leJOS Features

This category contains 28 posts

Improving position tracking of a mobile robot

In a number of previous articles I’ve discussed a line following robot and the monitor program that runs on a PC to show the robot in action. This monitor program displays the position of the robot as it moves around the track. This position or Pose data is transmitted from the robot to the PC on a … Continue reading


The BNO055 IMU or Intelligent 9-axis absolute orientation sensor as Bosch like to call it is a sensor that combines a 3 axis gyro, accelerometer and magnetometer in a single small package. In many respects this makes it similar to products like the Mindsensors AbsoluteIMU and the Dexter Industries dIMU, however the BNO055 has two features which … Continue reading

I2C on the EV3

For some time now I’ve been working to improve the i2c capability of leJOS on the EV3. In particular to enable operation at a higher speed than the standard LEGO devices and to improve compatibility with devices using standard pull up resistors. Devices designed to work with the NXT/EV3 must operate at 9.6Kbps and have pull … Continue reading

Line following with openCV

In a previous article I built a simple line following robot. I had intended to follow this article up with more about building cooperating systems, but I’m afraid I got distracted! In particular I spent some time adding openCV (the open source image processing project) to leJOS. As a result I wanted a project to explore what … Continue reading

EV3 LIDAR Sensor

I had planned that my next article would be part two of the series on line following (part one is here), however a new sensor from a company call PULSEDLIGHT (http://pulsedlight3d.com/) caught my attention. Basically this sensor (the LIDAR-Lite) provides a relatively low cost laser based range finder that provides centimetre resolution with a maximum distance … Continue reading

LeJOS navigation: The Chassis

The next version of leJOS EV3 (the one after 0.9.0-beta) will bring a new addition the the navigation classes, the Chassis. It serves as an abstraction of the drivetrain of a mobile robot and translates movements of the robot into instructions to the motors. The Chassis encapsulates the the math involved in this process and makes … Continue reading

EV3 to EV3: Running text. Take two!

In the previous article we saw how things don’t always go to plan when trying to put together demos. In this post I want to describe an alternative approach to the same problem (creating a running text display over linked EV3s) that works. The standard leJOS remote API basically provides a way to access the … Continue reading

EV3 to EV3: Running text. Sometimes things don’t work!

  When I first started planning this series I wanted some easy to describe simple examples of using multiple EV3s together to demonstrate the various leJOS APIs. One of the first examples I came up with was that of a running text display. I wanted to place the EV3s next to each other and have … Continue reading

EV3 to EV3: Motor control

In the previous article we saw how leJOS can be used to control the LEDs on remote EV3s, but what about motors? Can the same technique be used for those? Let’s take a look. Like before we are using 4 EV3s all connected together in a PAN using Bluetooth, this time each EV3 has two … Continue reading

EV3 to EV3: Using remote methods

In previous posts we have looked at how we can connect multiple EV3s together into a PAN (Personal Area Network), in this article we will see how we can use the PAN to allow us to write a simple program to control the resources of one EV3 from another. There are several ways to create this … Continue reading

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