FLEXIFORCE VS SHUNT MODE - tekscan.com · Technology, Universiti Tun Hussein Onn Malaysia, 86400...
Transcript of FLEXIFORCE VS SHUNT MODE - tekscan.com · Technology, Universiti Tun Hussein Onn Malaysia, 86400...
In this test, FlexiForce sensors delivered the same force output when step loaded with three different puck diameters, whereas two shunt mode sensor types showed inconsistent output. This data indicates that shunt mode sensor output is a function of both load area and applied force. SU
MMARY
FLEXIFORCE™ VS SHUNT MODEFORCE SENSING TECHNOLOGIES
How Do They Compare On Key Performance Aspects?
NOT ALL FORCE SENSORS ARE CREATED EQUAL!There are important aspects to consider before making your tactile force sensor investment.
This graphic compares FlexiForce™ sensors (Thru Mode technology) against a similar tactile force sensor referred to as“Shunt Mode” technology. We will cover some specific differentiating aspects between these two technologies that
will be supported by verifiable, third-party data.
While FlexiForce proved to be the better alternative in these tests, every application has its own unique challenges and may produce different results. Whether as a standard sensor or custom solution, our team of expert engineers is standing by to find the right FlexiForce solution to achieve your needs.
See the full summary of data by visiting
www.tekscan.com/shunt-comparison
CHOOSE WISELY.
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REFERENCES:1Sadun, A.S., et. al. “Force Sensing Resistor (FSR): A Brief Overview and the Low Cost Sensor for Active Compliance Control.” (2016) Faculty of Engineering Technology, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat, Johor, Malaysia.2Vecchi, F. et. al. “Experimental Evaluation of Two Commercial Force Sensors for Applications in Biomechanics and Motor Control.” Advanced Robotics Technology and Systems Laboratory. Scuola Superiore di Sant’Anna via Carducci 40, 56127 Pisa, Italy.3Benbourenane, I. “Design of Nasal Endoscopy Simulator with Force Feedback” (2014) Human Movement and Balance Lab of the University of Pittsburgh.)
Shunt Mode Sensors
Polymer thick-film devices consisting of two membranes separated by a thin air gap.
Membrane 1 has two sets of interlaced traces electrically isolated from one another.
Membrane 2 is coated with a special textured, resistive ink.
When pressed, the ink shorts the traces together with a resistance that depends on the applied force.
HERE'S WHAT WE'RE
WORKING WITH.SO,
WHEN UNLOADED, RESISTANCE IS HIGH — WHEN PRESSED, RESISTANCE DROPS
According to manufacturer specs, FlexiForce can capture a wider range of force with greater accuracy than a majority of Shunt Mode force sensing resistors. The force range of FlexiForce sensors can also be adjusted to match the needs of the application.
FlexiForce Sensors (AKA, “Thru Mode Technology,” or “Piezoresistive Technology”)
Ultra-thin and flexible printed circuits consisting of two flexible substrates (polyester film).
Silver circles with traces are positioned above and below a pressure-sensitivelayer. This is the sensing area.
Conductive polymer is applied on each layer, followed by a pressuresensitive layer. Adhesive is usedto laminate the two layers of substrate.
FlexiForce Sensors
~0 N - 444.8 N (0 lb - 100 lb)with some sensors reaching
up to 44,482 N!
Most Shunt Mode Sensors
~0.2 N - 20 N(0 lb - 5 lb)
#4: DYNAMIC RANGE
#5: SENSING AREA DEPENDENCE
SUMMAR
Y
FlexiForce produced a more linear relationship in the two calibration tests. The Shunt Mode sensor appeared particularly non-linear within the 0-4 N force ranges.
#1: LINEARITY
SUMMAR
Y
FlexiForce was less susceptible to drift compared to the Shunt Mode sensor, whether loaded or placed into a controlled environment.
#2: SENSOR DRIFT
SUMMAR
Y
FlexiForce was significantly more accurate than Shunt Mode sensor at all three force ranges.
#3: DYNAMIC MEASUREMENT ACCURACY
SUMMAR
Y
FlexiForce Sensors (1) Shunt Mode Sensors (1)
CALIBRATION TEST 0-4 N (1)
CALIBRATION TEST 0-30 N (2)
TIME DRIFT DUE TO A 15 N LOAD (2) 12-HOUR RESISTANCE DRIFT AT 3V (3)
FlexiForceShunt Mode
Static calibration of FlexiForce and Shunt Mode sensors (with substrates)
FlexiForceShunt Mode
In this test, the subject wearing a device equipped with either FlexiForce or Shunt Mode sensors pinched a strain gauge dynamometer varying the exertion force five times over a 10-second period. The total error at each force level was computed as the difference between the force measured using the dynamometer and the force obtained from the sensor output.
REHABILITATION GRIP DEVICE TEST (2)
FlexiForce Sensors Shunt Mode Sensors
A FlexiForce A401 and an Shunt Mode sensor were placed in a tube for 12 hours. Voltage readings were recorded every minute.
OUTPUTTEDCONSTANT
VOLTAGE
DEGRADEDTO 0V AFTER
5 HOURS
12 HR12 HR0V 0V
3V 3V
Shun
t Mod
e O
utpu
t Vol
tage
(V)
Applied Force (N)
Flex
iFor
ce O
utpu
t Vol
tage
(V)
Applied Force (N)
Per
cen
tage
Err
or
(%)
0
1
2
3
4
5
6
7
Average Error (N) (2)
0-20 N 0-25 N 0-30 N
2.7%
4.7%
3.6%
4.9% 4.6%
5.9%
Per
cen
tage
Err
or
(%)
0
2
4
6
8
10
12
14
16
18
20
Maximum Error (N) (2)
0-20 N 0-25 N 0-30 N
7.4%
12.4%
9.9%
13%14.2%
19.6%
Per
cen
tage
Err
or
(%)
0
1
2
3
4
5
Standard Deviation (N) (2)
0-20 N 0-25 N 0-30 N
1.8%
3.1%2.4%
3.7% 3.6%
4.4%
FlexiForce Shunt Mode
100 lb
5 lb
Nor
mal
ized
Out
put f
rom
the
Sens
ors
Force Applied to the Sensors (N)
Per
cent
age
wit
h R
espe
ct to
the
Init
ial V
alue
Time (Minutes)
0.25
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
0.5 0.75
Vo
ltag
e (V
)
Puck Diameter (inches)
FlexiForce A401 Shunt Mode Sensor Brand 1 Shunt Mode Sensor Brand 2
Voltage Output at 5 lbs with Different Puck Diameters