Lab4 Sec3 Team4 Presentation Edited for Blog

8/14/2019 Lab4 Sec3 Team4 Presentation Edited for Blog

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Using an acceleromter to

explore a virtual world


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BackgroundMicro Electro Mechanical Systems (MEMS) Accelerometer

Principles

Operated under Newtons 1st Law

F = ma = kx

Under an applied acceleration, the beam deflection is

measured and the acceleration is determined


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BackgroundAnalog Devices ADLX203 Accelerometer

The circuitry in the accelerometeroutputs a voltage change The system has both mechanical microstructures and

electrical signal process units

Accelerometers can measure 1,2 or 3 axis The Analog Devices ADLX203 Accelerometer measures 2

axis

Measures both x and y directions (2-axis) with a range

of 1.7g

Limited to only two axis of rotation and translation

It can measure both dynamic acceleration and static

acceleration


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Prior Research Virtual Reality

Sega Dreamcast

Used first motion sensing control in the form of a fishing

rod

Nintendo Wii

The remote makes use of multi-axis linear accelerationinformation provided from the ADXL330, an integrated

MEMS accelerometer


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Prior Research

Use of Inertial Information forVision Active vision systems are being used in robotic

systems for navigation

Inertial sensors coupled with an active vision

system can provide valuable information Use the inertial sensors to find the ground

plane

Once you know the ground plane, you canknow any objects 3D orientation from thatpoint

Use a Virtual Reality Modeling Language(VRML) for describing the 3D world on thecomputer


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Goals and Objectives

Hypothesis The human head and body is always accelerating even as it

stands still. Assuming a direct line of sight is maintained only

strong enough movements of the head and body would change

the focus and person has from an image to another. With the

data collected from the MEMS accelerometer, it is possible to

measure what kinds of accelerations could affect an image a

person is focusing on.


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Goals and Objectives

Conduct a simple experiment using aMEMS accelerometer

See if accelerometers can measure

movements when placed on glasses

Simulate virtual reality eye-set

Use MATLAB to analyze the movements of

the accelerometer and see if a virtual reality

model can be simulated


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Lab Methods Connected MEMS accelerometer to function

generator and oscilloscope

Secured accelerometer to eye glasses X-axis pointed straight out of the individual

Y-axis pointed to the right of the individual

Measured change in voltage in Oscilloscope andExcel Calibration results for voltage to acceleration conversion

1V = 1g

Acceleration normalized based on nominal voltage

Nominal voltage measured by holding accelerometerstationary


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Data Analysis

MATLAB Input data from Excel into MATLAB code

Code converts accelerometer voltage into

engineering acceleration units

Sensitivity, DC offset, etc.

Acceleration data filtration

Kalman Filtering

An efficient recursive filter that estimates the state of a system

based on incomplete and noisy measurements

Minimum threshold filtering

Acceleration data is valid only if threshold is reached

Double filter provides consistent and more accurate data


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Data Analysis

Kalman Filters 1st Order Implementation

Smoothing a noisy sensor input

2 parameters Amount of previous state information,Dampening effect (R), etc.

The graphs below show that with a Kalman filterimplementation, random noise is decreased

R = 0.001 R = 100R = 10


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Data Analysis - No filter


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Data Analysis Kalman Filter


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Data Analysis Double filter


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Data Analysis Double filter


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Data Analysis


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Data Analysis


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Data Analysis


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Simulation

This is when you take a look at the videobelow.

Dont worry, Ill wait.


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Discussion

Virtual Reality Model Translation in the x and y direction

1st person perspective

Forward accelerations translate to forward

motion based on data analysis Roll and pitch of head

Roll and pitch of head translates to roll and pitch

of virtual world respectively

Capable of several viewing angles of virtualworld


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Discussion

Feasibility

Easily implemented with a wireless connection for

gameplay or other applications

Cheap and robust

Drawbacks

Differentiation of pitching motion from forward

acceleration

Limited to 2 axes preventing yawing motion


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Conclusion

Virtual reality on a rudimentary level

Benefits Cheap and robust

Easily implemented Can be built with a simple

microcontroller and 2 3-axis accelerometers for

redundancy

Additional improvements may involve integrating

a camera for verifying actions

Documents

Lab4 Sec3 Team4 Presentation Edited for Blog