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