Failure Tolerance through Active Braking: A Kinematic Approach

English, James; Maciejewski, Anthony A.

doi:10.1177/02783640122067408

Cited by 31 publications

(8 citation statements)

References 20 publications

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“…That is, if one robot has a free swinging joint failure, described as in [23,24], we would like to ensure that when the functional robot joins at the socket, the resulting cooperative workspace is as large as possible. The geometry of the problem is illustrated at Figure 1.…”

Section: Formal Problem Statementmentioning

confidence: 99%

Illustration of Numerical Algebraic Methods for Workspace Estimation of Cooperating Robots after Joint Failure

Brake¹,

Bates²,

Putkaradze³

et al. 2010

IASTED Technology Conferences / 705: ARP / 706: RA / 707: NANA / 728: CompBIO

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We consider the estimation of the post-failure workspace of two two-link serial robots where the free-swinging failure of one robot's last joint is handled by having the functional robot grasp the final link of the broken robot. We present an algorithm for finding the optimal placement of such synergistic robot arms and the optimal grasp point on the final link of the broken robot. To determine whether a point in the pre-failure workspace of the broken robot remains in the post-failure workspace, we solve an inverse kinematics problem in the form of a polynomial system. Homotopy continuation provides an efficient means for solving such polynomial systems, so we use the software package Bertini. Finally, Monte-Carlo methods are used to estimate the post-failure workspace.

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Section: Formal Problem Statementmentioning

confidence: 99%

Illustration of Numerical Algebraic Methods for Workspace Estimation of Cooperating Robots after Joint Failure

Brake¹,

Bates²,

Putkaradze³

et al. 2010

IASTED Technology Conferences / 705: ARP / 706: RA / 707: NANA / 728: CompBIO

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“…There have been many studies on the faults of actuators. In those studies, methods to improve the tracking performance of manipulators have introduced, such as [5]- [9]. For examp le, in [5], the locked joint failure was addressed with matrix perturbation methodology which is extended to deal with mu ltiple locked joint failures.…”

Section: Introductionmentioning

confidence: 99%

Effect of Actuator Torque Degradation on Behavior of a 6-DOF Industrial Robot

Truc¹,

Nghia²,

Thành³

et al. 2020

ujme

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Actuator fau lts of robot man ipulators may occur during their lifet ime after long time in operation. There are several kinds of actuator failures such as locked joints, free-swinging joints, and loss of actuator torque effectiveness. The main goals of this paper are (i) to classify the loss of torque effectiveness, called torque degradation, into three divergent cases: Boundary Degradation of Torque (BDT), Boundary Degradation of Torque Rate (BDTR), and Proportional Degradation of Torque (PDT); and (ii) to analyze their effect on behavior of a typical industrial robot. The possible failures might degrade the whole system performance or in some certain cases leading to unavoidable damages. In normal operation, we do not have a controller designed specifically for these faults. In order to have a better understanding on how the mentioned problems affect robot operations, with an assumption that the knowledge of robot parameters are known, a closed-loop control law is used to demonstrate the control ability in dealing with these cases. By taking advantage of MATLAB/Simscape Multibody, the quasi-physical model of robot is employed instead of expensive prototypes and experiments. Simulat ion results show that the joint responses according to different types of failures. In many cases, the robot cannot track the reference trajectories properly.

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“…In Ref. [6], FSJFs for serial robots were handled by utilizing gravity to achieve partial control of the passive joint. It was shown that the fault-tolerant workspace could be increased by utilizing active braking to let the joint vary between locked and free swinging.…”

Section: Introductionmentioning

confidence: 99%

Novel Fault-Tolerance Indices for Redundantly Actuated Parallel Robots

Isaksson

Marlow

Maciejewski

et al. 2017

Journal of Mechanical Design

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Robots designed for space applications, deep sea applications, handling of hazardous material and surgery should ideally be able to handle as many potential faults as possible. This paper provides novel indices for fault tolerance analysis of redundantly actuated parallel robots. Such robots have the potential for higher accuracy, improved stiffness, and higher acceleration compared to similar-sized serial robots. The faults considered are free-swinging joint failures (FSJFs), defined as a software or hardware fault, preventing the administration of actuator torque on a joint. However, for a large range of robots, the proposed indices are applicable also to faults corresponding to the disappearance of a kinematic chain, for example, a breakage. Most existing fault tolerance indices provide a ratio between a robot's performance after the fault and the performance before the fault. In contrast, the indices proposed in this paper provide absolute measures of a robot's performance under the worst-case faults. The proposed indices are based on two recently introduced metrics for motion/force transmission analysis of parallel robots. Their main advantage is their applicability to parallel robots with arbitrary degrees-of–freedom (DOF), along with their intuitive geometric interpretation. The feasibility of the proposed indices is demonstrated through application on a redundantly actuated planar parallel mechanism.

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Failure Tolerance through Active Braking: A Kinematic Approach

Abstract: Abstract

Cited by 31 publications

References 20 publications

Illustration of Numerical Algebraic Methods for Workspace Estimation of Cooperating Robots after Joint Failure

Illustration of Numerical Algebraic Methods for Workspace Estimation of Cooperating Robots after Joint Failure

Effect of Actuator Torque Degradation on Behavior of a 6-DOF Industrial Robot

Novel Fault-Tolerance Indices for Redundantly Actuated Parallel Robots

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