Design of a Controlled-Stiffness Flexure Mechanism Based on the FACT Method

In complex environments such as minimally invasive surgery, mine disaster and earthquake relief, compared with the traditional rigid mechanism, variable stiffness mechanism has tremendous advantages. In this paper, a novel controlled-stiffness mechanism based on flexure element and structural constraints is proposed. The mechanism is a parallel mechanism with two branches, one of which contains a flexure element. The stiffness control of the mechanism is realized by controlling the functional direction of the flexible element. Using the traditional Grubler-Kutzbach (G-K) formula to calculate the degree of freedom (DOF) of the mechanism is difficult. In this paper, a method of freedom and constraint topology (FACT) method is introduced. This method has the advantages of visualization, simplicity, rapidity and is suitable for the analysis of DOF and motion ability of complex mechanisms. The analysis results show that the structure can realize the desired form of motion.