S15: Patient Buddy System (PBS)

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Patient Buddy System

Abstract

A system to enable the doctor or caregivers to remotely detect the physiologic measurements of multiple patients and receive alerts if patients’ conditions get critical or if the patient seeks emergency help. The system measures heartbeat, body temperature, position (sleeping or standing) and activity of the day (step count) continuously. The doctor or caregiver can monitor these measurements and receive alerts in their mobile app.

Objectives & Introduction

Monitor physiologic measurements of the patients: heartbeat, temperature, patient position: sleeping or standing, patient activity: step count
Allows the doctor/caregiver to monitor physiologic data for multiple patients.
Determine if the patient’s physiological conditions are critical.
Automatically alert the doctor/caregiver of the patient’s conditions if critical conditions are reached.
Allow the patient to request for emergency help.

Team Members & Responsibilities

Avinash Closepet Suresh
- Orientation algorithm development and implementation
Girish Bangalore Ramesh
- Board to server communication implementation
Thiruparan Balachandran
- Step count algorithm development, implementation and system integration
Nimmi Bhatt
- Heart rate algorithm and implementation
All of us:
- Collectively worked on end to end system testing and integrating data into an android app

Schedule

Week#	Date	Task	Actual
1	4/14/2015	Order materials, ElectricImp exploration, Patient Position	Completed ordering materials
2	4/21/2015	Develop position details about the subject's orientation via the accelerometer, test different algorithm methods and store the data in Flash.	Completed getting the position details and developing a basic algorithm; Attempts to modify the algorithm are in progress.
3	4/28/2015	End to End Communication: Getting the data from the sensor and displaying it on the app's page.	Completed sending data via electric imp and reading it on the server on other side.
4	5/05/2015	Add other sensors to the system (temperature and heart rate) and work on doctor to patient communication and implement some emergency feature.	Completed integrating the heart rate sensor. The ADC collects the raw heart rate and runs the data through a heart rate algorithm. The algorithm will measure critical levels.
5	5/12/2015	Improve app and work on data analysis on the app's side to make the data look meaningful and interesting.	Completed heart rate algorithm and implemented DSP to get a cleaner heart rate. Completed processing accelerometer data to determine the footsteps and orientation.
6	5/19/2015	Improve and implement the android app and test the entire system from end to end.	Planned
7	5/22/2015	Demo!	Planned

Parts List & Cost

Item#	Part	Vendor	Vendor P/N	Cost	Link
1	SJ One Board	Preet	n/a	79.99$	http://www.socialledge.com/sjsu/index.php?title=SJ_One_Board
2	Pulse Sensor	Sparkfun	SEN-11574	24.95$	https://www.sparkfun.com/products/11574
3	Electric Imp	Sparkfun	WRL-11395	29.95$	https://www.sparkfun.com/products/11395
4	Electric Imp Breakout Board	Sparkfun	BoB-12886	12.95$	https://www.sparkfun.com/products/12886
5	Temperature Sensor-TMP102	Sparkfun	SEN-11931	05.95$	https://www.sparkfun.com/products/11931

Total Cost: 153.79$

Design & Implementation

Hardware Design

Discuss your hardware design here. Show detailed schematics, and the interface here.

Hardware Interface

In this section, you can describe how your hardware communicates, such as which BUSes used. You can discuss your driver implementation here, such that the Software Design section is isolated to talk about high level workings rather than inner working of your project.

Pulse sensor:
- Sends the raw photoplethysmograph signal to the on-board ADC and the signal is sampled every 2ms.
Accelerometer sensor:
- On-board accelerometer sensor is interfaced via the I2C bus to get the 3-Axes acceleration.
Temperature sensor:
- External temperature sensor, TMP102, is interfaced via the I2C bus to get on-body temperature readings.
Electric Imp:
- Collected data is sent to the server via Electric Imp. UART bus is used for communication between the board and Electric Imp.

Software Design

Show your software design. For example, if you are designing an MP3 Player, show the tasks that you are using, and what they are doing at a high level. Do not show the details of the code. For example, do not show exact code, but you may show psuedocode and fragments of code. Keep in mind that you are showing DESIGN of your software, not the inner workings of it.

Firmware of the SJ One Board is designed using FreeRTOS. C++ language is used to write the firmware. The drivers provided by the SJ One Board manufacturer are used for low level application. Each task is assigned to collect a measurement, process an algorithm on it and compute the result. To maintain the high accuracy sampling frequency of the pulse sensor, the RIT- repetitive timers, interrupt service routine and binary semaphore are used. To maintain the sampling frequency of the accelerometer and the temperature sensor vTaskDelay is used. Since the clock cycles spent on the tasks are low, using the vTaskDelay was accurate enough to get a reasonably constant sampling frequency of the accelerometer and the temperature sensors.

ALGORITHMS:

1. Heart Rate calculation:

The heart rate (bpm) is calculated by sensing the photoplethysmograph signal from the Pulse Sensor. By using the adc0_get_reading() function, we are able to read the analog signal from the sensor. Since the analog signal we were getting was noisy, we used a standard median filter with window size of 3 to eliminate the noise. By comparing the current data with that of the past data and the future data, we are able to find the peak and trough of the signal. By calculating the average time between the 10 consecutive peaks, the inter-beat interval (IBI) is calculated, from which the heart rate is determined.

Dichrotic notch

Algorithm Pseudocode:
- Find the first peak of the signal, last peak time = current time.
- Find the second peak, current peak time = current time
- Interval = last peak time - current peak time.
- If interval is < (Interbeat Interval *(3/5) ). Ignore it- this helps to eliminate the dicrotic notch.
- Calculate the average of ten intervals
- Heart rate = 1min/ interval and loop back to the find first peak..

2. Step Count Algorithm:

The step count is calculated using the on-board accelerometer. Initial threshold for the step count is calculated based on the R&D, as mentioned in the implementation part.
Pseudocode:
- Initialize the dynamic Threshold based on research value
- energy = sqrt(x*x + y*y + z*z) //Calculate the energy
- Find the peak and the trough, amp = peak - trough
- if((amp > dynamic threshold*0.5)&&(current_time-last_step_time > 0.4s)) {step_count++} //Calculate the amplitude
- NOTE: 0.4 sec was calculated based on the following research paper, which states that on average a human being can walk up to 150 steps per min. Source: http://www.computer.org/csdl/proceedings/icisa/2013/0602/00/06579332.pdf
- Calculate the harmonic average of the past 5 amplitudes
- Update the dynamic threshold = harmonic average and then loop back to energy calculation.

3. Patient Orientation:

Pseudocode:
- Read the z acceleration
- If z>700 for 10sec, then patient position = lying down
- If z<700 for 10sec, then patient position = standing.

4. Critical Conditions:

Determine if the heart rate is critical
Determine if temperature is normal range
Determine if emergency is requested by the patient

CLOUD AND THE APP COMMUNICATION

The cloud provided by the Electric Imp is used to pass the data to the mobile app. The Electric Imp consists of two components: 1) The device and 2) The agent-the electric imp cloud server. The device is the actual hardware which sends the data to the agent and the mobile app will pull the data from the agent (server). Squirrel language is used to write the software for the agent and the device. The android mobile app is created in Java.

Logic:
- 1). Device:
  - Receive data from the SJ ONE Board through UART.
  - Send the data to the agent- Example code: agent.send("HR", HR);
- 2). Agent:
  - Receive the data from the device
  - Store them in the server.
  - On http request data is sent back using the following code:response.send(200,format("heart=%d,temprature=%d,poistion=%d,step=%d,emergency=%d",HRval,tempval,poval,stepval,eoval));

Implementation

This section includes implementation, but again, not the details, just the high level. For example, you can list the steps it takes to communicate over a sensor, or the steps needed to write a page of memory onto SPI Flash. You can include sub-sections for each of your component implementation.

Research and Development : 1). Heart Rate: • photoplethysmo signal of the pulse sensor is studied by reading the analog signal of the pluse senser. This analog signal is read every 2mili sec and transferred to the computer through the UART and this analog data is logged on the computer for ten minutes using the Terminal v1.9b software ( https://goo.gl/yJZCC ). • This data is imported to the Matlab, and the data is plotted as shown in the figure below ((((())))). • According to the figure the data obtained contained some noise, different filters were tried and tested to eliminate the noise. Finally Standard median filter with the window size 3 was found as the optimum filter with low clock cycles. • This figure showa the filtered signal.((((()))))). • This filter is implemented on the target board SJ-ONE board and the filtered signal is fed to the heart rate algorithm. 2).Step Count: • Read the X,Y, Z acceleration of the on board sensor and saved the data on the SD card using Storage::append("1:myfile.txt",data,28,0);. • By using the setup as shown in the picture, acceleration of x,y,z for 50 steps were collected on the SD card. • Read the data from the SD card and transfer the data through the UART to the computer • Data is loaded on to the MatLab and step count algorithm was implemented in matlab first and this algorithm was verified using this data.((((()))))). • Figure is energy vs time plot while walking . energy = (x*x +y*y +z*z) • This matlab code was ported to the sjsu board.

Testing & Technical Challenges

Describe the challenges of your project. What advise would you give yourself or someone else if your project can be started from scratch again? Make a smooth transition to testing section and described what it took to test your project.

Include sub-sections that list out a problem and solution, such as:

My Issue #1

Discuss the issue and resolution.

Analyzing sensor data:
- Issue 1: We had difficulty interpreting data. When we first collected data, we noticed some numbers change, but we didn't know how to make sense of the data. To fix this issue, we plotted the data in Matlab and ran it through some filters (such as LPF to remove noise from motion artifact) and then extracted the values from the processed data to see if they gave meaningful results. Once the data looked meaningful, we implemented those algorithms in C.
- Issue 2: IoT Device: We faced connectivity issues with using Electric Imp. The electric imp would not always work reliable on different Wifi locations.

Conclusion

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Project Video

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Project Source Code

Sourceforge Source Code Link

References

Acknowledgement

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References Used

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Appendix

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