Meccanica (2011) 46:771–784 DOI 10.1007/s11012-010-9336-6 A statically balanced SCARA-like industrial manipulator with high energetic efficiency Luca Bruzzone · Giorgio Bozzini Received: 3 February 2009 / Accepted: 2 July 2010 / Published online: 3 August 2010 © Springer Science+Business Media B.V. 2010 Abstract The purpose of the work is the improve- ment 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 de- signed. It is derived from a RRPR SCARA by substi- tuting 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 kine- matic and dynamic models of the manipulator are de- scribed. Using these models, different typical pick-and- place 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 bal- ancing 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 ro- bot 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 L. Bruzzone ( ) · G. Bozzini PMARlab—DIMEC, University of Genoa, Via All’Opera Pia 15A, 16145 Genoa, Italy e-mail: bruzzone@dimec.unige.it G. Bozzini e-mail: bozzini@dimec.unige.it minimise the energy consumption, with potential eco- nomical and environmental benefits. Keywords Energetic efficiency · Static balancing · Industrial robotics 1 Introduction The reduction of energy consumption in every field of human activity is probably one of the major challenges of the future; in particular, the improvement of the en- ergetic efficiency of robotized lines is an important is- sue to be considered by the researchers. Most industrial manipulators are serial robots, for their advantages in terms of operative flexibility and workspace size with respect to parallel robots. In ser- ial robots the ratio between payload mass and overall moving mass is low; therefore, most part of the electri- cal energy consumption of the robot actuators is used to overcome the inertial forces and the gravity forces acting on the robot links [1]. This degrades the dy- namic performance and the ability to resist external forces, and large amounts of power are consumed in resisting gravitational forces even in static conditions. The energetic efficiency of a serial manipulator can be improved by means of the static balancing [1, 2]: if a robot is statically balanced, the energy necessary to overcome the gravity forces acting on the links is null, and the actuators are loaded only by the inertial forces and by the payload.