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

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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

 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

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?

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

Hi mate, 

with a normal bluetooth connection a remote control has a 10-20m. of range but it is possible to send commands and the robot can go and come back to a distance to make a reconnection.

with arduino I know that exist a version with a bluetooth connection, then it is easy to connect with a GPS receiver with a SPP connection

I don't use this kind of chip. I like to use Java.



Juan Antonio Breña Moral

damn, although it is impressive, 10-20m range is rather short :(

I would like to have a robot that constantly checks it position with GPS and then keeps moving to the programmed position :P

There must be a way! :D


Currently with the low temperature in spain, this project is stopped for the moment, but I am doing many changes on it.

Currently leJOS project supports Mobile Phones to exchange data  with Java Streams between a Mobile and a NXT brick (I have an example in leJOS SVN), then I will replace RC Controller 2 by a Mobile phone which. Integrated a GPS on the RC Car, but now I am going to integrate a S60 Mobile phone with a GPS Inside to balance the process between 2 CPUs.

 On Facebook exist a group about leJOS project, if you are interesting about leJOS, join!

Do you have a NXT brick?

Juan Antonio Breña Moral

no i dont have a NXT brick.i would love to build 1 though. I want to interface it with a GPS device and program my robot to go to a location using the GPS to navigate. do you have a schematic for the basic layout of the system?

what is the range of the RC using the GPS?

 By the way, have you ever thought of using a basic stamp 2 chip?

Hey mate, this is really nice and I have been looking how to do this for a while now. How far can this thing go? Does the RC car receive GPS co-ordinates and then just move towards the programmed target co-ordinates? Do you have a guide on how to do this? I would really like to make one!

 Keep up the good wotk, take care