thommynator / slamrobot Goto Github PK

Description:
If the robot drives forward and backward multiple times, it won't drive on the same line/path.
It shifts to the side during this process.
This problem only appears, if the robot is not driving in multiples of 90°, e.g. 45°.

Hint:
After computing the new pixel position (moveForward(), moveBackward) of the robot, the position is rounded. This rounding error leads to wrong positions.

General

RANSAC is used to find landmarks (i.e. walls) in the environment of the robot.
This works fine for horizontal (parallel to x-axis) walls.
The walls are represented as linear functions, that are estimated by a least squares estimation.
This estimation doesn't work for perfectly vertical aligned points, i.e. for each wall parallel to the y-axis.

Details

Each measurement consists of a x-coordinate and y-coordinate.
If all measurements are vertical aligned, all their x-coordinates are equal.
The least squares estimation tries to find both parameters (a & b) of a linear function: f(x) = a * x + b
Problem: There is no solution for this equation, if all points have the same x-coordinate but different y-coordinates.

I need a more robust way to estimate vertical lines.

Example

Horizontal RANSAC Line:

Vertical RANSAC Line:

As you can see in the images, the vertical walls are not detected.