Rombi is an innovative mobile scarecrow using an old iRobot Roomba 561, ESP32 Arduino board, and custom-made sensors to autonomously detect and repel birds (or other animals) from a balcony (or other spaces).
It has been tested as an effective repel system, animal and environmentally friendly solution.
Developing this has been a true pleasure. I also improved my hardware and software skills, learned optical and RF sensors, used CAD for 3D printing / PCB editing and applied image processing techniques for the first time.
Lastly, I didn’t forget my cybersecurity roots, so I embedded several hidden security protections and alerts in the esp32 server code to prevent hackers from remotely exploiting it.
While organizing the storage room, I came across an old Roomba iRobot 561 that had been lying on the floor for months because we hadn’t decided what to do with it.
It was in good working order, with a strong battery, but we had stopped using it. With young children in the house, the floor was often cluttered with toys, and having to clear the space every time before running the Roomba wasn’t always convenient. Over time, we reverted to using the regular vacuum cleaner.
On the other hand, it seemed a shame to leave it unused in the storage room. It was in excellent condition, so it would be better to either use it or donate it.
As I continued organizing, I began brainstorming various ideas that might be suitable for this Roomba. When I stepped out of the storage room, I noticed the floor was dirty with bird droppings.
And so, the first practical prototype was born. A combination of an autonomous, motorized, intelligent platform capable of patroling, avoiding obstacles, and autonomously returning to its docking station a long with a large balcony plagued by various birds that dig into the plants and leave behind a lot of mess and clutter.
To test whether birds are afraid of my mobile scarecrow, I built a human-shaped body out of Styrofoam, to which I attached a printer picture of an owl. I made the eyes more intimidating by using shiny black marbles. I placed this figure on the Roomba using a mount that can be easily disassembled.
I waited for the birds to come and activated the Roomba to start moving around. This scarecrow turned out to be highly effective, as the birds flew away as soon as it started moving, even before it got close to them. Even those perched on the pergola above weren't indifferent and flew off to a nearby building.
The experiment was a success, and I moved on to the improvement phase. Since there's no need for the Roomba to vacuum the balcony while it's moving around because vacuuming consumes energy that I need to conserve for its patrols, I completely dismantled it and gently removed the parts related to vacuuming.
Now, the Roomba is lighter, which significantly saves energy, increasing its operational time. Occasionally, I left the Roomba on the balcony, letting it move around with only the original "schedule" feature which was built into this model.
Due to the size of the balcony, each round of the Roomba took about 35 minutes. The moving scarecrow immediately scared the birds away, and they didn't return as long as the Roomba was active.
The only thing left was to figure out when to activate the Roomba, once a day isn't enough. This Roomba model doesn't have Wi-Fi for remote control and can only perform one scheduled "patrol" a day, so some sensor development and remote-control capabilities need to be added.
I delved into researching the model and discovered that the Roomba has a dedicated serial protocol called the Open Interface (OI), which allows for far more operations than the buttons on the top of the device. To experiment with this, I needed an Arduino board, logic level converters (since the Roomba operates at TTL voltage levels, i.e., 0-5 volts), and DC-DC converters (the Roomba's battery is 20V).
I assembled an ESP32 on a breadboard, along with some voltage converters, and prepared a set of HEX commands in Roomba’s language using the OI protocol. For example:
Stop (128) (131) (137)
Shutdown (128) (131) (133)
Start (128) (131) (135)
And it worked.
It’s possible to execute dozens of commands, from starting and stopping the Roomba to full control over its sensors, wheels, and speed, all via the Arduino board. Once I had the Arduino in place, it was a short step to adding a Web Server that allowed connection to the controller via WiFi.
It works excellently when connected to the same Wi-Fi network. But sometimes it’s necessary to connect from outside the Wi-Fi range if you wish to operate it remotely. A few additional lines of code were added, and my digital scarecrow now supports remote commands control through a Telegram bot, providing responses and status updates.
I can even get a real time video from the Roomba's patrol. The current version supports the following commands via the Web Server and Telegram:
- Start patrol
- Return to docking station
- Remote Camera on/off
- LED lighting control
- Send status reports, such as temperature and battery voltage.
The Roomba works excellently both remotely and up close when I initiate an action, but now it’s time for it to gain some autonomy. The Roomba will need to spring into action whenever birds are on the balcony and occasionally even when they aren’t, as some birds, like mynas and pigeons, observe from a distance before deciding to land on the balcony.
It’s time to detect birds on the balcony and automatically activate the Roomba. In most cases, the birds first land on the railing or pergola before descending to the floor. I explored several methods and sensors suitable for different surfaces.
I won’t go into too much detail about all the sensors I built, but using a simple optical sensor based on a laser break-beam, proved to be the most effective and reliable for the railing. For the pergola, to avoid false alarms from every bird flying by, metal spikes (type W) needed to be used. For the floor, detection is handled by a camera with image processing (I used the efficient libraries from eloquentarduino).
I placed the laser break-beam sensors about 3 cm above the railing, to detect various types of birds. When a bird stands or passes over the railing, it breaks the laser beam, sending a signal to the Roomba to start its patrol.
I mounted the cameras at a high position on the wall aimed to the floor to avoid false alarms from open areas and only focus on where the birds land. Each camera easily covers a floor area of about 5 x 3 meters for a reliable detection. If detection is needed at night, strong lighting, such as IR, is required.
The sensors are Arduino-based and communicate directly with the web server within the Roomba, all connected to the same Wi-Fi network.
FastDocking.mp4
This mobile scarecrow is far more efficient than any static solutions I have ever tried. It’s harmless to both the birds and the environment. While birds may become accustomed to various scarecrow, reflectors and chains, they don’t remain indifferent when confronted by an owl with dark eyes approaching them in an unusual manner.
And, of course, there’s a bonus. Implementing this idea allows me to learn more about Arduino hardware and software, image processing, PCB design, CAD software, sensor design and much more. It’s pure enjoyment.
- Virtual Wall was used to prevent the Roomba from attempting to enter the house.
- Several security protections was embedded in the Roomba server code to prevent hackers from connecting.
- Small mirrors were placed along the railing to maintain one laser source.
- The complete code for the sensors and the main board will be uploaded in the future.
- A hollow body (e.g., made of metal mesh) for the scarecrow boady to make it less sensitive to strong winds.
- Sending the Roomba directly to the sensor area from which the alert was triggered.
- Adjusting the Roomba's travel path based on the shape and size of the balcony.