A Design Method for Four-bar Mechanisms with Variable Speeds and Length-adjustable Driving Links

This paper proposes a design method to improve or obtain the desired output motion characteristics of single degree-of-freedom (DOF) Four-bar mechanisms by varying the speed trajectory and the length of the input link. This approach adds a ternary link to the original mechanism. The ternary link is adjacent to the input link, roller link, and connecting link, and makes use of a sliding pair, revolute pair, and revolute pair, respectively. The roller link, which is adjacent to the ternary link and fixed link by a revolute pair and a rolling pair, is guided by a designed slot embedded in the fixed link while the input link is driven by a servomotor with a specific speed trajectory. A Bezier curve is applied to determine the input speed trajectory and contour of the guiding slot. Examples are given to verify the feasibility and effectiveness of this work.

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