Computerized Labyrinth Solver

1
Computerized Labyrinth Solver

• Gregory Schallert
• Chad Craw

2
System Overview

• Motors Control Playing Platform by Video
  feedback.
• Video processing is done by the PC
• Motor control is done by the HC12

3
User Interface

• Minimal amount of buttons and LEDs
• The interface shall report current operating
  status, and any encountered errors through LED
  codes

4
User Interface
5
System Test on Startup

• The system will rotate the maze surface a maximum
  deflection on both axes
• All status and Error LEDs will flash in unison to
  make sure the are operational
• The system will analyze the current maze
  structure, and output a binary stream
  representing the wall placements as well as
  values of the current X and Y axis rotation to
  the Serial interface.

6
Dynamic Maze Construction

• Maze walls are placed in arbitrary positions to
  create a new maze each time.
• Limited Start and End Tags are placed along the
  outer edge of the wall

7
Maze Construction Diagrams
Wall Slot
Maze Surface
Contact Nodes
8
Maze Scanning Phase

• An array of multiplexers are attached to the
  contact nodes of each wall slot.
• These connections are scanned synchronously by
  the HC12 board to determine positions of walls.
• Once this scan is complete, the virtual maze is
  passed to the connected PC via the serial
  interface to start the maze solving algorithm.

0010000111 0101001111 0111101101 0110111100 101010
0001 0001000101 1111001010 0010100111 1001011100 A
ng X 1.2 Ang Y 5.5 X Pos01 Y Pos54
9
Lee Moore Algorithm

• Inputs Walls, Start and End Points.
• Output Finds the a path from start to finish.
• Each cell is given a value of -1.
• Starting Cell is given a value of 0
• If we have not reached the end, set the current
  cell to the highest value not yet used.
• Each cell touching the current cell with a -1 has
  the value of this cell 1
• Check each cell to see if we are at the end
• If not, continue

10
Video Capture

• Use the CCD Camera to find ball location
• Compare the current location to the desired path
• Send the offset to the next goal to the serial
  interface

11
The Camera

• Logitech QuickCam CCD Camera
• 352x288 Maximum True Resolution
• 30 Frames/sec
• 25cm/120 2mm grid
• 25cm/288 lt 1mm grid
• We want 4mm resolution
• MEANS WE ARE GOOD TO GO

12
The Software

• OpenCV
• Video Tracking algorithms
• DirectShow
• Video Capture Filters
• Logitech SDK
• Camera Calibration and Windows Drivers
• All of the Software is Free and Documented

13
The Process

• DirectShow captures the video input
• The OpenCV algorithms are applied to track the
  object
• The information is sent to the HC12
• Any additional text overlays are added and
  rendered to the screen

14
A System Model

• Sum the masses
• Sum the Torques
• Solve for acceleration
• This relates the acceleration to the angle of the
  platform

15
A System Model (cont)

• Take two snapshots
• One at the zero position
• One after some time
• Note R and d stay constant
• Use law of cosines to solve for the angle
• This relates the acceleration to the distance the
  control axle at r has turned

• Can also solve for vertical displacement

16
Control System

• The algorithms for the control system shall
  operate on the HC12 board.
• The system will collect feedback data from the
  Video tracking algorithm on the PC via the Serial
  Interface of the HC12 board
• This data shall be sent as a 3-byte packet at
  every sample interval of the tracking system
• It shall contain a signal start byte (to maintain
  alignment), followed by 2 data bytes for the
  current X and Y offsets
• The position of the ball while traversing the
  maze shall be maintained with a Fuzzy Logic
  Control system.
• The only data that needs to be collected from the
  PC Video tracking system is the balls current
  offset from its target position

17
Control System

• The FLC will use a rule set based on 5 states of
  the system
• The ball is far to the left(top) of its target
  position
• The ball is near to the left(top) of its target
  position
• The ball is at its target position
• The ball is near to the right(bottom) of its
  target position
• The ball is far to the right(bottom) of its
  target position
• These rules shall be applied symmetrically to
  both the X and Y axes of the balls position.
• Using this rule-set, the control system shall
  derive the angular rotation necessary to move the
  ball in the desired direction at the desired
  speed.

18
Control System (Pathfinder)
Y offset 0 X offset 10
Y offset 0 X offset 0
Y
Y offset 10 X offset 0
X
Y offset 20 X offset 0
End
Start
19
Motor Control

• Each motor shall be attached to the actuators of
  each axis, and shall operate independently of one
  another.
• The operation of each motor is identical due to
  the symmetrical nature of the maze surface.

20
Motor Specs

• SL561 Standard, BB
• Size
• Length 1.51
• Width 0.73
• Height 1.37
• Torque 46.1 oz
• Speed 0.18 sec/60
• Weight 1.50 oz
• Voltage 4.8V 6V

21
Possible Errors

• Nonlinear elements of the system
• Fuzzy Logic Control
• Keep speed Down
• Video Resolution/timing
• Damp the system
• Keep speed Down

22
Conclusion