PmWiki | Student / Wall Following

Purpose

The purpose of this lab was to make the Create follow a wall using at least proportional control. Proportional control is where the robot's output values are proportional to the imput values. The "strength" of the imput determines the "strength" of the output.

Results

It took me a while to fine tune my wall following. I was able to make it follow a wall very well, but when there were objects in way my robot had more difficulty. It was able to travel around shapes like simple rectangles (ie trashcans, etc) but strange shapes like trashbags, water jugs, and picture frames gave it more trouble. Some of the difficulty that my robot was having stemmed from the fact that it sometimes got so close to the "wall" that it came inside the sensor's ranges, throwing off the program. I was able to change this by moving the sensors farther away from the edge of the robot, so that they couldn't get too close to the walls.

I also didn't add the safe mode and didn't utilize my bumpers in the program. If I had more time, I would have added these features to make the program work better.

Utilizing Proportional Control

I set up a series of equations to control the turning of my robot. When the robot was an acceptable distance away from the wall, it just went straight. However, when it got too close or too far away, it would turn based on the imput from the distance sensors.

For example, when my robot got too close to the wall (distance sensor value greater than 200)

The left wheel would turn 100-(sensor value - 200) and the right wheel would turn 100+(sensor value -200) The closer it was to the wall, the left wheel would have a smaller speed and the right wheel would have a greater speed, causing it to turn farther away from the wall.

This meant that my robot turned very smoothly on curves in the hallway!