Accelerometer for anti-flip
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Posts: 46,084
I have been fascinated to follow and the links to Analog's accelerometer
datasheets. Here is a photo of the
application it calls to mind, a high speed trifoiler:
http://www.speedsailing.com/Boats_Trifoiler.htm
Multihull sailboats have a (notorious) tendency to flip, but the hydrofoil
machines are stabilized mechanically,
using a "sensor" that precedes each pontoon. The sensor is basically a float.
If one pontoon tries to rise
excessively, the sensor notices and, by pushrod, adjusts the angle of attack of
the hyrofoil. This corrects the
tilt.
It is a proved system, but maybe it is also a little draggy, hydrodynamically,
and I have wondered if an electronic
sensor might be quicker on the uptake. Specifically, I wonder if the Analog
Devices accelerometer it could be
applied, using the Stamp, to a small R/C model of a catamaran to test the idea.
Could it work?
These boats are thrilling to race, but sooner or later (sooner) they flip. A
gust hits, and over they go.
The smaller the worser, because catamarans depend on their wide stance for their
basic stability. At the level of
toy boats and r/c models, multis are thought to be impractical at waterline
lengths below about 50 inches .
What I have in mind is a much smaller species of cat. Like 12 inches square.
In your experience, can the Stamp/accelerometer detect and respond to really
sudden changes in tilt?
Thank you for your insights.
Michael
datasheets. Here is a photo of the
application it calls to mind, a high speed trifoiler:
http://www.speedsailing.com/Boats_Trifoiler.htm
Multihull sailboats have a (notorious) tendency to flip, but the hydrofoil
machines are stabilized mechanically,
using a "sensor" that precedes each pontoon. The sensor is basically a float.
If one pontoon tries to rise
excessively, the sensor notices and, by pushrod, adjusts the angle of attack of
the hyrofoil. This corrects the
tilt.
It is a proved system, but maybe it is also a little draggy, hydrodynamically,
and I have wondered if an electronic
sensor might be quicker on the uptake. Specifically, I wonder if the Analog
Devices accelerometer it could be
applied, using the Stamp, to a small R/C model of a catamaran to test the idea.
Could it work?
These boats are thrilling to race, but sooner or later (sooner) they flip. A
gust hits, and over they go.
The smaller the worser, because catamarans depend on their wide stance for their
basic stability. At the level of
toy boats and r/c models, multis are thought to be impractical at waterline
lengths below about 50 inches .
What I have in mind is a much smaller species of cat. Like 12 inches square.
In your experience, can the Stamp/accelerometer detect and respond to really
sudden changes in tilt?
Thank you for your insights.
Michael
Comments
There is a filter capacitor that allows the user to set the response time of the
unit. This allows
the designer to filter out noise/vibration at frequencies above which the system
is looking to
measure. The datasheets for the ADXL202 lay out formulas for finding the
capacitance needed
to achieve the response time desired. You also have control over the frequency
of the modulated
pulse train. Since my particular BS2 application is memory intensive, I set the
frequency such
that the maximum result of the PULSIN command will fit into a byte rather than a
word. You
might use this flexibility to optimize your response time. As for the BS2's
response time, I don't
think that will be the issue at all. I think the issues will be:
1. Differentiating between real tilts vs lateral accelerations.
2. Selecting a response time and algorithm to respond quickly to unwanted tilts
while not
responding to short term effects of waves, etc.
I would approach this problem with a gyro sensor (possibly matched with a BS2),
which is
by design better suited to this application.
Best of luck.
Clark Hughes
Michael Gianturco wrote:
> I have been fascinated to follow and the links to Analog's accelerometer
datasheets. Here is a photo of the
> application it calls to mind, a high speed trifoiler:
>
> http://www.speedsailing.com/Boats_Trifoiler.htm
>
> Multihull sailboats have a (notorious) tendency to flip, but the hydrofoil
machines are stabilized mechanically,
> using a "sensor" that precedes each pontoon. The sensor is basically a float.
If one pontoon tries to rise
> excessively, the sensor notices and, by pushrod, adjusts the angle of attack
of the hyrofoil. This corrects the
> tilt.
>
> It is a proved system, but maybe it is also a little draggy, hydrodynamically,
and I have wondered if an electronic
> sensor might be quicker on the uptake. Specifically, I wonder if the Analog
Devices accelerometer it could be
> applied, using the Stamp, to a small R/C model of a catamaran to test the
idea.
>
> Could it work?
>
> These boats are thrilling to race, but sooner or later (sooner) they flip. A
gust hits, and over they go.
>
> The smaller the worser, because catamarans depend on their wide stance for
their basic stability. At the level of
> toy boats and r/c models, multis are thought to be impractical at waterline
lengths below about 50 inches .
>
> What I have in mind is a much smaller species of cat. Like 12 inches square.
>
> In your experience, can the Stamp/accelerometer detect and respond to really
sudden changes in tilt?
>
> Thank you for your insights.
>
> Michael
>
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