Parallel Robots

doi:10.1007/1-4020-4133-0

Cited by 51 publications

(37 citation statements)

References 162 publications

(220 reference statements)

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“…A combination of universal and spherical joints for the base and the platform respectively, is the most common design of existing GSPs [41]. This combination is recognized as a 6-Universal-Prismatic-Spherical (6-UPS) architecture which has the minimum possible kinetic energy.…”

Section: Parametric Linearized Equations Of Motionmentioning

confidence: 99%

Influence of strut inertia on the vibrations in initially symmetric Gough–Stewart Platforms—an analytical study

Afzali-Far

Andersson

Nilsson

et al. 2015

Journal of Sound and Vibration

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Section: Parametric Linearized Equations Of Motionmentioning

confidence: 99%

Influence of strut inertia on the vibrations in initially symmetric Gough–Stewart Platforms—an analytical study

Afzali-Far

Andersson

Nilsson

et al. 2015

Journal of Sound and Vibration

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“…One possibility of finding the actual solution of the direct kinematics problem is to use iterative techniques such as Newton-Raphson procedures to solve the system of nonlinear kinematic constraint equations. These techniques require a good initial guess of the manipulator platform's pose on the one hand and a determinable pose that is sufficiently far away from a singular configuration on the other hand [28]. In this context, a singularity is a pose where the manipulator platform has at least one uncontrollable instantaneous degree of freedom leading to huge forces in the joints and the linear actuators, see, for example, References [29][30][31].…”

Section: Review Of Classical Solutions For the Direct Kinematics Problemmentioning

confidence: 99%

“…Different formulations and stop-criteria were proposed to obtain the actual pose (see, for example, Reference [28]) but every iterative method depends on the quality of the first pose estimation. In fact, the pose the algorithm converges to is neither necessarily the actual pose due to the quality of the initial pose estimation nor the closest possible pose next to the initial estimate [28]. The iterative algorithm might also fail to converge in case of singularities [28,51].…”

Section: Numerical Solutionmentioning

confidence: 99%

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Performance Evaluation of a Sensor Concept for Solving the Direct Kinematics Problem of General Planar 3-RPR Parallel Mechanisms by Using Solely the Linear Actuators’ Orientations

Schulz

2019

Robotics

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In this paper, we experimentally evaluate the performance of a sensor concept for solving the direct kinematics problem of a general planar 3-RPR parallel mechanism by using solely the linear actuators’ orientations. At first, we review classical methods for solving the direct kinematics problem of parallel mechanisms and discuss their disadvantages on the example of the general planar 3-RPR parallel mechanism, a planar parallel robot with two translational and one rotational degrees of freedom, where P denotes active prismatic joints and R denotes passive revolute joints. In order to avoid these disadvantages, we present a sensor concept together with an analytical formulation for solving the direct kinematics problem of a general planar 3-RPR parallel mechanism where the number of possible assembly modes can be significantly reduced when the linear actuators’ orientations are used instead of their lengths. By measuring the orientations of the linear actuators, provided, for example, by inertial measurement units, only two assembly modes exist. Finally, we investigate the accuracy of our direct kinematics solution under static as well as dynamic conditions by performing experiments on a specially designed prototype. We also investigate the solution formulation’s amplification of measurement noise on the calculated pose and show that the Cramér-Rao lower bound can be used to estimate the lower bound of the expected variances for a specific pose based exclusively on the variances of the linear actuators’ orientations.

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“…The parallel robot has excellent characteristics such as high speed, high precision, and high rigidity [1]. However, mechanical collisions between limbs and complexly existing singular configurations restrict its workspace.…”

Section: Introductionmentioning

confidence: 99%

How to Expand the Workspace of Parallel Robots

Harada¹

2017

Kinematics

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In this chapter, methods for expanding the workspace of parallel robots are introduced. Firstly, methods for expanding the translational workspace of the parallel robot are discussed. The parallel robot has multiple solutions of the inverse and forward displacement analysis. By changing its configurations from one solution to another, the parallel robot can expand its translational workspace. However, conventional nonredundant parallel robot encounters singularity during the mode change. Singularity-free mode changes of the parallel robot by redundant actuation are introduced. Next, methods for expanding the rotational workspace of the parallel robot are shown. In order to achieve the large rotation, some mechanical gimmicks by gears, pulleys, and helical joints have been embedded in the moving part. A novel differential screw-nut mechanism for expanding the rotational workspace of the parallel robot is introduced.

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Parallel Robots

Cited by 51 publications

References 162 publications

Influence of strut inertia on the vibrations in initially symmetric Gough–Stewart Platforms—an analytical study

Influence of strut inertia on the vibrations in initially symmetric Gough–Stewart Platforms—an analytical study

Performance Evaluation of a Sensor Concept for Solving the Direct Kinematics Problem of General Planar 3-RPR Parallel Mechanisms by Using Solely the Linear Actuators’ Orientations

How to Expand the Workspace of Parallel Robots

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