PORTABLE OBSTACLE COURSE

Transcription

1 Multi-Disciplinary Senior Design Conference Kate Gleason College of Engineering Rochester Institute of Technology Rochester, New York Project Number: P08003 PORTABLE OBSTACLE COURSE Jared Berman / Mechanical Engineer Allison Hill / Electrical Engineer Nicolette McGeorge / Industrial & Systems Engineer Samir Mian / Computer Engineer Shadle Stewart /Mechanical Engineer ABSTRACT The primary goal of the Portable Obstacle Course project is to design, construct, and store a trackable obstacle course that rehabilitation patients of the Nazareth College Physical Therapy Clinic can use to simulate a realistic walking experience. An ideal course for rehabilitation would allow for various terrain, routes, lengths, difficulty, and obstacles. It is necessary to keep track of the placement of the various obstacles, along with surface type and orientation, used during each session. The final product is 8 trackable surface pieces, with six different types of surfaces, and 19 obstacles. Included in this paper are the design concepts, manufacturing processes, and testing results described in detail. NOMENCLATURE LED Light Emitting Diode. A semiconductor diode that emits light when conducting current and is used in electronic equipment. Momentary Micro Switch An electrical switch that allows for voltages to be high or low depending on the depression of the lever. They respond to very small movements. NIOSH National Institute for Occupational Health and Safety Obstacle Any of 19 household items that can be placed on the surface pieces to obstruct the patient s movement. Surface Piece One of eight modular components of the obstacle course, consisting of various household terrains. Trackable The ability for the system to relay information to the printer, stating where each surface piece is located and where an obstacle is placed on each surface. INTRODUCTION The physical therapy clinic at Nazareth College works with individuals who have suffered strokes and are relearning to perform everyday activities. An important part of their training is learning how to navigate an obstacle course consisting of typical items that might be found in or around a home environment. The therapists would like to have a standardized course that can be dismantled and stored when not in use, and can also be reassembled to a prior "setting" in order to track patient progress. This project has two primary challenges. The first is to develop an innovative system of maximizing the number of different surfaces, obstacles and configurations that can be set up while minimizing the storage space and setup time required. The second is Copyright 2008 Rochester Institute of Technology

2 Proceedings of the Multi-Disciplinary Senior Design Conference Page 2 to develop a means of automatically documenting the course configuration that was used during any given session, so that the therapist can easily enter it into the patient's records and retrieve it for further training; the course should be able to keep track of surface orientation and obstacle locations for each training session. In addition, compatibility with the training parallel bars is also of high priority. PROCESS Design Concepts and Generation Overview Several design concepts were considered for the layout of the obstacle course. It was determined that the best design for portability would be one where the various surfaces were separated into pieces. The final design chosen was therefore of a modular type, in which surface pieces would connect together to form the length of the course. The obstacle course consists of four of these surface pieces, each 32 inches by 42 inches in dimension, in line to form a fourteen foot long course. The best design for obstacle tracking was the simplest and least expensive of the initial concepts. To track the placement of obstacles, five holes were placed in each surface piece, in which a peg, attached to an obstacle, could be placed to depress a micro switch to signify its presence. colors for visual distraction, as well as varying difficulty. Real world experiences were simulated through the placement of specific obstacles. For instance, two curb obstacles were made, a three-inch height and six-inch height for different skill levels. Either of these curbs can be placed on the concrete surface, as well as any other surface to look more realistic. The household obstacles of books, pillows, a stuffed animal, electrical cords, a heater vent, a threshold, and two pairs of shoes were provided for realistic course variation. One of the pillows provided is also large enough for the patient to stand on, aiding in balance capabilities. A large problem for the patients interviewed was throw rugs. That is, small rugs not secured to the floor that tend to move, slide and bunch up when stepped on. The provision of obstacle throw rugs helps patients become aware of the effects when stepping on such a rug, as well as helps increase a patient s reaction time and balance. Figure 1 displays the image of the final course layout with obstacles. Obstacles and Surfaces To ensure variability in surface and obstacle types as well as difficulty, the final surfaces and obstacles chosen were ones which best met specific customer needs. Patients and physical therapists of the clinic were interviewed to help gain an understanding as to the types of surfaces and obstacles needed. In order for the course to be set up in multiple configurations, eight surface pieces were provided. Six of the eight pieces were of different terrain while the remaining two surfaces were duplicates. Since multiple skill levels were necessary to accommodate a range of patients the everyday surfaces of carpet and hardwood were chosen as the duplicated surface pieces. The customer expressed the desire for surfaces that one encounters in daily life that would pose as a challenge to patients. Simulated gravel was selected for its unevenness as well as its inconsistency when walking on it. A foam gym mat was also chosen for its characteristic instability to help patients with balance. Additionally, the customer requested a simulated ice surface on which a patient could feel the sensation of slipping without actually falling. Finally, simulated concrete was created to provide a high friction surface. Nineteen obstacles were provided for course difficulty and obstacle variability. The customer expressed the need for patients to encounter obstacles of varying Figure 1: Course Setup Storage Several storage ideas were generated, such as wall shelving and racks, however the final design was based on the necessary ease of set-up and portability of the course. All eight surface pieces are stored on a cart which can be pushed to the course set-up location. There is also available storage space on the cart for the obstacles being used for a particular course configuration. Additional obstacle storage space is provided in the form of storage bins. With this design, the entire obstacle course can be stored in the allocated area of the clinic, but has the ability to be stored elsewhere. Project P08003

3 Tracking System The main goal of the tracking system is to accurately determine what surface is placed in which order of the course and also where an obstacle is placed upon each surface. In order to accomplish these goals, throughput board circuitry and a microcontroller were implemented. Switches Several different types of switches were considered for obstacle tracking. After much deliberation it was decided that a momentary on micro switch would be the best possible solution for the types of obstacles that would be used. In addition, the micro switch had to have a long lifespan to handle the amount of use it would endure. The final factor to consider was the amount of force needed to depress the micro switch. Based on the above factors, it was decided to use a Honeywell micro lever switch that requires 50g of pressure to be depressed. Shift Registers When designing the system to track obstacle placement and surface location, it was necessary to consider how all this information was to be handled. It was determined to use a chip that would allow for multiple signals to be loaded simultaneously in the chip s temporary memory. After being loaded, the various inputs would be outputted as a string of binary signals. For this purpose the 74LS165 chip, a parallel in, serial out, shift register was determined as the best fit for the needs of the project. Microcontroller The PicKit1 microcontroller was deemed the best microcontroller for the project. It allowed for robust applications, yet at the same time is a simple enough microcontroller that it would not lead to complications when developing the software. Cost was a major factor in choosing this microcontroller as it was very economical based on the project budget. Manufacturing and Design Implementation Foundation Layers of Surface Pieces Although there are six different surfaces, and a total of eight surfaces overall, each surface piece design starts from the same overall components for construction. Each surface consists of a bottom layer of non-slip foam mat, particle board, plywood and then, depending on the corresponding surface terrain thickness, an additional foam layer. Although manufacturing of these layers varies, all four layers contain two handle holes with which the surface piece will be transported. Figure 2 is an image of the various layers within each piece. Figure 2: Surface Piece Layers The bottom layer mat is WonderMat brand foam puzzle mats. Since mats had to be ordered in one foot squares it took twelve individual pieces, along with trimming, to obtain the correct size for each surface. Also contained in this bottom layer of foam is a shallow hole cut into the top of the mat on the bottom right-hand corner to house the electronics box of that particular surface. The next layer of each surface is a one-eighth inch thick piece of particle board. In addition to cutting these boards to the correct dimensions, five obstacle holes and a hole to house the electronics box were necessary. The particle board layer functions as a protective backing for the plywood layer, to follow, which houses the electronics. The third layer of each surface, a quarter inch thick piece of plywood, is the heart of the entire surface. The plywood piece is the casing for all the electronics which includes the electronics box containing the circuit board, the wires to each switch, the switches themselves and the wires to the connector cables on either end of the surface. The plywood contains five obstacle holes, a hole for the top connector and a hole to house the electronics box, along with slots along each hole to hold the micro switches. The plywood also consists of five grooved channels on the bottom surface of the wood guiding the wires to each switch location along with a wider, main channel, that guides all wires from the electronic box to either the micro switches or top connector. Channels were cut on the bottom surface of the plywood to protect the circuitry by sandwiching it between the plywood and particle board. Due to surface piece thickness considerations, five of the surface pieces require an additional layer of foam similar to that of the bottom foam mat, but not of the same brand, or size. Since quality was not as big of a concern for an inner layer of foam mat a generic brand was purchased at a local vendor. These mats, also of the puzzle variety, were 2x2 foot squares. Four were therefore required to make one surface. These foam mats contain five obstacle holes, a hole for the top connector and a hole to house the electronics box, along with slots along each hole to hold the switches. Construction of General Pieces To build each surface multiple construction methods were necessary. Since each surface required its own circuit board, construction could not begin until a circuit board was completed, and installed in the electronics box. Once this was completed the box was placed into the cutout of the plywood piece and wiring was channeled to the proper wiring positions. At this

4 Proceedings of the Multi-Disciplinary Senior Design Conference Page 4 point the wires were soldered to each micro switch in their corresponding hole location. Once all wiring was completed the plywood and particle board were stapled together. For those surfaces that apply, the inner foam piece was glued, traction side down, on top of the plywood piece using Contact Cement. After drying, these three layers were bound, using staples, on the edges, and inside the handles, with a vinyl covering for added circuitry protection, grip and visual appeal. For those pieces not requiring the foam insert layer this process was done using only the particle board and plywood layers. The next step was to glue the bottom layer of foam mat to the particle board using Contact Cement. The final step, to be done after the surface piece was securely fastened to the top (detailed in the following section), was to attach the delrin sliders to the bottom of each surface. The bottom foam layer was cut slightly smaller than the rest of the layers to allow attachment of the delrin sliders. Each slider was securely fastened to the corners of the surface, opposite the handle locations using standard wood screws. The sliders allow for easier placement of each surface piece since the foam bottom is a non-sliding surface. cut out in the plywood with a grooved section on the bottom. The plywood was placed over the particle board and white board with the acrylic plastic between the two. The plastic slides on the white board and motion is restricted by the grooves in the plywood. A maximum slip distance of two inches was allotted for the walking direction, while one inch was allotted in the non-walking direction. The result is an ice-like surface that when walked across, results in a slipping sensation, without actually falling. The concrete surface was a piece of particle board painted with non-skid paint. This surface was screwed on using wood screws. Obstacles In order to utilize the peg-hole design for the placement and tracking of obstacles on each of the surfaces a peg must be mounted to each obstacle. The best concept that was developed for this was the use of clamping plates attached to a peg on each obstacle. The parts are assembled as shown below in Figure 3 using bolts, washers, and nuts. Construction of Individual Surface Pieces Each actual surface terrain had to be handled in a unique manner, yet all surface pieces required the five obstacle holes, two holes for connector wire and two handle holes. The wood flooring, which was made using connecting wood panels, was glued together using wood glue and then glued to the general construction using contact cement. The carpet, along with carpet padding, was screwed down using wood screws. The padding was laid down on the plywood and the carpet was placed on top and folded at the edges, similar to what is done at ones house, and then screwed down. The gym mat, which was originally three feet by six feet, had to be trimmed to dimension and then was glued to the top of the plywood layer. To simulate gravel, a rubber, pronged mat was used. A significant portion of the prongs were removed to increase walking instability. Beneath this mat, a layer of foam was added with holes removed and replaced with carpet padding. This under layer of varying density material results in an inconsistent walking surface much like actual gravel. The ice/concrete surface was the most intricate surface. This surface required a white board, particle board, plywood and clear acrylic plastic. A hole was Figure 3: Obstacle Peg Design The following is a description of each of the chosen obstacles. Shoes (4): Two different styles of shoes were purchased, a croc style sandal and a flip flop style sandal. Heater Grate: This obstacle was simulated using a 14" x 8" return vent. Rugs (4): Two throw rugs of one color without any type of backing were included along with two rugs with bright colored stripes and rubber backing. Pillows (2): A small couch style pillow, as well as a larger bed pillow were selected as pillow obstacles. The bed pillow includes a removable zippered pillow case to allow for cleaning. Curbs (2): Both 3-inch and 6-inch height curbs were simulated. They were built by gluing layers of foam onto a piece of plywood. Project P08003

5 Bundle of Wires (2): A bundle of heavy duty orange extension cord that reaches across the 32" width was included, as well as a bundle with both brown and white colored indoor extension cords. Stuffed Animal (2): A bunny was purchased and a peg was mounted onto it. For a moving obstacle a barking and flipping dog was obtained. Threshold: A wooden threshold was purchased and built to cross the width of the course. Books: A stack of three hardback books were mounted with a peg. Surface Storage Cart The surface storage cart was constructed to hold 8 surface pieces. The base for the cart was a sheet of plywood with a caster mounted on each of the four corners. Initially 2.5-inch diameter caster wheels were purchased and mounted, but it was later decided that larger wheels would enhance the cart by making it easier to push, so those were replaced with 4-inch diameter caster wheels. The rest of the cart was constructed out of 2 x 4 size lumber, all of which was assembled using wood screws. The cart was designed similar to a shopping cart, with the same handle height and maneuvering capabilities. A sheet of white marker board was fastened to the inside base of the cart to provide a smooth surface on which to slide the surface pieces. The cart was also designed to fit through a standard 30-inch wide doorway to improve portability. Figure 4 is an image of the storage cart. In order for the system to recognize the type of surface on each piece, a custom circuit board was created and embedded into the piece. The shift register has 9 inputs, A-H and a serial input, which takes information from the surface piece located before it. Inputs A-E were wired to recognize which switch was depressed and where it was located. Inputs F, G, and H were all custom coded with a binary sequence. These codes could then be matched up with the memory in the microcontroller and the information would be relayed out to a printer. The codes for each piece are shown in Table 1. Surface Binary Code Concrete 000 Dark Hardwood 001 Low Carpet 010 Gravel 011 Gym Mat 100 High Carpet 101 Ice 110 Light Hardwood 111 Table 1 :Surface Codes The other signals of the 74LS165 chip that were used are: vcc, ground, shift/load, clock, and output. These five signals were fed through each piece and hooked up to connectors on each end. The shift/load signal was used to load the binary information coming from the previous pieces. The clock signal pulsed to let one bit of information go through on each clock pulse. High Level Customer Need Verification The high level customer needs were the major focus for verifying design specifications. The tracking system, ease of use, portability and safety were of highest concern. Figure 4: Storage Cart Design Setup Time One of the most important customer needs for this project was for the obstacle course to be setup in less than five minutes and as well as disassembled in less than five minutes. In the basic design concept, the time was predicted to be less than five minutes based on the flow chart seen in Figure 5. Obstacle Storage As previously stated, the obstacle storage system consists of a series of plastic storage bins. All obstacles can be stored in these bins. For a given session, one of the bins can be used to gather the desired obstacles. Hooks were also attached to the cart to hang obstacles from. Tracking System

6 Proceedings of the Multi-Disciplinary Senior Design Conference Page 6 Surface Weight (lb) Carpet (High) 25 Carpet (Low) 26.5 Hardwood 36 Ice 37 Concrete 27 Gravel 39 Gym Mat 27.5 Table 2 :Surface Piece Weights The heaviest surface piece, gravel, was analyzed to ensure that the recommended weight limit for the given task was not exceeded. The NIOSH Lifting Equation[1] was used to compute the lifting index for the task of removing the heaviest surface piece from the center of the storage cart. Table 3 shows the resulting calculations. Table 3: NIOSH Lifting Equation Figure 5: Setup Flow Diagram This prediction and the obstacle course design were tested to ensure the specification was met. Students from this team and other senior design teams were directed to set up and disassemble the course at a reasonable pace while being timed. Set-up was simulated based on distance between storage and use locations similar to those in the actual clinic. The average male setup time was 1.7 minutes, and the average for females was 1.87 minutes. These times only include setting up the course surface pieces and placement of obstacles. Since this is well under the five minute maximum, there is adequate time remaining for setup of the future implemented tracking system. Surface Piece Weight In order for portability, the modular design was chosen. With this design, the physical therapist must lift each surface piece off of the storage cart to set up the course. Therefore, surface weight was minimized to increase ease of use as well as safety. Table 2 is a compilation of the weights of each of the surface pieces. NIOSH states that a lifting index less than three is acceptable for a given task; however some people may be at risk of injury if the value is above one. To minimize this risk it will therefore be suggested to the physical trainer that the heavier surface pieces be placed on the outside of the cart. The second portion of the task, sliding out and carrying the piece to the set-up location, is safe for all surface weights. Figure 6 depicts an image demonstrating removal of a surface piece from the cart. Figure 6: Surface Piece Removal Switch Testing When making use of the switches in the actual design of the project, it was necessary to check the appropriate functionality of each switch. To verify functionality, each switch was wired in series with an LED on a breadboard. Each switch was then opened or closed and the LED would light up appropriately; the Project P08003

7 LED was on when switch was depressed and the LED was off when switch was not engaged. Shift Register Testing Each of the 74LS165 chips needed to be tested to verify the correct functionality of each chip. On a breadboard one chip was set up with static inputs. A clock signal was setup and routed to the appropriate input on the chip. The output of the chip was then routed to an LED. Once the breadboard was powered and the clock signal was activated, the LED-output was noted. The LED would be on or off depending on the signal that was being shifted to the output port. After having one chip wired and connected appropriately it was possible to remove one chip and place another one for verification. J.J. Mowder-Tinney and Lyndsey from Nazareth s Physical Therapy Clinic. We hope the project has met all of their expectations. Dr. Debartolo, our guide, thank you for all the support throughout the two quarters. Dr. Reddy for his countless innovative ideas. Dr. Marshall for his expertise After each of the circuit boards was constructed, it was tested on this prototype board to ensure proper functionality. It was again tested, using the same setup, after being sandwiched into the pieces. CONCLUSIONS AND RECOMMENDATIONS The finished project yielded eight surfaces, two being duplicates, and 19 total obstacles. A cart, which was redesigned from its initial concept, along with a storage bin, will also be provided. All surface pieces contain embedded circuitry including the through-put boards, micro switches and wiring. The current product does not currently have controlled feedback for the physical therapist, but a tracking sheet, with copies, will be included with the delivered product. The obstacle course and cart are fully functional without the automated tracking system and can still be used for patient training sessions. For future work an independent study is being asked to continue work with our current, or possibly new, microcontroller to acquire the necessary feedback from the surface pieces. Also, once this feedback is accomplished the output will need to be transferred to a printer for the physical therapist. REFERENCES [1]The Revised Lifting Equation. (1994, January). Applications Manual for the Revised NIOSH Lifting Equation. Retrieved May 12, 2008, from National Institute for Occupational Health and Safety Web site: niosh/docs/94-110/ ACKNOWLEDGMENTS For the duration of this project there were many people without whom we would not have attained the success we have. From conceptualizing, designing, and testing these people were pivotal to our team s performance:

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