CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND OF STUDY
Over the years the curiosity of man and his intellectual prowess has led him to the discovery and invention of tools and machines that some only envisioned as impossible. In an attempt to make life easier and more comfortable he has delved into endless studies and researches to validate his unthinkable ideas, and one of the results of his intellectual power is the creation of autonomous self-controlling machines and devices. Robotics is a science of modern technology in which machine systems are programmed for general use. Obstacle detection and avoidance been an aspect of robotics, it involves the task of carrying out some preprogrammed objective which is subject to non-collision position constraints. The growing need of unmanned aerial and ground vehicles especially for military surveillance and city wars, has made the concept of obstacle avoidance a much desired one.
The obstacle detector robotic vehicle is designed to navigate without any sort of external influence through an unknown environment by avoiding collisions. However, it is worthy of note that the concept of obstacle avoidance differs considerably from path planning, this is considered so because the former is usually implemented using the reactive control law while the latter involves the pre-computation of an obstacle-free path in which the robot is programmed to navigate through. The need for such a system cuts across almost every sector of society. In 1988 a mobile nursing robot system was proposed, it was designed as an aid to bedridden patients who acquire constant assistance for the most elementary need. Such a devise was hoped to return a measure of independence to bedridden patients and also reduce the number of people who need hospitalization and constant attendance. (Borenstein and Koren, 1988).
The concept of obstacle detection and avoidance works essentially with the aid of robotic sensors. These sensors provide the means for the robot to detect information about its self and its environment. A single sensor integrated into an obstacle detector robotic vehicle is sufficient to navigate the system through its environment, although increasing the number and variety of sensors can greatly increase the ability of the robot to accumulate a more thorough information and understanding of the world around it. Most autonomous robotic systems will have multiple sensors (Brooks, 1986).
There are wide variety of sensors available which are capable of measuring almost anything, from environmental conditions (distance, light, sound, temperature) to angular and linear acceleration, forces and distances. The first sensor often incorporated into a mobile robot is a distance sensor, which is usually in the form of an infrared or Ultrasonic sensor. In both cases a pulse (light or sound) is sent and its reflection is timed to get a sense of distance. Usually these values are sent to the controller many times each second.
The use of ultrasonic sensors in most applications is easier, cheaper, and computationally simpler. Ultrasonic transducers are preferable to obtain three dimensional information on the environment (Borenstein and Koren, 1988).
They measure and detect distances to moving objects, are impervious to moving to target materials, surface and color, solid state units have virtually unlimited maintenance free life span. Ultrasonic sensors are not affected by dust, dirt or high-moisture environment.
The control and coordination of the various sensors and components required for the reliable performance of an obstacle detector robotic vehicle has been an essential aspect of this work down through the years. Microcontrollers are employed for this unique task. A microcontroller is a small inexpensive computer, usually used for sensing input from the real world and controlling devices based on that input. Most electronic devices used today have a microcontroller in them of some form or another. Microcontrollers are easy to use with simple sensors and output devices, and they can communicate with desktop computers fairly simply as well (Igoe, 2015). A microcontroller contains a CPU, read-only memory (ROM) in which programs are stored, random access memory (RAM) to store variables used in the execution of the program and various I/O buses to connect to the outside world. Microcontrollers over the years have evolved from a complex and complicated user interface to a friendlier and easier interface for programmers, here by increasing the chances of designing more flexible and autonomous robots.
One of the first obstacle detector robotic vehicle designed was called the Hex Avoider. The Hex avoider was a programmable mobile robot designed to move independently and avoid obstacles it was aided with infrared emitters and receivers to sense its environment but in recent years with the invent of more flexible and reliable sensors, microcontrollers and actuators, the design of Obstacle detector robotic vehicles have become more captivating and relevant as it finds application both commercially and also in the military.
1.2 STATEMENT OF PROBLEM
In recent times, there have been a tremendous rise in industrialization and technological advancement all over the world. Hence the need for accuracy and precision within an industrial environment both for the safety of the human workers and the security of the entire work environment. The obstacle detector robotic vehicle with its ability to detect obstacles within a given range and avoid collision with the obstacle brings a huge possibility for surveillance and monitoring systems of environments which are dangerous and toxic for humans to access within the work environment and beyond.
1.3 AIM AND OBJECTIVES
The aim of this work is to build an Obstacle detector robotic vehicle, which has the ability to detect obstacles on its path and avoid collision.
The objectives are:
- Review existing systems
- Design a suitable circuit to accommodate sensors and actuators required for this work.
- Construct the obstacle detector robotic vehicle using the designed circuit.
- Test for efficiency
1.4 SIGNIFICANCE OF STUDY
The design of an Obstacle detector robotic vehicle is significant as it can be used in ;
- Industries for surveillance and penetration of environments toxic and dangerous to human health.
- Indoor vacuum cleaners for use in homes and commercial buildings.
1.5 SCOPE OF STUDY
This project focuses on the design and construction of an obstacle detector robotic vehicle, the robot is developed with the collision avoidance capability in an obstructed environment. The mobile robot has been built as a fully autonomous vehicle with on-board sensors to get information about the surrounding. The mobile robot is a three wheeled robot platform which employs the differential steering mechanism for motion in given angles. Two Dc gear motors have been used for the driving wheels. The robot has an on-board Ultrasonic sensor which is mounted on the standard servo motor. The Servo Motor and the Ultrasonic sensor are controlled by a dedicated microcontroller which sends the information collected to the main controller. The differential drive method has been used as the obstacle avoidance algorithm and the Algorithm is implemented in the main microcontroller which is on the mobile robot. The Algorithm implemented is used to avoid the obstacle and to drive the robot to a locally generated goal.
1.6 APPLICATION
The obstacle detector robotic vehicle finds application in the following areas;
- Industries for surveillance and penetration of environments toxic and dangerous to human health. E,g Mining sites
- Indoor vacuum cleaners for use in homes and commercial buildings.
- Unmanned Vehicle Driving
