hi
i am looking to make a non contact or contact based position sensor to use as way to measure force in mN scale.
i am totally new to this field, and looking for suggestions about sensor selection. And most importantly, How do i know resolution of each sensor ? it is not given in tech files.
hi,
in the attached sketch , you can see what i am trying to do. Load cells with such high sensitivity and resolution upto 0.1mg are very expensive. and often unsuitable unless an even expensive rig is prepared for them. plus, there are many constrains that will effect the results.
in this sketch, 1,2,3, and grey boxes are showing possible location for sensor placement.
For measurement of thrust, What i am planning to do is to first measure displacement in the rig by placing known weights as simulated force. i.e. 1g, 0.5g etc. and plot a graph of displacement in mm or micro meter vs. force applied. and with this calibration graph, I will be able to measure thrust in mN range. Right now, I have not selected build material for rig, because what i have read in these forums is that, build material should be according to type of sensor.
From development kits, I have found is:
http://my.element14.com/texas-instruments/ldc1000evm/ldc1000-inductive-sensing-eval/dp/2360423
I think it may work in my case, but i wasnt sure about sensitivity and resolution of sensors installed in this module. And also, Is there any other sensor or accessory I may have purchase to make this module work ?
Other option I have is to use graphtec GL220 data logger with a sensor, but i am not sure if it will work directly with DAQ or not. My friend told me that i may have to build a controller unit to use properly.
In short, according to your experience, can you confirm if this module would work or not. and do I need additional components ?
out of 3 options for rig setup, which one you think will be best option.
How far can the sensing point move when the force is applied
less than 1mm. resolution of 1~10micron will be required.
What is applying the force
a MEMS based micro thruster, (micro rocket)
What resolution, accuracy, repeatability and hysteresis are acceptable
+-100 micro newton will be ideal. in terms of weight, 0.1mg will be okay.
repeatability within +-3~5% will be okay.
How fast must the sensor respond.
anything above 100Hz(100 samples per second) will be good.
but sadly in my case, budget is below 200USD, so i am trying to find alternate sensors which could do the job.
here is the attached diagram of original rig, which i am reproduce.
Original text "
Thrust measurement
A torsional thrust stand that resolves forces in the order of
micronewton was constructed in our center. This dedicated
thrust measurement facility was set up not only to evaluate
the performance of VLM but also for other micropropulsion
systems, e.g. a pulsed plasma thruster. A block diagram of
the actual setup is illustrated in figure 5. A detailed working
principle of a torsional thrust stand can be found elsewhere
[26, 27]. In general, our thrust stand consists of an aluminum
alloy beam of 60
cm long supported by a flexural pivot
(6012–400, Riverhawk) which provides the restoring force.
Beam deflection due to the VLM operation was measured
using a high precision optical linear displacement sensor
(ILD 2300–2, MicroEpsilon) which has a resolution of 0.03μm at 20
kHz measuring rate. An electrostatic calibrator
was used to generate consistent and repeatable calibration
force in order to establish the relationship between beam
deflection and force. The entire setup was covered by a
plexiglass protective box to reduce disturbances due to the
external environment.
Direct measurement of force from the VLM using the thrust
stand is difficult. Mounting of the liquid feedline on the thrust
stand surface has limited the thrust stand resolution [
13].
Alternatively, an indirect measurement technique was used.
A heater pad was installed on the thrust stand and heated to a
temperature of approximately 60
°C. The VLM was externally
mounted and aligned so that the vapor jets would impinge on
the surface of the heater pad. The heated surface prevented the
condensation of water vapor. The deflection of the thrust stand
due to the vapor jet impingement was recorded. The same
syringe pump and power supply were used for the operation
of VLM.".
How far can the sensing point move when the force is applied
less than 1mm. resolution of 1~10micron will be required.
What is applying the force
a MEMS based micro thruster, (micro rocket)
What resolution, accuracy, repeatability and hysteresis are acceptable
+-100 micro newton will be ideal. in terms of weight, 0.1mg will be okay.
repeatability within +-3~5% will be okay.
How fast must the sensor respond.
anything above 100Hz(100 samples per second) will be good.
but sadly in my case, budget is below 200USD, so i am trying to find alternate sensors which could do the job.
here is the attached diagram of original rig, which i am reproduce.
Original text "
Thrust measurement
A torsional thrust stand that resolves forces in the order of
micronewton was constructed in our center. This dedicated
thrust measurement facility was set up not only to evaluate
the performance of VLM but also for other micropropulsion
systems, e.g. a pulsed plasma thruster. A block diagram of
the actual setup is illustrated in figure 5. A detailed working
principle of a torsional thrust stand can be found elsewhere
[26, 27]. In general, our thrust stand consists of an aluminum
alloy beam of 60
cm long supported by a flexural pivot
(6012–400, Riverhawk) which provides the restoring force.
Beam deflection due to the VLM operation was measured
using a high precision optical linear displacement sensor
(ILD 2300–2, MicroEpsilon) which has a resolution of 0.03μm at 20
kHz measuring rate. An electrostatic calibrator
was used to generate consistent and repeatable calibration
force in order to establish the relationship between beam
deflection and force. The entire setup was covered by a
plexiglass protective box to reduce disturbances due to the
external environment.
Direct measurement of force from the VLM using the thrust
stand is difficult. Mounting of the liquid feedline on the thrust
stand surface has limited the thrust stand resolution [
13].
Alternatively, an indirect measurement technique was used.
A heater pad was installed on the thrust stand and heated to a
temperature of approximately 60
°C. The VLM was externally
mounted and aligned so that the vapor jets would impinge on
the surface of the heater pad. The heated surface prevented the
condensation of water vapor. The deflection of the thrust stand
due to the vapor jet impingement was recorded. The same
syringe pump and power supply were used for the operation
of VLM.".
