比例积分微分控制器外文翻译(编辑修改稿)

比例积分微分控制器外文翻译(编辑修改稿)内容摘要：

t setpoint changes. Changes in feed water temperature constitute a disturbance to the shower process. In theory, a controller can be used to control any process which has a measurable output (PV), a known ideal value for that output (SP) and an input to the process (MV) that 无 锡 职 业 技 术 学 院 外文翻译 3 will affect the relevant PV. Controllers are used in industry to regulate temperature, pressure, flow rate, chemical position, speed and practically every other variable for which a measurement exists. Automobile cruise control is an example of a process which utilizes automated control. Due to their long history, simplicity, well grounded theory and simple setup and maintenance requirements, PID controllers are the controllers of choice for many of these applications. While PID controllers are applicable to many control problems, they can perform poorly in some controllers, when used alone, can give poor performance when the PID loop gains must be reduced so that the control system does not overshoot, oscillate or hunt about the control setpoint value. The control system performance can be improved by bining the feedback (or closedloop) control of a PID controller with feedforward (or openloop) control. Knowledge about the system (such as the desired acceleration and inertia) can be fed forward and bined with the PID output to improve the overall system performance. The feedforward value alone can often provide the major portion of the controller output. The PID controller can then be used primarily to respond to whatever difference or error remains between the setpoint (SP) and the actual value of the process variable (PV). Since the feedforward output is not affected by the process feedback, it can never cause the control system to oscillate, thus improving the system response and stability. For example, in most motion control systems, in order to accelerate a mechanical load under control, more force or torque is required from the prime mover, motor, or actuator. If a velocity loop PID controller is being used to control the speed of the load and mand the force or torque being applied by the prime mover, then it is beneficial to take the instantaneous acceleration desired for the load, scale that value a。