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• Hi, I was planning make a hand with Servo and Force Sensing Resitors and found some Force Sensor Resistors (Interlink Electronics) with reasonable price.
Nov 20, 2004 1 of 5
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Hi,

I was planning make a hand with Servo and Force Sensing
Resitors and found some Force Sensor Resistors (Interlink
Electronics) with reasonable price.

to make the hand.

http://www.drrobot.com/products_item.asp?itemNumber=FSR400

Thanks!

• Adam, These look like cool little sensors. I may get a pack just to experiment with. I m still trying to get a handle on what you are trying to do. I assume
Nov 22, 2004 1 of 5
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These look like cool little sensors. I may get a pack just to
experiment with.

I'm still trying to get a handle on what you are trying to do. I
assume the FSR's are to be used as fingertip sensors. How are you
planning on connecting the feedback loop between the FSR and the
servo?

The amount of force you want to use to pick up and hold an object
depends on the weight, texture, and delicacy of the object. The
design of the hand can also have a significant effect. By my
calculations the minimum force that these sensors are designed to
detect is over 5/8 of a pound. Does this sound reasonable for your
application?

Terry

>
>
> Hi,
>
> I was planning make a hand with Servo and Force Sensing
> Resitors and found some Force Sensor Resistors (Interlink
> Electronics) with reasonable price.
>
> to make the hand.
>
> http://www.drrobot.com/products_item.asp?itemNumber=FSR400
>
> Thanks!
>
• Terry, I get a bit less as the minimum force sensitivity. As I read the data sheet, the force sensitivity range is 100N from
Nov 23, 2004 1 of 5
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Terry,
I get a bit less as the minimum force sensitivity.
As I read the data sheet, the force sensitivity range is  <1N to  >100N

"Force is defined by Newton's second law as the product of mass and acceleration (F = m x a). The unit of force using the International System of Units (SI) or the metric system is the newton (N). ("Newton" is usually written as a lower-case word even though it is named after Sir Isaac Newton.) Mass is measured in kilograms (kg), and acceleration is measured in meters per seconds squared (meters/seconds2), such that 1 N = 1 kg x 1 m/s2."

if you substitute 9.8 m/Sec^2 for "a" in the equation ( acceleration due to gravity), I get a force equivalent to placing slightly over  a 102g  mass on the sensor as the minimum force, or about 3.6 ounces (at 28 g/ oz)

If you somehow arranged to measure pressure instead, the claim is 1.5psi to 150psi. since the sensor only has an area of .04 sq.in, that should give a sensitivity of  .06 lbs (a bit over twice that if they are counting both sides of the sensor). That's one or two ounces.

These measurements don't seem to jibe, so I question exactly what the data sheet is saying, especially since it says the device turn on force is 20g to 100g. (.7 to 3.57 oz)
Maybe they are just trying to say the devices vary a lot.

they are all under your 5/8 lb figure, though

Larry

In a message dated 11/22/04 10:17:30 PM Pacific Standard Time, sfrsa@yahoogroups.com writes:

These look like cool little sensors. I may get a pack just to
experiment with.

I'm still trying to get a handle on what you are trying to do. I
assume the FSR's are to be used as fingertip sensors. How are you
planning on connecting the feedback loop between the FSR and the
servo?

The amount of force you want to use to pick up and hold an object
depends on the weight, texture, and delicacy of the object. The
design of the hand can also have a significant effect. By my
calculations the minimum force that these sensors are designed to
detect is over 5/8 of a pound. Does this sound reasonable for your
application?

Terry

• Terry, depending what measure you use from the data sheet, the force the sensor will measure seems a bit less. According to the datasheet, The minimum force
Nov 23, 2004 1 of 5
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Terry,

depending what measure you use from the data sheet, the force the sensor will measure  seems a bit less.

According to the datasheet,

The minimum force sensitivity is given as 1 newton, or the force equvalent to about a 3.6 oz. weight placed on the sensor.

The minimum pressure sensitivity is 1.5 psi. Since the area of the sensor is .04", that should give a force of around.06 lb, or about 1 oz. --> Twice that, if they figure both sides of the sensor.

the minimum turn on force is given as  20 to 100 grams. (0.7 to 3.57 oz) .That about brackets the above figures.The range may be for the different size devices., the 400 being the smallest(biggest turn on force, or smallest?)

I'm not exactly sure how the datasheet writers took their measurements, but they are all under your 5/8 lb ( 10 oz) figure.

Larry

In a message dated 11/22/04 10:17:30 PM Pacific Standard Time, sfrsa@yahoogroups.com writes:
Message: 1
Date: Tue, 23 Nov 2004 06:07:49 -0000
From: "Terry Slocum" <tslocum@...>
Subject: Re: HELP!! Force Sensing Resistor

These look like cool little sensors. I may get a pack just to
experiment with.

I'm still trying to get a handle on what you are trying to do. I
assume the FSR's are to be used as fingertip sensors. How are you
planning on connecting the feedback loop between the FSR and the
servo?

The amount of force you want to use to pick up and hold an object
depends on the weight, texture, and delicacy of the object. The
design of the hand can also have a significant effect. By my
calculations the minimum force that these sensors are designed to
detect is over 5/8 of a pound. Does this sound reasonable for your
application?

Terry

• The data sheet won t open for me right now, so I can t check my calculations. Looking back at my calculators log, I think I may have used the diameter of the
Nov 25, 2004 1 of 5
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The data sheet won't open for me right now, so I can't check my
calculations. Looking back at my calculators log, I think I may have
used the diameter of the pad as a radius. Thanks for correcting my
mistake.

Terry

--- In sfrsa@yahoogroups.com, LJGeib@a... wrote:
>
> Terry,
>
> depending what measure you use from the data sheet, the force the
sensor
> will measure seems a bit less.
>
> According to the datasheet,
>
> The minimum force sensitivity is given as 1 newton, or the force
equvalent
> to about a 3.6 oz. weight placed on the sensor.
>
> The minimum pressure sensitivity is 1.5 psi. Since the area of
the sensor is
> .04", that should give a force of around.06 lb, or about 1 oz. --
> Twice
> that, if they figure both sides of the sensor.
>
> the minimum turn on force is given as 20 to 100 grams. (0.7 to
3.57 oz)
> .That about brackets the above figures.The range may be for the
different size
> devices., the 400 being the smallest(biggest turn on force, or
smallest?)
>
> I'm not exactly sure how the datasheet writers took their
measurements, but
> they are all under your 5/8 lb ( 10 oz) figure.
>
> Larry
>
>
> In a message dated 11/22/04 10:17:30 PM Pacific Standard Time,
> sfrsa@yahoogroups.com writes:
>
> Message: 1
> Date: Tue, 23 Nov 2004 06:07:49 -0000
> From: "Terry Slocum" <tslocum@p...>
> Subject: Re: HELP!! Force Sensing Resistor
>
>
>
> These look like cool little sensors. I may get a pack just to
> experiment with.
>
> I'm still trying to get a handle on what you are trying to do. I
> assume the FSR's are to be used as fingertip sensors. How are you
> planning on connecting the feedback loop between the FSR and the
> servo?
>
> The amount of force you want to use to pick up and hold an object
> depends on the weight, texture, and delicacy of the object. The
> design of the hand can also have a significant effect. By my
> calculations the minimum force that these sensors are designed to
> detect is over 5/8 of a pound. Does this sound reasonable for
your
> application?
>
> Terry
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