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Mid-Semester Design PresentationSenior Design Presentation
October 8, 2009
Contactless Angular Position Sensor
Team Members
Eugene SandbergComputer Engineer
Tasks:-Construct Test Setup-Program Microchip-Website
Christine BrattonElectrical Engineer
Tasks:-Research Magnets and Sensors-Program Microchip-Output Stage
Aram LeeElectrical Engineer
Tasks:-Research Magnets and Sensors-Program Microchip
Jeremy LewisComputer Engineer
Tasks:-Construct Test Setup-Packaging-Layout
Matt LandryElectrical Engineer
Tasks:-Research Magnets and Sensors-Output Stage-Packaging
Outline
• Problem Statement• Solution Diagram• Constraints
– Technical– Practical
• Alternatives to Original Solution• Progress
– Timeline
Problem
Endcap/SensorA-Arm
Problem With Current Design
The current sensor fails often. The Army believes that it is due to the mechanical contact.
Solution - Hall Effect Sensor
Overview of Proposed Solution
Magnet
• Generates a magnetic
field.
Sensor
• Outputs a signal relative
to angular position of magnetic
field.
Microprocessor
• Processes the signal from the sensor.
DAC/Amp
• Outputs analog
voltage. (0-24V)
Constraints
• Technical Constraints
• Practical Constraints
Technical Constraints
• The CAPS must be driven by a 24 volt input and output a linear DC voltage ranging from 0 to 24 V.
• The CAPS must draw less than 24 mA.
• The CAPS must have a response time of less than 20ms or less.
Technical Constraints
• The CAPS must operate between -40 to 70 degrees Celsius
• The CAPS must be accurate to .1 degrees and measure an angle of 90 degrees.
Practical Constraints
• Problem• Sustainability
– The CAPS must be contactless.
Practical Constraints
• Problem• Compatibility
– Must Fit in End Cap – Same Casing
• Optical-Grease Interference-Outside of Vehicle-Particle Interference
Alternatives for Angular Position Sensing
• Hall Effect Sensor-No particle interference-Operates in Endcap-Sensitive to Magnetic field
Alternatives for Angular Position Sensing
Alternatives
Angular Position Sensors
MLX90316• Hall Technology• Digital SPI Output• Specify Default Mode when Ordering• Currently Being Tested• 360 Degree Range
KMA200• Magnetoresistive• Analog and Digital SPI Output• Default Mode is Analog• Will be used for Initial Testing,
Calibration of Test Setup• 180 Degree Range
Progress - Parts
MAX5312EAE• DAC• 0V-8V Output• 12Bit Percision
LM7321MA• OP AMP• 3 to 1 Amplification• Will output voltage of 0- 24• 24V supply
PIC24• Process Sensor Signal• Talks to the
MAX5312EAE
Progress-Test Setup
Test Setup
Progress
Magnet A (Largest Magnet)
Voltage at 45 Degrees Voltage at 90 Degrees Voltage at 135 Degrees
5mm 1.08 2.5 3.64
10mm 1.07 2.49 3.67
15mm 1.08 2.52 3.66
20mm 1.09 2.48 3.62
25mm 1.09 2.48 3.61
30mm 1.1 2.4 3.61
Magnet Evaluation
Progress
Timeline
Research Sensor and Magnets
Construct Test Setup
Evaluate Angle Sensor 1
Output Stage
Investigate 3D CAD Packaging
Evaluate Angle Sensor 2
Interface with Microprocessor
Package Design
8/18 8/28 9/7 9/17 9/27 10/7 10/17 10/27
References
• Karahalis, Alex. “Contacless Angular Position Sensor.” August 11, 2009.
• SPG Media Group Ltd. “Stryker 8-Wheel Drive Armoured Combat Vehicles, USA.” 2009. [Online]. Available: http://www.army-technology.com/projects/stryker/ [Accessed: August 30, 2009].
• Quasdorf, Joachim. “A Case Study: MR vs. Hall Effect for Position Sensing.” [Online]. Available: http://www.sensorsmag.com/sensors/article/ [Accessed: October 2009].
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Questions