OpenCV Object Tracking and Pan/Tilt Servo Control

Package Dependencies

Using the pysearchimages Raspbian distro (which has OpenCV 3.2 bundled), install the required Python packages with:

source start_py2cv3.sh
pip install --upgrade pip
pip install -r pip/requirements.txt
sudo -H pip install arc852-robotics --extra-index-url https://pypi.fury.io/pambrose/

Info on arc852-robotics is here.

Color Picker

color_picker.py is used to choose a target BGR value.

Usage

$ ./color_picker.py 

CLI Options

Option	Description	Default
-u, --usb	Use USB Raspi camera	false
-w, --width	Image width	400
--display	Display image	false
-x, --flipx	Flip image on X axis	false
-y, --flipy	Flip image on Y axis	false
--http	HTTP hostname:port	localhost:8080
--delay	HTTP delay secs	0.25
-i, --file	HTTP template file
--verbose-http	Enable verbose HTTP log	false
-v, --verbose	Enable debugging output	false
-h, --help	Summary of options

Display Keystrokes

Keystroke	Action
c	Print current BGR value to console
k	Move ROI up
j	Move ROI down
h	Move ROI left
k	Move ROI right
-	Decrease ROI size
+	Increase ROI size
<	Decrease image size
>	Increase image size
r	Reset ROI size and image size
q	Quit

Single Object Tracker

The object_tracker.py script runs the LocationServer, which generates the location of the object having the target BGR value. It supplies data to clients like servo_controller.py via gRPC. The smaller the image width, the smaller the matching target area. Thus, decreasing the image width may require also decreasing the minimum target pixel area.

Usage

$ python single_object_tracker.py --bgr "174, 56, 5" --display 

CLI Options

Option	Description	Default
--bgr	BGR target value
-u, --usb	Use USB Raspi camera	false
-w, --width	Image width	400
-e, --percent	Middle percent	15
--min	Minimum target pixel area	100
--range	HSV Range	20
--leds	Enable Blinkt led feedback	false
--display	Display image	false
-x, --flipx	Flip image on X axis	false
-y, --flipy	Flip image on Y axis	false
-t, --http	HTTP hostname:port	localhost:8080
--delay	HTTP delay secs	0.25
-i, --file	HTTP template file
-p, --port	gRPC server port	50051
--verbose-http	Enable verbose HTTP log	false
-v, --verbose	Enable debugging output	false
-h, --help	Summary of options

Sample Image

Display Keystrokes

Keystroke	Action
-	Decrease center area
+	Increase center area
w	Decrease image size
W	Increase image size
r	Reset center area and image size
s	Save current image to disk
q	Quit

FirmataServo Controller

The firmata_controller.py script reads the location values provided by single_object_tracker.py and adjusts the pan/tilt servos accordingly.

Usage

$ firmata_controller.py --port ttyACM0 --grpc localhost

CLI Options

Option	Description	Default
-s, --serial	Arduino serial port	ttyACM0
-g, --grpc	Object Tracker gRPC server hostname
-x, --xservo	X servo PWM pin	5
-y, --xyservo	Y servo PWM pin	6
--calib	Calibration mode	false
-v, --verbose	Enable debugging output	false
-h, --help	Summary of options

Relevant Links

Hardware

• Raspberry Pi Camera
• Pan/Tilt Kit
• Blinkt

Software

• pyfirmata
• gRPC
• OpenCV
• Plot.ly

Instructions on how to display Raspi OpenCV camera images on a Mac are here