Respiratory training is a critical component of many rehabilitation plans, including those of stroke patients. Many current respiratory training techniques lack efficient methods for quantifying progress and updating testing parameters. A previously-developed microcontroller-based device, designed in conjunction with clinicians at the Institute for Rehabilitation Science and Engineering at Madonna Rehabilitation Hospital, has demonstrated promising results. Here, a prototype of a revised device that is network connected and remoatly sends trial information is presented.\ The proposed device demonstrates enhanced functionality, while being smaller and using less power than the original prototype

Carlson, Jay D.

Parkison, Steven A.

Pérez, Lance C.

English

DigitalCommons@University of Nebraska

University of Nebraska - LincolnDigitalCommons@University of Nebraska - LincolnFaculty Publications from the Department ofElectrical and Computer Engineering Electrical & Computer Engineering, Department of2013Improved Microcontroller-Based ElectronicRespiratory TrainingSteven A. ParkisonUniversity of Nebraska-Lincoln, sparkison@huskers.unl.eduJay D. CarlsonUniversity of Nebraska-LincolnLance C. PérezUniversity of Nebraska-Lincoln, lperez@unl.eduFollow this and additional works at: http://digitalcommons.unl.edu/electricalengineeringfacpubPart of the Computer Engineering Commons, and the Electrical and Computer EngineeringCommonsThis Article is brought to you for free and open access by the Electrical & Computer Engineering, Department of at DigitalCommons@University ofNebraska - Lincoln. It has been accepted for inclusion in Faculty Publications from the Department of Electrical and Computer Engineering by anauthorized administrator of DigitalCommons@University of Nebraska - Lincoln.Parkison, Steven A.; Carlson, Jay D.; and Pérez, Lance C., "Improved Microcontroller-Based Electronic Respiratory Training" (2013).Faculty Publications from the Department of Electrical and Computer Engineering. 299.http://digitalcommons.unl.edu/electricalengineeringfacpub/2991Improved Microcontroller-Based ElectronicRespiratory TrainingSteven A. Parkison, Jay D. Carlson, and Lance C. PérezUniversity of Nebraska-Lincoln, Department of Electrical EngineeringLincoln, NE 68588-0511Email: sparkison@huskers.unl.edu, jcarlson@unl.edu, lperez@unl.eduAbstract—Respiratory training is a critical component of manyrehabilitation plans, including those of stroke patients. Manycurrent respiratory training techniques lack efficient methodsfor quantifying progress and updating testing parameters. Apreviously-developed microcontroller-based device, designed inconjunction with clinicians at the Institute for RehabilitationScience and Engineering at Madonna Rehabilitation Hospital,has demonstrated promising results. Here, a prototype of arevised device that is network connected and remoatly sendstrial information is presented.\ The proposed device demonstratesenhanced functionality, while being smaller and using less powerthan the original prototype.I. INTRODUCTIONSOME neurological conditions can affect respiratorydrive and therefore cause speech impairment. Alveolarair pressure varies during speech – increasing sharply at thestart of an utterance and then staying constant for the durationof that utterance – and can be used as an indicator of respi-ratory drive [1]. Intraoral air pressure during the productionof voiceless plosives can in turn be used to assess respiratorysupport for speech.There have been several attempts to use Intraoral air pres-sure to improve respiratory therapy, including biofeedback“blow-bottle” approaches [2], [3]. While these approaches areeffective, they lack the ability to collect performance data orindividualize the trial specifications including trial durationand upper/lower pressure thresholds. And while there aresystems that do not have those downsides[4], they usuallyare not portable, and thus patients cannot practice at home.With the proliferation of network attached devices, includingremote data logging functionality to such a system so that itcan remotely upload trial results to a central server is bothdesired and necessary.Here, a portable network connected respiratory trainingdevice is presented that is easy for patients to use at homebut has the ability to collect trial data and set trial specifica-tions remotely. In this paper we will present our prototype,developed on a 32-bit microcontroller with a graphical liquidcrystal display used for feedback.A. Previous WorkThe Aerowin RT [4] is a full featured aerodynamic testsuite. Using a National Instruments 16-bit I/O card hookedup to a desktop computer’s PCI slot, it collects data onair pressures, flow, airway resistance (including nasal cavity,velopharyngeal, and laryngeal airway resistance), and audiolevels. It collects these measurements as the user is speakingover a several minute session. The system is designed to beused in a laboratory setting to diagnose speech disorders andallows the clinician to design test protocols.A portable device called the Madonna Expiratory Respira-tory Trainer (MERT) has been presented before [5]. MERTwas designed to be a take-home system that users couldoperate with out the supervision of a clinician, but that stillrecorder trial data for later analysis. That system is housedin a 20 × 15 × 7.6 cm box that is powered by two AAAbatteries. The system uses a PIC18F 8-bit microcontroller thatoperated at 20MHz and has 32KB of on-board flash memory.This portable system can hold up to 40 trials before needingto upload the trial data to a computer via a serial port. Thetrial data can be opened in a LabVIEW program that providesa graphical view of the data for each trial. The softwarealso allows the device to be programmed with individualizedtherapeutic regimens, including pressure thresholds and trialdurations. While this system was an improvement over otherattempts it had some core problems. It was not wirelesslynetwork connected and instead needs to connect to a computerover RS-232. And while it is more portable then the AerowinRT, it is still has a large form factor and is power inefficient.The device has a pressure sensor, a power switch, twopush buttons, a monochromatic, character based, liquid crystaldisplay, and 12 LEDs. One of the push buttons is used to starta trial. The user breathes into a rubber hose connected to thepressure sensor. The color-coded LEDs provides feedback onhis or her expiratory pressure compared to the target pressure.This system can be seen in Figure 1.B. .NET Micro FrameworkTraditional embedded applications are written in low-levelANSI C. While this can allow for more efficient applications,it has longer development times when compared to higherlevel languages. Microsoft’s open source .NET Micro Frame-work (NETMF) aims to expedite the development process ofembedded platforms by leveraging existing .NET ecosystemtechnologies [6]. It uses a version of Microsoft’s CommonLanguage Runtime (CLR) that only needs 256 KB of flash and64 KB of RAM while still having many of the CLR librariesused in the full version of .NET Framework. It has becomeU.S. Government work not protected by U.S. copyright2Figure 1. Existing MERT device with its monochromatic LCD, two buttoninterface, and large form factor.popular for investigating or developing low-power wirelesssystems [7]. NETMF has also proven useful in developingmobile medical systems for monitoring ECG signals [8], evenunder real-time constraints [9].Another issue with embedded platforms is prototyping hard-ware. While many processors are available on manufacturer-supplied development kits, these kits rarely provide the sortsof hardware peripherals needed to fully implement a prototypeof the embedded system, and instead are designed moresoas a marketing tool to advertise the functionality of thedevice; not to actually provide a useful platform for prototyp-ing.Therefore, much time is spent designing and debuggingthese hardware platforms – platforms that, by and large, aremodular and reuse blocks of functions. .NET Gadgeteer is aninteroperability standard of hardware and software to makeprototyping with NETMF easier [10]. The Gadgeteer standarddefines “sockets” that allow peripherals to interface with thesystem processor on a Gadgeteer main board. Microsoft hasbuilt an add-on for NETMF and Gadgeteer into Visual Studio,which gives the whole ecosystem a familiar and easy-to-useintegrated development environment. Gadgeteer and NETMFcan dramatically speed up development of networked attachedembedded systems, particular for the Internet of Things [11].II. IMPLEMENTATIONFor many of the reasons stated previously, we chose todevelop the system using NETMF on a Gadgeteer board. TheFEZ Hydra from GHI was selected as the mainboard for itsability to support a liquid crystal display. There are currentlyseveral other Gadgeteer mainboards on the market, but theFEZ Hydra was also chosen because it is the fastest andis completely open source. The FEZ Hydra has an ARM9processor running at 208 MHz, with 16 MB SDRAM and4 MB flash memory. The GHI T35 Display Module – afull color, 320x240 pixel, 8.9 cm liquid crystal display– wasused to provide a graphical interface to the user.. The sameHoneywell 164PC01D37 differential pressure sensor used inthe previous MERT device was used for sensing expiratorypressure. The hardware for the prototype can be seen in Figure2. This hardware system cost slightly more than $200.Figure 2. Prototype hardware consisting of (clockwise from top left) USBpower supply, FEZ Hydra main board, T35 LCD, Costume built UI board,and the Honeywell 164PC01D37. The WiFi module is not shown.A. User Interface OverviewThe device behavior and graphical user interface weremodeled after the previous MERT device which was designedwith input from a speech language pathologist and individualswith motor speech disorders [5]. The proposed device isdesigned to be simple to operate: a trial begins with the pushof the start button; a countdown screen appears, preparing theuser for the trial; once the trial begins, two bar graphs appear– one indicating the goal pressure and one indicating currentpressure on the pressure sensor. The user tries to match thetwo bar graphs by blowing into the rubber hose attached tothe pressure sensor. During the trial, another countdown timerinforms the user of how much of the trial is left. Once thetrial ends, the cumulative deviations from the goal is shown.The device is ready to start another trial, initiated again bythe user pressing the button. The bar graph feedback systemis shown in Figure 3.B. Networking and Server InfrastructureWireless connectivity is provided by a GainSpanGS1011MIPS. The GS1011MIPS is a WiFi Module thatsupports data rates up to 11 Mbps and is compliant with802.11 b/g/n wireless networks. The device is designed toremotely upload trial results to a database for analysis.III. METHODSTo test the portability and effectiveness of our new sys-tem, several characteristics were compared, including volume,memory, and power consumption. The volume was computedfrom measurements of the parameter of each device and thepower consumption was measured as a trial was running. Theease of prototyping new features was also compared.3Figure 3. Above: Bar graphs representing goal pressure and current pressuregive the user feedback on trial progress. Below: The user interface of the oldsystem consisting of a series of LED indicating pressure level in relation tothe goal pressure.eIV. RESULTSThe new systems outperforms the previous MERT device inseveral quantifiable ways. The MERT device used nearly threewatts of power and could only store 40 trials at a time. Thenew system uses only 1.25 watts and has 4 MB of FLASHmemory, nearly eight times that of the MERT device. TheMERT device takes up 2280 cubic centimeter, while the newsystem takes up no more then 500 cubic centimeters. The sizecomparison can be seen in Figure 5. The decrease in sizeand power consumption coupled with the increase in memoryover the MERT device make this system considerably moreportable.Qualitatively, the new system outperforms the previousMERT device in that is much easier to add new featuresand its potential for future development. The MERT device,conversely, would be rather difficult to add new functionalityto, since its firmware is written in C and is running on an 8-bitmicro controller. The comparison between the two devices issummarized in Table I.InternetServerProposed deviceWiFi Access PointFigure 4. The proposed device uses WiFi to connect to a central sever totransmit trial information and receive trial parameters.Figure 5. Visual size comparison between MERT device and prototype device.V. CONCLUSIONThese results show that the new system succeeds at be-ing portable and flexible. It compared favorably against theprevious MERT device in both terms of portability and per-formance. While it is not designed to replace a diagnosticdevice such as the Aerowin RT, these results show it hasthe promise of supplementing this those device by enablingAttribute MERT device Our devicePower (W) 2.93 1.25Memory (KB) 256 4096Volume (cubic cm) 2280 418Table IPHYSICAL ATTRIBUTE COMPARISON BETWEEN MERT DEVICE AND OURDEVICE4patients to receive respiratory therapy sessions away from aclinical environment. It also has shown the ability to allowclinicians the ability to individualize care.A. Future WorkFuture work will including adding further wireless func-tionality, such as adding ability to remotely change trialparameters. Work will also include improving the interfacethat clinicians use to aces the database, allowing for variousforms of trial analysis.The current prototype has no enclosure and has rudimentaryinput hardware. Designing hardware for users who potentiallyhave poor motor skills is a difficult challenge that requiresthe consideration of many facets of human factors and er-gonomics. The system presented in this paper was designedto be portable, but to ensure usability the enclosure and userinterface will need to undergo an iterative design process withfeedback from potentially users and caregivers.ACKNOWLEDGMENTThe authors would like to thank the University of Nebraska-Lincoln UCARE Grant Program for supporting this project.REFERENCES[1] H. J. Hixon T, Evaluation and management of speech breathing disor-ders: Principles and methods. Redington Brown, LLC., 2005.[2] W. Hixon T, Hawley J, “An around -the-house device for the clinicaldetermination of respiratory driving pressure,” Journal of Speech andHearing Disorders, vol. 47, pp. 413–415, 1982.[3] S. E. B. K. Yorkston K, Beukelman D, Management of motor speechdisorders in children and adults. ProEd, 1999.[4] B. S, “Aerowin rt, version 1.2,” Neuro Logic Inc, Tech. Rep., 2003.[5] P. L. L. P. K. P. Hakel M, Beukelman D, “Madonna expiratoryrespiratory trainer- a self practice device for improving the controleof alveolar pressure,” Journal of Medical Speech-Language Pathology,vol. 16, 2008.[6] Microsoft. What is the .net microframwork.http://www.netmf.com/what-is-the-net-micro-framework.aspx. Mi-crosoft. [Online]. Available: http://www.netmf.com/what-is-the-net-micro-framework.aspx[7] R. Hilbrich, “An evaluation of the performance of dpws on embeddeddevices in a body area network,” in Advanced Information Networkingand Applications Workshops (WAINA), 2010 IEEE 24th InternationalConference on, april 2010, pp. 520 –525.[8] D. Janckulik, L. Motalova, and O. Krejcar, “Software solutions forimplementation of biotelemetric system,” in Applied Electronics (AE),2010 International Conference on, sept. 2010, pp. 1 –4.[9] O. Krejcar, D. Janckulik, L. Motalova, and K. Musil, “Real timeprocessing of ecg signal on mobile embedded monitoring stations,”in Computer Engineering and Applications (ICCEA), 2010 SecondInternational Conference on, vol. 2, march 2010, pp. 107 –111.[10] Microsoft. What is .net gadgeteer. http://www.netmf.com/gad-geteer/what-is-gadgeteer.aspx. Microsoft. [Online]. Available:http://www.netmf.com/gadgeteer/what-is-gadgeteer.aspx[11] S. Hodges, S. Taylor, N. Villar, J. Scott, D. Bial, and P. T. Fischer,“Prototyping connected devices for the internet of things,” Computer,vol. 46, no. 2, pp. 26 –34, feb. 2013.

Improved Microcontroller-Based Electronic
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Improved Microcontroller-Based Electronic Respiratory Training

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