Brief definition of technical diagnostics. Basics of technical diagnostics

Equipment– a collective term that includes machines, units, mechanisms, assemblies, as well as apparatus, columns, installations, technological lines, electrical and thermal facilities, networks, technological and piping pipelines and other devices used in the production of products and performing certain functions other technological functions. Examples of equipment: energy, mechanical, electrical, chemical, engineering.

The term “unit” has two readings:

1. Unit is a structural unit that performs a closed cycle in the general formulation of the problem. For metallurgical enterprises, this is a set of machines, mechanisms, devices and structures connected by a single technological process. Examples: blast furnace, electric furnace, ladle furnace, rolling mill, etc.
2. Unit– an assembly unit that has the properties of complete interchangeability, independent assembly and independent performance of a certain function in products for various purposes, for example, a converter lance, an electric motor, a gearbox, a pump, etc.

Car– a set of mechanisms designed to perform useful work related to the process of production, transportation, transformation of energy or information. Examples: a machine for opening a cast iron tap hole, a casting tap, etc.

Mechanism– a system of kinematically connected units and parts designed to transform the type of movement. Examples: gearbox, crank mechanism, screw drive, etc.

Knot- a product whose components are connected to each other at the manufacturer. This is an assembly unit, assembled separately from other components of the product or the product as a whole, capable of performing a specific function in products for one purpose only together with other components. The term corresponds to an assembly as a piece of mechanical equipment, including a detachable or permanent connection of several parts. Examples: bearing, drum assembly, conveyor roller, etc.

Detail– a product made from one brand of material without the use of assembly operations. This is a product manufactured as one whole, the division of which into parts is impossible without damage. Examples: shaft, nut, bolt, blade, gear, etc.

Stages of machine existence

Stages of machine existence: design, manufacturing and operation. The ideas and properties laid down by designers and machine builders are implemented and manifested at the operation stage.

Exploitation– the totality of all phases of the existence of equipment from the moment it is registered on the balance sheet until it is written off, including periods of storage, transportation, intended use and all types of maintenance and repair.

Storage– a set of measures to protect against the destructive effects of the external environment and destaffing. Audit– a set of works to determine the degree of wear of the product to determine the required volume of repair work. Assembly– a set of works to recreate a product from its component parts. Installation– a type of assembly operations performed using lifting machines to install the product in place. Setup– bringing actual deviations of operating modes into compliance with standard ones. Disassembly– dismemberment of the product into its component parts.

Maintenance– a set of operations to maintain the functionality or serviceability of a product. May include: washing, monitoring technical condition, cleaning, lubrication, fastening threaded connections, replacing components, adjustment.

Maintenance– repairs performed to ensure or restore the functionality of a product by replacing or restoring individual parts. Major renovation– repairs carried out to restore serviceability and close to full restoration of the service life of a product with the replacement of its parts, including basic ones.

Scheduled repairs– repairs, stopping for which is carried out in accordance with the requirements of regulatory and technical documentation. Unscheduled repairs– repairs carried out without prior appointment. Regulated repairs– planned repairs performed at intervals and to the extent established by the operational documentation. Repair according to technical condition– planned repairs, the scope and timing of which are determined by the technical condition of the product.

Types of technical condition

Working condition– the state of an object in which it is capable of performing all the specified functions of the object.

Faulty condition– a state of an object in which it is unable to perform at least one of the specified functions of the object. A malfunction is often a consequence of an object failure, but can also occur without it.

Operating state– the state of an object in which it is capable of performing all required functions.

Inoperative state– the state of an object in which it is unable to perform at least one of the required functions.

Critical condition– a condition of the facility that may lead to injury to operating personnel, significant material damage, or other unacceptable consequences. A critical condition is not always the result of a critical failure. Criteria for critical condition must be established for a specific object.

Limit state– the state of an object in which its further operation is unacceptable or impractical, or restoration of its working condition is impossible or impractical. The limit state occurs when the failure flow parameter becomes unacceptable and (or) the object is considered beyond repair as a result of a malfunction.

The technical condition is determined by the presence and development of faults in the object. Types of faults:

• defect– each non-compliance of the object with the established requirements;
• damage– an event consisting in a violation of the serviceable state of an object, while maintaining the serviceable state.

The development of faults leads to failure.

Refusal– an event consisting in a violation of the operational state of an object, i.e., in the loss of the ability of the object to perform the required function. Failure is an event, as opposed to "failure", which is the state and cause of failure.

Crash– a self-correcting failure or a one-time failure that can be eliminated with minor operator intervention. This is an event in which, as a result of a temporary change in the parameters of an object, interference occurs that affects performance.

Depending on the need for maintenance and repair, the following are distinguished: technical condition categories:

• good– no maintenance or repair required;
• satisfactory– maintenance and repairs are carried out in accordance with the plan;
• bad– extraordinary maintenance or repairs are carried out;
• emergency– immediate shutdown and repair is required.

Technical diagnostics – an area of ​​knowledge about recognizing the state of technical systems (objects), exploring the forms of manifestation of the technical state, developing methods and means for its determination.

Technical system- a material object of artificial origin, which consists of elements united by connections and entering into certain relationships with each other and with the external environment in order to perform certain useful functions. The technical system must be controlled to obtain an effective result.

Control is the process of receiving, storing and processing information to organize targeted actions.

Technical diagnostic service– a division that provides the technical services of the enterprise with information about the technical condition, prognosis and reasons for the occurrence of this condition.

Diagnosis– operations carried out to determine the presence of a malfunction and determine the causes of its occurrence.

Diagnosis of the technical condition of the object is carried out diagnostic tools(hardware and software).

Diagnostic tools and objects interacting with each other form diagnostic system.

The result of diagnosis is diagnosis, which determines the technical condition - identifying a malfunction in an object and assigning the object to a certain category of technical condition. Diagnosis is carried out in accordance with the developed algorithm.

Algorithm for technical diagnostics (monitoring of technical condition) – a set of instructions that determine the sequence of actions when carrying out diagnostics or control. In general, an algorithm is a sequence of actions built according to certain rules to achieve a set goal.

Technical diagnostic tasks

1. Determining the state in which an object is currently located.
2. Determining the state in which an object will find itself is a forecast task necessary to determine the timing of diagnosis and repair.
3. Determining the state in which the object was located is a task of genesis, used to determine the causes of failure and the development of damage.

The main objectives of technical diagnostics as a science are:

• determination of the technical condition of the diagnostic object in conditions of limited information;
• studying methods and means of obtaining diagnostic information;
• development of algorithms for automated control and detection of defects;
• minimizing diagnosis .

Technical diagnostics studies methods for obtaining and evaluating diagnostic information, diagnostic models and decision-making algorithms. Technical diagnostics is based on two theories: recognition theory and testability theory ().

Recognition theory, using diagnostic models when examining an object, determines the decisive rules for recognizing the current state and type of malfunction. Thanks to the known characteristics of faults, it becomes possible to develop optimal recognition algorithms (sequences).

Traceability theory solves issues of a rational sequence of searching for a failed or faulty element, monitoring the condition of an object. Decisions are based on the use of diagnostic information characterizing the state of the object.

Traceability– the adaptability of the object to the measurement of diagnostic parameters by diagnostic means, the ability of the product to provide a reliable assessment of the technical condition and early detection of malfunctions and failures. Controllability is created by the design of the product and the adopted technical diagnostic system.

Diagnostic model– a formalized description of the technical diagnostic object necessary for solving diagnostic problems. Description forms: analytical, tabular, vector, graphic.

Diagnostic parameter– a parameter (attribute) of an object that quantitatively or qualitatively characterizes the technical condition of the object. Diagnostic parameters have the following gradations: nominal, maximum permissible, maximum possible, emergency.

The main task of diagnosing– obtaining information about the technical condition of the object.

Standard definition according to GOST 20911-89 “Technical diagnostics. Terms and definitions": "The technical condition is characterized at a certain point in time, under certain environmental conditions, by the values ​​of the parameters established by the technical documentation for the object."

Definition of technical condition according to GOST 19919-74: “Technical condition is a set of properties of an object subject to production or operation, characterized at a certain moment by the signs established by the technical documentation for this object.”

Diagnostics is based on solving the problem of recognizing the technical condition of an object. The state of an object, in relation to mechanical equipment, is characterized by diagnostic parameters: input, output and internal ().

Input parameters– external conditions and control influences (rotation speed, applied torque, force, power, pressure, feed, speed). Output parameters(reactions) – parameters showing the behavior of an object (vibration, noise, temperature, uniformity of rotation, etc.). Internal parameters– parameters that determine the structure of an object and characterize the processes occurring inside it (dimensions of parts, gaps, roughness, distribution of forces and stresses, mechanical characteristics of the material, etc.).

The influence of input parameters when determining the technical condition must be eliminated by bringing it to standard conditions. This circumstance must be taken into account when carrying out measurements on test benches and in industrial conditions. Measurements of diagnostic parameters must be performed at a constant load.

Diagnostic parameters can be straight– directly reflecting the internal parameters of machines (torque, frequency and uniformity of rotation, gaps, surface roughness) and indirect– reflecting the relationship between internal and output parameters (physical fields: vibration, acoustic, thermal). When solving diagnostic problems, preference is usually given to indirect parameters due to the greater availability of measurements on operating equipment without disassembling the mechanism.

The process of functioning of a mechanism is determined not only by the internal properties of the elements of the mechanism. The performance of a mechanical system is influenced equally by the applied forces and the quality of maintenance. It is these three factors: the internal properties of the elements, the applied forces, the quality of maintenance and repair that determine the concept of technical condition (

LECTURE 1

FUNDAMENTALS OF THE THEORY OF TECHNICAL DIAGNOSTICS

1. General concepts and definitions

Technical diagnostic tasks

Technical diagnostics determines the state in which a technical object (device, system) is located.

Under the condition of a technical object is understood as the totality of its parameters(meanings of signals, ability to perform certain functions). Parameters are divided into basic (characterize the performance of specified functions by the system) and auxiliary (ease of use, appearance, etc.).

There are four types object states :

serviceable (the system meets all the requirements for it, i.e. all main and auxiliary parameters are within the specified norm);

faulty (the system does not meet at least one of the requirements for it);

workable (All the main parameters of the system are within the specified norm);

inoperative (at least one main parameter of the system does not correspond to the specified norm).

Definitions in set theory language:

Complete set of system states:

Where – set of serviceable states of the system;

– many faulty but operable states;

– many faulty and inoperable states.

Sets of states of functional and faulty systems, respectively

,

Systems are built in such a way that in case of all the most probable failures of its elements, transition from the set is impossible V , and the system would end up in a set (example: failure of route dialing in the MRC does not lead to loss of functionality).

An object whose technical condition is determined is calledobject of diagnosis .

Diagnosis there is a process of studying the object of diagnosis.Diagnosis result – this is a conclusion about the state of the object of diagnosis.

Types of tasks to determine the state of technical objects:

diagnosis – determination of the state in which the object is located at this moment in time(checking operability, serviceability, troubleshooting, testing the HATS);

forecast – state prediction, in which the object will find itself (operation of the residential telephone system, including determining the frequency of preventive maintenance and repairs);

genesis – determination of the state in which was technical object previously(determining the causes of failures);

When solving problems of prognosis and genesis, one always has to solve the problem of diagnosis.

Requirements for objects technical diagnostic studies:

may be in at least two mutually exclusive and distinguishable states (operational and inoperative, etc.);

in them it is possible to identify elements, each of which is subject to paragraph 1.

Diagnosis tasks :

Equivalent such malfunctions are called, which cannot be distinguished from each other using the accepted method of diagnosis.The number of classes that determines the granularity of the search is calledsearch depth (diagnosis)

T Esti and diagnostic systems

The object of diagnosis of OD is represented in the form of a device (see Fig. 1) that has inputs and outputs accessible for observation.

Diagnosis objects are divided into:

continuous (analog) (signal values ​​belong to continuous sets and time is continuous);

discrete (signal values ​​are specified on finite sets, and time is discrete);

hybrid .

In addition, ODs are:

combinational (without memory) (in them the output signal corresponds one-to-one to the combination of input);

sequential (with memory) (in them the output signal depends not only on the input values, but also on time).

Diagnosis process represents a sequence of operations (checks)
, each of which provides for the supply of a certain influence to the inputs of the object and the determination at the outputs (working or additional control) of the reaction to this influence.

Any diagnostic procedure is necessarily associated with a specific, strictly fixed list of faults, the detection of which is ensured during its implementation.

The set of checks that allow solving any of the diagnostic problems is called test :
, and the number of checks included in it is dough length .

The purpose of the tests is:

Completeness of fault detection is the proportion of guaranteed detected faults relative to all considered faults of the object.

Based on the completeness of fault detection, the following types of tests are distinguished:

By length, tests are divided into:

trivial – contain all possible checks for a given system, provide for complete simulation of the device’s operation and have a maximum length;

minimized (most common);

minimum – contains a minimal number of checks compared to other tests for this device, but requires large calculations.

The diagnostic procedure is based on algorithm , which represents totality sequence of elementary checks and rules for analyzing the results of these checks.

The diagnosis algorithm (measurement and analysis of responses, and sometimes the formation of test effects) is implemented by special devices - means of diagnosing diabetes . The object of diagnosis and the means of diagnosis interact with each other to form diagnosis system .

There are two types of diagnostic systems:

1.Test diagnosis systems . In them, the test effects of TV on OD come only from SD. These systems allow you to select the composition and sequence of test impacts based on the conditions for the effective organization of the diagnostic process, in particular, depending on the object’s responses to previous impacts.

2. Functional diagnosis systems do not form impacts on OA. The OD and SD receive only the working influences of the radioactive elements provided for by the working algorithm of the object’s functioning. The diagnostic system operates during the operational functioning of the OD and solves the problems of checking the correct functioning and troubleshooting.

Ultimately, the diagnosis procedure comes down to comparing the operation of an ideal device (set by the OD model) and the real device under study.

Thus, to carry out the diagnostic procedure, it is necessary to solve the following main goals :

selection and construction of an OA model;

test synthesis;

constructing a diagnosis algorithm;

synthesis and implementation of diagnostic tools.

2. Diagnosis object models

To construct tests and diagnostic algorithms, it is necessary to have a formal description of the object and its behavior in good and bad states - a mathematical model of diagnosis.

There are models with obvious And implicit description of faults.

Explicit model The diagnosis object consists of descriptions of its working and all faulty modifications.

Implicit model The diagnosis object contains a description of a serviceable object, mathematical models of its physical faults and rules for obtaining from them all faulty modifications of the object.

Fault Function Table (TFN) is a universal mathematical model of a diagnostic object (suitable for describing objects of any nature, both analog and discrete) and belongs to the class obvious models.

Drawing up a TFN table.

The table rows indicate all possible checks , which can be used in the diagnostic procedure. The table columns correspond to the correct and all possible fault conditions:
. Each faulty state corresponds to one fault (single or multiple) from a given class of faults, against which the test is constructed. At intersection -th graphs and the th line contains the result -th check for a system in the -th state.

Examination	Result checks for a system in state

Interdisciplinary connections: Supporting: computer science, mathematics, computer technology and MP programming systems. the patient's condition is determined by medical diagnostics; or the state of the technical system technical diagnostics. Technical diagnostics is the science of recognizing the state of a technical system. As is known, the most important indicator of reliability is the absence of failures during the operation of a technical system.

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Lecture 1

Subject. Basics of technical diagnostics

Target. Give the concept of the need for technical diagnostics for electronic systems.

Educational. Explain the concepts of basic diagnostics.

Developmental. Develop logical thinking and a natural - scientific worldview.

Educational . Cultivate interest in scientific achievements and discoveries in the telecommunications industry.

Interdisciplinary connections:

Supporting: computer science, mathematics, computer technology and MP, programming systems.

Provided: Internship practice

Methodological support and equipment:

Methodological development for the lesson.

Syllabus.

Training program

Working programm.

Safety briefing.

Technical teaching aids: personal computer.

Providing jobs:

Workbooks

Progress of the lecture.

Organizing time.

Analysis and checking of homework

Answer the questions:

Lecture outline

1 Basics of technical diagnostics

1.1 Main directions of technical diagnostics

1.2 Setting the tasks of technical diagnostics

1 MAIN AREAS OF TECHNICAL DIAGNOSTICS

Definitions. The term "diagnosis" comes from the Greek word "diagnosis", which means recognition, determination.

During the diagnostic process, a diagnosis is established, i.e., the patient’s condition is determined (medical diagnostics; or the state of the technical system (technical diagnostics).

Technical diagnostics is the science of recognizing the state of a technical system.

Objectives of technical diagnostics.Let us briefly consider the main content of technical diagnostics. Technical diagnostics studies methods for obtaining and evaluating diagnostic information, diagnostic models and decision-making algorithms. The purpose of technical diagnostics is to increase the reliability and service life of technical systems.

As is known, the most important indicator of reliability is the absence of failures during the operation (operation) of a technical system. Failure of an aircraft engine during flight conditions, ship machinery during a ship's voyage, or power plants operating under load can lead to serious consequences.

Technical diagnostics, thanks to the early detection of defects and malfunctions, makes it possible to eliminate such failures during the maintenance process, which increases the reliability and efficiency of operation, and also makes it possible to operate critical technical systems according to their condition.

In practice, the service life of such systems is determined by the “weakest” copies of products. During condition-based operation, each specimen is operated to its limiting condition in accordance with the recommendations of the technical diagnostic system. Condition-based operation can bring benefits equivalent to the cost of 30% of the total fleet.

Main tasks of technical diagnostics. Technical diagnostics solves a wide range of problems, many of which are related to the problems of other scientific disciplines. The main task of technical diagnostics isrecognition of the state of a technical system in conditions of limited information.

Technical diagnostics are sometimes called in-place diagnostics, i.e. diagnostics carried out without disassembling the product.State analysis is carried out under operating conditions in which obtaining information is extremely difficult. Often it is not possible to draw an unambiguous conclusion from the available information and statistical methods have to be used.

The general theory of pattern recognition should be considered the theoretical foundation for solving the main problem of technical diagnostics.This theory, which forms an important section of technical cybernetics, deals with the recognition of images of any nature (geometric, sound, etc.), machine recognition of speech, printed and handwritten texts, etc. Technical diagnostics studies recognition algorithms in relation to diagnostic tasks that are usually can be considered as classification problems.

Recognition algorithms in technical diagnostics are partly based ondiagnostic models,establishing a connection between the states of a technical system and their displays in the space of diagnostic signals. An important part of the recognition problem are decision rules (decision rules).

Solving a diagnostic problem (classifying a product as serviceable or faulty) is always associated with the risk of a false alarm or missing a target. To make an informed decision, it is advisable to use methodstheory of statistical decisions,developed for the first time in radar.

Solving technical diagnostic problems is always associated with predicting reliability for the next period of operation (until the next technical inspection). Here, decisions must be based on failure models studied in reliability theory.

The second important area of ​​technical diagnostics iscontrol theory.Controllabilityis the property of a product to provide a reliable assessment of its technical condition and early detection of faults and failures. Controllability is created by the design of the product and the adopted technical diagnostic system.

A major task of the theory of control capacity is the study of means and methods for obtaining diagnostic information. Complex technical systems use automated condition monitoring, which involves processing diagnostic information and generating control signals.Methods for designing automated control systems constitute one of the areas of the theory of controllability. Finally, very important tasks of the theory of controllability are associated with the development of fault finding algorithms, the development of diagnostic tests, and minimizing the process of establishing a diagnosis.

Due to the fact that technical diagnostics initially developed only for radio-electronic systems, many authors identify the theory of technical diagnostics with the theory of controllability (fault detection and monitoring), which, of course, limits the scope of application of technical diagnostics.

Structure of technical diagnostics. In Fig. 1 the structure of technical diagnostics is shown. It is characterized by two interpenetrating and interconnected directions: the theory of recognition and the theory of control ability. Recognition theory contains sections related to the construction of recognition algorithms, decision rules and diagnostic models. The theory of controllability includes the development of tools and methods for obtaining diagnostic information, automated control and troubleshooting. Technical diagnostics should be considered as a section of the general theory of reliability.

1.2 FORMULATION OF TECHNICAL DIAGNOSTICS TASKS

Introductory remarks. Let it be necessary to determine the condition of the spline connection of the gearbox shafts under operating conditions. When the splines are worn too much, distortions and fatigue damage appear. Direct inspection of the splines is impossible, since it requires disassembling the gearbox, i.e., stopping operation. A malfunction of the spline connection can affect the vibration spectrum of the gearbox housing, acoustic vibrations, iron content in the oil and other parameters.

The task of technical diagnostics is to determine the degree of spline wear (the depth of the destroyed surface layer) based on measurement data of a number of indirect parameters. As indicated, one of the important features of technical diagnostics is recognition in conditions of limited information, when it is necessary to be guided by certain techniques and rules to make an informed decision.

State of the systemis described by a set (set) of its defining parameters (features). Of course, the set of defining parameters (features) may be different, primarily in connection with the recognition task itself. For example, to recognize the state of an engine spline joint, a certain group of parameters is sufficient, but it must be supplemented if other parts are also diagnosed.

System State Recognitionassignment of the system state to one of the possible classes (diagnoses). The number of diagnoses (classes, typical conditions, standards) depends on the characteristics of the problem and the goals of the study.

Often it is necessary to select one of two diagnoses (differential diagnosis or dichotomy); for example, "good condition" and "faulty condition". In other cases, it is necessary to characterize the faulty condition in more detail, for example, increased wear of splines, increased vibration of blades, etc. In most technical diagnostic problems, diagnoses (classes) are established in advance, and in these conditions the recognition problem is often called a classification problem.

Since technical diagnostics is associated with the processing of a large amount of information, decision-making (recognition) is often carried out using electronic computers (computers).

The set of sequential actions in the recognition process is calledrecognition algorithm. An essential part of the recognition process isselection of parameters,describing the state of the system. They must be sufficiently informative so that, given the selected number of diagnoses, the separation (recognition) process can be carried out.

There are two main approaches to the recognition problem:probabilistic and deterministic. Formulation of the problemwith probabilistic recognition methods this is the case. There is a system that is located in one of P random states D. A set of characteristics (parameters) is known, each of which characterizes the state of the system with a certain probability. Required to builddecisive rulewith the help of which the presented (diagnosed) set of signs would be assigned to one of the possible conditions (diagnoses). It is also advisable to assess the reliability of the decision made and the degree of risk of an erroneous decision.

With deterministic recognition methods, it is convenient to formulate the problem in geometric language. If the system is characterized v -dimensional vector X, then any state of the system represents a point at v -dimensional space of parameters (features). It is assumed that diagnosis D corresponds to a certain region of the considered feature space. It is required to find a decision rule according to which the presented vector X* (the object being diagnosed) will be assigned to a specific area of ​​diagnosis. Thus, the task comes down to dividing the feature space into diagnosis areas.

With a deterministic approach, diagnosis areas are usually considered “non-overlapping”, i.e. the probability of one diagnosis (in which the point falls) is equal to one, the probability of others is zero. Similarly, it is assumed that each symptom is either present with a given diagnosis or absent.

Probabilistic and deterministic approaches have no fundamental differences. Probabilistic methods are more general, but they often require a significantly larger amount of preliminary information. Deterministic approaches more briefly describe the essential aspects of the recognition process, are less dependent on redundant, low-value information, and are more consistent with the logic of human thinking.

2 BASICS OF CONTROL AND TECHNICAL DIAGNOSTICS OF DIGITAL SYSTEMS

2.1. Basic concepts and definitions

One of the most effective ways to improve the operational and technical characteristics of digital systems that have taken a dominant position in modern telecommunication systems is the use of methods and means of control and technical diagnostics during their operation.

Technical diagnostics is a field of knowledgeallowing, with a given reliability, to separate faulty andthe serviceable state of systems and its purpose is to localize faults and restore the serviceable state of the system. WITHFrom the point of view of a systems approach, it is advisable to consider monitoring and technical diagnostic tools as an integral part of the maintenance and repair subsystem, i.e. the technical operation system.

Let's consider the basic concepts and definitions used fordescriptions and characteristics of monitoring and diagnostic methods.

Maintenance- this is a set of works (operations) formaintaining the system in good or working condition.

Repair - a set of operations to restore operability and restore the resources of the system or its components.

Maintainability- a property of a system that consists in its adaptability to preventing and detecting the causes of its failures and restoring an operational state through maintenance and repair.

Depending on the complexity and volume of work, the nature of the faults, two types of repair of digital systems are provided:

Unscheduled system maintenance;

Unscheduled average system repair.

Maintenance - repairs performed to ensure orrestoring system functionality and replacingor restoration of its individual parts.

Medium renovation - renovation, carried out to restore serviceability and partially restore service life with the replacement or restoration of components of a limited range and monitoring the technical condition of components, carried out in volume, established by regulatory and technical documentation.

One of the important concepts in technical diagnostics is the technical condition of an object.

Technical condition- a set of things subject to changein the process of production or operation of the properties of an object, characterized at a certain moment by the signs established by regulatory and technical documentation.

Technical condition monitoring- determination of the type of technical condition.

Type of technical condition- a set of technical conditions that satisfy (or do not satisfy) the requirements that determine the serviceability, performance or correct functioning of an object.

There are the following types of object state:

Good or bad condition

Functional or non-functional state,

Full or partial functioning.

Serviceable - technical condition in which the object meets all established requirements.

Faulty - technical condition in which the object does not meet at least one of the established regulatory requirements characteristics.

Efficient- technical condition in which the object is capable of performing specified functions, maintaining the values ​​of specified parameters within established limits.

Inoperative- technical condition in which the valueat least one given parameter characterizing the abilityobject to perform the specified functions, does not correspond to the established ones requirements.

Correct functioning- technical condition in which the object performs all those regulated functions that are required at the current moment in time, maintaining the values ​​of the specified parameters for their implementation within established limits.

Malfunction- technical condition, within which the object does not perform part of the regulated functions,required at the current time or does not save the values ​​of the specified parameters for their implementation within the established limits.

From the definitions of the technical states of an object it follows thatin a state of serviceability, an object is always operational, in a state ofoperability functions correctly in all modes, and in the malfunctioning state it is inoperable and faulty. A properly functioning object may be inoperative, and therefore faulty. A workable object can bealso faulty.

Let's look at some definitions related to the concepttestability and technical diagnostics.

Traceability- property of an object that characterizes itadaptability to carry out control by specified means.

Testability indicator- quantitative characteristics of testability.

Testability level- relative characteristictestability, based on a comparison of the set of testability indicators of the assessed object with the corresponding set of basic indicators.

Technical diagnostics- the process of determining the technical condition of an object with a certain accuracy.

Defect search - diagnostics, the purpose of which isdetermination of the location and, if necessary, the cause and type of defect.

Diagnostic test- one or more test actions and the sequence of their execution, ensuring diagnosis.

Validation test- diagnostic test to check the serviceability or performance of an object.

Defect search test- diagnostic test to find a defect.

Total fundsand the object of diagnosis and, if necessary, performers,prepared for diagnosis or performing it according to the rules established by the relevant documentation.

The result of the diagnosis is a conclusion about the technical condition of the object, indicating, if necessary, location, typeand the causes of the defect. The number of states that need to be distinguished inThe result of the diagnosis is determined by the depth of the fault search.

Troubleshooting depth- the degree of detail in technical diagnostics, indicating to what component of the object the location of the fault is determined.

2.2. Tasks and classification of technical diagnostic systems

Increasing requirements for the reliability of digital systems necessitate the creation and implementation of modernmethods and technical means of monitoring and diagnostics for variouslife cycle stages. As noted earlier, the transition to the widespread use of LSI, VLSI and MPC in digital systems has created, along with undeniable advantages, a number of serious problems in their operational maintenance, primarily related to control processesand diagnostics. It is known that the cost of troubleshooting at the production stage ranges from 30% to 50% of the totaldevice manufacturing costs. At the operational stage, at least 80% of the digital system recovery time is spent onsearching for a faulty replacement element. In general, the costs Related detection, troubleshooting and troubleshooting increase 10 times as the fault passes through each processstage and from input control of integrated circuits to identificationFailures during the operational phase are 1000 times more expensive. A successful solution to such a problem is possible only on the basis of an integrated approach to diagnostic control issues, since diagnostic systems are used at all stages of the life of a digital system. Thisrequires a further increase in the intensity of maintenance work,restoration and repair at the stages of production and operation.

General tasks of monitoring and diagnostics of digital systems and its components are usually considered from the point of view of the main stages of development, production and operation. Along with general approaches to solving these problems, there are also significant differences due to the specific features inherent in these stages.

At the stage of development of digital systems, two tasks are solvedcontrol and diagnostics:

1. Ensuring the testability of the digital system as a whole and its components.

2. Debugging, checking the serviceability and performance of componentsand the digital system as a whole.

When monitoring and diagnosing in the production conditions of a digital system, the following tasks are solved:

1. Identification and rejection of defective components and assemblies at early manufacturing stages.

2. Collection and analysis of statistical information about defects and types malfunctions.

3. Reducing labor intensity and, accordingly, the cost of control and diagnostics

Monitoring and diagnostics of a digital system under operating conditions have the following features:

1. In most cases, localization of faults atlevel of a structurally removable unit, usually a standard onereplacement element (TEZ).

2. There is a high probability that no more than one will appear by the time of repair. malfunctions.

3. Most digital systems have some possibilities control and diagnostics.

4. Early detection of pre-failure conditions is possible whenpreventive examinations.

Thus, for an object subject to technical diagnostics, the type and purpose of the diagnostic system must be established.

The following basic ones are installedareas of application of diagnostic systems:

a) at the production stage of the facility: during the adjustment process, during acceptance;

b) at the stage of operation of the facility; during maintenance induring use, during maintenance duringstorage, during maintenance during transportation;

c) when repairing a product: before repair, after repair.

Diagnostic systems are intended for solutions to one or several tasks: serviceability check; performance checks; Functional checks: searching for defects. Whereincomponents of the diagnostic system are: the object of technical diagnostics, which is understood as the object or itscomponents, the technical condition of which is subject to determination, means of technical diagnostics, a set of measuring instruments, means of switching and interfacing with the object.

Technical diagnostics (TD)is carried out in a technical diagnostic system (TDS), which is a set of diagnostic tools and objects and, if necessary, performers, prepared for diagnostics and carrying out it according to the rules established by the documentation.

The components of the system are:

object of technical diagnostics(OTD), which means systems or its components, the technical condition of which is subject to determination, andtechnical diagnostic tools- a set of measuring instruments, means of switching and interfacing with OTD.

Technical diagnostic systemworks in accordance with the TD algorithm, which represents a set of instructions for conducting diagnostics.

Conditions for carrying out TD, including the composition of diagnostic parameters (DP), their maximum permissible minimum and maximum pre-failure values, frequency of product diagnostics and operational parameters of the means used, determine the mode of technical diagnostics and control.

Diagnostic parameter(sign) - a parameter used in the prescribed manner to determine the technical condition of an object.

Technical diagnostic systems (TDS) can be different in their purpose, structure, installation location, composition, design, and circuit solutions. They can be classified according to a number of characteristics that determine their purpose, tasks, structure, and composition of technical means:

by the degree of coverage of OTD; by the nature of the interaction between the OTD and the technical diagnostics and control system (STDC); on the means of technical diagnostics and control used; according to the degree of automation of OTD.

According to the degree of coverage, technical diagnostic systems can be divided into local and general.By local we mean technical diagnostic systems that solve one or more of the tasks listed above - determining operability or finding the location of a failure. General refers to technical diagnostic systems that solve all diagnostic tasks.

Based on the nature of interaction between the OTD and technical diagnostic tools (SDT), technical diagnostic systems are divided into:

systems with functional diagnostics, in which the solution to diagnostic problems is carried out during the operation of the OTD for its intended purpose, and systems with test diagnostics, in which the solution to diagnostic problems is carried out in a special operating mode of the OTD by sending test signals to it.

According to the technical diagnostic tools used, TD systems can be divided into:

systems with universal meansTDK (for example, computer);

systems with specialized tools(stands, simulators, specialized computers);

systems with external means, in which the means and OTD are structurally separated from each other;

systems with built-in tools, in which OTD and STD constructively represent one product.

According to the degree of automation, technical diagnostic systems can be divided into:

automatic , in which the process of obtaining information about the technical condition of the technical condition is carried out without human participation;

automated, in which the receipt and processing of information is carried out with partial human participation;

manual(manual), in which the receipt and processing of information is carried out by a human operator.

Technical diagnostic tools can be classified in a similar way: automatic; automated; manual.

In relation to the object of technical diagnostics, diagnostic systems must: prevent gradual failures; identify hidden failures; search for faulty components, blocks, assembly units and localize the location of failure.

Homework: § notes.

Fixing the material:

Answer the questions:

1. What areas characterize the structure of technical diagnostics? Define each of them.
2. Explain the definition of "Recognition of system state",What determines the number of diagnoses?
3. What properties should parameters describing the state of the system have?
4. What is Technical Diagnostics?
5. What is maintenance?
6. What is meant by Equipment Repair?
7. What's happened Maintainability?
8. What types of digital system repairs are provided? Define each of them.
9. Explain the definition of “Technical condition”.
10. What types of object state are distinguished? Describe each of them.
11. Explain the termsCorrect functioning and Incorrect functioning.
12. What's happened Technical diagnostics?
13. What does it includeTechnical diagnostic system?
14. What tasks control and diagnostics are decided at the development stage?
15. What is a diagnostic parameter (sign)?
16. How are technical diagnostic systems divided by coverage?
17. How are technical diagnostic systems divided according to the nature of the interaction of STD with technical diagnostic tools (SDT)?

Literature:

Amrenov S. A. “Methods of monitoring and diagnostics of communication systems and networks” LECTURE NOTES -: Astana, Kazakh State Agrotechnical University, 2005

I.G. Baklanov Testing and diagnostics of communication systems. - M.: Eco-Trends, 2001.

Birger I. A. Technical diagnostics. M.: “Mechanical Engineering”, 1978.240, p., ill.

ARIPOV M.N., DZHURAEV R.KH., DZHABBAROV S.YU.“TECHNICAL DIAGNOSTICS OF DIGITAL SYSTEMS” - Tashkent, TEIS, 2005

Platonov Yu. M., Utkin Yu. G.Diagnostics, repair and prevention of personal computers. -M.: Hotline - Telecom, 2003.-312 p.: ill.

M.E.Bushueva, V.V.BelyakovDiagnostics of complex technical systems Proceedings of the 1st meeting on the NATO project SfP-973799 Semiconductors . Nizhny Novgorod, 2001

Malyshenko Yu.V. TECHNICAL DIAGNOSTICS part I lecture notes

Platonov Yu. M., Utkin Yu. G.Diagnostics of computer freezes and malfunctions/Series “Technomir”. Rostov-on-Don: “Phoenix”, 2001. 320 p.

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Significant costs for maintaining equipment are primarily due to the low quality of its maintenance and premature repairs. To reduce labor costs and funds for maintenance and repair, it is necessary to increase productivity and improve the quality of these works by increasing the reliability and serviceability (maintainability) of manufactured units, development and better use of the production and technical base of enterprises, mechanization and automation of technological processes, implementation diagnostic tools and elements of scientific organization of labor.

Under reliability understand the property of the machine components to perform specified functions, maintaining over time the established operational values ​​within specified limits, corresponding to the specified modes and conditions of use, maintenance, repairs, storage and transportation.

Reliability during operation depends on a number of factors: the nature and volume of work performed by the machine; natural and climatic conditions; adopted system of technical maintenance and repair of equipment; quality and availability of regulatory and technical documentation and means of maintenance, storage and transportation of machines; qualifications of service personnel.

Reliability is a complex property that includes, depending on the purpose of the object or its operating conditions, a number of simple properties:

1. Reliability - the property of an object to continuously maintain operability for some operating time or for some time.

2. Durability - the property of an object to maintain operability until a limit state occurs with an established system of maintenance and repairs.

3. Maintainability - a property of an object, which consists in its adaptability to preventing and detecting the causes of failures, maintaining and restoring operability through repairs and maintenance.

4. Storability - the property of an object to continuously maintain the required performance indicators during (and after) storage and transportation.

Depending on the object, reliability can be determined by all of the listed properties or some of them. For example, the reliability of a gear wheel and bearings is determined by their durability, and the reliability of a machine is determined by durability, reliability and maintainability

A car is a complex system consisting of thousands of parts with varying manufacturing and operational tolerances. Work is carried out under different conditions, so the service life of objects of the same type is different - depending on operating conditions, operating modes and the quality of the elements. Therefore, each unit must be sent for repairs according to its actual condition.

During an individual examination (monitoring, diagnosing, forecasting), the True technical condition of each unit is established. Here the influence of the whole variety of working conditions, operator qualifications and other factors on which the technical condition of the object depends can be taken into account.

The lack of special monitoring and diagnostic equipment makes it difficult to detect many faults. Old (mostly subjective) methods can only identify significant and obvious failures and deviations. The cost of checking major systems using these methods is approximately 70-75% higher than using modern diagnostic methods.

Technical diagnostic method - a set of technological and organizational rules for performing technical diagnostic operations.

Diagnostics (from the Greek diagnostikós - able to recognize) is a branch of knowledge that studies the technical condition of diagnostic objects (machines, mechanisms, equipment, structures and other technical objects) and the manifestation of technical conditions, developing methods for their determination, with the help of which a conclusion is given (a diagnosis is made) , as well as principles of construction and organization of use of diagnostic systems. When the objects of diagnosis are objects of a technical nature, we speak of technical diagnostics.

Diagnostics is a set of methods and tools for determining the main indicators of the technical condition of individual mechanisms and the machine as a whole without disassembling them or with partial disassembly.

The result of diagnosis is diagnosis - conclusion on the technical condition of the object, indicating, if necessary, the location, type and cause of the defect.

Reliability of diagnosis– the probability that during diagnostics the technical condition in which the diagnostic object is actually located is determined.

Technical condition- a set of properties of an object subject to change during production or operation, characterized at a certain point in time by signs and state parameters established by the technical documentation for this object.

State parameter- a physical quantity that characterizes the performance or serviceability of the diagnostic object and changes during operation.

Diagnostic operation - part of the diagnostic process, the implementation of which allows one or more diagnostic parameters of an object to be determined.

Diagnostic technology - a set of methods, parameters and diagnostic operations performed systematically and consistently in accordance with technological documentation to obtain the final diagnosis.

In Fig. Figure 1 shows the structure of technical diagnostics. It is characterized by two interpenetrating and interconnected directions: the theory of recognition and the theory of control ability. Recognition theory contains sections related to the construction of recognition algorithms, decision rules and diagnostic models. The theory of controllability includes the development of tools and methods for obtaining diagnostic information, automated control and troubleshooting. Technical diagnostics should be considered as a section of the general theory of reliability.

Diagnosis includes three main stages:

· obtaining information about the technical condition of the diagnostic object;

· processing and analysis of received information;

· making a diagnosis and making a decision.

The first stage is to determine the parameters of the object’s condition, establish qualitative characteristics of the condition and obtain data on operating time; the second - in processing and comparing the obtained values ​​of state parameters with nominal, permissible and limit values, as well as using the obtained data to predict the residual life; the third is in analyzing the forecasting results and establishing the volume and timing of maintenance and repair of machine components.

Diagnosis object- the product and its components subject to diagnostics.

The following objects are considered in technical diagnostics.

Element- the simplest component of a product in this consideration, in reliability problems can consist of many parts.

Product- a unit of product for a specific purpose, considered during the periods of design, production, testing and operation.

System- a set of jointly acting elements designed to independently perform specified functions.

The concepts of element, product and system are transformed depending on the task at hand. For example, when establishing its own reliability, a machine is considered as a system consisting of individual elements - mechanisms, parts, etc., and when studying the reliability of a production line - as an element.

Object structure - a conventional diagram of its structure, formed by the sequential division of an object into structural elements (components, assembly units, etc.).

When diagnosing, they distinguish work impacts, arriving at the facility during its operation, and test influences, which are supplied to the facility only for diagnostic purposes. Diagnostics, in which only working influences are applied to the object, is called functional, and diagnostics, in which test influences are applied to the object, - test technical diagnostics.

A set of means, performers and diagnostic objects, prepared for checking state parameters or carrying it out according to the rules established by the relevant documentation, is called technical diagnostic system.

Diagnostics allows you to: reduce machine downtime due to technical faults by preventing failures by timely adjustment, replacement or repair of individual mechanisms and assemblies; eliminate unnecessary disassembly of individual mechanisms and assemblies and reduce the wear rate of parts; correctly establish the type and scope of repairs and reduce the labor intensity of ongoing repairs by reducing disassembly, assembly and repair work; make fuller use of the resources of individual units and the machine as a whole, and consequently reduce the total number of repairs and the consumption of spare parts.

Experience in implementing diagnostics shows that the time between repairs increases by 1.5...2 times, the number of failures and malfunctions decreases by 2...2.5 times, and repair and maintenance costs are reduced by 25...30%.

In addition, the maintenance system for a fixed resource (the average system) does not provide high reliability and minimal costs. This system is gradually dying out; a new and more economical method of maintenance and repair based on actual technical condition (diagnostic system) is being increasingly introduced. This makes it possible to more fully utilize the between-repair life of machines, eliminate unreasonable disassembly of mechanisms, reduce downtime due to technical faults, and reduce the labor intensity of maintenance and repair. Condition-based operation can bring benefits equivalent to the cost of 30% of the total fleet.

In some cases, it is advisable to use combined (mixed) diagnostics - representing a set of regulated technical diagnostics and diagnostics based on technical condition.

Diagnostic and combined systems require new research methods and a different mathematical apparatus. The basis should be a theory of reliability. It is necessary to study more deeply and take into account changes in the physical patterns of failure, wear and aging of parts in mechanical systems. An important role in improving the reliability management of rolling stock belongs to the development and implementation of methods for predicting the technical condition of vehicle units.

Goals and objectives of technical diagnostics. Relationship between diagnostics and reliability

The purpose of technical diagnostics is to increase the reliability and service life of technical systems. Measures to maintain the reliability of machines are aimed at reducing the rate of change in state parameters (mainly the wear rate) of their components and preventing failures. As is known, the most important indicator of reliability is the absence of failures during the operation (operation) of a technical system.

Technical diagnostics, thanks to the early detection of defects and malfunctions, makes it possible to eliminate failures during the maintenance process, which increases the reliability and efficiency of operation.

THEORETICAL BASIS

TECHNICAL DIAGNOSIS OF OBJECTS

general characteristics

Technical diagnostics of objects

Basic concepts and definitions of technical diagnostics

The basic concepts and definitions used correspond to GOST 20911-89 (Technical diagnostics. Terms and definitions).

Technical diagnostics- this is a determination of the technical condition of an object, the result of which is a conclusion about the technical condition of the object, indicating, if necessary, the location, type and cause of failure. The term used in the literature “ technical condition monitoring” characterizes the definition type technical condition (serviceability, malfunction, operability, inoperability) of the object. In accordance with this, technical diagnostics, which is the process of determining the technical condition, can be either a complete independent process with indicators of its serviceability or performance not established in advance, or part of the process of predicting the technical condition of an object. Since monitoring and predicting the technical condition of an object requires knowledge of its actual technical condition, these processes always contain technical diagnostics.

It should be noted that the term “control” implies many activities, including organizational and technical ones, for example, technical control at an enterprise. Therefore, the concept of “monitoring the technical condition” of an object is often replaced by the concept of “technical diagnostics”. The final stage of diagnosis is obtaining technical diagnosis- diagnostic result.

When diagnosing, one should distinguish between working influences that are applied to the object during its operation, and test influences that are applied to the object only for diagnostics. In accordance with this, they distinguish working And test technical diagnostics. Working technical diagnostics are carried out during the operation of the object, which receives only working influences. Test technical diagnostics are carried out only under test influences.

The combination of diagnostic tools and objects and, if necessary, performers forms a technical diagnostic system (TDS). The components of the STD are:

· technical diagnostic object (TD) - a product or its components, the technical condition of which is subject to determination;

· technical diagnostic tool (SDT) - a set of measuring instruments, switching devices and interfaces with the DTD.

The technical diagnostic system operates in accordance with the technical diagnostic algorithm, which is a set of instructions for carrying out work. The algorithm establishes the composition and procedure for conducting the so-called basic checks objects and rules for analyzing their results.

An elementary test is determined by the working or test impact arriving or applied to the object, as well as the composition of the signs (parameters) that form the object’s response to the corresponding impact. The specific parameter values ​​obtained during diagnosis are the results of elementary checks or the values ​​of the object's responses.

From the point of view of the general theory of management and control, the operational diagnostic system is a control system, and the test diagnostic system can be considered as a control system in which control is carried out in accordance with the diagnostic algorithm.