Dynamics of a Two-DOF Parallel Pointing Mechanism

2005 ◽  
Author(s):  
Alessandro Cammarata ◽  
Rosario Sinatra
Keyword(s):  
Numerical Simulation ◽  
Parallel Mechanism ◽  
Inverse Dynamics ◽  
Kinematic Model ◽  
Degree Of Freedom ◽  
Numerical Examples ◽  
Proposed Model ◽  
Dynamic Analyses ◽  
Moving Platform ◽  
Two Degree Of Freedom

This paper presents kinematic and dynamic analyses of a two-degree-of-freedom pointing parallel mechanism. The mechanism consists of a moving platform, connected to a fixed platform by two legs of type PUS (prismatic-universal-spherical). At first a simplified kinematic model of the pointing mechanism is introduced. Based on this proposed model, the dynamics equations of the system using the Natural Orthogonal Complement method are developed. Numerical examples of the inverse dynamics results are presented by numerical simulation.

Kinematic, Stiffness, and Dynamic Analyses of a Compliant Tensegrity Mechanism

2014 ◽  
Vol 6 (4) ◽  
Author(s):  
Bahman Nouri Rahmat Abadi ◽  
S. M. Mehdi Shekarforoush ◽  
Mojtaba Mahzoon ◽  
Mehrdad Farid
Keyword(s):  
Dynamic Characteristics ◽  
Stiffness Matrix ◽  
Analytical Procedure ◽  
Inverse Dynamics ◽  
Virtual Work ◽  
Equations Of Motion ◽  
Degree Of Freedom ◽  
Principle Of Virtual Work ◽  
Numerical Examples ◽  
Dynamic Analyses

The objective of this study is to present an analytical procedure for analysis of a compliant tensegrity mechanism focusing on its stiffness and dynamic characteristics. The screw calculus is used to derive the static equations and stiffness matrix of a full degree-of-freedom tensegrity mechanism, and the equations of motion are derived based on the principle of virtual work. Finally, some numerical examples are solved for the inverse dynamics of the mechanism.

KINEMATICS AND WORKSPACE ANALYSIS OF A 3 DEGREE OF FREEDOM PARALLEL MECHANISM WITH PARALLELOGRAM LINKAGE

2017 ◽  
Vol 41 (5) ◽  
pp. 922-935
Author(s):  
HongJun San ◽  
JunSong Lei ◽  
JiuPeng Chen ◽  
ZhengMing Xiao ◽  
JunJie Zhao
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Method ◽  
Analytical Method ◽  
Theoretical Basis ◽  
Parallel Mechanism ◽  
Graphical Method ◽  
Degree Of Freedom ◽  
Workspace Analysis ◽  
Fixed Base ◽  
Moving Platform

In this paper, a 3-DOF translational parallel mechanism with parallelogram linkage was studied. According to the space vector relation between the moving platform and the fixed base, the direct and inverse position solutions of this mechanism was deduced through analytical method. In addition, the error of the algorithm was analyzed, and the algorithm had turned out to be effective and to have the satisfactory computational precision. On the above basis, the workspace of this mechanism was found through graphical method, which was compared with that of finding through Monte Carlo method, and there was the feasibility for analyzing the workspace of the mechanism by graphical method. The characteristic of the mechanism was analyzed by comparing the results of two analysis methods, which provided a theoretical basis for the application of the mechanism.

Reactionless Two-Degree-of-Freedom Planar Parallel Mechanism With Variable Payload

2009 ◽  
Author(s):  
Alexandre Lecours ◽  
Cle´ment Gosselin
Keyword(s):  
Dynamic Simulation ◽  
Parallel Mechanism ◽  
Reaction Force ◽  
Simulation Software ◽  
Degree Of Freedom ◽  
Dynamic Balancing ◽  
End Effector ◽  
Planar Mechanism ◽  
Two Degree Of Freedom ◽  
Arbitrary Trajectory

A reactionless mechanism is one which does not exert any reaction force or moment on its base at all times, for any arbitrary trajectory of the mechanism. This paper addresses the static and dynamic balancing of a two-degree-of-freedom parallel planar mechanism (five-bar mechanism). A simple and effective adaptive balancing method is presented that allows the mechanism to maintain the reactionless condition for a range of payloads. Important proofs concerning the balancing of five-bar mechanisms are also presented. The design of a real mechanism where parallelogram linkages are used to produce pure translations at the end-effector is also presented. Finally, using dynamic simulation software, it is shown that the mechanism is reactionless for arbitrarily chosen trajectories and for a variety of payloads.

A Two Degree of Freedom Nanopositioner With Electrothermal Actuator for Decoupled Motion

2011 ◽  
Author(s):  
Yong-Sik Kim ◽  
Nicholas G. Dagalakis ◽  
Satyandra K. Gupta
Keyword(s):  
Design Concept ◽  
Degree Of Freedom ◽  
Motion Platform ◽  
Element Analysis ◽  
Electrothermal Actuators ◽  
Electrothermal Actuator ◽  
Decoupled Motion ◽  
Moving Platform ◽  
Two Degree Of Freedom ◽  
Novel Design

Building a two degree-of-freedom (2 DOF) MEMS nanopositioner with decoupled X-Y motion has been a challenge in nanopositioner design. In this paper a novel design concept on making the decoupled motion of the MEMS nanopositioner is suggested. The suggested nanopositioner has two electrothermal actuators and employs a fully nested motion platform with suspended anchors. The suggested MEMS nanopositioner is capable of delivering displacement from the electrothermal actuator to the motion platform without coupled motion between the two X-Y axes. The design concept, finite element analysis (FEA) results, fabrication procedures and the performance of the 2 DOF nanopositioner is presented. In order to test the nanopositioner moving platform decoupled motion, one actuator moves the platform by 60 μm, while the other actuator is kept at the same position. The platform position cross talk error was measured to be less than 1 μm standard deviation.

A two-degree-of-freedom ambulance stretcher suspension, Part 2: Simulation of system performance with capillary and orifice pneumatic damping

1998 ◽  
Vol 212 (3) ◽  
pp. 227-240 ◽  
Author(s):  
R. J. Henderson ◽  
J. K. Raine
Keyword(s):  
Numerical Simulation ◽  
System Performance ◽  
Degree Of Freedom ◽  
Shaking Table ◽  
Potential Improvement ◽  
Two Degree Of Freedom ◽  
Isolation Performance ◽  
Suspension Performance

Part 1 of this paper gave an overview of the design and dynamics of a two-degree-of-freedom pneumatic stretcher suspension. Part 2 reviews pneumatic damping methods and then investigates system isolation performance using capillary and orifice damping restrictions. These restrictors are compared by numerical simulation of the suspension response when subjected to vertical transient inputs from the ambulance floor. Very good isolation of the stretcher patient is shown to be possible when a suitable damping restriction is used. Brief observations are also made regarding expected suspension performance in pitch and the potential improvement from introducing semi-active pneumatic damping. Part 3 will report results of suspension tests on a laboratory shaking table and in an ambulance.

scholarly journals Design of a Planar Cable-Driven Parallel Crane Without Parasitic Tilt

2021 ◽  
Author(s):  
Lionel Etienne ◽  
Philippe Cardou ◽  
Marceau Métillon ◽  
Stéphane Caro
Keyword(s):  
Total Mass ◽  
Parallel Robots ◽  
Degree Of Freedom ◽  
Mobile Platform ◽  
Moving Platform ◽  
High Dynamics ◽  
Two Degree Of Freedom ◽  
High Payload

Abstract Cable-Driven Parallel Robots (CDPRs) offer high payload capacities, large translational workspace and high dynamics performances. Their rotational workspace is generally far more limited, however, which can be resolved by using cable loops, as was shown in previous research. In the case of fully-constrained CDPRs, cable loops can induce unwanted torques on the moving-platform, causing it to tilt and move away from its intended position, which we call parasitic tilt. Hence, the orientation accuracy of such robots is usually limited. This paper deals with the design, modelling and prototyping of a planar CDPR with infinite rotations, without parasitic tilt and without an additional motor. This robot, which we call a Cable-Driven Parallel Crane (CDPC), is composed of a mobile platform (MP) with an embedded mechanism and a transmission module. The MP is linked with the frame by a parallelogram of three cables to constrain its orientation, including a cable loop, as well as a fourth cable. The two-degree-of-freedom (dof) motions of the moving-platform of the CDPC and the internal dof of its embedded mechanism are actuated by a total of three actuators, which are fixed to the frame. As a consequence, the overall system is fully-actuated, its total mass and inertia in motion is reduced and it is free of parasitic tilts.

Inverse Dynamics of 2UPS-2RPS Parallel Mechanism Based on Virtual Work Principle

2010 ◽  
Vol 29-32 ◽  
pp. 744-749 ◽  
Author(s):  
Wen Hua Wang ◽  
Zhi You Feng ◽  
Ting Li Yang ◽  
Ce Zhang
Keyword(s):  
Computer Simulation ◽  
Kinematic Analysis ◽  
Parallel Mechanism ◽  
Inverse Dynamics ◽  
Virtual Work ◽  
Dynamic Equations ◽  
Inverse Dynamic ◽  
Virtual Work Principle ◽  
Inverse Dynamic Model ◽  
Moving Platform

Inverse dynamic equations of the 2UPS-2RPS mechanism are formulated by utilizing the virtual work principle. Kinematic analysis of the mechanism is presented, on the basis of which the Jacobian matrices of the limbs and the mechanism are deduced. By combining the dynamics of the limbs and the moving-platform, the inverse dynamic model of the mechanism is obtained. Finally a computer simulation is carried out to demonstrate the dynamic analysis of the moving platform.

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