Effects of Spherical Clearance Joint on Dynamics of Redundant Driving Spatial Parallel Mechanism

Robotica ◽  
2020 ◽  
pp. 1-17
Author(s):  
Xiulong Chen ◽  
Jingyao Guo
Keyword(s):  
Dynamic Characteristics ◽  
Parallel Mechanism ◽  
Dynamic Responses ◽  
Joint Clearance ◽  
Parallel Mechanisms ◽  
Spherical Joint ◽  
Ideal Situation ◽  
Spatial Parallel Mechanism ◽  
Redundant Drive ◽  
The Ideal

SUMMARY This paper proposes a dynamic modeling method of redundant drive spatial parallel mechanism, dynamics of 4-UPS-RPU redundant driving spatial parallel mechanism considering spherical joint clearance are analyzed. The dynamic equation of spherical joint clearance with Lagrange multiplier is built. The influences of single clearance and multiple clearances on dynamic responses of redundant drive spatial parallel mechanisms are analyzed under different clearance values. The results show that the dynamic characteristics of the mechanism with single clearance are basically consistent with the ideal situation, and the dynamic characteristics of the mechanism with multi-clearance are significantly different from the ideal situation.

scholarly journals Dynamics Behavior Analysis of Parallel Mechanism with Joint Clearance and Flexible Links

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Chen Xiulong ◽  
Jia Yonghao ◽  
Deng Yu ◽  
Wang Qing
Keyword(s):  
Parallel Mechanism ◽  
Dynamic Responses ◽  
Joint Clearance ◽  
Parallel Mechanisms ◽  
Nonlinear Dynamic Model ◽  
Lagrange Method ◽  
Flexible Links ◽  
Spatial Parallel Mechanism ◽  
Collision Force ◽  
Motion Characteristics

In this study, the dynamics behaviors analysis of parallel mechanism considering joint clearance and flexible links are investigated using a computational methodology. The nonlinear dynamic model of 4-UPS-RPS spatial parallel mechanism with clearance in spherical joint and flexible links is established by combining KED method and Lagrange method. The dynamic responses including collision force and motion characteristics of the moving platform are obtained. Chaos and bifurcation are analyzed. The effects of different clearances on the dynamics behaviors of the parallel mechanism are studied. The results show that 4-UPS-RPS spatial parallel mechanism is very sensitive to joint clearance and flexible links, and small variations in the clearance value can cause the mechanism change from periodic motion to chaotic motion. This research provides a methodology for forecasting the dynamics behavior of parallel mechanisms with clearance and flexible links.

Dynamic Response and Nonlinear Characteristics of Spatial Parallel Mechanism With Spherical Clearance Joint

2019 ◽  
Vol 14 (4) ◽  
Author(s):  
Chen Xiulong ◽  
Li Yuewen ◽  
Jia Yonghao
Keyword(s):  
Dynamic Response ◽  
Contact Force ◽  
Dynamic Equation ◽  
Parallel Mechanism ◽  
Joint Clearance ◽  
Spherical Joint ◽  
Nonlinear Characteristics ◽  
Clearance Joint ◽  
Spatial Parallel Mechanism ◽  
Moving Platform

Spherical joint is a type of common kinematic pair in spatial parallel mechanism. The existence of spherical joint clearance has many adverse effects on the mechanism. A method of forecasting the dynamic behaviors of spatial parallel mechanism with spherical clearance joint is proposed. The 4-UPS-UPU spatial parallel mechanism with spherical clearance is taken as the research object, the dynamic response, and nonlinear characteristics of the mechanism are studied. The kinematic model and the contact force model of the spherical clearance are established. The dynamic equation of the spatial parallel mechanism with spherical joint clearance is derived by Newton–Euler method. The above-mentioned dynamic equation is solved by using the ODE113 function that is based on a variable order numerical differential algorithm in matlab. The dynamic responses of moving platform with different clearance values are analyzed. The contact force and the center trajectory of the sphere at the spherical joint are obtained. In addition, the phase trajectory, Poincare map, and bifurcation diagram are analyzed, and the nonlinear characteristics of the spherical clearance joint and the moving platform are obtained. By comparing the results, such as the acceleration of moving platform and the contact force, with virtual prototype simulation, the correctness of the dynamic equation of the spatial parallel mechanism with spherical clearance joint and the analysis results are verified. The researches show that the change of clearance value has a great influence on the motion state of spherical clearance joint, and chaos phenomena appears in the clearance joint with the increase in the clearance value. And the impact phenomenon appears between the spherical joint elements, which makes the mechanism generated vibration.

scholarly journals Dynamics Analysis of Spatial Parallel Mechanism with Irregular Spherical Joint Clearance

2019 ◽  
Vol 2019 ◽  
pp. 1-21
Author(s):  
Xiulong Chen ◽  
Yuewen Li
Keyword(s):  
Dynamic Response ◽  
Contact Force ◽  
Parallel Mechanism ◽  
Euler Method ◽  
Joint Clearance ◽  
Force Model ◽  
Wear Depth ◽  
Spherical Joint ◽  
Spatial Parallel Mechanism ◽  
Dynamic Wear

Clearances caused by machining accuracy and assembly requirements are regular, but they will be irregular due to the wear of the kinematic pairs. At present, there are few studies on wear of space kinematic pairs. In order to grasp the effect of irregular spherical joint clearance after wear on the dynamic response, a method for solving irregular clearance problems based on the Newton–Euler method is proposed, and the dynamic response of 4-UPS-UPU spatial parallel mechanism with irregular spherical joint clearance is investigated. The kinematic model and contact force model of the clearance of the spherical joint are derived. The dynamic model of the mechanism with spherical joint clearance is established by the Newton–Euler method. Based on the Archard model, the three-dimensional dynamic wear model for spherical joint with clearances is developed. The wear depth and wear position of the spherical joint are obtained by the numerical solution. The method of reconstructing the geometric morphology after wear is proposed based on the finite element thought. The solution of the irregular clearance problem is put forward, and the dynamic response of the mechanism after wear is also analyzed. The results show that the dynamic response curves of the mechanism fluctuate around the ideal curves whether before wear or after wear. Compared with the regular clearance before wear, the results of the irregular clearance after wear have a greater impact on acceleration and contact force, and the vibration of the acceleration and contact force curve become more intense than before. Moreover, the displacement, velocity, and acceleration curves of the irregular clearance show some hysteresis than that before wear. Therefore, it can be inferred that the irregular clearance has more adverse effects on the mechanism and aggravates the wear between the elements of the kinematic joint; in addition, the stability and the reliability of the mechanism can be reduced.

scholarly journals Dynamic response analysis for multi-degrees-of-freedom parallel mechanisms with various types of three-dimensional clearance joints

2021 ◽  
Vol 18 (3) ◽  
pp. 172988142110177
Author(s):  
Jia Yonghao ◽  
Chen Xiulong
Keyword(s):  
Dynamic Response ◽  
Multibody Systems ◽  
Parallel Mechanism ◽  
Three Dimensional ◽  
Response Analysis ◽  
Parallel Mechanisms ◽  
Dynamics Model ◽  
Clearance Joints ◽  
Clearance Joint ◽  
Spatial Parallel Mechanism

For spatial multibody systems, the dynamic equations of multibody systems with compound clearance joints have a high level of nonlinearity. The coupling between different types of clearance joints may lead to abundant dynamic behavior. At present, the dynamic response analysis of the spatial parallel mechanism considering the three-dimensional (3D) compound clearance joint has not been reported. This work proposes a modeling method to investigate the influence of the 3D compound clearance joint on the dynamics characteristics of the spatial parallel mechanism. For this purpose, 3D kinematic models of spherical clearance joint and revolute joint with radial and axial clearances are derived. Contact force is described as normal contact and tangential friction and later introduced into the nonlinear dynamics model, which is established by the Lagrange multiplier technique and Jacobian of constraint matrix. The influences of compound clearance joint and initial misalignment of bearing axes on the system are analyzed. Furthermore, validation of dynamics model is evaluated by ADAMS and Newton–Euler method. This work provides an essential theoretical basis for studying the influences of 3D clearance joints on dynamic responses and nonlinear behavior of parallel mechanisms.

Design and workspace analysis of a 3-degree-of-freedom parallel swivel head with large tilting capacity

2015 ◽  
Vol 231 (10) ◽  
pp. 1838-1849 ◽  
Author(s):  
Jiangzhen Guo ◽  
Dan Wang ◽  
Rui Fan ◽  
Wuyi Chen
Keyword(s):  
Machine Tool ◽  
Parallel Mechanism ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Spherical Joint ◽  
Hybrid Machine Tool ◽  
Tilting Angle ◽  
Workspace Analysis ◽  
Hybrid Machine ◽  
Orientation Workspace

Traditional parallel mechanisms are usually characterized by small tilting capability. To overcome this problem, a 3-degree-of-freedom parallel swivel head with large tilting capacity is proposed in this article. The proposed parallel swivel head, which is structurally developed from a conventional 3-PRS parallel mechanism, can achieve a large tilting capability by means of structural improvements. First, a modified spherical joint with a maximum tilting angle of ±120° is devised to diminish the physical restrictions on the orientation workspace. Second, a UPS typed leg is introduced for the sake of singularity elimination. The superiority of the proposed parallel swivel head is theoretically proved by investigations of singularity-free orientation workspace and then is experimentally validated using a prototype fabricated. The theoretical and experimental results illustrate that the proposed parallel swivel head has a large tilting capacity and thus can be used as swivel head for a hybrid machine tool which is designed to be capable of realizing both horizontal and vertical machining.

Design and Experimental Study of a 3-DOF Parallel Swivel Head

2013 ◽  
Vol 418 ◽  
pp. 132-140
Author(s):  
Dan Wang ◽  
Jiang Zhen Guo ◽  
Rui Fan ◽  
Wu Yi Chen
Keyword(s):  
Experimental Study ◽  
Machine Tool ◽  
Parallel Mechanism ◽  
Experimental Results ◽  
Parallel Mechanisms ◽  
Spherical Joint ◽  
Hybrid Machine Tool ◽  
Tilting Angle ◽  
Hybrid Machine ◽  
Orientation Workspace

Traditional parallel mechanisms (PMs) are usually characterized by small tilting capability. To overcome this problem, a 3-DOF parallel swivel head (PSH) with large tilting capacity is proposed in this paper. The proposed PSH, which is structurally developed from a conventional 3-PRS parallel mechanism (PM), can achieve a large tilting capability by means of structural improvements. Firstly, a modified spherical joint with a maximum tilting angle of ±120o is devised to diminish the physical restrictions on the orientation workspace. Secondly, a UPS typed leg is introduced for the sake of singularity elimination. The superiority of the proposed PSH is theoretically proved by investigations of singularity-free orientation workspace and then is experimentally validated using a prototype fabricated. The theoretical and experimental results illustrate that the proposed PSH has a large tilting capacity and thus can be used as swivel head for a hybrid machine tool which is designed to be capable of realizing both horizontal and vertical machining.

scholarly journals Dynamic modeling of spatial parallel mechanism with multi-spherical joint clearances

2019 ◽  
Vol 16 (5) ◽  
pp. 172988141987591 ◽  
Author(s):  
Xiulong Chen ◽  
Chenghao Sun
Keyword(s):  
Dynamic Model ◽  
Dynamic Modeling ◽  
Parallel Mechanism ◽  
High Speed ◽  
Force Model ◽  
Spherical Joint ◽  
Universal Joint ◽  
Prismatic Joint ◽  
Spatial Parallel Mechanism ◽  
Joint Clearances

The parallel mechanism has advantages of the high speed, high precision, strong carrying capacity, and high structural rigidity. Most of the previous studies concerning the dynamic modeling focused on planar mechanisms with revolute clearance joints or spatial mechanisms with one spherical joint clearance, while few studies focused on spatial parallel mechanisms with multi-spherical joint clearances. In this article, a general dynamic modeling method for spatial parallel mechanism with multi-spherical joint clearances based on Lagrange multiplier method is proposed. Taking 4universal joint-prismatic joint-spherical joint/universal joint-prismatic joint- universal joint (4UPS-UPU) spatial parallel mechanism as an example, the constraint equations of common kinematic pairs in spatial parallel mechanism, such as universal joint, spherical joint, and prismatic joint, are derived in detail. The dynamic model of the parallel mechanism with two spherical joint clearances combining the Flores contact force model and the LuGre friction model is established. The correctness of model has also been verified by comparing the analysis results of MATLAB with those of ADAMS. It can be seen that dynamic model of spatial parallel mechanism with multi-spherical joint clearances could be easily established by this method, which provides a theoretical reference to establish the dynamic model of other parallel mechanism with multi-clearance in the future.

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