A CLASIC Robot

Team

Goal

Our goal is to build a mobile robot with the ability to navigate a maze, locate a token, and then exit the maze and inform other robots how to locate the token.

We hope to have something "interesting" to demonstrate at Bot-Fest, but will most likely require the entire semester to achieve this goal.

Implementation Overview

We will attempt to keep the implementation as simple as possible. The mobile base will be built of Legos, and consist of a tank tread drive system with enough room to fit a Handy Cricket, the 91.305 development board, and a bread board. The tank tread drive system will hopefully help to distribute the weight of the various logic components, while providing adequate directional control. (See Figure 1 Below)

Figure 1. Overall Design

The Handy Cricket will be the main controller for the system. It will interpret data provided by various sensors, make appropriate navigation decisions, and control the motors driving the treads. It will also have the ability to convey its navigation information to other similar robots via its IR port. (See Figure 2 Below)

Figure 2. High Level Block Diagram

For an initial implementation we would like to build a Quad-Sonar Cricket Bus Device (See Figure 3 Below). This device would control four sonar devices providing distance (in centimeters) to the Handy Cricket over the bus when requested. The four sonars will be connected to the mobile platform at 90 degree angles providing the Handy Cricket with a course 360 degree view of its surroundings. It is our intention to use four sonar inputs, and only those inputs, to navigate the maze. The heart of this device would be a LogoChip, which should have enough computational "horse power" to continually poll the four sonar sensors, and respond, upon request, to the Handy Cricket with up to date distance readings from all four sensors.

Figure 3. Quad Sonar Bus Device Design

One of the built in sensor inputs on the Handy Cricket can be used with an additional sensor for detecting our "token". For simplicity we can use some kind of a magnet reed switch to detect when our robot drives over the target area.

Implementation Road Map

1. Build a simple mobile platform that can support our three system components. (completed)
2. Build a single sonar sensor bus device with precision adequate for our navigational purposes. (completed)
3. Assemble our scaled down components and experiment. (completed)
4. Elaborate on our mobile platform and create a tank tread drive system, that is rugged enough to support the other components. (completed)
5. Enhance the single sonar sensor, converting it into a Quad-Sonar bus device. Optimize the processing algorithm to minimize the latency experienced by the Handy Cricket when requesting an update. (due 3/19/2003)
6. Prototype simple maze wandering algorithm suitible for Bot-Fest. (due 3/22/2003)
7. Design and document an API to abstract low level motor control as a higher level collection of primitives. Our maze navagation algorithm will utilize the API to control the robot. (due 3/27/2003)
8. Add Left Front and Right Front motors to increase the mobility of the robot. ( due 3/28/2003)
9. Add Magnetic Reed Switch sensor to robot. (due 3/28/2003)
10. Research and design a maze navagation algorithm incorporating the ability to save a search path, traverse the search path in reverse, and convey the search path to other robots. (due 4/3/2003)
11. Implement motor control API. (due 4/3/2003)
12. Implement and debug the search portion of the Maze Navagation Algorithm. ( due 4/10/2003)
13. Implement and debug the ability to reverse the search path, and convey that search path to other robots. (due 4/17/2003)
14. Class time intentially left at the end to compensate for missed mile stones, or professor suggestions.

Current Status

Steps 1 - 4 have been completed, although the tank tread platform has only been tested using a single Handy Cricket without sonar detectors. We think we can have a very simple robot working in time for Bot-Fest with the ability to move forwards and backwards, stopping before striking a solid object. This will also demonstrate the completed Quad-Sonar bus device, with only input from two of the sonars being used by the robot.