Motion Performanc Analysis Of 6-PSS Parallel Mechanism

With the continuous development of industrial robot technology,parallel robots have attracted more and more scholars’ attention due to their high speed,high precision and good dynamic characteristics.They are widely used in high-speed grabbing,heavy-duty processing and high-precision poses.Adjustment of industrial sites such as institutions.However,with the increase of production demand,people have put forward higher performance requirements for parallel mechanisms,and parallel mechanisms still have problems such as small working space,complex analytical model,and difficulty in precision compensation.Therefore,it still has important research significance for the analysis of the motion performance of the mechanism.In order to study the motion performance of 6-PSS parallel mechanism,this paper carried out kinematics analysis,workspace solution,dynamics modeling and simulation,error modeling and analysis.It provides a theoretical basis for institutional task workspace planning and performance optimization.(1)According to the structural characteristics of the 6-PSS parallel mechanism,the fixed and dynamic coordinate systems and geometric models are established to solve the degree of freedom of the mechanism.The constrained vector method is used to solve the inverse solution of the mechanism.Based on the improved Newton iteration method,the kinematics positive solution of the mechanism is solved.According to the rigid body velocity projection theorem,the Jacobian matrix of the mechanism is obtained,and the inverse solution of the velocity and acceleration of the mechanism is solved.The singularity of the three mechanisms was analyzed by Gosselin’s singular analysis.The positional workspace and attitude workspace of the 6-PSS parallel mechanism are visually solved based on the subspace search method,which provides a basis for the organization trajectory planning and the performance distribution of the mechanism.The influence of the maximum corner constraint of the ball joint on the working space is quantitatively analyzed,and the reasonable selection of the ball joint is provided.(2)Parallel mechanism In order to ensure good dynamic performance under high speed and heavy load conditions,dynamic control model is often needed.Parallel mechanism dynamics modeling is the basis for dynamic analysis and control.In this paper,the rigid body inverse dynamics model of the mechanism is established by Lagrange method.The trajectory of the end of the ball under the conditions of the ball grabbing and the inner spherical milling are planned separately.The kinematics and dynamics simulation is performed under the Adams virtual prototype,and the results of the position,speed and driving force of the mechanism driving slider are solved.Compared with the analytical calculation results,the analytical results are consistent with the simulation results,which verifies the correctness of the mechanism kinematics and dynamics model.The maximum driving force of the branch under unit load is the force transmission coefficient.The distribution of force transmission performance in the workspace is analyzed,which provides a theoretical basis for task workspace selection and mechanism performance optimization under heavy load conditions.(3)Accuracy is an important performance of the parallel mechanism.In this paper,the geometric vector chain of the mechanism is established by the closed-loop vector method.The geometric error model of the mechanism is obtained by first-order perturbation of the vector chain.The mechanism geometric error model includes the driving error,the rod length error,the fixed platform installation error,the ball joint clearance error,and the parallelism error of the guide rail.The Monte Carlo method is used to solve the distribution of the parameter error at the end of the mechanism,and the error source pair mechanism is obtained.The effect of the end error.The standard deviation of the attitude error at the end of the mechanism is solved,and the distribution of the standard deviation of the end pose error in the workspace is analyzed.Based on the matrix singular value decomposition theory,the absolute sensitivity coefficient of the mechanism is defined,and the distribution of each component in the position work space and attitude work space is solved.The 2 norm of the error transfer matrix is defined as the error direction sensitivity coefficient,and the variation of the error sensitivity in all directions under different working conditions is analyzed.(4)Based on the Mac motion control card,the 6-PSS motion control software was programmed,and the gripping experiment and the inner spherical milling experiment were carried out to verify the correctness of the kinematics model.