4 modern breakdowns diagnosis development tendency
4.1 analyzes -odd management
The modern -odd management to synthesizes Yu Du from hardware Yu
Du and analyzes -odd management development. In the past, the
dynamic system fault-tolerant design was, like three and four systems
which based on hardware -odd (-odd part, -odd system) realized,
through simple vote logic diagnosis. Hardware -odd (management)
( hardware redundancy) meets the main question is the
weight big, the volume big, the expense high, the flight vehicle
bearing capacity is small. Simultaneously "similar" -odd system
has the same life cycle, if has breakdown possibly other also to break
down. But uses "the different races" -odd system to guarantee
the vote examination with difficulty the uniformity. In order to
cause the overall system reliable, to be safe, also the enhancement
fault-tolerant system may the use, therefore has the necessity to
study the new method to eliminate or to reduce hardware -odd.
Enters for the 70's, along with the computer technology and its
the computation ability, the reliable enhancement, the modern control
theory production and the development, appeared has analyzed the
redundancy (analytical redundancy) to substitute for
physics (hardware) the redundancy -odd reliability design and -odd
management thought. First (IFD) center appeared this new way in
the measuring appliance failure detection, its thought is with 3 or
above not the similar sensor measurement system different variable,
produces the completely different signal, examines the sensor
breakdown through a complex synthesis comparison logic. Although
is the different races sensor, but all all is by the system in the
identical dynamic condition drive, therefore has some kind of function
relations. This new way initial period is called essential -odd
(inherent redundancy) or function -odd (functional redundancy), distinguishes between physical Yu Duhuo
hardware -odd. Afterwards the people were called it analyze Yu
Duhuo artificial -odd (artifical redundancy).
Analyzes -odd way is a use state estimation, the parameter
estimate, the adaptive filtering, the variable threshold value logic,
the statistical decision-making theory and the synthesis logic signal
processing technology, may realizes on the electronic circuit or the
computer. At present implements -odd management way or a
synthesis way, namely includes hardware Yu Du and analyzes -odd.
The development direction analyzes Yu Du. In 1971 Beard
proposed for the first time the failure detection filter (FDF) the
concept, symbolizes based on the analysis redundancy (based on model)
the breakdown diagnosis technology birth.
4.2 credible system design
The modern breakdown diagnosis is because implements initiative
(regards sentiment) to service the strategy and the establishment
supervisory system needs to develop. Because the modern
mechanical and electrical automation and the control system scale
unceasingly expands, the complexity enhances day by day, as well as
system investment hugeness, the people are urgent need to enhance
mechanical and electrical automated and the control system
credibility. Thus has the necessity to establish a supervisory
system to supervise the entire automated system the running status,
unceasingly examines the system the change and the breakdown
information, then takes the essential measure (for example isolation
and repair or change control rate and so on) prevents the breakdown
the dissemination and the disaster accident occurrence. But its
prerequisite is has the on-line real-time reliable examination and the
diagnosis breakdown ability. Therefore the breakdown diagnosis
realizes the credible system design essential link. The credible
system refers to the collection reliability, the validity, may
维修?and the security be a body system. Enhances the system
credible method, namely design credible system method: (1)
Enhances Yuan part itself the reliability; (2) Uses
-odd system (part), like hardware, software and compound redundant
structure; (3) Uses based on FDIA fault-tolerant and
control system and so on monitoring.
The lowest level is controls the level, the function is realizes
the input output and each kind of control rate; The intermediate
level function is examines the sensor, the driver, the control loop
and the control rate center malfunction; The topmost story
function is the condition - event logic, namely accepts carries out
the measure from the detector input and the output.
Based on FDIA fault-tolerant, monitoring control system
realization process: (1) Breakdown (expiration) 模 and
influence analysis (FMEA); (2) Affects the strict specific
weight appraisal; (3) Repair, remedial treatment
inferential reasoning; (4) The breakdown repair design
(revision control level, changes to other control 模, control
system heavy construction); (5) Counter FMEA process;
(6) The system modelling (analyzes -odd method failure
detection foundation); (7) Fault detector design;
(8) Supervisory system logical design.
4.3 Lu good breakdown diagnosis
Breakdown diagnosis robustness is the important question which
all breakdowns diagnosis theory, the method and the system faces.
The Lu good breakdown diagnosis (RFD) the concept in proposed
for the first time based on in the model breakdown diagnosis method.
At present can Zha Dao Lu good breakdown diagnosis research all
be based on the control system mathematical model. Specially
must point out is in the entire mechanical system, including hydraulic
system, hydraulic control system, but also has not seen the Lu good
breakdown diagnosis the research report.
Based on model Lu good breakdown diagnosis research beginning to
the beginning of 80's. After several years research and the
development, proposed many methods, also has conducted some applied
researches, the domestic some scholars also once have done the
beneficial research in the RFD aspect. Generally speaking, RFD
or a new research direction, waits for the thorough research.
Based on the artificial nerve network breakdown diagnosis,
domestic and foreign has already done many research in this aspect.
Although ANN has the principle robustness in the network
topology, but its BP study algorithm right and wrong robust. Can
Zha Dao material look on at present that, studied the algorithm to Lu
Bang the research just to start, to ask the BP algorithm non- robust
question and the key to the situation, but did not have the effective
Lu good algorithm, not yet saw the literature report to the Lu good
breakdown diagnosis research.
RFD solves the breakdown diagnosis practical application
effective way, is enhances the breakdown diagnosis system performance
target the effective way, simultaneously will have the novel effective
breakdown diagnosis theory and the method.
5 future research directions
At present and the next main research might induce into
following several aspects: (1) On-line real-time failure
detection algorithm; (2) Essential non-linearity dynamic
system FD method. The main research gains its condition, the
parameter effective method; (3) And the element of
certainty does not have the robust to the model error FD algorithm;
(4) The Lu good residual error generator and the Lu stick
(are most superior, auto-adapted) the threshold value design theory
and the method; (5) To does not have 先验知识 when by
supervisory system structural change examination and recognition;
(6) Real-time FD expert system development and with based
on ANN method, model method FD method synthesis; (7)
Intelligence failure detection and diagnosis system theory and
method research. From study examination system; (8)
Take FDIA as the core fault-tolerant control, the supervisory
system and the credible system.
To the failure detection, diagnoses said that, makes concrete
must vigorously study in the below aspect: (1) Feedback
system (closed-loop system) center breakdown diagnosis; (2)
Small peak-to-peak value breakdown, soft breakdown and early
breakdown examination; (3) In execution, process and
sensor breakdown diagnosis; (4) Besides 突变?
breakdown breakdown early forecast, namely forecast diagnosis;
(5) In dynamic system on-line real-time failure detection;
(6) System transition (transient) in process examination
and transient process failure detection; (7) Dynamic
system initiation and in conclusion process failure detection;
(8) (Lu Bang, auto-adapted) threshold value choice and
determination.
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