Dimensional synthesis of a 5-DOF hybrid robot

Combining the characteristics of parallel and series robots, hybrid robot has a good application prospect of machining. The dimensional synthesis, which is highly related to the performance, is studied based on a 5-DOF hybrid robot in this paper. The construction methods of optimization objectives which better reflect the motion range, stiffness and the kinematics performance are proposed. The bounding box theory is introduced to construct indexes of the actual motion ranges while considering the motion interference caused by mechanisms. And the maximum and minimum stiffness indexes of parallel structure based on the modified stiffness model and the comprehensive kinematics performance index based on condition number are also designed. Four constraints including installation, joint motion limitation, joint load limitation and validity of data define the feasible region. It is found from the optimization results that motion range changes more greatly than other objectives, which makes the solution with better motion ranges a higher priority. The correlation between dimensional parameters and optimization objectives is analyzed to guide the improvement of optimization model and provide references for dimensional synthesis of other hybrid robots. (C) 2020 Elsevier Ltd. All rights reserved.