Making One Cubic Inch Micro Robot
Here are some details on building small robots and circuits. This Microbot will also cover some basic tips and techniques that are useful for building robots of any size.
For me, one of the big challenges in electronics is seeing how small a robot can be. The great thing about electronics is that components get smaller, cheaper, and more efficient at an incredibly fast rate.
Imagine if car technology were like this. Unfortunately, mechanical systems right now don’t advance nearly as fast as electronics.
One Cubic Inch Micro Robot
This leads to one of the main difficulties in building one cubic inch micro robot. We trying to fit into a small space, the mechanical system that moves the robot. The mechanical system and batteries tend to take up most of the volume of a really small robot.
Image 1 shows Mr. Cube R-16, a one cubic inch micro robot that is capable of reacting to its environment with music wire whiskers (bumper switch). You can move and explore the perimeter of a small box. It can be controlled remotely using a universal infrared TV remote that is configured for a Sony television.
You can also have your Picaxe microcontroller pre-programmed with reaction patterns. Details start at step 1.
It is one cubic inch micro robot that measures 1″ X 1″ X 1″. It is capable of autonomous programmable behavior or can be remotely controlled. It is not intended to be something that is very practical or particularly useful.
It is simply a prototype and proof of concept. However, it is useful in the sense that building a small robot allows you to hone your miniaturization skills for robots and other small circuits.
Building a Small Robots and Circuits
Note that building as small as possible means that it can take twice as long as it would normally take to build the same circuit in a larger space.
All kinds of clamps are needed to hold small components and wires in place while soldering or gluing. A bright work light and good headphones with a magnifying glass or a fixed magnifying glass are a must.
Small Micro Motors
It turns out that one of the biggest obstacles to making really small robots is the required gear motor. The brain control electronics (microcontroller) continues to decline. However, finding low rpm gear motors that are small enough is not that easy.
1 inch cube uses small pager gear motors that have a 30: 1 ratio. In that gear, the robot is faster than I would like and a little nervous. To adapt to the space, the engines had to be offset with one wheel further forward than the other. Even with that, it moves forward, backward, and spins well.
The motors were wired to the profiling panel with 24 gauge wire which was soldered and then bonded with contact cement. At the rear of the robot, a size 4-40 nylon bolt was screwed into a threaded hole underneath the bottom circuit board.
This smooth plastic bolt head acts as a wheel to balance the robot. You can see it in the lower right corner of image 4. This gives you about 1/32 “clearance at the bottom of the robot.
To mount the wheels, the motor mounted 3/16 “plastic pulleys were turned on and then, while turning, sanded to the correct diameter.
They were then inserted into a hole in a metal washer that fits inside a washer. Nylon and all epoxy together The wheel is coated with two layers of Liquid Tape rubber for traction.
Small Lithium Batteries
Another problem with smaller robots or one cubic inch micro robot is finding small batteries that will last. The gear motors used require fairly high currents (90-115ma) to operate. This results in a small robot that eats batteries for breakfast.
The best I could find at the time were 3-LM44 lithium button batteries. The battery life in very small robots of this type is so short (a few minutes) that they generally cannot do anything close to practicality.
There was only room for three 1.5v batteries, so they ended up powering both the motors and the Picaxe controller. Due to the electrical noise that small DC motors can create, a power supply for everything is usually not a good idea. But so far it’s working fine.
The gap in this one inch robot was so tight that the thickness of the 28-gauge wire (flat ribbon) insulation turned out to be a problem. He could barely bring the two halves of the robot together. I estimate that about 85% of the robot’s volume is full of components.
The robot was so small that even an on / off switch was problematic. Eventually, he could replace the raw whiskers with infrared sensors. I’ve literally run out of user-friendly space, so adapting anything else without resorting to surface mount technology would be an interesting challenge.
I like to use one cubic inch micro robot construction for really small robots. See Picture
1. Consists of two halves that snap together with .2 “band headers and plugs. This provides easy access to all components, making it easy to debug circuits or changes.
Image 2 shows the location of some of the main components.
How to Making One Cubic Inch Micro Robot. Find out and learn more at my website www.MircolabProjects.com.