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About the Moving Average
About the Moving Average
In our new program, it used the moving average theory to calculate the heart rate. So, I will introduce what is moving average theory and how it use in the program.
The moving average theory is a calculation to analyze, count data by creating a series of averages value of different subsets form the whole data.
At first, people would set a number of subsets, this number is always same.Use this group of subsets.to calculate the first element of the moving average. Then, the subset would shifting forward but the number of group of the subsets do not change. Use the new group of subsets to get the second element of the moving average. This process is repeated over the entire data series.
In the program, we use the moving average to calculate the heart rate. We only have three subsets and every time we only gay two peaks and use this two peas to get the heart rate. However, we get the subsets every frequently, it can ensure the accuracy of the heart rate.
Tag :
Background,
Week 8,
How does pulse sensor works ??
How does the IR pulse sensor works ??
Principle of photoplethysmogram (PPG) Measurement !!
The pulse sensor is made using an infra-red emitter and detector. Light emitted by an infra-red emitter enters the skin and is diffusely scattered. The peak wavelength emitted by the emitter is typically in the range on 900nm < λ < 960nm. The detector placed on the other end captures a part of this diffused light. As light propagates through the tissues, a fraction of its intensity is absorbed by pulsating blood. Hence, when blood volume increases during the cardiac systole the captured intensity decreases creating a pulse-like photoplethysmogram (PPG) signal which reflects the blood volume changes in the arterioles. Furthermore, light absorptivity of haemoglobin (Hb) is significantly greater than that of oxyhemoglobin (HbO2) at 660nm. As arterial blood have high concentration of HbO2 and contrastingly, venous blood have high concentration of Hb, the sensor is able to detect the variation in both the systole and diastole stages.
Principle of photoplethysmogram (PPG) Measurement !!
The pulse sensor is made using an infra-red emitter and detector. Light emitted by an infra-red emitter enters the skin and is diffusely scattered. The peak wavelength emitted by the emitter is typically in the range on 900nm < λ < 960nm. The detector placed on the other end captures a part of this diffused light. As light propagates through the tissues, a fraction of its intensity is absorbed by pulsating blood. Hence, when blood volume increases during the cardiac systole the captured intensity decreases creating a pulse-like photoplethysmogram (PPG) signal which reflects the blood volume changes in the arterioles. Furthermore, light absorptivity of haemoglobin (Hb) is significantly greater than that of oxyhemoglobin (HbO2) at 660nm. As arterial blood have high concentration of HbO2 and contrastingly, venous blood have high concentration of Hb, the sensor is able to detect the variation in both the systole and diastole stages.
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Inventory:
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Siliconix / Vishay TCRT1000 PHOTOINTERRUPTER REFLECTIVE PHOTOTRANSISTOR 4-PIN BULK
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20 pcs Photo Light Sensitive Resistor Photoresistor Optoresistor 5mm GL5516 5516
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pulsesensor Arduino Pulse Heart Rate Sensor - Black + White
Price: $35.24+$10 Shiping
Arduino Wireless Bluetooth Transceiver Module Slave 4Pin Serial + DuPont Cable
Price: $10.98
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Operational Amplifier
Operational Amplifier
What is operational amplifier ?
An operational amplifier (or an op-amp) is an integrated circuit (IC) that operates as a voltage amplifier. An op-amp has a differential input. That is, it has two inputs of opposite polarity. An op-amp has a single output and a very high gain, which means that the output signal is much higher than input signal. An op-amp is often represented in a circuit diagram with the following symbol:
These amplifiers are called "operation" amplifiers because they were initially designed as an effective device for performing arithmetic operations in an analog circuit. The op-amp has many other applications in signal processing, measurement, and instrumentation.
Feed back
An ideal opamp has infinite gain. It amplifies the difference in voltage between the + and - pins. Of course in reality this gain is not infinite, but still quite large.
Why feed back is needed ?
The output of the opamp (at to some extents the input also) is constrained by the power supply, we can't get out more than the supply puts in.If we simply put signals into the opamp without feedback it would multiply them by infinity and get a binary output (it would saturate at the supply rails)So, we need some way of controlling the gain. That is what the feedback does.
Pros:
- Can increase or decrease input impedance (depending on type of feedback)
- Can increase or decrease output impedance (depending on type of feedback)
- Reduces distortion (increases linearity)
- Increases the bandwidth
- Desensitizes gain to component variations
- Can control step response of amplifier
Cons:
- May lead to instability if not designed carefully
- Amplifier gain decreases
 |
| LM741 The opamp that the group is using |
Tag :
Background,
Week 4,
Arduino !!
Arduino official website:
“ARDUINO IS AN OPEN-SOURCE ELECTRONICS PROTOTYPING PLATFORM
BASED ON FLEXIBLE, EASY-TO-USE HARDWARE AND SOFTWARE. IT'S INTENDED FOR
ARTISTS, DESIGNERS, HOBBYISTS AND ANYONE INTERESTED IN CREATING INTERACTIVE
OBJECTS OR ENVIRONMENTS.“
Feature:
1 It is a circuit design platform base on CC open source
2 The software is free to download, and open to everyone
3 Arduino allow to use ICSP to load bootloader on the IC
chip
4 Provide USB hub and DC 5V
5 Support a lot of program such as: Adobe Flash, Max/MSP,
VVVV, Pure Data, C, ect….
Why Arduino?
Arduino simplify a lot of process of working with microcontroller,
the advantage of it are:
1.
Inexpensive – Arduino is relatively inexpensive
compared to other circuit. The cost can be lower than 50$
2.
Cross platform – Arduino support Window, Mac OSX
and Linux
3.
Extensible software
Extensible hardware-Arduino is based on Amel’s ATMEGA8 and ATMEGA168 microcontrollers.
Project Overview
The Problem:
Heart health problem has been a big issues for many years. There are lot of heart health monitor product in the market to help them keep track their health. However there are patient, who can not take care themselves even when they know the heart problem is coming. If the patient is alone, and he does not has the ability to ask for any assistance. The heart problem can be fatal to the patient.
The Design Objective: 1.Design a sensor that can sense heart beat
2. Design algorithm to accurately calculate heart beat
3. Design a mobile application that connects to the sensor
4. Make the design minimal and aesthetically pleasing
The workflow of heart rate monitor
Heart health problem has been a big issues for many years. There are lot of heart health monitor product in the market to help them keep track their health. However there are patient, who can not take care themselves even when they know the heart problem is coming. If the patient is alone, and he does not has the ability to ask for any assistance. The heart problem can be fatal to the patient.
The Design Objective: 1.Design a sensor that can sense heart beat
2. Design algorithm to accurately calculate heart beat
3. Design a mobile application that connects to the sensor
4. Make the design minimal and aesthetically pleasing
The workflow of heart rate monitor
The monitor will check the heart rate of users. after record a number of times, it will send those record to the phone by using Bluetooth or WiFi.
After the phone get the records, it will arrange the records and compare with the older records and try to find out weather user get ill.
The application will help doctors and hospitals track one or more patients at the same time. The application also can notice not only the hospitals and doctors, but also the people who setting in the application if the patients' heart rate becomes abnormal. It can help patients get treatment more quickly.
Tag :
Background,
Week 1,
