Task Compatibility of Manipulator Postures

Chiu, S.

doi:10.1177/027836498800700502

Cited by 271 publications

(115 citation statements)

References 8 publications

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“…Substituting (16) and (15) into (14) yields (17) Since Ui(O) and Vi(O) are available, the estimate of each 'a, (1) requires only 2m + 1 flops", Similar estimates can be derived for f u i(l) and f v i (I ), but we have found them to be quite poor. Therefore, we use (17) only to determine the worst-case joint failure index F; this requires using (17) to obtain estimates of all the singular values for all possible single locked-joint failures, and picking the failure that is the worst case.…”

Section: B Third Order Polynomial Approximationsupporting

confidence: 51%

“…Therefore, we use (17) only to determine the worst-case joint failure index F; this requires using (17) to obtain estimates of all the singular values for all possible single locked-joint failures, and picking the failure that is the worst case. Note that for every joint failure, estimates of all the singular values need to be computed, since the ordering of the singular values may change.…”

Section: B Third Order Polynomial Approximationmentioning

confidence: 99%

“…The SVD has long been a valuable tool for quantifying various dexterity measures: manipulability [15] (product of the singular values), isotropy [16] (ratio of the maximum singular value to the minimum), task compatibility [17] (weighted combination of singular values) and proximity to singularities [18] (minimum singular value). Each of these measures has its own physical interpretation.…”

Section: Introductionmentioning

confidence: 99%

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Real-time failure-tolerant control of kinematically redundant manipulators

Groom

Maciejewski

Balakrishnan

Proceedings of International Conference on Robotics and Automation

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The forward kinematics of manipulators are frequently represented as to potentially catastrophic incidents in remote and/or hazardous environments. A direct approach towards increasing robot reliability is to improve the reliability of the individual components; however, achieving acceptable reliability rates is often prohibitively expensive, and sometimes technologically impossible. An alternative approach is to consider failure-tolerant robot designs. These typically incorporate a failure detection and identification scheme [:3J followed by failure recovery [4J. Designing the robot with redundant systems increases the options available for failure tolerance. Redundancy can be in the form of duplication of actuators and sensors [5, 6J, or in the form of kinematic redundancy [7, 8, 9J. Proper utilization of kinematic redundancy provides greater dexterity prior to failures, minimizes the immediate impact of a failure, and guarantees task completion by ensuring a reachable postfailure workspace.This work presents real-time implementation of schemes for utilizing kinematic redundancy to maximize the tolerance of robots to single locked-joint failures. The fault-tolerance measure used is a worst-case quantity, given by the minimum, over all single joint failures, of the minimum singular value of the post-failure Jacobians. Maximizing this measure corresponds to configuring the robot to minimize the worst-case end-effector velocity error over all single locked-joint failures. This is also equivalent to minimizing the worst-case discontinuities in the joint velocities of the healthy joints as they move to compensate for the failed joint. The main contributions of this work are computationally efficient schemes for computing the fault-tolerance measure and its gradient, which in turn enable real-time optimal configuration of robots in anticipation of failures.where x is an m-dimensional vector representing the end-effector velocity, q is an n-dimensional vector describing the joint velocities, and J is the m by n manipulator Jacobian matrix [10]. For a redundant manipulator, n > m so the equation is underconstrained and there are an infinite number of solutions which can be expressed as ABSTRACT This work considers real-time fault-tolerant control of kinematically redundant manipulators to single locked-joint failures. The fault-tolerance measure used is a worst-case quantity, given by the minimum, over all single joint failures, of the minimum singular value of the post-failure Jacobians. Given any endeffector trajectory, the goal is to continuously follow this trajectory with the manipulator in configurations that maximize the fault-tolerance measure. The computation required to track these optimal configurations with brute-force methods is prohibitive for real-time implementation. We address this issue by presenting algorithms that quickly compute estimates of the worst-case fault-tolerance measure and its gradient. Real-time implementations are presented for all these techniques, and comparisons show that the perfo...

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Section: B Third Order Polynomial Approximationsupporting

confidence: 51%

Section: B Third Order Polynomial Approximationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Real-time failure-tolerant control of kinematically redundant manipulators

Groom

Maciejewski

Balakrishnan

Proceedings of International Conference on Robotics and Automation

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“…Chiu [34] proposed a task compatibility index to measure the level of agreement between the optimal directions of the manipulator and the actual moving directions required by the given task. The task compatibility index is considered for both force and velocity transmissions.…”

Section: Task Compatibilitymentioning

confidence: 99%

An overview of 3D object grasp synthesis algorithms

Sahbani

El-Khoury

Bidaud

2012

Robotics and Autonomous Systems

405

214

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a b s t r a c tThis overview presents computational algorithms for generating 3D object grasps with autonomous multi-fingered robotic hands. Robotic grasping has been an active research subject for decades, and a great deal of effort has been spent on grasp synthesis algorithms. Existing papers focus on reviewing the mechanics of grasping and the finger-object contact interactions Bicchi and Kumar (2000) [12] or robot hand design and their control Al-Gallaf et al. (1993) [70]. Robot grasp synthesis algorithms have been reviewed in Shimoga (1996) [71], but since then an important progress has been made toward applying learning techniques to the grasping problem. This overview focuses on analytical as well as empirical grasp synthesis approaches.

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“…in robotics) with other links through connecting joints are likely to result in complex resonances that shift in frequency and amplitude with manipulator posture [11], digital oscilloscope amplifier/ phase shifter Figure 3 Simple analog control active damping system using a piezoelectric ceramic sensor and actuator.…”

Section: Implementation Issuesmentioning

confidence: 99%

Embedded Sensors and Actuators for Lightweight Structures

Schoenwald

1990

Review of Progress in Quantitative Nondestructive Evaluation

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Task Compatibility of Manipulator Postures

Cited by 271 publications

References 8 publications

Real-time failure-tolerant control of kinematically redundant manipulators

Real-time failure-tolerant control of kinematically redundant manipulators

An overview of 3D object grasp synthesis algorithms

Embedded Sensors and Actuators for Lightweight Structures

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