scholarly journals The Design of a Novel Prismatic Drive for a Three-DOF Parallel-Kinematics Machine

2005 ◽  
Vol 128 (4) ◽  
pp. 710-718 ◽  
Author(s):  
D. Chablat ◽  
J. Angeles
Keyword(s):  
Parallel Robot ◽  
Rolling Motion ◽  
Parallel Kinematics ◽  
Cam Mechanism ◽  
Pure Rolling ◽  
Parallel Kinematics Machines

The design of a novel prismatic drive is reported in this paper. This transmission is based on Slide-o-Cam, a cam mechanism with multiple rollers mounted on a common translating follower. The design of Slide-o-Cam was reported elsewhere. This drive thus provides pure-rolling motion, thereby reducing the friction of rack-and-pinions and linear drives. Such properties can be used to design new transmissions for parallel-kinematics machines. In this paper, this transmission is intended to replace the ball-screws in Orthoglide, a three-dof parallel robot intended for machining applications.

scholarly journals The Design of a Novel Prismatic Drive for a Three-DOF Parallel-Kinematics Machine

2004 ◽  
Author(s):  
J. Renotte ◽  
D. Chablat ◽  
J. Angeles
Keyword(s):  
Parallel Robot ◽  
Rolling Motion ◽  
Parallel Kinematics ◽  
Cam Mechanism ◽  
Pure Rolling ◽  
Parallel Kinematics Machines

The design of a novel prismatic drive is reported in this paper. This transmission is based on Slide-O-Cam, a cam mechanism with multiple rollers mounted on a common translating follower. The design of Slide-O-Cam was reported elsewhere. This drive thus provides pure-rolling motion, thereby reducing the friction of rack-and-pinions and linear drives. Such properties can be used to design new transmissions for parallel-kinematics machines. In this paper, this transmission is optimized to replace ball-screws in Orthoglide, a three-DOF parallel robot optimized for machining applications.

scholarly journals The Multiobjective Optimization of a Prismatic Drive

2007 ◽  
Author(s):  
E´milie Bouyer ◽  
Ste´phane Caro ◽  
Damien Chablat ◽  
Jorge Angeles
Keyword(s):  
Multiobjective Optimization ◽  
Contact Surface ◽  
Performance Index ◽  
Pareto Frontier ◽  
Rolling Motion ◽  
Objective Functions ◽  
Cam Mechanism ◽  
Pressure Angle ◽  
Pure Rolling

The multiobjective optimization of Slide-o-Cam is reported in this paper. Slide-o-Cam is a cam mechanism with multiple rollers mounted on a common translating follower. This transmission provides pure-rolling motion, thereby reducing the friction of rack-and-pinions and linear drives. A Pareto frontier is obtained by means of multiobjective optimization. This optimization is based on three objective functions: (i) the pressure angle, which is a suitable performance index for the transmission because it determines the amount of force transmitted to the load vs. that transmitted to the machine frame; (ii) the Hertz pressure used to evaluate the stresses produced on the contact surface between cam and roller; and (iii) the size of the mechanism, characterized by the number of cams and their width.

Static Balancing of a Parallel Kinematics Machine With Linear-Delta Architecture

2014 ◽  
Author(s):  
Alberto Martini ◽  
Marco Troncossi ◽  
Marco Carricato ◽  
Alessandro Rivola
Keyword(s):  
General Theory ◽  
Closed Loop ◽  
Parallel Robot ◽  
Design Solution ◽  
Robot Design ◽  
Gravity Compensation ◽  
Parallel Kinematics ◽  
Static Balancing ◽  
Milling Operation ◽  
Working Performance

The study deals with the compensation of gravity loads in closed-loop mechanisms as a possible strategy for enhancing their working performance. This work focuses on the Orthoglide 5-axis, a prototypal parallel robot for milling operation, characterized by linear-delta architecture with two further serial DOFs. Starting from a general theory formerly proposed by the authors, gravity compensation of the mechanism is analytically carried out. The statically balanced Orthoglide 5-axis can be obtained by installing on one leg a proper set of extension springs and a simple additional linkage. A feasible design solution for developing the device in practice is presented. The proposed balancing device can be implemented with minor modifications of the original robot design, thus appearing a profitable solution to be possibly extended to other machinery with similar architecture.

Nano-Meter Film Rheology and Asperity Lubrication

2002 ◽  
Vol 124 (3) ◽  
pp. 595-599 ◽  
Author(s):  
Bo Jacobson
Keyword(s):  
Contact Area ◽  
Pressure Fluctuations ◽  
Slip Rate ◽  
Hertzian Contact ◽  
Metal Contact ◽  
Rolling Motion ◽  
Oil Film ◽  
Pure Rolling ◽  
Total Separation ◽  
Molecular Dimensions

It is today possible to manufacture so smooth surfaces that they can elastically conform totally to each other over the whole Hertzian contact area. For pure rolling lubrication such surfaces only need an oil film of molecular dimensions to get total separation. When the rolling motion is combined with sliding, the pressure fluctuations inside the Hertzian contact redistribute the oil and make metal-to-metal contact possible. The redistribution velocity is a function of the slip rate S and the number of asperities N from the inlet to the outlet of the Hertzian contact area. The asperity top oil film thickness decreases with a factor of the order 2NS going from the inlet to the outlet of the Hertzian contact.

On the Terminology for Redundant Parallel Manipulators

2008 ◽  
Author(s):  
Andreas Mu¨ller
Keyword(s):  
Dynamic Properties ◽  
Parallel Manipulators ◽  
Point Of View ◽  
Linear Control Systems ◽  
Parallel Kinematics ◽  
Parallel Kinematics Machines ◽  
Geometric Point ◽  
Different Types ◽  
Potential Applications ◽  
General Mathematical Model

Different types of redundancy in parallel kinematics machines (PKM) can be used to improve their kinematic and dynamic properties. The meaning of redundancy of PKM is often differently understood in the literature. In this paper a terminology for redundant PKM is proposed. The basis for this classification is a general mathematical model. With the help of this model PKM are regarded as non-linear control systems. The different types of redundancy are clearly distinguished, and their potential applications are discussed. Redundancy is considered from a geometric point of view. Redundancy is a means to deal with singularities of PKM. The different types of singular configurations are considered in the paper, and the potential of redundancy to cope with such situations is discussed. Again singularities are considered from a geometric point of view.

Synthesis of the Pitch Cones of N-Lobed Elliptical Bevel Gears

2004 ◽  
Author(s):  
Giorgio Figliolini ◽  
Paolo Migliozzi
Keyword(s):  
Rolling Motion ◽  
Computer Animations ◽  
Bevel Gears ◽  
Matlab Program ◽  
Pure Rolling

A general formulation for the synthesis of the pitch cones of N-lobed elliptical bevel gears and the pitch surface of their conjugate crown-rack is proposed. In particular, both pitch cones and the pitch surface of their crown-rack can be obtained for any number and combination of lobes and in any configuration during their pure-rolling motion. This formulation has been implemented in a suitable Matlab program and several significant examples are shown, where circular bevel gears become a particular case. Computer animations are also available at URL: http://webuser.unicas.it/weblarm/larmindex.htm.

A Calibration Approach for the Parallel Kinematics Machines Tools Based on Error Sensitivity Analysis

2013 ◽  
Vol 842 ◽  
pp. 355-362
Author(s):  
Yong Shi ◽  
Wen Tao Liu
Keyword(s):  
Numerical Methods ◽  
Structural Parameters ◽  
Geometrical Parameters ◽  
Parallel Kinematics ◽  
Sensitivity Matrix ◽  
Error Sensitivity ◽  
Identification Method ◽  
Parallel Kinematics Machines ◽  
Error Sensitivity Analysis ◽  
Spatial Locations

In order to identify the geometrical parameters of parallel kinematics machines tools (PKM), a new parameters identification method is presented. The identification method is proposed based on a pose discrepancy model, which is deduced from the error between the nominal and measurement relative distance of two different spatial locations of the moving platform. In the identification method, an error sensitivity matrix, which expresses the sensitivity between the pose error and geometrical structural parameters error of PKM, can be created with numerical methods. The results of different numerical methods are analyzed. A measurement method to get the precise lengths of legs is presented, which decrease the number of identified parameters. In an experiment, the error of PKM is reduced from 6.71mm to 1.144mm. Therefore, the identification method is verified effective and feasible.

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