Decoupled Kinematics for Non-spherical Wrist Manipulators

Dynamically avoiding collision is one of the key challenges to enabling industrial collaborative manufacturing. These techniques guarantee the safety of the operators without disregarding manufacturing efficiency. However, as these techniques usually rely on the jacobian, they can move the robot towards singular configurations, blocking its movements and affecting performance and application safety momentaneously. This work proposes a novel technique, wrist spherification, to decouple the position and orientation of non-spherical wrist manipulators, enabling more efficient computation of online responses to dynamic obstacles. For such a purpose, the forward and inverse kinematics are proposed to address the position and velocity problems. The computational performance of the explicit inverse kinematics solutions proposed has been compared against the generic inverse kinematic solver of Matlab Robotics Toolbox based on Broyden-Fletcher-Goldfarb-Shanno (BFGS) gradient projection algorithm, reducing around five times the required mean computational time. A preliminary kinematic analysis is also presented, highlighting the kinematic improvement to compute offline singularities.