Proceedings of the 2005/2006 Spring

Multi-Disciplinary Engineering Design Conference Kate Gleason College of Engineering

Rochester Institute of Technology Rochester, New York 14623

May 12,2006

Copyright © 2006-06209 Sensory Awareness Trail

Project Number: 06209

SENSORY AWARENESS TRAIL

Richard Adams – Team Leader,

Mechanical Engineer Chiedu Monu,

Electrical Engineer

Tony Wong, Mechanical Engineer

Luke Hogan, Mechanical Engineer

Timothy Mugwanya Electrical Engineer

ABSTRACT This paper walks the reader through the various processes in the design development of sensory stimulation products for the developmentally challenged customers of the Everybody Rides program in Newark, NY. The main objective of the project was to produce a weather resistant audio narrative system prototype that runs on regenerative or renewable power, develop a plan for a timber bridge which can withstand loading from the horses and riders, and construct other various recreational modules which provide interactive visual, audio, and motor skill stimulation. This paper illustrates the overall goals of the effort, developed designs, and analysis for the devices. NOMENCLATURE Hippotherapy – (from the Greek "hippo" meaning "horse") is a physical therapy that utilizes the natural movement of the horse to help riders regain physical strength, mobility, and coordination. The similarity between a horse's pelvic movements at a walk and the movement of a normal human pelvis enables the rider to physically learn or relearn skills and movements that may have been lost or compromised [D]. Developmentally disabilities – variety of conditions that become apparent during childhood and cause mental or physical limitation. These conditions include autism, cerebral palsy, epilepsy, mental retardation, and other neurological impairments [T]. Visually Impaired – people who are incapable of sight; i.e. blind.

PVC – With its good chemical and corrosion resistance, PVC (polyvinyl chloride) is the most widely used vinyl plastic [R]. Electrical generator – a device that produces electrical energy from mechanical energy (for ex. Dynamo) [S]. Dynamo – uses electromagnetic principles to convert mechanical rotation into an alternating electric current. Commonly found in bicycle and battery charging applications [S]. Decibel (dB) – a “dimensionless” measurement (like percent) used in a widely in acoustics, physics and electronics but usually measures the loudness of sound [U].

INTRODUCTION

Since its inception in 1984, our nonprofit sponsor, Everybody Rides, has served well over 400 riders with developmental disabilities annually. Located at a farm in Newark, New York, Everybody Rides is an accredited member of the North American Riding for the Handicapped Association [E] with a team of professionally trained staff and volunteers whose main goal is to serve and treat individuals with developmental disabilities through therapeutic riding [D]. Therapeutic riding consists of a physical therapist and a horseback riding program instructor collaborating to provide physical exercises and horseback riding guidance for trail users with disabilities. This has proven to be beneficial the riders by increasing their muscle tone, motor skills, and emotional well-being through a physical therapy practiced called Hippotherapy. To further enhance the experience, the sponsor

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has asked that the existing horseback trail be converted to a sensory trail (or trail including stations that provide sensory stimulus to its users). By concentrating the riders’ effort on the nature around them, the therapeutic riding will further relax and educate the clients physically and mentally. The team has worked with the customer to create the most suitable designs to accomplish these goals.

DESIGN REQUIREMENTS

Extensive research on similar sensory trails currently in existence along with meeting the customers at Everybody Rides, helped determine the needs of the project. These needs were then used to develop the following design requirements:

Mechanical

All projects require maintenance less than 3 times annually

Electronics are enclosed in no less than one layer of weatherproofing

All electronic enclosures are screwed shut

All wood is pressure treated and/or sealed with water repellant

Electrical

No more than 300mA on any circuits

All power sources are renewable/rechargeable

Aesthetics

All installed objects are off of the beaten path in locations agreed upon by Everybody Rides

All projects external parts are colors or materials found in nature

Activity

1/3 of devices installed stimulate the motor skills of participants

Sense of smell is stimulated at least once

Sense of touch is stimulated at least once

Sense of sight is stimulated beyond the normal level of the trail at least once

Safety

Any edges on devices are no sharper than anything found in nature

Load bearing objects have a factor of safety of 2 or higher

No flashing lights are used

Decibel levels of installed devices do not exceed 85

General

Plan includes the top 4 ideas not installed on the trail as agreed upon by Everybody Rides

DESIGN CONCEPTUALIZATION

After reviewing the researched information, ideas and concepts were formulated for the sensory trail. A common sensory stimulus that was found on various locations along the trails was the use of signs to explain to participants the unique or important aspects of nature nearby [F-I]. This idea was further developed to implement the sense of sound on the trail by designing electrically powered audio clips to perform the same function of the signs. The design of these audio devices was divided into two sensory stations: (1) narrative audio boxes and (2) animal silhouettes. Both devices will play audio clips the only difference is the animal silhouettes will be designed to output clips that mimic actual animal sounds projected by its respective animal silhouette. Therefore the clients will play a ‘guessing game’ where they will have to guess which clip matches the correct silhouette as part of their learning experience while at this station. Meanwhile at the narrative audio box station, the clients’ therapist will turn a dynamo generator handle to charge up the audio circuit inside of a PVC enclosure. Once the circuit has reached a nominal value of 5 volts, the PLAYBACK button on the box will be pressed and the audio box will play a 20-second informative message educating the clients about the plant life in their surrounding natural environment.

A common feature of similar sensory trails is chimes that users are encouraged to strike which cause them to emit different melodic sounds. Most chimes currently in use are intended only for walkers of the trail [F-I]. This idea was upgraded to include horseback riders as well by enlarging the chimes to a height of eight feet. To further the visual stimulation of such a large structure, bamboo was determined to be a pleasant, exotic, and natural material that would be ideal for this application.

A major request by the customer was to attach baskets to trees along the trail. These baskets would then be filled with pine cones for horseback riders to carry from one basket to another. A major benefit of adding these baskets is that the game that results requires a large reliance on motor skills. Additionally, the sense of touch would be stimulated by handling the pine cones. The customers also stated that, by completing this game, the trail participants would achieve a sense of accomplishment. Finally, some of the clients on the trail are

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athletes that compete in the Special Olympics and this station will provide the necessary training in hand-eye coordination.

Another request that the customers made was to incorporate the sound of running water at the small pond adjacent to the horseback trail. This was done simply by installing a solar-powered fountain on the pond. The participants at this station will be inclusive of any visually-impaired walking clients for the sound of running water will give them something tangible to associate this part of the trail with and educate them on the aural aspects of water.

DESIGN DETAILS

I. Narrative Audio Boxes and Animal Silhouettes

Figure 1: Typical position user position for narrative audio box station.

These designs employed the use of a dynamo (hand-crank) generator as a renewable power source. Both the narrative audio boxes and the animal silhouettes involved this same technology for proper operation. It was the most cost effective option as far as renewable power sources are concerned. Other options included solar power, radio frequency (RF) technology (transmitter and receiver) and wind power. After close review, these options were discarded during the concept development stage for the following reasons: (a) the location of these stations is in heavily shaded areas where an abundance of sunlight is rare; (b) using RF technology on the trail would be too expensive; and (c) wind turbines require open landscape such as farms, mountain ridges, and atop cliff faces to because the wind speeds are supposedly higher in those areas.

The intended function of the narrative boxes/animal silhouettes is to educate potential riders/clients on their natural surroundings during their therapeutic sessions. With the narrative audio boxes, the user will approach the station facing the front of the audio box as displayed in Fig. 1. To operate the box, the user must first open the wooden hinge door (not shown in Fig. 1) to access the controls inside the wooden encasing. Next, the user will grab the hand crank generator handle located to the right of the PVC enclosure and wind it in a circular motion (in a fish-reeling motion). After approximately two minutes of consistent winding, the user will stop and press the red PLAYBACK button located in the top right hand corner of the enclosure. If these instructions are followed correctly, a pre-recorded informative message will play for a maximum time period of 20 seconds. This message will highlight something unique surrounding its location such as plant life, unusual smells, etc. Fig. 2 below displays a close-up external

view of the narrative audio box once the hinge door has been opened. The entire box will be mounted to a post for support. The wooden encasing around it including the hinge door serves the purpose of protecting the integrity of the internal circuitry from harsh weather conditions. These boxes will be placed in various locations across the 104-acre trail.

Figure 2: External view of the audio box.

The assembly of the audio boxes began with the internal electrical components. A recording module was connected to a power audio amplifier with a speaker for clearer sound. The amplifier was connected to the main power source which was the hand crank generator. A larger PLAYBACK button was soldered on top of the recording module. Once the electrical audio circuit was fully assembled, it was placed into a PVC enclosure. The only exposed components from the circuit are the speaker, hand-crank generator handle and PLAYBACK button. The enclosure was then screwed into a pressure-treated wooden encasing that is mounted to a post. Lastly, the enclosure is sealed with a hinge door covering the front of the audio box.

The internal components of the audio box include a combined circuit of a 5V-record/playback module and a power audio amplifier. This combination was powered by the hand crank generator and the audio clip was then outputted through a 2-Watt, 8-ohm speaker.

The hand crank generator produces AC voltage initially so it was connected to a DB101 rectifier chip. The rectifier converted the generator’s AC voltage to DC. This DC voltage was regulated at approximately 5 V by a LM340 regulator chip. In this process, the current drawn from the generator through

Playback Button

Speaker

Dynamo Generator Handle

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the rectifier and regulator was measured by a digital multimeter.

The following table was created from the results gathered during this experiment.

ROUT (Ohms) VOUT (V) IOUT (A) POUT (W)

10 3.63 0.36 1.3068

500 4.86 0.152 0.73872

1.00E+03 5.054 5.05E-03 0.02552

Table 1: Hardware results for dynamo generator. It can be seen that as the output voltage increased, the output current decreased as a result of the regulator’s limitation on output power. Ultimately, a higher equivalent resistance is desired to ensure that lower levels of power will reach the 2-Watt speaker. This pattern is also displayed in Fig. 3.

I-V Plot

y = -0.2207x + 1.1688

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0 1 2 3 4 5 6

Voltage (V)

Cu

rren

t (A

)

Figure 3: Output voltage vs. current plot of dynamo

As for the recording module, its operating specifications were typically 5V and 25mA which was well within the desired specifications of the generator.

Figure 4: Record/Playback module

The animal silhouettes station utilizes the same technology as the narrative audio boxes except it combines the aural aspect with a visible component of the life-size animal silhouette template. The animals portrayed in the silhouette templates are ducks, turkeys and bears.

II. Bamboo Chimes

Figure 5: Typical user position when operating bamboo

At the trail’s entrance riders and walkers will approach the bamboo structure. A basket containing sticks from the trail is mounted to the side of one of the 4”x4” posts. By removing a stick and striking the various lengths of bamboo different melodies will be produced. This structure stands 8 feet high with the support posts extending below the frost level of the ground (four feet) [K]. The three pieces of lumber used for this structure are pressure treated and, along with the bamboo, have been coated with a water-repellant. Poured concrete assists in holding the structure in place below the surface.

Figure 6: Bamboo Structure and Assembly

The bamboo is mounted to a 2”x4” that spans 53” across the posts. A bolt enters one side of the bamboo where it goes through two links of a chain and then out the other side of the bamboo. This chain is suspended by an eyebolt that is secured to the 2”x4”

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Figure 7: Pine Cone Bucket

Three wicker baskets have been fixed to trees along the trail. Screws are used to secure them at a height of approximately 4 feet above ground. This gives participants on horseback the ability to reach the baskets.

Figure 8: Solar Powered Fountain

This 10 inch diameter, lily pad shaped fountain is installed approximately 5 feet from the pond’s shore. Multiple rocks are bound together in a net that is tied shut by a fishing line. This line is then secured to a hose that is on the bottom of the fountain. The line is long enough to allow the fountain a certain degree of mobility.

ANALYSIS

Narrative Audio Boxes and Animal Silhouettes

The audio box uses a recording module connected in parallel with a power amplifier; they can both operate at 5 volts. However, the maximum allowable voltage of the recording module is 6 volts. Due to the fact that, the audio box will be power by a 9 volt source, a 5 volt voltage regulator will be used in series with the recording module. At the out put of the amplifier will be a high efficiency 3 inch speaker with maximum power of 2 watts. These audio boxes will be used for the narrative Audio Box Station and the Animal Silhouette Station.

The ultimate goal of the electrical circuitry is to power an audio device with the use of a rechargeable 9 volt battery. A rechargeable battery is used because a hand crank generator is to be employed in the future design of the circuitry. This will allow the batteries to be recharged while it is still in the unit. Energizer® Rechargeable™ batteries offer a good environmental choice for this device. They are made with nickel metal hydride (NiMH) which is safer for the

environment than nickel cadmium, and they can be recharged as many as 1,000 times. The battery is rated to about 150 milliamp-hours; milliamp-hour means how much current a battery will discharge over a period of one hour. The recording module has a play back time of 20 seconds; therefore, this device can be conservatively played 180 times before it needs to be recharged.

Bamboo Chimes

To ensure the safety of the users when operating the bamboo chimes, stress analysis was performed on the wooden support structure and the bamboo itself.

The 3” diameter moso bamboo used weighs approximately 1lb for every foot of length. This information was used to apply the 7 forces acting on the 2”x4” cross member.

Figure 9: Stress Analysis of Cross Beam

The maximum Von Mises stress produced is 126.7 psi. Comparing this to the modulus of rupture for eastern hemlock, 8,774 psi [A], the factor of safety is determined to be 69.6.

Similar FEA analysis was performed to verify the safety of the eyebolt-pin connection on each bamboo stick. Due to limited information on strength properties of bamboo, a conservative analysis approach was to use the properties of Balsa wood [A] to predict the loading behavior and the resulting stresses. Since the bamboo’s strength is roughly nine times higher than that of the Balsa wood, this implies that the actual factor of safety of this component is considerably higher than that of the following Von Mises stress plot, which is 19.6:

Figure 10: Stress Analysis of Bamboo

EXPERIMENTATION AND DATA INTERPRETATION

FUTURE IDEAS PACKET

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A packet that includes designs of other concepts will be given to Everybody Rides. These concepts were developed by using the needs assessment and design requirements as guidelines. The ideas can be implemented by future design or volunteer groups. The following are the concepts in the “Future Ideas Packet”

Figure 11: Squirrel Chase station

This station challenges the motor skills of the trail users. A participant pulls on a rope that goes over a pulley and is then fastened to the squirrel. This causes the squirrel to travel up the rods that it is guided by.

Figure 12: Woodpecker station

Once again, the station shown above is a device that utilizes motor skills. The user would pull a rope that is connected to an eye bolt on the body of wooden woodpecker, which in terms causes the woodpecker to pivot and strike the tree that it is attached to.

Figure 13: Hand Powered Animals station

A turn of the hand crank will cause the mechanical animals to bob up and down, due to the motion of the rotating cams. This would enhance the motor skills of the trail user.

Figure 14: Water Wheel station

The trail participant will cause water to splash on the surface of a pond by turning the hand crank. Inside the gear boxes are bevel gears which allows the transfer of rotation motion to the water wheel.

Figure 15: Trail Bridge station

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The trail bridge provides a valuable scenic addition to the trail. Trail users will enjoy the soothing experience while crossing the bridge over a small trail creek. The hoof sound of a horse walking across the bridge further enhances the tranquility and nature elements of the trail.

To ensure that all bridge components can withstand the loading, a Finite Element Analysis was performed using ANSYS software. The strength properties of the wood material were adjusted using a given table [A] of established data at 12% moisture content to account for the maximum wood moisture content of 20.9%, which occurs in the month September [J].

Strength Property Adjustment Equation

( 2 1)

2 1 1100

M MC

P P

; (1)

P2 and P1 are the strength properties at 20.9% and 12% moisture level, respectively. Similarly, M2 and M1 are the moisture contents at 20.9% and 12% moisture level, respectively. C is a constant specific to the strength property under study and is listed on [B]

The following table shows the modified strength properties at 20.9% moisture content:

12% (P1) 20.9% (P2)

Specific Gravity

0.4 0.3965

Modulus of Rupture

8900 psi 8774 psi

Modulus of Elasticity

1200 ksi 1177 ksi

Max Crushing Strength (Parallel)

5410 psi 5324 psi

Compression Perpendicular at Proportional

Limit

650 psi 642 psi

Shear Strength Parallel to

Grain 1060 psi 1051 psi

Table 2: Adjusted strength properties

Column buckling and finite element stress analysis were performed, using modified wood strength properties [A] as shown above, on various bridge components and loading conditions. As shown in the critical design report, factors of safety for all bridge components and loading cases are at least 2.

FUTURE WORK

Charging Circuit

A charging circuit needs to be employed in the audio device to ease its maintenance. The hand crank generator is a commercial device that is utilized as part of this charging circuit. A 9 volt rechargeable battery will be charged by using a rectifier at the output of the hand crank. The rectifier will convert the AC voltage into DC voltage. Then a resistor and a diode will be used. The resistor helps maintain a constant steady current that will not over charge the battery and the diode limits the amount of charge that is allowed to enter the battery. Fig. 17 displays a block diagram describing the operation of the audio circuit with the generator serving as the input and the speaker as the output.

Generator

with

Rectifier

Charging

Circuit

Record/

Playback

Module

Amplifier

Speaker

Figure 16: Audio Circuit Block Diagram

ACKNOWLEDGMENTS The team would like to thank Dr. Elizabeth DeBartolo and Dr. Daniel Phillips for their mentoring roles. Special thanks also go to the employees and volunteers associated with Everybody Rides. These members include Sue Epstein, Lisa Williams, Ron Mamroe, Mark DeCracker, and Jo Anderson. Finally, the team would like to thank Jeana Sansocie, the Industrial and Systems Engineering student that provided our team with a project readiness package.

REFERENCES [A] Wood Handbook - Wood as an Engineering Material. U.S. Department of Agriculture. Online version available at: http://www.knovel.com/knovel2/Toc.jsp?BookID=460&VerticalID=0

[B] Avallone, E.A.; Baumeister, T., III (1996). Marks' Standard Handbook for Mechanical Engineers (10th Edition). McGraw-Hill. Online version available at: http://www.knovel.com/knovel2/Toc.jsp?BookID=346&VerticalID=0 [C] Adams, Cassandra; Elizabeth, Lynne. (2000). Alternative Construction: Contemporary Natural Building Methods. John Wiley & Sons, Inc [D] everybody-rides.org [E] www.NARHA.org

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[F] http://www.sensorytrust.org.uk/information/factsheets/sensory_ip.html [G] http://geoffandwen.com/blind/newsarticle.asp?u_id=6307 [H] http://www.townfield.doncaster.sch.uk/pages/trips/earthcentre/senses.htm [I] http://www.noahsarkgardens.co.uk/Articles/SensoryGarden.htm [J] http://www.weather.com [K] http://www.dot.gov [L] http://www.electronics123.com/s.nl/it.A/id.499/.f?sc=14&category=2

[M] http://electronics.howstuffworks.com/battery9.htm

[N] http://www.energizer.com

[O] http://www.maxim-ic.com/appnotes.cfm/appnote_number3501

[P] http://www.web-ee.com/schematics/battery%20charger/charger.htm

[Q] http://hyperphysics.phy-astr.gsu.edu/hbase/electric/shock.html [R] McMaster-Carr [Online document] Available at HTTP [2006 May 11]: http://www.mcmaster.com/ [S] “Electrical Generator” Wikipedia, The Free Encyclopedia. [Online document] Available at HTTP [2006 May 11]: http://en.wikipedia.org/wiki/Electrical_generator [T] New York State Office of Metal Retardation and Developmental Disabilities (OMRDD) [Online document] Available at HTTP [2006 May 11]: http://www.omr.state.ny.us/document/hp_faqsdd.jsp [U] “Decibel” Wikipedia, The Free Encyclopedia. [Online document] Available at HTTP [2006 May 11]: http://en.wikipedia.org/wiki/Decibel