Building a robot is a rite of passage for any electronics hobbyist. It can be a great combination of software and hardware, with an incredible amount of customization possible it is a chance to let the imagination run wild.
Robot Kits:
Kits are a great way to get off to a running start because they come with most if not all of the parts needed. All that is required is assembly and, depending on the kit, some programming.
The jolliBot is a line following robot kit based around the Arduino Nano made by Jollifactory. It uses the TRCT5000L reflective sensor for detecting the line beneath it and following it around. The includes two DC motors and an L239D half bridge driver chip as well as a PCB and all the other small components needed to make it work. Jollifactory also provides some sample code to get your bot up and running.
Building this kit will introduce you to some of the most commonly used components in electronics as well as providing an opportunity to write some code to optimize your line follower! The Arduino nano is not included in the kit which may be a good thing if you want to use another development board or microcontroller.
This line tracking robot made by Elab Peers operates using only analog electronics, no microcontroller involved which means no code to program. It’s easy to neglect the analog side of electronics when learning but this kit provides a great introduction. This robot uses transistors, op-amps and photo-resistors to detect the line beneath it. Learning how the circuit works will benefit you down the line in other projects. Elab Peers provides a circuit diagram and build instructions in their documentation section.
The Bare Bones Approach:
Buying a kit is great in that it simplifies the process of getting your first robot up and running. One possible downside is that it also limits you to making the bot as designed by its creator. If you want more flexibility you can source the various parts for the robot separately. Broadly speaking, these parts fall into the categories of : chassis, sensors, actuators, and control electronics.
Chassis/Actuators:
This robot car chassis designed by Mmm999 is the perfect starting point for a car based robot. It has plenty of space to add a battery pack, microcontroller, and various sensors of your choosing. This chassis comes with four geared DC motors so you don’t have to go looking for them elsewhere.
Sensors:
There is a huge variety of sensors available with some being more suitable than others depending on your application. If we wanted to have this robot drive around and avoid obstacles in its path we could use an infrared obstacle avoidance sensor like the one made by Icstation. These sensors work by emitting infrared light and looking at how much gets reflected back.If there’s something in front of your robot, you’ll get some reflection, if there’s not, you won’t! This board has an effective working distance of 2-40cm and takes a supply voltage of 3.3-5V. This sensor could also be used for detecting a black line under the robot for making a line following bot.
Another way of detecting obstacles is with an ultrasonic sensor. These sensors work by recording how long it takes for an ultrasonic pulse to be emitted, bounce off an object, and return to the receiver. Ultrasonic is more suitable in environments that have either very low or very high light reflectivity, as IR sensors tend to fail in these situations. Due to the shape of the sensor they can be a little tricky to properly mount. Upgrade Industries has you covered with their ultrasonic distance sensor and mounting bracket kit. This bracket allows you to easily fix the sensor directly to your robot or to a servo so it can sense obstacles in different directions.
The Brains (Control Electronics):
The Whiteboard Nano Robot Controller board by RuilongmakerWorkshop has everything you need to get your robot moving around. It is based on the Arduino Nano and uses an ATmega328p microcontroller. What makes this board particularly useful is the motor driver chip it’s packing on the underside of its PCB. This driver chip can supply 1000mA for two channels. In the case of our robot chassis with four motors, the left and right sides could be wired in parallel, meaning it would move in a similar way to a tank. The push-to-release wire terminals make connecting and disconnecting your motor wires relatively painless.
Adding a Raspberry Pi to your robot can open up a whole new range of possible project ideas, you could easily add a WiFi dongle for Internet connectivity or a USB webcam for basic image recognition for example. The PiDroidAlpha controller for the Raspberry Pi lets your Pi control motors and read analog inputs easily. It comes with an L239D dual h-bridge motor driver chip, an MCP3008 eight channel A/D converter, and the MCP23S17 sixteen channel I/O expander. This will allow your Pi to read up to 8 analog sensors and control more than enough digital outputs for most purposes!
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The majority of hobbyist robot projects that surface on the internet use either wheels or legs as their method of propelling themselves around. It’s time to consider the under-appreciated tank chassis. Aside from looking insanely cool, it means your robot can easily handle terrain that would cause problems for a robot rolling around on wheels or using a leg based mechanism.
Programming the board is as easy as plugging in the USB cable and opening up the Arduino IDE, with serial output to the Arduino serial monitor possible thanks to the on-board FTDI chip.
