The micromouse competition has been running since the late 1970s around the world. We have a page about the early history of micromouse.
Essentially, you have a wooden maze made up of a 16 by 16 grid of cells. Mice must find their way from a predetermined starting position to the central area of the maze unaided. The mouse will need to keep track of where it is, discover walls as it explores, map out the maze and detect when it has reached the goal. As if that was not enough, the winner is the mouse that manages this the fastest.
The maze is about 3m square and has 256 cells. The goal is in the centre. Each mouse gets a limited time to make up to five runs (typically). On the first run, the mouse will usually just search for the goal of the maze, mapping all the walls it sees on the way there. After that, a mouse may opt to do further searching so that it can find the best possible route. That may not be the least number of cells – a smarter mouse will try to find a route hat it can run fastest. Once the best route is found, the robot will return to the start and make a series of runs, each faster than the last. The winner is the robot that can navigate from start to goal in the least possible time. Note that all this is fully autonomous. The on-board computer works out everything. All the mouse handler can do is clean the tyres and, often, set the current run speed.
This video shows a complete session for the winning classic micromouse in Japan 2017
Half Size Micromouse
Around 2009, contest organisers in Japan decided a greater challenge was needed and they began half-size micromouse. The aim is the same, the rules are almost the same but everything is half as big.
Building a half-size micromouse may seem pretty hard but there have been a lot of helpful developments in small components lately that have arisen from smartphones and tiny drones. With care, it is possible to assemble remarkably compact and complex robots. This example has six motors and six wheels. The four corner wheels are for steering and the centre wheels are drivers.
You don’t have to go to that much trouble. Much simpler designs are possible.
The half size contest has very similar rules to the classic contest except that the goal can be any pre-defined block of cells in the maze. Searching can take a lot longer so the time limit is increased from 5 minutes for the classic contest to 10 minutes in the half-size contest. Here is the 2019 All Japan champion performing just the search.
but the speed runs are still impressive.