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Matttmouse 2


Some links I find useful:

Micromouse Info Micromouse at the TIC Micromouse Information Centre
Royal Holloway Micromouse design group Micromouse at Royal Holloway London PIC Programming Tutorial


This page is about the robot I am currently working on. It is a maze solving robot, built to the Micromouse competition rules.

Basically, I thought making a Micromouse sounded like an interesting challenge.


Hardware


The robot is constructed from several boards, held together with stand-offs. The bottom two layers have the two servos mounted between them which provide drive for the robot using improvised Lego wheels. The servos are bolted onto two 10x25x75mm aluminium blocks.


The top of the servos
The base of the chassis, showing servos, Lego wheels, aluminium blocks and veroboard Layers


The bottom of the servos
The base of the chassis, showing the skids


The next layer has the four sensor boards bolted onto it. Each one comprises of 5 pairs of SFH409 IR emitters and SFH309 phototransistors.


The first two layers of the robot
The third level, showing the mounting of the sensor arms


The top of one of the sensors
One of the sensors


The bottom of one of the sensors
The other side of the sensor, showing the layout of the IR LEDs


A circuit diagram of the sensor
The sensor circuit


A diagram showing how the sensors sense the wall
Just to clarify how the sensors work, a diagram


The next layer is the main processing board. It basically consists of a Microchip PIC16F877A microcontroller, currently running at 4MHz, and a load of molex connectors. It is a slightly modified version of Nigel Goodwin's third "Main Board".


The top of the processor board
The main processor board


The bottom of the processor board
The bottom of the main processor board


The next layer is what I call the "Connector Board". It basically connects each of the parts of the robot to the PIC16F877A's 31 I/O pins. The Microchip 26LC64 EEPROM chip is also on this board.


The connector board
The "Connector Board" (Currently incomplete)


The bottom of the connector board
The bottom of the "Connector Board" (Currently incomplete)


The next layer has a load of switches on it. The first toggle is the power switch. The remaining five connect 9 I/0 pins to either: the DIL switches, the LCD, or the "Debugging Board". The DIL switches and the push button allow me to select different modes. The LCD is also bolted onto this board. Bellow the LCD is the battery monitors. They are copied from Cybot. Info on Nigel Goodwin's website here. The red bit of wire is a loop for lifting the robot (as stated in the rules).


The 'switchboard'
The "Switch Board"


Another picture of the 'switchboard'
Another view of the "Switch Board"


The bottom of the 'switchboard'
The bottom of the "Switch Board"


The robot is powered by eight 2000mAh AA NiMH batteries, providing two ~5v supplies, one for the microprocessor and sensors, and one for the servos.


A view of the whole robot
The whole robot


Software


The mouse successfully works as a wall follower, but I found the servo motors used to be too slow to work as a competitive maze solver, so I have started on a second robot, which will be a maze solver. The maze would have been stored in the EEPROM, as the mouse systematically runs around the whole maze. It would have then used the flood-fill method to solve the maze, and will then take a timed run to the center.


Updates


Sometime in 2004 - Found the Micromouse competition rules

September 2004 - Decided to build a mouse and purchased servos and aluminium

October 2004 - Built sensor arms and first 3 levels of the chassis

November/December 2004 - Got coding for LCD, servos and sensors working

15/16th January 2005 - Built the main processing board and connector board

17th January 2005 - Got coding for LCD, servos, servos and EEPROM working with new hardware (not on breadboards)

14th February 2005 - Cut some of the parts for the maze. Fixed some problems with the hardware. Got the LCD working forwards this time (data lines reversed). Took some low resolution photos.

10th March 2005 - Got the robot to follow a wall successfully

3rd April 2005 - Over the past week I have been working on the mouse overtime for the MINOS competition (10th April 2005). The mouse can now so left and right 90 degree turns. I have removed the Lego blocks from the wheels to make the robot less wide. I mouse now hits the maze wall less. :)

6th April 2005 - The mouse can now successfully navigate a test maze for about half an hour without hitting a wall.

9th April 2005 - The MINOS competition. Matttmouse came last by far (3mins compared to <1min for the other mice), but made it to the centre of the maze without human intervention.

11th June 2005 - The Micromouse competiton. Matttmouse came last in the heats, performing the same as at MINOS. A broken wire on the front sensor meant that I did not take part in the finals.

12th June 2005 - I have decided to scrap Matttmouse as the servos are far too slow and to create a new mouse using stepper motors. See my new micromouse page for details.


Specification


A dot Name: MatttMouse (MatttCattt -> MatttMouse :D )
A dot Propulsion: Two RC Servos (Futaba S3003) hacked for full rotation
A dot Power: Six AA NiHM 2000mAh batteries, providing about 7.2v, which is regulated down to 5v
A dot Sensors: Five pairs of SFH409 and SFH309 IR emitters and phototransistors respectively, on each arm (front, back, left and right)
A dot Processing: One Microchip PIC16F877A, running at 20MHz
A dot Debugging: One Optrex DMC16433 4x16 LCD
A dot Weight: ~850g
A dot Speed: About 0.05 m/s