Accuracy analysis of a multi-loop linkage with joint clearances

This paper introduces a generalized method for error analysis of multi-loop mechanisms with joint clearance. Joint clearance is treated as a virtual link to simplify the study. Equivalent kinematical pair is used to model the motion freedoms furnished by the joint clearances. The developed methodology uses the properties of reciprocal screws to determine the instantaneous configurations. Six-bar linkages with different specified input links are taken as examples. Positioning error with joint clearance is compared with that of the ideal mechanism. The joint contact jump point configuration under the influence of transmission wrench screw is identified, and it is not always at the conventional jump point (stationary) configuration of the mechanism. The method is derived based on the static equilibrium state of the linkage.