Hey, I would really like to know how you converted your readings from 1/R to C - Please could I see the circuit you made to do this? - Also, are you using an AC or DC supply? - What component model types did you use? I would really like to replicate this
Yes, the sensing area is flexible. It is quite sensitive; touching, bending, or looking at it in any way will change your readings. I had to run calibration routines regularly. It's sensitivity was quite high, as it would detect a gram of increased weight. I found repeatability to be very poor, however.
pvfjr Thanks for getting back to me. That's unfortunate.... I was looking for a piezo (or similar) sensor with a high repeatability. Do you know of any alternatives with a higher repeatability?
Raymond Chi Chung Yau I don't know of any better alternatives, sorry. I just made it work by writing a calibration routine that my microcontroller would run on power-up. It worked, but I just had to make sure that everything was in proper position when I powered up, otherwise the cal procedure would get thrown off. It was just more of an inconvenience than anything else. I think a lot of my issues stemmed from temperature fluctuations, as the worst performance I had was typically outdoors on partly sunny days. If I had had more time, I could have tried to characterize and compensate for the temperature changes, but who has time for that?
Syahril Arifin I don't think it would be very waterproof. I had one sensor delaminate a bit after being flexed a lot. While it didn't seem to affect functionality, it would easily allow for moisture intrusion. That said, I think new ones would allow for some sort term incidental contact with water. They are laminated between plastic films.
Haemant Ramkissoon Sure you could, as long as you make sure the peak of your impulse force is less than peak force rating of the sensor. That would depend, of course, on the elastic modulus of both your hammer and substrate, as well as the mass, length, and angular velocity of your hammer. It would be good to factor in the shape as well, accounting for peak pressures normalized by the expected contact area vs. that of the hammer face. If that doesn't make sense, then it's probably safest not to hammer on the sensors.
Paul Ferrigno Jr Well the type of hammer that is being used for the application is a 2.5kg hammer. The main pupose of this is to determine the force required to shape a steel sheet using hammering.
Haemant Ramkissoon That's a good, hefty hammer. I assume the steel sheet is of significant thickness then. The impulse forces produced with a hammer this size are very high, and would likely obliterate the sensor. I would recommend a couple different options. 1: Use a hydraulic press to slowly deform your sheet metal instead of a hammer. If you can tap into the slave cylinder of the press with a pressure gauge, then you can just take pressure times the bore size of the cylinder to come up with and equivalent force. 2: Attach an accelerometer to your hammer. If you can characterize the velocity and duration of impact, you may be able to extrapolate some reasonably accurate impulse forces. This method will probably contain a higher degree of error than the first method.
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Hey, I would really like to know how you converted your readings from 1/R to C
- Please could I see the circuit you made to do this?
- Also, are you using an AC or DC supply?
- What component model types did you use?
I would really like to replicate this
Hi there. For the 1lb. flexiforce sensor, do you have any idea oh how small of an acurate measurement can be made?
Hi there can you please send me the detail of sognal conditioning circuit if possible
Does anyone know if the 'Flexi' part include the load sensing area? will bending/flexing of the load sensing area cause fluctuations in the reading?
Yes, the sensing area is flexible. It is quite sensitive; touching, bending, or looking at it in any way will change your readings. I had to run calibration routines regularly. It's sensitivity was quite high, as it would detect a gram of increased weight. I found repeatability to be very poor, however.
pvfjr Thanks for getting back to me. That's unfortunate.... I was looking for a piezo (or similar) sensor with a high repeatability. Do you know of any alternatives with a higher repeatability?
Raymond Chi Chung Yau I don't know of any better alternatives, sorry. I just made it work by writing a calibration routine that my microcontroller would run on power-up. It worked, but I just had to make sure that everything was in proper position when I powered up, otherwise the cal procedure would get thrown off. It was just more of an inconvenience than anything else. I think a lot of my issues stemmed from temperature fluctuations, as the worst performance I had was typically outdoors on partly sunny days. If I had had more time, I could have tried to characterize and compensate for the temperature changes, but who has time for that?
is the flexiforce waterproof or not?
Syahril Arifin I don't think it would be very waterproof. I had one sensor delaminate a bit after being flexed a lot. While it didn't seem to affect functionality, it would easily allow for moisture intrusion. That said, I think new ones would allow for some sort term incidental contact with water. They are laminated between plastic films.
Hi, Does anyone know if i could hammer directly on the flexiforce sensor?
Haemant Ramkissoon Sure you could, as long as you make sure the peak of your impulse force is less than peak force rating of the sensor. That would depend, of course, on the elastic modulus of both your hammer and substrate, as well as the mass, length, and angular velocity of your hammer. It would be good to factor in the shape as well, accounting for peak pressures normalized by the expected contact area vs. that of the hammer face. If that doesn't make sense, then it's probably safest not to hammer on the sensors.
Paul Ferrigno Jr Well the type of hammer that is being used for the application is a 2.5kg hammer. The main pupose of this is to determine the force required to shape a steel sheet using hammering.
Haemant Ramkissoon That's a good, hefty hammer. I assume the steel sheet is of significant thickness then. The impulse forces produced with a hammer this size are very high, and would likely obliterate the sensor.
I would recommend a couple different options.
1: Use a hydraulic press to slowly deform your sheet metal instead of a hammer. If you can tap into the slave cylinder of the press with a pressure gauge, then you can just take pressure times the bore size of the cylinder to come up with and equivalent force.
2: Attach an accelerometer to your hammer. If you can characterize the velocity and duration of impact, you may be able to extrapolate some reasonably accurate impulse forces. This method will probably contain a higher degree of error than the first method.
No the steel sheet is just 1/16 thick. That's what I am unsure about before purchasing the sensor.