Test Objectives of Control SystemsD

Test Objectives of Control SystemsDuring the evolution of a control system, from initial design to end use, different types of tests are carried out for different purposes. The test method, variables to be measured , test equipment , and data-reduction techniques should be selected with the overall test objectives in mind.This section discusses the testing requirements of different phases of control system development and application. These phases include design testing, system performance testing, production-acceptance testing, operational-check-out testing, and maintenance and trouble-shooting testing.That general objectives and criteria for each phase of testing are presented. In some cases, these are the same, while in other cases they are widely different.Desgin TestingDesign tests are carried out in conjunction with theoretical analysis and are usually performed under laboratory or pilot-plant conditions. The primary purpose of these tests is to obtain data for use in developing the initial analytical design and in refining the design. Gathering data to support the design involves establishing the transfer functions of the system to be controlled and/or the control elements to be used in the system. These data are necessary to perform the theoretical design.A second purpose is to provide a rough evaluation of the design to check validity of data and assumptions and to obtain more detailed information to indicate the direction to follow in further refinement of the design.For both purposes the tests must provide enough information to define the tested components so that they may be described in mathematical form for use in the analytical design.System Performance TestingSystem performance tests are usually conducted to completely check that system operation is within the specifications under required conditions of loads input signals, and environment. During this phase of testing, the system usually operates in its normal condition. i.e., closed loop. The test methods should be selected to make the important changes in operation readily apparent.Production-Acceptance TestingIn production- acceptance testing, the principal purpose is to check the operation of a manufactured system as a whole. The design is assumed to be finalized ,and the performance is established. For production testing, a valid set of performance data is ordinarily available for use as a reference to compare with test data for a production unit. Production tests for control systems and components range from tests which provide a simple visual check of the response to completely instrumented tests. The choice of tests is determined by sensitivity of system performance to manufacturing tolerances ,complexity of the system ,economy ,available facilities ,and ,last but not least ,customer requirements.