Investigation of mechanical error in four-bar mechanism under the effects of link tolerance

Many planar manipulators are composed of a basic four-bar mechanism. The output delivered by the mechanism deviates from desired one due to factors like link tolerances. The performance needs to be characterized for satisfactory application. This article presents investigation of mechanical error in four-bar mechanism with revolute joints (4R) under the influence of link tolerance. The classical partial derivative formulation (PDA) in uncertainty analysis technique is primarily used for estimating the mechanical error. The error estimation is carried out with proposed modification in PDA formulation. A geometric approach is also developed to estimate the mechanical error for 4R configuration. The mechanical error obtained through PDA is verified using geometric approach. The generalized formulation is demonstrated, and comparative estimation is presented. The methods and conclusions proposed herewith are adaptable for other planar configurations.