Let's Make Robots!

RC Car managed by Java leJOS NXJ

Drive with an autonomous systems using ultrasonic sensors and GPS
CIMG0045.JPG30.44 KB

This project tries to manage any RC Car which you can purchase in your city using a NXT brick and a Lattebox NXTe.

I am finishing a preliminar GPS navigation solution for leJOS project, but I have a problem to understand some value, azimuth.
In my tests I had some problems to understand the azimuth value which is returned by the method AzimuthTo in a Coordinates Object. AzimuthTo return an angle which is referenced with North pole.

In my tests I use a GPS point as goal:

Goal: 40.445049309324573,-3.4673066139221191

I give you a GPS point which is located on the street where I did my tests:

Current: 40.445049309324573,-3.4673066139221191

If you make a line bettween the both points, the line is on the street but azimuth give a value 144º so if the robot change the course to angle 144, so the robot would leave the street. I don't understand how to use the value 144. Is it neccessary to make any trigonomical calculation to find the solution?

I have made a doc about the problem and some questions:

I made some videos about the system:

Do you have an alternative calculus to make the azimuth calculus?
Do you undertand my problem?

Today I begun to test my first GPS Navigator. Besides I have to improve the system which manage the steering maybe using PID or another technique...


If you take a look the prototype, I have uploaded some pics in my Flirck account:


This year I will use a new RC Car chassis, Maverick Strada model which I replaced some pieces, for example the speed controller. With this model, the place where is located NXT brick is more stable.

I have released a new gallery about this model:

NXTe allows me to control RC Servos and DC Motors easily. Currently I can go forward and backward. leJOS project has worked so hard to improve garbaje collector, to manage with NXT's CPU complex Java Programs.

I have released a new RC Controller. I am working on this tasks:

  1. Integrate GPS Subsystem
  2. Integrate Google Earth Support
  3. Improve autonomous subsystem
  4. Develop GPS Navigation
  5. Research Kalman Filter to make sensor fusion

I have published a map where you can see the place where I am doing the tests. I need a large area to test algorithms.


Further information here: http://www.juanantonio.info/jab_cms.php?id=228

Note: In my website, in the previous URL, it is possible to download a paper about the project.


Juan Antonio Breña Moral

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

Yes My robot has a GPS incluided inside, I tried to say that the robot communicated with a remote control with this range, but the robot could use GPS data without any remote control.



Juan Antonio Breña Moral

aah nice, so the robot could find its own way from point A to poin B simply by navigating its way using the onboard GPS?

 Of course friend!

Continue with your project, but with less than 200$ you can test NXT with Java leJOS a JVM

Good night from spain

Juan Antonio Breña Moral

hey m8, do connect the GPS to the NXT brick or do you connect it to another chip/controller?

it looks like the NXT is just to control the servo's


NXT Brick make a BT connection with the GPS. I have to make another video with GPS Features. but now in spain the weather is bad, but no problem. Besides I have to write a paper about GPS with leJOS.

I have posted some papers about leJOS here:




Juan Antonio Breña Moral

cool i cant wait for the video :D

Are you studying robotics or is this just a hobby? I am studying software engineering and would like to start a degree in robotics when i have finished my current degree. As soon as my student loan comes though i will put some money aside to start building 1 of these! :P

Is this right?

You enter GPS co-ordinates into the GPS, then the GPS sends the DATA via bluetooth to the NXT brick and then the NXT brick controls the servos to make the robot move to the GPS co-ordinates that you entered?

I'm hoping its something like that :P I don't want to have any link to the robot once it has been given the co-ordinates :D

By the way, its SUPER CRAP weather in london :P

I dont get why people skewer the perfectally fine (not to mention understandable) NXT program.....


 It looks like you have a very interesting project.  I am wondering about the accuracy of GPS.  It is my rough understanding that you can only expect 3-5 meter accuracy for GPS.   If you are trying to follow a path, it could easily be 5 meters to one side or the other.  Am I incorrect in understanding today's GPS accuracy, or is that good enough for your project? 


Yes, you have reason, but i will incorporate a functions to improve the accuracy.