Static balancing of parallel robots

In this paper, the static balancing of spatial parallel manipulator is addressed. Static balancing is defined as that the weight of the links does not produce any force at actuators for any configuration of the manipulator. In order to obtain the balancing condition, the position vector of the global center of the mass is expressed as a function of the position and orientation of the platform and of the six actuated prismatic joint. Then, the conditions for balancing are derived from the expressions obtained. Two methods lead to static balancing, namely using counterweight and using springs. In both methods, the resulting mechanism is fully balanced for gravity. In this study the first method is implemented, leading to the manipulator with a stationary global center of mass. (C) 2004 Elsevier Ltd. All rights reserved.