The research of structure parameter optimization process for a novel parallel radiotherapy bed

In order to guarantee the preoperative and intraoperative precise positioning demand of the radiotherapy bed in the radiation process, utilizing the advantages of parallel mechanism, in this paper, a parallel structure radiotherapy bed was designed to meet the demands of high positioning precision, high stiffness, high carrying capacity and flexible configuration space which could cover the shortage of the conventional radiotherapy bed. Firstly, this paper analyzed the precise workspace of the radiotherapy bed with kinematics inverse solved by vector algebra method and studied the influence of workspace by changing the rule of all parameters as well as finding the relationships between them in the condition that the size of the moving platform and the fixed platform were limited. Then, in order to meet the requirements of stability and security of the radiotherapy bed, considering the workspace and the forces on it, a new parameter optimization process was proposed with constructing the objective function of the Jacobian matrix condition number, the universe average of condition number and the fluctuation of condition number. The simulation analysis results demonstrated that the overall performance of the radiotherapy bed was considerably improved with the smaller dimensions of the radiotherapy bed, the significantly reduced forces on the structure in the workspace and the smaller condition number of Jacobian matrix with uniform distribution in the whole workspace.