Make a Medical Alert Fall Detector

Abstract

Have you ever wondered what someone would do if they fell, got hurt, and could not get up on their own? What if they were home alone and could not reach a phone to call for help? Or, what if they lost consciousness - is there any way to automatically detect that they fell and needed help? In this project, you will program your own fall detector, a device that can automatically detect when someone has fallen over, then sound an alarm or even send a message to someone else. Devices like these are used by many people with a variety of medical conditions - in this project, you will get to make your own and learn about how they work!

Summary

Areas of Science

Computer Science
Human Biology & Health

Difficulty

Method

Engineering Design Process

Time Required

Short (2-5 days)

Prerequisites

None

Material Availability

This project requires a micro:bit and a computer with an internet connection and a USB port. See materials list for details.

Cost

Low ($20 - $50)

Safety

No issues

Credits

Ben Finio, PhD, Science Buddies

Science Buddies is committed to creating content authored by scientists and educators. Learn more about our process and how we use AI.

https://www.youtube.com/watch?v=MIS-r5K_9WE

Objective

Program a medical alert fall detector device to automatically detect a fall and sound an alarm to alert others.

Introduction

Have you ever wondered how motion controls in video game controllers work? Or how a phone knows to automatically rotate the screen if you turn it sideways? These devices use an electronic sensor called an accelerometer. There are many different types of sensors that can measure all sorts of things, like sound, temperature, and light. Accelerometers measure acceleration, which is a change in speed. That is how a video game controller can detect when you shake it. Accelerometers can also detect which direction gravity is pointing, which helps devices tell which way is up and which way is down. That is how your phone knows to rotate the screen if you turn it sideways!

Accelerometers have other uses too. Think again about the question in the abstract. How could you automatically detect if someone has fallen over? By using an accelerometer! Accelerometers can detect both sudden changes in motion (like the impact of hitting the floor) and orientation (the difference between standing up and lying down). Devices that can automatically detect when someone falls are called fall detectors or fall monitors. More generally, a medical alert device or medical alarm can monitor other things, like whether a person's heart rate or breathing rate has dropped too low, if they have not moved for a certain period of time, or their location (using GPS). Many devices also have a button the person can push to summon help (for example, by calling a family member or 911) and voice communication abilities. These wearable devices can take different forms, like necklaces or bracelets (Figure 1).

Image Credit: Image 1: Medical Guardian, Image 2: Connected Caregiver

Figure 1. Left: a medical alert necklace. Right: a medical alert bracelet.

In this project, you will use a pocket-sized programmable computer called a micro:bit to make a medical alert fall detector (note that technically it is "micro:bit" with a colon in the middle, not "microbit"). The micro:bit has many built-in sensors, including an accelerometer. It uses the accelerometer to measure pitch and roll angles (Figure 2). This lets you write code that does something when the micro:bit tips past a certain angle. 

• When the micro:bit is lying flat with the edge connector pins facing you, both angles are zero. 
• If you tip the micro:bit to the right, the roll angle increases (it will be a positive number).
• If you tip the micro:bit to the left, the roll angle decreases (it will be a negative number).
• If you tip the micro:bit toward yourself, the pitch angle increases (it will be a positive number).
• If you tip the micro:bit away from yourself, the pitch angle decreases (it will be a negative number).

Image Credit: Ben Finio / Science Buddies

Figure 2. Definitions of micro:bit pitch and roll angles.

The micro:bit has other features like buttons, a grid of LEDs (tiny lights), a speaker, and it can even send messages to another micro:bit. The project's procedure will show you how to build a very basic fall detector that detects when the micro:bit tips over, but you can decide what other features you want to use!

Terms and Concepts

• Sensor
• Accelerometer
• Acceleration
• Gravity
• Fall detector
• Fall monitor
• Medical alert device
• Medical alarm
• micro:bit
• Pitch
• Roll
• LED

Questions

• What sensors are built in to the micro:bit?
• What are some features of fall detectors/medical alert devices that you can buy online? 
• What features do you want to program into your micro:bit fall detector?

Materials and Equipment

• micro:bit Go Bundle. This kit contains everything you will need to get started working with micro:bit:
  • micro:bit board
  • micro-USB cable
  • 2xAAA battery holder
  • AAA batteries (2)
• Computer with internet access and USB port

This project follows the Engineering Design Process. Confirm with your teacher if this is acceptable for your project, and review the steps before you begin.

1. If this is your first time using a micro:bit, follow the Getting Started instructions on the micro:bit website to learn how to use your micro:bit and connect it to your computer. 
2. Decide what programming language you will use for your micro:bit:
   1. If you are new to coding, we recommend using Microsoft MakeCode to program your micro:bit. MakeCode is a graphical programming language where you make computer programs using colored blocks of code instead of a text editor. The example code in this procedure uses MakeCode. We recommend following a few of the MakeCode tutorials before you proceed.
   2. You can also program your micro:bit in Python, JavaScript, and Scratch. You may prefer this approach if you already have programming experience in one of these languages. See the Let's Code page for more details.
3. Start a new MakeCode program and make the code shown in Figure 3. You can also access the program on the MakeCode website here. This program will make the micro:bit display a smiley face when it is standing upright and a frowning face when lying flat (Figure 4).
4. Download the program to your micro:bit and test it yourself:
   1. Stand the micro:bit upright on its front edge as shown in the left side of Figure 4. In this position, the pitch angle is 90 degrees. What does the micro:bit display?
   2. Lay the micro:bit flat with the LEDs facing up. In this position, the pitch angle is zero degrees. What does the micro:bit display?
   3. Tilt the micro:bit forward so the LEDs are facing down (hold it up in the air so you can see the LEDs). In this position, the pitch angle is 180 degrees. What does the micro:bit display?

Image Credit: Ben Finio / Science Buddies

Figure 3. Example program.

Image Credit: Ben Finio / Science Buddies

Figure 4. Example code running on the micro:bit.

5. Look at the code so you can understand how it works. The key to this program is an if/else statement. The code tells the micro:bit "IF the pitch angle is outside of a certain range, show a frowny face. ELSE, show a happy face." The condition for the if statement will be true if the pitch variable is less than the angle1 variable OR if the pitch variable is greater than the angle2 variable. That way, when the micro:bit is "vertical," it will show a smiley face. When it "falls over" (either forward or backward), it will show a frowny face. 
6. Try changing the angle1 and angle2 variables and re-downloading the code. What happens if you make the angles bigger? Smaller? What values do you think will work the best for a fall detector if a person is wearing the micro:bit, for example, in their pocket or clipped to a belt?
7. Now it is time to use the engineering design process to design your own fall detector. There is no "right" or "wrong" way to do this, but here are some suggestions for features you could add:
   1. Program a "help" button using the on button A pressed block under Input in the MakeCode menu.
   2. Make the micro:bit play a sound in addition to displaying something with the LEDs.
   3. Experiment with the on shake block under Input. This block lets you detect a variety of motions using the accelerometer (you can change them using the drop-down menu). Do any of these make sense to use as part of a fall detector?
   4. Try using the on loud sound block. Does this block work to detect loud sounds like a person falling or yelling for help?
   5. See the Variations section for some more advanced suggestions.
8. Try some real-world testing of your fall detector.
   1. Use the battery pack that came with your micro:bit so it does not need to be plugged into a USB cable.
   2. Try wearing your micro:bit yourself or asking a volunteer. You will need to figure out how to attach it to a person's clothing or have them put it in a pocket. 
   3. Try some (gentle!) practice falls onto something soft like a couch or pile of pillows. Does your fall detector detect the falls? If not, are there things you can change in your code, like the values of the angle1 and angle2 variables, or other conditions you have set?
9. Try iteratively testing and improving your fall detector based on the results of your tests. 

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Global Goals

The United Nations Sustainable Development Goals (UNSDGs) are a blueprint to achieve a better and more sustainable future for all.

This project explores topics key to Good Health and Well-Being: Ensure healthy lives and promote well-being for all at all ages.

Variations

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