Multi-Disciplinary Senior Design ConferenceKate Gleason College of Engineering

Rochester Institute of TechnologyRochester, New York 14623

Project Number: P09011

APPARATUS FOR VISUAL AND AUDITORY OBJECT RECOGNITION (VAOR) STUDY

Andrew Chorney / IE-Project Manager Jason Hess / Industrial Engineer

Michael Goldberg / ME-Lead Engineer Mahmudul Khan / Electrical Engineer

Timothy Bukowski / Industrial Engineer Martín Martínez / Mechanical Engineer

ABSTRACT

The primary goal for this project was to design an apparatus that would be used to present three-dimensional objects in a match-to-sample procedure to assess the visual and auditory perception abilities of beluga whales. The apparatus was constructed for use in a research project organized by the project’s customer, Dr. Caroline DeLong of the Psychology Department at the Rochester Institute of Technology. Dr. DeLong is the principal investigator for this research project, which will take place at Mystic Aquarium in Mystic, Connecticut. Specific requirements were provided by the customer at the beginning of the project. The final deliverables for the project included a functioning, transportable apparatus, along with two complete sets of test objects and a completed operator and service manual. Several concepts were developed, investigated, and refined, including electromechanically powered options. As the project developed, more requirements and constraints were added. The final design incorporated a fully mechanical configuration, forgoing electronics as a means of increasing reliability, reducing cost, and simplifying manufacture.

INTRODUCTION

Marine mammals (odontocete cetaceans) use biological sonar (i.e. echolocation) to navigate, identify prey, and avoid predators. Echolocating animals project broadband high-frequency sounds into their environment and listen to the returning echoes to

determine the location and structure of objects. The returning echoes are complex and can vary along many parameters such as frequency spectrum, time structure, and amplitude. The echolocating animal must extract object feature information (e.g., size, shape, material) from these acoustic parameters of echoes to identify the object. The goal of Dr. DeLong’s research project is to determine how echolocating beluga whales extract object feature information from the acoustic parameters of object echoes. This is done using a method called match-to-sample (MTS). In the MTS task, the animal is shown a sample object (e.g., sphere), the sample object is removed, and then the animal must choose an object identical to the sample from among two or three choice objects (e.g., a sphere, cube, and cylinder). The beluga whale indicates its choice by touching the object with its nose.

The previous apparatus did not allow for effective double-blind testing on a single beach. The previous apparatus also did not allow for a short time between the display of the sample object and choice set, a factor that directly relates to the whale’s ability to complete the MTS procedure successfully. It was determined that a more refined apparatus that shielded the objects from the trainer’s view and allowed for fast changing between object sets was required in order to gather accurate and defensible data on beluga whales’ use of echolocation. Along with building a new apparatus, a comprehensive set of objects would also need to be produced.

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NOMENCLATURE

ECHOLOCATION - the process by which marine mammals (odontocete cetaceans) use sound to obtain information about their surroundings.

MATCH-TO-SAMPLE (MTS) – a process used to test an organism’s ability to recognize objects.

POLYVINYL CHLORIDE (PVC) - Thermoplastic material often used in plumbing applications due to its resistance to corrosion.

80/20 – An extruded aluminum structural framing system ideal for prototyping. The product line includes a variety of extrusions and many fastening options. Extrusions feature t-slots for mounting, allowing easy reconfiguring of designs.

CENTER OF MASS (COM) – The point on the apparatus where the total system mass appears to be concentrated.

NEEDS

The customer need of greatest importance was in regards to the overall safety of the apparatus and objects for both the operator and whale. This included ensuring that there were no sharp edges on the apparatus or objects. In addition, all objects were required to be of sufficient size so as not to pose a choking hazard to the whale.

The apparatus also needed to be visually and auditorially nondistracting to the whale to ensure that no additional variables were introduced during testing that could lead to inaccurate or inconsistent results.

The apparatus and objects needed to stand up to the environment in which they would be used. This included ensuring sufficient durability, weatherproofness, and salt water resistance. Because the apparatus could not stay out on the beach permanently, the design needed to incorporate features that made certain the ability of the apparatus to survive the wear and tear associated with being moved around, assembled, and disassembled on a daily basis. Corrosion in the form of rust is considered a safety hazard to the whale, so all parts needed to be rust-resistant. In addition, the apparatus and objects were required to be resistant to degradation from the testing environment, including salt water and UV rays.

Other needs related to the construction of the apparatus included being built from easily replaceable parts as a means of simplifying repairs should they be required. Also, the final design needed to be visually pleasing, since the apparatus would be in use in areas visible to the public. The apparatus needed to fit on and be nondestructive to the beach area, be stable on the uneven surface, require no external power, and be easy to set up rapidly.

There were several needs related to the operation of the apparatus. The ability to operate in

both hidden (double-blind test) mode for data collection and non-hidden mode for the training phase was required. The ability to be setup rapidly and operated by a single person was paramount, since there would only be one person available to perform these tasks. The ability to display objects both above and below the water was necessary, so that visual-only testing could be performed. Finally, the interval between the display of the sample object and choice set needed to be adjustable.

Finally, there were requirements for the objects as well. These including a minimum and maximum size and weight, as well as the requirement that the objects sink in a nondistracting and even manner while working well with the apparatus.

SPECIFICATIONS

Apparatus PerformanceMetric Units ValueChoice-to-Set Change Sec 3Test-to-Test Change Sec 90Apparatus Module Weight Lb 40Object Weight Lb 5Minimum Object Dimension in 6Maximum Object Dimension in 12Maximum Width in 92Maximum Depth in 32Maximum Height in 48Distance from Edge in 12Depth into the Water in 6-24Setup Time min 5-10Table 1: Apparatus and Object Specifications

Object Set CriteriaDifficulty # Size Material ShapeEasy 18 Vary Vary VaryIntermediate A 4 Vary Same VaryIntermediate B 4 Vary Vary SameIntermediate C 4 Same Vary VaryDifficult D 4 Same Same VaryDifficult E 4 Same Vary SameDifficult F 4 Same Same VaryTable 2: Object Specifications

CONCEPT & EVALUATION

Of the six initial concepts, the team chose to pursue the concept shown in Figure 1.

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Figure 1: Selected Concept

The concept pictured in Figure 1 was presented at the system level design review. The design incorporated a battery-powered electronics system which powered two linear actuators. These actuators raised and lowered the arms as shown. The apparatus would rotate around its base to switch between object sets. The team was most confident in its ability to construct this concept, which appeared to meet all design criteria and be the most robust.

After guidance from Professor Wellin, Dr. DeBartolo, Dr. Robinson, and the customer, Dr. DeLong, it was determined that the proposed concept would likely not meet the required time between display of object sets. Since a reduction in this time over the previously used apparatus was one of the primary motivators for the existence of the project, it was suggested that design refinements be made to try to further reduce the time between the sample object and choice set.

The reviewing parties questioned the portability and stability of such a large single piece of equipment. After further development, the previous concept evolved into the concept shown in Figure 2.

Figure 2: Design presented to Mystic Aquarium

The concept used dual motors to actuate the objects into and out of the water. These motors were to be powered by a 12V sealed lead acid battery stored in a box at the rear of the apparatus and mounted on a removable frame. The motors would be radio controlled from a remote and powered through pulse width modulation variable speed motor controller hardware stored in an IP4X submersible container, also mounted at the rear of the apparatus.

The base incorporated a 17 gallon drainable bucket, intended to be filled with water as a means of providing weight for a stable base platform. The water would be added once the apparatus was brought to the beach, and drained before being moved.

This concept was presented at the detailed design review and, with minimal required changes, was approved by the customer. After review by Mystic Aquarium, the apparatus was determined to be sufficiently safe for use, contingent upon an in-person inspection on location by aquarium staff.

After further development, it was determined that the electrical functions should be removed and replaced with a human powered method of object actuation. This decision was driven primarily by concerns about cost and reliability. It was felt that there was not enough confidence that if the electronically powered version was built, the system could be tested and sufficiently perfected, given the time allotted during Senior Design II. It was also felt that remote controlled functionality, while convenient, was not vital to the operation of the apparatus and could potentially cause it to be less reliable.

As a final design change, the motor system was replaced with ergonomic handles connected to the same cables that had previously been connected to the motors.

To address the portability concerns from the previous design review, it was decided that the new concept would assembly from a series of individual modules, designed to mate and unmate easily from one another. This would split up the size and weight of the apparatus to ease moving and storage, but would allow for a single solid structure during testing. The final apparatus design included three separate modules, which when fully assembled and loaded, weight 272lb, but when disassembled can be easily moved by one person in three trips.

Base FrameThe base frame contains a large plastic

bucket designed to be filled with water. The bucket features a spigot at the bottom for drainage. The pail is surrounded by a frame constructed of 80/20 mounted on leveling feet, and has mounting points for the drive frame to attach on the top . The base also features large eyebolts to allow tethering the apparatus to a nearby sturdy object for additional stability. The base

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weighs a total 41 lbs without water. With water the base weighs 186 lbs.

Figure 3: Apparatus Base

Drive FrameThe Drive Frame allows the operator to

control the position of the objects over the beach and water, in the raised and lowered position, and into and out of the water. It consists of a flat base platform, a turntable, and an upper section which interfaces with the object frame and facilitates the raising and lowering of objects by the operator. Thumb screws connect the drive frame to the base frame. Parallel arms support the slides, cables, pulleys, and safety latch. The actuation of the arms is assisted by two gas springs connected by clevis pins. The drive frame weighs 38 lb.

Figure 4: Apparatus Drive Frame

Object FrameThe Object Frame mounts to the front of the

drive frame. The object frame is constructed of PVC

and 80/20. Thumb screws attach the object frame to the drive frame. The objects are attached to the slides on the drive frame via stainless cables. The objects are concealed to hide the objects from the view of whale and the operator. The object frame with the MTS objects weighs 49 lb.

Figure 5: Apparatus Object Frame

ANALYSIS

SolidWorks and COSMOSWorks were the main tools used by the team for design and mechanical analysis.

Center of MassThe location for the customer’s testing

platform is a concrete beach at Mystic Aquarium at the edge of the beluga whale tank. Despite the beach not being flat and the aquarium not allowing the installation of any permanent anchors on the beach, the apparatus must be stable. For the team’s purposes, a state of stability is defined as the center of mass (COM) being located inside the footprint of the apparatus as shown in SolidWorks. When the COM extends beyond the footprint and the apparatus is not fastened to the ground, the apparatus is considered unstable.

Center of Mass for a continuous constant density object is calculated using the following formula:

R⃗= 1M ∫ r⃗ dm

(1)

Where R⃗ is the vector of the total COM from the

reference origin, M is the total mass, and r⃗ and dmare the vector and mass, respectively, of a differential element.

When the object becomes individual particles, the formula converts into:

R⃗=∑ mi r⃗ i

∑mi (2)

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The original concept had most of the electronic equipment located close to the center of the base, with the battery mounted on an arm extended away from the beach. Converting the base to a large bucket to be filled with water before each setup helped to bring the COM inward and allowed the apparatus to be more portable by emptying the bucket at the end of the testing period. SolidWorks was used to perform the COM calculations and create the images showing the location of the overall COM (indicated by the white dot).

Figure 6: Side View showing COM

Figure 7: Top View showing COM

The COM is located inside the foot print of the apparatus base, meaning the apparatus is stable. However, this is only accomplished if the operator fills the base with the maximum amount of water. The COM is close to the front of the footprint, therefore in a dynamic loading situation with minimal force applied either at the top of the drive carriage or object frame, the apparatus could become unstable. After further discussion, it was determined that a tethering

solution would be designed and used as a means of providing additional stability.

The Drive Frame is attached to the base on the right side, and as it rotates to the left, the COM shifts. The offset mounting location allows the entire apparatus to remain stable.

Gas SpringsThe apparatus needed to be able to display

the objects above the water. Also the objects need to be lifted to a height sufficient to clear the beach when rotated. The drive frame has two positions, and assistance to raising the frame to the upper position is provided by two gas springs, each with 130lb of force.

Sum of the Moments was used to find the necessary force of the gas springs to produce an acceptable force required by the operator’s hand to actuate the frame.

M⃗=F⃗×d⃗ (3)

A moment, M⃗ , is calculated by crossing a force, F⃗ ,

with a distance vector, d⃗ , from the point of interest.To analyze the drive frame, we need to calculate the sum of the moments. The team analyzed the system in a static state, by creating an arbitrary hand force applied at the locking mechanism.

∑ M⃗ O=m⃗i=I α⃗=0(4)

FH=mgsin θC×40in- 2FS sin θB×9 .5in

DH sin θA (5)

Figure 8: Geometry needed for Sum of Moments

Gas springs are available in increments of 10lbs of force, so the theoretical force analysis was performed in increments of 10lbs to determine which size spring would be most ideal. When the hand force is negative, the gas springs are strong enough to support the parallel arm system. Microsoft Excel was used to step through degree increments to produce the following plot.

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0 1 2 3 4 5 6 7 8 9-40-200

20

Required Hand Force, Max Weight FH,100

FH,110FH,120FH,130

Gas Spring Extension (in)

Forc

e (lb

s)

Figure 9: Chart of Necessary Lift Force provided by User

OBJECTS

There are a total of seven sets of objects. Each set of objects is unique in such a way that they are different in size, shape and material, as shown in Table 2. The first set consists of 18 easy objects that vary in size, shape and material. The purpose of this set is to have the whales become more familiar with the match-to-sample procedure. The other sets are classified as either intermediate or difficult for the whale to distinguish. Intermediate objects vary by 2 parameters, and difficult objects vary by 1.

Set A, still pending approval from veterinarians at Mystic Aquarium, consists of steel covered in foam and protected by marine-safe rubber coating. The objects all vary in size and shape.

Set B consists of PVC schedule 40 pipe fittings forming a ‘twisted I’ shape. Each ‘I’ increases in size incrementally, based on standard PVC sizes, and is filled with different materials, including sand, gravel, metal shavings, and water.

Set C consists of flat objects. All objects have identical volume and surface area but vary in material. The materials used include aluminum, acrylic, nylon, and PVC.

Set D consists of stainless steel bowls filled with sand, with tops secured with structural adhesive.

Set E consists of aluminum bottles filled with different materials, including sand, gravel, water, and metal shavings. The bottles are sealed with silicone to ensure the fillings do not spill into the tank.

Set F consists of PVC objects constructed from the same set of 1 inch pipe fittings. The fittings are: a cross, two tees, four elbows, and six end caps. Using the same fittings creates the same size object. All are filled with sand.

There will be a total of two sets of 42 unique objects.

CONSTRUCTION

Before the team received the 80/20, it was machined to the designed specifications. The proper

number of brackets and other fasteners were ordered to construct the apparatus.

The 80/20 met the needs of the team’s build effort. The added expense, versus less expensive box channel, proved valuable to the team as many modifications were made during construction that could not have been foreseen during the design phase. The majority of the building of the apparatus and most of the objects was performed by the team in the machine shop and at the Senior Design Center at the Kate Gleason College of Engineering.

The Brinkman Lab used CNC milling to cut out the flat plate objects in the easy set and for set C.

TESTING

Pool TestingSince Mystic Aquarium is located a great

distance from RIT’s campus, the preliminary testing of the apparatus and objects were done at the RIT swimming pool. Initial testing showed that the apparatus worked well but needed various refinements. Figure 10 shows the apparatus being testing at the RIT swimming pool.

Figure 10: Testing being performed at the RIT Pool

While testing the apparatus, it was decided that there were two main problems that needed further consideration. Since there was a lot of weight in front of the apparatus, both the turntable and the drive frame uprights were deflecting under the stress from the high loading. A new, more robust turntable was designed and built as a replacement. Made from 6061 aluminum plate and stainless-steel ball bearings, this successfully replaced the previous turntable.

The original drive frame upright was made of a 1”x1” extrusion. It was successfully replaced with a 1”x2” extrusion with twice the bending stiffness of the original component. After the replacement design was installed, it was determined to sufficiently solve the problem.

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Filling tub

Emptying tub

Setup time

Changing sets

Raising and lowering 

of objects

Disassemble tim

e

Trial 1 53.6 457 602 53.5 6.2589

Trial 2 36.8 462 581 51.6 6.7596

Trial 3 45.2 450 591 38.9 4.8621

Trial 4 47.5 487 624 45.6 5.5605

Trial 5 41.6 455 596 47.8 4.9599

Average

44.94

462.2

598.8

47.48 5.62

602

Table 3: Pool Testing Results. (All times are in seconds)

TurntableAfter a period of several tests, it became

apparent that the turntable purchased from McMaster-Carr did not support the moment load created by the object frame or objects. The team assumed the turn table would support the moment given its 1000 pound compressive load limit rating, however the turntable was constructed of thin gauge galvanized sheet steel and the carbon steel ball bearings sat in grooves that were not sealed.

The team, assisted by Professor Wellin and Edward Hanzlik, designed and built the replacement turntable shown in Figure 11. It consists of two 3/8” 6061 aluminum plates, captivated by a 3/4” diameter shoulder bolt and two nylon-insert lock nuts to ensure there is no separation. Smoothness of rotation is provided by an enclosed ball bearing, supported by 20 individual 9/16” bearing balls retained in a custom designed ½” PVC ball retainer. The bearing balls adequately support the high moment load. The top and bottom plates have holes that are used to mount the turntable to the drive frame.

Figure 11: Opaque Model showing all components

COSMOSWorks was used to perform a deflection study on the turntable plates. In the model shown in Figure 12, the 3/8” thick 6061 aluminum

plate resulted in a maximum deflection of about 1mm. This was confirmed in real world observations.

Figure 12: COSMOS Output showing maximum displacement

Drive Frame UprightDuring testing, deflection was observed in the

drive frame upright, which supports the entire overhung load of the apparatus. After several trials, it was noted that plastic deformation had occurred in the upright and it was decided that the upright should be replaced with an extrusion of higher bending stiffness. The replacement was completed and solved the problem.

Mystic Aquarium TestingOn May 15, 2009 the apparatus was brought

to Mystic Aquarium to do testing on site. The apparatus and several objects were carried to the beach and the apparatus was assembled. The whale trainers examined the apparatus for any sharp edges. After having examined it for safety, several of the objects were used to operate the apparatus. The trainers were pleased with the functionality of the apparatus. The objects were also examined in detail to ensure they met all the safety requirements. Several of the objects needed to be rebuilt for safety reasons. After having gone through several trials of operating the apparatus, the trainers had some suggestions for modifications.

UsabilityThe apparatus was designed to be user-

friendly during the setup, operation, and disassembling process. The apparatus and each of its components are able to be carried and operated by a female between the ages of 20-40 years old. All of the components are less than 49lbs and can be carried approximately 75ft to the location of the pool. Allowing the operator to carry multiple objects to the test location, each object was designed and built to be less than 5lbs. In containing the objects, bins were supplied to assist the operator in transporting multiple objects without any issue of strain on their back and arms. The drive frame was designed to allow the operator to fill the tub with a five gallon bucket approximately five times.

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During the match test sample process, there are some key features that allow the operator to perform the procedure without using any extraneous force. Gas springs were installed on the drive frame to allow it to raise the object frame above the water with minimal force applied by the operator. A turntable was incorporated into the design as a means of rotating the drive frame with minimal effort. In addition, a component was added to stop the turntable at the exact point at which the apparatus is positioned for testing. Thumb screws were used to provide an ergonomic method of installation and to decrease the setup time. The thumbscrews were permanently attached to the apparatus to increase the speed of setup and decrease the chance of loss.

With the triceps muscle being larger and stronger in force than the biceps, it was concluded that the drive frame needed to be controlled by a triceps pull-down mechanism. Two triceps ropes were installed to raise and lower the objects. In testing the usability of the apparatus, we were able to allow a female to perform the testing procedure using the triceps ropes, and she was able to easily lower and raise the objects.

The interface of the operator and the apparatus is very self explanatory, but an instructional video and manual was produced to explain the entire process from setup to disassembly. The operation of the apparatus is very simple. The objects are easily attached using spring clips.

SafetySafety is the utmost concern of the aquarium

and team. For the apparatus to enter the aquarium, it had to pass an inspection by whale trainers. Nothing that could corrode may enter the water and all objects must be sealed to ensure that there are no spills.

The team was also required to address operator safety. No sharp edges were allowed. End caps were used to finish exposed extrusion ends on the frame. Spring clips were attached to a securing cable and installed as a secondary locking mechanism for the drive frame. This cable is used when the drive frame is not loaded down by the object frame. This ensures that the frame does not rise unexpectedly.

RESULTS AND DISCUSSION

The final product produced in this project, namely the apparatus and its accompanying objects, were a success. While it is true that the apparatus will likely not be maintenance free for 24 months, and there are still several incomplete sets of objects, it can be said that, given the time, resources, and limited on-site testing opportunities granted to the team, that an

excellent job was done of meeting the requirements. Each of the needs described in the NEEDS section of this paper were met, as evidenced by the approval of the apparatus for use at Mystic Aquarium. Several object sets are still pending approval. The technical specifications shown in Table 1 were also met.

CONCLUSIONS AND RECOMMENDATIONS

In conclusion, the VAOR apparatus project was largely a success. After 2 quarters of design and construction, a completed, functioning apparatus has been produced and approved for use. In addition, the majority of the 84 requested objects have been produced as well. Those not produced result from a lack of options, pending approvals from aquarium personnel, and pending rebuilds.

The team succeeded in its initial design stages, as well as in its redesign following the system-level design review. In a short time, the team was able to produce a new design that met all the new needs and was approved by the aquarium. The team was successful in producing a finalized bill of materials and purchase requisitions before the start of Senior Design II. This enabled the team to get orders out very early and have the majority of the required parts on hand during week 3, long before many of the other teams. The team was able to complete the initial construction of the apparatus by week 5 with minimal design changes, and begin testing to determine potential weaknesses. This time was extremely useful as it allowed a total of 5 pool tests, each which revealed important information that led to crucial design changes. The design changes made the apparatus safer, more reliable, and easier to use. The second half of Senior Design II was not spent rushing to complete initial build tasks, but to analyze the design as built and identify possible improvements. It was unfortunate that the team was not given an opportunity to test on-site at Mystic Aquarium before Friday of week 10 of Senior Design II. As a result, there was limited time in which to make suggested modifications in preparation for the start of testing at the aquarium in the summer.

Improvements to the apparatus for future generations would include simplification of several areas of the design, which would lead to better usability and reliability. Specifically, the cable actuation of the objects works well, but is somewhat prone to tangling since there are so many wires and the wires are made of steel. If the objects could be actuated using a different material or a different method altogether, while not increasing cost or weight, this would be a good improvement. Another area for improvement is the method of interfacing between apparatus modules. The current method involves lining up mounting holes and using thumbscrews to

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attach modules together. This works well enough, but with time, this could be improved to require less careful positioning and less time turning thumbscrews. A better method would prove to be less laborious to operators as well. Finally, the complicated array of shields on the object frame makes that particular component difficult to setup, move, and disassemble. Improvements to this would reduce its weight and bulk and simplify setup, storage, and transport.

In conclusion, it should be noted that while there are always potential improvements, the VAOR apparatus team did an exceptional job of addressing the question of possible improvements before Senior Design II ended. As a result, many improvements over the initially built design have already been implemented. The quality and reliability of the final design is

evidence of the immense amount of hard work and long hours spent by the team in developing and producing this design.

ACKNOWLEDGMENTS

Senior Design Team P09011 would like to thank the following individuals for their contributions to their success: Professor John Wellin, Edward Hanzlik, Dr. Risa Robinson, Dr. Elizabeth DeBartolo, and Steve Kosciol of the Mechanical Engineering Department at the Kate Gleason College of Engineering at the Rochester Institute of Technology; Dr. Caroline DeLong of the Psychology Department at the College of Liberal Arts at R.I.T, and finally the team of veterinarians and trainers at Mystic Aquarium.

Copyright © 2009 Rochester Institute of Technology