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How to Measure Force?

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mstechca

New Member
depends on the amount of force.

If you want to get cheezy about it, then you can measure the amount of sweat someone is exerting by picking up a ton of bricks by using a resistor that can detect heat (known as thermisitor). Tie the resistor to your body, make an analog to digital converter, and send the digital data to the computer using a serial port. This is a little difficult and an inaccurate method.

A weight scale with an LED display will do the trick. It measures weight.
 

sjaguar13

New Member
The force measuring thing is going to be punched.....a scale is kind of a good idea. A shipping scale comes with USB or serial connections. Would buying the force thing because cheaper than getting a shipping scale?
 

chemelec

Well-Known Member
You could buy a "Force Sensing Resistor", If Linearity and Accuracy isn't very important. Or Maybe Samples.

They are available from "Interlink Electronics".
Phone 805-484-1331
 

sjaguar13

New Member
Force Sensing Resistors seem like a good idea. One problem though, how do I get the analog input into my computer? Is there a way to convert it into USB?
 

Oznog

Active Member
It would be helpful if you begin by explaining exactly what it is you want to do. Force transducers (load cells) come in many schemes and they all have liabilities.
 

Oznog

Active Member
duplicate post
 

sjaguar13

New Member
I want to measure how powerful I can punch. It doesn't have to be deadly accurate as long as it is consistant. It has to show that after I finish the "Punching With Power" course that I actually increased power by at least 2 times. If it can't, I get a refund on the course. Plus, I think it's cool.

I would like to have the info go into Excel for easy graphing. I'm just not very good with the electronics stuff to take the resistance sensor and get it into my computer.
 

bryan1

Well-Known Member
This quote goes to show how much my wife knows about electronics. 'For a punch power indicator cut a watermelon in half and see how far you can punch into it'
 

Nigel Goodwin

Super Moderator
Most Helpful Member
sjaguar13 said:
I want to measure how powerful I can punch. It doesn't have to be deadly accurate as long as it is consistant. It has to show that after I finish the "Punching With Power" course that I actually increased power by at least 2 times. If it can't, I get a refund on the course. Plus, I think it's cool.
You can get air pressure sensors, these measure the pressure applied to them via a small pipe - you can feed the pipe from a rubber 'balloon' type of thing, mounted inside a punch bag or pad. The harder you punch the bag, the more air pressure applied to the sensor.
 

spuffock

Member
I assume you have a punchbag. If you set up two laser pointers and two photodiodes behind the bag such that when you hit it, it breaks first one beam then the other, then measuring the time between the breaks will give you an indication of the force. It will be very accurate as a relative measurement, and if you know the distance between the beams and the mass of the bag, you can calibrate it. Don't use ldrs, they're too damn slow.
 

lord loh.

Member
A Joke.

A Power Punch Course ??? Sounds Intresting. :)

All the posts remind me of a joke...

Nasruddin Hodja's friend was upset and visits Nasruddin and pours his problem to him.

Friend : When I was young, I was able to list the big rock in from of my house. Now that I have grown old I am unable to do so. :(

Nasruddin : Look at me!! I am as strong as ever! I was not able to list the boulder there ten years ago...And I still cannot lift it!
 

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Someone Electro

New Member
How about punching in a solid brick wall.The more it hurts the more force it was. (i dont recomend doing this whith your head)
 

DirtyLude

Well-Known Member
Nigel Goodwin said:
You can get air pressure sensors, these measure the pressure applied to them via a small pipe - you can feed the pipe from a rubber 'balloon' type of thing, mounted inside a punch bag or pad. The harder you punch the bag, the more air pressure applied to the sensor.
I think Nigel has the best idea. An Air Bag with a pressure sensor.

The simplest would be a microcontroller with an ADC just reading the values and sending the data RS-232. I don't think you would want to play with software to move it directly to Excel. Just copy and paste from a terminal program.

Any way you look at it, it's not going to be super easy. If you know nothing about electronics, and you really want this, I'd look at hiring someone, or finding a local geek to help you out with it. I'm sure there must be products out there that actually do this.
 

sjaguar13

New Member
When I originally got the idea for this, I searched google and found a paper written about the pressure way. They used a bag filled with water. My bag isn't water filled, so how would I get the pressure thing in there, cut the bag open?

Second, if you know of a system for sale, let me know.

Third, I was talking to a guy from a robotics forum and he might have a solution. The only problem is the connecting to a computer. Is there a way to have a usb send the data wirelessly to a computer without using a big box-like server, ie something I could put on the bag so there doesn't have to be a cable running from the bag to a computer?
 

Someone Electro

New Member
USB is realy dificult to do wierlesly.

It wod be beter to put an PIC MCU in the bag that comunicates whith an nother PIC that is conectd to your PCs serial port over those serial radio modules.
 
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