Quester - Retired

A micromouse, which uses vision to detect the walls of the maze, segmented bump sensors in case it doesn't, and a layered behaviour control program.
Finalist in the Robotics Age "Home Robot Photo Contest". Article in Robotics Age Jan/Feb 1982.
Photograph of Quester used to illustrate an article on mobile robots, p641, The Home Computer Advanced Course #33, 1984.
Photograph - Scale Models International, April 1988, p207.
Built June 1981 -.
Size - 8" * 5 1/2" * 7 1/2".
Operational area - 3ft * 3ft using a small maze.
# Technical overview

1981 - Quester took part in the Wembley heats of the July 1981 Amazing Micromouse Contest
1981 - Paris, September 7-10, Quester took part in the EUROMICRO competition
1982 - David L Buckley won third prize in the schools competition of the Euromouse Maze Contest
A £25 computer book voucher from McGraw Hill
1983 - David L Buckley's mouse Quester won 4th prize in the 1983 finals at Earles Court, Novice Section

1981		1982		1983

1996 - Quester won the 'Thezeus Award 1996' created and presented by Alan Dibley.

Technical overview:

• Quester has a differentially steered base with quadrature shaft encoders in each wheel gear train.
• Light from subminiature LEDs (the size of SMT ones) shines through holes cut in the gearwheels and detected by phototransistors.
• The phototransistors feed into hardware logic quadrature decoder counters which are read by the control computer.
• There is a forward facing Ultrasonic Tx/Rx sensor pair activated and read by the control computer.
• There are four wire loop bump detectors (a bit like Shakey) which feed into a CMOS logic Reactive subsystem.
  • the Reactive subsystem uses resistor/capacitor delays to sequence commands to the motor drivers for avoidance action.
    ( As Mark Tilden used later for Beam robots. )
• There are two compound eyes built with phototransistors, each with three auto iris pixels.
  • The acceptance angle of each pixel is about 5 deg.
  • The auto irises have about 4 times the acceptance angle of the associated pixel.
  • One pixel of each eye is set to detect side openings to a maze corridor.
  • One pixel of each eye, looking slightly down, is set to detect a wall in front.
    • The front pixel can be used to detect the distance from the wall by sensing the transition from black to white as the wall is approached.
  • One pixel of each eye is used for guidance and is aimed out and down at the baseboard just by the sidewall about 6 inches in front of the robot.
    • detecting the light dark transition allows Quester to be steered down a maze corridor.
  • Using the front facing pixel or the guidance pixel of each eye Quester can square up to a wall.
• The Brain is a 6502 control board with a 512 byte Monitor, 1K RAM, a LED readout, hex keypad and tape interface and cost today's equivalent of a high-end desktop PC.
  • The computer was programmed in hex from hand assembled code and programs saved to tape.
  • The computer has direct control of the motors and Ultrasonic sensor.
  • The computer can read the eye receptors and the shaft encoder counters.
  • Using the shaft encoder counts and a PI error loop (no D) turns can be made to about 6 degrees which is enough for orientation in the maze.
  • Using the shaft encoder counts and a PI error loop (no D) distance can be measured to about 1/4 inch which is enough to count maze cells.
  • Using the information from the guidance pixels and a PI error loop (no D) the robot can steer down a maze corridor.
• The control computer can read and override the hardware Reactive subsystem. ( very important! )

References:

• Scale Models International, Argus Press, Hemel Hempstead.
• The Home Computer Advanced Course, Orbis Publishing Ltd, London (Published in Europe, South Africa, New Zealand, and Australia).

See also Micromouse - the early years