Dynamic synthesis of a planar slider-crank mechanism with clearances

In practice, clearances in the joints are inevitable due to tolerances, and defects arising from design and manufacturing. It is noteworthy that in the presence of clearance at a joint, a mechanism gains some additional, uncontrollable degrees of freedom which are the source of error. Moreover, joints undergo wear and backlashes and so cannot be used in precision mechanisms. In this paper, an optimization method is proposed to alleviate the undesirable effects of joint clearances. The main consideration here is to optimize the mass distribution of links of a mechanism to reduce or eliminate the impact forces in the clearance joints. An algorithm based on PSO solves this highly nonlinear optimization problem for a slider-crank mechanism with revolute clearance joints. Finally, an example is included to demonstrate the efficiency of the algorithm. The results clearly reveal that the linear and angular accelerations of the links and the contact forces in the optimal design are very smooth and bounded.