08-16-2017, 09:08 PM
This is my maze solving robot project which worked out pretty well. I have put up my whole project report that i submitted to my college but i have chucked out the exact code. if i get a good response and demans then i will surely give you all the exact working code of my project.If you are interested only to learn about the algorithm and not worried about the design pl skip to the section 5 of this text.
1 INTRODUCTION
Atonomous robots have wide reaching applications.From Bomb sniffing to finding humans in wreckage to home automation.Major problems facing designers are power and reliable sensing mechanism and unfamiliar terrain obotic competitions have inspired engineers for many years.Competitions are held all around the world based on autonomous robots. One of the competions with the richest history is micro mouse . The micro mouse competitions have existed for almost 30 years in the United States and it has changed little since its inception. The goal of the contest is simple. The robot must navigate from a corner to the center as quickly as possible.The actual final score of the robot is primarily a function of the total time in the maze and the time of the fastest run.The specificatons for the micro mouse event is specified in appendix A. The Design incorporates various techniques to simplify the approach and make an effecient automated robot.
2 MICROMOUSE DESIGN AND HARDWARE
The Major criteria of micromouse design remained the size of the robot which will allow smooth 90-degree turns and U-turns possible. After detailed analysis regarding the maximum dimensions of the robot the initial dimensions to start with were
finalised as 10cm x 10cm.
The Micromouse hardware required two stages.
1. Choosing the type of motor
2. Building the chasis
The micromouse was made initially with a DC motor,since the strategy revolved around using very accurate sensors which can be easily used to regulate the non-linearity of the DC motor.DC motor has its own advantages of higher torque even at low cost motors.The initial design planned incorporated four 6F22 9v general batteries,which posed considerable weight considerations. This was tackled successfully by the use of a good gear system. The weight of the robot was planned to be lesser than 500gm
which would facilitate free motion of the robot even on rough surfaces.The number of wheels was a major factor of thought,A four wheeled robot would find it difficult to negotiate turns while giving a steady straight motion. the three wheeled robot was on cards that can negotiate turns with ease, Major disadvantage being ,it capable of maintaing steady straight motion on straight runs. Sensing devices have been traditionally classified as Over-thewall or Under-the-wall . The original micromice used the red paintted wall top to determine the orientation,like a long wing like sensor arrays extending over the walls.Recent designs avoid the large moment of inertia due to huge wing arrays of the sensors and have opted for low riding mice that measure the distance from inside the wall.The latter design was markedly superior, and permitted extremely compact designs.Sensor design will be discussed in section 3. In hardware consideration of the design it was decided to use optical sensors rather than the ground-contact(rolling) sensors. The mechanical design ot the micromouse was completed on paper, drawn with relative scale.
3 SENSOR
In order to execute the algoritm accurately and and prevent the robot from crashing into obstacles the robot has to see the environment it is moving in.There are major considerations on the design of the robot since varied approaches can be introduced in the way the robot sees its environment. One elaborate but accurate technique is to measure the intensity of the optical wave and finding the distances of the robot from the obstacles at short distances. A very simple rather not so accurate technique is the move at accurate distances per move and keep counting the cells and keep the robot aware of its current location in the maze.Major problem posing this approach was the fact that when a motion is set up after a halt the wheels would slip before they actually start covering their ground,what automotive engineers call grip-slip for a typical rubber tyre.The wheels selected for the design were plastic hard wheels for easier design approach that offrerd more slip over smooth surfaces. It is obvious that we need some amount of wheel slip is necessary to exert the acceleration force.Worse,the actual grip slip is dependent on the surface type and all that is known is that the ground is black in color and it absorbs light.Thus to capitalise all the drawbacks on the accurate movement of the robot, repeated testing was required to find average yet accurate motion. primarily it was decided to design short range sensors that can just detect the presence of obstacles and not calculating the distance of the robot from the obstacle.A simple hardware approach essentially required more tedious programming technique. it was a trade off between hardware or software approach. It was decided to tackle problems on software grounds than hardware.