SURVICE Engineering

Metrology Vector Bar Team SURVICE Phase 4

Andrea Liem Mike Morton Kristen Domboski Raymond McCauley

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Table of Contents

Abstract ....………………………………………………………………………………………3

Background …………………………………………………………………………………….3

Design Process .…………………………………………………………………………..........4

Subsystems ………………….................................................................................6

Testing and Analysis ……………………………………………………...............................8

Test Recommendations ………………………………………………………………..........10

Cost Analysis ……………………………………………………………………...................11

Path Forward ………………………………………………………………………………....12

Conclusion …………………………………………………………………………………....12

Appendices

Appendix A: SolidWork design photos …………………………………………….14

Appendix B: Final design photos ...…………………………………………………16

Appendix C: Cost chart ………………………………………………………………18

Appendix D: Subsystems ….………………………………………………………...19

Appendix E: Concept selection .…………………………………………………….19

Appendix F: Ergonomic handle iterations………………………………………….21

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Abstract SURVICE Metrology is in what they refer to as a “pre-Phase 2” mode. This phase

two is a timeline for SURVICE Metrology to provide NAVAIR with the models and prototypes of innovative and advanced technology according to NAVAIR’s needs. NAVAIR is getting ready to launch their next-generation Joint Stike Fighter aircrafts. Most of the next-generation fighters have been incorporating more composite structures into their manufacturing department. Composites are new to the industrial world and are still being constantly studied, created, and improved. SURVICE Metrology is providing NAVAIR with a unique piece of technology they call their “iGPS laser-based metrology system vector bar” or “vector metrology bar”. This device provides 3-D modeling of defects of the composite structure of the aircrafts. Their current vector metrology bar is a basis for their new and more improved equipment.

In an effort to move towards production and sales, SURVICE Metrology is looking for an ergonomic and advanced-technological vector bar. The main purpose of this project is to improve their set-up and equipment they use for their iGPS metrology vector bar. The system needs to be improved by automatically recognizing and reconfiguring itself based upon extensions and tools selected by the user. This new device must support streamlined maintenance for next-generation composite aircraft.

Background SURVICE Metrology is a specialist in combat system survivability, weapon

system effectiveness, and system safety. This particular division of SURVICE is expanding upon the company’s use and expertise with high-end laser-based dimensional inspection equipment, and has established a substantial R&D capability, and is currently working a number of US DoD research grants. Metrology has been used successfully in identifying the location and extent of damage on combat vehicles. SURVICE Engineering has been pioneering the use of a metrology vector bar and accompanying system to accomplish this.

SURVICE Metrology has already fabricated a prototype out of preexisting hardware that is able to locate a point in three-dimensional spaces and with the click of a button store this information for analysis. The current hardware has been either purchased from other companies (e.g. Metris) or engineered by SURVICE itself. To make this setup completely marketable by SURVICE, their goal is to make their own set of metrology hardware. This marketability depends on fulfilling the needs of the consumer; this product needs to be easy for one person to use and functional as well. It

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also should have interchangeable tips for various applications to be determined by the customer. With the extra functions of a multi-functional mouse button, LED lights, and USB interface system, the new and improved design of their vector metrology bar will be able to sell throughout the US Defense system and other commercial uses.

Design Process The design process was broken into three parts. The first part was to establish

design requirements and the project scope. The second part was concept selection and the third part was the detailed design. These portions were completed in order to facilitate designing the most appropriate prototype for this project.

The basic criteria provided from SURVICE at the start of this project was, “to improve the set-up and use of the iGPS laser-based metrology system vector bar.” This was elaborated on and the following was provided, “the intent is to develop a next-generation system that automatically recognizes and reconfigures itself based upon extensions and tools selected for use to support streamlined maintenance of next-generation composite aircraft.”

After discussing these statements as well as the customer wants, we were able to compile a list of metrics that fit the project scope. The key customer wants for this project included: supporting removable/reconfigurable tips, relocation of iGPS sensors, integrated multi-button operation through use of I/O USB, multi-color LED indication lights, consolidated wiring and certain aesthetic requirements. From these wants the metrics were decided; these are discussed in detail during the testing and analysis portion of this report. See Figure 3.

We were then able to come up with a design statement for the project; this statement went through several iterations as the scope of the project became more clear and was altered slightly throughout. The final design statement became, “To improve upon current metrology vector bar by implementing ergonomic features and decreasing errors due to human factors.”

The concept selection portion of the design process is when we were able to define our project direction. Using UDesign, we ranked our concepts based on customer wants as well as device metrics and came to conclude our “Vector Bar with Pistol Grip” concept would be our final design. This concept was chosen after taking into account the

Figure 1

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changes requested by SURVICE during phase 1 of our customer wants.

The detailed design started with maintaining the alignment of the main bar. A strong direct connection from the iGPS sensors to the tip ensures that the reading will be accurate. The main bar of the design is machined from aluminum with holes and threads for attaching the handle and sensors. The mini vector bar produced by Metris is usually attached using a press fit. For our purposes we needed an assembly that could be easily disassembled for testing and addition of parts. Making use of the female threads already in the mini vector bar we fastened it to the main bar with a bold and washer. This is to be tightened until the mini vector bar is firmly secured to the aluminum bar.

The customer want of a quick connect tip was taken into account in designing the front of the main bar. Each tip can be attached via a sleeve screw. The sleeve screw contains a little lip at the top that both centers the tip as well as firmly holding it in place. For easier grip the sleeve is knurled on the outside. This screws into the front of the main bar using fine threads for better grip.

Each tip holder itself is made to contain the hardware the user desires as well as its own recognition sensor. With each tip the machine vector bar needs to be calibrated as well as the correct software opened. Putting a set of sensors into each tip attachment would allow the computer to acknowledge what tip has been attached and take correct action to open programs and calibrate the bar’s length. The sensors will communicate to a USB I/O interface located in the handle. The USB device we are using reads voltage changes. By placing a set of contacts on the front of the main bar we can read which tip is being attached. The tips themselves will have a

piece of conductive material to bridge this gap and complete the circuit. A rubber

layer is placed beneath these sensor pads so that when the tip is tightened onto the main bar it pushes the contacts flush. The Metrolgy Vector Bar will have a total of three sets of contacts giving the possibility for multiple tips.

Since the handle will be our most detailed shape we decided it would be best to have this part rapid prototyped. Inserting the holes for the buttons and LEDs is most easily accomplished with this part. Our customers wanted at least two buttons and two

Figure 2

Contact Sensors

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LEDs. The buttons are accessible to the thumb and index finger. LEDs are placed on the side in easy view for the user. Both are to be wired to the USB interface for the computer to read. Built into the handle is a gap for the USB interface as well as the wires. This is given easy access by unscrewing the handle apart. All wires are run through the handle and out of the bottom. The handle also has room for the wires coming from the USB, Ultrasound Transducer, and the iGPS sensor. These wires are covered by durable plastic sleeve that not only protects the wires but holds them as one making it easier for the user. Exercising our ability to produce more detailed geometry with a rapid prototyped part, there is a wire cover gripping ledge. Once the handle is fully assembled the ledge grips the wire cover and prevents the wires from being ripped out.

Ergonomic features were added to the handle as well. Holding the vector bar in this manner is referred to as a power grip. Ergonomics dictates that this grip should be no longer than five inches long and having a width of one inch. The placement of the ridges for the fingers took much iteration. Removing the bottom ridge holds the pinky and ring finger together to stabilize the grip of the middle finger above. This leaves the index finger and thumb free to interact with the buttons. Since the hardware the vector bar contains is very expensive and fragile a strap is located at the base of the handle. This wraps around the user’s wrist and acts as a fall arrest system in the event the user releases their grip of the handle.

Numbered Subsystems

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1. The handle grip: This sub-system is made out of two parts. One part is labeled in the drawing package as “Handle Main” and the second part is labeled “Handle half”. The handle main will hold together the pieces of the handle grip which include the LED lights, a USB interface microchip, and the trigger buttons. The handle half will cover the other side of the handle to make it easy and comfortable to grip. The handle grip will contain the BNC cable or the co-axial cable from the ultrasonic sensor tip and the cable wire from Metris’ sensor. The left side and the front of the handle grip will have trigger buttons that will be positioned for index finger and thumb usage.

2. The main hollow cylinder: This subsystem is to be manufactured in machine shop by using the drill machine, lathe machine, and milling machine. The material the main hollow cylinder will be made out of aluminum. The rear of the main bar includes a hole for the attachment of Metris’s Mini Vector Bar. It can be either fastened or press fitted into the main bar but for our purposes it has been fastened for easy removal and assembly testing. The main hollow cylinder will contain the BNC cable/ co-axial cable from the UT sensor and the cable from Metris’ sensor. The main hollow cylinder will have two LED lights placed on the left side of the cylinder placed on the handle grip.

3. Tip quick connection: This sub-system consists of four main parts and one interchangeable part. The four main parts: the main bar tip sensor, tip sensor transducer, transducer holder, and a threaded ring. The main bar tip sensor and the tip sensor transducer will be made out of plastic and with metal contacts. The transducer holder and the threaded ring will be rapid-prototyped out of ABS plastic. The ultrasonic sensor tip and the pointy sensor tip will be interchangeable.

The tips sensor includes a switch made up of a conduct panel as well as a set of leads Imbedded into plastic below. This functions similar to the key recognition on a keyboard. When the button is pressed the conductive panel bridges the gaps between the circuit below. The computer then senses a voltage increase and registers the button as being pressed. The metrology vector bar’s tips will function similarly so that when the tip is secured onto the front the metal contacts converge and complete their circuit. The sensor tip will have a total of three sets of contacts leading to a possibility of eight different tip arrangements for the computer to acknowledge. Each interchangeable tip has a peg that keys into a

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hole located on the main bar. This makes sure that the contacts are oriented correctly while tightening the sleeve screw.

4. Metris IGPS sensors: This subsystem is a ready-made product. It is being ordered from Metris. The product that Metris is selling currently has its cable wire coming out of the side of the bottom sensor (as seen in Appendix A). Ideally the cable wire should come from the back of the sensor. Therefore before ordering the sensor there is an inquiry as to an estimated cost for a customized sensor that has the cable wire coming out of the back of the sensor bar. Future production idea is to allow SURVICE to fabricate a contract with Metris to bulk produce the customized sensor that is ideal for the prototype design.

Testing and Analysis In order for us to be able to determine how well our final design solves the initial problem assigned to us, the team set up metrics at the beginning of the project. These metrics were used in the design process to restrict our concepts to those that would most effectively satisfy the target values. During the fourth phase of our project, we tested the metrics within the scope of our project. The “accuracy of measurement” metric is to be tested by SURVICE Engineering once all electrical components are installed and working properly. Testing the accuracy of the device requires extremely accurate testing methods and a long amount of time that would fall outside the timeline of our project. Since the vector bar is so short and because the sensors are vendor purchased, our team as well as SURVICE have no doubt that the accuracy metric will be met.

The ergonomics of this design became a dominant aspect of the project. Once the customer’s wants were analyzed and ranked, it became clear that though ergonomics

Metrics Target Values Length of entire Vector Bar

Less than or equal to 12”

Diameter of Vector Bar Less than 1.5”

Weight of Vector Bar Less than or equal to

3 lbs Number of Wire Ports 1 wire port Number of Mouse Buttons 2 buttons Length between sensors Less than 6”

Stability of Object

Center of gravity located at the user’s

hand Alignment 0°

Complexity of device

Less than 5 components/ subsystems

Assembly Time Less than 1 minute Rigid 1 mm Strength 10 Mpsi Accuracy of measurement Greater than 2mm Cost of Prototype $10,000

Figure 3

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did not fit into a specific metric, it was an important part of the outcome of this project. SURVICE was consulted prior to the first iterations were made and a few basic guidelines were established with respect to the handle. Foremost was the section on the amount of buttons present (2) and also that it was acceptable to design the handle be a right handed tool.

Due to the nature of ergonomics themselves, this was a feature that could not be, in a sense, tested. To overcome this barrier and come up with a sound solution, this portion of the project was completed in iterations. Different design iterations were made and feedback, from a variety of sources, was gathered and then design changes were made to encompass that feedback.

The first iteration was made from clay models. These models were analyzed by Team SURVICE and changes were made based on this analysis. The second and third iterations were models made by 3D printing based on SolidWorks designs. The second iteration concentrated on getting finger placement groves and button placement correct. Along with Team SURVICE analysis, the University of Delaware Biomechanical department was consulted and was able to provided professional opinions. They were also a source of anthropometrics information. Using this information the third iteration was completed.

The third iteration had a variety of changes. The first was a change in the overall circumference and length of the handle. These were changed to fit into anthropometric information concerning the hand; these figures were taken from Occupational Biomechanics by Chaffin and Anderson. To meet the circumference measurements, the depth and width of the handle were both changed. The length was influenced by shortening the overall handle length but also by combining the space provided for the fourth and fifth phalanges. This allowed for a better grip for a wider variety of hand sizes. The final change to this iteration was to change the angle at the top of the handle to enable the base of the thumb and wrist to be more weight bearing.

The final iteration, as seen in the prototype, reflects changes made after consulting was SURVICE engineering. This prototype was made from ABS-30 blue plastic by RedEye. The trigger button was changed from a squared raised button to a flat circular button to match the thumb button. A groove was introduced into the top of the handle to facilitate a wire coming from the transducer into the handle.

To satisfy the “stability of the object” metric, the team physically and computationally tested the final

Figure 4

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design. Using SolidWorks, the center of gravity was determined to be 2.33 inches behind the centerline of the handle (See Figure 4). To physically test the stability of the vector bar, we used a thin wire to balance the bar. The wire was placed at multiple locations along the bar until the vector bar remained level. By testing the final design with the wire, we determined the center of gravity to be around 1.75 inches beyond the centerline of the handle. Although we did not achieve our metric, the weight of the object is much lighter than expected and thus a much smaller moment is applied to the user’s hand.

Some of the metrics were straight forward and easy to test. The length of the vector bar, diameter of the vector bar, number of wire ports, number of mouse buttons, and length between sensors all met the target values. The total length of the bar is 12”, the diameter is 1”, number of wire ports is one, number of mouse buttons is two, and the length between the iGPS sensors is 5”.

The most important metric in our testing and design processes was the weight. If the final design was too heavy, the user’s arm would quickly fatigue and defeat the purpose of creating a new vector metrology bar. Our target value for the weight was to be less than 3 pounds since that is the approximate weight of the existing mini vector bar. After the final design of our vector bar, it was placed on a scale and determined to weigh slightly less than one pound. Having the vector bar weigh less than one pound is a great achievement since it compensates for the center of gravity being slightly off center. Multiple subjects used the vector bar as if they were registering points in a three dimensional space and experienced virtually zero fatigue after 45 minutes of performing the activity.

To determine how easy it is to exchange tips on the vector bar, we timed multiple subjects as they removed a sensor tip and attached another. The results from the test are shown in Figure #5. When compared to our target value for our assembly time metric the test results show all subjects were able to remove and then attach a tip in less than the

target value of one minute.

Test Recommendations Since the scope of this project did not include interfacing to the computer systems and software used, this multifunction vector bar could not be tested to determine if main function, accuracy, was accomplished. This will be done by SURVICE metrology experts. The testing should be done to determine if the accuracy of the product was in the range that was expected. So do this, we suggest comparing

Trial Assembly

Time 1 57 seconds 2 52 seconds 3 56 seconds 4 45 seconds 5 50 seconds

Figure 5

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data obtained using the multi function vector bar to data gathered using a validated, previous version of the vector bar.

Prior to determining accuracy, linearity must be tested. Though we were able to measure and determine linearity, this prototype will be sent to METRIS, as is the case with all metrology products used to be calibrated. Once METRIS receives the vector bar, they will perform calibration test to determine the exact relationship between the tip and the two iGPS sensors. After METRIS completes the calibration of the vector bar, the vector bar is potentially ready for customer use. METRIS will supply instructions on how to recalibrate if there is some need to do so.

Cost Analysis The budget for this project had a ceiling of $10,000. This number was chosen to

ensure the end project would be economically feasible for when the prototype was put into production. Taking this into account, the team benchmarked products that could be used in the final prototype. Most parts that went into the vector bar were prefabricated items and off the shelf parts. The only machined parts that are used are the hollow chamber of the vector bar, and the sleeve screw at the tip.

The main portion of the budget went into the iGPS sensors and the ultra sonic tip. Both of these products will be purchased through outside vendors. The iGPS technology has been spearheaded by Metris, a company which is involved in the grant process with SURVICE.

The ultrasonic sensors were available through various vendors. We consulted Dr. Dirk Heider of the Composites Materials Lab to gain a bettering understanding of the technology behind the product. Dr. Heider was able to advise us concerning the right sizes and geometry for our needs. He also informed us on the various different tips that could be used for this application and additional design ideas that could be incorporated that were not in the original customer wants.

Off the shelf products that were used in the vector bar included various items that are all part of the costumer wants. LED lights were chosen to be used as indicators for system readiness and operation. Slightly rounded push buttons were chosen for “mouse buttons” to replace the squared, raised button that is currently in use based on operators

Actual Cost Prototype

Cost

iGPS Sensor 4950 4950 Transducer 420 420 Rapid Prototyping 343 343 Hardware 116.84 408.05 Aesthetics 49 49 Totals 5878.84 6170.05

Figure 5

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request for a permanent and more ergonomic design. A USB I/O interface was implemented into the casing as per customer wants.

Material costs were also an issue discussed with sponsor. Past vector bars were made with carbon fiber to increase accuracy due to the need for rigidity and linearity of the vector bar. For the specifications set forth for this vector bar, precision accuracy to that degree is less of an issue and therefore that level of rigidity is not necessary. The material chosen for the prototype hollow chamber was aluminum which was machined by Team SURVICE in the student machine shop.

The handle was made by an outside vendor. It was rapid prototyped by the company, RedEye. We chose this route for the production of the handle due to the complexity of the part. Other costs that would have been accrued would have been the first three iterations of the handle through the same procedure. These costs were not a factor in the prototype due to the availability of the rapid prototyping at the University of Delaware. See Figure 5 and appendix for exact cost breakdown.

Path Forward The final prototype has slight variations to what we would suggest for mass

production of our multifunction vector bar. These differences were necessary due to time constraints and product availability. The first difference would be with the iGPS sensor that was chosen. The model that was used in the prototype was chosen due to availability. The actual production model should take advantage of the availability of a custom made iGPS sensor. The custom sensor should minimize weight and reduce length. The custom bar would also have a connection wire that exited the iGPS sensor through the attachment point to the main hallow cylinder in contrast to the current wire that exits thru a side port that must then be rerouted into the hallow chamber.

Secondly, the ultra sonic transducer (UT) sensor chosen would also have a wire port that exited through the back of the UT sensor. This would alleviate the need as discussed above for wires to be rerouted back into the hallow chamber.

Thirdly, the material choice for the multifunction vector bar handle. We used a rapid prototype ABS plastic for the prototype that may not be the best choice for mass production. Since the number of actual products that would be produced is unknown to us, we cannot make a sound decision on the best type of production for this part. The complexity of the part precludes some productions options but others such as casting and injection molding would be an option.

Conclusion After multiple iterations to our handle and other parts of the design, we have developed a highly improved vector metrology bar for SURVICE Engineering. The

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design incorporates new features such as: LED’s, multiple buttons, interchangeable tips, a USB interface, and a tip recognition system in order to make the vector bar more ergonomic and easier for the customer to use. All metrics capable of being measured by our team have been met including the weight. We initially projected the bar to weigh around 3 pounds but our final design is slightly less than 1 pound. Having the vector bar weigh only 1 pound, allows the user to work longer periods of time with little to no fatigue in their arm and wrist. Testing the accuracy of the vector bar will be done by both SURVICE and METRIS. METRIS will first calibrate the bar then SURVICE will determine the accuracy of our design. This will not be an issue with our project since our design is only 12” long and the iGPS sensors will supply adequate accuracy for that short of a length. More iterations may be made in future months after NAVAIR and SURVICE Engineering use our prototype in the field.

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Appendix A SolidWork Design Photos

Final Prototype

Sensor Tip Connection

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Mini Vector Bar Sensor Fastening

Mini Vector Bar

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Appendix B Final design photos

Exploded View

Main Bar Sub System

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UT Tip in holder

Inside multifunction vector bar

Final Prototype

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Appendix C Cost chart

Part Actual Cost Prototype

Cost iGPS sensor 4950 4950 UT Sensor 420 420 UT holder 68 68 Handle 257 257 LED Lights 3.36 84 Buttons 8.37 13.45 Engraving 48.98 48.98 Sleving 2.37 2.37 Screws 26.74 77.68 MicroDot cable 41 41 USB 35 35 Random parts 154.55 Sub totals 5860.82 6152.03 AL Bar 20 0 Student Time 0 3120 Shipping 186.13 186.13 Total 6066.95 9458.16

Appendix D Detailed Design-Subsystems

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Appendix E Concept Selection

Concepts Concept Descriptions Benchmark Current Metrology Vector Bar

A Vector Bar With Pistol Grip B Vector Bar With Pistol Grip and Trigger C Vector Bar With Raised Area for Buttons

Benchmark A B C Metrics % Target value Length of entire Vector Bar 16 <11" 11" s s s Weight of Vector Bar 16 <48 oz 48 oz u u u Number of Mouse Buttons 13 2.0 1 b b b

Stability of Object 12 Balanced at

handle Close to Balanced b b s

Complexity of 8 Anyone Can Experience b b b

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device Use Needed Alignment 8 Linear Linear s s s Assembly Time 6 <1 min 1 min b w b

Strength 5 withstand 5'

drop withstands 5'

drop s s s Diameter of Vector Bar 4 <1.3" 1.3" b b b Number of Wire Ports 3 1 2 b b b Temperature Resistance 3

Indoor & Outdoor

Indoor & Outdoor s s s

Rigid 3 Never Bends Never Bends s s s Accuracy of measurement 2 <2mm .1mm w w w Length between sensors 1 <6" 6.75" b b s Cost 1 <$10,000 $5,000 s s s Better than benchmark 7 6 5 Worse than benchmark 1 2 1 Same as benchmark 6 6 8 Unknown relationship 1 1 1

Score 0% 52.2 40.2 41.8

Concept B

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Appendix F

Ergonomic handle iterations

First iteration

Second Iteration

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Third Iteration

Final Prototype Handle