The design process of control system

发布于:2021-06-11 02:50:16

The design process of control system The skills needed for good design entail experience, intuition, and esthetic sensibility First you need a physical appreciation of the problem by determining the physical quantity or quantities that must be controlled, and the level of performance required. Obtaining a clear statement of the performance requirements is usually more difficult than you might think.Being unaware of implicit performance requirements, you might be tempted to adopt a nonstandard and seemingly innovative design approach leading to a control system that fails to meet these requirements. Striking the right balance between simplicity and verisimilitude is often a matter of insight and experience. Consider, for example, the problem of controlling the motion of an aircraft so that it proceeds from a given starting point to a specified destination subject to a variety of constraints such as permissible trajectories, available fuel, safety, Nowadays extensive software is available to assist in performing the calculations, so this step is rarely burdensome. Multiple objective and hidden constraints To be cost effective Number of state variables Disparate time scales Uncertain dynamics Your confidence in the model is not high enough to entrust to a brute-force mathematical optimization Failure to provide insight control system design considerations Safety Comply with environmental regulations Product specifications Operational constraints Some of the process inputs are specified as manipulated variables, while the other inputs are considered to be disturbance variables, specified by the external environment. Selection of controlled variables Select variables that are not self-regulating. Choose output variables that may exceed equipment and operating constraints Select output variables that are a direct measure of product quality or that strongly affect it Choose output variables that seriously interact with other controlled variables. Choose output variables that have favorable dynamic and static characteristics Selection of manipulated variables Choose inputs that rapidly affect the controlled variables The manipulated variables should affect the controlled variables directly rather than indirectly Compliance with this guideline Avoid recycling of disturbances Selection of measured variables Reliable, accurate measurements are essential for goog control Select measurement points that have an adequate degree of sensitivity

Select measurement points that minimize time delays and time constants