Archive: People Counter - Heads first electronics

People Counter was a project for creating a pedestrian counting sensor and a large format display to show the results over a day.

This included the design of custom PCBs and enclosures for the purpose. Both devices (counter and sensor) used off the shelf development boards (Feather adalogger and Teensy 3.2 respectively)



It was also part of the design process to create a modular assembly for 7 segment screens, with the intent of being able to use it as base for a creation of a 7 segment matrix capable of displaying graphics.



In this case the 7 segment PCB was build to be modular. It has links for SPI and power on the X direction and I2C in the Y. This way it could be assembled in a X*Y panel with one Teensy per row and I2C to control the overall matrix. Using a microcontroller for each row would mean it is possible to keep high refresh rate needed for displaying the graphics.

The project is finished as is and links for the sensor and screen development including the enclosure design, PCB and code are available on Github.

Development will be continued pursuing a graphics based version



EDIT: Specification

This is a post post. I thought it would be important to clarify the project specification in the case. The following are excerpts from the project description document

(…) It should be able to count people walking past independently of direction to a range of 5 meters.



A PIR sensor detect changes in light and for this reason might not be allow to detect groups of people that walk together. The people counter will not have any user interface.

A second part of the system will be a display for the count number, the two systems are independent and connected through a custom designed cable (up to 5 meters long).

Further

· We could make the people counter work of computer vision. Ideally this would have the camera to be placed directly over the path. The counter would be more precise and able to handle groups of people. Solutions like these are employed regularly in cities. However this would change the needs in computer power

NOTES

Efficiency and reliability of the system may vary depending actual operating conditions:



1) Detecting heat sources other than the human body, such as

(1) Small animals entering the detection area.

(2) When a heat source for example sunlight, incandescent light, car headlights etc, or strong light beam hit the sensor regardless inside or outside the detection area.

(3) Sudden temperature change inside or around the detection area caused by hot or cold wind from HVAC, or vapor from the humidifier, etc.



2) Difficulty in sensing the heat source(1) Glass, acrylic or similar materials standing between the target and the sensor may not allow a correct transmission of infrared rays.