A statically balanced SCARA-like industrial manipulator with high energetic efficiency

摘要

The purpose of the work is the improvement of the energetic efficiency of automated lines assisted by four-degree-of-freedom serial robots with three translations and one rotation about a vertical axis (Schoenflies motion). A novel robotic architecture (BalArm) has been designed. It is derived from a RRPR SCARA by substituting a four-bar mechanism for the vertical prismatic joint, in order to balance statically the robot by means of a counter-weight or a torsional spring. The kinematic and dynamic models of the manipulator are described. Using these models, different typical pick-andplace operations have been simulated; the results show that for low-speed motions the mass balancing is more efficient, while for high-speed motions the elastic balancing is preferable; the advantage threshold depends on the task trajectory, speed and acceleration and on the preload of the elastic element. From a constructive point of view, the BalArm robot can be realized with modular solutions, in order to easily change the static balancing. This allows to adapt the balancing to the specific working cycle to minimise the energy consumption, with potential economical and environmental benefits.