Okay, so I’ve been messing around with this idea of tracking how many people come in and out of different areas in a hospital. You know, like a foot traffic counter. It’s not as straightforward as you might think!
I started by thinking, “Hey, I can just use a simple sensor, right?” I grabbed one of those infrared beam break sensors – the kind you see in some stores. My first thought was to put it at the entrance of a hallway.
Initial Setup
- Sensor: Basic infrared beam break sensor.
- Location: Entrance of a test hallway.
- Idea: Every time the beam breaks, it’s a person. Add one to the count.
I wired it up to a little Arduino board I had lying around. Wrote a super simple code to just increment a counter every time the beam was broken. Seemed easy enough.
But… it was immediately obvious this wasn’t going to work. Two people walking side-by-side? One count. Someone walks in, then pauses, then walks back out? Two counts, or maybe even more if they wave their arms around! It was a mess. The numbers were way off.
So, back to the drawing board. I needed something a bit smarter. I started looking into those thermal cameras. You know, the ones that show heat signatures? My thinking was, I could use that to detect people more accurately, even if they’re close together.
Thermal Camera Testing
- Sensor: A cheap thermal camera module I found online.
- Processing: Connected it to a Raspberry Pi this time.
- Idea: Use some basic image processing to identify “blobs” of heat and count those.
This was… trickier. I had to learn a bit about image processing libraries for the Raspberry Pi. I used it to look for warm areas and count them. It worked… okay. It was definitely better than the beam break sensor, but it still had problems.
Sometimes it would count a single person as two if they were carrying something warm, like a hot cup of coffee. Other times, it would miss people if they were wearing a heavy coat and it was cold in the hallway. And bright sunlight? Forget about it. The readings went all crazy.
I realized I needed a way to tell the direction people were moving. That’s when I started thinking about using two sensors, spaced a little bit apart.
Dual Sensor Approach
- Sensors: Two of the original infrared beam break sensors.
- Placement: Installed them about a foot apart at the hallway entrance.
- Idea:By checking to find which sensor is triggered firstly,we can find which direction people were moving in.
I went back to the simpler beam-break sensors, because I figured if I could get the direction right, the simpler setup would be more reliable. This new setup help us a lot.
This was much better. I rewrote the code to track which sensor broke first, and then only increment the counter if the second sensor broke in the expected sequence. It could now tell if someone was entering or exiting!
It’s still not perfect, of course. If two people walk really close together, it might still mess up. But it’s a huge improvement. I’m thinking of adding a little display to show the current count, and maybe even logging the data to a file so I can see traffic patterns over time. That’s next on my to-do list!