Tekscan I-Scan System Start-Up for Reliable Pressure / Force / Area Data Collection

1. Tekscan I-Scan System Start-Upfor Reliable Pressure / Force / Area Data Collection Getting Started with I-Scan: Sensor Selection, Hardware and Software Sensor Conditioning Sensor Equilibration Sensor Calibration Data Collection May 2003

2. Is Tekscan’s Tactile, Thin-Film, Array-Based Pressure Measurement System Required for my Application? Yes, if your application demands the following: X and Y Pressure Distribution in Real Time Calibrated Magnitude of Pressure and Force (absolute and / or relative) Force Vs. Time / Pressure Vs. Time of an event (e.g. loading a fixture with a bolt torque sequence) Visual Location of High and Low Pressures in application interface Thin – Film Sensor (~ .004” +/- .0002” thin) Convenient method to measure, record, and even market results with graphs, ASCII output, 2D and 3D color views, save your recording as a ‘movie’ file (.fsx), and incorporate video synchronization

3. System Components • Sensor pad(s) • Sensor maps (software display drivers, each sensor has its own map) • Sensor handle(s) (A/D converter) w/ 12’ standard cable (30’ & 60’ avail.) • Plug-in PCI card (each PCI card can accommodate up to four sensor handles) • Expansion PCI unit (optional, convenient for a Notebook computer) • Tekscan Windows-based software (for most Windows OS) • IBM-Compatible PC • Color Printer (if color printouts are required) • System Notes • Tekscan Signal to Noise Ratio is much better than strain gauges (noisy) since our system has a resistance range from ~ 20 KOhm up to ~ 5 MOhm. • Dynamic response is a strong point for Tekscan • Ink response has been matched with an Instron up to 35 Hz perfectly • Requires an IBM-compatible computer; the more memory, processor speed, and available hard drive space the better. Ex. 300 MHz.to1GHz processor speed, 1GB to 40 GB RAM (memory), and a Hard Drive of 20 GB to 40 GB is an example a computer in line with the latest technology.

4. Will Tekscan Hardware Suit Application Environment? • Sensor handle cable lengths come in standard length of ~ 12 feet • Sensor handle standard maximum cable length is ~ 30 feet • Tekscan has tested up to 60 feet in a clean noise environment (~30 – ~ 60 Hz. max.) • Tekscan offers a Tab Extender / Clamp assembly which extends distance between sensor pad and sensor handle by ~ 18”. Tekscan needs to assemble. • Tekscan suggests protecting the handle in a ‘horse pill’ assembly for harsh environments. ‘Horse Pill’ offers sensor handle protection from water and drop damage; the ‘Horse Pill” is a plastic capsule which may be fabricated with a Dremel / Roto Zip • If noise is present, shielding the sensor with an electric ‘fence’ (conductive material) between the sensor and the noise source. The electric ‘fence’ should be firmly connected to the ground wire which is connected to the grounding screw on the sensor handle The ‘fence’ requires a high enough conductivity to adequately shield the sensor; however, the ‘fence’ must not be too heavy or thick as it will alter the physical pressure path of the application • Moving the sensor handle away from the noise source (isolating) will limit the effects of the noise since the amount of capacitive coupling is directly related to the distance of the noise source • Regarding water immersion, Tekscan sensors have been tested at 1 atm, 75 F while immersed in water for two hours without and adverse effects to sensor performance • The sensor pads have a temperature range of ~ - 35 F to ~ + 145 F.

5. Will Tekscan Hardware Suit Application Environment? cont. • Tekscan sensor pads measure compressive loads (perpendicular to the sensor pad) • Shear forces may damage the sensor and are not accurately measured • The largest active region on a sensor pad is 22.7” x 34.8” with .66” symmetrical spatial resolution • The smallest active region is ~ .5” x .5” • Data sampling speeds range from 1 Hz through ~ 10,000 Hz.; 10,000 Hz is achieved with sensor model 9550 coupled with High Speed version of software and hardware • Video Synchronization is an available add-on feature • Tekscan manufactures several equilibrator models (pneumatic bladders); most models have a max applied pressure of 100 PSI. One model achieves 500 PSI and another model reaches pressures of ~ 1000 PSI over a 5” x 5” area • Some applications require the customer to construct their own bladder (hydraulic or pneumatic) • Tekscan offers a Data-Logger which allows for remote data collection which may be downloaded at a later time. The F-Scan (in-shoe) is available and the I-Scan version should be available 1st Qtr. 2004 or sooner.

6. How to Select a Tekscan Sensor and System • Select the Proper Sensor Size • www.tekscan.com Industrial  Sensor Catalog • Load footprint should fall within sensor matrix (active area) • Custom Designed sensors are an option • Involves: • CAD electrical layout • Tooling (screens, dies) • Fabrication (printing, assembly, etc.) • Map development (unique software display) • Sensor Minimum Quantity • Initial PSAT testing • Final Product Testing (whole system) • Select the Proper Spatial Resolution • Refers to column center to column center and row center to row center spacing • Symmetrical and Asymmetrical spatial resolutions offered • 0.025” x 0.025” is the tightest spacing capability • Note: A single A/D converter accommodates 2288 sensels (52 columns x 44 rows) • Note: Eight A/D converters is the limit for a single sensor pad • To maintain a fairly tight spatial resolution (ex. 0.060”) over a large area (e.g. 10.6” x 11.6”), multiple sensor handles are required on the same sensor pad

7. Select the Proper Sampling Speed • 127 Hz (frames / sec.) standard. Each sensel is sampled 127 times / sec. • Highest speed is 10,000 Hz (using 9550 model only) • A sensor pad with ~ 33,000 points will yield ~ < 32 Hz (model 8050) • A sensor pad with ~ 8,500 points will yield ~ < 63 Hz (model 8000) • The number of sensor handles, rows, and total sensels affects sampling speed Pre-Triggering / Triggering – Pre-triggering is available; it is a circular buffer which will store frames of data before the Trigger point. Triggering is also a software feature whereby you can select a ‘Start’ threshold and an ‘End’ threshold. The software will automatically Start and Stop based upon your threshold requirements.

8. Select the Proper Sampling Speed cont. • High Speed System with Multiple Handles for a Tekscan PCI card (frequencies may be slightly higher)

9. Select the Proper Sampling Speed cont. Example: High Speed timing for the 5315 sensor pad • Max data acquisition speed: ~ 216 Hz. (2016 total sensels) / dependent upon total sensels • Time to record one frame: 1 / 216 = 0.0046 sec • 52 driven traces: • Time to collect data from 1 driven line = 0.0046 / 52 = 8.84 E-5 sec • This time is broken into 64 time units: • 8.84 E-5 / 64 = 1.38 E-6 • Scanning time for a driven line: • Driven line needs 12 time units to apply voltage and let settle enough • (12) (1.38E-6 ) = 1.65E-5 • After driven line is charged, all 44 intersecting rows are read sequentially The time it takes to read one sensel is one time unit, 1.38E-6. Time to read all 44 sensed traces  (44) (1.38E-6) = 6.08E-5 • The driven trace needs to be grounded. • This takes eight time units. (8) (1.38E-6) = 1.10E-5 • 12+44+8=64 Time Units Then the sequence starts over with the next driven pogo pin / trace; the driven pads / traces are charged (activated) in sequence even if there are no traces physically connected to the pogo pin / pad / trace. Driven traces start at 0 and end at 51 while sensed traces start at 0 and end at 43.

10. Select the Proper Sensor Full Scale Pressure Range - Select a full scale pressure range (PSAT – saturation pressure) slightly higher than the application’s maximum pressure to account for any pressure peaks. - Note: Most Tekscan “55XX” (Nip / Pinch) sensor models have limited or no standard pressure ranges - Custom full scale pressure ranges are feasible; there are some exceptions based upon sensel size, row and column lengths, and other variables. - During a trial experiment, load the sensor similarly to the application and have the Color Pressure Legend open and set to 0 to 255 (Tekscan’s eight-bit full raw digital output scale). The maximum sensel output is 255 Raw DO (Digital Output). The application pressure should nearly saturate the sensor output. Ex. If ~ 240 DO is shown to be the peak pressure in the experiment, then the optimum sensor full scale range has been selected. If a sensel reaches DO of 255, the load on it can double or increase by a factor of ten, and no greater output will result. Note: Before conditioning, equilibrating, or calibration, it is recommended to check that all components are connected properly. You can press with your finger or a stylus to ensure the sensor responds appropriately. Apply pressure at column end to see if any rows are shorted or open electrically, If you see red along a row or column, the row or column may be electrically shorted. If you do not see any color except black, then an open may be present. Always reseat the sensor and try again. “Sensor OK” should be visible in the lower Real Time window bar.

11. Conditioning the Sensor Pad • Using, Tekscan’s equilibrator unit may be used since it imparts a uniform load pneumatically. Most Tekscan equilibrator’s have a capacity up to 100 PSI. Maintaining similar temperature during conditioning is important. Mimic the interface profile if feasible (i.e. roller ) and impart similar pressure as in the application, condition the sensor for three cycles at ~ 30 seconds per cycle at ~ 115% / ~ 120% higher than the application pressure. • If Tekscan’s equilibrator is not feasible or available, try to implement two metal plates with a sheet of urethane foam in between; ensure the foam is not too soft such that it “squirms” markedly on the sensor surface. • Conditioning the sensor pad minimizes drift, hysteresis, and improves repeatability. • Tekscan manufactures several equilibrators (pneumatic and one electric / hydraulic). The 0.025” thick urethane bladder applies a uniform pressure to the sensor pad via clean, dry, shop air. An analog pressure gauge, external pressure regulator (three-position toggle switch), and plastic tubing are included as well as a pressure relief valve. Some models are constructed from wood and some from aluminum. Some models incorporate OHAUS calibrated weights to apply pressure. • Tekscan offers a cylindrical bladder which pressurizes up to ~ 600 PSI as well as a hydraulic bladder with 5.0” x 5.0” active area and 0.5” corner radii – to fit 5101 model and smaller. One side of sensor must be peeled to fit. This bladder will be rated to ~ 1000 PSI and will be pumped via a hand or foot pump.

12. Sensor Equilibration - Equilibration should be performed before calibration. -Tekscan offers up to a ten-point equilibration -In general, a sensor’s output (sensitivity) will exhibit a decrease over time, which the Tekscan system can measure; this decrease occurs during use and is a function of the loading conditions. A good application for equilibration, is when the sensor may loaded repeatedly in the same physical location on the sensor pad. Typically, the unloaded region of the sensor pad remains intact, that is it holds a higher sensitivity than the loaded region. Equilibration compensates for for the sensor’s trends thus provides a more even sensor sensitivity. - Also, loading the sensor pad with rough, heavy textured materials will change the sensitivity of each sensing element as the sensels are loaded repeatedly. In this case, the unevenness of the sensor’s sensitivity would be more random and would not produce a visible ‘trend’ as the case where the sensor is loaded in the same physical region each time. - An equilibration file may be loaded before or after the new recording - If performing a single-point equilibration, the max pressure of interest should be selected; this may be the range mid-point or an average Digital Output such as 125. - Applying a uniform pressure with a bladder device is a means of inspecting the proper sensor operation / damage. - Scale factors range from 0.5 to 2 and the scale factor is unique to each sensel and equilibration level (pressure).

13. Sensor Equilibration cont. • The Black and White image in the equilibration dialog window represents: - cold (not as sensitive sensels) with black-ish color - hot (more sensitive sensels) with gray-ish color The sensels with light gray-ish color represents equilibration factor values close to 0.5 The sensels with black-ish color represents equilibration factor values close to 2.0 • The average Digital Output is not affected by equilibration • Sensels with low output receive more gain to increase their Digital Output and sensels with high output have their gain reduced to lower their Digital Output. Electronic compensation for each individual sensel to sensel sensitivity difference, due to manufacturing or history of use, is accomplished • Ensure that there is not trapped air inside the sensor which will give the ‘pillow effect’. Sensors may be loaded a portion at a time in order to ‘milk’ any air out from inside.

14. Describing the Equilibration Process: Tekscan’s pressure bladder (equilibrator) is useful in equilibrating a sensor. Equilibration is the process of normalizing the output of each sensel (sensing point on the sensor matrix region) to the average output of all the sensels on the pad. This is accomplished by applying a known uniform pressure to all the sensels and allowing the software to define a scale factor, which is applied to each sensel, resulting in a uniform output at that pressure. The bladder device applies the known uniform pressure. This bladder may be used to equilibrate and calibrate (in some cases). In general, a sensor’s output or sensitivity will exhibit a decrease over time, which the Tekscan system can measure; this decrease occurs during use and is a function of the loading conditions. One good application for the bladder device is when the sensor may be loaded in the same location each time. Typically, the unloaded regions remain intact but the loaded sensels may degrade over the life of the sensor. Equilibration compensates the sensor’s trends thus providing a more even sensor sensitivity. The bladder device is also beneficial in cases where the interface materials applying the load are rough and have a heavy texture. This will change the sensitivity of each sensing element as the sensels are loaded repeatedly. The unevenness of the sensor’s sensitivity in this example would be more random and would not produce a visible ‘trend’ as the case where the sensor is loaded the same each time.

15. Single Point Equilibration A uniform pressure is applied to the sensor pad surface typically by one of several Tekscan equilibrators; a 0.025” thick urethane bladder is pneumatically filled with clean, dry, shop air which runs through our external pressure regulator and plastic tubing. The average raw digital output of all the sensels is calculated and then a matrix of normalization factors is derived and then applied to each respective sensel so a uniform corrected output is given for a uniform input with higher or lower pressure input than the single point equilibration point, uniformity output is expected to be improved by equilibration. Equilibration is typically performed at the pressure of the test of interest. Single-point equilibration uses a scale factor based upon the Digital Output average of all the sensels at the single pressure point. The scale factor is individual for each sensel.

16. Multi-Point Equilibration –Offers the advantage of compensating for sensel output over the full operating range. A piece-wise linear approach is implemented to normalize raw digital data on a sensel by sensel basis. Multi-point equilibration treats each sensel individually; for each sensel, a different slope exists with incremental increase of raw digital output. Tekscan allows up to a ten-point equilibration. Technical definition: Interpolation between inflection points of a piece-wise linear curve; inflection points refer to Digital Output average of all the sensels at one pressure point. Example: Three Sensel Values 1st Equilibration Point: 10, 16, 22 2nd Equilibration Point: 26,30,34 3rd Equilibration Point: 34,36,38 Average is taken for each equilibration point 1st Equilibration Point: [10+16+22} / 3 = 16 2nd Equilibration Point: [26+30+34] / 3 = 30 3rd Equilibration Point: [34+36+38] / 3 = 36 Scale Factor is Applied to Each Sensel 1st Equilibration Point: 16/10 cold, 16/16 linear, 16/22 hot 2nd Equilibration Point: 30/26 cold, 30/30 linear, 30/34 hot 3rd Equilibration Point: 36/34 cold, 36/36 linear, 36 / 38 hot

17. Multi-Point Equilibration Example cont. Step-Wise Linear Curve Coordinates 1st Equilibration Points: x = 10, y = 16 x = 26, y = 30 x = 34, y = 36 2nd Equilibration Points: x = 16, y = 16 x = 30, y = 30 x = 36, y = 36 3rd Equilibration Points x = 22, y = 16 x = 34, y = 30 x = 36, y = 36 I.E. Raw Input of x = 18, coordinates used would need to be: x = 10, y = 16 x = 26, y = 30

18. Multi-Point Equilibration cont. - The zero point is always an equilibration point - A separate ‘piece-wise equilibration-curve’ is defined for each sensel - An average digital value is found for each equilibration pressure (point) - The actual digital value for each equilibrated sensel is saved - If a sensel is not active at an equilibration pressure (point), then the overall average digital value is used as the ‘actual’ digital value - The highest two points are linearly extrapolated to determine the line beyond the highest pressure (point) - Works with a two-point calibration Example: Application pressure range is 0 to 100 PSI A multi-point equilibration may be implemented; equilibration points may be: 20 PSI, 40 PSI, 60 PSI, 80 PSI, 100 PSI (Five-Point Equilibration)

19. Application Parameters to Mimic for Calibration: Material Interface – Application material interface should be implemented during calibration. The same durometer rubber is very important as our sensor has a topography which is sensitive to different durometers. Sometimes our equilibrator is used for both equilibration and calibration. Applied load = area loaded x PSI gauge. Ensure that no trapped air inside the sensor is acting as an air buffer when using the bladder; you will see a low / no load area where there should be load. Interface Profile – If at all possible try to mimic the profile of the interface. Ex. If the interface is a roller to roller, load the roller profile and material onto the sensor pad. I recommend comparing a flat stock and profile calibration in this case. Temperature – Keep the temperature in your calibration similar to that of the application. In some cases, a person’s body temperature needs to be replicated, such as in seating applications. For every degree F the calibration temperature differs from the application, the sensor reading will be off by ~ .25%. Note: In an automotive seat application, where a person’s body temperature can affect the sensor output, you should calibrate at a temperature close to 98.6 o F. Timing - To minimize the effects of drift, mimic the time of the application in the calibration within reason. That is if the measurement will be for 30 minutes of recording, you may wish to calibrate for ~ 2 minutes. Our system’s drift curve levels off after ~ 30 seconds and then our 3% per log time is effective. One can record a loading in raw digital output and then open a Force Vs. Time graph to view the curve to see where it begins to level off. Where the curve levels off (stabilizes) is a good indication at the time interval needed for calibration.

20. Sensor Calibration Notes: Calibration converts the raw 8-bit digital output (0 – 255 per sensel) into engineering units such as Pounds, Newtons, Kilograms, etc. (Force) and PSI, Kg-Cm2, etc. (Pressure). The Tekscan reported calibrated data should be periodically compared to a known, reference load to ensure the Tekscan calibration is still within its +/- 10% range. A solid calibration will mimic the actual application in terms of temperature, material interface, interface profile (application dependent), timing of test, and loading characteristics (i.e. how the load is applied). I-Scan uses the force imparted on the sensor pad as the calibration value; the loaded area is automatically detected by the software. The pressure / pressure distribution is calculated from the applied force and detected area. Each row and column intersection is a sensel (variable resistor) with a resistive range from < 10 MegaOhms down to ~ 20 KOhms. Calibration converts a known load’s impedance into engineering units. A good calibration will result in good data reporting. Tekscan’s pneumatic bladder, in some applications, may be suitable for calibration in addition to equilibration based upon the material interface on the sensor pad TARE Feature – Only works after a single-point or a two-point calibration has been performed. Allows user to Tare out undesired preload. Ensure the two points in the two- point calibration are close to linear.

21. Sensor Calibration Notes cont. High Speed Post Calibration – You can perform a post-calibration (after the recording) by utilizing the Force Vs. Time graph and applying the calibration to the highest force point as shown by the graph as long as that force is known. Regular SpeedPost Calibration – One may calibrate the sensor after the data is recorded by utilizing the Force Vs. Time graph or one may apply a different calibration file as long as the new calibration was performed with the same sensor model. One must know the force acting through the sensor for at least one frame in order to use post-cal. Sensor Loading - Ensure the load is balanced and stable before calibrating or testing Ensure when the sensor is loaded, that the sensor is not reporting mostly red colors nor mostly blue colors; this would indicate the sensor is either too sensitive (red) or not sensitive enough (blue). If mostly blue colors or orange / red colors are displayed with our pressure legend set to full scale (0 to 255), then the sensor needs to be physically changed out for a more suitable full scale range such that at full load the display reports greens / yellows / oranges (3/4 of full scale allowing for any pressure peaks). Physically load sensor in calibration fixture similarly as in the application. Calibration pressure should be similar to application pressure. Preferably, load the entire matrix area during calibration. Be careful no to overhang the load off the sensor; you may need to shim if this is the case. A load frame such as an Instron, Tinius Olsen, MTS may be implemented for high loads. Ensure the plates are free to engage in a parallel manner.Load at least 25% of the active area for good statistical data.

22. Sensor Calibration Notes cont. Ensure the entire calibration load is transversing through the active sensor region and not bridging the sensor non-sensing edges. Load at least 25% of the entire sensor active area. Ensure sensels are not saturated (red); if a sensel(s) is saturated it no longer add to any increase in load thus a poor calibration will be accomplished if red sensels are present. Mimic timing of application load since our sensors experience drift (3% per log time) Most drift occurs in the first 30 seconds of loading. Example of drift: 1 sec = 100 lbs. 10 secs = 103 lbs. 100 secs = 106 lbs. 1000 secs = 109 lbs. 10,000 secs = 112 lbs. Impact load calibration: Example – pendulum device for calibrating the force on the chest of an automotive crash dummy is used since the mass of the pendulum is known and the acceleration is known from an accelerometer in the dummy, thus the force can be calculated. Editing a Single-Point or Two-Point Calibrationis easily accomplished through the edit feature.

23. Sensor Calibration Notes cont. % Active Sensing Area Vs. % Inactive Sensing Area - the less Inactive sensing area % , the higher the output with a rubber material will be as compared to a sensor with more % active area. The sensor with higher % inactive area will allow more off-loading of a rubber material than a sensor with a smaller % of inactive area. It is important not only to replicate application materials during calibration but also to think about Sensor Stacking - Do not calibrate sensors stacked upon each other. Metal Plates - When loading two linear surfaces (e.g. two plates of steel), it is Recommended to insert a sheet of paper or a thin urethane sheet between the two plates. Rubber Parts - When loading a rubber part onto the sensor, a thin sheet of teflon paper works well to minimize shear forces which are not measured by our sensor. Our sensors measure compressive forces. Soft Interfaces - When loading a crash dummy or a person onto a foam / cushion, try to calibrate with the actual materials and with the actual profiles / curvature. CAUTION needs to be taken. For example, when sitting in a luxury automotive seat, the sensor will bend upward on the sides thus introducing horizontal loads which can give you misleading data. Some customers elect to use the equilibrator even though the material interface inside the equilibrator differs from the actual application; the equilibrator offers relative repeatability

24. Sensor Calibration Notes cont. Changing Area – In some applications, such as tire and seating, the area increases with increased load thus keeping the pressure fairly constant which makes a two-point calibration difficult since the algorithm tends to “blow-up” when the two pressures are too close in value. The two forces should be ~ 20 % apart. Saturated Sensels – You do not want to have all / mostly blue sensels or all / mostly red sensels appearing on your display before you engage a calibration. If you have many red sensels (255) you are saturated and you will not be able to resolve those points on the sensor in the application and if you have all / mostly blue sensels on your computer screen display, you will not be leveraging the best pressure measurement resolution you could be with that given sensor’s saturation pressure (PSAT). Ideally, you would want to see some yellow, orange, green, and blue colors on your display (sensor pad) before calibrating. You may need to adjust the physical sensor for a more or less sensitive pressure range in order to find the ideal range for the application. Overall System Accuracy - +/- 10% of full scale (~ labeled saturation pressure on physical sensor) Material Dependency - Do not assume that +/- 10% of the labeled PSAT on the physical sensor will give you overall accuracy, since the sensor pads are very material dependent. Different durometers will offload unlike a flat piece of steel; Sensel offloading is dependent upon the % active sensor area Vs. % inactive sensor area. Pressure Measurement Resolution – [ Saturation Pressure (PSAT) /255 ] Cal Files – You may generate and save many cal files for a given sensor and can load those files in the future as long as you apply the cal files to that same physical sensor with which you calibrated and recorded.

25. Sensor Calibration Notes cont. Pressure Color Legend – Ensure the pressure legend is Open and set to full scale (0 to 255) before calibrating or simply for testing to see if the sensor PSAT range is suitable. Load Frame - Ensure the load frame (e.g. Inston, Tinius Olsen, etc.) is calibrated and the plates load in a parallel manner. Multi-Tile Calibration -If a multi-handle system (e.g. four handles each with their own sensor such as four 5051 pads) is being used, one may calibrate each sensor individually or calibrate all four simultaneously. If a four pad sensor is being used (e.g. 6900 model), one may calibrate each sensor pad individually or calibrate all four simultaneously. Requires Tekscan software version 5.10 or later. White lines (‘boxes’) in Calibration Dialog Window - Where the white lines / ‘boxes’ intersect the calibration curve represent(s) the average raw(s) in the calibration point(s); this is true whether it is a single or two-point calibration.

26. Single Point Calibration - Uses the following equation: Digital Output (Global Scale Factor) * Entered Force ----------------------- = -------------------- # of Sensels Loaded Area Loaded Typically implemented when the application’s range of loads to be measured is small (within +/10% of the calibration load) or when the maximum load is small (< 500 to 1000 psi) Typically implemented whensystem is linear; the system is linear if the sensor digital output difference between each loading increment is similar. Calibration Force -Calibrate at a pressure which reflects the working pressure / pressure of interest in the application. For example, it is not recommended to calibrate at 100 psi when you are interested in data at 10 PSI. One should select a sensor’s full scale range which allows enough headroom for unexpected pressure peaks. Take the area into consideration so the calibration pressure is similar to the actual application pressure. The single-point calibration is good for ~ +/- 20% of the single calibration point. The white line(s) in the calibration dialog window graph represent(s) the average raw output(s) of the calibration point(s).

27. Two-Point Calibration –Typically implemented when application is non-linear and / or when a wide pressure range of interest is required (~ > 1000 PSI). The two-point calibration utilizes a sophisticated algorithm which accounts for distribution through a ‘histogram’ method. The two-point algorithm includes zero load to solve for the two constants in the exponential Power Law equation. Y = Axb Y = force / load A = scale factor x = digital output (raw value) b = constant, determines slope Equations implemented: Force 1 = [n1 * 1b + n2 * 2b + n3 * 3b + … + n255 * 255b] Force 2 = [m1 * 1b + m2 * 2b + m3 * 3b + … + m255 * 255b] n1 through n255 = # of sensels with digital raw values of 1…255 in the first cal point m1 through m255 = # of sensels with digital raw values of 1…255 in the second cal point The iteration for “b” occurs ten times; the iteration is topped if Force 1 / Force 2 is “close” to: [n1 * 1b + n2 * 2b + n3 * 3b + … + n255 * 255b] -------------------------------------------------------------- [m1 * 1b + m2 * 2b + m3 * 3b + … + m255 * 255b] When “b” is solved, it is substituted back into each of the two equations in order for constant “a” to be solved. If the system is linear, the value of “b” will = 1. If the two pressure distributions are too similar, “b” is not solved for very well. The two pressures need to be three times apart from each other. The DIFFERENCE between [ Force 1 / Force 2 ] and [nx^b / mx^b] should be < 0.001

28. Two-Point Calibration cont. Two Loads / Forces – must be known and must generate different pressures; if the pressures of the two applied loads are too close to each other, the algorithm may not function. A rule of thumb is to have the two pressures be ~ three times apart. Do not saturate sensels during calibration (saturated sensels are technically red-colored sensels with a value of 255; I recommend no red-colored sensels present during calibration). The algorithm “blows up” when the exponent (“b”) > 4. Typically, the Exponent, “b”, is > 4 when a nonlinear material is used such as a rubber ‘puck’. A rough guideline for selecting the two points are 20% and 80% of the actual force; ensure you do not have saturated sensels (red colored sensels). Note: “b” (exponent) values may be found @ Options  Settings  Calibration  EXPONENT 0.5 to 2.0 is a reasonable (real life) range for “b”. If “b” values are < 0.5 and > 2.0 one can be suspicious. “b” values of 2.0 for a uniformly loaded sensor with a moderate Digital Output could be OK. Histogram – Each of the two equations break out the distribution of data. For example, 100 sensels at 100 digital output, 50 sensels at 101 digital output, 33 sensels at 102 digital output, etc. Calibration Window Graph – In the graph, the calibration curve may not pass through both calibration points due to a possible histogram shift; the mean is not always equal to the mode / median.

29. Two-Point Calibration cont. - Tare feature (located in calibration dialog box): Large tae values coupled with a non-linear calibration will cause errors. There is not an issue for a single-point linear calibration. 3% min. of sensles is required. - Changing Areas When performing a two-point calibration, one may experience that the second load is similar in pressure to the first load due to the fact that the area increased as the second load point was applied. This will result in an Error Message saying the Two-Point Calibration failed. - Varying Loads in the same recording Example: Railroad Tie Plate : Rail Interface application. The locomotive will impart a higher force than the passenger cars since the locomotive is much heavier. Your Force Vs. Time graph will have similar passenger car peaks and a much higher locomotive peak. Post Calibrate – use similar material interface, temperature, and timing if possible on a load frame (MTS / Instron, Tinious Olsen, etc.) for imparting the calibration force. Your options are: One-point calibration at the high peak One-point calibration a low peak One-point calibration; [average of low peaks] and [single high peak] Two-point calibration; try one point at a low peak and the other point at high peak Two-point calibration; [average of low peaks] and [the high peak itself] OR Repeat test with one sensor full scale pressure range suited for the passenger cars (all similar force peaks) and another sensor suited for the locomotive. You would perform the test twice in the same assembly; one time with a sensor range for the passenger cars and the next time with the sensor suited for the locomotive. OR Insert the two sensors in the assembly in their respective interface (so not to have to reinstall second sensor if sensor installation is time consuming or difficult. Determine if stack-up of two sensors (` 0.008”) will affect test. Take one recording which captures both high and low peaks. Use Edit feature to cut the high peak portion from the reocrding. Save. Take another recording which again will capture the low peaks and the higher locomotive peak. Use Edit feature and cut the lower peaks (passenger cars) form the recording.

30. Sensor & Application Tips / Software Features - Lubrication may be achieved for shear force reduction via baby powder, teflon paper, spray lubricant. • Peel sensor protective layer before using the 6220 / 6230 sensor models • Implement a sheet of regular paper, clean room wipes, or possibly silicone foam when measuring between two metal plates. Spacer should not be too thick. • Use 3M’s Adhesive 77 when fastening sensor to a surface. Spray evenly and lightly. No clumps should be present or a pressure artifact will exist. • Prevent sensor connector bank from getting caught inside handle by peeling protective layer back from near connector bank assembly • Minimize sensor wrinkling and sharp bending as this will introduce artifact and prematurely wear the sensor. • Right angle in application: use two sensors • Clean sensor after use by wiping down sensor after each application with a damp rag / alcohol and store safely and flat (horizontal for large sensor pads) at room temperature in a protective case. • Measure from several sensor pads with a single handle by positioning sensor pads between a mating surface and measured one at a time by clipping and unclipping the sensor handle down the line while taking a SNAPSHOT while connected to each sensor pad. • Rectangular-shaped sensels are well suited for line contact (nip / pinch) – Pounds per Lineal Inch (PLI) and Square-shaped sensel for area contact (PSI). • Shims may be used if the hard : hard interface overhangs the sensor • Applications using vacuum: our software was not written for resistance levels > 5 Mega Ohm. If vacuum causes a material to compress onto our sensor there may be a possible correlation.

31. Sensor & Application Tips / Software Features cont. - Placing one sensor model (PSAT ‘A’) on top of the same sensor model (PSAT ‘B’) in order to obtain the best possible pressure measurement resolution for an application which has a wide range is typically not done, rather two sensors, each with a different PSAT, are implemented separately. Dynamic seating applications such as a foam automotive seat whereby a driver is driving at a fair rate of speed over bumps, have many variables such as, foam density, seat design, sensor deformation, non-linear material behavior on our sensor, and data sampling speed up to ~ 225Hz. Further testing at the customer facility is required for this type of application. - The % of sensor inactive area (dead space) VS. the % of sensor active area will influence how non-linear materials behave (e.g. rubber material such as a mouse pad durometer). A sensor with a large active area and a very small inactive area will yield more force output than a sensor pad with a smaller % of active area and a higher % of inactive area. - If tape is used to secure the sensor, be careful not to tape over the active region of the sensor since a pressure artifact will be created. If you trim the sensor, protect the exposed inner portion of the sensor from any dirt or liquid from entering the sensor. Usually a piece of tape works well. - A ‘horse pill’ may be implemented to protect the sensor from water / drop damage; the ‘horse pill’ is a plastic capsule which may need to be fabricated with a Dremel / Roto Zip tool.

32. Sensor & Application Tips / Software Features cont. • Nip / Pinch (roller) applications - If the line contact is narrower than the sensor pad row and a flat plate calibration is performed, strange results most likely occur. So, it is recommended to calibrate with a line contact and ensure the calibrated row is placed under the nip for the measurement. If nip is wider than the sensor pad row, calibrating with a flat stock to obtain statistically representative data is suggested.Calibrating on one region of the sensor and measuring from another region will compromise results / performance. Sensor models 5501, 5560, 5570, and 5580 have wide rows (roller contact should fall within this wide row). Force will be accurate; however, pressure will be inaccurate since the load is a narrow line. Example: 5580 has a 1/8” wide nip loaded on itself in the machine direction. The row spacing is 0.54” and column spacing is 0.24” which gives a sensel area = 0.1296 square inches. A sensel reading of 20 PSI yields a force = 20 PSI * 0.1296 square inches = 2.592 lbs. This force acts over 0.24” (axis direction) yielding 10.8 PLI. The force acts over 0.125”, which is 1/8”, in the machine direction giving an average pressure of (2.592 lbs.) / (0.125” * 0.24”) = 86 PSI. Most nip pressures have a peak pressure twice that of the average pressure, so about 172 PSI would be the expected peak pressure. Utilizing nip sensors with a high spatial resolution (e.g. 5526) most likely would be a better choice for narrow nips.

34. Nip / Pinch (roller) application example cont. – Curved Contact Surfaces may be measured with Tekscan’s sensor models 6900, 9801, or 9830 since they have narrow sensing areas which lend themselves to positioning on contoured surfaces with minimal artifact generated from the geometry. Other sensor models will detect side forces generated as in an automotive or office chair with side bolsters. Tekscan sensors respond to the individual local normal forces, thus a seat design whereby side forces are generated will contribute to the total load the sensor reports even though the load is technically not perpendicular to the sensor.

35. Sensor & Application Tips / Software Features cont. Using Sensor in a Wet Environment– I have found a ‘Horse Pill’ capsule which will assist in wet environments. Using Sensor on a Contoured Curve – Tekscan has designed narrow sensors (‘fingers’) such as the 6900 and the 9801 / 9830 which lend themselves to contoured surfaces in that the effects of the curve are minimized. ASCII Data– May be exported very easily in two different formats Web Demo– Allows Tekscan to run our system while a prospect views the computer screen of the Tekscan engineer giving the web demo Verify Pressure Pattern – Rotate sensor pad and if ‘anomaly’ follows sensor then it is a ‘bad’ sensor. If ‘anomaly’ stays in the same location, then it is from the part being tested Virtual Maps - In order to create a real-time window with a virtual map in our software, you definitely need to have as many handles connected as are required for the virtual map. Group Recordings – Allows recording of groups of frames as a single ‘movie’ using multiple start and stop events.The software will continue to stop and start recording based upon the selected triggering events until manually stopped or frames specified is reached.

36. Sensor & Application Tips / Software Features cont. ASR (Automatic Sequential Recording) – Allows a new recording to automatically start when the current one is complete, without the need to manually open new real-time windows and start new recordings. The software would automatically save and close the current movie, open a new Real-time window, and begin a new recording. This will continue until stopped manually or until the total frame count is reached. Drift –The sensor exhibits drift with an applied constant load. The drift is ~ 3% per log time. If a 100 pound load is applied to the sensor, after 1 second the load would read ~ 100 pounds, after 10 seconds the load would read ~ 103 pounds, after 100 seconds the load would read ~ 106 pounds, and after 1000 seconds the load would read ~ 109 pounds. Since most drift occurs at the beginning of the loading period, it is suggested to calibrate ~ 30 seconds after the load is applied or longer. Impact loads (High Speed) may be calibrated after the recording with our Post Calibration software feature.

37. Sensor & Application Tips / Software Features cont. TARE Feature – Only works after a single-point or a two-point calibration has been performed. Allows user to Tare out undesired preload. Ensure the two points in the two-point calibration are close to linear. 3% minimum of sensels is required. TARE Example:3” diameter (circular) image is the preload whereby all 200 sensels which comprise this circular image are all blue in color (assume the same shade of blue thus the same raw count for each sensel). I wish to TARE all 200 sensels, that is completely remove them so they do not factor into my measurement calculations. Assume each of the 200 sensels have a raw count value of 40. A TARE will reduce the value of each of the 200 sensels. Since the max output of each sensel is 255, the reduced value of each of the 200 sensels will be 255 – 40 = 215. 215 becomes the equivalent of ‘255’, thus 215 is the ‘new’ saturating point for the 200 sensels. Pressure Measurement ResolutionThe I-Scan handle has an 8-bit A/D converter which offers 255 discrete levels. Pressure measurement resolution is differnet for each sensor pad. For example, a sensor with a saturation pressure (PSAT) of 200 PSI, will yield a pressure measurement resolution of 200 / 255 = .784 PSI / Digital Output. The vertical Pressure Legend (color bands) consists of thirteen colors; each of the thirteen colors represents all 255 levels of a sensel thus each color will have a range of values.

38. Sensor & Application Tips / Software Features cont. Sensor Turn-On Threshold – Tekscan software is factory default setting for noise threshold is 3 digital raw counts (out of 255). If a significant amount of random noise present, it is recommended to increase the lower limit (field) in the Pressure Color Legend. The noise is captured in the recording but will not be displayed; the Pressure Color Legend is a ‘visual filter’. The TARE function can remove any preload or pattern seen from the displayed image. Sensor Turn-ON Pressures Full RangePress Meas. ResolutionTurn-ON Pressure 5 PSI 0.02 PSI Depends upon sensel size 25 PSI 0.1 PSI 0.3 PSI 250 PSI 1 PSI 3 PSI 2,500 PSI 10 PSI 30 PSI

39. Sensor & Application Tips / Software Features cont. Shim Stock – Can minimize the effects of shear forces. A rubber block being loaded onto our mylar substrate sensor which in turn sits on a solid metal surface would tend to impart shear force and could damage the sensor in addition to yielding erroneous sensor data. Shim stock, such as Lexan (.005”.010”,.020”) Teflon paper, loose leaf paper or a thin piece of metal foil (stainless steel / beryllium copper), will offer more consistent sensor output. Calibrate with the same shim stock material as in the application. (Note: http://www.gelexan.com/gelexan/features.html) Another example is our sensor pad inserted between two metal plates; without any shim Stock such as a piece of paper, the sensor would most likely report more pressure peaks than if a piece of loose leaf paper was inserted in the interface. The piece of loose leaf paper would maintain the integrity of the pressure distribution pattern while filling in the ‘valleys’ thus ‘smoothing’ the ‘peaks’. Sensor Protective Cover – Most Tekscan sensors are constructed from two 0.001” mylar substrates and have a total thickness of ~ 0.004” +/- 0.0002”. Most sensors are also shipped with a 0.001” mylar protective layer which can add life to the sensor due to the extra protection it offers; it is recommended that the calibration includes the protective cover as well. Exception: Model 6220 / 6230 should have the protective mylar shipping cover removed for calibration and measurements. The cover has an adhesive and release agent on the sensor side; if a high load is applied, the cover may “set” in certain areas which can result in artifact load, that is load contributed by the cover itself. The added 0.001” thickness of this cover can cause the sensor to get caught inside the handle on the pogo pins; if pulled out, pogo pins will be damaged. Fold the cover back so it does not insert into the handle.

40. Sensor & Application Tips / Software Features cont. Saturating –If a sensor is loaded beyond its PSAT (labeled saturation pressure, which is a guideline since the material interface Tekscan tests with may be different than the customer’s material interface. The PSAT is a saturation pressure guideline. The best method to determine if the standard sensor PSAT is suitable for the application is to load the sensor in the actual application and set the vertical Color Pressure Legend to 0 to 255, which is full scale uncalibrated. The color image on the computer display should not be all blue in color nor al red or mostly red. There should be a mix of colors (some blues, greens, yellows, and maybe orange and brown).The average Digital Output should be ~ 220 which allows for pressure headroom for any pressure peaks. Reading from a sensor with a display of mostly red or all red does not leverage our thirteen colors in our Color Pressure Legend scale.The thirteen colors assist in resolving the pressure into different levels. If a sensor is pierced, cut, severely sheared, wrinkled, creased, or repeatedly bent in the same location, the sensor will exhibit an electrical open and / or electrical short or may simply report artifact pressure. A sensor should be inspected visually and after connected to the sensor handle to ensure no damage exists and that it is working properly. Pressing by hand or using a load frame to test if all sensels are reporting is common. A blank column or row may be corrected by reseating the sensor in the sensor handle.

41. Sensor & Application Tips / Software Features cont. Cutting Sensors – Some sensors lend themselves to being cut, that is some sensor designs allow for removing part of the sensor with an exacto knife, hole punch, or scissors resulting in no loss of data from the physical sensor region left after the cut. Sensor models 62220 / 6230 lend themselves to being trimmed from the inside outward in order to accommodate sliding the sensor over a bolt or part diameter. Model 5250 may be cut to be 5” x 10” based upon its electrical trace routing. Each sensor would be treated differently; sometimes it is easier to cut the sensor and insert the sensor into the handle and view the screen image when the sensor is loaded.

42. Sensor & Application Tips / Software Features cont. API (Application Programming Interface) – Tekscan offers a product, API 2 , which is a High Level interface and is outlined below: Requires Tekscan software version 5.X Writes equilibrated and calibrated data to a buffer for user program access API 2 is an add-on software module API 2 may be programmed with C++ Customer would write their own programming code using Tekscan’s library of commands API 2 is built into I-Scan’s top level (high level interface) API 2 is capable of exporting Real Time data LabView compatible (LabView has its own DLL (library) / user procedure) LabView can be written such that LabView “grabs” data from Tekscan sensor pad / software continuously by setting up a loop API 2 allows Tekscan’s software to send data to Client’s computer as well as allow Client’s software to “grab” data from Tekscan software Note: The DLL performs the job of communicating; transferring collected data from the Server (Tekscan) to the Client (customer) computer. The DLL may be loaded into the customer’s software to serve as a convenient bridge for graphing and transferring sensor data from Tekscan software to Client’s (customer’s) software The customer can modify Tekscan’s sample DLL (Fsx User) Microsoft Com is a protocol which may be implemented to transfer data from Server to Client via custom / commercial software Can be used with a RealTime window or a recording

43. Quick Start Check List Connect all Tekscan hardware to computer before starting-up computer Ensure all connections are secure Ensure proper sensor is selected for application Proper shape, size, spatial resolution, and full scale pressure range Test PSAT selection for proper range / best pressure measurement resolution Determine if a “shear protector / load transmitter” is required E.g. metal foil, teflon paper, piece of mylar, piece of loose leaf paper Start-up computer Launch Tekscan from Desktop / Windows Explorer If you receive handle not found error message, reboot or try downloading latest software driver from our website: www.tekscan.com Support. Call Tekscan at 800-248-3669 and ask for Technical Support or call Vince Carrara x 268. Ensure you know how sensor is physically orientated in the application e.g. determine sensor’s physical orientation with respect to the computer screen image Equilibrate if Tekscan equilibrator is available or if a custom produced one is available Calibrate while ensuring material interface, temperature, and timing are similar to the application . Save recordings. Post analysis.

44. Embedded Video Capture Minimum Required Hardware : DV (Digital Video) format camcorder with FireWire (iLink, or IEEE1394) port. Desktop computer: FireWire PCI card Notebook Computer: PCMCIA card with Firewire Firewire cable: Usually shipped with Firewire card Processor Speed: 600 MHz Intel Pentium III or AMD Athlon 600 Mhz Note: Sony’s newer proprietary Micro MV format is not supported. Required Windows Operating System : Windows 98 SE Win ME Windows 2000 Windows XP

45. Steps for Capturing Real Time Video and Synchronizing • Plug in FireWire to camera and computer FireWire Card • Turn ON camera • Aim camera at desired area for video capture • Open Real Time window • Select “Capture Video” button (camcorder with three lines in front of lens icon) on tool bar to open a Real Time video feed from camcorder lens • Check to see if “Movie Recording” button (sensor handle / camera icon)is selected • Select “Record” button (red diamond icon – Main Toolbar) which will record both the sensor data (.fsx file) and the Real Time video feed from the camcorder lens. • A playback window will automatically open when the recording has been manually stopped or the frame count has been reached • Select “Separate Movie / Video” button (two white sheets moving apart icon)

46. 10) Use play forward and play back buttons (video window) in order to determine by eye the best synch’d sensor image with video. • Select “Synchronize Video” button (two rectangular blocks moving in opposite directions icon) Note: Canon brand camcorders tend to slow the refresh rate on a Real Time Tekscan display. Note: You may playback the video either from the Main Toolbar or from the Video window. If you play from the Main Toolbar, then you need to stop from the Main Toolbar. The same for the Video window. Note: The playback speed from the Video window is fixed at 30 Hz. The playback speed from the Main Toolbar is adjustable under “Playback Speed” pull-down icon on the Main Toolbar.

47. Note: Playback Speeds Fast – ~ 1000Hz or less depending upon computer processor speed & # of sensels Midfast - ~ 33 Hz Normal - ~ 18 Hz Midslow - ~ 3 Hz Slowest - ~ .5 Hz Note: Right mouse click on the video window for playback options such as “Repeat Forever”, sound volume, etc.

48. Video Synch Tips Example: Motorcycle rider is a the test person say for a seat comfort and person with video camera is away from track (sidelines). The rider can stand on foot-pegs and then sit quickly onto the sensor. Repeat a few times. Then one can synch the video with the Tekscan recording. Example: F-Scan Mobile product. Subject can switch from left to right foot (marching in place) or better yet, jogging in place. This will allow a synch of the video and the Tekscan recording.

49. Video Capture with Four Camcorders – Description: Four camcorders could input (analog) separately to a Quad Processor and Switch unit; this unit would be processing in Real Time. The Quad Processor and Switch unit would send a single analog output signal to a Converter Box (analog  DV format). This converter would send out a continuous image from the camcorder lens as a single DV formatted signal to the computer. Tekscan software can accept a single DV formatted signal. A Firewire card as well as Tekscan software version 5.20 are required. A quad screen (four images) would appear on the computer screen.

50. Analog to DV converter –