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Chasing the object like in kickstarter video

Pixy Hardware
#1

I just received my pixy and pan/tilt servo kit. I managed to assemble the kit and get it to follow the object using by setting high D gains and low P gains for pan tilt.

Now I would like to build a mechanism like in the kickstarter demo video. Obviously it seems to be built using some lego components like wheels, gears apart from the regular pixy and pan/tilt kits. Has someone already built it? What are the additional components required and are there instructions?

If not, I would like to use the tilt servo motor to make the pixy chase objects, and leave pan servo as it since I think it needs to look around for the object and move forward in the direction of the object. For that, I will have to build a gear mechanism to connect the tilt servo to wheels. Is this a good idea? I will also have to change the code which generates the servo inputs for making it move forward rather than tilt. It may be easier to do it using arduino tiltLoop code change than FPGA code change of pixy. How to estimate distance of the object from the image? Will I need two pixies for this? How does the demo video achieve it?

Thanks in advance.

#2

Hi Kiran,

That robot was made by Rich, so I’ll see if he has any details he can easily share on how to make it or something similar. “Here”:http://cmucam.org/boards/9/topics/2898?r=3427#message-3427 Rich posted some of the code he used for that robot.

Connecting a single Pixy to a robot is definitely possible, as you saw in the video. Depending on your setup you may need to modify the Pixy firmware, but it may be easier for you to use an Arduino to communicate with the Pixy and other components of the robot.

A few other people on here have talked about determining distance from an image (“here”:http://cmucam.org/boards/8/topics/2915 is one example). If you don’t care about being exact, you could just measure the size of the object in the image at a few different distances and determine a rough formula for distance calculation based on your measurements.

Scott

#3

I implemented one for Adafruit based on the Pixy and the Pololu Zumo root base.
Full tutorial and source code can be found here: