Multipoint wireless data acquition system for vehicles-- Circuit Description --3

·         Flex sensor is an unique and sensitive component of car black box which changes resistance on bending. It changes its resistance when the sensor is press due to force and this sensor will embedded in car paint. And this sensor is connected to controller through ADC.

·         In this system LM35 temperature sensor is use to record temperature of vehicle i.e. cabin temperature and engine temperature and it is also connected to controller through ADC. And its output voltage is linearly proportional to Celsius.

·         The 3 axis sensor i.e. Accelerometer which is use to sense tilting of car or vehicle. It senses the current position of that system by taking its X-axis, Y-axis and Z-axis coordinates. This sensor connected to ADC which will connect the sensor to microcontroller.

·         The values which are sensed by the all parameters are displayed on LCD. And for that 16 x 2 alphanumeric LCD is use. The LCD can be mounted on dash board of car which will be more convenient for driver of the car.   

·           All these above sensors are at same priority level when this sensor goes above fix threshold microcontroller starts operating means it sends message via GSM transmitter.

·                                   Microcontroller Needs +5V DC for its operation so 230V AC is stepped down to 9V AC, then rectified using four 1N4007 diodes (connected in full wave bridge rectifier configuration). Then this DC as it is pulsating need to be smoothened, so a large value electrolytic capacitor is used for filtering. LM7805 (+5V voltage regulator) is used to provide constant +5V DC even if we have voltage fluctuation in 230V AC

·         This system should be mounted in one  box which should be tough and compact as possible as for the protection of all above sensors and it should be easily fixed in car.

Multipoint wireless data acquition system for vehicles-- Circuit Description --2

·         These all above components are monitor and controlled by microcontroller.

·         The controller use in this system is of 40 pins and it has 4k bytes of ISP i.e. (In System Programmable) flash memory and its operating range is 4.0v-5.5v and consist of 128 x 8 internal memory.

·         The components which are installed in box are not directly connected to controller because the output of components is analog in nature and controller accept only digital so for that purpose ADC is use which converts analog input into digital output.

·         Temperature sensor’s output, flex sensor’s output and accelerometer’s output is given to ADC as inputs.

·         Digital equivalents of these inputs from ADC’s output are given to microcontroller as inputs.

·         GSM stands for Global System for Mobile. It is a module which is use to send messages regarding to car temperature or any damage to car or it has met to accident. And it is connected to TX pin of controller.

·         In this system GPS is use for locating and tracking the location of vehicle. It also calculate the geographical position of module. And GPS is connected to RX pin of controller

Multipoint wireless data acquition system for vehicles-- Circuit Description --1

 Circuit Description

 

·         Actually the concept of car black box is that the data is sent via GSM to the car owner or relative in form of SMS when an accident is happen. So to monitor this process various components are required and so they are installed in black box .The components installed in box are as follows:

1. Microcontroller ( 89C51)

2. Temperature sensor (LM35)

3. Flex sensor

4. Accelerometer

5. LCD (16x2 alphanumeric display)

6. ADC (0808)

Multipoint wireless data acquition system for vehicles.-- Circuit Diagram

                  CIRCUIT DIAGRAM

Multipoint wireless data acquition system for vehicles--Explanation continued..

7. Flex Sensor

                          It is a unique component that changes resistance when bent. An un-flexed sensor has a nominal resistance of 10,000 ohms (10 K). As the flex sensor is bent in either direction the resistance gradually decreases.
Sensor is also pressure sensitive, and may be used as a force or pressure sensor
The flex sensor operating temperature is -45F to 125F.

8. Accelerometer

                            This is basically a 3 axis sensor which will be able to sense the tilting of the car or vehicle. The ADXL335 is a small, thin, low power, complete 3-axis accelerometer with

signal conditioned voltage outputs. It Basically consists of a 3-Axis Sensor which can sense the postion of that current circuit, taking out its x-axis y-axis and z-axis co-ordinates.Acciendent of a car is not always said to be happened if the car is banged but it might happen that the car is tilted or went completely upside down.so for that reason this Sensor is used.

9. GPS
    

   In this project GPS is used for locating and tracking the vehicle. The GPS module calculates the geographical position of the module. This helps in detecting the location/position of the module. G-Mouse is a total solution GPS receiver, designed based on the most high sensitivity first GPS kernel architecture. This positioning application meets strict needs such as car navigation, mapping, surveying, security, agriculture and so on. Only clear view of sky and certain power supply are necessary to the unit. It communicates with other electronic utilities via compatible dual-channel through RS-232 or TTL and saves critical satellite data by built-in backup memory. With low power consumption, the G-Mouse tracks up to 8 satellites at a time, re-acquires satellite signal in 1 sec and updates position data recovery second.4 power-saving mode allows the unit with ultra-low power request.

Multipoint wireless data acquition system for vehicles--Explanation continued....

6. GSM in This Project:

         

In this project GSM module is used to send the messages containing the accident information along with the latitude and longitude position of module at the time of accident. For that we use an ordinary GSM mobile hand set. The GSM can be controlled by certain commands called AT commands. Through our software we control the GSM modem to generate and transmit the text messages on to another GSM modem in the program.

Example for the AT command are,
AT: -Sends to the module for detecting the proper working of the module.
AT+CMGF=1:-Command for shifting module in to text mode.
AT+CMGS=”+91.............”-Command for connecting to another module.
After sending the AT the module will return an OK message to show the proper functioning of the module. Then the commandAT+CMGF=1 shifts the module to the text mode. The module now returns”>”. Then AT+CMGS=”+91********** If “>” is received from the GSM module, type the SMS data and give Ctrl+Z. This will send the SMS.

Multipoint wireless data acquition system for vehicles--Explanation Continued...

3. ADC0808:-

                             
The ADC0808, ADC0809 data acquisition component is a monolithic CMOS device with an 8-bit analog-to-digital converter, 8-channel multiplexer and microprocessor compatible control logic. The 8-bit A/D converter uses successive approximation as the conversion technique. The converter features a high impedance chopper stabilized

comparator, a 256R voltage divider with analog switch tree and a successive approximation register. The 8-channel multiplexer can directly access any of 8-single-ended analog signals.

4. Temp. Sensor (LM35): 

The LM35 series are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade) temperature. The LM35 thus has an advantage over linear temperature sensors calibrated in ° Kelvin, as the user is not required to subtract a large constant voltage from its output to obtain convenient Centigrade scaling.
Specifications
Supply Voltage (Min) (V) -4
Supply Voltage (Max) (V) -30
Iq (Type) (uA) -56
Sensor Type -Analog
Operating Temperature Range (C) =-55 to 150

Multipoint wireless data acquition system for vehicles(Car Black Box using 8051)--Block diagram and explanation of each blocks

                                                                                                                        Block Diagram

Explanation of Each Block:

1. Power supply:

                          Microcontroller Needs +5V DC for its operation so 230V AC is stepped down to 9V AC, then rectified using four 1N4007 diodes (connected in full wave bridge rectifier configuration). Then this DC as it is pulsating need to be smoothened, so a large value electrolytic capacitor is used for filtering. LM7805 (+5V voltage regulator) is used to provide constant +5V DC even if we have voltage fluctuation in 230V AC

2. Microcontroller:

                          We are using 8051 microcontroller.  It has a 8 bit CPU for operation of data. It has low power RISC based architecture. It is available in 40 pin DIP package. The AT89S51 is a low-power, high-performance CMOS 8-bit microcontroller with 4K bytes of in-system programmable Flash memory.

The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry standard 80C51 instruction allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with in-system programmable Flash on a monolithic chip, the Atmel AT89S51 is a powerful microcontroller which provides a highly-flexible and cost-effective solution to many embedded control applications. The AT89S51 provides the following standard features: 4K bytes of Flash, 128 bytes of  RAM, 32 I/O lines, Watchdog timer, two data pointers, two 16-bit timer/counters, a five vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In addition, the AT89S51 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes.

Need of Multipoint Wireless Data Acquisition System for Vehicles

           Need of Multipoint Wireless Data Acquisition System for Vehicles

 

Just like “black boxes” help determine the cause of an airplane accident, car black boxes help determine what has caused a car accident and the events that led to collision. They are particularly valuable when no witnesses are present at the scene of the accident and when each driver has his/her own version of the events. The benefits of car black boxes for reconstruction of the events before accident are also emphasized by accident investigators, the police and increasing number of insurance companies which now have a powerful tool to determine whether the claim is justified or not.

The data from the car black box is a reliable record of the driver’s actions few seconds before the accident and is an important piece of evidence when there are no witnesses of the accident or/and the drivers are blaming each other for causing the collision. However, car accident investigators do not rely on the records of car black boxes alone just like airplane crash investigators also collect the fragments of the airplane before they start to search for potential causes and explanations of the crash. Car accident investigators also look at the physical evidence as well as try to find all the witnesses and individuals involved in the accident. In fact, they check the data from the black box only when the traditional way of reconstruction of the events is not possible or incomplete for one reason or the other.

Unlike plane crashes, car accidents are not that difficult to solve because a collision leaves a series of evidence that point out to the cause of accident as well as who or what has caused it. In addition, there is usually at least one witness of the event other than the people involved in the accident. In most cases, accident investigators do not need the data from the car black box but the small device has helped solve a number of difficult cases and has been also used as evidence in the courts.

I will shortly be posting the entire project and the circuit diagram with the datasheets and please feel free to comment your feedback will be greatly appreciated .

Multipoint wireless data acquition system for vehicles(Car Black Box using 8051)--Introduction

                                                     Introduction

In the present day everyone are running behind speed all want to come first. In such sceneries accident are increasing. Daily many new vehicles are being added on the road. This also increases the amount of accident. There won’t be a day on which there is no death due to road accident? Many rules are being enforced to reduce accidents but none of them have been able to stop them, but they are only able to decrease them to an extent. The highway safety association in Europe, America and China has been planning to implement some devices into vehicles which would safeguard the interest of the passengers. Several automobile manufacturers like General Motors, Toyota, Volks Wagen, Tata Motors have initiated many research and developmental activities in this regard. The vehicles are fitted with airbags, anti-lock breaking system and many such things. But in order to do any research or development there is a need for the knowledge of the real cause of the accident. The accident may occur due to the mistake of others or the problems in the working of the vehicle such as break failure, driver’s negligence or any other problem. So any such system will gather/record information for research related operations.

We already have Black Boxes fitted on aircrafts, but such system are very costly and can only be afforded for airplanes but it will be even costlier than even the costliest super cars itself. So there is no way that so expensive device can be used on a regular car. So we are designing a low cost system that will record the engine parameters like engine temperature, fuel tank level, ADXL335 accelerometer to monitor the tilt or whether the vehicle has met any accident. It will send these data to the owner of the vehicle or relatives of the driver via GSM in the form of SMS. In case of accident system will send message to pre stored number and help can immediately be provided without delay.

So we made an initiative to design a data logger as an emergency alert system. This initiative was made because of delayed medical help and relief. We also kept in mind as to decrease the cost so as to make it affordable o vehicle of all ranges. Our system can be also further expanded by adding up many more sensors such as vibration sensors, gas sensors.

Car Black Box using 8051

Hello everybody !
  My name is Rutvij Pathak .I am a aspiring engineer from India . I recently completed my pre - engineering diploma . For our final year in diploma we had to create a project . Me and my friends chose to do a project named " Multipoint data acquisition system for vehicles . Now its all a fancy name but in essence it is a 'Black Box ' designed for car or vehicles in general .


 

ABSTRACT

Multipoint wireless data acquisition system for vehicles is system developed for vehicles, which notifies a predetermined user in an event of collision of the car. Predetermined user is notified through GSM system via SMS.SMS sent to the user contains various vital statistics regarding the temperature of the car and its GPS location at the present time. LCD display is used to display various sensor values.

The vehicles are constantly monitored with help of various sensors. Sensors used are accelerometer, Temperature sensor and Flex sensor. Accelerometer is used to determine the orientation of the car at a given time. Temperature sensor is used to record the temperature of the vehicle i.e. cabin temperature, engine bay temperature etc. Flex sensor is used to determine if an actual collision has happened i.e. if the vehicle has crashed into something.

All these above sensors are on the same priority level i.e. if any of the above sensors goes above a certain threshold; the microcontroller sends a message via GSM transmitter.

LCD display (16X2 alphanumeric displays) is used to display various sensor values.