CAREER EPISODE – 2INTRODUCTIONCE 1.
1This career episode summarizes the details of the project conducted by me in my pre-final year. Chronology : VII semester (January 2013 to April 2013)Name of the Organization : St.Joseph’s College of EngineeringGeographical Location : ChennaiProject Title : Real Time Implementation of ARM based Automatic Intelligent braking system . BACKGROUNDCE 1.
2During the seventh semester of my Electronics and Instrumentation course, I attended a seminar where one of the speakers was describing how we could use automatic braking system in cars to prevent accidents. Later I did an extensive research on the topic and found a few papers in IEEE which already proposed this idea. I was intrigued by this whole concept as this could be a major breakthrough in India where road accidents are pretty common. My friend and I, the two of us decided to do a real time implementation of this automatic braking system. When I discussed regarding this with one of my faculties, he was ready to provide me with any assistance I would need.
I had completed a subject, embedded system, in an earlier semester. I was excited to use that knowledge to do this implementation.Aim ; ObjectiveCE 1.3The main aim of the project was to implement the extensive theoretical knowledge that I had gained during the research on automatic braking system and embedded systems.The objective of this project was just not to propose but also to implement a system by which unnecessary collisions of vehicles, accidents due to inattentive driving, sleep-deprived driving as such can be avoided.Roles and ResponsibilitiesCE 1.4To understand the working and construction of a basic embedded system.
To understand how to integrate and work with various hardware and software tools require to device an embedded system.To understand and meet the growing technologies in embedded system.To study and use the ultrasonic sensor.
To work in proper co-ordination with my team member and project guide to meet the various deadlines throughout the project period.PERSONAL ENGINEERING ACTIVITY CE 1.5In order to implement this automatic braking system, I had to brush my basics on embedded system, different types of sensors, microcontrollers. In my sixth semester we had a practical lab in embedded system, so all that knowledge was going to be used for this project. I made a study on how automotive safety devices had improved over the years. It definitely proved to be a growing field. It started with individual devices like seat belts, air bags, knee bolsters.
Later came the preventive measures like improving visibility with headlights, use of wind shield, tire tractions. And at that moment we were in the middle of development and inventions in order to avoid collisions and providing maximum protection using pre-crash sensing, sensors etc.Proposed systemC.
E 1.6Our proposed system was based on pre-crash sensing. The idea was to use an ultrasonic sensor to sense the object in front of the vehicle.
It will sense both stationary and moving objects. The sensor also calculates the distance between the vehicle and the obstacle. If the driver slows down and the distance is maintained between the vehicle and object then there is no problem. On the other hand, if he does not apply the brakes and proceeds at the same speed, he comes to a point where the distance of the obstacle equals the braking distance. This is the last chance for the driver to apply the brake and slow down the vehicle. If he still goes at the same speed, the microcontroller in the system will activate the brakes and avoid a collision by bringing the vehicle to a stop. Normally, one would not stop at a point when the vehicle is touching the obstacle; some distance is left before the obstacle. The distance is also accounted for by the microcontroller.
Hardware componentsC.E 1.7In order to design this system, I did an in-depth research on all available microprocessors and microcontrollers. After the study, I decided to use the ARM processor for building this system. It is a family of CPU which is based on RISC. RISC means reduced instruction set computers.
This processor was chosen mainly for its low power consumption. For my project we specifically used LPC 2148 PCB which is based on ARM7TDMI-S CPU, this supports virtual memory system. Next I chose the ultrasonic distance sensor to sense the obstacles in front and also to calculate their distance. The ultrasonic distance sensor has two openings, one act as the transmitter and the other as receiver. Ultrasonic waves of 40 KHz frequency will be sent from the transmitter of the sensor. The ultrasonic waves have the property that they are not affected by environmental changes. When the waves come in contact with an obstacle, the ultrasonic wave will be reflected back from the obstacle.
An ultrasonic receiver present in the same sensor receives these waves after reflection. The time gap between the transmission and receiving of the ultrasonic waves gives the distance of the obstacle from the vehicle.GPS ; Proximity SensorC.E 1.8I wanted to include the Global Positioning System technology into our project.
I had recently learnt about the GPS system’s uses and advantages. I wanted to incorporate the same somehow in my project. So I suggested that, in case of a collision we locate the position of the car and alert family members of the accident location through SMS.
In order to measure the speed at which the vehicle is travelling and to calculate if the vehicle will collide at the travelling speed, I used ADXL335 accelerometer. It can measure both static and dynamic acceleration. It is a complete 3 axis acceleration measuring system. The accelerometer consists of differential capacitor that consists of independent fixed plates and plates attached to the moving mass. Acceleration deflects the moving mass and unbalances the differential capacitor resulting in a sensor output whose amplitude is proportional to acceleration. Phase-sensitive demodulation techniques are then used to determine the magnitude and direction of the acceleration. Finally I used a inductive proximity sensor.
It is majorly used for non-contact detection of objects. I learnt that it emits an electromagnetic field and compare it with the received field. The variation in the transmitted and received field will denote how close the obstacle is to the vehicle.Programming the systemC.E 1.9In order to program the whole embedded system, I used IAR embedded workbench. I chose this embedded IDE because I had learnt and used it earlier during my practical lab sessions in the sixth semester. It provides a completely integrated development environment including a project manager, editor, build tools and debugger.
IAR embedded Workbench for ARM provides extensive support for a wide range of ARM devices and generates very compact and efficient code. Next step was to program the controller. There are several methods which can be used to program the on-chip flash.
The easiest is by the built-in boot loader which allows user code to be downloaded via UART0 to the RAM & then be programmed into the flash. The In-system programming (ISP) is performed without removing the microcontroller from the system. The in-system programming facilitates remote programming of the ARM through the serial port (RS232).
Difficulties and challengesC.E 1.10I was finally able to do a complete implementation of the project idea though I had to face a few difficulties. Once we had everything set up , during the testing we found that our robotic vehicle model always stopped after coming in contact with the obstacle instead of maintaining the minimum distance criteria. I figured out that we had programmed the condition wrongly and I quickly fixed it.
The other issue we had was that we couldn’t send the alert message to multiple phone numbers but was able to successfully send to one number. We let this be a drawback, so that we could learn more on reusing frequencies to enable this. Thus we proposed this could be an improvement to our project.SUMMARYC.E 1.11This project facilitated me to implement my knowledge on Embedded system and various types of sensors in real time.This project helped me to think of possible engineering solutions for everyday problems we face in our life rather than complaining about them.Working on this project also helped me to improve my knowledge on current growing technologies like automation , GPS , GSM.In order to implement this project I spent a lot of time reading various papers submitted in IEEE which eventually gave me an exposure to new budding technologies.In this project course, I also learned to organize and coordinate with my team member and also to handle unanticipated issues.