Development and testing of a reliability performance index for modular robotic systems

Schneider, D.L.; Tesar, Delbert; Barnes, J.W.

doi:10.1109/rams.1994.291118

Cited by 14 publications

(10 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For each point on the algorithm first attempts to use a straight-line path. If this path is not obstacle free, then it attempts to find a monotonic quadratic path that is obstacle free up to a desired resolution of in (8). If no such path can be found then the algorithm discards this pair and uses the next pair that satisfies the necessary condition.…”

Section: Computing a Failure Surfacementioning

confidence: 99%

“…A number of studies have been dedicated to the assessment [6], [7] and analysis [5], [8]- [12] of robot safety and reliability, including robots designed primarily for this purpose [13]- [15]. The earliest work on kinematic failure tolerance [16] used the minimum singular value of the manipulator Jacobian matrix as a local worst-case measure of a robot's tolerance to a joint failure.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Failure-tolerant path planning for kinematically redundant manipulators anticipating locked-joint failures

2006

View full text Add to dashboard Cite

Abstract-This work considers kinematic failure tolerance when obstacles are present in the environment. It addresses the issue of finding a collision-free path such that a redundant robot can successfully move from a start to a goal position and/or orientation in the workspace despite any single locked-joint failure at any time. An algorithm is presented that searches for a simply-connected, obstacle-free surface with no internal local minimum or maximum in the configuration space that guarantees the existence of a solution. The method discussed is based on the following assumptions: a robot is redundant relative to its task, only a single locked-joint failure occurs at any given time, the robot is capable of detecting a joint failure and immediately locks the failed joint, and the environment is static and known. The technique is illustrated on a seven degree-of-freedom commercially available redundant robot. Although developed and illustrated for a single degree of redundancy, it is possible to extend the algorithm to higher degrees of redundancy.

show abstract

Section: Computing a Failure Surfacementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Failure-tolerant path planning for kinematically redundant manipulators anticipating locked-joint failures

2006

View full text Add to dashboard Cite

show abstract

“…For the case of a single degree of redundancy, this becomes or where the nonnegative scalar quantities ai represent some weighting [21].…”

Section: Defined Asmentioning

confidence: 99%

A local measure of fault tolerance for kinematically redundant manipulators

Roberts

Maciejewski

1996

IEEE Trans. Robot. Automat.

117

View full text Add to dashboard Cite

where i j denotes the j-th column of J, and (3) The reduced manipulator Jacobian i J then determines the kinematic properties of the degraded system. In this article, a local measure of fault tolerance is defined that measures the performance of the degraded system relative to the original system.In the next section, necessary and sufficient conditions are derived for determining whether a manipulator with a single degree of redundancy is in a configuration for which the reduced system is singular. Using this condition, one can then develop strategies that will avoid such configurations. Section III discusses how the manipulability of a manipulator is affected by a joint failure. Once this has been determined, configurations can be identified for which the manipulability is reduced by a minimum amount due to any joint failure. The case of multiple joint failures is considered in Section IV. Section V discusses the application of these results to motion planning and Section VI presents a fully general spatial example. Finally, conclusions appear in Section VII. II. FAULT INTOLERANT CONFIGURATIONSAs mentioned earlier, a joint failure can essentially result in a manipulator being in a singular configuration, even if the original Jacobian is of full rank. It is easy to show, using column space arguments, that the rank of the reduced Jacobian satisfies (1) Abstract-When a manipulator suffers a joint failure, its performance can be significantly affected. If the failed joint is locked, the resulting manipulator Jacobian is given by the original Jacobian, except that the column associated with the failed joint is removed. The rank of the resulting Jacobian then determines if the manipulator still has the ability to perform arbitrary end-effector motions. Unfortunately, even at an operating configuration that has a relatively high manipulability index, a joint failure may still result in a singular Jacobian. This work examines the problem of determining the reduced manipulability of a manipulator after one or more joint failures. Configurations that result in a minimal reduction of the manipulability index for any set of joint failures are determined.

show abstract

“…Example applications include space exploration [1,2], underwater exploration [3], and nuclear waste remediation [4,5] where there has been a great deal of research to improve manipulator reliability [6,7], design fault-tolerant robots [8,9], and determine mechanisms for analyzing [10], detecting [11,12], identifying [13][14][15], and recovering [16][17][18][19] from failures. Typical failure modes that have been considered include locked joint failures [20], where a joint is immobilized either due to the failure itself or due to the application of fail-safe brakes, and freeThis work was supported in part by the National Science Foundation under Contract IIS-0812437.…”

Section: Introductionmentioning

confidence: 99%

An Illustration of Generating Robots from Optimal Fault-Tolerant Jacobians

Ben-Gharbia¹,

Maciejewski²,

Roberts³

2010

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

View full text Add to dashboard Cite

The local kinematic properties of a robotic manipulator's configuration can be described by its corresponding Jacobian matrix. Conversely, one can determine a manipulator that possesses certain desirable kinematic properties by specifying the required Jacobian. In this work, design criteria that require a manipulator to function in a configuration that is optimal under normal operation and after an arbitrary single joint fails and is locked in position is first described. Specifically, the desired Jacobian matrix must be isotropic, i.e., possess all equal singular values prior to a failure, and have equal minimum singular values for every possible single column being removed. Then a simple planar three degree-of-freedom example is used to illustrate how one can identify all of the possible manipulator designs that possess the desired local properties described by the required structure of the Jacobian matrix. This paper concludes by showing that despite having identical local properties, the resulting manipulator designs have significantly different global kinematic properties that can be used to match a design to additional application-specific performance criteria.

show abstract

Development and testing of a reliability performance index for modular robotic systems

Cited by 14 publications

References 8 publications

Failure-tolerant path planning for kinematically redundant manipulators anticipating locked-joint failures

Failure-tolerant path planning for kinematically redundant manipulators anticipating locked-joint failures

A local measure of fault tolerance for kinematically redundant manipulators

An Illustration of Generating Robots from Optimal Fault-Tolerant Jacobians

Contact Info

Product

Resources

About