This episode explores the surprising homogeneity in humanoid robot shoulder designs, despite the diverse design space available. Against the backdrop of a review of hip designs, where a consensus on the FAR (Flexion-Abduction-Rotation) configuration exists, the discussion pivots to the shoulder, revealing an almost universal adoption of the same FAR structure. More significantly, the podcast investigates the exceptions to this trend, such as Agility's initial RFR (Rotation-Flexion-Rotation) design and Aptronic's unique all-linear-actuator approach (ARF). For instance, Agility's later shift back to FAR highlights the industry's preference for established configurations. The conversation delves into the reasons behind this preference, including the challenges of singularity avoidance and the benefits of dihedral angles in optimizing range of motion. Ultimately, the episode concludes by proposing alternative shoulder designs inspired by industrial robot wrists, suggesting that a re-evaluation of existing robotic mechanisms could lead to innovations in humanoid robot design, impacting the efficiency, dexterity, and safety of future robots.
