit, a GNSS positioning unit, an audio interface unit, and a power supply unit;

[0013] The GNSS positioning unit acquires the trajectory information of the blind person in real time and sends it to the main processing unit. The trajectory information includes longitude, latitude, speed and azimuth.

[0014] The C-V2X communication unit receives traffic light color duration and intersection map information sent by the roadside unit (RSU) and sends them to the main processing unit.

[0015] The main processing unit is used to calculate the duration of the traffic light color in the direction of travel for the blind person in real time, output the traffic light color and remaining seconds in the direction of travel for the blind person through the audio interface unit, and broadcast the longitude, latitude, speed and azimuth information of the blind person's travel through the C-V2X communication unit.

[0016] The power supply unit is used to supply power to each unit.

[0017] Furthermore, the C-V2X smart terminal also includes three guide buttons electrically connected to the main processing unit, which are used to select the direction of travel: left turn, straight ahead, and right turn.

[0018] Furthermore, the C-V2X communication unit conforms to the C-V2X R14 communication standard and has PC5 short-range communication capability. Two devices equipped with C-V2X communication units can communicate directly without going through a base station, and the communication latency is less than 10ms.

[0019] Furthermore, the GNSS positioning unit supports both BDS and GPS dual-satellite systems, conforms to the NMEA0183 protocol, and its positioning information includes longitude, latitude, speed, and azimuth.

[0020] Furthermore, the audio interface unit sends the traffic light colors and remaining seconds of the direction the blind person is traveling to the speaker connected to it for voice broadcast.

[0021] Furthermore, the main processing unit calculates the duration of the traffic light colors in the direction the blind person is traveling as follows:

[0022] (11) Based on the intersection map information, set the four vertices of the rectangle formed by the zebra crossings as location reference points, and use P R1 P R2 P R3 P R4 It means that P R1 PR2 , P R3 , P R4 , P R1 , P R1 , P R1 , P R2 , P R2 , P R2 , P R3 , P R3 , P R3 , P R4 , P R4 , P R4 , P R1 , P 11 , P 12 , P R2 , P 21 , P 22 , P R3 , P 31 , P 32 , P R4 , P 41 , P 42 ;

[0023] (12) respectively calculate the distance from the current time positioning point P t to P R1 , P R2 , P R3 , P R4 , the longitude of the positioning point P t is E t , the latitude is N t ;

[0024] Before distance calculation, the latitude and longitude coordinate values are converted into radian representation, the formula is as follows:

[0025]

[0026] Wherein, N is the latitude of the coordinate point, E is the longitude of the coordinate point, φ is the latitude of the coordinate point represented in radian, L is the longitude of the coordinate point represented in radian;

[0027] The distance s between the longitude and latitude coordinates P1 (φ1, L1) and P2 (φ2, L2) is calculated using the Vincenty formula, where φ1 is the latitude of the coordinate point P1 in radians, L1 is the longitude of the coordinate point P1 in radians, φ2 is the latitude of the coordinate point P2 in radians, and L2 is the longitude of the coordinate point P2 in radians;

[0028] The normalized latitudes U1 and U2 are calculated according to the following formula:

[0029] U1 = arctan((1-f)tanφ1)

[0030] U2 = arctan((1-f)tanφ2)

[0031] where f is the ellipsoid flattening, with a value of 1 / 298.257223563; U1 is the normalized latitude of φ1, and U2 is the normalized latitude of φ2;

[0032] The longitude difference ΔL is calculated according to the following formula:

[0033] ΔL = L2 - L1

[0034] The iteration variable λ is initialized to ΔL, and λ is iteratively solved according to the following formula: *

[0035]

[0036] cosσ = sinU1 sinU2 + cosU1 cosU2 cosλ

[0037] σ = arctan2(sinσ, cosσ)

[0038]

[0039] cos 2 α = 1 - sin 2 α

[0040]

[0041] λ * = ΔL + (1-C)fsinα(σ+Csinσ(cos(2σ m )+Ccosσ(-1+2cos 2 (2σ m ))))

[0042] Let λ = λ * , and repeat the iteration until |λ - λ * | < 10 -12 , where λ is the longitude difference on the auxiliary sphere before iteration, and λ * ​is the longitude difference on the auxiliary sphere after iteration, is the value of after one iteration according to the iteration formula above, is the angular distance, and is the auxiliary angle related to the azimuth angle m is the intermediate angle, and C is the auxiliary parameter

[0043] The distance auxiliary coefficient is calculated according to the following formula:

[0044]

[0045]

[0046] The distance s is calculated according to the following formula:

[0047] s = bA (σ - Δσ)

[0048] where u 2 is the auxiliary curvature parameter, A and B are series expansion coefficients, Δσ is the angular distance correction, s is the distance between the coordinate points P1 (φ1, L1) and P2 (φ2, L2), a is the equatorial radius with a value of 6378137.0 meters, and b is the polar radius, b = (1 - f) a, with a value of 6356752.314245 meters

[0049] The process of the blind person walking to the intersection, P t to P R1 , P R2 , P R3 , P R4 The distance gradually decreases, and the distance from P t to P R1 , P R2 , P R3 , P R4 is less than / equal to the threshold TH1, the value range of TH1 is [40, 60], TH1 is a real number; and the point with the shortest distance from P t to P R1 , P R2 , P R3 , P R4 is recorded as P Rx , the value range of the subscript x is [1, 4], x is a positive integer, and the blind person is closest to the point P Rx , that is, among the four position reference points, the blind person is closest to the point P Rx , the point P Rx corresponds to two red-green light pedestrian phases, which are recorded as PH x1 , PH x2 , and step (13) is entered;

[0050] (13) The azimuth angle C t of the blind person at time t is filtered to eliminate invalid values, and the filtered azimuth angle C As follows:

[0051] t = 1,

[0052] t > 1 (t is a positive integer), if |C t -C t-1 |≤ΔC M , if |C t -C t-1 |>ΔC M , wherein C t-1 is the azimuth angle at the previous moment, is the filtered azimuth angle at the previous moment, ΔC M is the filtering factor, ΔC M is a constant;

[0053] (14) judging the distance from P t to P Rx , when the distance from P t to P Rx is less than / equal to a threshold TH2, the value range of TH2 is [4, 6], TH2 is a real number, the blind person has approached the zebra crossing, generating voice prompt information and sending it to the audio interface unit for voice output, reminding the blind person that the zebra crossing has been approached, and judging the advancing direction pedestrian phase of the traffic light according to the selection information and the azimuth angle information sent by the guide key, for P Rx subscript x, when x is 1, if the azimuth angle is west to east and the guide key is straight, or the azimuth angle is north to south and the guide key is left turn, then the advancing direction pedestrian phase of the traffic light is north direction pedestrian west to east PH 11 , if the azimuth angle is west to east and the guide key is right turn, or the azimuth angle is north to south and the guide key is straight, then the advancing direction pedestrian phase of the traffic light is west direction pedestrian north to south PH 12 ; when x is 2, if the azimuth angle is east to west and the guide key is straight, or the azimuth angle is north to south and the guide key is right turn, then the advancing direction pedestrian phase of the traffic light is north direction pedestrian east to west PH 21 , if the azimuth angle is east to west and the guide key is left turn, or the azimuth angle is north to south and the guide key is straight, then the advancing direction pedestrian phase of the traffic light is east direction pedestrian north to south PH 22 ; when x is 3, if the azimuth angle is east to west and the guide key is straight, or the azimuth angle is south to north and the guide key is left turn, then the advancing direction pedestrian phase of the traffic light is south direction pedestrian east to west PH 31 , if the azimuth angle is east to west and the guide key is right turn, or the azimuth angle is south to north and the guide key is straight, then the advancing direction pedestrian phase of the traffic light is east direction pedestrian south to north PH 32; when x is 4, if the azimuth angle is west to east and the guide button is straight, or the azimuth angle is south to north and the guide button is right turn, then the walking direction traffic light pedestrian phase is south direction pedestrian west to east PH 41 , if the azimuth angle is west to east and the guide button is left turn, or the azimuth angle is south to north and the guide button is straight, then the walking direction traffic light pedestrian phase is west direction pedestrian north to south PH 42 ;

[0054] (15) Analyzing the traffic light color duration information, the north direction pedestrian west to east phase color duration is represented by M 11 , the west direction pedestrian north to south phase color duration is represented by M 12 , the north direction pedestrian east to west phase color duration is represented by M 21 , the east direction pedestrian north to south phase color duration is represented by M 22 , the south direction pedestrian east to west phase color duration is represented by M 31 , the east direction pedestrian south to north phase color duration is represented by M 32 , the south direction pedestrian west to east phase color duration is represented by M 41 , the west direction pedestrian south to north phase color duration is represented by M 42 ; if the walking direction traffic light pedestrian phase is PH xy , then the corresponding blind person walking direction traffic light color duration information is M xy , y takes the value range of [1, 2], y is a positive integer;

[0055] (16) Calculating the distance from the blind person's current positioning point P t to the reference point P Rz on the opposite side of the zebra crossing, the subscript z takes the value range of [1, 4], z is a positive integer, when the distance is less than / equal to the threshold value TH3, TH3 takes the value range of [1, 3], TH3 is a real number, send a prompt information to the audio interface unit to remind the blind person that the zebra crossing will be passed, if the blind person continues to pass the current intersection request sent by the guide button at this time, then for P Rz , when z is 1, if the azimuth angle is east to west and the guide button is left turn, then the corresponding traffic light pedestrian phase of the blind person continuing to pass the current intersection is west direction pedestrian north to south PH 12 , if the azimuth angle is south to north and the guide button is right turn, then the corresponding traffic light pedestrian phase of the blind person continuing to pass the current intersection is north direction pedestrian west to east PH 11 ; when z is 2, if the azimuth angle is west to east and the guide button is right turn, then the corresponding traffic light pedestrian phase of the blind person continuing to pass the current intersection is east direction pedestrian north to south PH 22 , if the azimuth angle is south to north and the guide button is left turn, then the corresponding traffic light pedestrian phase of the blind person continuing to pass the current intersection is north direction pedestrian east to west PH21 ; when z is 3, if the azimuth angle is west to east, the guide button is left turn, then the pedestrian phase of the red and green light corresponding to the current intersection that the blind person continues to pass through is the east direction pedestrian south to north PH 32 , if the azimuth angle is north to south, the guide button is right turn, then the pedestrian phase of the red and green light corresponding to the current intersection that the blind person continues to pass through is the south direction pedestrian east to west PH 31 ; when z is 4, if the azimuth angle is east to west, the guide button is right turn, then the pedestrian phase of the red and green light corresponding to the current intersection that the blind person continues to pass through is the west direction pedestrian south to north PH 42 , if the azimuth angle is north to south, the guide button is left turn, then the pedestrian phase of the red and green light corresponding to the current intersection that the blind person continues to pass through is the south direction pedestrian west to east PH 41 ; the red and green light color duration information of the direction that the blind person continues to pass through the current intersection is calculated.

[0056] The beneficial effects of the present application are as follows:

[0057] 1. The present application directly obtains the red and green light information in the C-V2X communication mode, which is safe and reliable, low in time delay, and avoids the problems of being easily blocked, limited use environment, low recognition accuracy and dependence on computing power in the visual recognition of the red and green light.

[0058] 2. The present application can quickly and accurately determine the position of the blind person at the intersection, and in combination with the azimuth angle filtering processing and the guide button, the pedestrian phase of the blind person passing through the intersection can be correctly judged, so that the pedestrian light color and the remaining time duration information of the direction of travel can be accurately pushed to the blind person through the voice broadcast mode.

[0059] 3. In the process of the blind person passing through the zebra crossing, the latitude and longitude, speed and direction angle information of the blind person are broadcast to the vehicles near the C-V2X communication unit, which can remind the driver to slow down and observe carefully, so as to ensure the safety of the blind person passing through the intersection and avoid traffic accidents. BRIEF DESCRIPTION OF DRAWINGS

[0060] Figure 1 It is the principle block diagram of the C-V2X intelligent terminal of the present application.

[0061] Figure 2 It is the communication schematic diagram of the C-V2X intelligent terminal and the roadside equipment and the vehicle side equipment.

[0062] Figure 3 It is the crossroad P R1 , P R2 , P R3 , P R4 point position schematic diagram.

[0063] Figure 4 It is the T-shaped intersection P R1 , PR2 , P R3 , P R4 Point position schematic diagram.

[0064] Figure 5 A word intersection P R1 , P R2 , P R3 , P R4 Point position schematic diagram.

[0065] Figure 6 Satellite map of a certain city road intersection. DETAILED DESCRIPTION

[0066] In order to facilitate the understanding of those skilled in the art, the present application will be further described below in conjunction with the embodiments and the accompanying drawings. The content mentioned in the embodiments is not a limitation of the present application.

[0067] Referring to Figure 1 , a C-V2X intelligent terminal for blind people crossing intersections of the present application, comprising: a main processing unit, a C-V2X communication unit, a GNSS positioning unit, an audio interface unit and a power supply unit;

[0068] The GNSS positioning unit acquires real-time trajectory information of the blind person and sends it to the main processing unit. The trajectory information includes longitude, latitude, speed and azimuth.

[0069] The GNSS positioning unit supports both BDS and GPS dual-satellite systems and conforms to the NMEA0183 protocol. The positioning information includes longitude, latitude, speed and azimuth.

[0070] The C-V2X communication unit receives the red and green light color duration and intersection map information sent by the road side device RSU and sends it to the main processing unit.

[0071] The C-V2X communication unit conforms to the C-V2X R14 communication standard and has PC5 short-range communication capability. Two devices with C-V2X communication unit can communicate directly without going through the base station, and the communication delay is less than 10ms.

[0072] The main processing unit is used for real-time calculation to obtain the red and green light color duration of the blind person's travel direction, and outputs the red and green light color and the remaining seconds of the blind person's travel direction through the audio interface unit. The longitude, latitude, speed and azimuth information of the blind person's travel are broadcasted through the C-V2X communication unit.

[0073] The power supply unit is used for power supply to each unit.

[0074] Specifically, the C-V2X smart terminal also includes three guide buttons electrically connected to the main processing unit, which are used to select the direction of travel: left turn, straight ahead, and right turn.

[0075] Specifically, the audio interface unit sends the traffic light colors and remaining seconds of the direction the blind person is traveling to the speaker connected to it for voice broadcast.

[0076] Specifically, the main processing unit calculates the duration of the traffic light colors in the direction the blind person is traveling as follows:

[0077] (11) Based on the intersection map information, set the four vertices of the rectangle formed by the zebra crossings as location reference points, and use P R1 P R2 P R3 P R4 It means that P R1 P R2 P R3 P R4 The latitude and longitude information is constant, namely P R1 (E R1 N R1 ), P R2 (E R2 N R2 ), P R3 (E R3 N R3 ), P R4 (E R4 N R4 Add a mapping relationship between 4 location reference points and traffic light phase information, P R1 The pedestrian phases corresponding to the two traffic lights at the point are: northbound pedestrians traveling west to east, and westbound pedestrians traveling north to south, denoted by PH respectively. 11 pH 12 Indicates; P R2 The two pedestrian traffic light phases corresponding to the point are: pedestrians traveling from north to west and pedestrians traveling from east to south, denoted by PH respectively. 21 pH 22 Indicates; P R3 The two pedestrian traffic light phases corresponding to the point are: pedestrians traveling from south to east and from east to north, denoted by PH respectively. 31 pH 32 Indicates; P R4 The two pedestrian traffic light phases corresponding to the point are: pedestrians traveling from south to east and pedestrians traveling from west to north, denoted by PH respectively. 41 pH 42 express;

[0078] (12) Calculate the current location point P at the current time. t To P R1 PR2 , P R3 , P R4 distance, the location point P t longitude is E t , latitude is N t ;

[0079] Before distance calculation, the latitude and longitude coordinate values are converted into radian representation, and the formula is as follows:

[0080]

[0081] Wherein, N is the latitude of the coordinate point, E is the longitude of the coordinate point, φ is the latitude of the coordinate point represented by radian, and L is the longitude of the coordinate point represented by radian;

[0082] The Vincenty formula is used to calculate the distance s between the latitude and longitude coordinates P1(φ1, L1) and P2(φ2, L2), φ1 is the latitude of the coordinate point P1 represented by radian, L1 is the longitude of the coordinate point P1 represented by radian, φ2 is the latitude of the coordinate point P2 represented by radian, and L2 is the longitude of the coordinate point P2 represented by radian;

[0083] The normalized latitude U1 and U2 are calculated, and the formula is as follows:

[0084] U1 = arctan((1-f)tanφ1)

[0085] U2 = arctan((1-f)tanφ2)

[0086] Wherein, f is the ellipsoid flattening, and the value is 1 / 298.257223563; U1 is the normalized latitude of φ1, and U2 is the normalized latitude of φ2;

[0087] The longitude difference ΔL is calculated, and the formula is as follows:

[0088] ΔL = L2-L1

[0089] Initialize the iteration variable λ = ΔL, and iteratively solve λ * , and the iteration formula is as follows:

[0090]

[0091] cosσ = sinU1sinU2 + cosU1cosU2cosλ

[0092] σ = arctan2(sinσ, cosσ)

[0093]

[0094] cos 2 α = 1-sin 2α

[0095]

[0096] λ * =ΔL+(1-C)fsinα(σ+Csinσ(cos(2σ m )+Ccosσ(-1+2cos 2 (2σ m ))))

[0097] Let λ = λ * Repeat the iteration until |λ-λ * |<10 -12 , where λ is the longitude difference on the auxiliary sphere before iteration, λ * The longitude difference on the auxiliary sphere after iteration is the value of λ after one iteration according to the above iterative formula, σ is the angular distance, and α is the auxiliary angle related to the azimuth. m C is the median angle, and C is an auxiliary parameter.

[0098] The distance auxiliary coefficient is calculated using the following formula:

[0099]

[0100] The formula for calculating distance s is as follows:

[0101] s=bA(σ-Δσ)

[0102] Among them, u 2 A is the auxiliary curvature parameter; A and B are the series expansion coefficients; Δσ is the angular distance correction; s is the distance between coordinate points P1(φ1,L1) and P2(φ2,L2); a is the equatorial radius, with a value of 6378137.0 meters; b is the polar radius, b=(1-f)a, with a value of 6356752.314245 meters.

[0103] The process of a blind person walking towards an intersection, P t To P R1 P R2 P R3 P R4 The distance gradually decreased, and P was detected for the first time. t To P R1 P R2 P R3 P R4 When the distance to any point is less than or equal to the threshold TH1, the value of TH1 ranges from [40, 60], and TH1 is a real number; record P. t To P R1 P R2 P R3 P R4 The point with the shortest distance is P.Rx The subscript x takes values ​​in the range [1, 4], where x is a positive integer, and the distance P for the blind person is... Rx The closest point is P, meaning that among the four reference points, the blind person is closest to P. Rx Point, P Rx The point corresponds to the pedestrian phase of two traffic lights, denoted as PH. x1 pH x2 Proceed to step (13);

[0104] (13) The azimuth angle C at time t when the blind person is walking. t After filtering to remove invalid values, the azimuth angle at time t is obtained. as follows:

[0105] When t=1,

[0106] When t>1 (t is a positive integer), if |C t -C t-1 |≤ΔC M , If |C t -C t-1 |>ΔC M , Among them, C t-1 The azimuth angle at the previous moment. The azimuth angle after filtering at the previous moment, ΔC M ΔC is the filter factor. M It is a constant;

[0107] (14) Determine P t To P Rx The distance when P t To P Rx When the distance is less than or equal to the threshold TH2, where TH2 ranges from [4,6] and is a real number, the blind person has approached the zebra crossing. A voice prompt is generated and sent to the audio interface unit for voice output, reminding the blind person that they are approaching the zebra crossing. Based on the selection information and azimuth information sent by the guide button, the pedestrian phase of the traffic light is determined, and for P... Rx Subscript x: When x is 1, if the azimuth is west to east and the guide button is straight, or if the azimuth is north to south and the guide button is left turn, then the pedestrian phase of the traffic light is north-facing pedestrian west to east PH. 11 If the azimuth is west to east and the guide button is right turn, or if the azimuth is north to south and the guide button is straight, then the pedestrian phase of the traffic light for the direction of travel is west pedestrian north to south PH. 12 When x is 2, if the azimuth is east to west and the guide button is straight, or the azimuth is north to south and the guide button is right turn, then the pedestrian phase of the traffic light in the direction of travel is north-facing pedestrian east to west PH.21 , if the azimuth angle is east to west and the guide button is left turn, or the azimuth angle is north to south and the guide button is straight, the walking direction traffic light pedestrian phase is east direction pedestrian north to south PH 22 ; when x is 3, if the azimuth angle is east to west and the guide button is straight, or the azimuth angle is south to north and the guide button is left turn, the walking direction traffic light pedestrian phase is south direction pedestrian east to west PH 31 , if the azimuth angle is east to west and the guide button is right turn, or the azimuth angle is south to north and the guide button is straight, the walking direction traffic light pedestrian phase is east direction pedestrian south to north PH 32 ; when x is 4, if the azimuth angle is west to east and the guide button is straight, or the azimuth angle is south to north and the guide button is right turn, the walking direction traffic light pedestrian phase is south direction pedestrian west to east PH 41 , if the azimuth angle is west to east and the guide button is left turn, or the azimuth angle is south to north and the guide button is straight, the walking direction traffic light pedestrian phase is west direction pedestrian south to north PH 42 ;

[0108] (15) Analyzing the traffic light color duration information, the north direction pedestrian west to east phase color duration is represented by M 11 , the west direction pedestrian north to south phase color duration is represented by M 12 , the north direction pedestrian east to west phase color duration is represented by M 21 , the east direction pedestrian north to south phase color duration is represented by M 22 , the south direction pedestrian east to west phase color duration is represented by M 31 , the east direction pedestrian south to north phase color duration is represented by M 32 , the south direction pedestrian west to east phase color duration is represented by M 41 , the west direction pedestrian south to north phase color duration is represented by M 42 ; if the walking direction traffic light pedestrian phase is PH xy , the corresponding blind person walking direction traffic light color duration information is M xy , y takes the value range of [1, 2], y is a positive integer;

[0109] (16) Calculate the distance between the blind person's current positioning point P t and the reference point P Rz on the opposite side of the zebra crossing, the value range of the subscript z is [1, 4], z is a positive integer, when the distance is less than / equal to the threshold TH3, the value range of TH3 is [1, 3], TH3 is a real number, send a prompt information to the audio interface unit to remind the blind person that the zebra crossing will be passed, if the blind person continues to pass the current intersection request sent by the guide button at this time, then for P RzThe subscript z, when z is 1, if the azimuth angle is east to west and the guide button is left turn, then the pedestrian phase of the red light at the current intersection corresponding to the pedestrian phase of the red light is west to east PH 12 , if the azimuth angle is south to north and the guide button is right turn, then the pedestrian phase of the red light at the current intersection corresponding to the pedestrian phase of the red light is north to south PH 11 ; when z is 2, if the azimuth angle is west to east and the guide button is right turn, then the pedestrian phase of the red light at the current intersection corresponding to the pedestrian phase of the red light is east to west PH 22 , if the azimuth angle is south to north and the guide button is left turn, then the pedestrian phase of the red light at the current intersection corresponding to the pedestrian phase of the red light is north to south PH 21 ; when z is 3, if the azimuth angle is west to east and the guide button is left turn, then the pedestrian phase of the red light at the current intersection corresponding to the pedestrian phase of the red light is east to west PH 32 , if the azimuth angle is south to north and the guide button is right turn, then the pedestrian phase of the red light at the current intersection corresponding to the pedestrian phase of the red light is north to south PH 31 . When z is 4, if the azimuth angle is east to west and the guide button is right turn, then the pedestrian phase of the red light at the current intersection corresponding to the pedestrian phase of the red light is east to west PH 42 , if the azimuth angle is south to north and the guide button is left turn, then the pedestrian phase of the red light at the current intersection corresponding to the pedestrian phase of the red light is north to south PH 41 ; the red light color duration information of the blind person continuing to pass through the current intersection is calculated.

[0110] In the example,

[0111] Referring to FIG. 1, Figure 2 As shown, the C-V2X intelligent terminal receives the intersection map information broadcast by the roadside device RSU, and the four vertices of the rectangular frame composed of the zebra crossing are P R1 , P R2 , P R3 , P R4 , because the map information of the intersection is fixed, the longitude and latitude information of P R1 , P R2 , P R3 , P R4 is also determined and constant, denoted as P R1 (E R1 , N R1 ), P R2 (E R2 , N R2 ), P R3 (E R3 , N R3 ), P R4 (E R4 , N R4). For the intersection, the rectangular frame selected point is shown in Figure 3 ; for the T-shaped intersection, the rectangular frame selected point is shown in Figure 4 ; for the one-word intersection, the rectangular frame selected point is shown in Figure 5 . For a certain city road intersection, as shown in Figure 6 , the 4 vertices of the rectangular frame composed of the zebra crossing are P R1 (118.864856, 32.01270), P R2 (118.865273, 32.01265), P R3 (118.865271, 32.01229), and P R4 (118.864805, 32.01230). The blind person is walking from north to south on the northwest side of the intersection and is ready to straight pass through the intersection.

[0112] The C-V2X intelligent terminal obtains the GNSS positioning information at the current time in real time, records the longitude as E t , the latitude as N t , the positioning point as P t (E t , N t ), and calculates the distances from P t to P R1 , P R2 , P R3 , and P R4 according to the Vincenty formula. During the process of the blind person walking to the intersection, the distances from P t to P R1 , P R2 , P R3 , and P R4 are gradually reduced. When the distance from P t to any of P R1 , P R2 , P R3 , and P R4 is less than or equal to the threshold TH1 (the threshold TH1 is 50 meters in this example), the point with the shortest distance from P t to P R1 , P R2 , P R3 , and P R4 is recorded as P Rx , and the blind person is closest to the point P Rx , that is, among the 4 position reference points, the blind person is closest to the point P Rx . As shown in Figure 6 , the blind person takes the longitude and latitude positioning information every second during the walking process. The longitude and latitude coordinates of the blind person at T0 are recorded as (118.864953, 32.01370). At this time, the distance from P to PR1 P R2 P R3 P R4 The distances are 111.6 meters, 120.6 meters, 159.6 meters, and 156.3 meters, respectively, all greater than 50 meters. The coordinates of the blind person's trajectory from point P are calculated once per second. R1 P R2 P R3 P R4 The distance, recorded as P detected at time T1. t To P R1 P R2 P R3 P R4 The distance to any point is less than or equal to TH1 meters. At this time, the latitude and longitude coordinates of the blind person are... (118.864952, 32.01314), calculated using Vincenty's formula, at this time... To P R1 P R2 P R3 P R4 The distances are 49.7 meters, 62.3 meters, 99.2 meters, and 94.4 meters respectively. Therefore, it can be known that... Away from P R1 Point P is the closest at this time. Rx That is, P R1 The C-V2X smart terminal can determine that a blind person is in P. R1 P R1 The pedestrian phases of the two traffic lights corresponding to the point are: northbound pedestrians and westbound pedestrians. 11 Pedestrians from the west to the south PH 12 ;

[0113] The azimuth angle information of the blind person as they walk is acquired in real time, and samples are taken every 500 milliseconds. The azimuth angle sampled at time t is denoted as C. t As a blind person walks from north to south on the northwest side of the intersection, they continuously record the azimuth angles, such as {180.9, 180.0, 179.2, 180.9, 221.1, 179.4, 179.9, 185.1, 183.5, 183.8}, denoted as {C}. Before filtering the azimuth angles, ΔC needs to be... M The filter factor value, ΔC M The value range is (0, 180), ΔC M The smaller the value, especially when it approaches 0, the more likely the normal azimuth angle will be filtered out, ΔC M If the value is too large, abnormal azimuth angles will not be filtered out. Therefore, it is necessary to select an appropriate filter factor value based on the actual filtering effect. In this embodiment, ΔC... MThe value is set to 20. Following the filtering formula above, {C} is filtered, resulting in azimuth angles of {180.9, 180.45, 179.6, 180.05, 180.05, 180.05, 179.65, 182.5, 184.3, 183.65}. The C-V2X smart terminal can then determine that the blind person is walking from north to south.

[0114] The blind person continues walking, and time P is recorded as T2. t To P R1 If the distance is less than or equal to the threshold TH2 (TH2 is 5 meters in this example), then the blind person's latitude and longitude coordinates are... (118.864868, 32.01274), because P R1 The coordinates of point P are (118.864856, 32.01270), and the distance between the two points is 4.6 meters. The C-V2X smart terminal can determine that the blind person is approaching the zebra crossing and will issue a voice reminder that the blind person is approaching the zebra crossing. Since the blind person is traveling from north to south and needs to cross the intersection straight, the blind person presses the straight guidance button on the C-V2X smart terminal. At this time, for P... Rx The subscript x has a value of 1, the azimuth is north to south, the guide button is straight, then the pedestrian phase of the traffic light is west-facing pedestrian north-south PH. 12 At this point, the traffic light color duration information is analyzed to retrieve pedestrian light information for the direction of travel, specifically the phase light color duration information M for pedestrians traveling west and north to south. 12 The system uses voice announcements to push the light color and remaining duration information for the current phase to blind people, broadcasting it every 5 seconds to assist them in crossing the zebra crossing. While the blind person is crossing, the C-V2X smart terminal broadcasts their longitude, latitude, speed, and azimuth information via the C-V2X communication unit, providing safety warnings to nearby vehicles equipped with C-V2X communication units. Simultaneously, the C-V2X smart terminal detects the blind person's latitude, longitude, and azimuth in real time based on the pressed guidance button, comparing it with the direction selected by the button to prevent discrepancies between the actual and selected directions, thus ensuring the blind person's safe passage across the zebra crossing. For example, when choosing a direction of travel, the blind person should have pressed the straight button but mistakenly pressed the left turn button. At this time, the left turn is the pedestrian phase for the north direction. The C-V2X smart terminal assumes that the blind person will cross the north-facing zebra crossing from west to east, with a azimuth angle of about 90 degrees. If the north-facing pedestrian phase is green at this time, the blind person will start to walk straight, with an azimuth angle of about 180 degrees from north to south. The two azimuth angles are significantly different. The C-V2X smart terminal can then determine that the blind person's actual direction of travel is inconsistent with the direction selected by the guidance button and provide a voice reminder that the actual direction of travel is inconsistent with the direction selected by the guidance button, thereby preventing the blind person from accidentally running a red light.

[0115] During the process of a blind person crossing a zebra crossing, record the blind person's location point P at time T3. t Reference point P on the other side of the zebra crossing R4 If the distance is less than or equal to the threshold TH3 (threshold TH3 is 3 meters in this example), then the blind person's latitude and longitude coordinates are... (118.864812, 32.01232), because P R4 The coordinates of point P are (118.864805, 32.01230), and the distance between the two points is 2.3 meters, indicating that the blind person is about to cross the zebra crossing. At this time, the C-V2X smart terminal provides a voice reminder to the blind person that they are about to cross the zebra crossing. If the blind person still needs to cross the intersection and presses the left turn button, for P... Rz If the subscript z has a value of 4 and the azimuth is north to south, then the pedestrian phase at the current intersection's traffic light is southbound (PH) and westbound (PH). 41 Analyze the traffic light color duration message and extract the pedestrian west-to-east phase color duration information M. 41 The voice prompts are given to the blind person, and they are guided to cross the road until they are far from the intersection and no longer need to cross the road.

[0116] This invention has many specific applications. The above description is only a preferred embodiment of this invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of this invention, and these improvements should also be considered within the scope of protection of this invention.

Claims

1.A C-V2X intelligent terminal for blind people crossing an intersection, characterized in that, Comprise: The main processing unit, C-V2X communication unit, GNSS positioning unit, audio interface unit and power supply unit; The GNSS positioning unit acquires the blind person's trajectory information in real time and sends it to the main processing unit, and the trajectory information includes longitude, latitude, speed and azimuth; The C-V2X communication unit receives the traffic light color duration and intersection map information sent by the road side device RSU and sends it to the main processing unit; The main processing unit is used for real-time calculation to obtain the traffic light color duration of the blind person's travel direction, and outputs the traffic light color and the remaining seconds of the blind person's travel direction through the audio interface unit, and broadcasts the longitude, latitude, speed and azimuth information of the blind person's travel through the C-V2X communication unit; The power supply unit is used for power supply to each unit. 2.The C-V2X intelligent terminal for blind people crossing intersection of claim 1, wherein, The C-V2X intelligent terminal further comprises three guide keys electrically connected with the main processing unit, which are respectively used for selecting the travel direction of left turn, straight and right turn. 3.The C-V2X intelligent terminal for blind people crossing intersection of claim 1, wherein, The C-V2X communication unit conforms to the C-V2X R14 communication standard and has PC5 short-range communication capability. Two devices with C-V2X communication unit can directly communicate without passing through the base station, and the communication delay is less than 10ms. 4.The C-V2X intelligent terminal for blind people crossing intersection of claim 1, wherein, The GNSS positioning unit supports BDS and GPS dual satellite systems simultaneously and conforms to the NMEA0183 protocol. The positioning information includes longitude, latitude, speed and azimuth. 5.The C-V2X intelligent terminal for blind people crossing intersection of claim 1, wherein, The audio interface unit sends the traffic light color and the remaining seconds of the blind person's travel direction to the loudspeaker connected therewith for voice broadcast. 6.The C-V2X intelligent terminal for blind people crossing intersection of claim 1, wherein, The main processing unit calculates the traffic light color duration of the blind person's travel direction as follows: (11) Based on intersection map information, set the 4 vertices of the rectangular frame composed of zebra crossing as position reference points, with P R1 , P R2 , P R3 , P R4 representing the latitude and longitude information of P R1 , P R2 , P R3 , P R4 as constants, respectively P R1 (E R1 , N R1 ), P R2 (E R2 , N R2 ), P R3 (E R3 , N R3 ), P R4 (E R4 , N R4 ), add the mapping relationship of 4 position reference points and traffic light phase information, P R1 point corresponds to two traffic light pedestrian phases of north direction pedestrian west to east and west direction pedestrian north to south, respectively represented by PH 11 , PH 12 ; P R2 point corresponds to two traffic light pedestrian phases of north direction pedestrian east to west and east direction pedestrian north to south, respectively represented by PH 21 , PH 22 ; P R3 point corresponds to two traffic light pedestrian phases of south direction pedestrian east to west and east direction pedestrian south to north, respectively represented by PH 31 , PH 32 ; P R4 point corresponds to two traffic light pedestrian phases of south direction pedestrian west to east and west direction pedestrian south to north, respectively represented by PH 41 , PH 42 ; (12) Calculate the distance from the positioning point P t to P R1 , P R2 , P R3 , P R4 , respectively, and the longitude of the positioning point P t is E t , the latitude is N t ; Before distance calculation, the latitude and longitude coordinate values are converted into radian representation, and the formula is as follows: Wherein, N is the latitude of the coordinate point, E is the longitude of the coordinate point, φ is the latitude of the coordinate point represented in radian, and L is the longitude of the coordinate point represented in radian. The Vincenty formula is used to calculate the distance s between the latitude and longitude coordinates P1(φ1, L1) and P2(φ2, L2), φ1 is the latitude of coordinate point P1 represented in radian, L1 is the longitude of coordinate point P1 represented in radian, φ2 is the latitude of coordinate point P2 represented in radian, and L2 is the longitude of coordinate point P2 represented in radian. Calculate the normalized latitude U1, U2, and the formula is as follows: U1=arctan((1-f)tanφ1) U2=arctan((1-f)tanφ2) Wherein, f is the flattening of the ellipsoid, and the value is 1 / 298.257223563; U1 is the normalized latitude of φ1, and U2 is the normalized latitude of φ2. Calculate the longitude difference ΔL, and the formula is as follows: ΔL=L2-L1 Initialize the iteration variable λ = ΔL, and solve for λ iteratively * The iteration formula is as follows: cosσ=sinU1sinU2+cosU1cosU2cosλ σ=arctan2(sinσ,cosσ) cos 2 α = 1 - sin 2 α λ * = AL+ (1 - C) f sin a (s + C sin s (cos (2s m )+ C cos s (-1 + 2 cos 2 (2s m )))) Let λ = λ * , repeat the iteration until |λ - λ * | < 10 -12 , where λ is the longitude difference on the auxiliary sphere before iteration, λ * is the longitude difference on the auxiliary sphere after iteration, is the value of λ after one iteration according to the iteration formula, σ is the angular distance, α is the auxiliary angle related to the azimuth angle, σ m is the intermediate angle, and C is an auxiliary parameter; Calculate the distance auxiliary coefficient, and the formula is as follows: Calculate the distance s, and the formula is as follows: s=bA(σ-Δσ) where u 2 is an auxiliary curvature parameter; A, B are series expansion coefficients; Δσ is an angular distance correction, s is the distance between coordinate points P1(φ1, L1) and P2(φ2, L2), a is the equatorial radius, b is the polar radius, b = (1 - f)a; The process of a blind person walking towards an intersection, P t To P R1 P R2 P R3 P R4 The distance gradually decreased, and P was detected for the first time. t To P R1 P R2 P R3 P R4 When the distance to any point is less than or equal to the threshold TH1, the value of TH1 ranges from [40, 60], and TH1 is a real number; record P. t To P R1 P R2 P R3 P R4 The point with the shortest distance is P. Rx The subscript x takes values ​​in the range [1, 4], where x is a positive integer, and the distance P for the blind person is... Rx The closest point is P, meaning that among the four reference points, the blind person is closest to P. Rx Point, P Rx The point corresponds to the pedestrian phase of two traffic lights, denoted as PH. x1 pH x2 Proceed to step (13); (13) the azimuth angle C at time t when the blind person is walking t The filtering process is performed to eliminate invalid values, and the filtered azimuth angle at time t is obtained As follows: t = 1, t>1, if |C t -C t-1 |≤ΔC M , t>1, if |C t -C t-1 |>ΔC M , where C t-1 is the azimuth angle at the last time, is the filtered azimuth angle at the last time, ΔC M is the filter factor, and ΔC M is a constant. (14) Determine P t To P Rx The distance when P t To P Rx When the distance is less than or equal to the threshold TH2, where TH2 ranges from [4,6] and is a real number, the blind person has approached the zebra crossing. A voice prompt is generated and sent to the audio interface unit for voice output, reminding the blind person that they are approaching the zebra crossing. Based on the selection information and azimuth information sent by the guide button, the pedestrian phase of the traffic light is determined, and for P... Rx Subscript x: When x is 1, if the azimuth is west to east and the guide button is straight, or if the azimuth is north to south and the guide button is left turn, then the pedestrian phase of the traffic light is north-facing pedestrian west to east PH. 11 If the azimuth is west to east and the guide button is right turn, or if the azimuth is north to south and the guide button is straight, then the pedestrian phase of the traffic light for the direction of travel is west pedestrian north to south PH. 12 When x is 2, if the azimuth is east to west and the guide button is straight, or the azimuth is north to south and the guide button is right turn, then the pedestrian phase of the traffic light in the direction of travel is north-facing pedestrian east to west PH. 21 If the azimuth is east to west and the guide button is left turn, or the azimuth is north to south and the guide button is straight, and the pedestrian phase of the traffic light is east-facing pedestrians north-facing pedestrians (PH), then... 22 When x is 3, if the azimuth is east to west and the guide button is straight, or if the azimuth is south to north and the guide button is left turn, then the pedestrian phase of the traffic light in the direction of travel is south-facing pedestrian east to west PH. 31 If the azimuth is east to west and the guide button is right turn, or if the azimuth is south to north and the guide button is straight, then the pedestrian phase of the traffic light for the direction of travel is east-facing pedestrian south-facing pedestrian PH. 32 When x is 4, if the azimuth is west to east and the guide button is straight, or if the azimuth is south to north and the guide button is right turn, then the pedestrian phase of the traffic light in the direction of travel is south-facing pedestrian west to east PH. 41 If the azimuth is west to east and the guide button is left turn, or if the azimuth is south to north and the guide button is straight, then the pedestrian phase of the traffic light is west-facing pedestrians south-facing pedestrians (PH). 42 ; (15) The red light color duration information is parsed, and the north direction pedestrian west-east phase light color duration is represented by M 11 The west direction pedestrian north-south phase light color duration is represented by M 12 The north direction pedestrian east-west phase light color duration is represented by M 21 The east direction pedestrian north-south phase light color duration is represented by M 22 The south direction pedestrian east-west phase light color duration is represented by M 31 The east direction pedestrian south-north phase light color duration is represented by M 32 The south direction pedestrian west-east phase light color duration is represented by M 41 The west direction pedestrian south-north phase light color duration is represented by M 42 It is represented that if the red light pedestrian phase of the running direction is PH xy , then the corresponding blind person running direction red light color duration information is M xy , and y is a positive integer in the range of [1, 2]. (16) Calculate the current location point P of the blind person during the process of crossing the zebra crossing. t Reference point P on the other side of the zebra crossing Rz The distance is given by the subscript z, which ranges from [1, 4] and is a positive integer. When the distance is less than or equal to the threshold TH3, the value of TH3 ranges from [1, 3] and is a real number. A prompt message is sent to the audio interface unit to remind the blind person that they are about to cross the zebra crossing. If a request is received from the guidance button at this time for the blind person to continue crossing the current intersection, then for P... Rz The subscript z indicates that when z is 1, if the azimuth is east to west and the guide button is left turn, then continue through the current intersection where the pedestrian phase of the traffic light is west-facing and north-facing (PH). 12 If the azimuth is south to north and the guide button is for right turn, then continue through the current intersection where the pedestrian phase of the traffic light is northbound (PH) and westbound (PH). 11 When z is 2, if the azimuth is west to east and the guide button is right turn, then continue through the current intersection. The pedestrian phase of the traffic light is east-facing (PH) and north-facing (PH). 22 If the azimuth is south to north and the guide button is left turn, then continue through the current intersection where the pedestrian phase of the traffic light is northbound (PH) and eastbound (PH). 21 When z is 3, if the azimuth is west to east and the guide button is left turn, then continue through the current intersection. The pedestrian phase of the traffic light is east-facing (PH) and south-facing (PH). 32 If the azimuth is north to south and the guide button is for right turn, then continue through the current intersection where the pedestrian phase of the traffic light is south (PH) and east to west (PH). 31 When z is 4, if the azimuth is east to west and the guide button is right turn, then continue through the current intersection. The pedestrian phase of the traffic light is westbound, and the pedestrian phase is southbound to northbound (PH). 42 If the azimuth is north to south and the guide button is left turn, then continue through the current intersection where the pedestrian phase of the traffic light is south (PH) and west to east (PH). 41 Then, the duration of the traffic light colors for the blind person to continue crossing the current intersection is calculated.

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