Progress Report

4-19-99

Summary

This report covers the project code named “F1: It’s how robot is DONE” being completed by Zaher Ali-Dib, James Beams, Kevin Berndsen, and Matt Caldwell from Monday, March 29 to Friday, April 16.  Despite some initial problems the project is running on schedule with the team’s personal schedule and ahead of the class’s general schedule. 

At this point, a simple chassis with two drive motors has been designed and built.  It has the ability to turn on an axis around its drive train and move at a relatively high rate of speed.  At this time it doesn’t have the ability to drive up ramps because of the wheel positions.  This will be fixed in later revisions.

Our main design flaw occurred in the drive train.  The original design for the chassis consisted of treads instead of two drive wheels and a freewheel.  Problems occurred in turning.  The rubber treads had difficulty allowing the robot to turn well on tile, and greater difficulty on the rubber competition course.  To remedy this problem the freewheel was introduced.  This greatly reduced the amount of friction caused by the large treads while still allowing the robot to turn on an axis within its chassis. 

The motors chosen for the power train are servos modified for 360-degree motion.  They were chosen due to the fact that they provide a high amount of torque needed for driving the vehicle up hills and provide a fairly fast rate of rotation.  The ability to mount wheels directly to the motors and their low cost also played in the decision to choose these motors. 

Various designs have been discussed for the pickup/sorting mechanism.  Ideas range from a simple flat scraper that marbles would randomly slide onto to a scoop with a rotating brush that brushes the marbles onto the scoop.  The current design consists of a rotating brush that is fixed to the chassis.  A scoop that can be raised and lowered by another servo either directly or by use of a string is also mounted so that the scoop is just behind the brush.  While over the marble bin, the scoop is lowered down into the bin and the brush is then rotated with a fourth servo.  The brush collects the marbles in the scoop.  The scoop is then raised enough to allow the robot to complete the course to the collection bins.  When the robot is in position over the collection bins, it will raise the scoop up to a high angle which causes the marbles to slide down a PVC pipe in back of the scoop.  In this scoop is a slit in the bottom that will allow the small marbles to escape and route the large marbles to the end of the pipe.  This movement should effectively sort and deliver the marbles in one motion.

In conclusion, this robot has a lot of potential and has had very few problems to date.  Any problems encountered have been easily solved.  The marble collection and sorting mechanism is very simple and should be very effective. 

Future Plans:

Future plans include:

-         Creating a second freewheel for the front of the chassis so that the freewheels can be mounted at the front corners of the robot to allow it to driver over the collection bin properly

-         Troubleshooting chassis so that robot can effectively maneuver around the course

-         Building and troubleshooting the marble collection/sorting device

-         Installing bump sensors

-         Installing IR sensor, CdS cell, and mercury switch if needed

-         Troubleshooting bump sensor placement

-         Writing test code to maneuver robot to marble bin with use of sensors

-         Writing test code to pick up marbles

-         Writing test code to maneuver to collection bins and deposit marbles correctly

-         Writing test code to maneuver out of course

-         Troubleshooting test code

-         Compiling test code into final code

-         Troubleshooting final code