CN102568232B - System for prewarning vehicle speed on bent roads based on radio frequency identification (RFID) - Google Patents

Abstract

The invention discloses an RFID-based curve speed warning system, which includes a vehicle-mounted unit and a road-based unit. The vehicle-mounted unit includes a CAN bus, a digital tube, a buzzer, a control chip, and an RFID reader. The RFID tag of information, the CAN bus access control chip, the control chip is connected with the nixie tube, the buzzer, the RFID reader is connected with the control chip bidirectionally, and the RFID reader communicates with the RFID tag. The curve speed warning system of the present invention can Before the vehicle enters the curve, it reads the curve information stored in the road RFID tag, and if there is a safety hazard, it will call the police in advance, which can significantly reduce the accident rate, especially suitable for urban multi-segment continuous curved roads and expressways.

Description

An RFID-based curve speed warning system

technical field

The invention relates to the field of intelligent transportation, in particular to an RFID-based curve speed warning system.

Background technique

Excessive speed of the car when entering the curve will cause sideslip or rollover. Research on the speed warning mechanism of the curve has been carried out at home and abroad. The current main solution is to rely on GPS and high-precision electronic maps, such as the patent number 200410081844 The .X navigation system's curve safety warning and driving record method can be combined with electronic maps to give early warning before entering a curve, but the effectiveness of GPS signals is easily affected in areas with many curves such as bridges and dense buildings, and it also needs to follow the road Update the high-precision electronic map in time; the patent No. 200910158546.9 is the dynamic detection method and early warning device for the anti-rollover of trucks on curves, which can only sense the slope of the lane and the lateral acceleration of the vehicle after the vehicle has completely entered the curve, and cannot be advanced. Early warning; at the same time, more sensors need to be installed, which is not conducive to cost control.

Contents of the invention

The technical problem to be solved by the present invention is to provide an RFID-based curve speed early warning system to provide early warning for cars at high speeds on curved roads to prevent traffic accidents such as sideslips and rollovers. .

In order to solve the above-mentioned technical problems, the technical solution adopted in the present invention is: an RFID-based curved road speed warning system, including a vehicle-mounted unit and a roadbed unit, and the vehicle-mounted unit includes a CAN bus, a nixie tube, a buzzer, a control chip, an RFID The reader, the subgrade unit includes an RFID tag that stores curve data information, the CAN bus is connected to the control chip, the control chip is connected to the digital tube and the buzzer, the RFID reader is connected to the control chip in two directions, and the RFID reader communicates with the RFID tag .

The control chip can be various microprocessors such as single-chip microcomputer, ARM, DSP.

The digital tube is an LED digital tube.

The curve speed warning system of the present invention can read the curve information stored in the road RFID tag before the vehicle enters the curve, and if there is a potential safety hazard, it will give an alarm in advance, which can significantly reduce the incidence of accidents, and is especially suitable for multi-segment continuous curves in cities roads and highways etc.

Description of drawings

Fig. 1 is a structural block diagram of an RFID-based curve speed warning system according to an embodiment of the present invention;

Fig. 2 is a flow chart of a method for the curve speed warning system of an embodiment of the present invention to perform curve warning;

Fig. 3 is a circuit schematic diagram of the STC89C52 single-chip microcomputer control chip according to an embodiment of the present invention.

Detailed ways

As shown in Figure 1, an embodiment of the present invention includes a vehicle-mounted unit and a road-based unit, the vehicle-mounted unit includes a CAN bus, a nixie tube, a buzzer, a control chip, and an RFID reader, and the road-based unit includes an RFID tag that stores curve data information , the CAN bus is connected to the control chip, the control chip is connected to the digital tube and the buzzer, the RFID reader is connected to the control chip in two directions, and the RFID reader communicates with the RFID tag.

The on-board unit controls the RFID reader through the RS232 serial port or SPI interface, etc., so that it sends out electromagnetic waves for reading RFID tags. After receiving the electromagnetic waves, the RFID tags in the roadbed unit activate and send built-in front curve data to the RFID reader. After obtaining the curve data ahead, the control chip detects the wiper switch signal according to the tire adhesion coefficient of the road ahead and the quasi-static rollover principle of a rigid car, and calls the recommended tire adhesion coefficient under different weather conditions. The safe vehicle speed threshold V _S when the vehicle is skidding can be calculated through the tire adhesion coefficient, curve curvature, super height and other curve parameters, and the speed value is displayed in the LED digital light tube. When it is detected that the vehicle speed on the CAN bus is greater than the safe vehicle speed threshold, a graded warning will be given through the buzzer according to the current vehicle speed V and the distance from the entrance of the curve. The graded early warning is judged according to the vehicle deceleration value required to enter the curve. When the required deceleration value a is less than the comfortable deceleration threshold (such as 2.5m/s ² ), the general warning is activated; when it is greater than the comfortable deceleration threshold (such as 2.5m /s ² ), the emergency warning is activated.

The information contained in the RFID tag in the subgrade unit includes: the distance D between the current RFID tag and the entrance of the curve ahead, the superelevation of the curve The maximum curvature ρ of the curve, the tire adhesion coefficient μ ₁ in normal weather, the tire adhesion coefficient μ ₂ in rainy weather, etc.

Curve safe speed threshold Among them, the recommended adhesion coefficient μ of the tire is μ ₁ or μ ₂ . When the wiper on signal is not detected on the CAN bus, μ ₁ is the recommended tire adhesion coefficient; otherwise, μ ₂ is used, and g is the acceleration of gravity.

deceleration required for braking Among them, V is the current speed of the vehicle from the CAN bus, Vs is the safe speed threshold, and t is the reaction time before the driver brakes, which is generally 0.75 to 1 second.

General value range: g is 9.8m/ ^s2 ; the distance D between the label and the entrance of the curve ahead is 100-200m; the maximum curvature ρ of the road curve is 0.0005/m-0.00272/m; normal The recommended adhesion coefficient μ ₁ for tires in weather is 0.75-0.9, the recommended adhesion coefficient μ ₂ for tires in rainy weather is 0.5-0.7, and the comfortable deceleration is generally 1.5m/s ² ～2.5m/s ² .

The flow chart of the curve warning system in an embodiment of the present invention for the curve warning system is shown in FIG. 2 .

In this embodiment, the control chip adopts STC89C52 single-chip microcomputer, and its circuit schematic diagram is shown in Fig. 3 .

Claims (3)

1. the bend vehicle speed prewarning system based on RFID, comprises board units and roadbed unit, it is characterized in that, board units comprises CAN bus for transmitting vehicle present speed, the safe speed threshold value when showing defective steering stabilizer charactron, hummer, the safe speed threshold value when calculating defective steering stabilizer and control control chip, the RFID reader of hummer grading forewarning system, roadbed unit comprises the RFID label that stores bend data message, CAN bus Access Control chip, control chip is connected with charactron, hummer, RFID reader is connected with control chip is two-way, RFID reader and RFID label communication; Described bend data message comprises the distance D of current RFID label and curve ahead porch, bend superelevation amount , bend maximum curvature , tire adhesion coefficient under normal weather , tire adhesion coefficient under rainy weather ; Described safe speed threshold value , when rain brush not detected opening signal in CAN bus, get ; Otherwise get ; for acceleration of gravity; The car deceleration degree value required according to bend judges described grading forewarning system: when the required deceleration value of braking while being less than comfortable retarded velocity threshold value, start general early warning; When the required deceleration value of braking while being greater than comfortable retarded velocity threshold value, start urgent early warning; Wherein brake required deceleration value , wherein t for driver brakes the front reaction time, t span is 0.75～1 second.

2. the bend vehicle speed prewarning system based on RFID according to claim 1, is characterized in that, described control chip is STC89C52 single-chip microcomputer.

3. the bend vehicle speed prewarning system based on RFID according to claim 1, is characterized in that, described charactron is LED charactron.