Help Maze solving

[charlie1218]

Hi,
For my engineering class we need to configure a vex platform to solve a maze made of 2inx3in wood blocks. The sensors we are given are 2 limit switches 4 bumpers 1 ultrasonic. There will be "rooms" and we will essentially need to travel no greater than 6 inches away from the wall. any ideas?

[Boydean]

A kid on our programming team did it once with Lego NXT kit, and it used three ultrasonic. I can't image it being that harder with Vex taking accepting the fact that its easer to use variables in the Vex programming system....allot easer.

[Billfred]

Just to clarify the task, is your main issue navigating the maze or staying within the reach of the wall? Maze navigation is particularly simple, particularly if the entry and exit are on the outer perimeter of the maze, though the software issue of wall-handling may be trickier.

[charlie1218]

Here is the problem: A maze with a set entrance, no exit. A candle will be placed within 6 inches of the wall, we must follow the maze so we can find the candle with the light sensors.

[rhoads2234]

you can do a simple wall following routine to start - This approach would use maybe 2 touch switches

have one touch (limit is better but bump would work) on the side of your robot and another facing the front
the code would basically say
while not front sensor not pressed
{ if side sensor is pressed turn away from wall
if side sensor is not pressed then turn into wall}
GetOutOfCorner();
With this you could follow one side or the other around..

[charlie1218]

Let me clarify. at this time we are running this a project where we need only to continuosly follow the walls, as if the flame were not there. only 1 ultrasonic, standard kit of metal and other parts/gears/motors.

[rhoads2234]

Originally Posted by charlie1218

Here is the problem: A maze with a set entrance, no exit. A candle will be placed within 6 inches of the wall, we must follow the maze so we can find the candle with the light sensors.

This sounds alot like the PennState Abbington Fire Fighting competitions..
if it is then one way to solve the problem is to look for the white mat the candle is placed on(by testing the amount of time on the white) and then scan for the candle you would be much more accurate

[EricH]

One ultrasonic, one touch. Ultrasonic aims to the side, bump to the front. Use the ultrasonic to stay within 6" of the wall. If you hit something, have the robot back up slightly, turn away from the ultrasonic sensor, and find the new wall. If the ultrasonic reads more than 6", turn into that side and move forward. Repeat as necessary to find a hole.

[charlie1218]

Originally Posted by rhoads2234

you can do a simple wall following routine to start - This approach would use maybe 2 touch switches

have one touch (limit is better but bump would work) on the side of your robot and another facing the front
the code would basically say
while not front sensor not pressed
{ if side sensor is pressed turn away from wall
if side sensor is not pressed then turn into wall}
GetOutOfCorner();
With this you could follow one side or the other around..

I like this. I like it alot, one question though, how would we do the turn into wall if there is a hole in the wall (an "entrance" into a room), keep truning until side is pressed? and we would want to keep the robot with the same side on the wall at all times.

[charlie1218]

Originally Posted by rhoads2234

This sounds alot like the PennState Abbington Fire Fighting competitions..
if it is then one way to solve the problem is to look for the white mat the candle is placed on(by testing the amount of time on the white) and then scan for the candle you would be much more accurate

Exactly. I will be entering in that later... as well as their mini darpa challenge, which i am working on now (search under "trig")

[charlie1218]

Originally Posted by rhoads2234

This sounds alot like the PennState Abbington Fire Fighting competitions..
if it is then one way to solve the problem is to look for the white mat the candle is placed on(by testing the amount of time on the white) and then scan for the candle you would be much more accurate

You cannot see over the walls, part of the rules for our competition, so you will need to be in the same space as the candle

[rhoads2234]

Originally Posted by charlie1218

I like this. I like it alot, one question though, how would we do the turn into wall if there is a hole in the wall (an "entrance" into a room), keep truning until side is pressed? and we would want to keep the robot with the same side on the wall at all times.

that is excatly what the code tells it to do it would follow the wall around teh egde and into the room - I have used similar code for line following with a single sensor

If you don't want to keep the robot on the same side the entire way around I don't recommend using this approach. If all the walls touch the outside this will get your robot all the way around the maze

[rhoads2234]

Originally Posted by charlie1218

You cannot see over the walls, part of the rules for our competition, so you will need to be in the same space as the candle

you can't in PennState's comp either - in their comp the candle has a white mat around it and you must be on the mat when you extinguish the candle