KR20010081493A - Apparatus for Collecting Traffic Information By Ultrasonic Means - Google Patents

Abstract

PURPOSE: An ultrasonic traffic volume detecting apparatus is provided to realize an interface circuit between a true time clock and a CPU board with providing a dial-up modem interface circuit so as to be capable of modem communication and directly connecting communication with a single series port provided from the CPU by utilizing the ultrasonic traffic volume detecting apparatus. CONSTITUTION: An ultrasonic sensor(11) periodically creates and outputs an ultrasonic transmitting signal and receives a reflected wave from cars or a ground. A signal processing unit(12) outputs a car detecting signal from the reflected wave received from the ultrasonic sensor. A CPU(13) creates a transportation data by using the car detecting signal from the signal processing unit. A memory unit stores the transportation data created by the CPU(13). A real time clock(16) provides a time information to the CPU(13) by creating a present time for the information of the transportation data. A modem(18) transmits The transportation data created by the CPU(13) and stored on the memory unit to center through a telephone line. A communication chip(17) changes the signal from the CPU(13) into an RS-232C standard which is communication agreement.

Description

Ultrasonic Traffic Detection Device {Apparatus for Collecting Traffic Information By Ultrasonic Means}

The present invention relates to an ultrasonic traffic detection apparatus, and in particular, to develop a real-time clock and the interface between the CPU to obtain time information from the CPU, and includes a dial-up modem interface circuit for a communication function, which is provided by the CPU. It features a single serial port to enable both modem and direct-connect communications.

The traffic detector is the lowermost part of the traffic management system and is the most basic element for constructing an urgent intelligent transportation system (ITS) to solve traffic congestion.

Vehicle detectors and traffic information collection equipment using ultrasonic sensors are non-embedded, and can be installed at a lower price than other equipments, and are easy to maintain because they are semi-permanent.

First, the principle of the ultrasonic traffic detection device will be described.

An ultrasonic sensor including a transmitter and a receiver is installed at a predetermined height from the road surface, periodically transmitting a transmission wave from the ultrasonic sensor, and detecting a reflected wave to detect the passage of the vehicle.

1 is a view for explaining the principle of the ultrasonic traffic detection device, Figure 1a is a case where the ultrasonic sensor is installed side, Figure 1b is a case where the ultrasonic sensor is installed in an overhead manner.

For example, when the ultrasonic sensor is installed at a height of 6m from the ground by the side mounting method, the time it takes for the transmission wave emitted from the ultrasonic sensor to reflect back from the vehicle is 44 kHz at the sound speed of 340 kHz. . If the vehicle is not in the sensor detection area, the transmitted wave is reflected off the road and blown away. When the ultrasonic sensor is installed in an overhead manner, the transmission period is determined based on the time of returning from the road. During the transmission period, as shown in Fig. 1, the gate signal is activated, and when the vehicle passes therebetween, the reflected wave by the passing vehicle is detected within a shorter time than the transmission period. That is, when the reflected wave is detected in the section in which the gate signal is activated, it means the passage of the vehicle.

Therefore, the ultrasonic traffic detection device includes an ultrasonic sensor which periodically generates and outputs an ultrasonic transmission signal and receives a reflected wave from a vehicle or the ground, an ultrasonic signal processor for outputting a vehicle detection signal from the reflected wave from the ultrasonic sensor, and an ultrasonic signal processor. And a CPU board for generating and storing necessary traffic data and statistical data using the output vehicle detection signal, and a modem for transmitting traffic data and statistical data generated and stored in the CPU board through a telephone line.

The present invention is to provide an interface method and a circuit between a real time clock and a CPU board when a real time clock is included in the ultrasonic traffic detection apparatus to generate traffic data according to time information.

The present invention also proposes a dial-up modem interface circuit to enable modem communication and direct connection communication to a single serial port provided by a CPU in an ultrasonic traffic detection device.

1 is a view for explaining the principle of the ultrasonic traffic detection device;

2 is a block diagram of an ultrasonic traffic detection device according to the present invention;

3 is an interface circuit diagram of a real time clock (RTC) and a CPU in the ultrasonic traffic detection apparatus according to the present invention shown in FIG.

4 is an example of address mapping of a real time clock;

FIG. 5 is a pinout diagram of a CPU serial port for modem control in the ultrasonic traffic detection apparatus according to the present invention shown in FIG.

6 is an interface diagram of a CPU, a communication chip, and a modem in the ultrasonic traffic detection apparatus according to the present invention shown in FIG.

Explanation of symbols on the main parts of the drawings

11: ultrasonic sensor 12: signal processor

13: CPU 14: ROM

15: RAM 16: Real Time Clock

17: communication chip 18: modem

In order to achieve the above object, the ultrasonic traffic detection device according to the present invention, the ultrasonic sensor periodically generating and outputting the ultrasonic transmission signal, and receiving the reflected wave from the vehicle or the ground; A signal processor for outputting a vehicle detection signal from the reflected wave received by the ultrasonic sensor; A CPU for generating traffic data using the vehicle detection signal from the signal processor; A memory unit for storing traffic data generated by the CPU; A real time clock generating a current time for providing time information of traffic data and providing time information to the CPU; A modem configured to transmit traffic data generated by the CPU and stored in the memory to a center via a telephone line; And a communication chip for converting a signal from the CPU into an RS-232C standard, which is a communication protocol.

Hereinafter, an ultrasonic traffic detection device according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of an ultrasonic traffic amount detecting device according to the present invention.

As shown in Fig. 2, in the ultrasonic traffic amount detecting apparatus according to the present invention, the ultrasonic sensor 11 periodically generates and outputs an ultrasonic transmission signal and receives reflected waves from a vehicle or the ground. The signal processor 12 outputs the vehicle detection signal from the reflected wave received by the ultrasonic sensor 11. The CPU 13 generates and stores traffic data and statistical data in the RAM 15 using the vehicle detection signal from the signal processing unit 12, and a system operation program is stored in the ROM 14. The real time clock 16 generates the current time to know the time when the vehicle passes on the road when generating the traffic data. The communication chip 17 converts the 0 to 5 V signal of the CPU 13 into the RS-232C standard, which is a communication protocol, for building a dial-up modem interface. The modem 18 connects the CPU 13 board and the center and transmits traffic data and statistical data stored in the RAM 15 to the center via a telephone line.

3 is an interface circuit diagram of a real time clock (RTC) and a CPU in the ultrasonic traffic detection apparatus according to the present invention shown in FIG.

Real Time Clock (RTC) is a chip that tells the current time. In general, it is connected to the bus of a system that requires time information such as a PC and plays a role of providing the current time of the system when calling the set address. In constructing the traffic data, since the time is an essential element, the ultrasonic traffic detection device according to the present invention also includes a real time clock.

In the present invention, the interface portion between the real-time clock chip and the CPU is designed using an FPGA or an ASIC. As shown in FIG. 3, the interface circuit between the real time clock and the CPU generates the chip select signal by logic implemented in the FPGA or the ASIC in the real time clock chip. The address to access the real time clock from the CPU is assigned 0x6000 address. In addition, by connecting the data bus of the real time clock and the input and output ports of the CPU to enable data transmission and reception between the CPU and the real time clock in a parallel manner. The current time information can be obtained from the CPU by reading address 0x6000 assigned to the real time clock.

When the address mapping of the real time clock is as shown in FIG. 4, in order to obtain time information through the real time clock, current time information can be obtained by reading desired data among the first 14 bytes of the real time clock. The time setting or correction or the oscillator on / off inside the real-time clock can be set by converting the register value, which is the lower 4 bytes, out of 14 bytes.

In the present invention, the real time clock not only operates by the internal power source but also stores the data stored in the internal 113 bytes of RAM even when there is no external power supply. Therefore, information such as the system ID number or the total vehicle count measured by the system can be safely stored in the RAM of the real-time clock even when the power is disconnected from the outside.

In the ultrasonic traffic detection device, the communication function is largely used for two purposes. First, it is used for the purpose of controlling the field equipment in the center. Specifically, the time set by the real time clock is matched with the time of various equipments and centers in the field to increase the reliability of the statistical data. Secondly, it is used to initialize and configure the field equipment during the field installation of the equipment. In each place where the ultrasonic traffic detection device according to the present invention is installed, the installation height, distance, etc. of the sensor may vary according to environmental constraints, and the ultrasonic sensors to be used may have some characteristic differences. Therefore, it is necessary to change the default value set in the system according to the environment of the site. For this purpose, it is necessary to have a communication function to set the default value by connecting the notebook and the system directly.

In the ultrasonic traffic detection apparatus according to the present invention, the communication chip used to construct the dial-up modem interface is a 'MAX232' chip. The MAX232 chip converts the 0-5 V signal output from the CPU into the RS-232C standard for communication protocols. In the MAX232 chip, TxD and RxD signals, which transmit and receive signals, are converted to the RS-232C standard, and these signals are transmitted and received along the telephone line with the sensor.

In the present invention, in order to implement the dial-up modem control logic, an interface between the modem, the communication chip (MAX232), and the CPU is implemented. The communication chip converts the CPU's 0V and 5V signals into RS-232 type signals or vice versa, allowing the CPU to control the dial-up modem.

FIG. 5 is a pinout diagram of a CPU serial port for modem control in the ultrasonic traffic detecting apparatus according to the present invention shown in FIG.

In FIG. 5, DTR and RTS are signals for checking whether a modem is ready to transmit and receive data, and DCD are signals for checking whether a modem of the system is connected to another modem. When two systems are connected by modem, data are transmitted and received using TxD and RxD signals. The CTS, DSR, RI, and GND signals are used to identify and ground other modems. The CPU identifies and controls each signal with its input and output ports, and uses serial port interrupts to recognize data transmission and reception.

FIG. 6 is an interface diagram of a CPU, a communication chip, and a modem in the ultrasonic traffic detecting apparatus according to the present invention shown in FIG.

In the ultrasonic traffic detection apparatus according to the present invention, the CPU 80C196 provides one serial port. Ultrasonic traffic detection devices must be connected to the field test computer when connected directly, as well as to an external dial-up modem for communication with the center. To this end, in the present invention, the dip switch is operated to serve two roles as one serial port. Specifically, the connection with the dial-up modem should be set to 38400bps, the baud rate of the CPU, according to the widely used standard of 57600bps modem. For this purpose, the baud rate is converted according to the state of the dip switch. When the state of the dip switch is input to the communication chip, the baud rate of the CPU is determined by logic implemented through the FPGA or the ASIC.

In the ultrasonic traffic detection apparatus according to the present invention, a function required for a single board is implemented using one 80196 CPU. That is, a single board performs ultrasonic sensor driving, received echo signal processing, traffic information collection, database generation, and communication. In order to properly perform these necessary functions, peripheral circuit design and system programming of the CPU board are required.

The CPU board design for performing each function is briefly described. The sensor drive signal is designed to control the drive time using the HSO (High Speed Output) signal of the CPU. In addition, the received signal is input to a high speed input (HSI) of the CPU to generate traffic information. The communication unit is integrated into a single board with an interface design between the CPU and the MAX232 communication chip. The above HSO / HSI and communication signals are all handled as interrupts, and the main route performs time acquisition, data generation and data storage functions.

As described above, the ultrasonic traffic detection apparatus according to the present invention presents an interface circuit between a real time clock and a CPU board when a real time clock is included to generate traffic data according to time information. In addition, a dial-up modem interface circuit is provided to enable modem communication and direct connection communication to a single serial port provided by the CPU.

Claims (7)

An ultrasonic sensor which periodically generates and outputs an ultrasonic transmission signal and receives reflected waves from a vehicle or the ground; A signal processor for outputting a vehicle detection signal from the reflected wave received by the ultrasonic sensor; A CPU for generating traffic data using the vehicle detection signal from the signal processor; A memory unit for storing traffic data generated by the CPU; A real time clock generating a current time for providing time information of traffic data and providing time information to the CPU; A modem configured to transmit traffic data generated by the CPU and stored in the memory to a center via a telephone line; And And a communication chip for converting a signal from the CPU into an RS-232C standard, which is a communication protocol. The method of claim 1, And the interface between the real time clock and the CPU generates the chip select signal of the real time clock chip by logic implemented in an FPGA or an ASIC using the CPU address signal. The method of claim 2, Ultrasonic traffic detection device characterized in that the data transmission and reception between the CPU and the real-time clock in parallel by connecting the data bus of the real-time clock and the input and output ports of the CPU. The method of claim 1, Some of the traffic volume data stored in the memory unit is redundantly stored in the RAM of the real-time clock. The method of claim 1, In pin assignment of the CPU serial port for the modem control, DTR, RTS is a signal to check whether the modem is ready to transmit and receive data, DCD is a signal to check whether the modem is connected to the modem of another system, and if two systems are connected to the modem, TxD, RxD signal Ultrasonic traffic detection device, characterized in that for transmitting and receiving data, CTS, DSR, RI, GND signals are used for the environment and ground of the modem. The method of claim 1, And the serial port of the CPU is connected to an external dial-up modem or directly to a field test computer for communication with a center using a dip switch. The method of claim 6, And a baud rate of the CPU is determined by logic implemented using an FPGA or an ASIC when the state of the dip switch is input to the communication chip.