Transcript Midsemester Presentation

Team Members:
Heather Waldeck
Meghan Olson
Andrea Zelisko
Yao Lu
Ben Sprague
Missy Haehn
Advisor:
Professor John
Webster
Client:
Matthew I. Banks, Ph.D.
Department of
Anesthesiology
University of Wisconsin
To develop a lightweight device to
measure the position of a mouse
head. The device would be used during
an experiment and must not interfere
with the testing.
•Sound waves elicit vibrations in cochlea
•The basilar membrane transfers sound
waves into neural signals.
•If sound is repeated we learn the
frequency pattern and can recognize that
sound
•Sound location determined from wave
phase and time differences.
•Different sounds trigger different neural pathways.
•Neural pathways are crucial in sound perception.
• GABAA receptors facilitate inhibition of neural
excitation.
• Inhibitory activities play important role in
perception and cognition of auditory stimuli.
• Our client studies perception and cognition of
auditory system in mice.
•Measures brain waves of mice in response to
sound stimuli.
• Position and orientation of head relative to
speaker will affect brain activity
• Specifically studying the effects of drugs on
perception and cognition in mice
• <$5,000
• Does not interfere with current equipment
• <1 gram on head
• Does not pose danger to mouse and testers
• Must work with in conditions of cage
• Easy to use (minimal calibration)
• < 1 cm x 1 cm
Presenters: Meghan Olson
Ben Sprague
Overview
•Design Options
•Optical
•Ultrasonic
•Magnetic
•Design Matrix
•Proposed Design
•Polaris Development Kit
•2 wireless infrared light emitters placed
strategically placed on head
•Infrared light sensor placed outside cage,
within line of sight of entire cage
•Sensor connected to computer,
interpreting signal with designed software
•Easy system to use with well developed software
•Little adjustment of product to make it work in
this design setting
•Wireless emitters of light, so less restricting on
subject
•Expensive in comparison to other designs
•Require line of sight between emitters and
sensor at all times
•Continual improvements and updates to
technology continuing
• Two transmitters on head, at least three
receivers around cage
• Voltage or time measured at receivers
• Can calculate distance from receivers
• Can calculate angle from two signals of the
head
• Operates in a reasonable frequency (40 kHz)
• Cost efficient
• Feasible
• Gives position and orientation
• Interference from bouncing signals
• Not light enough
• May be difficult to process signals
• Magnetic fields will produce current in wire
• Use Honeywell sensors
• ± 90° and ± 45 °
• ~$5 each
• Have sensor grid underneath cage
• Two or Three small magnets on the mouse head
• Measure magnitude of voltage
• Need amplifier circuits
• Lightweight
• Cost effective
• Easy to use
• No wires on mouse
• May affect/affected by existing instrumentation
• Positioning algorithm
• Affect brain sensors or mouse?
Design Options
Feasibility
Size/Weight
Cost
Ease of Use
Total
Ultrasonic
3
1
2
1
7
Magnetic
1
2
1
3
7
Infrared
3
3
2
2
10
• How many sensors?
• Where to position sensors and magnets (how far
apart?)
• How does mouse movement affect voltage readings
• How to connect to computer
• Parallel Port
• Interface
•NDI. http://www.ndigital.com/polaris.html.
October 2nd, 2003
•Mass – Air/ Ultrasonic. http://www.massa.com/air_products.htm.
September 29, 2003.
• Honeywell SSEC.
http://www.ssec.honeywell.com/magnetic/products.html.
October 4, 2003.
Design Team 2

Presenters
Missy Haehn
 Heather Waldeck


Outline of Design Options
Magnetic Sphere
 LED
 Electrical Potential

Option 1: Magnetic Ball

How it works




Sphere with magnet is on
mouse head
Lengthening and direction
of force correlates with
position
Ability to measure
orientation
Disadvantages


Calibration needed
Weight
Option 2: LED
How it works:




Sound for exp. is emitted and the LED pulses
Pulse detected by light sensors (receiver)
Position determined by sensors
Voltage output generated for analyzation
Disadvantages:
Precise, but 2-D position
 Light sensors must
surround entire cage

Option 3: Electric Potential

How it works


3 conducting spheres with specific
charges and positions above mouse
head
Measure electric potential



V = ke( q1/r1 + q2/r2 + q3/r3 )
Ability to measure head orientation
Disadvantages


Interference
Need additional known variable
Evaluation Grid
Magnetic
Ball
LED
Electric
Potential
Weight
Very Heavy
Light
Moderate
Precision
3-D
2-D
3-D
Cost
Moderate
High
Low
Interference
Moderately
Low
None
High
Safety
Moderately
Unsafe
Very safe
Moderately
safe
Final Choice:
Electric Potential + LED



Magnetic Ball design too heavy
LED design only produced 2-D position
Electric Potential design had too many unknowns to
solve
Solution: Combine Electric Potential with LED



3 different known charges and an LED on mouse’s
head
Voltmeter and light sensors together determine
position and orientation of mouse’s head
Two methods of sensing result in accurate, 3-D data
Future Work

Reduce interference


Investigate and test sensors


Voltmeter and light
Determine appropriate charges


Insulation
Create appropriate electrical potential
Find way to correlate different voltages

Software
Design Team 3

Presenters
Yao Lu
 Andrea Zelisko


Design Overview
Acoustic (Ultrasound) Tracking
 Optical Tracking
 Magnetic Tracking

Acoustic (Ultrasound) Tracking

Direct Measurement


Two transmitters


Time-of-flight
Different frequency
Three receivers for
each transmitter
(Auer et al)
Optical Tracking
Four passive LEDs
 Camera in fixed location
 External Infrared source
 Continuous tracking (position, orientation)

(Baratoff andBlanksteen)
External
Infrared
Source
Illumination
Mouse’s Head
with four
passive LEDs
Reflection
Camera
Magnetic Tracking



Source composed of 3 coils of wire
perpendicular to each other.
Magnetic field due to coils.
Sensor detects strength of field.
(“Sensing in VR”)
Design Matrix
Interference
Sources
Ease to
Manufacture
Accuracy
weight
Interference
with Data
Overall Score
Acoustic
(Ultrasound)
3
Optical
1
3
2
2
1
3
3
1
2
2
3
1
9
13
7
2
Electromagnetic
1
Proposed Design: Optical

Advantages:
 Lightweight
 Does
not interfere with brain wave recording
 Easiest to assemble

Potential Problem:
 Output
data may be interfered by obstruction in
line of sight.
 Solved by ensuring camera cannot be blocked.
Future Works
Research and finalize the proposed design
 Decide on components
 Build device
 Test device

References

Barafoff, G., Blanksteen, S. “Tracking Devices.” Accessed: September 29,
2003. URL:
http://www.hitl.washington.edu/scivw/EVE/I.D.1.b.TrackingDevices.html

Auer, V., Bonfim, M.J.C., Lamar M.V., Maes M.M., Wanderley M.M. “3D
Positioning Acquisition System with Application in Real-Time Processing.”
Accessed: October 1, 2003. URL: http://www.ircam.fr/equipes/analysesynthese/wanderle/gestes/externe/ICSPAT96.pdf

“Sensing in VR”. Accessed September 17th, 2003. URL
http://www.cybertherapy.info/pages/sensing.htm.