Singular Simulation And Experimental Study Of Parallel Six Degrees Of Freedom Platform

In the weapons,aviation,and aerospace fields,there are often large-scale precision assembly and docking conditions.The docking accuracy is high,the weight of the docking section is large,and the range of motion is limited.The design and control of the six-degree-of-freedom platform of the load-bearing section are extremely difficult.Large,especially under the constraints of external vision,laser and other position measuring devices and space,it is often difficult to ensure that the six-degree-of-freedom platform is always in a non-singular workspace.For a type of deck with large bulges on the mating flange surface,the deck must be moved in a specified direction along the specified direction,and these long trajectories may approach or enter the singular region.This paper focuses on the singular expression of the six-degree-of-freedom platform in a fixed attitude,and discusses the long trajectory planning method with the singularity as the constraint.The simulation and experiment are carried out.The main contents are as follows:According to the structural characteristics of the typical section of the aviation field,the structure of the protruding butt flange surface is transformed into the constraint condition in the assembly process.The process method of the precision assembly of the large cabin is studied,and the assembly route is described by the analytical expression.The assembly process is transformed into the trajectory and attitude constraints of the attitude adjustment mechanism.Compared with the simple six-degree-of-freedom platform kinematics modeling,this paper combines the assembly cabin and the six-degree-of-freedom platform to establish a unified kinematic model,and study the relative attitude between the assembly cabin and the six-degree-of-freedom platform.The influence of the inverse solution transforms the relative motion between the segment to be assembled and the fixed segment into the multi-cylinder motion of the six-degree-of-freedom platform in the kinematics inverse solution algorithm,providing a method for the trajectory control of the six-degree-of-freedom platform.Compared with the singularity study of the simple six-degree-of-freedom platform,thepose singularity and the long trajectory motion on the assembly path are transformed into the singularity of the fixed pose.The singular analytic expression of the fixed pose of the six-degree-of-freedom platform is established.In this paper,the similarities and differences between the singular analytic expressions under different structural parameters are discussed,and the specific parameters of the singular analytic expression under the typical attitude parameters are obtained.In the Matlab environment,several typical singular simulations of the six-degree-of-freedom platform and the singular simulation of the fixed attitude are performed.The singular simulation results of the six-degree-of-freedom platform under the specified structural parameters are obtained,and a six-degree-of-freedom is established.The automatic assembly system of the platform is designed with the automatic assembly test of the typical cabin segment based on laser tracking.It avoids the singularity of the specified assembly path and is verified by the assembly test of the typical cabin.