International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056 Volume: 04 Issue: 01 | Jan -2017 www.irjet.net p-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 1015 Analysis of Obstacle Detection Using Ultrasonic Sensor Christofer N. Yalung 1 , Cid Mathew S. Adolfo 2 1 Military Technological College, Muscat, Oman 2 Military Technological College, Muscat, Oman ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract – Automation of the car braking system is an important feature in the development of the smart car. The ability of a smart car to detect and classify an obstruction that is in varying proximities from it play a vital role in the system’s design. In this study, EV3 Lego Mindstorm equipped with an ultrasonic sensor was used as a model of a large scale vehicle. EV3 Lego MIndstorm was programmed to slow down when it is at a certain distance from the obstruction, and to stop when it is 15 cm away from the obstruction. There were five obstructions: wood, paper, cloth, plastic and metal. The distance measurement of the ultrasonic sensor and the Neural Network was used for the classification of the obstruction and Multiple Correlation was used for obstacle detection. There were 250 samples taken from the distance measurements of five different types of obstruction, each with a different cross sectional area, and a total recording time of 8 seconds. Overall, there is a high correlation coefficient in the distance measurement of the different types of obstruction materials. It is concluded that the ultrasonic sensor was able to detect the five given types of obstruction. Classification performance was very poor, which means that on the basis of distance measurement, the ultrasonic sensor cannot effectively classify the types of obstructions. Key Words: Ultrasonic Sensor, Obstacle detection, Artificial neural network, Distance measurement 1.INTRODUCTION Nowadays, automation in technology is widespread, this can be seen on doors, electronic devices, cars and in various industrial applications. This is made possible by sensing devices, which serve as a medium between the machine and the environment. Ultrasonic sensor is an incredibly useful sensor in the field of automation. For example, a mobile robot receives environmental information, converts it into a signal and performs this signalled task like avoiding obstacles (In this sentence you should mention specifically the function of the ultrasonic sensor). This particular type of sensor produces satisfactory results and is cost effective. The algorithm for distance calculation is based on the measurement of the time of flight of the ultrasonic waves. The distance between two objects can be measured using the ultrasonic sensor. The technique of distance measurement is based on the measurement of the elapsed time between the emission of the wave and the reception of the echo. The propagation of the ultrasonic wave is done at the sound speed in the air (340 m/sec). A typical ultrasonic distance sensor consists of two main elements. One element produces sound, another catches reflected echo. Basically, these pieces are a speaker and a microphone. The device generates ultrasonic impulses and triggers the timer. The other element registers the arrival of the sound impulse and stops the timer. From this information it is possible to calculate the distance travelled by the sound. It is usually not difficult to select a sensor that suits the environmental and mechanical requirements of a particular application, or to evaluate the electronic features available with different models. Still, many users may not be aware of the acoustic subtleties that can have major effects on the operation of the ultrasonic sensor and the measurements being made with them [1]. The basic principle of sound propagation, the effect of a wave when it strikes a solid object and the reception of the reflected sound waves are illustrated in Fig-1[2]. Fig-1: Ultrasonic sensor operations The velocity of the sound in air is given by the equation (1), this is used to calculate the speed of the sound in air. The distance that sound travels is equal to the speed of sound in the medium multiplied by the time that sound travels[2]. (1) The impulse width is proportional to the time required for the echo return. This time is called time-of-flight (TOF) [3]. But there are other factors which may also affect the propagation of sounds such as: ambient pressure, gas density and humidity [4].