MINE CRAWLER PROJECT REPORT

INTRODUCTION

1.1 Brief Description

Robots are becoming more and more common in our daily lives showing up in the form of everything from children’s toys, to robotic vacuum cleaners, to home security robots; robots have been doing automated tasks in factories for decades. With the ever-increasing speed and power of digital systems coupled with the continuously expanding field of robotics, it is becoming more practical to build custom robotic systems with a degree of flexibility and freedom that was once impossible, giving robots the ability to communicate wirelessly or to act autonomously. Now, instead of robots simply performing menial tasks such as repetitive jobs at factories, robots can perform jobs once thought to be reserved for humans, without the risk a of danger to a human life. One such job that would be much safer for a robot to take on than a human is that of search and rescue. Such a robot, if it could perform its duties safely and reliably, would be of immense value to any rescue operation. The robot prototype designed and built for this major qualifying project was meant to be a starting point for such a robot; due to time and budget constraints building a fully functional search and rescue robot was not feasible.  

The robot that was designed and built for this project was intended to have some of the basic components needed to develop a fully functional environment exploring robot. While such a robot would need many complicated systems all interfaced together the design of the robot presented in this paper focused on what was thought to be one of the core functionalities needed, sensors and wireless transmission. The goal of the mapping robot was to sense the environment and transmit the data through wireless transmission.

By designing and building the autonomous mapping robot many steps were taken towards the design of a fully functional environment mapping robot. This design provides a solid base for further development of the robot by future students. The mapping robot was built around an embedded processor system. This processor was used to control the many systems incorporated into the design of the robot. The major functional blocks of this robot are its base – the platform on which all the systems were mounted, the processor, the power circuitry, the motor controller, and finally the sensors, including optical wheel encoders, ultrasonic sensors, and gas sensors. Each of these individual systems was interfaced through the processor using various drivers and programs.

LITERATURE SURVEY

Carnegie Mellon University has built several different types of mapping robots to map both indoor and outdoor terrain. On the CMU robotics website, they present information on two of their mapping robots, which are both capable of mapping in three dimensions. The first of these is designed to map a mine, while the second robot is designed to map a 3D texture map. Two robotic systems were used in their research of mapping mines. 

The first type was a cart that had to be manually walked through the mine in order to map the mine. The cart was equipped with four 2D laser range finders to provide information on the mine cross section ahead of the cart and the ceiling structure above the cart. The second type they have developed is a tele-operated device constructed from the chassis of two ATVs. This robot was equipped with two laser range finders, one directed forward and the other pointed towards the ceiling. 

In order to map out an accurate 3D map, the researchers developed a complicated algorithm which was explained in their report. The Groundhog, as the robot is known, was not equipped with an odometer or an inertial sensor to obtain the robot’s global coordinates, however their algorithm allows them to calculate an estimate of the robot’s location by taking two consecutive scans and calculating the relative displacement. Though the robot used to do their mapping does not exhibit autonomy like the one presented in this paper, their mapping algorithm and strategies are great resource to us.

The 3D texture mapping robot designed by students at CMU was equipped with a home-made panoramic camera and two laser range finders. The panoramic camera was constructed by simply combining a camera with a convex mirror. This allowed the camera to record its surroundings without having to move it. They achieve their goal by taking data points using laser range finders and combining that data with the images taken with the camera. Both of these robots were successful in constructing 3D maps and were great examples to examine. The only concern is the cost of these robots. 

One of the constant themes seen in these robots was the use of laser rangefinders to gather the data needed in order to make the actual map. While multiple lasers were needed in order to build 3D maps this would not be the case for this robot. Another valuable resource gained from these projects was the algorithms which were developed for use with each of these sophisticated robots.