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Date:      March 19, 2002
To:         Executive Design Team
From:     Sub-Design Team
Subject: LEGO Robotics

1. Introduction

The problem presented to us was to create a LEGO Mindstorm wheelchair, car and defender to participate in the obstacle course and report the results to the Executive Design Team.  We had only three weeks to complete this task.  Given to us was a cubic foot and half worth of LEGO Misdstorm products to build with, yet we were allowed to use any materials we could find as long as they did not damage the LEGOs.

The robot could not be any larger than a cubic foot, but could be any weight.  It must also be able to carry monchichi through the entire obstacle course safe and sound.  Lastly, the RCX computer that runs the robots must contain a separate program for each the robotic wheelchair, car and defender robot.

Further Constraints:
1.   The robots must begin not in motion on the course and cannot be touched during the  duration of each round.
2.   No human intervention is allowed anywhere on the course after a round has begun.
3.   All energy sources must be contained within the robot.
4.   Electric motors are the only allowable propulsion systems.
5.   All alterations must be approved by instructor.
6.   Homemade sensors or gadgets are encouraged.
7.   The obstacle course will be lit by florescent lamps.  Teams will be given time to test ambient light levels on the day of the contest.
8.   All parts used that were not provided at the beginning must be approved and priced.
9.   All parts used must be itemized.
10. Devices that compromise the safety other people or other machines are prohibited.  Unsafe machines will be banned, but will be allowed to re-enter competition after the safety concerns have been corrected.
11. Weapons are allowed, but must be operated under the safety code of rule #8.  Devices using projectiles (tethered or otherwise), rockets, explosives, open flame, caustic chemicals, fluid or cut-off discs are strictly forbidden.  BTW, Flying Robots are not permitted.  The costs of such devices must also be included in the price calculation for the robot.

Our primary goal was to conduct performance and prototype testing in order to provide the Executive Design Team with invaluable recommendations for the design of the robot machine.  Secondarily, we would have liked to win the competition by finishing the obstacle course with our wheelchair, having a car program that worked perfectly and halting any competing robots with our defender program.

 

1. Performance Results and Discussion

The performance test the day before the competition gave us a good chance to test out our physical engineering and our programming.  The wheelchair program failed at a few points.  First of all, the wheelchair did not stop at the crosswalk, but continued on and collided with the car robots.  Also, when the wheelchair hit the first wall, it did not turn to the left towards the defender free zone.  Climbing the ramp, stairs and working its way through the sand pit were all successful endeavors for the wheelchair.
The car did cross back and forth over the crosswalk like it was supposed to, yet when message #1 was received it did not stop moving.  Instead it continued forward into the wall and just kept pushing.  This meant the robot did not run into any wheelchairs because it was out of the way, but it still was not functioning correctly and we would have points taken away in the competition for this.
Lastly, the defender seemed to work pretty well.  The trap door did open in order to dump the black paper, tin foil and marbles, yet not all of the materials came out.  We decided, in the future, we would put the heavy marbles on top in order to flush out the lighter materials.  We did install the clothesline at this time because we wanted it to be a surprise for the competition, but it seemed like the programming was perfect for when we would add it.

The results of the competition itself were not very much of a surprise for our group.  Our wheelchair succeeded at the crosswalk, but failed miserably when maneuvering after the defender free zone.  The walls caused us problems as we easily became stuck in the corners and were easily turned around headed back towards the entrance.  The other defender bots easily halted us since every time our bumper touched anything our robot made a large turn which usually sent us in the wrong direction.  If we were to do our wheelchair again we would remove the bumpers and just program the movement of our wheelchair according to timing.
The car was a success.  Due to reprogramming after the performance test, our car performed perfectly.  It did not collide with any other cars or wheelchairs.  Furthermore, after it received message #1, it would go forward until it the wall and then stop.  There is no way we could see to improve our car.
The defender robot was awesome.  No wheelchairs made it past our defender.  Our programming was perfect; the defender backed up for a few seconds applying the mousetrap glue to the wall and then went forward extending the clothesline that was attached to the glue and the back of our robot.  After a couple seconds of going forward, the trap door opened which released all the black paper, tin foil and marbles.  The robot continued forward until one of the bumpers hit the wall causing the robot to stop.  The dropped debris did not have a chance to stop anyone since it dropped in large piles that were easy to miss.  The clothesline, on the other hand, stopped any wheelchair that tried to drive up the stairs.  One group hit the clothesline straight on at full power and was stopped in their tracks.
In conclusion, we feel we made some improvements after the performance test that helped our score out on competition day.  The Executive Design Team should definitely consider using our car program and the clothesline we used for the defender, but the wheelchair programming is something that should not be emulated.