Automated Maze System Development
Group 9Tanvir HaqueSidd MurthySamar Shah
Advisors: Dr. Herbert Y. Meltzer, PsychiatryDr. Paul King, Biomedical Engineering
Introduction
Microdialysis Method of
measuring physiological activity during task
Dr. Meltzer’s Lab uses it to study brain activity during memory tasks
Experimental Setup
Rat hooked up to Microdialysis
Rat placed in Maze, performs memory tasks
Sample collected during maze run
Sample Analyzed for content
Problems
Dialysis tubes’ entanglement
Rat’s recognition of overhead device psychological
repercussions Manual guiding of
tubes cumbersome for researcher
Constraints
Maze Dimensions Rat Size Rat Speed Rat Cognition Tube Length Dialysis Weight
Depth: 18”
Primary Objective
To develop a fully independent research module that facilitates the study of memory
System Description
Acquire Mouse Position
Determine Change
in Position
Translate Dialysis Machine
Position Acquisition
Method Pros Cons
Camera High Resolution Real-Time feedback Software intensive
Mounting Issues Processing Limitations$1,355
Sensor Manageable data Less processing$1,160
Low resolution Center of maze difficult to map
Image Processing
Acquire Image Calibrate the Image
Convert the 32 bit image to an 8 bit image
Filter Image 1: Remove Border Objects
Filter Image 2: Remove Small Objects
Pattern Match to a Specified Image
Determine the pixel at the center of the pattern
Translate pixel value into physical coordinates
Output Physical coordinates in array form
LabVIEW Software Code
Image Processing
Unprocessed Image Processed Image
LabVIEW Screen Shot
Choosing a Microprocessor
Motorola 68HC11E One 8-bit input Low cost On board A to D
converter $200
NI PCI-7342 Four 8-bit inputs More processing
capabilities Software
Compatibility with LabView
$895
Processing the Information
Continually Given one set of coordinates (X,Y)
Compares the coordinates of (Xn-1,Yn-1) to (Xn,Yn), computes the difference, and rounds the significant digits
Converts the difference into specified timed waveform for the driver
Driver amplifies signal and controls motor speeds
Drive System
Lead-screw Device Easy to build Inefficient $1,576.72
Pulley/Belt System Complicated System Efficient $6,000
The Lead-Screw Device
• Motor Driven
• Rotational Energy converted to Linear Energy
Device Apparatus
Device Apparatus
• Driven by dual motor system
• Translation responds to mouse movements
• Open Loop Feedback
Choosing a Motor
Design Considerations: Speed of Mouse: 2 ft/s Torque
Torque needed to drive apparatus Torque needed to provide acceleration
Stepper Motor or DC Motor?
Speed
Lead (in/rev) RPM
.125 11520
.25 5760
.5 2880
RPM = 25.5 in/s / Lead*60 s/min
Target RPM Range 3000 -12000
Torque
Driving Torque Driving Torque
Acceleration
Driving Torque
2 ft/s I
L = 2.37 lbsP = .5 in/revef= .4 (for ACME)
Tf = 53 mNm
Posi
tion
Time
25 in
-25 in
I = 0.001207 lb-in-s2
α = 265 rad/s2
T = 36 mNm
Worst Case Scenario
Stepper or DC?
Stepper Torque < 3.53 Nm RPM < 2000
DC High Torque High RPM
DC Motor
3000 RPM (using 0.5 lead)
87 mNm Torque Powered by Driver Monitored by
external Optical Encoder
Flow Chart
Image Calculate Δ(x,y)
Micro-Processor
DriverMotor Translation
Image Calculate Δ(x,y)
Micro-Processor
DriverMotor Translation
Budget
Support Scaffolding $99.70
Mechanical Arm (including driver electronics)
$1576.72
Microcontroller $895.00
Labview/Imaging Software $1,355.00
Grand Total $3926.42
Departmental Reconsiderations
Budget limitations caused the psychiatry department to reconsider the value of their experimental setup.
Thus, our design, though it was considered valuable by the department, was not approved.
Contingency plan
Develop a model which represents fundamental principles of design
Image acquisition system demonstration – LabVIEW software
Mechanical arm system demonstration – Erector set
Overall Status
Developing Theoretical Model Next step: Final Report and Poster Board
Month/Tasks January February March April
Breakdown of parts needed
Researched parts and obtained quotes
Offer proposal for parts
Develop theoretical model
Build theoretical model
Work on Poster Board
Work on Final Report
Conclusion
Though no tangible design will be developed, a better understanding of image acquisition systems, micro-processing and linear actuators was obtained
With the development of the theoretical model, the perceived design was realized and used for its educational purposes