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Stewart Platform (stewart + platform)

Distribution by Scientific Domains
Engineering100%

Selected Abstracts

A numerical method for the determination of dextrous workspaces of Gough,Stewart platforms

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 4 2001
L. J. du Plessis
Abstract An optimization approach to the computation of the boundaries of different dextrous workspaces of parallel manipulators is presented. A specific dextrous workspace is the region in space in which, at each position of the working point, a manipulator can control the orientation of its upper working platform through a specified range of orientation angles. Here the dextrous workspace is determined from the intersection of suitably chosen fixed orientation workspaces, which are found by application of a constrained optimization algorithm. The procedure is simple and has the considerable advantage that it may easily be automated. The method is illustrated by its application to both a planar and spatial Gough,Stewart platform. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Rider's net moment estimation using control force of motion system for bicycle simulator

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 11 2004
Jae-Cheol Shin
One of the challenging problems with bicycle simulators is to deal with the virtual bicycle dynamics that is coupled with rider's motion. For the virtual bicycle dynamics calculation and the real time simulation, it is necessary to identify the control inputs from the rider as well as the virtual environments. The steering, pedaling, and braking torques can be easily measured by using torque sensors and the virtual environments can be generated and provided by a visual system. However, direct measurement of the rider's net moment that significantly affects the bicycle motion is not practical. In this work, it is shown that six control forces of the Stewart platform-based motion system can be used for effective estimation of the rider's net moment, incorporated with the sliding mode controller with perturbation estimation. © 2004 Wiley Periodicals, Inc. [source]

Spherically actuated platform manipulator

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 3 2001
Robert L. Williams II
This article presents the inverse and forward pose and rate kinematics solutions for a novel 6-DOF platform manipulator, actuated by two base-mounted spherical actuators. The moving platform is connected to the fixed base by two identical spherical-prismatic-universal serial chain legs. The S -joint is active, and the remaining two joints in each chain are passive. An analytical solution is presented for the inverse pose problems, a semi-analytical solution is presented for the rate problems, and the numerical Newton,Raphson technique is employed to solve the forward pose problem. Unfortunately, the passive joint variables cannot be ignored in the kinematics solutions as they can for the Gough,Stewart platform. Examples are presented and hardware has been built, using two Rosheim Omni-Wrists on loan from NASA as the spherical actuators. © 2001 John Wiley & Sons, Inc. [source]

A numerical method for the determination of dextrous workspaces of Gough,Stewart platforms

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 4 2001
L. J. du Plessis
Abstract An optimization approach to the computation of the boundaries of different dextrous workspaces of parallel manipulators is presented. A specific dextrous workspace is the region in space in which, at each position of the working point, a manipulator can control the orientation of its upper working platform through a specified range of orientation angles. Here the dextrous workspace is determined from the intersection of suitably chosen fixed orientation workspaces, which are found by application of a constrained optimization algorithm. The procedure is simple and has the considerable advantage that it may easily be automated. The method is illustrated by its application to both a planar and spatial Gough,Stewart platform. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Kinematic optimal design of a paramill: A multi-SP device

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 6 2004
Jun-Ho Lee
In this paper, a manipulability analysis of a new parallel-type rolling mill, named "paramill," in its conceptual design stage is investigated. The paramill considered uses two Stewart platforms (SPs) in opposite directions for the generation of 6 degree-of-freedom motions of individual work-rolls. The objective of this new approach is to pursue an integrated control of the strip thickness, strip shape, pair-crossing angle, uniform wear of the rolls, and tension of the strip. The forward/inverse kinematics problems are formulated. Two main kinematic parameters, the size of the base and the acute angle made by two neighboring joints for a given size of the work-roll, have been determined in the way that the force and moment transmission from the actuators to the work-rolls is maximized. © 2004 Wiley Periodicals, Inc. [source]