Build a Person Detection Security Robot That Sends You a Photo of the Person Stealing Your Chocolates

In this tutorial you will create a desk security system with no hardware other than your laptop and built-in webcam.

Maybe you keep a box of chocolates on your desk to snack on when you are hungry. Maybe someone is eating your chocolates when you are away. You’re not sure who, but you suspect Steve. This robot will help you catch the culprit.

When someone comes to your desk, the robot will use the Vision Service and an ML model to detect a person, take their photo, and text you an alert with a photo of the person.

Text message reading “Alert There is someone at your desk beware” with a photo of a person (Steve) detected by the camera as he approaches the desk.

Hardware requirements

You need the following hardware for this tutorial:

  • Computer with a webcam
    • This tutorial uses a MacBook Pro but any computer running macOS or 64-bit Linux will work
  • Mobile phone (to receive the text messages)

Software requirements

You will use the following software in this tutorial:

Configure your robot on the Viam app

If you followed the Use Object Detection to Turn Your Lights On tutorial, you already have a robot set up on the Viam app, connected and live, with a webcam configured.

If you're starting with this tutorial, click here for instructions.

How to use yagmail

Install yagmail (Yet Another Gmail/SMTP client) by running the following command in a terminal on your computer:

pip3 install yagmail

Then we have to indicate whom to send a message to, the subject, and the contents of the text message (which can be a string, image or audio). Example code below (though you don’t have to use it yet, this will get used in the next section):

yag.send('', 'subject', contents)

You will need to access to your phone number through your carrier. For this tutorial, you are going to send the text to yourself. You will replace with your phone number and SMS gateway address. You can find yours here: Gateway Addresses for Mobile Phone Carrier Text Message. Some common ones:

  • AT&T:
  • Verizon Wireless:

As an example, if you have T-Mobile your code will look like this:

yag.send('', 'subject', contents)

This allows us to route the email to our phone as a text message.

Use the Viam Python SDK to control your security robot

If you followed the Use Object Detection to Turn Your Lights On tutorial, you already set up a folder with some Python code that connects to your robot and implements the Vision Service.

If you are starting with this tutorial, follow the steps here to create the main script file, connect the code to the robot, and select the model and label path. Ignore the step about the Kasa smart plug host address.

Instead of using this person detector to activate a smart plug, you will send yourself a text message.

Make a copy of the file in your project directory and save it as You will use the same robot connection code and Vision Service configuration code but edit some other parts of the file.

Delete the from kasa import Discover, SmartPlug line and replace it with the following to import the Yagmail Python library:

import yagmail

Now you need to rewrite the if/else function. If a person is detected, your robot will print sending a message, take a photo, and save it to your computer as foundyou.png (or whatever name you want).

Then you will create a yagmail.SMTP instance to initialize the server connection.

Refer to the code below and the yagmail instructions to edit your file as necessary.

Click to show the full example code.

Save your code file.

Run the code

You are ready to test your robot!

From a command line on your computer, navigate to the project directory and run the code with this command:


If you are in front of your computer’s webcam, you should get a text!

Your terminal should look like this as your project runs if you are in front of the camera for a bit, and then move away from the screen:

This is a person!
sending message
x_min: 7
y_min: 0
x_max: 543
y_max: 480
confidence: 0.94140625
class_name: "Person"

This is a person!
sending message
x_min: 51
y_min: 0
x_max: 588
y_max: 480
confidence: 0.9375
class_name: "Person"

This is a person!
sending message
There's nobody here, don't send message
There's nobody here, don't send message

Summary and next steps

In this tutorial, you learned how to build a security robot using the Vision Service, your computer, and your mobile phone, and we all learned not to trust Steve.

Have you heard about the chocolate box thief? He’s always got a few Twix up his Steve.

For more robotics projects, check out our other tutorials.

You can also ask questions in the Community Discord and we will be happy to help.

Have questions, or want to meet other people working on robots? Join our Community Discord.