Is the Annin AR4 the Workhorse Robot Arm for You?

It’s no secret that makers love robots, but many of us tend to focus on superficial qualities or cost over the potential for real work. My first robot, a line-follower that I built when I was 12, was great for learning soldering and dipping my toes into robotics, but it wasn’t useful. I’m willing to bet that was true for your first robot, too. If you’re ready to step up to a real robot that can do real work, the Annin Robotics AR4 may be ideal and Thomas Sanladerer built one to evaluate.

The AR4 is a 6DOF robot arm meant to fit somewhere in the middle on a scale between cheap “toy” robots and wildly expensive industrial robots. It is an open source design created by Chris Annin for hobbyists, schools, and small businesses. Sanladerer estimated that it costs about $2,000 to build, but that cost will vary dramatically based on part sourcing.

While that is far more affordable than the “real” commercial robots on the market, it certainly isn’t a trivial amount of money and Sanladerer wanted to find out if the AR4 is worth the cost. He purchased a complete AR4 MK3 combo kit and a servo gripper parts kit from Annin Robotics, as well as the stepper motor kit from Stepperonline.

Sanladerer’s feelings about the build process were mixed. The parts — including the CNC-machined parts included in the kit from Annin Robotics — were made well, but there were often engineering choices made that would make professionals raise their eyebrows. One example that Sanladerer found was instances of grub screws pushing into bearing race surfaces. Another was the use of directly soldered connections instead of connectors. Those may be minor issues or they may be dealbreakers, depending on your perspective and needs.

The testing after assembly seemed to reflect what Sanladerer found during the build. The AR4 does work and has some impressive capabilities for the price, but it also has flaws. Despite design choices intended to reduce it, the robot experiences significant backlash. And though there are encoders in each joint, closed-loop feedback isn’t implemented in the firmware. The result is disappointing accuracy and repeatability.

That said, Sanladerer was impressed with the software, which works with the robot’s Teensy 4.1 and Arduino Nano controllers. He says it was intuitive and powerful, with plenty of potential for a variety of tasks. But jittery movement made it difficult to use in some situations, such as moving a camera to capture dynamic shots.

If this robot interests you, then you’ll want to watch Sanladerer’s full video to get all the details. This is the kind of evaluation that requires more nuance than a typical consumer product, but the Annin AR4 is certainly intriguing.