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

Sensor Manageable data Less processing

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

NI PCI-7342 Four 8-bit inputs More processing

capabilities Software

Compatibility with LabView

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 Relatively Easy to build Not very efficient Cheap

Pulley/Belt System Complicated System Efficient Expensive Mounting Issues

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: roughly 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 the experiment

Design was put on hold until further notice

Contingency plan

Develop a model which represents fundamental principles of design

Image acquisition system – LabVIEW software

Mechanical arm system – Erector set

Overall Status

Project on hold Next step: Develop Theoretical Model

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