MicroMouse DesignThe Intellimouse ExplorerDate Submitted:May 13, 2005Sponsor: Dr. Herb [email protected]: Dr. Herb Hess & Dr. Brian [email protected] & [email protected] [email protected] [email protected] [email protected] [email protected] of ContentsAbstract iii1. Project Description 11.1 Overview 11.2 Objectives 11.3 Methods 12. Status and Preliminary Results 23. Methods 63.1 Microcontroller 63.2 Drive Components 73.3 Sensors 83.4 Chassis and Wheels 84. Validation Procedure 10Appendix 12iiiAbstractA MicroMouse is being designed to negotiate a path to the center of a maze in theoptimal amount of time. The design must integrate a microcontroller, sensors, andmotors. This paper presents the current design and interface of the different modules aswell as preliminary data related to the performance of the MicroMouse. The motors andsensors have been connected to the microcontroller and currently, the MicroMouse iscapable of moving a specified distance in a specified direction upon command, as well asto receive some sensor input and stop before hitting a wall. Future challenges lie in usingthe sensor input for maze navigation and finding the optimal algorithm for solving themaze.11. Project Description1.1 OverviewThe goal of this project is to design a self-contained, autonomous, electrically poweredvehicle called a “MicroMouse”, to negotiate a path to the center of a maze. TheMicroMouse will be built in accordance with the IEEE APEC MicroMouse ContestRules.1.2 ObjectivesFrom these rules we have generated the following objectives for our MicroMouse:• Autonomously find a way to the goal of the maze and back to the starting point.• Complete a run (from start to goal) in less than ten minutes.• Turn 360° in a single grid square of the maze.• The main body must fit inside of a single grid of the maze (16.8 cm x 16.8 cm).• The sensor wing must fit inside a 25 cm x 25 cm square.1.3 MethodsTo accomplish these objectives we have divided the project into four main components:microcontroller, drive components, sensors, and chassis. We will use a microcontroller,stepper motors and distance and proximity sensors to create our MicroMouse. TheMicroMouse will be setup using a two-wheel drive system. Stepper motors will beconnected to the drive wheels with ball casters providing balance. Distance sensors willbe used to measure the length of the path on the front, left and right sides of theMicroMouse. Knowing the distances to the walls in those directions will allow for more2intelligent maze navigation. Proximity sensors will be located on wings that extendabove the maze walls to the sides of the MicroMouse. They will detect the presence ofside walls, as well as perpendicular walls in adjacent cells. The microcontroller will keeptrack of maze information, control the navigation of the mouse, and optimize the pathback to the start.2. Status and Preliminary ResultsProject StatusUnder TestDesigned and WorkingUnder DesignBasic Movement –Motor ControlTest MazeBasic Sensor to Board CommunicationFaster Motor Control AlgorithmSensor to Board Communication AccuracyIncrease Movement AccuracyChassisComplete MazeMaze Solving AlgorithmFall Following BehaviorFigure 1: Status of Project ModulesAs illustrated by Figure 1, a majority of the modules described in the previous sectionare completed and fully operational. A more detailed list of these modules is presentedbelow: Basic assembly of all components (See Figure 2.)3Figure 2: Intellimouse Explorer Straight-line and turning movement (See Table 3 in Appendix B.) The Intellimouse is able to move in a straight-line with a deviation of 35.4 cmfrom the center path while traveling a 285 cm path. The current maximum average speed in the straight-line movement is 0.107m/s, which is a little below the desired velocity. The system is able to turn 180 degrees within a maze block in a period of 1.25seconds with an error of just over 1 degree. Current data shows that although the MicroMouse performs a 90-degree turnwith a small error, the error does not accumulate during continuous left orright turns. Test maze A 6 x 6 test maze has been built with a plywood base and foam walls. The tops of the walls are spray painted with red, while the base is black inaccordance with the specifications. The maze walls are adjustable for different configurations.4 A picture of the maze is shown in Figure 3.Figure 3: Test Maze Basic sensor to board communication Sharp GP2D12 distance sensors are interfaced to the microcontroller andsensor output is routed to the Handy Board LCD. The sensors have been tested to obtain a calibration curve of distance tonearest wall vs. voltage and microcontroller output. (See Table 4 and graphsin Appendix B.) Sensor input is used to detect the distance to the front wall and stop beforecollision. Motor control algorithm Stepper motors are driven by the microcontroller using full stepping and thebuilt in microcontroller functions. (See code in Appendix D.) Motors can be controlled to move in any specified direction for any specifieddistance.5 Full stepping results in a noticeable error when turning 90 degrees, howeverthis is corrected by alternating the number of steps between consecutive turns. Batteries The MicroMouse is powered from the on board microcontroller batteries. Thelatest data demonstrated that the batteries are capable of driving theMicroMouse for more than 1 hour and 10 minutes, which eliminates the needfor external rechargeable batteries.Under Test Redesign motor algorithm to incorporate half-stepping for increased speed. The present average top speed of the system is 0.107 m/s, and work is beingdone to increase speed to 0.5 m/s. Accurate sensor to board communication Improve data acquisition from sensors. Install Fairchild QRB 1134 sensors on wings. Use sensor data for maze navigation. Straight-line movement accuracy Decrease system deviation from center path during straight-line movement. This will be done using feedback from the proximity sensors and will alsobe improved once a final chassis has been built.Under Design Chassis Robust and compact chassis. Adequate to allow easy movement inside the maze.6 Complete Maze Create a full maze in accordance with IEEE specifications.3.