Wrench Whisperer

About this Project

Problem: My high school FIRST Robotics Competition Team had bins of unsorted allen wrenches that we had to sort through each time we needed an allen wrench.

Solution: I designed, built and programmed an automatic wrench measurer that quickly differentiates allen wrench sizes.

How does it work? The Wrench Whisperer uses computer vision techniques to precisely measure the size of an allen wrench placed on the light box. The secret is in the precision of the environment; the light box produces a perfect silhouette, and camera exposure settings are fixed to ensure consistent measurements. Once precision is obtained, accuracy is just a calibration curve away.

Specs

• 0.1mm accuracy
• <0.5s measure time
• 0.5mm min wrench size

Relevant Skills

• Sensor calibration techniques: achieved 0.1mm precision with HD webcam using precise construction and a lookup table
• Computer vision: Standardized exposure, cropped, blurred, thresholded, detected contours, measured areas, detected orientation of input image using OpenCV and Python
• Frame design: ... out of Legos! But was precise and rigid enough to transport and consistently measure 0.1mm accuracy
• Iterative design: Evaluated and redesigned, used Git for version control