Adopting ISCAN Tactical Pressure Sensor System in Ship Model Testing

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National Research Council Canada Institute for Ocean Technology Conseil national de recherches Canada Institut des technologies oc ´eaniques

SR-2009-25

Student Report

Adopting ISCAN Tactical Pressure Sensor System in Ship

Model Testing.

Lee, A.; Lau, M.

Lee, A.; Lau, M., 2009. Adopting ISCAN Tactical Pressure Sensor System in Ship Model Testing. St. John's, NL : NRC Institute for Ocean Technology. Student Report, SR-2009-25.

DOCUMENTATION PAGE

REPORT NUMBER

SR-2009-25

NRC REPORT NUMBER DATE

December 2009

REPORT SECURITY CLASSIFICATION

Unclassified

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TITLE

Adopting ISCAN Tactical Pressure Sensor System in Ship Model Testing AUTHOR(S)

Aaron Lee and Michael Lau

CORPORATE AUTHOR(S)/PERFORMING AGENCY(S)

National Research Council, Institute for Ocean Technology, St. John’s, NL

PUBLICATION

SPONSORING AGENCY(S)

IOT PROJECT NUMBER NRC FILE NUMBER

KEY WORDS

I-Scan, Pressure sensing

PAGES iv, 33 App. A-C FIGS. 19 TABLES 3 SUMMARY

The I-Scan system is a pressure sensing system manufactured by Tekscan. These sensors have been used in previous experiments similar to the one that is to be conducted at IOT. The National

Maritime Research Institute of Japan, Helsinki University of Technology and The Cold Regions Research and Engineering Laboratory have conducted the most notable experiments.

These sensors have some technical issues that arise in certain loading conditions. Some of these include hysteresis and drift. Furthermore, when actually using these sensors, methods must be devised for mounting, waterproofing and protecting them.

After reviewing of previous methods employed, procedures were developed for sensor mounting, waterproofing and protection. Double sided tape was used to mount the sensor and single sided tape was used to waterproof the sensor and protect. Testing was conducted and it is proved that double sided tape was a good way to mount and single sided tape was a very effective way to waterproof the sensor. As the method of protection, it could be improved but was still sufficient.

ADDRESS National Research Council

Institute for Ocean Technology Arctic Avenue, P. O. Box 12093 St. John's, NL A1B 3T5

National Research Council Conseil national de recherches Canada Canada

Institute for Ocean Institut des technologies Technology océaniques

Adopting ISCAN Tactical Pressure Sensor System in Ship Model

Testing

SR-2009-25

Aaron Lee and Michael Lau

December, 2009

SUMMARY

A tactile sensor is a thin film used to measure spatial distribution over a defined sensing area. The change in resistance, when a mechanical stress is applied, allow the force to be quantified. The I-Scan system is manufactured by Tekscan and is the most popular tactile sensing system on the market. There are four key components of this package. The data acquisition software that is installed on your computer and records your data. The MAP drive links the data software to your individual sensor model. The evolution handle is the hardware that connects the sensor to the computer via USB. The final component is the actual sensor.

IOT plans on using the I-Scan system to measure the ice pressure distribution on a model icebreaker. Similar experiments using the I-Scan system have been conducted by the National Maritime Research Institute of Japan (NMRI) and Helsinki University of Technology (HUT). Both of these experiments used different models with different numbers of sensors in different positions and the results were similar. These experiments showed that there is higher loading at the aft shoulder during turning and channel breakout tests.

Before a similar experiment can be replicated by IOT, procedures need to be developed to address certain technical issues. These issues include sensor mounting, waterproofing, and protection. After reviewing of previously techniques employed, it is decided that the best methods would be the use of double sided tape for mounting and single sided tape to waterproof and protect the sensor. These methods are applied to a friction board and tested. The mounting and waterproofing was very successful while the protection needs to be re-tested because the ice that was used was stronger than the ice that would be used for the actual model test.

TABLE OF CONTENTS Content Page SUMMARY... i LIST OF TABLES... iv TABLE OF FIGURES... iv 1.0 INTRODUCION... 1 2.0 LITERATURE REVIEW... 2 2.1 Previous Tests... 2

National Maritime Research Institute of Japan... 2

Helsinki University of Technology... 3

Cold Regions Research and Engineering Laboratory ... 4

2.2. Tactile Sensors... 5

2.3 The I-Scan System... 6

Data acquisition software... 6

MAP driver ... 7

Evolution handle ... 7

Sensor film ... 8

2.4 Additional I-Scan Equipment ... 9

Hardware... 9

Analysis software... 9

Trigger sync box ... 9

2.5 Alternate I-Scan Systems ... 10

High speed I-Scan ... 10

I-Scan lite ... 11 I-Scan handheld ... 11 2.6 Application of Sensor... 12 Requirements ... 12 Suggested methods... 12 Previous experiments ... 13

2.7 Waterproofing ... 14 Requirements ... 14 Suggested methods... 14 Previous experiments ... 15 2.8 Protection of Sensor ... 15 2.9 Calibration Methods ... 16 Requirements ... 16 Manufacturer suggested ... 16

National Maritime Research Institute of Japan... 17

Helsinki University of Technology... 18

Institute for Ocean Technology ... 19

2.10 Operation Issues... 19 Physical issues ... 19 Data acquisition ... 20 Errors... 20 Detaching Sensors... 21 3.0 SENSOR TESTING... 22 3.1 Overview... 22 3.2 Criterion ... 22 3.3 Materials ... 22 3.4 Procedures... 23 3.5 Technical issues ... 25 3.6 Testing... 25 3.3 Results... 27 4.0 CONDITIONING/EQUILIBRATING... 29 5.0 Conclusion... 30 APPENDICIES

Appendix A: Bibliography... A-1 Appendix B: Price Quote ... B-1 Appendix C: Spec Sheet ... C-1

LIST OF TABLES

Table 1: Rate of decreasing sampling rate with adding sensors [6] ... 8

Table 2: Compatible sensor model and specs for I-Scan high speed [6] ... 11

Table 3: Results from Flexural Strength test ... 28

TABLE OF FIGURES Figure 1: Two Sensor films applied to the model used by NMRI [1] ... 1

Figure 2: Positioning of eight sensors on hull used in NMRI experiment [1] ... 3

Figure 3: Ice contact in Straight going and Turning experiments [1]... 3

Figure 4: Sketch of tests conducted in TKK ice tank [3]... 4

Figure 5: Pressure-sensing panels installed on segmented indenter [4] ... 5

Figure 6: Wheatstone Bridge [5]... 6

Figure 7: Tekscan data software displaying 2D and 3D contour [6] ... 7

Figure 8: Tekscan’s Trigger Synch Box TS-100 [10] ... 10

Figure 9: PDA and sensor for I-Scan Handheld System [6] ... 12

Figure 10: Handle inside PLS cover [16] ... 14

Figure 11: Diagram of angles α and γ [8] ... 17

Figure 12: Calibration set-up for experiment [3] ... 18

Figure 13: Scenarios for ice contact with sensels [3] ... 19

Figure 14: Mounted sensor submerged in water... 26

Figure 15: Mock Ice Abrasion test... 27

Figure 16: Tape failure in abrasion test ... 28

Figure 17: Flexural Strength test... 28

LIST OF EQUATIONS Equation 1: Izumiyama's resistance force ratio ... 17

Adopting ISCAN Tactical Pressure Sensor System in Ship Model

Testing

1.0 INTRODUCION

IOT is preparing a series of model tests at its ice tank with the new Korean icebreaker ARION to assess its maneuvering performance. As part of the program, ice pressure distribution along the hull’s waterline is to be measured to provide local pressure data to assist in the development of a local pressure prediction mathematical model for ship maneuvering in level and pack ice.

At present, we are considering an off-the-shelf pressure measuring system, I-Scan, manufactured by Tekscan for the pressure measurement. Similar ship maneuvering experiments have been conducted by different organizations using this product. This was the main rationale behind IOT’s decision to use these sensors. Another important factor when deciding to use the I-scan system versus other pressure measuring devices was that the I-Scan sensor can be as thin as 0.1 mm so it can be applied to the model without significant model modifications (figure 1).

Figure 1: Two Sensor films applied to the model used by NMRI [1]

In the following report there will be a review of relevant literature related to the operation of the I-Scan system focusing on model tests in the marine environment. Background

information in preparation of the procurement of the pressure measurement equipment is given in Section 2. A set of specifications of equipment for procurement purpose is developed. Technical issues that have occurred in the past are in Section 2.10 along with their solutions with relation to its operation at IOT. Lastly, a breif discussion on the equipment commissioning and their results is given in Section 3.

2.0 LITERATURE REVIEW 2.1 Previous Tests

National Maritime Research Institute of Japan

The National Maritime Research Institute of Japan (NMRI) used the I-Scan system with an EVO sensor Model 5210N on this model in straight going and turning experiments [1]. The model was equipped with podded propulsors and set up in a free running mode. During the straight going tests the pods were positioned at a 0° angle. During the turning tests they would turn to a 20 or 30° and to make an “S” shape path. NMRI used eight sensors and positioned them differently for the straight going and turning experiments. For the straight going test the eight sensors were positions along one side of the hull [fig 2]. For the turning test, six sensors were placed at position number two and another four to eight sensors were placed on the side of the hull that was the outside of the turn. They required two I-SCAN systems installed on two computers to operate all eight sensors [1]. The method NMRI used for waterproofing the sensors was not discussed in their report. To adhere the sensors to the model NMRI used a double-sided sticky tape, MY-18 manufactured by Nichiban Co. Ltd. This is a very thin (0.1mm thick) but incredibly strong tape that is only available in Japan and surrounding area [2]. For IOT’s application we will need an adhesive tape that contains similar properties that can operate at a low temperature and is resistant to water and chemical corrosion. Once the experiment was complete, it was noticed that there was a larger difference in pressure distribution between the straight going and turning tests. In the straight going test it was noticed that there was dominant bow loading. During the turning tests this loading was more significant on the aft body on the outside of the turn. The difference in contact area between the ice and ship caused the loading change [fig 3]. Podded propulsors were used,

in this experiment and increase turning ability. If the conventional propeller and rudder were used the aft body load may not have been so significant [1].

Figure 2: Positioning of eight sensors on hull used in NMRI experiment [1]

Figure 3: Ice contact in Straight going and Turning experiments [1]

Helsinki University of Technology

Helsinki University of Technology (HUT) and The National Maritime Research Institute of Japan conducted an experiment to measure ice load distribution under different operational scenarios [3]. This experiment was conducted in the TKK ice tank and used two different models; a 15,700 dwt tanker and a 62,000 dwt cargo ship. The experiment consisted of straight going tests of multiple widths, channel break-out tests to port, and starboard and turning tests to port and starboard [fig 4]. The Teknillinen Korkeakoulu (TKK) tank is 40m by 40m, which allows for scale radii turning experiments. This was scaled from the standard turning radius of a Baltic Sea icebreaker. All the tests were completed with two different ice thicknesses, 20 and 25 mm scaled from 0.63 and 0.79 m respectively. These values were scaled from the standard thicknesses of ice in the Baltic Sea. 27 tests were completed in total. This includes 15 tests with the tanker and 12 tests with the cargo ship. To record the data, Tekscan’s 5210 I-Scan system was used to record the data. Four sensors were positioned on the port side of the hull at the bow, bow

shoulder, mid ship and aft shoulder. These sensors were attached using a thin tape. These experiments showed that there was dominant loading in the bow and mid ship section during the straight going tests. During the channel break out and turning tests loading was high on the aft shoulder. There was significant scatter in small load width. This was said to be typical with measured ice loads in full scale. With wider load widths this scatter decreased. A trend of decreasing load line as a function of increasing load width followed an exponential function. High loading was also exerted on the ice, it was noted that there was no bending and that crushing was the dominant failure [3].

Figure 4: Sketch of tests conducted in TKK ice tank [3]

Cold Regions Research and Engineering Laboratory

Cold Regions Research and Engineering Laboratory conducted a medium scale hydraulically driven indentation experiment to understand the crushing process of ice [4]. The experiment was conducted at the harbour in Lake Notoro, Hokkaido. They used a 1.5 m wide indentor to conduct two tests; the first used naturally and specially grown sea ice of various thicknesses and the second used strain gages frozen inside the ice to measure strains at different points. Both tests were run at speeds of 0.3, 3.0 and 30.0 mm s-1. The results for the first test were the only results reported. They installed four pressure-sensing panels on the face of a segmented indentor [fig 5]. These panels were attached to the indentor using an adhesive tape. The rate of frame acquisition for the sensor panels

were 1.25 Hz for 0.3 mm s-1, 12.5 Hz for 3.0 mm s-1, and 100 Hz for 30.0 mm s-1. A deflector plate above the indentor surface protected the wiring between the sensors and the computer. Their sensors were protected from water damage by encasing them in plastic sheets before installation onto the indentor. These sensors were not calibrated. Besides the sensor panels, data was acquired from load cells, displacement transducers, an accelerometer, and in inclinometer. These instruments gathered data at rates of 5 Hz, 50 Hz, and 200 Hz for the respective indentation speed. Before each test a surface was cut in the ice sheet parallel to the face of the indentor. The results for the high-speed tests (3.0 and 30.0 mm s-1) demonstrated a line-like trend for contact area. The data for the low speed test (0.3 mm s-1) showed a gradually increasing contact area because of creep deformation [4].

Figure 5: Pressure-sensing panels installed on segmented indenter [4]

2.2. Tactile Sensors

Tactile sensing is the detection and measurement of the spatial distribution of forces perpendicular to a predetermined sensing area. Research for tactile sensing is continuously growing. There are two different types of tactile sensors; kinesthetic sensing and cutaneous sensing [5]. Kinestheic sensing is used to detect internal forces while cutaneous sensing is used to detect external forces. The primary example of a cutaneous sensor is the human’s skin; this is the type of sensor that is developed by Tekscan. The

skin of a human would be hard to replicate in sensor form because a human hand has 17000 different mechanoreceptors. This type of sensor is highly resistance based. Piezoresistive pressure sensors are the oldest but most commonly used pressure sensors. This type of sensor is made of four resistors embedded in a micro-machined silicon diaphragm in a Wheatstone Bridge [fig 6]. This setup can accurately measure the electrical resistance. The electrical resistance of silicon changes under mechanical stress and will virtually never break. This means that when a pressure is applied, the diaphragm flexes causing a stress on the resistors. Crystalline silicon is embedded in the resistors; this produces a very stable sensor with a very rapid response time [5].

Figure 6: Wheatstone Bridge [5]

2.3 The I-Scan System Data acquisition software

The I-Scan data acquisition system runs off the operators PC and has many different visual features for viewing and storing data [6]. As this program collects data it can produce a 2D or 3D contour in real time [fig 7]. You can also adjust the pressure range of your sensor to change the sensitivity at certain pressures. This process is known as changing the sensor saturation. There is a procedure that should be followed when determining whether your sensor sensitivity is suited for your application. Using the raw data system, apply the load in compression on the sensor. Make sure the load is applied under the same conditions as in your experiment. The reading should give a value of

around 85 and the display should have a color mix of blue, yellow, orange and green. If this is not the case, adjust the saturation accordingly. Once the data is collected the software can create graphs of pressure, contact area or force vs. time, Frame count or X-Y position. It also has dynamic playback of two or more recordings side by side. The data can then be exported to such programs as Microsoft Word or Excel [6].

Figure 7: Tekscan data software displaying 2D and 3D contour [6]

MAP driver

A MAP driver is also required for the system to work properly with the software [7]. The MAP tells the Tekscan pressure display and analysis software how to read and display the sensor data. Multiple sensors of the same model only require one MAP driver but each I-Scan sensor model has a different MAP. Therefore the MAP included with the 5210N sensor would not work with a 5101 sensor [7].

Evolution handle

The handle is a very important piece of the I-Scan system [6]. This is the part that takes the data from the pressure sensor and passes it to the computer. The handle is a small item and measures 137.7 mm x 57.2 mm x 47.6 mm (LxWxH). It is connected to the computer by a 15 ft USB cable. This connection also powers the device so no batteries are required. The handle operates in a temperature range of -10°C to 55°C. It uses an 8-bit analog to digital converter for the possibility of a scanning rate up to 100 Hz [6].

Sensor film

The I-Scan 5210N Sensor is available in a variety of maximum pressure ranges, which include 82.74 kPa, 199.9 kPa, 1303 kPa and 6998 kPa [6]. The sensel matrix is 237.6 mm by 237.6 mm, containing 1936 sensels. These sensels are spaced out so there is 3.4 sensel per centimeter squared and have a maximum sampling rate of 100 Hz. The maximum scanning rate is only achieved with a limited number of sensors. The rate at which the sampling rate decreases is represented in table 1. These sensors have an operating temperature of -9°C to 60°C and are not waterproof. They are water resistant but if exposed to excessive amounts of water, they will leak through the side. This means that based on where the sensors will be used they must be waterproofed by the user [6]. If not calibrated to a certain set of units the sensors will produce raw values. A raw value is a number between 0 (no force) and 255 (max force) based on the force applied to the sensor [8].

Table 1: Rate of decreasing sampling rate with adding sensors [6]

There are many alternate choices of sensors besides the 5210N model [6]. In previous tests conducted by IOT, their sensor of choice was the 5051 model. This sensor comes in a much larger variety of standard pressure ranges. These ranges include 48.26 kPa, 137.9 kPa, 344.7 kPa, 517.1 kPa, 1034 kPa, 1723 kPa, 2413 kPa, 3447 kPa, 8273 kPa,

17236kpa, 34473 kPa a, 68947 kPa, and 172368 kPa. This is also a much smaller sensor then the 5210N model, having a sensing area of only 55.9 mm by 55.9 mm. This smaller area causes the sensor to have a much larger sensel density of 62 sensels per square centimeter. Other then its size and pressure range, all sensors have the same number of sensels and operate in the same matter with the same quality [6].

2.4 Additional I-Scan Equipment Hardware

There are a couple of add-ons to the I-Scan system that can be purchased that may make IOT’s experiment easier [6]. If it is decided that a computer will not be put on the model during the experiment, USB cables will need to be run from each handle to the computer. Tekscan sells an Active Repeater USB extension cable. These cables can be plugged unto each other until the required length is reached. This could be very difficult and confusing to configure but could be useful by avoiding a wet computer. Tekscan also sells another system called the I-Scan Cross-Handle Scanning System. The system, along with a VersaTek hub can allow you to plug up to eight sensors into one computer. This will reduce the required number of hardware connections while keeping all the features offered in the traditional I-Scan system [6].

Analysis software

Along with the things that come with an I-Scan system there are additional things that can be purchased to increase your data gathering capabilities [9]. There is a software add-on call Video Synchronization. This software add-on allows you to record and synchronize video files from your contact pressure data. The movie, the contact pressure pattern, and the pressure graph are all displayed through the Tekscan software at the same time. This can help you gain a further understanding of the data collection process. This software also links your video files and pressure files together allowing for an easier retrieval [9].

Trigger sync box

Tekscan’s Trigger Sync Box TS-100 [fig 8] has the main purpose of activating software to collect data [10]. This process works in three different ways. It can be used to trigger a

recording by hand. An external device such as an electric eye can be connected to the box to generate an input that will trigger the recording software. An external device could also be connected to receive output from the box for other data gathering purposes. The box works by generating a single pulse to a connected device once triggered. [10].

Figure 8: Tekscan’s Trigger Synch Box TS-100 [10]

2.5 Alternate I-Scan Systems High speed I-Scan

Other systems offered by Tekscan are the High Speed I-Scan System, the I-Scan Lite System and the I-Scan Handheld System [6]. The high-speed system is a robust system that can aid in data acquisition of fast applications. The high-speed system runs off the same software as the traditional I-Scan system so it will provide all the benefits that were included with the traditional I-Scan system. Some of these benefits include 2D and 3D pressure projection, data graphs, and exporting data to outside programs. The main difference with this system is it can run at scanning speeds of up to 20,000 Hz. This is 200x the scanning speed of a traditional I-Scan system. The sensors used with the high-speed system are patented thin sensors that can easily fit in place for most applications. These sensors have a five microsecond response time to ensure almost instantaneous data collection. Not as many sensors are compatible with the high-speed system as the traditional system. Sensor models that come standard with the high-speed system are the 9500 and the 9550. Other sensors that will work with the high-speed system are shown in

table 2. This system is very impressive but may not be necessary for such an experiment as ice impact. This type of system is normally used under such applications as air bag pressures. Such applications occur much faster then a model ship [6].

Table 2: Compatible sensor model and specs for I-Scan high speed [6]

I-Scan lite

The Lite system is another system that offers the same features as the traditional I-Scan system including pressure display, graphs and data exportation [11]. This system also offers a much faster setup time and is used for applications requiring known pressure patterns. Having a known pressure pattern will eliminate the need to repeatedly verify machine adjustments. This will remove the guesswork from machine setup. This system may not be beneficial for a model icebreaker test because it is unknown how or where the ice will act on the hull [11].

I-Scan handheld

The Handheld system is a great way to take pressure sensing outside the lab [12]. The software used in this system is a basic version of the software used in the I-Scan system. This system does not project a 3D pressure pattern. Instead, it just shows a 2D image. This system runs off a PDA so it can be taken anywhere [fig 9]. The PDA has one USB port for a sensor handle to plug into it. This is the main downfall of this system and the reason it cannot be used for an ice impact experiment. For this type of experiment

multiple sensors must be used to gather pressure data from all over the hull. One sensor would not be enough [12].

Figure 9: PDA and sensor for I-Scan Handheld System [6]

2.6 Application of Sensor Requirements

There are some basic requirements the tape has to meet. It should work effectively around -2°C, a typical operating temperature during tests. IOT uses a water-based solution of ethylene glycol aliphatic detergent and sugar (EGADS) for model ice production; hence, the tape must work in water and not be corrosive with the chemicals included in the mixture. It also must have a thickness comparable to that of MY-18, i.e., 0.3 millimetres. The I-SCAN sensors are re-useable and for ease of replacement due to sensor failure, it may be necessary to change the sensors during test that means the tape would have to be removable. It is important that every time when the tape is removed it does not leave a residue. Its strength must be maintained even though it can be removed.

Suggested methods

Tekscan offers some suggestions to apply the sensors [6]. The first suggestion is to secure the perimeter of the sensor with a cellophane tape. This method will do a good job of attaching the sensor but a lot of care must be taken when applying the tape. A cellophane tape will add thickness so it is very important that no tape contacts the sensing area. This would change the sensitivity of the sensor. It is also important that when covering the

perimeter of the sensor, the entire perimeter is covered and that there is no gap or overlap in the tape. The contact area of the sensor could be affected if gaps or over laps were present. The next method suggested by Tekscan is to use double-sided tape. This method had been used in previously discussed experiments. This tape would be applied to the model and then the sensor applied to the tape. This would give a very secure fit and would be easy to handle. It is important when applying the tape to the model that there are no gaps or overlaps between different pieces of tape. This change in thickness would directly impact the sensing surface. It should also be noted that the contact surface between the tape and sensor would be different from the model and sensor so sensors should be calibrated with the double-sided tape if this method is being used. The last method suggested by Tekscan is the use of adhesive spray. More specifically the 3M super 77 spray adhesive. This would be the easiest method to use because there is no worry about gaps or overlap to affect the sensing area. The spray can be applied directly to the model and the sensor is applied to the sprayed area. It may be wise to calibrate the sensor using the spray, like the double-sided tape it may change the properties of the contact area between the sensor and model [6].

Previous experiments

Information on how this problem was resolved in previous experiments is limited. Research has found that when NMRI conducted their experiment they used a simple double-sided sticky tape to apply the sensors to the model. They used the tape, MY-18, manufactured by Nichiban Co. Ltd. The tape was applied to the model and then the sensor was attached to the tape to produce a secure bond [15]. In a report on the experiment conducted by Helsinki University of Technology it was noted that the sensors were also attached to the model using the double sided tape tape. A figure shows tape on the outside of a sensor holding it in place. This would mean that the tape used was a single-sided tape, securing the sensor around its perimeter [3]. The Cold Regions Research and Engineering Laboratory did not mention their method of approach for attaching the sensors in their report for this experiment.

2.7 Waterproofing Requirements

The Tekscan sensors are not completely waterproof. To construct a sensor all the pressure sensing elements are contained within two very thin sheets of film. This means that it is possible for water to seep in through the connection between the two sheets. If water were to enter the sensor it would ruin the sensor. Whatever is used to waterproof the sensor will have the same exposure as what is holding the sensor in place. This means that the waterproofing method must allow the sensor to be resistant and operating in the same environments as the adhesive. As previously discussed, the sensor plugs into an electrical piece of equipment called the handle. Water could cause sever damage to a handle so it may also be important to protect it from water damage.

Suggested methods

It is important to waterproof the sensors because water damage will prevent them from working correctly. There are a couple of options when dealing with waterproofing. If we apply the sensor using the single sided cellophane tape, the tape can also waterproof the sensor. If applied carefully, sealing the entire perimeter will prevent water leakage. Tekscan recommended the use of plastic bags. A sensor could be placed in something similar to a zip-lock bag to be protected from all water contact. This would only work properly if the back was the correct size and the top of the bag was sealed correctly. To protect the handle, Tekscan also recommended the PLS Handle Cover [fig10]. This casing has spacing for cords and sensors to leave the casing and will protect from direct water contact [16].

Previous experiments

As with the information known about previous attaching methods, information known on waterproofing is limited. Nothing was mentioned in the report by NMRI about waterproofing. However, a figure within the report shows tape along the perimeter. This could have been used to waterproof the sensor if applied carefully to cover the entire perimeter of the sensor. Helsinki University of Technology did not mention anything about waterproofing either. They did attach the sensor by taping the perimeter of the sensor, this method could also be applied to waterproofing, applying the same methods used by NMRI. For the experiment conducted by the Cold Regions Research and Engineering Laboratory the sensors were placed in small, thin plastic bags to keep them protected from the water. These bags were then attached to the indentor to conduct the experiment.

2.8 Protection of Sensor

After the sensors are attached and waterproofed, shear forces become a concern. These sensors are meant to handle normal loading but can be damaged if exposed to excessive shear forces. Protecting these sensors is the next objective before the experiment can be conducted. In previous experiments, protection of the sensor or the method in which they were protected was not discussed. Through research, some methods have been devised but until tested there is no way of knowing if they will provide ample protection from the shear forces that will be exerted during the experiment. If using the adhesive spray to attach and waterproof the sensor as recommended by Tekscan, the thin layer of the film over the sensor may provide some protection as well. As mentioned above, the Cold Regions Research and Engineering Laboratory placed the sensors in bags to waterproof them. These bags could give some protection from shear forces. Tekscan also suggested the use of a thin polyethylene sheet over the surface of the sensor. This method would add the most thickness but should provide the most protection. Another method could involve the use of friction paint. Instead of painting the model and laying the sensors over the paint, apply the paint over the sensors. The layer of paint could provide the sensor with protection from shear forces.

2.9 Calibration Methods Requirements

The most important thing to consider when calibrating pressure sensors is the environment and its surrounding conditions. In the case of IOT’s experiment, measuring ice load distrobution on a model hull the experiment conditions should be replicated as best as possible for the calibration. The sensor is being attached to a model hull for the experiment so for the calibration it should be mounted on a similar material with similar properties. The main thing that will be exerting force on the sensor during the experiment will be ice. This means that ice should be used to apply the force on the sensor during calibration. Lastly, the experiment will be conducted in a cold room at -2°C therefore the calibrations should take place at a similar room temperature. Matching all these characteristics will provide more accurate data.

Manufacturer suggested

Before a sensor is used it is very important that certain procedures are taken to ensure accurate and consistent results. All sensors must be conditioned, calibrated and equilibrated [13]. After calibrating your sensor for the experiment it will have an absolute accuracy of ±10% and after conditioning your sensor this error can be lowered to ±2-5%. Conditioning is a simple procedure, which involves loading the sensor slightly over the range you will be using. Do this multiple times to allow the sensor to become used to be loaded. Conditioning a sensor before an experiment is equivalent to stretching before exercise. Equilibration and calibration are similar processes. For static loading you calibrate your sensor by equilibrating it, applying a constant load over the entire sensor to make sure that the outputs are all the same. Tekscan manufactures a wide variety of equilibration devices. These methods cannot be applied to dynamic loading. Equilibration is still an important process whether your test is static or dynamic loading. Equilibration will make your sensor last longer and improve its functionality. If sensors begin to develop dead spots, equilibrating will correct these flaws. A sensor must be calibrated under the same conditions that it will be tested in. This means that it should be calibrated in a similar surrounding atmosphere with a material that has similar mechanical properties as what will be used in the experiment. The process of calibrating a sensor

involves adjusting the sensors output according to the force applied in different applications [13].

National Maritime Research Institute of Japan

Izumiyama designed another way of calibration in 2005 [8]. He conducted a series of resistance tests on a ship in ice using the I-scan system. He compared the data from the resistance tests with the average raw data received from the sensors. From here he created a ratio CR, that involved FR, the resistance component of the force and FN, the normal component of the force. This produced equation 1.

CR = FR / FN = sinαcosγ + μcosα

Equation 1: Izumiyama's resistance force ratio

In this equation α and γ are the waterline and normal frame angles and μ is the coefficient of ice-hull friction [fig 10]. DR, the raw value corresponding to the resistance can then be calculated using equation 2.

DR = ΣCRiRi

Equation 2: Raw resistance

The correlation between resistance and DR can then be shown on a plot of resistance vs. DR [8].

Helsinki University of Technology

Another method of calibration was used in an experiment conducted by Ship Laboratory in the Helsinki University of Technology [3]. This experiment was also very similar to the previously discussed experiments as well to the one IOT would like to conduct. The university attached a sensor to a plate and mounted it in ice. They used an indentor attached to a load cell that would apply a force to the plate. The plate would then push the sensor into the ice [fig 10]. A calibration curve was then generated based on the data received from the sensor and the force in the load cell. The main problem with this method was caused by the structure of the ice was used. The ice causes a very thin but very strong layer on top of the ice. This layer will absorb most of the force. It also must be noted that there are very small gaps between each sensel on the sensor. Therefore, depending on where the sensor is positioned, the thin layer could contact the gap between sensels or in the exact middle of a sensel [fig 11]. This would cause almost no load or a very high load, respectively. Another problem they encountered was when the sensor was giving readings before a force was applied. This was mostly caused by noise in the data. This noise was created by the stress in the sensing sheet that was caused by the sticky tape used to apply the sensor. In this case the noise was consistent so could be calibrated [3].

Figure 13: Scenarios for ice contact with sensels [3]

Institute for Ocean Technology

IOT has had some experience working with the I-Scan system [15]. This experience includes some calibration work. Their approach to calibrating the sensors was simpler compared to other methods but involved a lot of trial and error. The main idea was to use a hydraulic press to apply known loads over different parts of the sensor. This took different trials because the force had to be applied in a way that would not ruin the sensor. It was noted that each new area of applied force had to be fully contained within the sensing area. If force were applied outside the sensing area it would change how the force was applied to the sensor. They also chose to cushion the force with layers of pressed industrial paper towel. This worked because it eliminated hard edges and would not extrude. This protected the sensor from both ripping and cutting [15].

2.10 Operation Issues Physical issues

Possible complications can occur while preparing these sensors [15]. It is important to remember that these sensors are disposable and may break after multiple tests. A sensor is very delicate and must always be handled with care. When first removing the plastic layer from the sensor it is best to do so slowly to prevent damage to the sensor. Touching the area where the handle retrieves data could ruin the contact between the sensor and the handle so it is important to only hold the sensor from certain locations. When preparing to use the sensor, the sensor must be cleaned gently with a damp tissue. This must also be done for any surfaces that will contact the sensor. This step will remove any dust particles from under a sensor. It is possible for small particles to puncture a sensor when pressure

is applied. This is also true for air that might be trapped under the sensor so all air must be removed. When applying a force to a sensor it is important to only apply the force on a flat surface. If the force is hanging over an edge it will cut the sensor in two. When applying a force within the sensing area of a sensor the force should be cushioned. If not it is possible for the edge of whatever is applying the force to cut the sensor. Care must also be taken when cushioning the force. If a piece of foam is used, when force is applied to the foam it will extrude. The sensor will not extrude, however certain sensels may be ruined or the sensor may rip with the expanding foam [15].

Data acquisition

As already discussed, these sensors are capable of data acquisition of speeds up to 100Hz [15]. This is true for constant loading and when the applied force is changing at a relatively slow rate. When strong loads are applied or change quickly this system is not as accurate. For example, if you were to instantly apply and hold a load 100N onto a sensor the graph should be composed of all straight lines. The graph produced by the I-Scan system will generate a curved line gradually increasing to 100N. These graphs are totally different and represent two different events. If the load was instantly applied and then removed, I-Scan will generate a graph that may not even reach 100N. This could cause large errors if the purpose of the experiment is to determine the force applied [15].

Errors

These sensors are very accurate equipment especially when dealing with static loading. The sensors are not perfect however and a couple of issues arise after continued loading [13]. The two main problems involved in static loading are repeatability and drift. Repeatability is the difference in the output values after applying the same load multiple times. Drift is the change in the output value while a constant load is applied. The user manual says that these issues should be negligible at first but may increase after multiple testing. When dealing with dynamic loading the problem of hysteresis arises. Hysteresis is the difference between two different output signals taken at exactly the same pressure but taken during a sequence of increasing or decreasing pressure. The value of hysteresis during increasing pressure has been tested to be small while the value increases slightly

during decreasing pressure [13]. Tekscan does not provide data to compensate for these errors but Queen’s University and the Orthopedic Biomechanics Laboratory completed an experiment to test the accuracy of these sensors in static loading. In their report it was noted that the test were completed in a way to minimize these errors, unfortunately this method was not disclosed. The tests consisted of 35 trails, which resulted in an error of the absolute measured force being 6.5% with a standard deviation of 4.4% [14]. Another factor that must be discussed is an error when applying a sensor to a curved surface. Placing a sensor on a curved surface causes a preload on the sensor. This preload affects the pressure readings and measured contact area. The radius of the curvature and the pressure range of the sensor determine the magnitude of preload. Lower pressure range sensors are more sensitive and will suffer from a greater preload. To account for this preload it is important to calibrate the sensors on a matching curvature as used in the experiment [6].

Detaching Sensors

It is very important for the sensors to be removable from the model after they are applied [15]. Even though this is important, it is even more important that the sensors do not come off before anyone wants them too. This is a concern because there are multiple possibilities for this event to occur. It is possible for the sensors to be torn off the model before the experiment even begins. Before the model is placed in the water the sensors must be applied then the model is placed in a set of slings and lowered into the water. The main concern is the slings ripping off the sensors because they will be placed directly over them. This threat cannot be completely eliminated but can be reduced by designing a protective jacket. Another option is to modify the model so it can be lifted by another method besides the slings. It is also possible for the ice to tear off the sensor during the experiment. This could happen if a string of ice hooked in or got underneath a sensor. This event can be reduced by careful selection and application of what is applied. It is important when choosing materials that they are as thin as possible. Adding bulk to the model will create edges for the ice to catch on. If applying tape, there cannot be any gaps or overlap. If there are gaps there is an increased risk of ice going in that gap and if there is overlap it will create uneven surfaces. The larger edge provides more surface area for

the ice to hit. The more ice hitting an edge will create a larger shear force, which will weaken the sensor hold, which will increasing the chance of it ripping off [15].

3.0 SENSOR TESTING 3.1 Overview

The purpose of testing was to take the ideas learned from other tests, design a procedure to apply these methods and actually apply the methods to make sure they work. A proposal was written to identify what problems needed to be solved and possible solutions for them. These problems were the methods of mounting and waterproofing of the sensors. Within the proposal there was a discussion of the previous experiments, a brief discussion of the methodology used by other tanks, a step-by-step procedure of the methods we would like to test and some technical issues with these methods. Running tests on the methods used will help decide if the method is best for our experiment.

3.2 Criterion

Before testing the different methods we had to be clear on what we wanted the most appropriate method to accomplish. For a method to be deemed acceptable for an experiment it had to be firmly held in place, the edges of the sensor had to be water tight, there can not be any wrinkles or air bubbles in the sensor, the sensor should be able to withstand shear stress from ice, there should be substantial abrasion resistance, and there should be the least added thickness as possible.

3.3 Materials

There were only a couple of required materials for the actual testing, waterproofing and protecting of the sensor. The first, and most important was the sensor itself. Tekscan generously gave us some defective sensors so we could properly test the sensors with out ruining good sensors. Double sided tape was also used. It took some time and research to find applicable tape and someone that distributed it. Our final decision was with the 454-AC double faced polyester tape from Can-Do tape. This is a half mil thick tape that has a high tack and shear strength. For the single sided tape we used a 3M 471 waterproof tape. This tape was used to seal the edges of the sensor. The last main material was the board

that the sensor was mounted on. We used a ¾ inch piece of plywood. The face of the wood where the sensor was applied was coated in 0.05 friction paint. This was to replicate the model ship surface.

3.4 Procedures

The following are the detailed instructions as they are outlined in the proposal. These are step by step lists for each procedure so all important details are covered.

Surface Preparation:

This is a description of the procedure that should be complete first. I describe how to properly clean the surfaces being used to avoid damaged equipment.

- Clean model surface

o Using a damp cloth wipe down the mounting surface where the sensor will be applied to remove it of any particles that may damage it.

- Clean the sensor surface that will be applied to the model

o Using the same cloth wipe the sensor surface that will be applied to the model to remove it of any particles that may damage the sensor

- Depending on method of application place the sensor on the damp model surface o If the method of application does not involve applying something under

the sensor, lay the sensor on the surface. The moisture will create a weak bond.

- Remove the air bubbles from under the sensor

o With the cloth, gently rub the surface of the sensor to remove air bubbles trapped underneath.

Double-Sided tape:

It lists the detailed procedure on how to properly handle and apply the tape. Depending on the distributor, it may be possible to get custom fit tape so only one piece of tape will be necessary per sensor.

- Do no complete the second part of Surface Preparation

o This procedure involves putting something behind the sensor so it should not be put on the surface before the tape

o One by one place vertical strips next to each other along the length of the model

- Lay tape to cover area of sensor

o Sensor area should be fully covered by the tape on the model. It is very important that there are no gaps or overlaps between pieces of tap. This will directly influence the sensing area.

- Apply the sensor to the tape

o Match one corner of the sensor to its matching corner of tape o Gently press down the sensor along its diagonal

o Finish by pressing the remaining sensing area onto the tape.

o Depending on the surface curvature it may be impossible to mount a sensor without air bubbles or wrinkles.

Single Sided Tape:

This will be our main protection from water and edge damage. It should provide sufficient hold to stop water from leaking in through the edges. It will also create a transition from the model surface to the sensor surface to eliminate damage to the sensor edge. The following is a detailed description of how the tape should be handled and applied.

- Select mounting method

o It is possible that single sided tape will not provide the required hold for the experiment so another method should also be used

- Cut four pieces of tape

o You will need four pieces to cover the whole perimeter of the sensor o Two pieces will be longer and two pieces will be shorter

- Place the four pieces of tape around the perimeter of the sensor o Place the two longer pieces along the vertical edges

o Place the shorter pieces between the two longer pieces, along the horizontal edges.

o There should not be any gaps or overlaps at the corners of the sensor. Leaving gaps or overlaps could affect how the sensor is impacted

3.5 Technical issues

None of these procedures are well practiced so there is a possibility for errors to occur during the steps of some procedures. There are some issues that are expected to occur during multiple application procedures. Applying the film to a curved surface will make it difficult for the film to rest perfectly flat on the surface. This could create wrinkles in the film or air bubbles under the film. A wrinkle in the sensor would cause an automatic preload and may fold when a force is applied. If an air bubble is trapped under the sensor the data that is recorded when it is loaded will be affected.

There are also more specific issues that arise when dealing with tape. How tape is positioned will influence the problem that may arise. This will only occur if there are gaps or overlaps between the different pieces of tape directly affecting the way the sensor is loaded.

3.6 Testing

This main combination of methods will be tested thoroughly to see if it has substantial shear resistance, abrasion resistance, and edge strength. Defective sensors will be mounted on a friction board for testing. Once the sensor is mounted and the single sided tape is applied around the edges on the friction bored an ice friction test will be conducted. This involves sliding a piece of ice across the surface of the sensor and observing if it holds its position or is damaged in any way. This test will be deemed successful if the film does not slide on the surface, get peeled off the surface or become punctured. If this test is successful, the watertight seal will be tested. The mounted sensor will be submerged in water and left for a certain amount of time. After this time period if water has still not broken the seal it will be an acceptable method. For the actual testing of the materials and methodology, the procedures above were followed very closely. Three pieces of double-sided tape were required to cover the entire surface of the sensor. These pieces were applied first. The two outside pieces had to be modified to match the shape of the sensor. Once the sensor was cleaned it had to be applied to the double-sided

tape. This was probably the most difficult part of the entire process because once the sensor came in contact with the tape it would be very difficult to remove. With the help of another person we placed the sensor perfectly in place with no air bubbles. The next step was to apply the single sided tape. The sensor is not a perfect square so required five pieces of tape versus the originally expected four. The corners of some pieces had to be cut to match up with other pieces. Once this was complete the board was submerged in water. The water reached half way up the sensor [fig 14]. The sensor was left in water over night to ensure the seal would last. Once the waterproofing tests were complete, the ice abrasion tests were conducted. Facilities made some ice and cut it to a manageable size. The ice would be slid across the surface of both the single and double sided tape. The sensor was not involved in this test because it was not necessary. The ice would be continually slid back and forth until the tape failed. A mock abrasion test with the senor is shown in figure 15. Once the abrasion test was complete, the flexural strength of the ice was measured. Mounting it on one side and applying a force to the other side, similar to a cantilever beam achieved this. The force steadily increased until the ice fail. All dimensions would be recorded using a micrometer and the results recorded using a strain gauge. The last test was to check the removability of the tapes. This was done by simply applying tape to the friction board, allowing it to set and removing it.

Figure 15: Mock Ice Abrasion test

3.3 Results

The board was left submerged in water overnight. The next morning the board was removed from the bucket and of excess water on the surface. The sensor was first visually inspected to see if any water could be found between the two layers of the sensor. When no obvious signs of water damage could be found the sensor was physically inspected by hand. Once this was complete there was no water found. This proves that waterproofing the sensor using single sided tape was very successful. The abrasion test was not as successful. The test was conducted twice with two different pieces of single and double-sided tape. For the first test, a constant force was applied as the ice moved back and forth. The double-sided tape failed first after 14 slides followed by the single sided tape after 31 slides. For the second test only the weight of the ice was pushing down. Again, the double-sided tape was the first to fail after 63 slides followed by the single sided tape after 120 slides. In both tests the first failure came shortly after the ice began to break apart. This is demonstrated in figure 16. The flexural strength test was conducted on four different pieces of ice. The results are shown in table 3. This test is shown in figure 17. The last thing that was tested was the removability of the tape. Once the tape was removed there was no residue left behind, resulting in another successful test. This is important incase sensors are damaged during testing; they can be replaced without a huge mess.

Figure 16: Tape failure in abrasion test

Table 3: Results from Flexural Strength test

Ice Block Thickness (cm) Width (cm) Overhang (cm) Load (lbs) Load (N) σf (Kpa)

1 4.02 8.25 7.51 0.84375 3.753185625 27.8829732

2 3.76 7 6.82 1.375 6.1163025 28.9440923

3 3.75 7.91 5.86 Too High N/A N/A

4 3.75 6.84 6.35 0.53125 2.363116875 27.0933333

5.0 CONDITIONING/EQUILIBRATING

As stated above, conditioning a sensor is preparing it to be used by getting it used to being loaded. Equilibrating it is to apply an even load across the entire sensor and to adjust the sensels according to that even load. This process has yet to be applied to the sensors to be used in the icebreaker experiment but has been applied to a larger sensor to be used in an Oceanic project.

The sensor was placed in the hydraulic press and layered with a blanket, Styrofoam, and plywood [fig 18]. This would help create an even load and protect the sensor from any damage. Once everything was centered the press was lowered. Before loading began the maximum force of the sensor was calculated so this force would not be exceeded or reached. The press loaded the sensor to ¾ of it maximum force. The sensor demonstrated very unbalanced loading. Parts of the sensor showed loading while other parts showed none. The press was then set into a sinusoidal load pattern [fig 19]. This pattern continued for thirty minutes and the sensor began to even out load wise. Everything was then removed from the hydraulic press and the entire process was repeated.

Figure 19: Hydraulic press pattern

4.0 Conclusion

The I-Scan sensor system is a very popular set of equipment. It has been used in many previous applications and experiments. The sensors themselves have some issues that can be resolved through proper planning and configuration. These sensors have been used in very similar experiments to the one that is to be conducted at IOT. Past experience of the use of these sensors in this field makes them the perfect candidate for the IOT experiment.

The main goal of the experiment at IOT is to replicate these past experiments, by taking their methods and applying them here while also making adjustments and improvements to the methodology. The main issues that have been described along with solutions have been the mounting, waterproofing and edge protection of these sensors. After analysis and discussion of different methods it was decided that double sided tape would be the best method for mounting with the combination of single sided tape to waterproof and protect the sensor. After sometime looking for the most appropriate tape testing could begin.

The testing process was conducted in three main stages, the mounting, testing waterproof and testing abrasion. The mounting proved the double-sided tape offered a very strong

hold. After leaving the sensor submerged in water over night, it was successfully waterproofed. Ice abrasion tests could have been more successful but were tested against stronger ice then they would see in a natural environment.

Overall the testing results were positive which proves that these methods are good candidates to be used in a full-scale experiment.

REFERENCES

[1] Izumiyama K., Wako D., Shimoda H., and Uto S., (2005), “Ice Load Measurement on a Model Ship Hull”, Proc. 18th Intl. Conf. on Port and Ocean Engineering under Arctic Conditions, Vol. 2, pp. 635-646, Murmansk, Russia [2] Nichiban Homepage. Nichiban Co. www.nichiban.co.jp/

[3] Valkonen, J., Izumiyama, K. and Kujala, P. (2007). Measuring of Ice Induced Pressures and Loads on Ships in Model Scale, The Proceedings of the 10th International Symposium on Practical Design of Ships and Other Floating Structures, Houston, Texas, October 1st - 5th, 2007, 1206-1213.

[4] Sodhi D.S., Takeuchi T., Nakazawa N., Akagawa S., and Saeki H, (1998), “Medium-scale Indentation Tests on Sea ice at Various Speeds”, Cold Regions Science and Technology, pp. 161-182

[5] Billimoria S., Mukherjee N, Petrovskaya A, Khatib O. “Tactile Sensors”. Project report. Stanford University. 2008

[6] Tekscan Homepage. Tekscan Inc., www.tekscan.com

[7] Tekscan Industrial Catalog. Tekscan Inc.,

http://www.tekscan.com/pdfs/Industrial-Catalog-Introduction.pdf

[8] Matsuzawa, T., Wako, D. and Izumiyama, K., (2006), “Local Ice Load on a Ship with Podded Propulsors”, Proceedings oh the 18th IAHR International

Symposium on Ice. Ohio, U.S.A Vol. 2, pp. 33-40 [9] Tekscan’s Video Synchronization Catalog, Tekscan Inc,

http://www.tekscan.com/pdfs/I-ScanVideoSynch.pdf

[10] Tekscan’s Trigger Box flyer, Tekscan Inc,

http://www.bioland.com.tw/documents/tekscan/Trigger%20Synch%20Box%20Fl yer.pdf

[11] Tekscan’s I-Scan Lite System Tekscan Inc,

http://www.tekscan.com/industrial/iscanlite-system.html

[12] Tekscan’s I-Scan Handheld System, Tekscan Inc,

http://www.tekscan.com/industrial/iscan-handheld-specs.html

[13] Tekscan I-Scan User Manual., Tekscan Inc,

[14] Wilson D., Eichler M. and Hayes W. (2000), “Accuracy of the Iscan Pressure Measurement System” Paper presented at the RTO HFM Specialists' Meeting on

"Soldier Mobility: Innovations in Load Carriage System. Design and Evaluation ", held in Kingston, Canada, 27-29 June 2000, and published in RTO AIP-056. [15] Bugden, A., Personal Communication

Appendix A: Bibliography

1. Ice Load Measurement on a Model Ship Hull by Koh Izumiyama, Daisuke Wako, Haruhito Shimoda, Shotaro Uto

This report talks about an experiment conducted by NMRI. The experiment involved measuring ice pressure acting on a model hull using the I-Scan system. This model used podded propusors in straight going and turning tests.

2. Measuring of Ice Induced Pressures and Loads on Ships in Model Scale by Janne Valkonen, Koh Izumiyama, Pentti Kujala

This report talks about an experiment conducted in the TKK ice tank. The purpose was the measure ice pressure distribution patterns along a model hull. Multiple variations of straight going, turning and breaking out tests were completed with a tanker and cargo carrier model.

3. Medium-scale Indentation Tests on Sea ice at Various Speeds by Devinder S. Sodhi, Takahiro Takeuchi, Naoki Nakazawa, Satoshi Akagawa, Hiroshi Saeki This report discusses a medium scale indentation test on sea ice in the Harbor of Lake Notoro. Using a hydraulic press they pushed a segmented indentor into the parallel face of a floating ice sheet. From the data collected from this experiment the fracture

toughness of the ice could be estimated.

4. Tactile Sensors by Sherri Billimoria, Nandini Mukherjee, Anna Petrovskaya, Oussama Khatib

This report talks about the many different for the wide variety of pressure sensing technology. It discusses how pressure panels work, how the have evolved, and the two main types of pressure sensing

5. Local Ice Load on a Ship with Podded Propulsors by Matsuzawa, T., Wako, D. and Izumiyama, K

This report discusses a free running model experiment conducted at NMRI. The purpose of this experiment was the measure the local ice loads on a model ship with podded propulsors. The experiment was conducted both in straight going and turning tests.

6. Accuracy of the Iscan Pressure Measurement System by David R.Wilson, Mark J. Eichler and Wilson C. Hayes

This report talks about an experiment conducted by the Orthopedic Biomechanics Laboratory to test the accuracy of the I-Scan pressure system. These tests were done for static loading by applying a known load using a custom built indentor. Thirty-five trials were conducted and it was established that the I-Scan sensor was more accurate then a Fuji Film sensor.

Appendix B:

Price quote for Tekscan’s I-Scan system Hoskin Scientific

Equipment Proposal #

BQ0814378

Tekscan I-Scan

Pressure Measurement System

for

Ice Load Application

Aug 17, 2009

Prepared for:

Austin Bugden

National Research Council Canada

Kerwin Place & Arctic Avenue

P.O. Box 12093

Institute for Ocean Technology

St. John's, NL A1B 3T5

Prepared by:

Hoskin Scientific Limited

4210 Morris Drive Burlington ON L7L 5L6

Tel: 905-333-5510 Fax: 905-333-4976

Tekscan Equipment Proposal

I-Scan Pressure Measurement System with Adjustable Gain

Thank you for the opportunity to quote a Tekscan Pressure Measurement System. The I-Scan system supports real-time visualization of pressure distribution patterns and recording of snapshots and movies, which can be viewed and analyzed in I-Scan or exported to other software products. Adjustable Gain allows the user to raise or lower the full pressure range of the sensor by up to a factor of at least three, and more in many cases. The system is small, light and rugged, giving this system excellent portability for field studies. I-Scan includes the following components:

Hardware:

(1) Evolution USB Connected Data Acquisition Handle with ~15’ cable

Software:

(1) Adjustable Gain Pressure Measurement Data Acquisition Software, including: • Dynamic Movie Recordings up to 100 Hz sensor scanning rate for up to 2288

elements

• 2-D, 2-D contour, 3-D wire frame, 3-D Solid and 3-D reversed Image Displays • Selectable Pressure Display Ranges and Units of Measure

• Comments accompany recorded data to document experimental conditions • Graphs of Pressure, Contact Area or Force vs. Time, Frame count or X-Y

location

• Smoothing or averaging Algorithms to reduce spurious influences

• Tare function removes pre-load data from sensor, and toggles to gross load • Dynamic Playback of 2 or more recordings side-by-side

• Movie editing to remove uninteresting frames, cut spurious data, or selectively average data

• Copy and paste data transfer to other Windows applications such as Word or Excel

• ASCII File Pressure Output for Single Frame, Multi-Frame or Graphs

Sensor MAP Drivers:

Sensor MAP display software for TWO sensor types is included:

The sensor MAP is the license to use a particular sensor pattern on your system. Additional Sensor MAP’s are available for $4,120 CDN each

NOTE: Sensors and Electronics are not waterproof.

Sensors and Standard Saturation Pressures:

Some Recommended Sensors for This Application are Below: Select One

These sensors are Ultra-thin (.004”, 0.10mm) flexible printed circuits with polyester substrate.

Check out www.tekscan.com for the complete industrial sensor catalog.

NOTE: SoftWare Adjustable Gain allows for fine tuning of pressure sensitivity range +/- X 4.

Sensor Active Area Resolution Row x Col Std. Pressure

5051 2.2 X 2.2” 56 x 56 mm .05 x .05” 1.27 mm 44 x 44 1936 Sensel 7, 20, 50, 75, 150, 350, 500, 1,200 2,500, 5,000, 10,000 & 25,000 $160 CDN Ea 5210N 9.45” (238 mm) square 0..213” (5.41 mm) 44 x 44 1936 Sensel 12, 29,189, 1015 $365 CDN Ea 5 Sensors with total value up to $1,500 CDN are included with system. (Please specify

Sensor Number and Pressure.Range) *Additional sensors may be purchased at above prices.

(1) Sensor carrying case (1) System carrying case

System Manual:

(1) Instruction manual including troubleshooting guide.

On-Site Installation / Training:

Onsite installation & training Class: In your facilities, on your application by Tekscan Rep.

Support:

(90) Day software and technical support provided by telephone, email and website FAQ’s.

(1) Year hardware warranty

*Optional extended support contracts and warranties available.

I-Scan System - Base Price $29,350.00

Suggested Minimum Computer Requirements Furnished by Customer

• Intel Pentium 800 Mhz or higher processor1

• 512 MB System RAM

• 1 GB hard drive • CD ROM drive

• Windows 2000 (SP4), XP (SP2), or Vista operating system (32-bit versions only) • USB Port

Terms

Freight and Taxes: FOB Burlington, taxes extra

Delivery Terms: 2-4 weeks after receipt of order

Payment Terms: Net 30 days

Pricing: All prices quoted in CDN Dollars

Pricing Summary

I-Scan EVO System - Base Price $ 29,350.00

(4) Sensor 5210N - FREE $ No Charge

Shipping (from Burlington ON to St. John’s NL) $ No Charge

TOTAL $ 29,350.00

Optional Items:

(7) EVO Data Handles @ $5750 ea $ 40,250.00

(12) Sensor 5210N $365 ea $ 4,380.00

Video Synchronization Software $ 2,340.00

External Trigger Synch Box $ 1,170.00 $

CDN TOTAL with Options $ 77,490.00

Optional Items

Additional Sensor Maps:

$4,120.00 ea

The sensor Map is the license to use a particular sensor pattern on your system.

Additional EVO Data Handle for Multi Handle System

$5,750.00 ea

Allows for reading multiple sensors simultaneously. Includes a powered USB Hub for two or more Handles

Extended Tech Support / Software Maintenance Plan $1,500.00/yr

Toll free customer support for one year. Includes all major software updates. Email notification of new updates for software and drivers, new maps and products.

API- 2 Real Time Data Output $5,750.00

Writes arrays of data to buffer or DLL to be used by other applications while I-Scan is running.