Micro Mouse--A Brief Description Jeff Weisberg (portions
by: Peter Newcomb, Joe Rosato, Otten, Kassakian, Bodmer, etal...)
Micro Mouse is a clever little gadget with a silicon brain that finds its way through an arbitrary
maze. It competes against other members of its species, racing as fast as it can.
In a Micro
Mouse contest the contestants design and build a small, self-contained, autonomous robot to
negotiate and solve an unknown maze in the shortest time.
A Micro Mouse is an electro-mechanical device, typically consisting of three
main subsystems. The drive system, an array of sensors, and the control system.
system consists of a mechanical chassis, a set of motors, gears and wheels. The chassis is usually
designed to operate like a wheel-chair, with two large drive wheels on either side of a lightweight
aluminum frame. The chassis is built to house the motors, gear system, batteries, and circuitry, and
must also be small enough to manuever within the constraints of the maze.
The control system is
series of circuit boards functioning as the brain of the critter. The control system runs a maze
solving algorithm based on the information recived by the CPU from the sensors. Typically the first
several runs through the maze will be a search sequence, in which the mouse learns the maze and
stores it in memory. It must then calculate the fastest possible path, which it will repeatedly run
trying to achieve successively faster times.
The final sub-system is the sensors. They report
to the CPU the current state of the suroundings--where the walls and paths are. These are usually
either infrared sensors which pick up light reflected off of the tops of the walls, or a sonar
system which recieve reflected sound waves off of the walls.
Each mouse must be fully
autonomous, they may not have any form of control link to an external source.
In an official
Micro Mouse contest, the main objective is to achieve the fastest maze running time. However,
another important objective may be the use of a Micro Mouse as a student project at engineering
colleges. Because it integrates several different disciplines of engineering, ranging from
electrical to mechanical to computer science, it can offer a valuble learning experience.
In the spring of 1991, a student from the Rochester
Institute of Technology came to the University of Rochester to round up support for their Micro
Their motive was simple. With only two people in their group, they needed more man
power. However, due to the large turnout at the first meeting, we decided that joining a two man
team from RIT seemed foolish if the vast majority of the effort came from the UofR. In the
excitement, we decided to set out on our own, and started work on the UR-MM1, the University of
Rochester's first attempt at building a Micro Mouse.
Over the next several months we were hard
at work planning out our design. By the time winter-break rolled around, we had gone through many
design revisions, and were ready to start construction. In February, we were just about finished
(but not quite) when we headed off to Boston, for the IEEE APEC Micro Mouse competition. It was the
first real test of our device. But alas, technical difficulties abound, we were unable to actually
run the maze (but it looked good sitting there). With a race behind us and a fresh set of new
ideas, we set to fixing and revising our mouse. In April, we set off for an IEEE contest in West-
Point. Our hard work finally paid off. Victory was ours! We came in first place (there were no other
entries, but that's irrelevant).
In April of 1993, we packed up our equiptment and headed upto
Toronto for the 2nd annual BEAM robot olympics, where we met up with our past rivals who trounced us
in Boston (Dave and Louis). As expected, Dave cleaned up with his Mitee Mice, followed closely by
the Mouse-Mobiles, but much to everyone's surprise the UR-MM1.2a, performed rather well, (it moved,
beeped, and flashed its lights) beating out several other non-functional mice, although there were
still small problems with the turning algorithm.
year, we took our updated mouse (now the UR-MM 1.3141578A) to the following BEAM competition, in
March 1994. Apperantly Dave had heard of our progress, and was too scared to show up. Louis took
first (after some technical problems with the mazes were corrected), and a suprise entry from
Queen's University took second over our third place, by judges desicion. Our performance was quite a
sight to be seen, we wandered around the maze for the full 15 minutes, covering roughly 3/4 of the
total maze area, without ever crossing into the finish cell. With thanks going to Tom Rickey of the
University public relations office, we received much media attention, including: WHAM, WXXI, UR
Currents, UR Campus Times, Rochester Review, New York Times, Toronto Globe and Mail, Mechanical
Engineering, San Fransico Examiner, etc.
Currently, the team consists of a
moderate number of students, both graduate and undergraduate, from several departments, such as
Mechanical Engineering, Electrical Engineering, Computer Science, Optics, and Physics.
experience gleaned from the current mouse design, we have been putting together a design for a new
and improved micro mouse, that we will be refining over the upcoming months, and will hopefully have
constructed before the end of the academic year. We will of course also continue with work on the
When not working on the robot itself, we are
usually trying to solicit financial support to further our progress. Currently we are recieving
contributions from the departments of Electrical Engineering, Mechanical Engineering, Computer
Science, the College of Engineering and Applied Science, and are always looking for other sources.
Please send contributions to:
The University of Rochester Micro Mouse team c/o
Dept. of Electrical Engineering
University of Rochester
Rochester, NY 14627
Thank you for your support!
UR-MM1 Implentation details
The UR-MM1's drive system
consists of two DC motors, two sets of gears, and two wheels mounted one on each side wheelchair
style. Small castors keep each end of the mouse from dragging on the floor. Mounted within the
chassis are optical shaft encoders on each of the two drive wheels. These tell how far the wheels
For wall detection, we have experimented with a number of different techniques,
including: electrostatic sonar elements, arrays of IR emitter/detectors mounted on "wings" over the
tops of the walls, linear arrays of charge coupled devices (CCDs), and several other methods.
Currently we are using sets of IR emiter/detector pairs mounted on the sides of the mouse pointing
horizontally at the sides of the walls.
The heart of the UR-MM1 is the intel 80C196KC
microcontroller. It contains many useful features on-chip, including the analog to digital
converter used for the sensors, and a serial port enabling the transfer of data and code with a host
Future Objectives Our objectives of this project are severalfold:
- To continue work on the UR-MM1.2a
- To compete in several competitions each year.
To continually come up with new ideas and implementations, modifying and improving on the previous
design, year after year.
- Design and build the UR-MM2 using the knowledge gleaned from the
experiments and experiences with the UR-MM1, while continuing the use of the UR-MM1 for competition
and experimental use.
- To expand our practical experiences and learn valuable knowledge about
microprocessor and control circuitry, efficient algorithm design, motor control, drive systems,
organizational skills, how to work with a group towards a common goal, and many other skills that
will undoubtedly come in handy later in life.
- To have FUN!!!
Jeff Weisberg (adapted
from IEEE/APEC Rules)
I. Specifications for the maze
- The maze shall
comprise 16 x 16 multiples of an 18 cm x 18 cm unit square. The walls constituting the maze shall be
5 cm high and 1.2 cm thick. Passageways between the walls shall be 16.8 cm wide. The outside wall
shall enclose the entire maze.
- The sides of the maze shall be white, and the top of the walls
shall be red. The floor of the maze shall be made of wood and finished with a non-gloss black
paint. The coating on the top and sides of the walls shall be selected to reflect infred-red light
and the coating on the floor shall absorb it.
- The start of the maze shall be located at one of
the four corners. The starting square shall have walls on three sides. The starting square
orientation shall be such that when the open wall is to the "north", outside maze walls are on the
"west" and "south". At the center of the maze shall be a large opening which is composed of 4 unit
squares. This central square shall be the destination. A red post, 20 cm high, and 2.5 cm on each
side, may be placed at the center of the large destination square if requested by the handler.
Small square posts, each 1.2 cm x 1.2 cm x 5 cm high, at the four corners of each unit are called
latice points. The maze shall be constituted such that there is at least one wall touching each
lattice point, except for the destination square.
- The dimensions of the maze shall be accurate
to within 5% or 2 cm, whichever is less. Assembly joints on the maze floor shall not incolve steps
greater than 0.5 mm. The change of slope at an assembly joint shall not be greater than 4. Gaps
between the walls of adjacent squares shal not be greater than 1 mm.
II. Specifications for the Micro Mouse
- A Micro
Mouse shall be self contained. It shall not use an energy source employing a combustion process.
- The length and width of a Micro Mouse shall be restricted to a square region of 25 cm x 25 cm.
The dimensions of a Micro Mouse which changes its geometry during a run shall never be greater than
25 cm x 25 cm. The height of a Micro Mouse is unrestricted.
- A Micro Mouse shall not leave
anything behind while negotiating the maze.
- A Micro Mouse shall not jump over, climb, scratch,
damage, or destroy the walls of the maze.
III. Rules for the Contest
The basic function of a Micro Mouse is to travel from the start square to the destination
square. This is called a run. The time it takes is called the run time. Traveling from the
destination square back to the start square is not considered a run. The total time from the first
activation of the Micro Mouse until the start of each run is also mesured. This is called the maze
time. If a mouse requires manual assistance at any time during the contest it is considered touched.
By using these three parameters the scoring of the contest is designed to reward speed, efficiency
of maze solving, and self-reliance of the Micro Mouse.
- The scoring of a Micro Mouse shall
be done by computing a handicapped time for each run. This shall be calculated by adding the time
for each run to 30 of the maze time associated with that run and subtracting a 10 second bonus if
the Micro Mouse has not been touched yet1. 1 For example assume a Micro Mouse, after being on
the maze for 4 minutes without being touched, starts a run which takes 20 seconds; the run will have
a handicapped time of:
The run with the fastest handicapped time for each Micro Mouse shall be the offical time of
that Micro Mouse.
- Each contesting Micro Mouse shall be subject to a time limit of 15 minutes
on the maze. Within this time limit, the Micro Mouse may make as many runs as possible.
the Micro Mouse reaches the maze center it may be manually lifted out and restarted or it may make
its own way back to the start square. Manually lifting it out shall be considered touching the Micro
Mouse and will cause it to loose the 10 second bonus on all further runs.
- The time for each
run shall be measured from the moment the Micro Mouse leaves the start square until it enters the
finish square. The total time on the maze shall be measured from the time the Micro Mouse is first
activated. The mouse does not have to move when it is first activated but it must be positioned in
the start square ready to run.
- The time taken to negotiate the maze shall be measured either
manually by the contest officials or by infra-red sensors set at the start and destination. If
infra-red sensors are used, the start sensor shall be positioned at the boundary between the start
square and the next unit square. The destination sensor shall be placed at the entrance to the
destination square. The infra-red beam of each sensor shall be horizontal and positioned
approximately 1 cm above the floor.
- The starting procedure of the Micro Mouse shall not offer
a choice of strategies to the handler.
- Once the maze configuration for the contest is
disclosed, the operator shall not feed the Micro Mouse with any maze information.
illumination, temperature, and humidity of the room in which the maze is located shall be those of
an ambient enviornment. Requests to adjust the illumination may be accepted at the discretion of the
- If a Micro Mouse appears to be malfunctioning, the handlers may ask the
judges for permission to abandon the run and restart the Micro Mouse at the beginning. A Micro Mouse
shall not be re-started merely because it has taken a wrong turn.
- If a Micro Mouse team elects
to stop because of technical problems, the judges may, at their discretion, permit the team to run
again later in the contest with a 3 minute maze time penalty1. 1 For example, assume a Micro
Mouse is stopped after 4 minutes; it must be restarted as if it had already run for 7 minutes, and
will have only 8 more minutes to run.
- If any part of a Micro Mouse is replaced during
its performance, such as batteries or EPROMS, or if any significant adjustment is made, the memory
of the maze within the Micro Mouse shall be erased before restarting. Slight adjustments, such as to
the sensors may be allowed at the discretion of the judges, but operation of speed or strategy
controls is expressly forbidden without a memory erasure.
- No part of the Micro Mouse (with the
possible excpetion of batteries) shall be transferred to another Micro Mouse. For example if one
chassis is used with two alternative controllers, then they are the same Micro Mouse and must
perform within a single 15 minute allocation. The memory must be cleared with the change of a
- The contest officials shall reserve the right to stop a run, or disqualify a Micro
Mouse, if they believe its continued operation is endangering the condition of the maze.