scholarly journals Nonlinear Dynamic Characteristics Analysis of Shift Manipulator for Robot Driver with Multiple Joint Clearance

2021 ◽  
Author(s):  
Gang Chen ◽  
Xinyao Xu
Keyword(s):  
Dynamic Characteristic ◽  
Contact Force ◽  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Force Model ◽  
Characteristic Model ◽  
Clearance Joints ◽  
Clearance Joint ◽  
Nonlinear Dynamic Characteristics ◽  
Nonlinear Dynamic Characteristic

Abstract The clearance joint is very important to the nonlinear dynamic characteristics of mechanism. This paper presents a nonlinear dynamic characteristic model of shift manipulator for robot driver based on multiple revolute clearance joints to improve dynamic characteristics. The relative penetration depth and velocity between pin and bushing are obtained by establishing the kinematic model of the shift manipulator with clearance joint. Based on the improved L-N contact force model and the modified Coulomb friction model, the normal contact force and the tangential contact force of clearance joint are analyzed. With full clearance joints, the nonlinear dynamic characteristic model of the shift manipulator for robot driver is established. The nonlinear dynamic characteristic laws of the shift manipulator including the end displacement, velocity, acceleration and active joint driving torque are analyzed by different sizes of clearance joints. And the performance test of the shift manipulator for robot driver is conducted. The results demonstrate that the nonlinear dynamic characteristics are well analyzed and verified through the presented characteristic model with clearance joints.

Construction of a nonlinear dynamic characteristic model of pneumatic artificial rubber muscle manipulator using the magnetorheological (MR) brake

2012 ◽  
Vol 23 (9) ◽  
pp. 1011-1018 ◽  
Author(s):  
Hiroki Tomori ◽  
Yuichiro Midorikawa ◽  
Taro Nakamura
Keyword(s):  
Dynamic Characteristic ◽  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Magnetorheological Fluid ◽  
Early Response ◽  
Air Pressure ◽  
Late Response ◽  
Control Performance ◽  
Characteristic Model ◽  
Nonlinear Dynamic Characteristic

An artificial rubber muscle as an actuator was paid attention in this study because the manipulator was found to be safe to human when it comes in contact with human. However, this actuator vibrates easily with a late response because of the applied air pressure. Then, the magnetorheological brake that uses the magnetorheological fluid with an early response is built into the joint and controls the vibration. In this article, we have grasped the dynamic characteristics of a manipulator by the construction of a model for improvement in the control performance of the magnetorheological brake. Furthermore, the simulation was performed using the model, and efficient braking of the magnetorheological brake was examined.

scholarly journals Dynamics of Multibody Systems With Spherical Clearance Joints

2005 ◽  
Author(s):  
P. Flores ◽  
J. Ambro´sio ◽  
J. C. P. Claro ◽  
H. M. Lankarani
Keyword(s):  
Contact Force ◽  
Multibody Systems ◽  
Contact Forces ◽  
Force Model ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Clearance Joint ◽  
Contact Force Model ◽  
Dynamics Of Multibody Systems ◽  
The Impact

This work deals with a methodology to assess the influence of the spherical clearance joints in spatial multibody systems. The methodology is based on the Cartesian coordinates, being the dynamics of the joint elements modeled as impacting bodies and controlled by contact forces. The impacts and contacts are described by a continuous contact force model that accounts for geometric and mechanical characteristics of the contacting surfaces. The contact force is evaluated as function of the elastic pseudo-penetration between the impacting bodies, coupled with a nonlinear viscous-elastic factor representing the energy dissipation during the impact process. A spatial four bar mechanism is used as an illustrative example and some numerical results are presented, being the efficiency of the developed methodology discussed in the process of their presentation. The results obtained show that the inclusion of clearance joints in the modelization of spatial multibody systems significantly influences the prediction of components’ position and drastically increases the peaks in acceleration and reaction moments at the joints. Moreover, the system’s response clearly tends to be nonperiodic when a clearance joint is included in the simulation.

Reliability optimization design of a planar multi-body system with two clearance joints based on reliability sensitivity analysis

2018 ◽  
Vol 233 (4) ◽  
pp. 1369-1382 ◽  
Author(s):  
Yong Gao ◽  
Fang Zhang ◽  
Yuanyuan Li
Keyword(s):  
Sensitivity Analysis ◽  
Contact Force ◽  
Optimization Design ◽  
Great Influence ◽  
Force Model ◽  
Reliability Optimization ◽  
Clearance Joints ◽  
Clearance Joint ◽  
Reliability Sensitivity ◽  
Reliability Sensitivity Analysis

A general method for reliability sensitivity analysis and reliability optimization design of planar slider crank mechanism with two clearance joints was presented. A continuous contact force model considering energy dissipation was employed to estimate the contact force acting on the clearance joint. The Monte Carlo method was used to analyze the reliability sensitivity. In addition, based on the Kriging method, a surrogate model was constructed with consideration of explicit function expression. The precision and reliability of the presented method have been successfully demonstrated by numerical simulation. The results show that the number and position of clearance joint considered have a great influence on the maximum allowable displacement of the slider. The changing of the reliability sensitivity for the mean and variance of several random variables has certain regularity. Compared with the determinacy optimization design, the reliability optimization design presented here shows better dynamical performances.

Wave Motion Dynamic Analysis of Planar Frame Structures With Clearance Joints

2020 ◽  
Vol 16 (2) ◽  
Author(s):  
Juntao Zhu ◽  
Tuanjie Li ◽  
Zuowei Wang ◽  
Hangjia Dong
Keyword(s):  
Numerical Method ◽  
Dynamic Model ◽  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Wave Motion ◽  
Continuous Wave ◽  
Fdtd Method ◽  
Frame Structures ◽  
Clearance Joints ◽  
Nonlinear Dynamic Characteristics

Abstract Due to kinematic function requirements, deployable structures inevitably have many clearance joints. The existence of clearance joints not only reduces the structural stiffness but also leads to complex nonlinear dynamic characteristics. This paper proposed a general numerical method based on the wave motion theory, which is able to analyze these complex nonlinear dynamic characteristics of frame structures with clearance joints. The dynamic model of frame structures with clearance joints is derived on the basis of continuous wave equations. The clearance joint is modeling by combining Lankarani and Nikravesh contact model with the Ambrósio friction model. The established dynamic model of frame structures is solved by the finite difference time domain (FDTD) method. A triangular frame structure with two clearance joints is taken as the numerical example for the verification of the proposed numerical method. Numerical results show that the longitudinal wave affects the distribution direction of contact positions and the transverse wave mainly affects the distribution range of contact positions. It has been also found that the introduction of torsional springs with reasonable pretension torque is able to significantly improve the distribution of contact positions and reduce state uncertainties of clearance joints in structural vibrations.

Dynamic characteristics of planar linear array deployable structure based on scissor-like element with differently located revolute clearance joints

2017 ◽  
Vol 232 (10) ◽  
pp. 1759-1777 ◽  
Author(s):  
Bo Li ◽  
San-Min Wang ◽  
Viliam Makis ◽  
Xiang-Zhen Xue
Keyword(s):  
Mechanical System ◽  
Dynamic Characteristics ◽  
Equations Of Motion ◽  
Nonlinear Behavior ◽  
Friction Model ◽  
Dynamic Responses ◽  
Force Model ◽  
Clearance Joints ◽  
Deployable Structure ◽  
Clearance Joint

This paper comprehensively investigates the parametric effects of differently located revolute clearance joints on the dynamic behavior of planar deployable structure based on scissor-like element. Considering the real physical mechanical joints, the normal and the tangential forces in the revolute clearance joints are respectively modeled using Flores contact-force model and LuGre friction model. The resulting forces and moments are embedded in the equations of motion of the scissor deployable structure for accurately describing the effect of joint clearance and governing the dynamic response of this structure. The effects of the main parameters such as the location of the clearance joint, the clearance size and the number of clearance joints on the dynamic characteristics of a multibody mechanical system have been numerically evaluated, and the results indicate that joints at different locations in a mechanical system have different sensitivities to the clearance size, and the more sensitive joint should be controlled to reduce the nonlinear behavior of this structure. Also, it can be concluded that the motion in one revolute clearance joint will affect the motion in the other clearance joints and the dynamic interaction of clearance joints is the important source of structural behavior change. Therefore, in order to accurately predict the dynamic responses of the mechanical system, the clearance effect of each joint on the multibody system should be investigated and understood.

Nonlinear dynamic characteristics and control of planar linear array deployable structures consisting of scissor-like elements with revolute clearance joint

2020 ◽  
pp. 136943322097172
Author(s):  
Bo Li ◽  
San-Min Wang ◽  
Charis J Gantes ◽  
U-Xuan Tan
Keyword(s):  
Friction Coefficient ◽  
Contact Force ◽  
Initial Conditions ◽  
Equations Of Motion ◽  
Force Model ◽  
Deployable Structures ◽  
Clearance Joints ◽  
Continuous Contact ◽  
Clearance Joint ◽  
Parametric Effects

This paper comprehensively deals with the parametric effects of the joint clearance and friction coefficient on the dynamics of planar deployable structures consisting of scissor-like elements (SLEs). The dynamic model for scissor deployable structure is based on a comprehensive consideration of the symmetry and array characteristics of this mechanism and on a Lagrange method, which represents the motion equations. A modified nonlinear contact-force model is employed to evaluate the intrajoint contact force, and the incorporation of the friction effect between the inter-connecting bodies is included in this study. The total impact forces produced in the real mechanical joint are embedded into the dynamics and the differential equations of motion are solved numerically based on a set of initial conditions. The clearance size, angle velocity, and friction coefficient are analyzed and discussed separately. Using Poincaré map, the regular and irregular responses of the deployable mulitibody systems are observed. Next, a control scheme is evaluated to maintain a more stable behavior and continuous contact between the clearance joints. The controlled results are compared with those without control, concluding that some undesired effects caused by the clearance joints can be prevented or reduced, resulting in continuous contact at the clearance joint.

scholarly journals A Study on Clearance Effects on Dynamic Responses of Robot Manipulator

Mechanika ◽  
2021 ◽  
Vol 27 (2) ◽  
pp. 130-138
Author(s):  
Zhengfeng Bai ◽  
Tianxi LIU
Keyword(s):  
Contact Force ◽  
Robot Manipulator ◽  
Dynamic Responses ◽  
Joint Clearance ◽  
Force Model ◽  
Clearance Joints ◽  
Clearance Joint ◽  
Dynamic Performances ◽  
Simulation Results ◽  
The Impact

Clearances caused by assemblage, manufacturing errors and wear, affect inevitably the dynamic responses of mechanisms such as robot manipulator. In this study, the effects of clearance on a robot manipulator system are investigated numerically. The contact behavior along normal and tangential direction of clearance joint is described by a nonlinear contact force model and a modified Coulomb friction model respectively. Then, the dynamics equations of the robot manipulator system are established considering joint clearance. In order to investigate the effects of clearance on dynamic performances of practical mechanism, a planar robot manipulator system on a spacecraft system with a revolute clearance joint is used as the apply example. Four case studies for various clearance sizes are implemented to investigate and discuss the effects of joint clearance. The simulation results indicate that clearance joints have severe effects on the dynamic performances of mechanism system and the impact in clearance joints represented by contact force models must be considered in dynamics analysis and design of mechanism system. The simulation results in this work can predict the effects of clearance on robot manipulator system preferably and it is the basis of precision analysis, robust control system design of robot manipulator system.

Modeling and prediction of wear at revolute clearance joints in flexible multibody systems

2013 ◽  
Vol 228 (2) ◽  
pp. 317-329 ◽  
Author(s):  
Bo Zhao ◽  
Zhi-Nan Zhang ◽  
Xu-Dong Dai
Keyword(s):  
Contact Force ◽  
Multibody Systems ◽  
Flexible Multibody Systems ◽  
Force Model ◽  
Wear Prediction ◽  
Clearance Joints ◽  
Modeling And Prediction ◽  
Clearance Joint ◽  
Flexible Multibody ◽  
Flexible Component

This article proposes a numerical approach for the modeling and prediction of wear at revolute clearance joints in flexible multibody systems by integrating the procedures of wear prediction with multibody dynamics. In the approach, the flexible component is modeled based on the absolute nodal coordinate formulation. The contact force in the clearance joint is applied using the continuous contact force model proposed by Lankanrani and Nikravesh and the friction effect is considered using the LuGre friction model. The simulation of wear is performed by an iterative wear prediction procedure based on Archard’s wear model. The radial basis function neural network technique is employed to deal with the pin-on-disc experimental data for obtaining the wear coefficient used in the wear prediction procedure at different contact conditions. The comparison of the wear predicted at the clearance joint in the rigid and flexible planar slider-crank mechanisms demonstrates that the proposed approach can be used to model and predict wear at revolute clearance joints in flexible multibody systems, and the wear result predicted is slightly reduced after taking the flexibility of components into account.

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