Dynamic Comprehensive Design Of A Four-degree-of-freedom High-speed Parallel Mechanism With Double Drive Branches

In automated production lines in the medical,food,and logistics industries,four-degree-of-freedom high-speed parallel robots have been widely used.This subject researches a four-degree-of-freedom high-speed parallel mechanism with dual-drive branch chains and conducted in-depth research from mechanism innovation design,kinematics analysis,rigid body dynamics analysis,elastic dynamics analysis,and dynamic integrated design.First,two new types of dual-drive compound branch chains are proposed,and the branch chains are used in the configuration design of a four-degree-of-freedom high-speed parallel mechanism.The traditional degrees of freedom calculation method and simulation method are used to analyze the motion characteristics of the main and branch chain mechanisms.It also reveals the sufficient and necessary conditions for the three-dimensional translational movement of the main chain mechanism from the scale elements.Finally,the kinematic characteristics of the four-degree-of-freedom high-speed parallel mechanism are studied.According to the partial decoupling characteristics of the mechanism,the kinematics forward and reverse solution model of the four-degree-of-freedom high-speed parallel mechanism with double drive branches is established by the mechanism split method.The speed,acceleration,and the corresponding Jacobian matrix of the end effector are solved,and the model is verified through numerical analysis and kinematics simulation.A rigid body dynamics model of a four-degree-of-freedom high-speed parallel mechanism with dual drive branches is established by the virtual work principle method.A robot motion control system is constructed through the Simulink plug-in,and input the gate-shaped movement trajectory into the Simulink model of the mechanism to obtain the law of the change of the driving torque of each driving arm with the position of the end effector.The elastodynamic equations of a four-degree-of-freedom high-speed parallel mechanism with double drive branches are established by using the finite element method and the sub-structure method.The elastodynamic equations are used to solve the low-order natural frequencies,low-order natural modes,and output errors of the mechanism.Based on the rigid body dynamics model and the elastic dynamics model,the kinematic parameters of the robot are optimized with the driving torque of the driving arm as the evaluation index.Then,the inertia parameters were optimized by considering the three factors of the minimum low-order natural frequency,the overall mass of the system,and the driving torque of the auxiliary driving arm.The workspace of the robot was calculated according to the optimized kinematics parameters,and finally,its virtual prototype was designed.