CN103399994A - Optimization method of periodic inspection process and maintenance of airplanes based on uncertain network planning techniques - Google Patents

Abstract

The invention discloses an optimization method of periodic inspection process of airplanes based on uncertain network planning techniques, aims to optimize the periodic inspection process of the airplanes and reduce shutdown time thereof, and solves the problem of uncertainty in process time parameters during optimization of the period inspection process. The optimization method includes structuring uncertain network planning graphs for the periodic inspection process of the airplanes, determining uncertain network plans for the periodic inspection process of the airplanes, and optimizing certain network plans of the periodic inspection process of the airplanes, wherein the uncertain network planning graphs for the periodic optimization process of the airplanes are structured according to characteristics of periodic inspection; collected periodic inspection data are analyzed on the basis of field survey data information, normal time of each activity is determined by the aid of one estimate approach of qualified probability based on the genetic algorithm, and the problem of uncertain network planning optimization is converted into certain network planning optimization; the periodic inspection process is optimized by the aid of a PERT_CPM module of WinQSB software, and parameters such as critical paths and complete time of the periodic inspection process are determined. By the optimization method, requirements for high efficiency and engineering operability can be met.

Description

Aircraft regular inspection flow optimization method based on the probabilistic network scheduling technology

Technical field

The invention belongs to the aeronautical maintenance technical field, relate to the expected duration of determining operation based on the restriction probability triple-time estimate method of genetic algorithm, solve regular inspection flow process probabilistic network scheduling deterministic problem, determine the parameters such as the critical path of regular inspection flow process and completion date.

Background technology

After aircraft was made regular check on and safeguarded that (periodic inspection and maintenance is called for short regular inspection) be the flight (airborne hours) of asking during through one section at aircraft, aircraft, engine and airborne equipment were certain to because wearing and tearing become loosening and are corroded.The quality of the hydraulic pressure machine oil of aircraft system, lubricated wet goods can worsen and quantity can reduce, and need to again change or supplement, so aircraft is after flight after a while, the inspection that the maintenance personal will be correlated with and repairing.Do for each system of aircraft to check and test is in order to find and solve fault and deficiency, make the reliability of aircraft return to original level, could allow it complete the work of following flight time section.

The work of aircraft regular inspection relates generally to a plurality of professional collaborative works.In whole regular inspection process, existing information interaction in flow process between each professional regular inspection work, independent operation is also arranged, existing hardware operation, software operation is also arranged, and existing regular inspection flow process is the angle design from single specialty, rarely has the relevance of considering each professional operating process, the shortage science, rationally, the parallel work-flow rules of standard, it is unreasonable, not smooth that this just causes linking between each specialty to coordinate, and causes the prolongation of whole system time between predetermined repairs.

Existing aircraft regular inspection process optimization research focuses on that mainly maintainer's experience carries out, lack corresponding theory support, and applicability is not high, and the information that the maintainer provides is due to its knowledge, experience and bias, may there be deviation in data, are not easy to promote the use of; In flow process, the duration of each operation and Duration Variance computing formula fixed single, can not change with actual conditions; Ignored the impact of each professional collaborative work on time between predetermined repairs in regular inspection work, the operation expected duration of calculating has deviation.Carry out the process optimization of aircraft regular inspection and help to improve maintainer's collaborative work efficiency, shorten the regular inspection cycle, the reliability that improves aircraft all has great importance.

The method for solving of process optimization problem has multiple, and as mathematics planing method and heuristic, but there are the problems such as calculated amount is large, efficiency is not high in the former for extensive problem, and the latter is only for particular problem, and versatility is poor.In recent years, the research of process optimization problem mainly concentrates on the intelligent optimization algorithm aspect, as particle cluster algorithm, genetic algorithm, Artificial Immune Algorithm and ant group algorithm etc., can solve large space, the complicated optimizing problem such as non-linear, but easy Premature Convergence, make search be absorbed in locally optimal solution, or iteration speed is slow, calculated amount is large, the engineering operability is poor.

Network planning technique is a kind of plan management method of science, take the planning model of network chart as basis, comprises critical path method (CPM) and program evaluation and review technique (PERT).In the process of establishment Task Network plan, the duration of each operation can not accurately be determined in advance, can only according to different situations, make estimation roughly.Traditional disposal route has two kinds: the one, first provide 3 kinds of possible times of operation, i.e. and optimistic time, conservative time and most likely time, then weighted mean obtains the expected duration of operation, and the 2nd, directly provide the expected duration of operation.

Although classical PERT is extensively used till today always, this method has certain limitation.Its assumed condition and parameter value require too harsh, are difficult to reflect changeable, uncertain realistic problem; Its duration mean variance computing formula fixed single, can not change with actual conditions.In the last few years, the scholars such as Hahn, Jose queried the rationality of classical PERT formula of variance one after another, and had proposed improving one's methods separately.But, the calculating of they are more or less complicated average and variance.Hahn has introduced parameter Θ Beta is distributed and to mix the formation Mixture Distribution Model with being uniformly distributed, and by estimation Θ value, regulates the described probabilistic size of model, and then regulates variance; Jose has constructed one and has adjusted variable C(δ) adjust the size of variance.When calculating variance, also to calculate C(δ) just can draw last result.Utilization is based on the restriction probability triple-time estimate method of genetic algorithm, overcome the deficiency of conventional 3 o'clock methods of estimation, then suppose that operation duration obedience Beta distributes, in conjunction with limiting the probability triple-time estimate method, set up match variance least model, and use genetic algorithm to calculate model, result of calculation is calculated for the operation expected duration the most at last, can reduce the error in estimation in conventional 3 o'clock and distribution function deterministic process thereof, and is significant to improving the PERT network planning technique.

Summary of the invention

Technology of the present invention is dealt with problems and is: overcome existing aircraft regular inspection process optimization mainly based on working experience, lack the deficiencies such as theory support method, utilization, based on the expected duration of the triple-time estimate method approximate evaluation flow process operation of genetic algorithm, proposes a kind of regular inspection of aircraft based on probabilistic network scheduling technology flow optimization method.

Technical solution of the present invention is:

1, a kind of regular inspection of aircraft based on probabilistic network scheduling technology flow optimization method comprises the following steps:

(1) aircraft regular inspection flow process probabilistic network scheduling figure builds;

(2) aircraft regular inspection flow process probabilistic network scheduling deterministic;

(3) aircraft regular inspection flow process deterministic network planning optimization.

2, the aircraft regular inspection flow process probabilistic network scheduling figure in described step (1) is take the time as basis, with form the walking abreast and vivid the showing of Serial Relation interdependence between each operation in whole flow process, mutual restriction of network.

3, the aircraft regular inspection flow process probabilistic network scheduling deterministic in described step (2) is the uncertainty for each operation duration, utilizes the expected duration of determining operation based on the restriction probability triple-time estimate method of genetic algorithm.

4, the optimization of the determinacy network planning in described step (3) concrete steps are:

1. in input step (2), walking abreast of each operation is input to the Matrix Form of PERT_CPM module with parameters such as Serial Relation and expected durations, builds work (Activity) information slip of aircraft regular inspection flow process.

2. utilize the Solve and Analyze of PERT_CPM module, determine the parameters such as completion date and critical path.

Principle of the present invention: traditional aircraft regular inspection flow process is mainly carried out based on maintainer's experience and data, and theoretical property is not deep enough, systematicness is comprehensive not; In the probabilistic network scheduling optimization problem, the duration of each operation and variance computing formula fixed single, can not embody the statistical property of different operation duration, can not change with actual conditions; Ignored the impact of each professional collaborative work on time between predetermined repairs in regular inspection work, there is deviation the operation duration of calculating.So the present invention is directed to the uncertainty of each operation duration in flow process, the duration parameter of operation is determined in employing based on the restriction probability triple-time estimate method of genetic algorithm, and then utilize deterministic network planning optimization software optimization aircraft regular inspection flow process, improve the isoparametric estimated accuracy of critical path and completion date, strengthened the engineering operability of process optimization.

In the probabilistic network scheduling optimization problem, be converted in deterministic network planning optimization process, the duration parameter of each operation in most important definite network planning, the method of traditional definite operation duration is triple-time estimate method, more fast convenience, weak point is that its assumed condition and parameter value requirement are too harsh, is difficult to reflect changeable, uncertain realistic problem; Utilization method of estimation during based on the restriction probability three of genetic algorithm, can effectively utilize available data, the accurate parameter of the Beta distribution function of match operation, and then estimate duration of operation.

Contrast several improved triple-time estimate methods and 5 o'clock estimations technique, the operation duration expectation value that the method is calculated and the error of variance are all large and make the task duration of calculating less than normal; Under Equations of The Second Kind Beta distribution occasion, α, the β value is determined.The value of these two parameters is in case definite, and the concrete shape that Beta distributes is also just determined.So not only likely its mode is inconsistent with the most probable value that provides, and can't embody the environmental difference characteristic between each operation when processing practical problems.The restriction probability triple-time estimate method that the present invention is based on genetic algorithm is carried out the expected duration of calculation process, improves estimated accuracy, the enhancement engineering operability.

Due to Beta distribution function expression formula complexity, from resolving angle, be difficult to solve, can adopt genetic algorithm to obtain the satisfactory solution that meets accuracy requirement by appliance computer, improve search efficiency, speed and precision.

The present invention's advantage compared with prior art is: utilize the parallel and Serial Relation of each operation in probabilistic network scheduling technical Analysis regular inspection flow process, overcome the blindly deficiency of poor efficiency of traditional regular inspection process optimization; Restriction probability triple-time estimate method based on genetic algorithm, determining the duration parameter of each operation in the regular inspection flow process, is the deterministic network planning optimization by the probabilistic network scheduling transformation, more traditional triple-time estimate method and 5 o'clock estimations technique, estimated accuracy is high, and the engineering operability is stronger; Use the PERT_CPM module of WinQSB software to be optimized aircraft regular inspection flow process, determine the parameters such as the critical path of aircraft regular inspection work and completion date, high than other optimized algorithm efficiency, speed is fast, solving precision is high.

The accompanying drawing explanation

Fig. 1 is the regular inspection of the aircraft based on probabilistic network scheduling technology process optimization process flow diagram of the present invention;

Fig. 2 is uncertain aircraft regular inspection flow network planning chart, 1. jack-up aircrafts assign instruction in figure, 2. energising checks, 3. oil transportation sequential search, fuel dump checks, fuel level gauge error price differential, 4. take off radome, 5. radar in situ detection, 6. energising checks, 7. radar signal detecting, 8. antenna panel IFF oscillator checks, 9. dress radome, 10. put oxygen, 11. flap seat hatchcover, 12. flap seat chair, 13. extract, 14. aircraft warehouse-in, 15. jack-up aircraft, 16. ordnance professional work, 17. mechanical major work, 18. ad hoc professional work, 19. avionics professional work, 20. mechanism checks, 21. tear ejection guns open, 22. tear the gun overhaul open, 23. tear undercarriage annex verification open, 24. tear hydraulic system annex verification open, 25. tear fuel system annex verification open, 26. inspection yaw rudder, 27. tear the cold gas system annex open, 28. tear environmental control system annex verification open, 29. the airframe structure position checks, 30. angle of attack stagnation temperature angular displacement sensor detects, 31. total static-pressure system detects, 32. environmental control system inspection, 33. engine electrically systems inspection, 34. indicating instrument inspection, 35. boat appearance system detects, 36. oxygen system detects, 37. air data system detects, 38. the radar equipment cabin is detected, 39. Wave guide system detects, 40. passenger cabin inspection, 41. the radar impermeability detects, 42. sideslip sensor detects, 43. the radar air pipeline checks, 44. each mechanism's airtight test, 45. overhaul, 46. recover gun and check, 47. annex flaw detection, 48. installation recovers, 49. installation recovers, 50. coordinate the associating folding and unfolding, 51. coordinate the associating folding and unfolding, 52. associating folding and unfolding, 53. handle the stick force inspection, 54. undercarriage control, 55. flap folding and unfolding, 56. Nose Wheel Steering subtracts pendulum, 57. movable wing aperture measurement, 58. put down aircraft, 59. wheel braking inspection, 60. fill canopy and carry out the supercharging inspection, 61. oil cooling gas is filled, 62. filling oxygen energising check, 63. prepare before test run, 64. test run checks aircraft and engine state parameters, 65. the radar high pressure checks, 66. each specialty energising checks, 67. aircraft is always examined, 68. fill in card, log book, 69. surrender aircraft.

Fig. 3 is determinacy aircraft regular inspection flow network plan input figure, in figure, the working condition table comprises operation sequence number (Activity Number), operation title (Activity Name), tight front operation (Immediate Predecessor), expected duration (Normal Time) etc.;

Fig. 4 is determinacy aircraft regular inspection flow network plan output map, time parameter result of calculation in figure, comprise earliest start time (Earliest Start), earliest finish time (Earliest Finish), late start time (Lastest Start), latest finishing time (Lastest Finish), key node (On Critical Path), critical path number (Number of Critical Path (s)) of the time (Project Completion Time) that activity time (Activity Time), task complete, every operation etc.

Embodiment

Below utilize the aircraft regular inspection flow optimization method of probabilistic network scheduling technology of the present invention to carry out the process optimization of 400 ± 20h regular inspection to aircraft, Optimizing Flow as shown in Figure 1.

(1) aircraft regular inspection flow process probabilistic network scheduling;

Analyze the parallel and Serial Relation of each inter process of regular inspection flow process, determine aircraft 400 ± 20h regular inspection flow process probabilistic network scheduling figure as shown in Figure 2.

(2) utilize the restriction probability triple-time estimate method based on genetic algorithm, determine the expected duration of each operation in probabilistic network scheduling figure;

Network planning technique is applied to the process optimization of aircraft regular inspection, considers the impact of complicated factor, and is too many because of uncertain factor, needs to utilize the expected duration of estimating each operation.

Beta distributes estimated it is the duration obedience Beta distribution of hypothesis operation at 3 o'clock, and the distribution function that Beta distributes is shown below:

$f\left(x\right|\mathrm{\α},\mathrm{\β})=\frac{\mathrm{\Γ}(\mathrm{\α}+\mathrm{\β})}{\mathrm{\Γ}\left(\mathrm{\α}\right)\mathrm{\Γ}\left(\mathrm{\β}\right)}\frac{{(x-\mathrm{\α})}^{\mathrm{\α}-1}{(b-x)}^{\mathrm{\β}-1}}{{(b-a)}^{\mathrm{\α}+\mathrm{\β}-1}},(a\≤x\≤b,\mathrm{\α}>0,\mathrm{\β}>0)$

PERT average and the variance of each operation are:

$E\[X|a,m,b\]=\frac{\mathrm{\α}}{\mathrm{\α}+\mathrm{\β}}b+\frac{\mathrm{\β}}{\mathrm{\α}+\mathrm{\β}}a$

$V\left[X\right|a,m,b]=\frac{\mathrm{\α\β}}{{(\mathrm{\α}+\mathrm{\β})}^2(\mathrm{\α}+\mathrm{\β}+1)}{(b-a)}^2$

$M=\frac{\mathrm{\α}-1}{(\mathrm{\α}+\mathrm{\β}-2)}b+\frac{\mathrm{\β}-1}{(\mathrm{\α}+\mathrm{\β}-2)}a$

According to the theory of Malcolm, the value accurately estimating optimistic time that an operation completes, most likely time, pessimistic time, be estimated as respectively a, m, b tri-values, and its expectation value and variance can be estimated with following formula

$E\left[X\right|a,m,b]=\frac{a+4m+\mathrm{<figure-callout\; id="6"\; label="b"\; filenames="2013103098596100003DEST\_PATH\_IMAGE002.png,DEST\_PATH\_IMAGE003.png"\; state="\{\{state\}\}">b</figure-callout>}}{6}$

$V\left[X\right|a,m,b]=\frac{{(b-a)}^2}{36}$

Whether accurate duration expectation and the variance that will directly affect each operation in uncertain network of each operation PERT average and variance, and the expectation of operation duration and variance directly affect the final calculation result that the PERT method solves the uncertain network plan.While estimating practical application at 3 o'clock, often there are the problems such as estimation standard disunity, estimated accuracy be poor, thereby cause the Completion Probability error calculated large; And Beta distributes and to have the characteristics such as fitness is strong, can be similar to the multiple important distribution of match, as normal distribution, be uniformly distributed, triangle distribution, rayleigh distributed, trapezoidal profile etc.From the mathematical statistics angle, the PERT method is set total duration Normal Distribution of task according to central limit theorem, but on critical path, each operation duration can not meet the independent identically distributed hypothesis of central limit theorem, and this will cause net result certain error to occur.

For reducing the error in triple-time estimate method and distribution function deterministic process thereof, take based on the duration that limits probability triple-time estimate method estimation operation definition B (t _i)=λ _i, i.e. t _iFor fraction is λ _iThe time the operation duration.Utilize this definition, estimate that (a, m, b) is improved to and certain fraction λ to 3 o'clock _i=(λ ₁, λ ₂, λ ₃) corresponding operation duration estimation t _i=(t ₁, t ₂, t ₃).

Definition

For fraction λ _iCorresponding time t _iThe Beta match variance of estimating.

Beta fitting of distribution model: suppose to exist a β (a, b, α, β) distribution match preferably to limit probability λ _i=(λ ₁, λ ₂, λ ₃) corresponding time Estimate t _i=(t ₁, t ₂, t ₃); Take Z=min(Δ ζ) as objective function, seek suitable a, b, α, the β parameter makes match variance minimum, thereby determines that β (a, b, α, β) distributes.

Due to Beta distribution function expression formula complexity, from resolving angle, be difficult to solve, can adopt genetic algorithm to obtain the satisfactory solution that meets accuracy requirement.Then substitution formula

$E\&lsqb;X|a,m,b\&rsqb;=\frac{\mathrm{\&alpha;}}{\mathrm{\&alpha;}+\mathrm{\&beta;}}b+\frac{\mathrm{\&beta;}}{\mathrm{\&alpha;}+\mathrm{\&beta;}}a$

Obtain the expected duration of operation.

(3) on the basis of step (2), the probabilistic network scheduling optimization problem is converted to deterministic network planning optimization problem, use the PERT_CPM module of WinQSB software to be optimized aircraft 400 ± 20h regular inspection flow process.

1) each working procedure parameter of input aircraft 400 ± 20h regular inspection flow process

The fundamental of PERT key element-programme evaluation and review technique comprises: task, operation, node.

Task: usually a relatively independent engineering is called to a certain " task ".Regular inspection is keeped in repair, and it is exactly the beginning of task that regular inspection unit receives an airplane preparation regular inspection, and it is exactly the end of regular inspection task that aircraft recovers flight.

Operation: the task of aeronautical maintenance, complete from start to finish, be all a process of progressively making progress along with passage of time.In this flow process, comprised big and small classification work, also can be called " operation ", and standard may be different with requirement.If each part operation comprises specific many sub-operations, can be referred to as " separability " of operation.A lot of operations all may be segmented step by step, until implement to it concrete staff.But, consider and the operability of regular inspection project management system make the sub-operation of segmenting have certain logicality as far as possible.

Node: with regard to aeronautical maintenance, every maintenance procedures all can have instantaneous that start to do instantaneous and sign complete, for example preparation tool and check instrument.Certain maintenance procedures only have one tight before during operation, tight before operation complete instantaneous be exactly this operation start instantaneous.If several tight front operations are arranged simultaneously, after so all tight front operations all complete, the instantaneous just arrival that this operation starts to carry out.This is instantaneous as the interface point between operation and operation, is called " node ".Node may have obvious sign, such as signing documents; Also sign not, need to drain the oil and refuel while such as the fuel system inspection, indicating, and refueling and draining the oil is two continuous operations, between do not need to join content, as just the differentiation of two different operations.

According to serial and the concurrency relation between each operation in network planning figure, carry out each operation working condition table of aircraft 400 ± 20h regular inspection flow process, and determine the expected duration of each operation.

As shown in Figure 3, the work of aircraft 400 ± 20h regular inspection has 69 operations, by four specialties, is completed, and in the parameter of input, needs to determine logical relation and the expected duration of each operation.

The time parameter of part operation is as shown in table 1:

The time parameter of table 1 part operation

2) aircraft 400 ± 20h regular inspection flow process is optimized, determines the parameters such as the critical path of Optimizing Flow and completion date

Network planning figure is also referred to as network chart, is used for every operation and the logical relation between them in the expression task.Use network chart and computing time parameter, can find out calculated critical path, thereby implement more effective monitoring when plan is carried out.

From start node, along the direction of arrow, pass through continuously a series of arrows and node, the path that finally arrives terminal node is called path.Each paths has the deadline of oneself determining, it equals the summation of work in every duration on this path, has been also the plan time of all working on this paths, and it is long that this duration also can be described as road.The size long according to road, path can be divided into critical path, inferior critical path and non-critical path.The longest long path, road is called critical path.The all working that is positioned on critical path is called key job.The speed that key job completes is the realization of the whole task duration of impact directly.Road length is only second to the long path of critical path pathway, is called time critical path.Other all paths except critical path, inferior critical path all are called non-critical path.

1. according to key job, determine critical path

Key job is connected successively and the path that forms is exactly critical path.The length of critical path is calculated term of works, namely we usual said main duration.

2. according to key node, determine critical path

The earliest time of every node equates with latest time, or the difference of latest time and earliest time equals the difference of plan time and calculated term of works, and this node is called as key node.Node on critical path must be key node, and key node is not necessarily on critical path.Therefore, only with key node, can't determine critical path.When a key node is connected with a plurality of key nodes, to its connecting line, need be differentiated one by one according to the principle of maximum path.

3. according to free float, determine critical path

The free float of key job is necessarily minimum, but not necessarily key job of the work of free float minimum.If from start node, along the direction of arrow to terminal node till, the free float minimum of all working, this path is critical path, otherwise is not just critical path.

the PERT_CPM module is according to the parameter information of each operation of input, the parameters such as the critical path of generation Optimizing Flow and completion date, as shown in Figure 4, comprise activity time (Activity Time), task completion date (Project Completion Time), the earliest start time of every operation (Earliest Start), earliest finish time (Earliest Finish), late start time (Lastest Start), latest finishing time (Lastest Finish), key node (On Critical Path), critical path number (Number of Critical Path (s)) etc.

Show as calculated: 400 ± 20h regular inspection work deadline has shortened 840 minutes, and saving time is 15.3%, has improved the efficiency of regular inspection work.Optimization method provided by the invention improves aeronautical maintenance personnel's work efficiency, reduce the aircraft grounding time, for the collection of regular inspection data has indicated direction, not only can be used for the process optimization of military civil aircraft regular inspection simultaneously, also can be used for the periodic maintenance process optimization of other equipment.

By the aircraft regular inspection flow optimization method of probabilistic network scheduling technology provided by the invention, some conclusions of aircraft regular inspection process optimization have been obtained.

(1) network planning technique is more satisfactory to aircraft regular inspection process optimization effect.

(2) utilize the restriction probability triple-time estimate method based on genetic algorithm, can approximate exact estimate the expected duration of each operation in aircraft regular inspection flow process, the probabilistic network scheduling optimization problem is converted to deterministic network planning optimization problem.

(3) the PERT_CPM module of WinQSB software can solve the deterministic network optimization problem, determines the parameters such as critical path in aircraft regular inspection flow process and completion date.

Claims (4)

1. the regular inspection of the aircraft based on probabilistic network scheduling technology flow optimization method is characterized in that: comprise the following steps:

(1) aircraft regular inspection flow process probabilistic network scheduling figure builds;

(2) aircraft regular inspection flow process probabilistic network scheduling deterministic;

(3) aircraft regular inspection flow process deterministic network planning optimization.

2. the regular inspection of the aircraft based on probabilistic network scheduling technology flow optimization method according to claim 1, it is characterized in that: the aircraft regular inspection flow process probabilistic network scheduling figure in described step (1) is take the time as basis, with form the walking abreast and vivid the showing of Serial Relation interdependence between each operation in whole flow process, mutual restriction of network.

3. the regular inspection of the aircraft based on probabilistic network scheduling technology flow optimization method according to claim 1, it is characterized in that: the aircraft regular inspection flow process probabilistic network scheduling deterministic in described step (2) is the uncertainty for each operation duration, utilizes the expected duration of determining operation based on the restriction probability triple-time estimate method of genetic algorithm.

4. the regular inspection of the aircraft based on probabilistic network scheduling technology flow optimization method according to claim 1 is characterized in that: the determinacy network planning in described step (3) is optimized concrete steps and is:

1. in input step (2), walking abreast of each operation is input to the Matrix Form of PERT_CPM module with parameters such as Serial Relation and expected durations, builds work (Activity) information slip of aircraft regular inspection flow process.

2. utilize the Solve and Analyze of PERT_CPM module, determine the parameters such as completion date and critical path.

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