Dependability of a Complex System Having Two Types of Components

Li²

2009

IIM

This paper presents reliability and availability analyses of a model representing a system having one robot and n-redundant safety units with common-cause failures. At least k safety units must function successfully for the robot system success. The robot and other failure rates and the partially failed system repair rates are assumed constant and the failed robot-safety system repair time is assumed arbitrarily distributed. Markov and supplementary variable methods were used to perform mathematical analysis of this model. Generalized expressions for state probabilities, system availabilities, reliability, mean time to failure, and variance of time to failure are developed. Plots of some resulting expressions are shown

“…Using the supplementary method [12][13], the system of Equations associated with Figure 2 can be expressed as follows:…”

Section: Discussionmentioning

confidence: 99%

Probabilistic Analysis of a Robot System with Redundant Safety Units and Common-Cause Failures

Li²

2009

IIM

“…By using the supplementary method, we write the following Equations for Figure 2 (Gaver, 1963; Grag, 1963): Equation 1 Equation 2 Equation 3 Equation 4 Equation 5 Equation 6 Equation 7 where Equation 8 Equation 9 The associated boundary conditions as follows: Equation 10…”

Section: Generalized Robot‐safety System Analysismentioning

confidence: 99%

Reliability and availability analysis of a robot‐safety system

Cheng

Journal of Quality in Maintenance Engineering

2011

PurposeThe purpose of this paper is to study reliability, availability, and mean time to failure of a repairable robot‐safety system composed of n robots, m safety units, and a perfect switch.Design/methodology/approachGeneralized expressions for system state probabilities, system availability, reliability, and mean time to failure are developed. Supplementary variable and Markov methods were used to develop these expressions.FindingsThis study clearly demonstrates that backup robots, safety units, and the repair process help to improve system availability.Practical implicationsThis study will help maintenance engineers and reliability practitioners to become aware of the combined effect of backup robots, safety units, and the repair process on the performance of the robot‐safety system. Consequently, they will make better maintenance related decisions in organizations that make use of robots.Originality/valueThis paper has studied the effects of having redundant robots, safety units, and the repair facilities on the performance of a robot‐safety system with perfect mechanism to turn on a safety unit. This is one of the first attempts to study the combined effects of all these factors on a robot‐safety system.

“…Generalized robot-safety system analysis By using the supplementary method (Gaver, 1963;Grag, 1963), we write the following equations for the Figure 2 diagram:…”

Section: Rrs(s)mentioning

confidence: 99%

“…By using the supplementary method (Gaver, 1963; Grag, 1963), we write the following equations for the Figure 2 diagram: Equation 1 Equation 2 Equation 3 Equation 4 Equation 5 Equation 6 where: Equation 7 Equation 8 Equation 9 Equation 10 Equation 11 The associated boundary conditions are as follows: Equation 12 Equation 13 At time t =0, P 0 (0)=1, and other initial state probabilities are equal to zero.…”

Section: Generalized Robot‐safety System Analysismentioning

confidence: 99%

Probabilistic analysis of a repairable robot‐safety system composed of (n−1) standby robots, a safety unit, and a switch

Journal of Quality in Maintenance Engineering

Cheng²

2008

Purpose -The purpose of this paper is to study reliability, availability, and mean time to failure of a repairable robot-safety system composed of (n 2 1) standby robots, a safety unit, and a switch. Design/methodology/approach -Generalized expressions for system state probabilities, system availability, reliability, and mean time to failure are developed when the failure rates of robot and safety unit are constant and the failed system repair times are arbitrarily distributed. Supplementary variable and Markov methods were used to develop these expressions. Findings -This study clearly demonstrates that standby robots and the repair process help to improve system availability. Practical implications -This study will help maintenance engineers and reliability practitioners to become aware of the combined effect of standby robots and the repair process on the performance of the robot-safety system. Consequently, they will make better maintenance related decisions in organizations such as automobile manufacturers that use robots quite frequently. Originality/value -This paper has studied the effects of having redundant robots and the repair facilities on the performance of a robot-safety system with perfect mechanism to turn on a standby robot. This is one of the first attempts to study the combined effects of all these factors on a robot-safety system.