There are probably at least as many ways to construct a robotic arm as there are uses for them. In the case of [Thomas Sanladerer] his primary requirement for the robotic arm was to support a digital camera, which apparently has to be capable of looking vaguely menacing in a completely casual manner. Meet Caroline, whose styling and color scheme is completely coincidental and does not promise yummy moist cake for anyone who is still alive after all experiments have been run.
Unlike typical robotic arms where each joint in the arm is directly driven by a stepper motor or similar, [Thomas] opted to use a linear rail that pushes or pulls the next section of the arm in a manner that’s reminiscent of the action by the opposing muscles in our mammalian appendages. This 3D printer-inspired design is pretty sturdy, but the steppers like to skip steps, so he is considering replacing them with brushless motors.
Beyond this, the rest of the robotic arm uses aluminium hollow stock, a lot of 3D printed sections and for the head a bunch of Waveshare ST3215 servos with internal magnetic encoder for angle control. One of these ~€35 ST3215s did cook itself during testing, which is somewhat worrying. Overall, total costs was a few hundred Euro, which for a nine-degree robotic arm like this isn’t too terrible.