## Reports.DXL320 History

Hide minor edits - Show changes to output

Changed lines 135-137 from:

http://itp.nyu.edu/~mfm317/imu.jpg

to:

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http://itp.nyu.edu/~mfm317/imu.jpg\\

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http://itp.nyu.edu/~mfm317/imu.jpg\\

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Changed lines 93-94 from:

to:

http://itp.nyu.edu/~mfm317/100_0434.jpg\\

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The ~~code~~\\

[[http://itp.nyu.edu/~mfm317/physcomp/pos_from_acce.pde]]

[[http://itp.nyu.edu/~mfm317/physcomp/pos_from_acce.pde]]

to:

'''The Exercise'''\\

Added lines 81-107:

I use a ADXL330 triaxial accelerometer, manufactured by Analog Devices.\\

[[http://www.analog.com/en/prod/0,2877,ADXL330,00.html]]

Range: ±3g\\

Size: 4mm x 4mm x 1.5mm\\

Supply Current: 0.2mA \\

Max BW: 1.6 kHz (X,Y)\\

0.5 kHz (Z)\\

Noise: 2mg (@50Hz) (X,Y)\\

2.5mg (@50Hz) (Z)\\

Cost: $6\\

\\

I use a low Pass Filter and a simple average for the signal to get the acceleration \\

values from the sensor to Processing, My main goal was to be able to use this values \\

with the nature of code (noc) library in order to use the functions of vector math. \\

The exercise didn’t work.\\

The code: [[http://itp.nyu.edu/~mfm317/phycomp/pos_from_acce.pde]]\\

Errors:\\

Bias drift.Changes over time in the baseline (zero input) output.\\

Scale factor drift. Changes over time in the slope of the input-output curve.\\

Drift results in an additive noise, which causes an exponential error. \\

\\

[[http://www.analog.com/en/prod/0,2877,ADXL330,00.html]]

Range: ±3g\\

Size: 4mm x 4mm x 1.5mm\\

Supply Current: 0.2mA \\

Max BW: 1.6 kHz (X,Y)\\

0.5 kHz (Z)\\

Noise: 2mg (@50Hz) (X,Y)\\

2.5mg (@50Hz) (Z)\\

Cost: $6\\

\\

I use a low Pass Filter and a simple average for the signal to get the acceleration \\

values from the sensor to Processing, My main goal was to be able to use this values \\

with the nature of code (noc) library in order to use the functions of vector math. \\

The exercise didn’t work.\\

The code: [[http://itp.nyu.edu/~mfm317/phycomp/pos_from_acce.pde]]\\

Errors:\\

Bias drift.Changes over time in the baseline (zero input) output.\\

Scale factor drift. Changes over time in the slope of the input-output curve.\\

Drift results in an additive noise, which causes an exponential error. \\

\\

Added lines 109-129:

The angular velocity output of a gyroscope can be integrated to determine orientation; \\

so three orthogonal gyroscopes can be used to sense the orientation of a triaxial accelerometer.\\

\\

Alternatively, and to correct integration errors, it is possible to obtain an absolute measure \\

of orientation using the earth's magnetic field, as in a compass, which uses the horizontal \\

components for heading determination.\\

The earth's magnetic field also has a vertical component, and a 3 axis magnetometer can therefore \\

sense two-dimensional (2D) orientation, since it is not possible to sense rotations about the axis \\

of the earth's magnetic field. A combination of accelerometers and magnetometers will give absolute \\

three-dimensional (3D) orientation, except at the magnetic North and South pole (where gravity and \\

earth magnetic field are parallel).\\

IMUs made from low-cost parts quickly diverge from reality because of both poor drift and random walk noise\\

The only solution is to use external information to reset the orientation or position at regular intervals.\\

\\

Several companies have developed inertial sensors combining all three technologies, which give orientation in \\

a global coordinate system (relative to the earth's magnetic and gravitational fields).\\

\\

Changed lines 36-38 from:

integrating, over time, the signals of the sensor as well as any signal errors.

to:

The process of determining velocity and position by integration from acceleration\\

is more problematic than the reverse.

In theory knowing the forces applied to an object it is possible to integrate to \\

find its velocity and position over time.// Positions are found by integrating, over \\

time, the signals of the sensor as well as any signal errors.\\

is more problematic than the reverse.

In theory knowing the forces applied to an object it is possible to integrate to \\

find its velocity and position over time.// Positions are found by integrating, over \\

time, the signals of the sensor as well as any signal errors.\\

Changed lines 59-63 from:

Gravity complicates things – rotation measurements must

compensate for the change in the gravitational vector, which needs to be subtracted from the acceleration.

to:

There are lots of ways to integrate (Polynomial, Simpson’s Rule, etc.)\\

Euler integration is the most basic of numerical integration techniques. It is only \\

completely accurate if the rate of change is constant over the timestep. One possible \\

solution to this problem is to decrease the timestep, but no matter how much it's reduced, \\

the error will keep increasing over time. Errors rapidly accumulate during the integration \\

process and additional knowledge in the form of initial conditions is required for \\

determination of integration constants.\\

Euler integration is the most basic of numerical integration techniques. It is only \\

completely accurate if the rate of change is constant over the timestep. One possible \\

solution to this problem is to decrease the timestep, but no matter how much it's reduced, \\

the error will keep increasing over time. Errors rapidly accumulate during the integration \\

process and additional knowledge in the form of initial conditions is required for \\

determination of integration constants.\\

Added lines 67-68:

Gravity complicates things – rotation measurements must compensate for the change in the \\

gravitational vector, which needs to be subtracted from the acceleration.\\

gravitational vector, which needs to be subtracted from the acceleration.\\

Added lines 70-78:

In the integration process, changes in accelerometer orientation must be accounted for since\\

accelerometer measures acceleration relative to its orientation rather than to the earth or \\

global coordinate system. This underlies the application of accelerometers as inclinometers, \\

where they determine the component of gravity that acts orthogonal to the level.\\

\\

\\

\\

Changed lines 64-65 from:

[[http://itp.nyu.edu~~~mfm317~~/~~phycomp~~/pos_from_acce.pde]]

to:

[[http://itp.nyu.edu/~mfm317/physcomp/pos_from_acce.pde]]

Changed line 8 from:

The idea is take advantage of the unobtrusive nature of the accelerometer to avoid externally referenced motion\\~~ ~~

to:

The idea is take advantage of the unobtrusive nature of the accelerometer to avoid externally referenced motion \\

Changed lines 64-65 from:

to:

[[http://itp.nyu.edu~mfm317/phycomp/pos_from_acce.pde]]

Changed line 7 from:

the Design of propioceptive devices that have sense of its own motion and position.~~\\~~ \\

to:

the Design of propioceptive devices that have sense of its own motion and position. \\

Changed line 7 from:

the Design of propioceptive devices that have sense of its own motion and position.\\

to:

the Design of propioceptive devices that have sense of its own motion and position.\\ \\

Changed lines 6-8 from:

The goal of this report is evaluate the possibility of tracking position from a 3 axis accelerometer to be use in~~ ~~\\

the Design of propioceptive devices that have sense of its own motion and position.~~ ~~\\

The idea is take advantage of the unobtrusive nature of the accelerometer to avoid externally referenced motion~~ ~~\\

the Design of propioceptive devices that have sense of its own motion and position.

The idea is take advantage of the unobtrusive nature of the accelerometer to avoid externally referenced motion

to:

The goal of this report is evaluate the possibility of tracking position from a 3 axis accelerometer to be use in\\

the Design of propioceptive devices that have sense of its own motion and position.\\

The idea is take advantage of the unobtrusive nature of the accelerometer to avoid externally referenced motion\\

the Design of propioceptive devices that have sense of its own motion and position.\\

The idea is take advantage of the unobtrusive nature of the accelerometer to avoid externally referenced motion\\

Changed line 10 from:

The accelerometer is one of the most widely used sensors for capturing context because it is small, inexpensive,~~ ~~\\

to:

The accelerometer is one of the most widely used sensors for capturing context because it is small, inexpensive,\\

Changed line 7 from:

the Design of propioceptive devices that have sense of its own motion and position.\\

to:

the Design of propioceptive devices that have sense of its own motion and position. \\

Changed line 7 from:

the Design of propioceptive devices that have sense of its own motion and position.~~ ~~\\

to:

the Design of propioceptive devices that have sense of its own motion and position.\\

Changed line 7 from:

the Design of propioceptive devices that have sense of its own motion and position.\\

to:

the Design of propioceptive devices that have sense of its own motion and position. \\

Changed line 11 from:

lightweight, and self-operable.\\

to:

lightweight, and self-operable. \\

Changed line 13 from:

use of multiple accelerometers attached to the human body.

to:

use of multiple accelerometers attached to the human body. \\

Changed lines 6-12 from:

The goal of this report is evaluate the possibility of tracking position from a 3 axis accelerometer to be use in the Design of ~~\\~~

propioceptive devices that have sense of its own motion and position.\\

The idea is take advantage of the unobtrusive nature of the accelerometer~~\\~~

to avoid externally referenced motion~~sensing~~ technologies as infrared, ~~\\~~

radar and video that can present interferences.\\

The accelerometer is one of the most widely used sensors for capturing~~\\~~

context because it is small, inexpensive, \\

propioceptive devices that have sense of its own motion and position.\\

The idea is take advantage of the unobtrusive nature of the accelerometer

to avoid externally referenced motion

radar and video that can present interferences.\\

The accelerometer is one of the most widely used sensors for capturing

context because it is small, inexpensive, \\

to:

The goal of this report is evaluate the possibility of tracking position from a 3 axis accelerometer to be use in \\

the Design of propioceptive devices that have sense of its own motion and position.\\

The idea is take advantage of the unobtrusive nature of the accelerometer to avoid externally referenced motion \\

sensing technologies as infrared, radar and video that can present interferences.\\

The accelerometer is one of the most widely used sensors for capturing context because it is small, inexpensive, \\

the Design of propioceptive devices that have sense of its own motion and position.\\

The idea is take advantage of the unobtrusive nature of the accelerometer to avoid externally referenced motion \\

sensing technologies as infrared, radar and video that can present interferences.\\

The accelerometer is one of the most widely used sensors for capturing context because it is small, inexpensive, \\

Changed line 12 from:

In efforts to obtain behavioral patterns, many studies* have reported the\\

to:

In efforts to obtain behavioral patterns, many studies* have reported the \\

Changed lines 6-7 from:

The goal of this report is evaluate the possibility of tracking ~~\\~~

position from a 3 axis accelerometer to be use in the Design of \\

position from a 3 axis accelerometer to be use in the Design of \\

to:

The goal of this report is evaluate the possibility of tracking position from a 3 axis accelerometer to be use in the Design of \\

Changed lines 6-13 from:

The goal of this report is evaluate the possibility of tracking position from a 3 axis accelerometer to be use in~~\\ ~~

the Design of propioceptive devices that have sense of its own motion and position.

The idea is take advantage of the unobtrusive nature of the accelerometer to avoid externally referenced motion

sensing technologies as infrared, radar and video that can present interferences.\\

The accelerometer is one of the most widely used sensors for capturing context because it is small, inexpensive, \\

lightweight, and self-operable.

In efforts to obtain behavioral patterns, many studies* have reported the use of multiple accelerometers attached~~\\~~

to the human body.

the Design of propioceptive devices that have sense of its own motion and position.

The idea is take advantage of the unobtrusive nature of the accelerometer to avoid externally referenced motion

sensing technologies as infrared, radar and video that can present interferences.\\

The accelerometer is one of the most widely used sensors for capturing context because it is small, inexpensive, \\

lightweight, and self-operable.

In efforts to obtain behavioral patterns, many studies* have reported the use of multiple accelerometers attached

to the human body.

to:

The goal of this report is evaluate the possibility of tracking \\

position from a 3 axis accelerometer to be use in the Design of \\

propioceptive devices that have sense of its own motion and position.\\

The idea is take advantage of the unobtrusive nature of the accelerometer \\

to avoid externally referenced motion sensing technologies as infrared, \\

radar and video that can present interferences.\\

The accelerometer is one of the most widely used sensors for capturing \\

context because it is small, inexpensive, \\

lightweight, and self-operable.\\

In efforts to obtain behavioral patterns, many studies* have reported the\\

use of multiple accelerometers attached to the human body.

position from a 3 axis accelerometer to be use in the Design of \\

propioceptive devices that have sense of its own motion and position.\\

The idea is take advantage of the unobtrusive nature of the accelerometer \\

to avoid externally referenced motion sensing technologies as infrared, \\

radar and video that can present interferences.\\

The accelerometer is one of the most widely used sensors for capturing \\

context because it is small, inexpensive, \\

lightweight, and self-operable.\\

In efforts to obtain behavioral patterns, many studies* have reported the\\

use of multiple accelerometers attached to the human body.

Changed lines 25-26 from:

Inertial systems like accelerometers are not well-suited for absolute position tracking and in spite of that in ~~\\~~

theory it’s possible, relative~~ ~~position is difficult to implement in real-life situations.\\

theory it’s possible, relative

to:

Inertial systems like accelerometers are not well-suited for absolute \\

position tracking and in spite of that in theory it’s possible, relative\\

position is difficult to implement in real-life situations.\\

position tracking and in spite of that in theory it’s possible, relative\\

position is difficult to implement in real-life situations.\\

Changed lines 29-33 from:

An accelerometer output is a variable voltage depending on the amount of acceleration applied. The common reference~~\\~~

is the resultant acceleration produce by earth’s gravity force. The unit used for the acceleration measure ~~is ~~g, the ~~\\~~

earth’s gravity at sea level. (1g = 9.8 m/s~2)~~\\~~

Their outputs need to be integrated once with respect to time to get velocity and integrated twice to get position.\\

is

earth’s gravity at sea level. (1g = 9.8 m/s~2)

Their outputs need to be integrated once with respect to time to get velocity and integrated twice to get position.

to:

An accelerometer output is a variable voltage depending on the amount of\\

acceleration applied. The common reference is the resultant acceleration \\

produce by earth’s gravity force. The unit used for the acceleration measure\\

is g, the earth’s gravity at sea level. (1g = 9.8 m/s~2)\\

acceleration applied. The common reference is the resultant acceleration \\

produce by earth’s gravity force. The unit used for the acceleration measure\\

is g, the earth’s gravity at sea level. (1g = 9.8 m/s~2)\\

Changed lines 34-35 from:

to:

Their outputs need to be integrated once with respect to time to get velocity \\

and integrated twice to get position.\\

and integrated twice to get position.\\

Changed lines 37-38 from:

position over time.// Positions are found by integrating, over time, the signals of the sensor as well as any signal errors.

to:

Force = Mass * Acceleration\\ '''Acceleration = Force / Mass\\

Changed lines 39-43 from:

One of the first problems is

the greater the delay. In Addition, acceleration is the second derivative.\\

The second consideration is

This amplifies high-frequency noise, which can swamp out the signal

to:

In theory, if we knowing the the forces applied to an object it is possible to\\

integrate to find its velocity and position over time.// Positions are found by\\

integrating, over time, the signals of the sensor as well as any signal errors.\\

integrate to find its velocity and position over time.// Positions are found by\\

integrating, over time, the signals of the sensor as well as any signal errors.\\

Changed lines 44-49 from:

to:

One of the first problems is the time lag. The more accurate your derivative \\

(ie, the more points back in time you look), the greater the delay. In Addition,\\

acceleration is the second derivative.\\

The second consideration is the Frecuency Noise. A pure differentiator provides \\

a linearly increasing gain with frequency.

This amplifies high-frequency noise, which can swamp out the signal.\\

(ie, the more points back in time you look), the greater the delay. In Addition,\\

acceleration is the second derivative.\\

The second consideration is the Frecuency Noise. A pure differentiator provides \\

a linearly increasing gain with frequency.

This amplifies high-frequency noise, which can swamp out the signal.\\

Added lines 54-56:

\\

Changed lines 22-35 from:

Inertial systems ~~are not~~ well-suited for absolute position tracking and in spite of that in theory it’s possible relative position ~~ ~~is difficult

to implement in real-life situations\\

An accelerometer output is a variable voltage depending on the amount of acceleration applied. The common reference is the resultant acceleration produce by earth’s gravity force. The unit used for the acceleration measure is g, the earth’s gravity at sea level. (1g = 9.8 m/s~2)

Their outputs need to be integrated once with respect to time to get velocity and integrated twice to get position.//

Force = Mass * Acceleration //

'''Acceleration = Force / Mass //

In theory , if we know the the forces applied to an object we can integrate to find its velocity and position over time.//

Positions are found by integrating, over time, the signals of the sensor as well as any signal errors\\

to implement in real-life situations\\

An accelerometer output is a variable voltage depending on the amount of acceleration applied. The common reference is the resultant acceleration produce by earth’s gravity force. The unit used for the acceleration measure is g, the earth’s gravity at sea level. (1g = 9.8 m/s~2)

Their outputs need to be integrated once with respect to time to get velocity and integrated twice to get position.//

Force = Mass * Acceleration //

'''Acceleration = Force / Mass //

In theory , if we know the the forces applied to an object we can integrate to find its velocity and position over time.//

Positions are found by integrating, over time, the signals of the sensor as well as any signal errors\\

to:

Inertial systems like accelerometers are not well-suited for absolute position tracking and in spite of that in \\

theory it’s possible, relative position is difficult to implement in real-life situations.\\

theory it’s possible, relative position is difficult to implement in real-life situations.\\

Changed lines 25-30 from:

the greater the delay

The second consideration is

to:

An accelerometer output is a variable voltage depending on the amount of acceleration applied. The common reference\\

is the resultant acceleration produce by earth’s gravity force. The unit used for the acceleration measure is g, the \\

earth’s gravity at sea level. (1g = 9.8 m/s~2)\\

Their outputs need to be integrated once with respect to time to get velocity and integrated twice to get position.\\

is the resultant acceleration produce by earth’s gravity force. The unit used for the acceleration measure is g, the \\

earth’s gravity at sea level. (1g = 9.8 m/s~2)\\

Their outputs need to be integrated once with respect to time to get velocity and integrated twice to get position.\\

Changed lines 31-32 from:

to:

Force = Mass * Acceleration \\ '''Acceleration = Force / Mass \\

Changed lines 33-39 from:

Euler integration is the most basic of numerical integration techniques.It is only completly accurate if the rate of change is constant over the timestep.One possible solution to this problem is to decrease

Gravity complicates things – rotation measurements must

compensate for the change in the gravitational vector, which needs to be subtracted from the acceleration

to:

In theory, if we knowing the the forces applied to an object it is possible to integrate to find its velocity and \\

position over time.// Positions are found by integrating, over time, the signals of the sensor as well as any signal errors.\\

position over time.// Positions are found by integrating, over time, the signals of the sensor as well as any signal errors.\\

Added lines 36-40:

One of the first problems is the time lag. The more accurate your derivative (ie, the more points back in time you look),\\

the greater the delay. In Addition, acceleration is the second derivative.\\

The second consideration is the Frecuency Noise. A pure differentiator provides a linearly increasing gain with frequency.

This amplifies high-frequency noise, which can swamp out the signal.\\

Changed lines 42-44 from:

to:

Added lines 45-60:

\\

'''Numerical Integration'''\\

Euler integration is the most basic of numerical integration techniques.It is only completly accurate if the rate of change is constant over the timestep.One possible solution to this problem is to decrease the timestep, but no matter how much it's reduced, the error will keep increasing over time. \\

Gravity complicates things – rotation measurements must

compensate for the change in the gravitational vector, which needs to be subtracted from the acceleration.\\

\\

\\

The code\\

\\

Changed lines 5-9 from:

Not externally referenced motion sensing technologies as infrared, radar and video.(oclusion and interferences)\\

The accelerometer is one of the most widely used sensors for capturing context because it is small, inexpensive, lightweight, and self-operable.\\

In efforts to obtain behavioral patterns, many studies* have reported the use of multiple accelerometers attached to the human body.

to:

The goal of this report is evaluate the possibility of tracking position from a 3 axis accelerometer to be use in\\

the Design of propioceptive devices that have sense of its own motion and position.

The idea is take advantage of the unobtrusive nature of the accelerometer to avoid externally referenced motion

sensing technologies as infrared, radar and video that can present interferences.\\

The accelerometer is one of the most widely used sensors for capturing context because it is small, inexpensive, \\

lightweight, and self-operable.

In efforts to obtain behavioral patterns, many studies* have reported the use of multiple accelerometers attached \\

to the human body.

Added line 15:

Deleted lines 16-17:

http://itp.nyu.edu/~mfm317/table.jpg

Added lines 18-20:

http://itp.nyu.edu/~mfm317/table.jpg

\\

Changed lines 38-41 from:

compensate for the change in the gravitational vector, which needs to be subtracted from the acceleration.\\

to:

Added lines 46-51:

Gravity complicates things – rotation measurements must

compensate for the change in the gravitational vector, which needs to be subtracted from the acceleration.\\

The code\\

compensate for the change in the gravitational vector, which needs to be subtracted from the acceleration.\\

The code\\

Changed line 4 from:

Why? \\

to:

'''Why?''' \\

Changed line 15 from:

The problem \\

to:

'''The problem''' \\

Changed lines 24-25 from:

Acceleration = Force / Mass //

to:

'''Acceleration = Force / Mass //

Changed lines 43-44 from:

Numerical Integration\\

to:

'''Numerical Integration'''\\

Changed line 49 from:

Options~~:~~\\

to:

'''Options'''\\

Changed lines 45-47 from:

Euler integration is the most basic of numerical integration techniques.It is only completly accurate if the rate of change is constant over the timestep.

to:

Euler integration is the most basic of numerical integration techniques.It is only completly accurate if the rate of change is constant over the timestep.One possible solution to this problem is to decrease the timestep, but no matter how much it's reduced, the error will keep increasing over time. \\

Deleted lines 48-50:

\\

Changed line 61 from:

Crossbow [[http://www.xbow.com]]~~ ~~\\~~ ~~

to:

Crossbow [[http://www.xbow.com]]\\

Changed line 45 from:

Euler integration is the most basic of numerical integration techniques.It is only completly accurate if the rate of change is constant over the ~~timestep~~

to:

Euler integration is the most basic of numerical integration techniques.It is only completly accurate if the rate of change is constant over the timestep.

Added lines 44-45:

Euler integration is the most basic of numerical integration techniques.It is only completly accurate if the rate of change is constant over the timestep

Changed lines 32-33 from:

to:

the greater the delay. In Addition, acceleration is the second derivative\\

Deleted lines 26-33:

\\

Added lines 28-29:

Changed lines 31-40 from:

The more accurate your derivative (ie,

Acceleration is the second derivative\\

'''\\

Frequency noise\\

A pure differentiator provides a linearly increasing gain with frequency. This amplifies high-frequency noise which can swamp out the signal.

Often have to low-pass before and/or after

to:

One of the first problems is the time lag. The more accurate your derivative (ie, the more points back in time you look),//

the greater the delay. In Addition, acceleration is the second derivative\\

The second consideration is the Frecuency Noise. A pure differentiator provides a linearly increasing gain with frequency. This amplifies high-frequency noise which can swamp out the signal.\\

the greater the delay. In Addition, acceleration is the second derivative\\

The second consideration is the Frecuency Noise. A pure differentiator provides a linearly increasing gain with frequency. This amplifies high-frequency noise which can swamp out the signal.\\

Added lines 38-42:

Gravity complicates things – rotation measurements must

compensate for the change in the gravitational vector, which needs to be subtracted from the acceleration.\\

\\

compensate for the change in the gravitational vector, which needs to be subtracted from the acceleration.\\

\\

Changed line 46 from:

to:

Deleted lines 47-50:

compensate for the change in the gravitational vector, which needs to besubtracted from the acceleration.\\

\\

Added lines 18-33:

An accelerometer output is a variable voltage depending on the amount of acceleration applied. The common reference is the resultant acceleration produce by earth’s gravity force. The unit used for the acceleration measure is g, the earth’s gravity at sea level. (1g = 9.8 m/s~2)

Their outputs need to be integrated once with respect to time to get velocity and integrated twice to get position.//

Force = Mass * Acceleration //

Acceleration = Force / Mass //

In theory , if we know the the forces applied to an object we can integrate to find its velocity and position over time.//

Changed lines 24-25 from:

\\

to:

'''\\

Changed lines 56-67 from:

to:

'''*Reference papers'''\\

'''Activity Recognition from Accelerometer Data'''\\

Nishkam Ravi, Nikhil Dandekar, Preetham Mysore and Michael L. Littman.\\

'''Activity Recognition from User-Annotated from Accelerometer Data'''\\

L. Bao and S. Intille\\

'''A Method for deriving displacement data during cyclical movement using an inertial sensor'''\\

'''Activity Recognition from Accelerometer Data'''\\

Nishkam Ravi, Nikhil Dandekar, Preetham Mysore and Michael L. Littman.\\

'''Activity Recognition from User-Annotated from Accelerometer Data'''\\

L. Bao and S. Intille\\

'''A Method for deriving displacement data during cyclical movement using an inertial sensor'''\\

Changed line 52 from:

Crossbow [[http://www.xbow.com]]\\

to:

Crossbow [[http://www.xbow.com]] \\

Changed lines 48-56 from:

Xsens Motion Technologies [[http://www.xsens.com]]

MicroStrain [[http://www.microstrain.com]]

Cloud Cap Technology [[http://www.cloudcaptech.com]]

Intersense [[http://www.isense.com]]

Crossbow [[http://www.xbow.com]]

MIT: [[http://www.media.mit.edu/resenv/Stack]]

MicroStrain [[http://www.microstrain.com]]

Cloud Cap Technology [[http://www.cloudcaptech.com]]

Intersense [[http://www.isense.com]]

Crossbow [[http://www.xbow.com]]

MIT: [[http://www.media.mit.edu/resenv/Stack]]

to:

Xsens Motion Technologies [[http://www.xsens.com]]\\

MicroStrain [[http://www.microstrain.com]]\\

Cloud Cap Technology [[http://www.cloudcaptech.com]]\\

Intersense [[http://www.isense.com]]\\

Crossbow [[http://www.xbow.com]]\\

MIT: [[http://www.media.mit.edu/resenv/Stack]]\\

MicroStrain [[http://www.microstrain.com]]\\

Cloud Cap Technology [[http://www.cloudcaptech.com]]\\

Intersense [[http://www.isense.com]]\\

Crossbow [[http://www.xbow.com]]\\

MIT: [[http://www.media.mit.edu/resenv/Stack]]\\

Changed lines 41-56 from:

to:

Options:\\

Inertial Measurement Units\\

An inertial measurement unit (IMU) is a sensor package containing three orthogonal axes of rate sensors (gyros) and three orthogonal axes of acceleration sensors (accelerometers)\\

Often supplemented with additional sensors for calibration (i.e., magnetometers provide a rudimentary degree of orientation reference)\\

Historically used for inertial navigation or tracking \\

Typically on the order of $1000\\

Xsens Motion Technologies [[http://www.xsens.com]]

MicroStrain [[http://www.microstrain.com]]

Cloud Cap Technology [[http://www.cloudcaptech.com]]

Intersense [[http://www.isense.com]]

Crossbow [[http://www.xbow.com]]

MIT: [[http://www.media.mit.edu/resenv/Stack]]

Inertial Measurement Units\\

An inertial measurement unit (IMU) is a sensor package containing three orthogonal axes of rate sensors (gyros) and three orthogonal axes of acceleration sensors (accelerometers)\\

Often supplemented with additional sensors for calibration (i.e., magnetometers provide a rudimentary degree of orientation reference)\\

Historically used for inertial navigation or tracking \\

Typically on the order of $1000\\

Xsens Motion Technologies [[http://www.xsens.com]]

MicroStrain [[http://www.microstrain.com]]

Cloud Cap Technology [[http://www.cloudcaptech.com]]

Intersense [[http://www.isense.com]]

Crossbow [[http://www.xbow.com]]

MIT: [[http://www.media.mit.edu/resenv/Stack]]

Changed lines 28-41 from:

Often have to low-pass before and/or after high-passing.

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Often have to low-pass before and/or after high-passing.\\

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Numerical Integration\\

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Acceleration is the rate of change in velocity over time. If we can integrate (sum) these changes in velocity over time we can keep track of the velocity at each point in time. Knowing the velocity at any time is it possible to use it to update position over time. This is because velocity is the rate of change of position over time just as acceleration is the rate of change of velocity.\\

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Gravity complicates things – rotation measurements must

compensate for the change in the gravitational vector, which needs to besubtracted from the acceleration.\\

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Numerical Integration\\

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Acceleration is the rate of change in velocity over time. If we can integrate (sum) these changes in velocity over time we can keep track of the velocity at each point in time. Knowing the velocity at any time is it possible to use it to update position over time. This is because velocity is the rate of change of position over time just as acceleration is the rate of change of velocity.\\

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Gravity complicates things – rotation measurements must

compensate for the change in the gravitational vector, which needs to besubtracted from the acceleration.\\

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Often have to low-pass before and/or after high-passing~~ (see above)~~.

to:

Often have to low-pass before and/or after high-passing.

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Why?

~~Design~~ of propioceptive devices that ha a sense of its own motion and position. Unobtrusive.

Not externally referenced motion sensing technologies as infrared, radar and video.(oclusion and interferences)

The accelerometer is one of the most widely used sensors for capturing context because it is small, inexpensive, lightweight, and self-operable.~~In ~~efforts to obtain behavioral patterns, many studies* have reported the use of multiple accelerometers attached to the human body.

Not externally referenced motion sensing technologies as infrared, radar and video.(oclusion and interferences)

The accelerometer is one of the most widely used sensors for capturing context because it is small, inexpensive, lightweight, and self-operable.

to:

Why? \\

Design of propioceptive devices that ha a sense of its own motion and position. Unobtrusive.\\

Not externally referenced motion sensing technologies as infrared, radar and video.(oclusion and interferences)\\

The accelerometer is one of the most widely used sensors for capturing context because it is small, inexpensive, lightweight, and self-operable.\\

In efforts to obtain behavioral patterns, many studies* have reported the use of multiple accelerometers attached to the human body.\\

\\

\\

Design of propioceptive devices that ha a sense of its own motion and position. Unobtrusive.\\

Not externally referenced motion sensing technologies as infrared, radar and video.(oclusion and interferences)\\

The accelerometer is one of the most widely used sensors for capturing context because it is small, inexpensive, lightweight, and self-operable.\\

In efforts to obtain behavioral patterns, many studies* have reported the use of multiple accelerometers attached to the human body.\\

\\

\\

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The problem

~~Inertial~~ systems are not well-suited for absolute position tracking and in spite of that in theory it’s possible relative position is difficult to implement in real-life situations

Positions are found by integrating, over time, the signals of the sensor as well as any signal errors

Time~~lag~~

Positions are found by integrating, over time, the signals of the sensor as well as any signal errors

Time

to:

The problem \\

Inertial systems are not well-suited for absolute position tracking and in spite of that in theory it’s possible relative position is difficult

to implement in real-life situations\\

Positions are found by integrating, over time, the signals of the sensor as well as any signal errors\\

Time lag\\

Inertial systems are not well-suited for absolute position tracking and in spite of that in theory it’s possible relative position is difficult

to implement in real-life situations\\

Positions are found by integrating, over time, the signals of the sensor as well as any signal errors\\

Time lag\\

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Acceleration is the second derivative

Frequency~~noise~~

Frequency

to:

Acceleration is the second derivative\\

\\

Frequency noise\\

\\

Frequency noise\\

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http://itp.nyu.edu/~mfm317/table.~~jpg~~

to:

http://itp.nyu.edu/~mfm317/table.jpg

The problem

Inertial systems are not well-suited for absolute position tracking and in spite of that in theory it’s possible relative position is difficult to implement in real-life situations

Positions are found by integrating, over time, the signals of the sensor as well as any signal errors

Time lag

The more accurate your derivative (ie, the more points back in time you look), the greater the delay.

Acceleration is the second derivative

Frequency noise

A pure differentiator provides a linearly increasing gain with frequency. This amplifies high-frequency noise which can swamp out the signal.

Often have to low-pass before and/or after high-passing (see above).

The problem

Inertial systems are not well-suited for absolute position tracking and in spite of that in theory it’s possible relative position is difficult to implement in real-life situations

Positions are found by integrating, over time, the signals of the sensor as well as any signal errors

Time lag

The more accurate your derivative (ie, the more points back in time you look), the greater the delay.

Acceleration is the second derivative

Frequency noise

A pure differentiator provides a linearly increasing gain with frequency. This amplifies high-frequency noise which can swamp out the signal.

Often have to low-pass before and/or after high-passing (see above).

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Context awareness

Data collection and data interpretation

to:

http://itp.nyu.edu/~mfm317/table.jpg

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Getting position data from a 3 axis accelerometer

to:

!!Getting position data from a 3 axis accelerometer

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Getting position data from a 3 axis accelerometer

Why?

Design of propioceptive devices that ha a sense of its own motion and position. Unobtrusive.

Not externally referenced motion sensing technologies as infrared, radar and video.(oclusion and interferences)

The accelerometer is one of the most widely used sensors for capturing context because it is small, inexpensive, lightweight, and self-operable. In efforts to obtain behavioral patterns, many studies* have reported the use of multiple accelerometers attached to the human body.

The relation with Activity and Motion recognition

Context awareness. Ubiquitous computing

Data collection and data interpretation

Why?

Design of propioceptive devices that ha a sense of its own motion and position. Unobtrusive.

Not externally referenced motion sensing technologies as infrared, radar and video.(oclusion and interferences)

The accelerometer is one of the most widely used sensors for capturing context because it is small, inexpensive, lightweight, and self-operable. In efforts to obtain behavioral patterns, many studies* have reported the use of multiple accelerometers attached to the human body.

The relation with Activity and Motion recognition

Context awareness. Ubiquitous computing

Data collection and data interpretation