Abstract
The formulas for displacement and velocity analyses are derived for the RSCR spatial four-link mechanism and the velocity of the coupler link is geometrically determined by instantaneous screw axes.The condition for limit positions of the driving-link motion is obtained on the basis of the force transmissibility from the coupler link to the driven link and the deteminant, which is composed of the coefficients of simultaneous equations for velocity analyses.By geometrically investigating the conditional function, a quantity is proposed in order to evaluate motion and force transmission characteristics.The parts of the functional relationship between input and output angles divided by the limit positions of the driving link, which are called branches and correspond to the composition loops of the mechanism, are identified by means of two newly established rules.
