Smart Power Rack Automates Spotting Duties

When lifting weights, it’s a good idea to have a spotter in case you can’t actually do that one extra rep. As an alternative, fitness hacker and self-described poor student “Strangely Amusing” decided to build an Arduino-based auto rack mechanism to provide a helping hand when needed. His requirements for the system included being able to catch weight faster than a spotter, cheap to build, safe, and capable of handling techniques such as a clean and press.

The rather massive frame of this mechanism is built out of 2x4s and 4x4 beams that support a pair of straps to catch the weight bar when needed. These straps are attached to a braking wheel mechanism, which is configured in such a way that a counter-weight rolls the strap up when lifted, like an automotive seat belt. When the weight is dropped, the brake — which is applied by default — is released, locking straps in place.

An Arduino Uno running on a 12V battery controls the system, and user input is via a force sensor wrapped around the bar. If not gripped, the release disengages, allowing the user to trigger things when he or she realizes that things aren’t working — or if things simply slip.

While it’s an interesting design, it would certainly still a good idea to have others around when lifting, just in case something doesn’t work quite correctly. Check out the build in the video below…