Projects / Lego Rover

Lego Rover

This rover vehicle is built from Lego Technic parts and is driven by two Lego motors, which are controlled by a Raspberry Pi Zero on the rover. The caterpillar tracks allow it to drive over obstacles and turn on the spot. It can be controlled remotely from a web browser with a live camera feed from the onboard camera.

Here are some videos of the rover being driven around. I'm controlling it remotely from an iPad. The last video shows it being controlled from a web browser, with the live camera feed from the rover displayed in the browser. (No cats were harmed in the making of this video). See the Remote Control page for more details. Have a look at my YouTube channel for all my project videos.

Parts

Below is a list of the main parts you'll need to build a similar rover. You don't need these exact parts and many could be substituted for whatever you have or can get hold of. I will explain more about how they are used in the construction and electronics sections.

• Lego Technic parts - We used parts we already had. Many of them, including the yellow and black pieces on the outside are from the Technic Mine Loader set (42049) that my son got for Christmas a few years ago. Most of the construction could easily be changed to use what you have.
• Wheels and caterpillar tracks - These came from a non-technic vehicle set we had, possibly a Ninjago vehicle. They are quite important for the steering of the rover, so it would be best to get some if you don't have them. You can often get parts like this separately on ebay. You can of course build a robot with wheels instead, but there are more issues with steering to deal with.
• Lego motors, lights and wires - The 2 motors and lights in this build came from the Lego Power Functions set (8293), which looks like it has been retired now, but the motors and lights are still available on the lego website. The motors are the medium size and designed to run off 9V (the set came with a 6 AA battery case). I also used some extra power functions extension wires to cut and connect the motors to the terminal blocks on the breadboard.
• Batteries - I used an 8 AA battery box, so that I could use 8 rechargable 1.2V batteries (8 x 1.2V = 9.6V). This works well as the voltage drops a bit through the motor control chip. You could alternatively use 6 non-rechargable 1.5V batteries (6 x 1.5V = 9V) or the original power functions battery box if you have that set.
• Raspberry Pi Zero WH - The W version has the built in WiFi, which is needed here for remote control. The H version has ready soldered on GPIO headers, so you don't need to do any soldering. You could use one of the other Raspberry Pi models instead, but you would need to modify the build a bit to fit it in and maybe use different GPIO pins. I have a case on my Pi Zero to protect it and it makes it easier to hold with lego. I also have a ZeroCam camera attached that I will be using to get some pictures and video from the rover later.
• Breadboard and jumper wires - I used a small (approx. 5 by 8cm) breadboard to put all the electronics on. I've connected everything up with several colours of solid core wire and breadboard jumper wires to connect to the Raspberry Pi. It's good to have a variety of colours. I've used red for power connections, black for ground and other colours (yellow, green, etc) for control signals. You can buy all theses parts cheaply from electronics shops or on Amazon.
• L293D motor driver - This is black chip you can see in the middle of the breadboard. It allows two high voltage (9V in this case) motors to be driven forwards and backwards by 4 x 5V control signals from the Raspberry Pi.
• L7805CV 5V power regulator - This is the little 3 legged chip you can see standing upright. This regulates the 9V power supply down to 5V for the Raspberry Pi and control logic connections.
• Micro USB cable - I have chopped the end off a spare micro USB cable and used this for the 5V power supply to the Raspberry Pi.
• Other electronics parts - Four 2 pin terminal blocks are used to connect the power and motors to the breadboard. I have also used a small green LED as a power indicator, connected with a 330 ohm resistor and used 2 10nF (103) capacitors across the motor outputs. You will also need basic tools for cutting and stripping wires, small screwdrivers, etc. But there is no soldering involved in this build. All of these parts are cheaply available and you will need them for many electronics projects.
• Laptop/tablet/phone - To connect via an SSH terminal on the Raspberry Pi over WiFi and run the program to control the rover. And also to program it unless you connect a keyboard and monitor directly to your Raspberry Pi for this. I am using an iPad with the excellent Textastic app for editing code and SSH connection.

I'll explain the construction, electronics and programming for the rover in detail in the following sections.