Theoretical, Experimental and Numerical Analyses for Painlevé Paradox of Two-Link Robotic Manipulator System

2019 ◽  
Author(s):  
Sai Zhang ◽  
Yunian Shen ◽  
Jiongcan Yang
Keyword(s):  
Change Process ◽  
Robotic Manipulator ◽  
Dynamic Responses ◽  
Gradual Change ◽  
Painlevé Paradox ◽  
Theoretical Derivation ◽  
Tangential Impact ◽  
Experiment And Simulation ◽  
Motion Characteristics ◽  
Set Up

Abstract When multi-rigid-body come into contact with a rough surface in certain configurations, multiple solutions or no solution would occur in the theoretical derivation of the dynamic equation, which is termed Painlevé paradox. In this paper, two-link robotic manipulator system as a kind of Painlevé paradox model is studied from theory, experiment and simulation. The theoretical solution is obtained by the linear complementary problem (LCP) method, which offers guidance to the experiment. Then the feasibility of experiment is validated by numerical simulation. For experiment, two-link robotic manipulator set-up is built. The apparatuses verify the continuity of two-link system motion as a function of initial configuration. The two-link robotic manipulator model is also built in LS-DYNA. The experiment and simulation results show that Painlevé paradox is always accompanied with dynamic jam. Meanwhile, there is no clear boundary between dynamic jam region and non-dynamic jam region derived as the LCP solution indicates. Instead, it tends to be a gradual change process with certain transformation law. Sticking-bounce motion is found in the experiment and simulation. Several different motion characteristics are concluded corresponding to the initial angles of the two links. The summary of the variation of dynamic responses is given for further studying the mechanism of tangential impact of similar robotic manipulator system, especially for guiding how to avoid such universal but unexpected action existing in robotic manipulator system.

scholarly journals Vibration characteristics of triple-gear-rotor system in compressed air energy storage under variable torque load

2021 ◽  
Vol 104 (1) ◽  
pp. 003685042098705
Author(s):  
Xinran Wang ◽  
Yangli Zhu ◽  
Wen Li ◽  
Dongxu Hu ◽  
Xuehui Zhang ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Element Model ◽  
Rotor System ◽  
Dynamic Responses ◽  
System Response ◽  
Rotating Speed ◽  
Torque Load ◽  
Set Up ◽  
Two Stages

This paper focuses on the effects of the off-design operation of CAES on the dynamic characteristics of the triple-gear-rotor system. A finite element model of the system is set up with unbalanced excitations, torque load excitations, and backlash which lead to variations of tooth contact status. An experiment is carried out to verify the accuracy of the mathematical model. The results show that when the system is subjected to large-scale torque load lifting at a high rotating speed, it has two stages of relatively strong periodicity when the torque load is light, and of chaotic when the torque load is heavy, with the transition between the two states being relatively quick and violent. The analysis of the three-dimensional acceleration spectrum and the meshing force shows that the variation in the meshing state and the fluctuation of the meshing force is the basic reasons for the variation in the system response with the torque load. In addition, the three rotors in the triple-gear-rotor system studied show a strong similarity in the meshing states and meshing force fluctuations, which result in the similarity in the dynamic responses of the three rotors.

LOWER LIMB REHABILITATION ROBOT FOR GAIT TRAINING

2014 ◽  
Vol 14 (06) ◽  
pp. 1440004 ◽  
Author(s):  
SHUAI GUO ◽  
JIANCHENG JI ◽  
GUANGWEI MA ◽  
TAO SONG ◽  
JING WANG
Keyword(s):  
Lower Limb ◽  
Degrees Of Freedom ◽  
Balance Training ◽  
Gait Training ◽  
Rehabilitation Robot ◽  
Stroke Patients ◽  
Motion Characteristics ◽  
Set Up ◽  
Limb Rehabilitation ◽  
Lower Limb Rehabilitation

After analyzing the rehabilitation needs of stroke patients and the previous studies on lower limb rehabilitation robot, our lower limb rehabilitation robot is designed for stroke patients' gait and balance training. The robot consists of the mobile chassis, the support column and the pelvis mechanism and it is described in detail. As the pelvis mechanism allows most of the patient's motion degrees of freedom (DOFs), the kinematics model of the mechanism is set up, and kinematics simulation is carried out to study the motion characteristics of the mechanism. After analyzing the calculation and simulation results, the pelvis mechanism is proven to measure up to the movement needs of the paralytic's waist and pelvis in walking rehabilitation process.

scholarly journals An Investigation of Dynamic Responses and Head Injuries of Standing Subway Passengers during Collisions

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Yong Peng ◽  
Tuo Xu ◽  
Lin Hou ◽  
Chaojie Fan ◽  
Wei Zhou
Keyword(s):  
Numerical Simulation ◽  
Head Injury ◽  
Head Injuries ◽  
Dynamic Responses ◽  
Passive Safety ◽  
Friction Coefficients ◽  
Safety Design ◽  
Parametric Studies ◽  
Simulation Results ◽  
Set Up

With the development of the subway and the pressing demand of environmentally friendly transportation, more and more people travel by subway. In recent decades, the issues about passenger passive safety on the train have received extensive attention. In this research, the head injury of a standing passenger in the subway is investigated. Three MADYMO models of the different standing passenger postures, defined as baseline scenarios, are numerically set up. HIC15values of passengers with different postures are gained by systematic parametric studies. The injury numerical simulation results of various scenarios with different friction coefficients, collision acceleration, standing angle, horizontal handrail height, and ring handrail height are analyzed. Results show that the horizontal handrail provides better protection in the three different standing passenger postures. Different friction coefficients and the standing angle have great impact on the head injuries of passengers in three different scenarios. The handrail height also has some effects on head injury of passengers with different standing postures, so it is necessary to be considered when designing the interior layout of the subway. This study may provide guidance for the safety design of the subway and some advices for standing subway passengers.

Generalized Kinematic Modeling of Reconfigurable Machine Tools

1998 ◽  
Vol 124 (1) ◽  
pp. 47-51 ◽  
Author(s):  
Yong-Mo Moon ◽  
Sridhar Kota
Keyword(s):  
Machine Tools ◽  
Screw Theory ◽  
Cost Effective ◽  
Mathematical Representation ◽  
Kinematic Modeling ◽  
Effective Manner ◽  
Systematic Selection ◽  
Motion Characteristics ◽  
Set Up ◽  
Representation Scheme

To accommodate frequent changes in product design and to be able to process a family of products in a timely and cost-effective manner, the next generation of machine tools should be reconfigurable. Reconfigurability enables reduction not only in machine design lead time but more significantly a reduction in machine set-up and ramp-up time. The essential characteristics of Reconfigurable Machine Tools (RMTs) include modularity, convertibility, flexibility, and cost-effectiveness. This paper presents a mathematical representation scheme using screw theory that lays the foundation for systematic design of reconfigurable machine tools. The motion characteristics of a set of desired machining tasks as well as stored library of machine modules are captured in a common representation scheme. A simple design example to illustrate the application of this methodology for systematic selection and synthesis of reconfigurable machine tools is presented.

scholarly journals Experimental Investigation of the Painlevé Paradox in a Robotic System

2008 ◽  
Vol 75 (4) ◽  
Author(s):  
Zhen Zhao ◽  
Caishan Liu ◽  
Wei Ma ◽  
Bin Chen
Keyword(s):  
Contact Point ◽  
Tangential Velocity ◽  
Rigid Bodies ◽  
Robotic System ◽  
Experimental Results ◽  
Painlevé Paradox ◽  
Dynamical Behaviors ◽  
Tangential Impact ◽  
System Of Rigid Bodies ◽  
Approach Zero

This paper aims at experimentally investigating the dynamical behaviors when a system of rigid bodies undergoes so-called paradoxical situations. An experimental setup corresponding to the analytical model presented in our prior work Liu et al. [2007, “The Bouncing Motion Appearing in a Robotic System With Unilateral Constraint,” Nonlinear Dyn., 49(1–2), 217–232] is developed, in which a two-link robotic system comes into contact with a moving rail. The experimental results show that a tangential impact exists at the contact point and takes a peculiar property that well coincides with the maximum dissipation principle stated in the work of Moreau [1988, “Unilateral Contact and Dry Friction in Finite Freedom Dynamics,” Nonsmooth Mechanics and Applications, Springer-Verlag, Vienna, pp. 1–82] the relative tangential velocity of the contact point must immediately approach zero once a Painlevé paradox occurs. After the tangential impact, a bouncing motion may be excited and is influenced by the speed of the moving rail. We adopt the tangential impact rule presented by Liu et al. to determine the postimpact velocities of the system, and use an event-driven algorithm to perform numerical simulations. The qualitative comparisons between the numerical and experimental results are carried out and show good agreements. This study not only presents an experimental support for the shock assumption related to the problem of the Painlevé paradox, but can also find its applications in better understanding the instability phenomena appearing in robotic systems.

The Identification of the Potential Limitations of Acoustic Rhinometery Using Computer-Generated, Three-Dimensional Reconstructions of Simple Models

1996 ◽  
Vol 10 (2) ◽  
pp. 77-82 ◽  
Author(s):  
A. Tomkinson ◽  
R. Eccles
Keyword(s):  
Nasal Cavity ◽  
Three Dimensional ◽  
Internal Surface ◽  
Three Dimensions ◽  
Gradual Change ◽  
Large Area ◽  
Cross Sectional ◽  
Wave Path ◽  
Acoustic Evaluation ◽  
Set Up

The internal surface of the nasal cavity is geometrically complicated and does not lend itself readily to direct measurement. Simple geometric shapes were used as a model for changes in the nasal cavity. Following the introduction of specific changes to a particular system, the effect of these changes on the acoustic evaluation of the space was studied. Cylinders were chosen, as the wave path could be assumed to be perpendicular to the model surface. The acoustic rhinometer's accuracy was assessed in the presence of small and large variations in cross sectional area, in the presence of a series of consecutive area changes, and a gradual change in diameter. The effect of the introduction of acoustic leak was also modelled. The acoustic data acquired from these models was used to reconstruct the model in three dimensions. These reconstructions were compared to the original model. The acoustic rhinometer was found to resolve with reasonable accuracy the dimensions of small spaces; however, if regions of sudden large area changes were present in the space, the data beyond these regions was highly unreliable. Furthermore, the presence of acoustic leak in a system had a similar effect. Unless precautions are taken in the set-up and operation of the acoustic rhinometer, the potential for misinterpretation of data and the introduction of bias is very high.

Dynamic Response Characteristics of Underground Powerhouse Caverns for Sandaowan Hydropower Station

2011 ◽  
Vol 382 ◽  
pp. 80-83 ◽  
Author(s):  
Zhen Zhong Shen ◽  
Hua Chun Ren
Keyword(s):  
Seismic Waves ◽  
Low Frequency ◽  
Time History ◽  
Element Model ◽  
Frequency Characteristics ◽  
Dynamic Responses ◽  
Principal Stresses ◽  
Underground Powerhouse ◽  
Response Characteristics ◽  
Set Up

According to the practical situation, the 3-D finite element model of Sandaowan underground powerhouse caverns on Taolai River is set up for analyzing the behaviors under earthquake action. Based on static stress field of the surrounding rock mass, and with the selection of appropriate seismic waves for dynamic time-history analysis method, the dynamic responses of underground powerhouse caverns are analyzed. It is shown that the time-history waveform of dynamic displacement of given points has a very similar variation regularity with that of acceleration, and the wave phases of both are almost synchronous. The dynamic displacements and principal stresses of the given points on rock walls are with the vibration of low-frequency characteristics, the acceleration response is with the vibration of high-frequency characteristics.

Rockfall Motion Trace of Road Slope Based on Damping and Rebounding Osculation Method

2011 ◽  
Vol 90-93 ◽  
pp. 3093-3096
Author(s):  
Zhong Yuan Yang
Keyword(s):  
Disaster Prevention ◽  
Mountain Slope ◽  
Rotational Angle ◽  
Side Slope ◽  
Hazard Risk ◽  
Design For Safety ◽  
Motion Characteristics ◽  
Set Up ◽  
Slope Design ◽  
Road Slope

Disaster degree and hazard risk of rockfall is essential for roadside slope design for safety. This paper is concerned with research efforts to calculate full motion trace of the rockfall along road slope with effective and numerical analysis methods. Two main terms including gradient of side slope and damping function between rockfall, mountain slope and rock speed are employed in so-called Damping and Rebounding Osculation Method (DROM). This tool is developed to define rock motion trace and delve into motion characteristics such as direction and rotational angle speed of the rockfall. Hereon, polygon rock is regarded as a rigid body of Non-particle and the motion formula are set up with the revolution motion of rock rigidity. The objective of this study is to accurately characterize the rockfall motion trace for disaster prevention and mitigation.

Dynamic Simulation and Analysis of Resistance Ring Correction Mechanism

2013 ◽  
Vol 365-366 ◽  
pp. 253-256
Author(s):  
Jie Qin ◽  
Ming Yu Zhang
Keyword(s):  
Motion Analysis ◽  
Dynamic Simulation ◽  
Virtual Prototype ◽  
Affecting Factors ◽  
Motion Characteristics ◽  
Set Up

A correction mechanism prototype is set up on the basis of ADAMS platform. Under the condition that the projectile is in the set flight state, the changing law and affecting factors of general kinetic motion characteristics of the correction mechanism virtual prototype are surveyed through motion analysis of resistance.

scholarly journals Analysis of the Effect of Number of Knots in a Trajectory on Motion Characteristics of a 3R Planar Manipulator

2012 ◽  
pp. 150-155
Author(s):  
Suparno C Bhattacharyya ◽  
Tarun Kanti Naskar
Keyword(s):  
Trajectory Planning ◽  
Robotic Manipulator ◽  
Trajectory Design ◽  
Linear Path ◽  
Order Polynomial ◽  
End Effectors ◽  
Motion Characteristics

The paper presents a method of trajectory planning and motion characteristics of a robotic manipulator. Main objective is to study the motion characteristics of a manipulator and to explore the scope of minimization of jerk. 8th order polynomial is considered for the trajectory design and the effect of number of intermediate knots between start and final positions of a 3R manipulator within the workspace is studied. Displacements, velocities, accelerations and jerk of end-effectors on a linear path are presented. The simulation for motion of the manipulator is done with the help of AutoLISP on AutoCAD platform.

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