Obstacle Avoidance Robotic Vehicle Using Ultrasonic Sensor

Introduction:

Now day’s many industries are using robots due to their high level of performance and reliability and which is a great help for human beings. The obstacle avoidance robotics is used for detecting obstacles and avoiding the collision. This is an autonomous robot. The design of obstacle avoidance robot requires the integration of many sensors according to their task.

The obstacle detection is primary requirement of this autonomous robot. The robot gets the information from surrounding area through mounted sensors on the robot. Some sensing devices used for obstacle detection like bump sensor, infrared sensor, ultrasonic sensor etc. Ultrasonic sensor is most suitable for obstacle detection and it is of low cost and has high ranging capability.

Working Principle:

The obstacle avoidance robotic vehicle uses ultrasonic sensors for its movements. A microcontroller of 8051 family is used to achieve the desired operation. The motors are connected through motor driver IC to microcontroller. The ultrasonic sensor is attached in front of the robot.

Whenever the robot is going on the desired path the ultrasonic sensor transmits the ultrasonic waves continuously from its sensor head. Whenever an obstacle comes ahead of it the ultrasonic waves are reflected back from an object and that information is passed to the microcontroller. The microcontroller controls the motors left, right, back, front, based on ultrasonic signals. In order to control the speed of each motor pulse width modulation is used (PWM).

Different Sensors used for obstacle avoidance Robotic vehicle

1. Obstacle detection (IR sensor):

The IR sensors are used for obstacle detection .The sensor output signal send to the microcontroller. The microcontroller controls the vehicle (forward/back/stop) by using the DC motor which is placed in vehicle. If any obstacle placed in line the IR sensor fails to receive the light rays and gives signals to the microcontroller. The microcontroller will stop the vehicle immediately and siren will on. After one minute the robot will be check the path status, if obstacle is removed the robot move far word else the robot will return back to move starting place. The sensor detects objects by emitting a short ultrasonic burst and then listening for the eco. Under control of a host microcontroller, the sensor emits a short 40 KHz explosion. This explosion ventures or travels through the air, hits an article and after that bounces once again to the sensor. The sensor provides an output pulse to the host that will terminate when the echo is detected; hence the width of one pulse to the next is taken into calculation by a program to provide result in distance of the object.

2. Path detection (proximity sensor):

The normal case both sensors giving the guidelines and robot follows it going straight on path.  When the line is end at that time the robot reverse at 180 and turns back the same place.

The proximity sensors are used for path detection. When the right sensor is not detected the curve line, the microcontroller activates the left motor to turn left until the signal from right sensor. Once signal is detected right sensor, the two motors are activated to go forward. When the line is end at that time the robot reverse at 180 and turns back the same place.

3. Ultrasonic Sensor:

The ultrasonic sensor is used for obstacle detection. Ultrasonic sensor transmits the ultrasonic waves from its sensor head and again receives the ultrasonic waves reflected from an object.

There are many applications use ultrasonic sensors like instruction alarm systems, automatic door openers etc. The ultrasonic sensor is very compact and has a very high performance.

Working Principle:

The ultrasonic sensor emits the short and high frequency signal. These propagate in the air at the velocity of sound. If they hit any object, then they reflect back echo signal to the sensor. The ultrasonic sensor consists of a multi vibrator, fixed to the base. The multi vibrator is combination of a resonator and vibrator. The resonator delivers ultrasonic wave generated by the vibration.  The ultrasonic sensor actually consists of two parts; the emitter which produces a 40 kHz sound wave and detector detects 40 kHz sound wave and sends electrical signal back to the microcontroller.

The ultrasonic sensor enables the robot to virtually see and recognize object, avoid obstacles, measure distance. The operating range of ultrasonic sensor is 10 cm to 30 cm.

Operation of the ultrasonic sensor:

When an electrical pulse of high voltage is applied to the ultrasonic transducer it vibrates across a specific spectrum of frequencies and generates a burst of sound waves. Whenever any obstacle comes ahead of the ultrasonic sensor the sound waves will reflect back in the form of echo and generates an electric pulse. It calculates the time taken between sending sound waves and receiving echo. The echo patterns will be compared with the patterns of sound waves to determine detected signal’s condition.

Note: The ultrasonic receiver shall detect signal from the ultrasonic transmitter while the transmit waves hit on the object. The combination of these two sensors will allow the robot to detect the object in its path. The ultrasonic sensor is attached in front of the robot and that sensor will also help the robot navigate through the hall of any building.

Applications of Ultrasonic Sensor:

• Automatic change over’s of traffic signals
• Intruder alarm system
• Counting instruments access switches parking meters
• Back sonar of automobiles

Features of Ultrasonic Sensor:

• Compact and light weight
• High sensitivity and high pressure

• High reliability
• Power consumption of 20mA

• Pulse in/out communication
• Narrow acceptance angle
• Provides exact, non-contact separation estimations within 2cm to 3m
• The explosion point LED shows estimations in advancement
• 3-pin header makes it simple to connect utilizing a servo development link

Applications of Obstacle Avoidance Robotic Vehicle:

• Especially military applications
• It can be used for city wars

Now clearly got an idea about the concept of the robotic vehicle using ultrasonic sensor of obstacle detection if any furthermore queries on this topic or on the concept of the electrical and electronic projects leave the comments bellow.

Photo Credit:

• Ultrasonic Sensor General Diagram by Letsmakerobots
• Ultrasonic Sensor Working Principle by Microsonic

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