Build an Obstacle-Detecting Walking Stick for Blind People

Abstract

Many individuals who are blind or visually impaired use canes to navigate their surroundings, using their sense of touch to detect obstacles. What if you could create an electronic cane that emits an audible warning before coming into contact with an object? This project allows you to do just that by incorporating an ultrasonic distance sensor and a buzzer to alert the user of approaching obstacles. You can customize the cane by adding additional features or altering the design, such as using a vibration motor instead of a buzzer. The possibilities for customization are endless!

Summary

Areas of Science

Electricity & Electronics
Human Biology & Health

Difficulty

Method

Engineering Design Process

Time Required

Short (2-5 days)

Prerequisites

Previous experience with Arduino is recommended before you try this project. See our How to Use an Arduino page.

Material Availability

A kit is available from our partner Home Science Tools®. See the Materials section for details.

Cost

Average ($50 - $100)

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=7hmTb7Iqm4s

Objective

Design and build an electronic cane that emits a beeping noise when the user approaches an obstacle.

Introduction

Check out this video from the Broadcom Foundation showing projects by Damini Jordan and Johan Santana from the Renaissance Youth Center in Bronx, New York:

https://www.youtube.com/watch?v=51Hg5HpVZFA

People who are blind or visually impaired can use a variety of assistive technologies to help them navigate the world. For example, they can use braille to read physically printed text, and screen reader software that reads text on a computer screen out loud. Many of them use white canes to detect obstacles when walking, by sweeping the cane back and forth in front of them as they walk (Figure 1). The canes are white to help other people nearby (like pedestrians and drivers) identify that the user is visually impaired and use appropriate caution. The main color of the cane and the significance of any additional colors, like red bands signaling that the user is also hard of hearing, can differ from country to country.

Image Credit: US Government / Public Domain
Figure 1. A woman crossing the street using a white cane.

Some people use smart canes or electronic walking sticks that have additional features. For example, a stick might connect to an app on your phone and have built-in microphones and speakers to work with voice commands. Some sticks contain an ultrasonic distance sensor to detect obstacles. An ultrasonic sensor emits a burst of ultrasonic sound and measures how long it takes the sound wave to reflect back to the sensor - just like a bat uses sonar to echolocate objects. The stick can then provide some sort of feedback to the user - like a beep or vibration - to alert them of the obstacle. Depending on the orientation of the sensor, it can detect different obstacles or scenarios. For example:

• A forward-facing sensor will detect obstacles in front of the user before the stick makes physical contact with them.
• An upward-facing sensor can detect obstacles above ground level (such as a protruding shelf, table, tree branch, etc.) that would not normally be detected by the cane's tip.
• A downward-facing sensor can detect the absence of a nearby surface or a sudden increase in distance - such as a hole in the ground, the top of a flight of stairs, or the edge of a curb when stepping off a sidewalk.

In this project, you will need to decide how many ultrasonic distance sensors to use and what direction(s) they will face. You will also need to decide how to provide feedback to the user - using a buzzer, vibration motor, or something else. The instructions in the procedure will show you how to build a walking stick with a single ultrasonic sensor and a buzzer that beeps faster as an obstacle gets closer, but what you build is up to you. Check out the following video to learn more about ultrasonic distance sensors, and our How to Use an Arduino page for tutorials on other parts like buzzers and motors.

https://www.youtube.com/watch?v=n-gJ00GTsNg

https://www.youtube.com/watch?v=gj-H_agfd6U

Terms and Concepts

• Blind
• Visually impaired
• Assitive technology
• White cane
• Smart cane
• Electronic walking stick
• Ultrasonic distance sensor
• Sonar
• Echolocate

Questions

• What are some ways that blind or visually impaired people can navigate safely when walking around?
• Search online for "smart cane" and "electronic walking stick" etc. What are some features of canes/sticks that you can buy online?
• What features do you want to include in your cane/stick?

Materials and Equipment

Recommended Project Supplies

Get the right supplies — selected and tested to work with this project.

View Kit

This is an engineering design project. The exact materials you will need depend on what you decide to build. The list below is for the circuit shown in the procedure with one ultrasonic sensor and one buzzer. You may wish to add multiple ultrasonic sensors or other outputs like a vibration motor. 

• Electronics Kit for Arduino, available from our partner Home Science Tools®. The kit includes the following parts that you need for this project:
  
  • Arduino-compatible microcontroller board
    • Note: This project will work with the Arduino UNO R3, UNO R4 Minima, UNO R4 WiFi, and compatible third-party boards.
  • USB cable
  • Breadboard
  • Jumper wires
  • 9V battery
  • 9V battery snap connector
  • HC-SR04 ultrasonic distance sensor
• Active buzzer. The example code in this project is for an active buzzer that produces a single tone. If you want to use the Arduino tone() function to produce sounds with different pitches, you can use a passive buzzer instead. See our buzzer tutorial video to learn about the differences between the two types.
• 22 AWG solid-core wire
• Mini breadboard
• 5.5x2.1mm barrel jack connector with switch
• Wooden dowel, walking stick, cane, etc. to modify
• Materials to attach things to your dowel, such as zip ties, electrical tape, double-sided foam tape, duct tape, a hot glue gun, etc.
• Scissors
• Wire strippers

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.

Before you begin: Review How to Use an Arduino Tutorials 1-3.

Design Your Walking Stick

It may be tempting to just jump right in and start building something, but the engineering design process involves some careful planning and research before you build a prototype. See our engineering design process guide for more details, but here is an overview of some things you should consider for this project:

• What problem are you trying to solve? Specifically, as discussed in the introduction, what obstacles are you trying to detect?
• What features are available on existing smart/electronic canes or walking sticks? What type(s) of sensor(s) do they use?
• What features do you want to include in your design?
• Especially if you are using multiple sensors to detect obstacles in different directions, how will you alert the user? For example, could you use different beeping or vibration patterns to indicate obstacles in different locations?

Prototype The Circuit

You should build and test your circuit on a breadboard before you mount everything to a stick. Figures 2 and 3 show one possible breadboard layout and circuit diagram for a circuit with a single ultrasonic sensor and buzzer. You will need to modify the circuit for additional sensors or outputs. You can access a Tinkercad Circuits simulation of the circuit here.

Important: depending on where you bought your breadboard, the left/right orientation of the power (+) and ground (-) buses may be reversed. 

1. Connect the ultrasonic sensor
   1. GND pin to GND
   2. ECHO pin to Arduino pin 7
   3. TRIG pin to Arduino pin 6
   4. VCC pin to 5V
2. Connect the buzzer
   1. Negative (-) pin to GND
   2. Positive (+) pin to Arduino pin 8
3. Connect power and ground (remember that left-right orientation may be switched from what you see in Figure 2)
   1. Arduino 5V pin to power (+) bus 
   2. Arduino GND pin to ground (-) bus

Image Credit: Ben Finio / Science Buddies

Figure 2. Breadboard diagram.

Image Credit: Ben Finio / Science Buddies

Figure 3. Circuit schematic.

Test the Code

If your circuit is identical to Figures 2 and 3, you can download our example code. You will need to modify the code if you add more sensors or outputs.

1. Upload the code to your Arduino.
2. Hold your hand in front of the ultrasonic sensor and slowly move it back and forth. Listen to how the buzzer responds.
3. If the buzzer does not work, double-check that you have all of the connections correct and that no wires are loose. 
4. Experiment with changing the threshold, buzzerDelayMin, and buzzerDelayMax variables in the code. How do they let you change the buzzer's behavior?
5. Once you have the code working the way you want it, you are ready to mount your circuit on the walking stick.

Build the Walking Stick

You can decide how to mount your circuit to your walking stick. How you do this will depend on the materials you have available and the criteria for your project - are you just building a prototype for demonstration at a science fair, or do you want something more durable for long-term use? Figures 4, 5, and 6 show an example, but how you build your stick is up to you.

1. Mount the Arduino and breadboard to the top of the stick (near the "handle") using tape. This keeps the heavier weight closer to the user's hand and easier to manage.
2. Power the Arduino with a 9V battery in line with a barrel jack connector that has a built-in switch. This lets you easily turn the stick on and off without needing to unplug the battery. 
3. You can hot glue a mini breadboard to the bottom of the stick to make it easier to mount the ultrasonic sensor. Be careful with the orientation of the rows/columns in your mini breadboard. Make sure you do not put the ultrasonic sensor's pins all in the same set of holes where they will be short-circuited together. 
4. You will need to cut longer pieces of jumper wire to run between the ultrasonic sensor and the main breadboard. 

Image Credit: Ben Finio / Science Buddies

Figure 4. Breadboard, Arduino, switch, and 9V battery mounted to the handle of the stick.

Image Credit: Ben Finio / Science Buddies

Figure 5. Close-up view of the ultrasonic sensor in the mini breadboard. Note the orientation of the lines on the breadboard (connections may vary depending on where you buy your mini breadboard).

Image Credit: Ben Finio / Science Buddies

Figure 6. A zoomed-out view of the entire walking stick, with long wires zip-tied to the stick connecting the ultrasonic sensor to the main breadboard.

Test the Walking Stick

Once you have the prototype built, it is time for some real-world testing! Remember that the engineering design process is iterative. It is OK if your design does not work perfectly on the first try - you can always change it and make improvements. 

1. Test it yourself to make sure the ultrasonic sensor and buzzer are still working properly.
2. If it does not work, double-check that all your connections to the ultrasonic sensor are secure and that the ultrasonic sensor pins are not short-circuited together in the mini breadboard. If you are not sure, you can try rotating the sensor by 90 degrees in the breadboard to test this.
3. Detecting obstacles with the stick is different from waving your hand in front of the sensor. Revisit the threshold and buzzerDelayMin/Max variables, adjusting them if needed. What values provide the best overall combination of adequate warning without unnecessary beeping?
4. If possible, ask blind or visually impaired people to test your stick for you. Ask for their feedback. Can you incorporate it into an improved version of your design?

See the Variations section for more ideas about other features you could add to your project.

Ask an Expert

Do you have specific questions about your science project? Our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.

Post a Question

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 Reduced Inequalities: Reduce inequality within and among countries.

Variations

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