Theoretical and Numerical Analysis of Jamming Phenomenon in Positioning of Circular Workpiece on Horizontal Surface

Grasping or positioning workpiece with circular geometry is a common process in fixture design and robotic manipulation systems. The typical two-contact mechanisms that are usually used for gripping or positioning of these kinds of workpieces are prone to jam. Determination of the conditions in which jamming occurs in such systems seems to be necessary for research purposes as well as industrial applications. In the present study, jamming of the workpiece with the circular cross-section is investigated during its positioning on the horizontal surface. The theoretical foundation is established based on two models as far as the force equilibrium equations and the minimum norm principle. Validation of the theoretical predictions is conducted through the numerical analysis in the Adams software. The distance that the workpiece should travel to jam is obtained from the numerical analysis and compared to the theoretical predictions. By assuming the coefficient of friction equal to 0.4 and the radius of the workpiece equal to 10mm, jamming-in travel of the workpiece was obtained as 24.38mm and 25.58mm from the theoretical models and numerical analysis, respectively. A relative error of 4.9% is obtained between the theoretical predictions and numerical results. This value indicates the accuracy of predictions of the suggested theoretical models and the credibility of their results.