ASSET HEALTH MONITORING
A machine management system, including one or more sensors arranged to take readings of one or more operating variables for a machine. Data processing equipment is arranged to receive data indicative of said operating variable readings for the machine and to analyse the received operational data to determine a probability distribution there-for. The processing equipment includes one or more modules of machine-readable code for assigning a value to one or more Stable distribution parameters in dependence on the received operational data, and a departure in the machine operation from a predetermined normal operating condition is determined from the assigned distribution parameter.
1 . A machine management system, comprising:
one or more sensors arranged to take readings of one or more operating variables for a machine;
data processing equipment arranged to receive data indicative of said operating variable readings for the machine and analyse the received operational data to determine a probability distribution there-for,
wherein the processing equipment comprises one or more modules of machine-readable code for assigning a value to one or more Stable distribution parameters in dependence on the received operational data, and a departure in the machine operation from a predetermined normal operating condition is determined from the assigned distribution parameter.
2 . A machine management system according to claim 1 , wherein the or each Stable distribution parameter is one of an index of stability, a skewness parameter, a scale parameter and a location parameter.
3 . A machine management system according to claim 1 , wherein a normal operating condition is defined using a Gaussian distribution and the departure in machine operation from the normal operating condition is based upon a difference between the assigned value of the Stable distribution parameter and a distribution parameter value according to said Gaussian distribution.
4 . A machine management system according to claim 1 , wherein the Stable distribution parameter defines a distribution having greater kurtosis than that of a Gaussian distribution.
5 . A machine management system according to claim 1 , wherein the Stable distribution parameter accommodates asymmetric behaviour in the data.
6 . A machine management system according to claim 1 , wherein a threshold parameter value is predetermined and an abnormality in machine operation is determined when said assigned distribution parameter meets or exceeds said threshold value.
7 . A machine management system according to claim 1 , wherein four Stable distribution parameters are assigned in dependence on the received operational data.
8 . A machine management system according to claim 1 , wherein the Stable distribution parameter is an index of stability, α and a departure in the machine operation from a predetermined normal operating condition is determined for the condition α<2.
9 . A machine management system according to claim 1 , wherein an initial value of the, or each, Stable distribution parameter is estimated using a quantile-based method.
10 . A machine management system according to claim 9 , wherein said initial value estimation is subsequently refined using a regression-based method.
11 . A machine management system according to claim 1 , comprising alerting means, wherein upon determination of a departure in the machine operation from a predetermined normal operating condition, the processing equipment outputs an alert signal via said alerting means.
12 . A machine management system according to claim 1 , comprising a scheduler for scheduling inspection, maintenance, or overhaul work in dependence on output of a signal from said processing equipment indicative of the determination of a departure from said normal operating condition.
13 . A method of determining an abnormality in the operation of a machine, comprising:
receiving data indicative of operating variable readings for the machine;
analysing the received operational data to determine a probability distribution there-for,
approximating the probability distribution by way of a Stable distribution by assigning a value to a plurality of Stable distribution parameters in dependence on the received operational data, and
determining a departure in the machine operation from a predetermined normal operating condition based upon the assigned distribution parameter value.
14 . A method according to claim 13 , wherein the determination of an abnormal operating condition comprises comparing the assigned distribution parameter value to a predetermined normal parameter value.
15 . A data carrier comprising machine-readable instructions for the control of one or more processors to perform the method of claim 13 .