# Pure pursuit algorithm - Transform Global to vehicle coordinates?

project: autonomous driving car

I have a small RC car, a Raspberry Pi and a camera which are fixed on the car. Now I want to let the car drive autonomous with image processing. So far I can detect the lane and get the point (x and y of the path on the image)

Now I want to implement the simple pure pursuit algorithm. While I was trying to understand the pure pursuit algorithm which is explained in this paper I read about "global and local coordinate system".

My question: Do I have to transform the (x,y) points of the path from the image to the vehicles coordinate system? If yes, how can I do this?

• My question is, just what coordinates are they in now? The camera is afixed to the car, Therefore the image moves as the car moves. Effectively, these points are already in a car coordinate system. You should know the car's heading in the image coordinates. If so, then it is just a matter of finding the angle between the car heading and the point you wish to go. – Paul Sinclair May 11 at 3:45