AccelerometersAccelerometers

Richard ManningRichard Manning

Accelerometers in GeneralAccelerometers in General

In general, an accelerometer is a device that is used to measure its own acceleration In general, an accelerometer is a device that is used to measure its own acceleration

in comparison to a reference based on remote sensing.in comparison to a reference based on remote sensing.

What Accelerometers are Ripping OffWhat Accelerometers are Ripping Off

The accelerometer is essentially a mechanical duplicate for the balance organs The accelerometer is essentially a mechanical duplicate for the balance organs

inherent in many organic species.inherent in many organic species.

Examples include:Examples include:

-Human inner ear-Human inner ear

-Aquatic invertebrate statocysts-Aquatic invertebrate statocysts

Common Types of AccelerometersCommon Types of Accelerometers

-Strain Gauge

-Surface Micromachined Capacitive

-Electromechanical Servo

-Magnetic Induction

-Thermal (through submicron CMOS process)

-Resonance

This is a micromachined accelerometer

Other Types AccelerometersOther Types Accelerometers

-Laser Accelerometer

-Surface Acoustic Wave

-Optical

-Piezo-film or piezoelectric sensor

-Bulk Micromachined Capactive

Styles of AccelerometersStyles of Accelerometers

Accelerometers are available in many different styles of packaging and output. Accelerometers are available in many different styles of packaging and output.

Common types are:Common types are:

-Ratiometric Analog-Ratiometric Analog

-Sensing Mv/g-Sensing Mv/g

-Absolute Analog-Absolute Analog

-Sensing Mv/g-Sensing Mv/g

-PWM-PWM

-Sensing % duty cycle/g-Sensing % duty cycle/g

Common Uses for AccelerometersCommon Uses for Accelerometers

An accelerometer designed by the Archimedes Automated Assembly Planning Project at Sandia National Laboratory

One of the most common places that accelerometers are found is in the automotive industry. They are used to determine when collisions occur and when to trigger the air bags.

This is a graph of automotive accelerometers and shows the difference between normal automobile operation and a collision. A single accelerometer can replace between 3 to 5 g switches.

Accelerometers Where you Would not ThinkAccelerometers Where you Would not Think

Nintendo has confirmed that the upcoming Wii pointer makes use of accelerometers to drive its tilt and pointing capacity. Also, the nunchaku controller add on also has accelerometers built in to enhance gameplay.

Accelerometer DrawbacksAccelerometer Drawbacks

-Accelerometers can get expensive when needed to operate in high temperatures

-Accelerometers can have some difficulty working with tilt signals when acceleration is occurring

-Accelerometers can generate noise that can hurt their signal resolution

-Accelerometers can not tell the difference between tilt and motion, but no sensor currently can either

Things to Remember for Choosing Things to Remember for Choosing AccelerometersAccelerometers

-Determine the temperature range at which the sensor must operate

-Determine the power demands of the sensor

-Determine the voltage output when the sensor is at its neutral position

-Decide what sensitivity you need

-Decide how much variance in sensitivity is acceptable if rapid temperature shifts are to be expected

-Acceleration is a vector that the accelerometer measures along its sensitive axes

Accelerometers in RecapAccelerometers in Recap

-Accelerometers are devices that are used to measure their movement in comparison -Accelerometers are devices that are used to measure their movement in comparison

to a reference based on remote sensing.to a reference based on remote sensing.

-They are many different types of accelerometers-They are many different types of accelerometers

-Accelerometers are used in many places, including the automotive industry and in -Accelerometers are used in many places, including the automotive industry and in many consumer electronicsmany consumer electronics

-There are several different ways that accelerometers can measure their movement, -There are several different ways that accelerometers can measure their movement, including PWM, Ratiometric analog, and absolute analogincluding PWM, Ratiometric analog, and absolute analog

-They range greatly in cost and in resolution-They range greatly in cost and in resolution

SourcesSources

www.analog.com/Analog_Root/static/library/techArticles/mems/Sensor971/sld5.htmlwww.analog.com/Analog_Root/static/library/techArticles/mems/Sensor971/sld5.html

http://en.wikipedia.org/wiki/Accelerometerhttp://en.wikipedia.org/wiki/Accelerometer

www.societyofrobots.com/sensors_accelerometer.shtmlwww.societyofrobots.com/sensors_accelerometer.shtml

www.memsic.com/memsic/products/search_xlkuang.aspwww.memsic.com/memsic/products/search_xlkuang.asp

www.vernier.com/probes/acc-group.htmlwww.vernier.com/probes/acc-group.html

QuestionsQuestions