Autonomous GPS Car

I have started a project where i used a 4 wheel car with DC motors, i am controlling them through 2 dual H=bridges with arduino . I am using gps data to go from one point to target specified by the user. The problem is the robot is not succeeding reaching the point. i also used magnetometer data to calculate the degree of rotation and the error heading. I m thinking maybe the problem is the gps data , or maybe in the movement of dc motors, help plz.
PS : i am using sensoduino too instead of shields

Are you using a commercial robot product or doing everything from the ground-up ?
There are many different issues that can cause this in the code, what exactly happens? Will it go close to the point or not even related to it ?

This project we found online might help:
GPS Guided Autonomous Rover

thank you,
It’s not even related the robot keep going in circles without changing its motion that depends on error calculations

There might be something wrong in the code handling the GPS information and/or the Magnetometer.

Do you have any experience with GPS ? can we talk on private ?

Abir, you wrote indicating that something is not working correctly, but have not provided any details at all about your setup, the products you have, if it’s a commercial robot or if you put together parts to create a custom robot. In order to be able to provide even some guidance, you need to provide significantly more information about your setup, the symptoms etc. Unfortunately at this time RobotShop does not provide free consultation services. If it’s a commercial robot which you purchased via RobotShop which is not working correctly, we will do our bes tot troubleshoot, but if it’s a custom project, you will need to provide significantly more details. The community is open and although RobotShop staff / moderators / forum members will likely only be able to provide some helpful hints to help you diagnose the issue.