Reports.DXL320 History

Hide minor edits - Show changes to output

May 09, 2007, at 02:19 PM by Maria Mendez -
Changed lines 135-137 from:
http://itp.nyu.edu/~mfm317/imu.jpg
to:
\\
http://itp.nyu.edu/~mfm317/imu.jpg\\
\\
May 09, 2007, at 02:19 PM by Maria Mendez -
Added lines 136-137:
http://itp.nyu.edu/~mfm317/imu.jpg
May 09, 2007, at 02:10 PM by Maria Mendez -
Changed lines 93-94 from:
to:
http://itp.nyu.edu/~mfm317/100_0434.jpg\\
\\
May 09, 2007, at 02:02 PM by Maria Mendez -
Changed lines 79-81 from:
The code\\
[[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. \\


\\
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).\\
\\
May 09, 2007, at 01:56 PM by Maria Mendez -
Changed lines 36-38 from:
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.
\\
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.\\
Changed lines 59-63 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 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.
\\
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
.\\
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.\\
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.\\

\\
\\
\\
May 09, 2007, at 12:48 AM by Maria Mendez -
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]]
May 09, 2007, at 12:45 AM by Maria Mendez -
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]]
May 08, 2007, at 11:47 PM by Maria Mendez -
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. \\
May 08, 2007, at 11:47 PM by Maria Mendez -
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.\\ \\
May 08, 2007, at 11:46 PM by Maria Mendez -
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 \\
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\\
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,\\
May 08, 2007, at 11:42 PM by Maria Mendez -
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. \\
May 08, 2007, at 11:42 PM by Maria Mendez -
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.\\
May 08, 2007, at 11:41 PM by Maria Mendez -
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. \\
May 08, 2007, at 11:41 PM by Maria Mendez -
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, \\
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, \\
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 \\
May 08, 2007, at 11:39 PM by Maria Mendez -
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 \\
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 \\
May 08, 2007, at 11:38 PM by Maria Mendez -
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.
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.
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.\\
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.\\
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.
\\
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)\\
Changed lines 34-35 from:
Force = Mass * Acceleration \\ '''Acceleration = Force / Mass \\
to:
Their outputs need to be integrated once with respect to time to get velocity \\
and integrated twice to get position.
\\
Changed lines 37-38 from:
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.
\\
to:
Force = Mass * Acceleration\\ '''Acceleration = Force / Mass\\
Changed lines 39-43 from:

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
.\\
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.\\
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.\\
Added lines 54-56:


\\
May 08, 2007, at 11:33 PM by Maria Mendez -
May 08, 2007, at 11:33 PM by Maria Mendez -
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:
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.\\
Changed lines 25-30 from:
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.\\
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
.\\
Changed lines 31-32 from:
to:
Force = Mass * Acceleration \\ '''Acceleration = Force / Mass \\
Changed lines 33-39 from:
'''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
.\\
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.\\
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:
The code\\
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\\


\\
May 08, 2007, at 11:29 PM by Maria Mendez -
Changed lines 5-9 from:
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.
\\
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
\\
April 25, 2007, at 06:09 PM by Maria Mendez -
Changed lines 48-49 from:
to:
\\
\\
April 25, 2007, at 06:08 PM by Maria Mendez -
Changed lines 38-41 from:
Gravity complicates things – rotation measurements must
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\\
April 25, 2007, at 06:04 PM by Maria Mendez -
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'''\\
April 25, 2007, at 06:03 PM by Maria Mendez -
Added lines 76-77:
April 25, 2007, at 06:01 PM by Maria Mendez -
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:


\\
April 25, 2007, at 05:59 PM by Maria Mendez -
Changed line 61 from:
Crossbow [[http://www.xbow.com]] \\
to:
Crossbow [[http://www.xbow.com]]\\
April 25, 2007, at 05:58 PM by Maria Mendez -
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.
April 25, 2007, at 05:56 PM by Maria Mendez -
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
April 25, 2007, at 05:54 PM by Maria Mendez -
Changed lines 32-33 from:
the greater the delay. In Addition, acceleration is the second derivative\\
to:
the greater the delay. In Addition, acceleration is the second derivative\\
April 25, 2007, at 05:53 PM by Maria Mendez -
April 25, 2007, at 05:53 PM by Maria Mendez -
Deleted lines 26-33:







\\
Added lines 28-29:
Changed lines 31-40 from:
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.\\
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.\\
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.\\


\\
Changed line 46 from:
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.\\
to:
Deleted lines 47-50:
Gravity complicates things – rotation measurements must
compensate for the change in the gravitational vector, which needs to besubtracted from the acceleration.\\

\\
April 25, 2007, at 05:47 PM by Maria Mendez -
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.//





April 25, 2007, at 05:40 PM by Maria Mendez -
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'''\\


April 11, 2007, at 06:01 PM by Maria Mendez -
Changed line 52 from:
Crossbow [[http://www.xbow.com]]\\
to:
Crossbow [[http://www.xbow.com]] \\
April 11, 2007, at 06:00 PM by Maria Mendez -
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]]
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]]\\
April 11, 2007, at 06:00 PM by Maria Mendez -
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]]

April 11, 2007, at 05:57 PM by Maria Mendez -
Changed lines 28-41 from:
Often have to low-pass before and/or after high-passing.
to:
Often have to low-pass before and/or after high-passing.\\


\\
Numerical Integration\\
\\

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.\\
\\
Gravity complicates things – rotation measurements must
compensate for the change in the gravitational vector, which needs to besubtracted from the acceleration.\\

\\
April 11, 2007, at 05:56 PM by Maria Mendez -
Changed line 14 from:
to:
\\
Changed line 18 from:
to:
\\
Changed line 20 from:
to:
\\
Changed line 28 from:
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.
April 11, 2007, at 05:55 PM by Maria Mendez -
Changed lines 4-10 from:
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.
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.\\

\\
\\
Changed lines 15-20 from:
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
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\\
Changed lines 23-24 from:
Acceleration is the second derivative
Frequency noise
to:
Acceleration is the second derivative\\
\\

Frequency noise\\
April 11, 2007, at 05:53 PM by Maria Mendez -
Changed lines 11-23 from:
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).
April 11, 2007, at 05:52 PM by Maria Mendez -
Changed lines 11-13 from:
The relation with Activity and Motion recognition
Context awareness
. Ubiquitous computing
Data collection and data interpretation
to:
http://itp.nyu.edu/~mfm317/table.jpg
April 11, 2007, at 05:50 PM by Maria Mendez -
Changed lines 1-3 from:
Getting position data from a 3 axis accelerometer
to:
!!Getting position data from a 3 axis accelerometer
April 11, 2007, at 05:49 PM by Maria Mendez -
Added lines 1-13:
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