Joint efforts - How to simulate a shoulder

With a click and a sound, the machine starts moving. A light is glowing on one of the modules, signaling that it is ready to operate. Slowly it turns to the front, twists a bit and then moves backwards again. The movements remind of those of our arms, swinging back and forth, changing only by a few little jabs on the control stick. What sounds like a futuristic robot is actually a machine built for the research group of Daniel Smolen to test artificial shoulder joints in various projects of the shoulder team.