Modeling of a Braced Robot with Four-Bar Mechanism

Kinematic analysis of a braced robot is described. The strategy of bracing is intended for absolute robot end-point pose accuracy and repetability improvement. The principle of mechanical lever is explained with the theoretical point-to-line contact-type of robot bracing. The kinematics of braced robot with true surface-to-surface contact-type are derived: 1) with the local surface geometry of contacting bodies, 2) by an original method of constructing an equivalent four-bar mechanism. Pose uncertainty due to inaccuracy and repetability of free and braced robot is analyzed. An estimation function of accuracy improvement by bracing together with simulation results are presented. Advantages and disadvantages of the proposed method of equivalent four-bar mechanism with regard to the uncertainty reduction are discussed.