DESIGN OF A SEATED BALANCE TRAINING DEVICE
Contents
1. Figure 12 Final Assembled Tower Wiring harnesses were designed to organize the inside of the tower using zip ties and electrical wire To reduce interference of the wire conducting the capacitance chip to the aluminum plates the wires were wired in separate harnesses The two solderable breadboards were placed on different sides to keep wires clean and organized and the MSP430 was designed so that the wires out would be out of the way hinged door for easy access to the JTAG port and the battery pack To simplify the wiring within the tower a color coded system was designed Dark red was used for components requiring 3 3V light red was used for 5V components and the color of the wires going from the LED s corresponds with the color the LED emits Testing A test plan was developed to ensure the engineering specifications were met and the device would perform to meet customer expectations The mechanical testing included ensuring the correct height of device fit the patient The device needed withstand a tip test verification of the calculated push forces which intern would provide the force needed to move the device The electrical testing included optical visibility of the LED s and testing the sensitivity of the capacitance buttons The software testing included validating the game response time was sufficient for the customers needs and that the program is outputting the correct average number of levels completed2. LED s were chosen as opposed to traditional single color LED s to limit the number of wires in the tower As displayed in Figure 9 blue will illuminate indicating the target green will indicate that the correct target has been touched and red will indicate either that the incorrect target has been activated or that time has expired Blue Green Red Figure 9 LED Illuminations Auditory Feedback A PC Beep speaker was added to the device to give the patient and physical therapist auditory feedback If the physical therapist is holding the patient and not watching the colors they will identify when the patient has correctly or incorrectly hit the target The program was designed so that it will beep once only if the target is successfully hit Measurement System In order to measure the distance from the patient to the tower four methods were considered 1 Infrared Sensor 2 Sonar Sensor 3 Standard Mechanical Tape Measure 4 Electric Tape measure Each method was tested and the needs of the customers and functionality were considered Ideally a precise output from a sensor or electronic tape measure would best fit the customer needs However the infrared and sonar sensor did not consistently identify the same point on the patient which would make replication difficult Further research should be done with background noise and having the patient holds an object that could be measured A standard tape measure was chosen t
3. MSP430 to quickly understand port I O and ISR scheduling Future developers will appreciate the time and effort spent on this milestone In phase III a working prototype presented and verification of the code was complete The game was designed in the final phase Phase IV Game Design For the initial revision two games were included Random Touch and Timed Touch Random touch selects one of the previously enabled targets lights that target in blue and gives the patient a variable amount of time to reach and press the target If successful a chime plays and the LED rows will illuminate green Unsuccessful yields red LEDs The second game Timed Touch shows each target in order from top to bottom and records the amount of time taken to reach each target Project P10005 Tower Transportation To meet the last customer need easily stored and portable a transportation storage cart was designed This cart was constructed using the excess PVC and was designed to hold the two towers and two bases It has foam along the top protecting the tower from the cart and making the towers sit flush against the cart Two separate adjustable straps were added to ensure the towers do not move as well as three inch wheels to allow the cart to be pushed easily The cart measures 2 by 1 which allows for the cart to be stored easily within the clinic Figure 11 Transportation Cart Tower Assembly
4. Once the tower was completed system testing was completed that verified the time to understand program time to disassemble the device configuration time of the game as well as usability of the user s manual and screen output data sheet RESULTS AND DISCUSSION Table 5 shows the results of the final product and the actual values of each engineering specification These values were results of the testing completed on each component as well as some of the subsystems Table 4 Final Engineering Specifications Marginal Ideal Max tilt angle before falls mins Baton Sensiviy pfu 1625__ Negligible Average of levels complete oe Nn N IS N gt fines a Pure dav om torepiasd hse howe be All of the engineering metrics were met with the exception of the percentage of replacement parts The height of the device is 1 5 taller than ideal but this height includes the 2 base and the customer was still satisfied with the end result CONCLUSIONS AND FURTHER RESEARCH Proceedings of the Multi Disciplinary Senior Design Conference Page 8 In conclusion the two physical tower structures were completed The main tower is fully functional with wiring harnesses complete and organized The two games Random Timed Touch and Timed Touch have been programmed to illuminate the buttons and give feedback on success and failures as well as auditory feedback upon completion The screen is programmed to give th
5. Red Green Blue Light Emitting Diode A semiconductor diode emitting light when conducting current in red green and blue Andy Caola Computer Engineer Jeff Hansley Electrical Engineer Luke Holsen Mechanical Engineer NIOSH National Institute for Occupational Health and Safety 3DSSPP 3D Static Strength Predication Program which provides requirements for tasks such as lifts presses pushes and pulls JTAG Joint Test Action Group Olimex MSP430 JTAG ISO Programmer IEEE Standard 1149 1 BACKGROUND This project aims to develop a balance training device to be used by the physical therapy teaching clinic at Nazareth College The system will train clients with disabilities that require them to use a wheelchair The device specifically can be used for clients with spinal cord injuries multiple sclerosis MS lower extremity amputation or for anyone confined to a wheel chair At the clinic the physical therapy students are taught to use various forms of balance training devices to assess patient ability to move in certain planes and reach in movements similar to daily tasks Research shows that assessing a patient s ability to balance can be directly related to their chances of falling The clinic uses training to put clients in positions that could potentially make them fall so they can learn how to correct the movement on their own Copyright 2010 Rochester Institute of Technology Proceedings of the Multi Dis
6. WARY ENG ow Vey Sy MU Up S mwN Senior Design Multi Disciplinary Senior Design Conference Kate Gleason College of Engineering Rochester Institute of Technology Rochester New York 14623 Project Number P10005 DESIGN OF A SEATED BALANCE TRAINING DEVICE Rochelle Perry Industrial Engineer Team Lead Michael Davies Mechanical Engineer ABSTRACT The goal of this project is to develop a balance training rehabilitation device for clients of the Physical Therapy Clinic at Nazareth College Current methods of balance training include a standing Balance Master device and a highly subjective method of asking the patient to reach to a target held by the therapist This new device has been designed to close the gap between these methods by providing an objective measure of reaching ability for primarily wheelchair bound individuals It will give the patient illuminated targets at challenging distances and patterns of reach and it will be easy to use for both the therapist and the client To accomplish the goals of this project two structures were built for the clients to reach to equipped with capacitive buttons that will require no force from the patient to activate and a game is in place to illuminate the buttons and give feedback to the physical therapist The outer shell of the second tower is completed and plans are in place for future wiring and game design integrating the two towers NOMENCLATURE RGB LED
7. William Brewer RIT Medical Sciences Dr Matthew Marshall RIT Industrial Engineering Professor Rickel RIT Industrial Design Dr Daniel Phillips RIT Electrical Engineering Dr Pratapa Reddy RIT Computer Engineering Development Rob Kraynik RIT Mechanical Engineering Shop Project P10005
8. and compute the RWL s RWL LC HM VM DM AM FM CM Origin RWL 51 0 83 1 0 88 1 1 0 9 33 66 Destination RWL 51 0 83 1 0 88 1 1 0 9 33 66 Compute the LIFTING INDEX weight RWL Origin Lifting Index 2 Destination Lifting Index 32 Figure 6 NIOSH analysis of lifting task 33 66 0 95068 lt 1 Not Large Risk given assumptions 33 66 0 95068 lt 1 Not Large Risk given assumptions The lift index was calculated to be below 1 which means that given the assumptions and correct posture lifting the tower is not a dangerous operation The base is made out of 100 recycled rubber It is 2 thick and 20 long and weighs 20lbs this provides enough weight to stabilize the tower The rubber was chosen as an added safety precaution if a patent falls before the physical therapist can catch them the rubber dampers the fall rather than having a hard unsafe object to protrude out of the tower It also covers any sharp corners along the edge of the Aluminum and PVC The recycled typically used for road cones will be very durable and hold up to repeated use Each base was cut into two pieces and set around the base of one of the towers As demonstrated in Figure 7 the individual pieces of the base sits on a flange protruding from the tower giving the tower increased stability and each side onto rods allowing for simple assembly of the device Figure 7 Modular Base Designs Object Touch Capacitance buttons were determined to be the
9. ciplinary Senior Design Conference Page 2 In order to assess the need for balance training at the clinic an assessment was made of the current methods of balance training by the physical therapists PT and clients with various disabilities Table 1 contains the advantages and disadvantages to the benchmark products used at the clinic Table 1 Benchmark Balance Training Devices Device Advantages Disadvantages No objective measure of PT Hold Simple to use Device No set up patient progress No storage space Boring SMART Objective measure of Standing only Balance patient progress Difficult to use Master 1 Frustrates patient Nintendo Wii l Stimulating Game Nintendo does not Fit 2 Too much for clients support Physical with low cognitive Therapy ability Difficult to determine what actually training To fill the gaps at the Physical therapy clinic there was a need for a device for seated balance training that was simple to use and visually stimulating to the patient The unit would be designed such that once it is set up the therapist can focus on the patient rather than the object they need to reach Being able to quantify the patient s ability to balance will help track the patient s progress throughout their therapy Sessions The completed device as demonstrated by a student can be seen in Figure 1 Figure 1 Final Tower Design PROCESS Customer Needs In order to begin the design process the custo
10. design which was also constructed and shown to clients at the clinic Project P10005 Figure 2 Tri Fold Target Design After building a mock up of the device out of cardboard and speaking with clients about its functionality it was determined that the design missed four very important customer needs It was too large it would take up too much space in the clinic it wouldn t be portable and it was very overwhelming for the patient to sit in front of Through more brainstorming and combining components of some ideas a modular tower design was developed and selected A selection matrix was used to decide on this design using the customer needs as criteria As seen in Figure 3 the concept was designed to have a minimum of four individual posts that would cut back on space and not be overwhelming to the patient Each post could have three light up buttons and be individually wired into a central USB The posts would be easily moveable to allow for simple adjustment and easy storage Figure 3 Initial Tower Design After demonstrating some preliminary designs with customers and subject matter experts it was noted that some clients may have limited strength to push buttons and the few feet between each tower would not track the incremental change at each physical therapy session As a result it was suggested to have a tower with one continuous button tower using capacitance buttons Figure 4 shows the modified tower desi
11. e AR Embedded Workbench setting up variables at runtime was straightforward By providing the ability to pinpoint error locations hardware software other we could quickly address any issues that arose Port identification for the MSP430F1611 was provided in the datasheet specific to the DZ1611 model All ports were verified after an early mix up in the TI documentation which was later submitted and approved in their most recent errata release By identifying the addressing properties of the MSP430 setting up ISR interrupts and accurately locating debug errors was much easier Input and Output testing took the majority of or debug time mainly due to a non shielded wire issue After using technologies provided to us by members of various other MSD teams to verify the issue wire was rerun using a shielded option and I O test harness Upon successful completion I O testing was marked as continued development in order for us to continually debug at each port or breadboard modification Phase II consisted of selecting a compiler and in code documentation The IAR Embedded Workbench provided by TI proved very useful Although code space was at a minimum due to the imposed 4kB limits the provided tools and compiler proved themselves useful time after time Additionally the comprehensive documentation provided by TI was used throughout the project in code documentation was completed to allow even for a first time user of the
12. e physical therapist readings at the end of the game Due to extensive testing required on the towers only the outer shell of the second tower is completed and plans are in place for future wiring and game design integrating the two towers One concern of the customer that was not met was providing low cost repairs Due to the technology chosen it was not feasible for replacement parts to be provided While extra strands of LED s were soldered and left behind it wouldn t be easily replaced by the clinic Also even though the wiring is color coded it would be difficult for any fixes to be made by the clinic Future research could make the components modular and easily replaced and fixed While the scope of this project did include two tower completion and a device to measure the distance from the device to the patient both require further research to validate the technology A tape measure will be provided to measure the distance from the device to the patient until the sonar sensor measurement system can be implemented Documentation has been left behind within the program to further develop the wireless communication between the two towers and develop games that integrate both towers Further research can be done to allow data to be transmitted to a computer and track the patient s progress from session to session storing the patient s data for research purposes REFERENCES 1 N I Inc 2009 SMART Balance Master lt
13. fe region was determined to be between 32 and 39 lifting from the storage device to the floor Figure 5 Modified Tower Design Table 3 Tower Force Calculations Location h Required Force F d Top of Tower 60 6 6 lbs Middle of Tower 30 12 45 11 77 lbs Base of Tower 10 50 43 Ibs Base As noted in Table 3 the tower will theoretically come back to its vertical position until it is pushed past 24 5 which correlates to a 25 displacement in the horizontal direction at the top of the tower The maximum distance a typical patient can push is 12 which was calculated using 3DSSPP and which is significantly less than the 24 required to tip To ensure the safety of the PT while moving the device an analysis was done to see if lifting the tower 321b would be damaging to the PT if they had to perform the task repeatedly It was assumed that a cart would be made holds the towers so the maximum lift would be from the cart to the floor It was also assumed as a worst case scenario that there were no handles and that the PT would lift the device a maximum of 4 times per shift Figure 6 shows the NIOSH lifting equation 3 that was used to determine the lifting index Measure and record task variables Vertical gi Frequency R Duration Object Dest Distance in Origin Destination lifts min HRS Coupling C L Avg L Aavg H H vV D F 30 0 2 0 Poor Determine the multipliers
14. gn with multicolor LED lights between capacitance buttons on the tower The lights would light up in different colors based on the ability for the patient to reach buttons on the tower Figure 4 Modified Tower Design The selected design entailed a multiple tower design acting as targets for the clients to reach to The towers would illuminate in various patterns that challenge and train the patient s balance Ideally the customer wanted two towers to require the patient to reach from side to side The scope of this project included implementing and testing the technology behind one tower which could eventually be turned into a multiple tower game Each tower will eventually be remotely connected to the main tower Analysis Tower Structure To develop an optimal tower design many detailed assessments were made Similar to choosing the main project concepts the customer needs and engineering specs were considered in choosing each component of the detailed design The main considerations when selecting the material to construct the tower out of were strength and cost The button material needed to be conductive and the rest of the structure had to be non conductive so each button could be activated independently To simulate one nearly continuous button the front of the tower would be comprised of large aluminum buttons with plastic windows between to indicate targets The other three sides are constructed out of PVC which was the
15. http resourcesonbalance com neurocom prod ucts SMARTBalanceMaster aspx gt 2 Nintendo 2009 Wii Fit Plus lt http wiifit com gt 3 Gordon Becker S Lee J Liu Y Wickens C 2003 Introduction to Human Factors Engineering Publisher Prentice Hall 4 US Marine Corps USMC 1996 ANSUR database 5 J Dignan B Pang A Theiss and P Xiong Capacitive Touch Sensor Project A Handbook for Teachers Ohio State University lt http www ece osu edu anderson Touch_Sen sor_Project pdf gt 6 SparkFun Electronics 2009 SparkFun Electronics lt https www sparkfun com commerce product _info php products_id 462 gt ACKNOWLEDGMENTS The Material is based upon work supported by the National Science Foundation under Award No BES 0527358 Any opinions findings and conclusions or recommendations expressed in this material are those of the author and not necessarily reflect the view of the National Science Foundation This project would not have been possible without the support from many faculty members at RIT as well as those at the clinic From conceptualizing the project in Deign Project Management to final testing support was given from the following people Faculty Guide Dr Elizabeth DeBartolo RIT Mechanical Engineering Customers and End Users Dr J J Mowder Tinney Nazareth s PT Clinic Terra Wright Graduate Student at Nazareth David Sprout Electrical Engineer Concept and Design Input Dr
16. ign the MSP430 F16 11 was chosen due to the extremely low power design and the large number of digital inputs and outputs and 50kB flash memory This board also offers ZigBee wireless connectivity for future implementation of communication between multiple towers Furthermore the ability to program in C as well as the numerous online examples significantly shortened the learning curve The MSP430 was mounted on an easily accessible and tiltable wooden platform in the middle of the tower It was placed in the middle of the tower to minimize the amount of wire required to connect it to all seven capacitance buttons and all 8 LED sets The maximum length of wire required for any connection is now half the height of the tower Software Software development was a very important aspect of the project Programming was initially composed in C and transferred to the flash of the MSP430 board via serial JTAG during testing Utilizing ISR techniques to queue button inputs and target statuses the board supports an impossibly small time delay when sending and receiving signals from the tower The program development process was broken down into four phases Phase I included developing a skeleton class design port identification address detection and Input Output testing Utilizing various portions of code during debugging development and testing suggested a strong push towards multiple classes Because of the freedom within th
17. lowest cost non conductive option The deflection calculations were done for the PVC walls to ensure the tower would not deflect under a 501b load which exceeds the amount of force that any patient would be putting on the device The deflection was found to be 00625 for the entire three walled structure and 0697 for a stand alone wall These calculations showed that the deflection of the tower would be negligible To ensure the tower would not easily tip under the force of clients pushing the buttons force calculations were done assuming force is applied at the top of the tower middle and bottom The free body diagram in Figure 5 shows the variables calculated in Table 3 Proceedings of the Multi Disciplinary Senior Design Conference Page 4 While it was proven that the tower could be ergonomically lifted without handles for ease of use for the PT handles were still designed into the device The tower designed to be lifted from the cart to the floor with handles on each side of the device This would reduce the amount of force put on a single wall if it was only lifted using one handle The position of the handle was calculated for a 5 percentile female using the Link Length Proportion Mannequin to hold the device between hip and elbow which is the ergonomically correct position 4 The link length tool states that Hip height 0 530H and Elbow height 0 630H where H is 62 05 for a 5 percentile female The sa
18. mer needs were first assessed It was determined that the clinic needed a device that met the following requirements e Rehabilitative e Safe e Adjustable e Easy to use for Patient and Physical Therapists e Easily Stored and Portable In order to meet the customer s primary needs a list of measurable engineering design specifications were created as well as marginal and ideal values for each These are noted in Table 2 Table 2 Engineering Specifications Engineering Metrics Importance Game response time to from device Distance from patient to target Ideal Value Marginal Value 3500ms 60sec 10cycles 20deg la Se SS ee IAIN O InfToyo TnyJs Me Tn cs st sf eg oO O F oO 5 n Dn N ATO J3 ejs 5 Max tilt angle before fall Time to understand program S S 5deg Time to disassemble 3 3 v v Go ft2 2ft2 101lbs 30lumens 35lumens 60dB 16251bs 100 15mins Showing accuracy of patient location Concept Selection mins 3 D WIN E ia Jklle S12 Io Z 25 Brainstorming sessions were held to generate concepts that could meet the customer s needs and the set specifications The first design was a tri fold design target that would give the patient a grid of lights to reach to The design involved a game that would illuminate buttons on the tri fold and track the patient s ability to hit the targets Figure 2 shows the prototype of this
19. o be added to the side of the device to allow the physical therapist to measure the distance from the patient to the device and record it on the patient report sheet provided for tracking the patient s progress Power Design For easy maintenance for the clinic the device was designed to run on a pack of four interchangeable lithium batteries to operate the device By utilizing a battery powered solution rather than AC wall power we maximize the portability of the device Four AA batteries were used to provide a 6V rail which is then stepped down to 3 3V using a voltage regulator The 3 3V powers the LED s Capacitance Buttons and the Microcontroller Display An LED display screen was placed in the main tower to display current status control actions setup communication and game choices Additionally it displays relevant information following the exercise for the PT to record on a standard worksheet The chosen screen was a Serial Enabled 20x4 LCD with Black on Green display It was chosen based on the low SV power supply it requires and the fact that it could be coded in C The screen also includes firmware that allows adjustment of the backlight brightness The brightness of the screen was designed based on minimal battery consumption and the lighting in the clinic 6 Proceedings of the Multi Disciplinary Senior Design Conference Page 6 Figure 10 Screen on back of tower Board Selection For the needs of the des
20. optimal button solution based primarily on the fact that they do not require the user to actually push a button with a significant amount of force and instead are activated by proximity This way the exercise can focus directly on balance and range of motion rather than ability to generate enough force to activate a button Project P10005 The buttons were created by using a B6OTS O4LT a 16 bit micro controller designed to detect patient touch by detecting the change in capacitance Touching one of the output channels changes the capacitance between the output and ground with the body s capacitance The touch sensor detects the change and the output of that channel and changes voltages which is detected by the microcontroller Figure 8 shows the PCB design that contains one of the Capacitance Touch Sensor Development Tools Sensing IC s which controls four aluminum buttons on the tower Because of the wiring involved between the LED s aluminum buttons and the PCB s thorough testing was of extreme importance A previous project was conducted at The Ohio State University which used the same chips with the functionality that is desired 5 Figure 8 Solderable Bread Board Design Target Illumination RGB LEDs were used as both target and status state indicators A series of RGB LEDs surrounding the target on two sides denotes the current target a successful touch of the target or an incorrect target touch RGB
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