# gps guided robot

hi everyone
i want to create gps guided car with this module:
u-blox neo 6
arduino mega
HMC5883
l293 shield
6wd Chassis kit → Wild Thumper 6WD Chassis - Black (34:1 gear ratio) - ROB-11056 - SparkFun Electronics
thanks

This appears straight forward.

Break the project down into doable chunks and then combine.
Then work on a sketch to use your motor shield to drive the motors in the chassis.

Then start combining pieces.

Add in a method to enter a destination or route with waypoints, and then logic to use all of that data to perform navigation.

If at any point, you run in to difficulties, pop back here and let us know.

my main problem is how to navigate my car to special waypoint
when to start motor and when to stop them and when to rotate the car

my main problem is how to navigate my car to special waypoint

Pretty simple, actually. The navigational formulas are presented on this site: Calculate distance and bearing between two Latitude/Longitude points using haversine formula in JavaScript. You will need the bearing and distance formulas.

One problem is that the Arduino does not support double precision floating point calculations, which is usually required for navigation using latitude and longitude coordinates. Some GPS libraries, like NeoGPS, get around this by using long integers for latitude and longitude variables.

Note: the L293 motor driver WILL NOT WORK with the motors used in the "Wild Thumper" vehicle you have selected. You need a high current motor driver.

i will try that formulas
i will use 2 of l293 shield
i try that and have no problem in short use each l293 shield can handle 4 amper am i correct?
i use this
https://goo.gl/images/rZ82UP

in short use each l293 shield can handle 4 amper am i correct?

No. It will overheat and shut down instantly.

The motors have a start/stall current of around 6 Amperes.

Do have fun trying, though!

i have problem with compass my hmc5883 show different heading angle from my phone
for example my phone shows 180 degree but my sensor shows 342 degree

Magnetometers must be calibrated in order to use as a compass. See this post and the links therein.

thanks
can you send a working sketch i try many but none of them works

The link in reply #7 contains a sketch that works for a particular magnetometer.