Inexpensive Robot Tracking System Is Swarm Ready


[Ladvien] has figured an inexpensive way to control a robot from a remote PC with a static webcam. Inspired by swarming robot videos such as those from the UPENN Grasp lab, [Ladvien] wanted to build his own static camera based system. He’s also managed to create one of the more eclectic Instructables we’ve seen. You don’t often find pseudo code for robot suicide mixed in with the project instructions.

Fixed cameras are used in many motion capture systems, such as the Vicon system used by numerous film, game, and animation studios. Vicon and similar systems cost tens of thousands of dollars. This was a bit outside [Ladvien’s] budget. He set about building his own system from scratch. The first step was the hardest – obtaining permission from his wife to screw a webcam into the ceiling. With that problem overcome, [Ladvien] brought openCV and python to bear. He created Overlord, his webcam vision and control system. A vision system with nothing to control would be rather boring, so [Ladvien] created DotMuncher, Overlord’s radio controlled robot slave.

The basic processing system is rather simple. DotMuncher carries a magnetometer on board, which it uses to send heading information to Overlord. Overlord is pre-calibrated with an offset from magnetic north to “video game north” (toward the top of the screen). Overlord then uses openCV’s color detection to find DotMuncher in the current scene.
Overlord finally generates a virtual “Dot” on screen, and directs DotMuncher to drive over to it. When the robot gets to the dot, it is considered munched, and a new dot is generated.

The whole system is a proof of concept for future swarm projects [Ladvien] has planned. He’s hoping to have autonomous robot tag working before the end of the year. We can’t wait to see that one.

4 thoughts on “Inexpensive Robot Tracking System Is Swarm Ready

  1. [Ladvien] has made some awesome progress! I love bots with character. Hopefully future progress leverages gazebo/player/stage so [Ladvien] doesn’t have to go reinventing the wheel. Go swarm Go!

  2. Ah cameras on windows.
    The camera interface on windows7 is pretty much in the XP or earlier stage, and I bet it’s the same with w8, some things just are not worked on at MS.
    It’s the one thing that necessitates you to actually log out or even reset/powercycle the damn computer when it gets stuck as a standard operating procedure.

  3. To auto-calibrate the video game north, he could make the robot move in a straight line for a bit and measure the start position and the end position in the webcam’s frame. With that information he could then determine the video game north based on the magnetic north he set while moving straight. The only problem would be the webcam’s spherical distortion, but that too can be overcome using OpenCV’s functionality.

    Just a thought.

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