Underwater, emperor penguins can turn into regular rockets, accelerating from 0 to 7 m/s in less than a second. Researchers at the University of Applied Sciences Western Switzerland have created a new propulsion system based on a penguin’s shoulder and wing system that features a spherical joint mechanism enabling three degrees of freedom and a fixed center of rotation. Unlike an animal shoulder joint, the spherical joint enables unlimited rotational range about the main shaft axis like a propeller.
To achieve this, the researchers needed to overcome the technical challenges of spherical joints, such as the lack of rigidity and the inability to generate high torques. The researchers maneuvered around these challenges by choosing a parallel robotic architecture for this type of mechanism, because it enables rigidity as well as high actuation frequencies and amplitudes.
Because the motors are fixed, inertial forces are lower than for a serial robotic mechanism, such as a multi-joint arm. The resulting spherical parallel mechanism with coaxial shafts was designed and manufactured with these specifications: a fixed center of rotation (spherical joint), a working frequency of ~2.5 Hz under charge, an unlimited rotation about the main axis, and an arbitrary motion within a cone of +/-60°.”
