Dynamic Modeling and Analysis of 5-PSS/UPU Parallel Mechanism with Elastically Active Branched Chains

Abstract

To study the characteristics of the 5-prismatic–spherical–spherical (PSS)/universal–prismatic–universal (UPU) parallel mechanism with elastically active branched chains, the dynamics modeling and solutions of the parallel mechanism were investigated. First, the active branched chains and screw sliders were considered as spatial beam elements and plane beam element models, respectively, and the dynamic equations of each element model were derived using the Lagrange method. Second, the equations of the 5-PSS/UPU parallel mechanism were obtained according to the kinematic coupling relationship between the active branched chains and moving platform. Finally, based on the parallel mechanism dynamic equations, the natural frequency distribution of the 5-PSS/UPU parallel mechanism in the working space and elastic displacement of the moving platform were obtained. The results show that the natural frequency of the 5-PSS/UPU parallel mechanism under a given motion situation is greater than its operating frequency. The maximum position error is − 0.096 mm in direction Y, and the maximum orientation error is − 0.29° around the X-axis. The study provides important information for analyzing the dynamic performance, dynamic optimization design, and dynamic control of the 5-PSS/UPU parallel mechanism with elastically active branched chains.

Influence of atomizing core on droplet dynamic behavior and machining characteristics under synergistically enhanced twin-fluid spray

“…When the distance increases from 2.4 to 4.2 mm, for an average value in the range of axial distance from 200 to 600 mm, the RMS velocity fluctuation decreases from 1.92 m/s (for L = 2.4 mm), 1.84 m/s (for L = 3.0 mm), and 1.73 m/s (for L = 3.6 mm) to 1.65 m/s (for L = 4.2 mm). This indicates that the extension of the primary atomization period causes a decrease in injection power, which reduces the effect of aerodynamic force on the droplet RMS velocity fluctuation [40][41][42]. Furthermore, Fig.…”

Research on 4-UPUS Parallel Mechanism Ankle Joint Rehabilitation Training Robot

“…By comparing the kinematics analysis of the series mechanism, the performance evaluation of the Jacobian matrix of the speed relationship between the ankle joint and the motor was carried out on the two mechanisms [35]. Yu, Li Y, Lu B, Chen Z, and Cao Y respectively carried out kinematics analysis on the mechanism to solve the problems of total inverse, rotational inverse and forward kinematics [36][37][38][39][40].…”

Dynamic accuracy analysis of a 5PSS/UPU parallel mechanism based on rigid-flexible coupled modeling

“…The mapping relation between generalized system coordinates q and ˆi q can be written as: ˆi i  q R q (30) By assembling and superposing all the elastodynamic equations of the branch links as well as considering the effect of the system damping, the elastodynamic equations of the whole system of the 5-PSS/UPU parallel mechanism in the base coordinate system can be expressed as (31) where M is the total mass matrix of the system. C is the coefficient matrix considering the damping effect.…”

“…Therefore, the study of flexible deformation is very important to improve the dynamic accuracy of the mechanism. Taking a 5PSS/UPU coupling mechanism as an example [30,31], a closed vector chain method is proposed to reduce the influence of geometric errors on dynamic accuracy. Combing the finite element method with Lagrange method, the rigid-flexible coupling elastic dynamic equation of the system was established, and the effect of dynamic accuracy of component flexibility on the parallel mechanism was further analyzed.…”