闭环控制中英文对照.doc

英文原文Closed Loop ControlMany real-time embedded systems make control decisions. These decisions are usually made by software and based on feedback from the hardware under its control (termed the plant). Such feedback commonly takes the form of an analog sensor that can be read via an A/D converter. A sample from the sensor may represent position, voltage, temperature, or any other appropriate parameter. Each sample provides the software with additional information upon which to base its control decisions.Basics of Closed-Loop ControlEstablished based on the feedback control system theory. The so-called feedback principle, in accordance with changes in the information system output control, that is, by comparing the system behavior (output) and the deviation between the expected behavior, and the elimination of bias in order to achieve the desired system performance. In the feedback control system, there was not only the signal from the input to output prior to the pathway, also contain input from the output to the signal feedback path, the two form a closed loop. Therefore, the feedback control system, also known as closed loop control system. Feedback control is the main form of control. Most of the feedback control system control system. In engineering often to run the expectations manipulation to output and consistent feedback control system, known as automatic adjustment system, to be used to accurately follow or replicate a process known as feedback control system or servo servo system . Feedback control system by the controller, the controlled object and the feedback path formed. More links, for subtracting the input and output, error signal is given. This link may be in specific systems, together with the controller, referred to as regulators. With temperature control, for example, the controlled object for the stove; output variables for the actual oven temperature; input variables for a given constant temperature, usually expressed with the voltage. Temperature measurement using thermocouples, on behalf of the thermal emf and the furnace temperature for a given voltage compared to the difference between the voltage through the power amplified to drive the corresponding actuator control. Compared with open loop control system, closed-loop control has a number of advantages. In the feedback control system, for whatever reason (external disturbances or changes within the system), as long as the amount of deviation from the specified value to be controlled, it will generate the appropriate control action to eliminate bias. Therefore, it can inhibit the ability of interference, not sensitive to the device characteristics and can improve the systems response. However, the introduction of feedback loops to increase the complexity of the system, but choose not to then the gain will cause system instability. To improve the control precision can be measured in the disturbance variables, they often also used by disturbance of the control (ie, feedforward control) as a supplement to constitute a feedback control complex control systems.A Closed-Loop system utilizes feedback to measure the actual system operating parameter being controlled such as temperature, pressure, flow, level, or speed. This feedback signal is sent back to the controller where it is compared with the desired system setpoint. The controller develops an error signal that initiates corrective action and drives thefinal output device to the desired value. In the DC Motor Drive illustrated above, the tachometer provides a feedback voltage which is proportional to the actual motor speed. Closed-Loop Systems have the following features：1. A Reference or Set Point that establishes the desired operating point around which the system controls.2.The process variable Feedback signal that “tells” the controller at what point the system is actually operating.3.A Controller which compares the system Reference with the system Feedback and generates an Error signal that represents the difference between the desired operating point and the actual system operating value.4.A Final Control Element or mechanism which responds to the system Error to bring the system into balance.This may be a pneumatically controlled valve, an electronic positioner, a positioning motor, an SCR or transistor power inverter, a heating element, or other control device.5.System Tuning Elements which modify the control operation by introducing mathematical constants that tailor the control to the specific application, provide system stabilization, and adjust system response time. In process control systems these tuning elements are: Proportional, Integral, and Derivative (PID) functions. In electrical systems, such a generator voltage regulators and motor drives, typical tuning adjustments include:(1).Gain, the amplification factor of the controller error amplifier, which affects both system stability and response time;(2).Stability which pr。