Heather Waldeck Meghan Olson Andrea Zelisko Yao Lu Ben Sprague Missy Haehn Team Members:

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 cochleaSound waves elicit vibrations in cochlea The basilar membrane transfers sound waves into neural signals.The basilar membrane transfers sound waves into neural signals. If sound is repeated we learn the frequency pattern and can recognize that soundIf sound is repeated we learn the frequency pattern and can recognize that sound Sound location determined from wave phase and time differences.Sound location determined from wave phase and time differences.

Different sounds trigger different neural pathways.Different sounds trigger different neural pathways. Neural pathways are crucial in sound perception.Neural pathways are crucial in sound perception. GABAA receptors facilitate inhibition of neural excitation. GABAA receptors facilitate inhibition of neural excitation. Inhibitory activities play important role in perception and cognition of auditory stimuli. Inhibitory activities play important role in perception and cognition of auditory stimuli.

Our client studies perception and cognition of auditory system in mice. Our client studies perception and cognition of auditory system in mice. Measures brain waves of mice in response to sound stimuli.Measures brain waves of mice in response to sound stimuli. Position and orientation of head relative to speaker will affect brain activity Position and orientation of head relative to speaker will affect brain activity Specifically studying the effects of drugs on perception and cognition in mice 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 FeasibilitySize/WeightCost Ease of Use Ultrasonic3121 Magnetic1213 Infrared3322Total7 7 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. October 2 nd, 2003 Mass – Air/ Ultrasonic. September 29, Honeywell SSEC. October 4,

Design Team 2 Presenters Presenters Missy Haehn Missy Haehn Heather Waldeck Heather Waldeck Outline of Design Options Outline of Design Options Magnetic Sphere Magnetic Sphere LED LED Electrical Potential Electrical Potential

Option 1: Magnetic Ball How it works How it works Sphere with magnet is on mouse head Sphere with magnet is on mouse head Lengthening and direction of force correlates with position Lengthening and direction of force correlates with position Ability to measure orientation Ability to measure orientation Disadvantages Disadvantages Calibration needed Calibration needed Weight Weight

Option 2: LED How it works: Sound for exp. is emitted and the LED pulses Sound for exp. is emitted and the LED pulses Pulse detected by light sensors (receiver) Pulse detected by light sensors (receiver) Position determined by sensors Position determined by sensors Voltage output generated for analyzation Voltage output generated for analyzationDisadvantages: Precise, but 2-D position Precise, but 2-D position Light sensors must Light sensors must surround entire cage

Option 3: Electric Potential How it works How it works 3 conducting spheres with specific charges and positions above mouse head 3 conducting spheres with specific charges and positions above mouse head Measure electric potential Measure electric potential V = ke( q1/r1 + q2/r2 + q3/r3 ) V = ke( q1/r1 + q2/r2 + q3/r3 ) Ability to measure head orientation Ability to measure head orientation Disadvantages Disadvantages Interference Interference Need additional known variable Need additional known variable

Evaluation Grid Magnetic Ball LED Electric Potential Weight Very Heavy LightModerate Precision3-D2-D3-D CostModerateHighLow Interference Moderately Low NoneHigh Safety Moderately Unsafe Very safe Moderatelysafe

Final Choice: Electric Potential + LED Magnetic Ball design too heavy Magnetic Ball design too heavy LED design only produced 2-D position LED design only produced 2-D position Electric Potential design had too many unknowns to solve 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 3 different known charges and an LED on mouse’s head Voltmeter and light sensors together determine position and orientation of 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 Two methods of sensing result in accurate, 3-D data

Future Work Reduce interference Reduce interference Insulation Insulation Investigate and test sensors Investigate and test sensors Voltmeter and light Voltmeter and light Determine appropriate charges Determine appropriate charges Create appropriate electrical potential Create appropriate electrical potential Find way to correlate different voltages Find way to correlate different voltages Software Software

Design Team 3 Presenters Presenters Yao Lu Yao Lu Andrea Zelisko Andrea Zelisko Design Overview Design Overview Acoustic (Ultrasound) Tracking Acoustic (Ultrasound) Tracking Optical Tracking Optical Tracking Magnetic Tracking Magnetic Tracking

Acoustic (Ultrasound) Tracking Direct Measurement Direct Measurement Time-of-flight Time-of-flight Two transmitters Two transmitters Different frequency Different frequency Three receivers for each transmitter Three receivers for each transmitter (Auer et al)

Optical Tracking Four passive LEDs Four passive LEDs Camera in fixed location Camera in fixed location External Infrared source External Infrared source Continuous tracking (position, orientation) Continuous tracking (position, orientation) External Infrared Source Illumination Mouse’s Head with four passive LEDs Reflection Camera (Baratoff andBlanksteen)

Magnetic Tracking Source composed of 3 coils of wire perpendicular to each other. Source composed of 3 coils of wire perpendicular to each other. Magnetic field due to coils. Magnetic field due to coils. Sensor detects strength of field. Sensor detects strength of field. (“Sensing in VR”)

Design Matrix Acoustic (Ultrasound) OpticalElectro- magnetic Interference Sources 321 Ease to Manufacture 132 Accuracy231 weight132 Interference with Data 231 Overall Score9137

Proposed Design: Optical Advantages: Advantages: Lightweight Lightweight Does not interfere with brain wave recording Does not interfere with brain wave recording Easiest to assemble Easiest to assemble Potential Problem: Potential Problem: Output data may be interfered by obstruction in line of sight. Output data may be interfered by obstruction in line of sight. Solved by ensuring camera cannot be blocked. Solved by ensuring camera cannot be blocked.

Future Works Research and finalize the proposed design Research and finalize the proposed design Decide on components Decide on components Build device Build device Test device Test device

References Barafoff, G., Blanksteen, S. “Tracking Devices.” Accessed: September 29, URL: Barafoff, G., Blanksteen, S. “Tracking Devices.” Accessed: September 29, URL: 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, URL: synthese/wanderle/gestes/externe/ICSPAT96.pdf 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, URL: synthese/wanderle/gestes/externe/ICSPAT96.pdf “Sensing in VR”. Accessed September 17th, URL “Sensing in VR”. Accessed September 17th, URL