Modeling And Control Analysis Of Parallel Mechanism With Redundant Drive For Pipeline Attitude Adjustment

The six-degree-of-freedom parallel mechanism is one of the main attitude carriers for the docking of pipeline parts.The accuracy and stability of the docking mechanism is an important guarantee which the docking process can successfully complete.To this end,thesis develops a stiffness adjustable redundant drive parallel attitude docking platform based on the 6UPS/3SPS configuration,analyzes and studies the relevant performance indicators and control strategies of the mechanism,and completes the docking experiments of the pipeline,the specific research process is as follows:Firstly,thesis analyzes the Kinematics,dynamics and workspace of the redundantly driven parallel attitude adjustment platform.Based on the influence coefficient method,the mathematical model of the mapping relationship between the position,velocity and acceleration of the moving platform and each branch of the parallel mechanism are established.Thesis analyzes the driving forces of each branch with Newton’s Euler’s equation and virtual work principle in spinor form.A numerical example is given to verify the correctness of the mathematical model in ADAMS.Secondly,thesis analyzes the static stiffness of the redundant drive parallel attitude adjustment platform.Based on the displacement matrix method,the overall stiffness matrix of the mechanism is established,and the KSI and directional stiffness evaluation indexes are used to analyze the distribution pattern of the KSI values of the continuously changing mechanism of the redundant branches when the platform is in neutral position,and the trend of each directional stiffness of the redundant branches at three typical positions for a given motion law of the moving platform,respectively.Then,thesis analyzes the control simulation of the redundantly-driven parallelpositioning platform.This paper plans the attitude adjustment trajectory points of each driving branch with the B-spline curve and uses the particle swarm optimization algorithm to optimize the trajectory with the shortest time,The results show that the running time of each drive branch is further reduced without sudden changes in position,velocity and acceleration under the constraints of the electric cylinder motion;the position control simulation mathematical model of the drive branch is established,and the Simcape mechanical model is simulated using fuzzy PID control algorithm to provide technical support for the attitude docking experiment.Finally,thesis completes the prototype development and experimental analysis of the redundant drive parallel attitude adjustment platform.The mechanical structure,control system hardware and software interface of the attitude adjustment platform are selected and designed,and the motion simulation and attitude adjustment docking experiments are carried out according to the requirements of the attitude adjustment docking experiments to verify the effectiveness of the designed algorithm.