An optimum design method for a new deployable mechanism in scissors bridge

In order to solve the existing problems of driving cylinder failures of a new deployable mechanism of scissors bridge in the process of an engineering prototype test, a multiobjective optimal model was proposed. The minimum cylinder pushing force and pulling force are taken as the optimization objective. The location of hinge points is taken as variables. Considering the unfolding of the scissor bridge as a quasi-static process, the kinematics model and statics model of the deployable mechanism were constructed using Denavit-Hatenberg homogeneous transformed matrix and mechanics equilibrium conditions, respectively. The proposed optimization strategy was employed based on Pareto optimum, and Pareto frontier was obtained by varying weight coefficient of multiobjective within interval around the required value. Using the trust region algorithm to solve optimization model, a reasonable solution was chosen from Pareto frontier. The results showed that the force conditions of the hydraulic cylinder, key hinge points and linkage in the deployable mechanism were significantly improved through a comparative study between initial design and optimized design for the engineering prototype. The research has shown that the optimization method has quick convergence speed and steady performance. The correctness of the optimal model and mechanics model was proved by ADAMS simulation. This passage provides new ideas and solutions for the force optimization of deployable mechanism of engineering prototype.