# 控制系统

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The centrifugal governor is an early proportional control mechanism.

A **control system** manages, commands, directs, or regulates the behavior of other devices or systems using control loops. It can range from a single home heating controller using a thermostat controlling a domestic boiler to large Industrial control systems which are used for controlling processes or machines.

A control system manages, commands, directs, or regulates the behavior of other devices or systems using control loops. It can range from a single home heating controller using a thermostat controlling a domestic boiler to large Industrial control systems which are used for controlling processes or machines.

**控制系统**使用控制循环control loop来管理、命令、引导或调节其他设备或系统的行为。它的范围，从使用恒温器thermostat控制家用锅炉的简单家庭供暖控制器，到控制机器或工艺流程Process engineering的大型工业控制系统Industrial control system。

For continuously modulated control, a feedback controller is used to automatically control a process or operation. The control system compares the value or status of the process variable (PV) being controlled with the desired value or setpoint (SP), and applies the difference as a control signal to bring the process variable output of the plant to the same value as the setpoint.

For continuously modulated control, a feedback controller is used to automatically control a process or operation. The control system compares the value or status of the process variable (PV) being controlled with the desired value or setpoint (SP), and applies the difference as a control signal to bring the process variable output of the plant to the same value as the setpoint.

反馈控制器feedback controller用来自动控制过程或操作，达到持续调节控制的目的。控制系统将把受控制的工艺参数process variable的当前值或状态（PV），与期望值或设定值Setpoint（SP）进行比较，并将差值作为控制信号，使设施的工艺参数的输出值与设定值相同。

For sequential and combinational logic, software logic, such as in a programmable logic controller, is used.

For sequential and combinational logic, software logic, such as in a programmable logic controller, is used.

算法Algorithm，例如可编程逻辑控制器，用来实现顺序逻辑Sequential logic和组合逻辑combinational logic的控制

## 开环控制和闭环控制 Open loop and closed loop control

There are two common classes of control action: open loop and closed loop. In an open-loop control system, the control action from the controller is independent of the process variable. An example of this is a central heating boiler controlled only by a timer. The control action is the switching on or off of the boiler. The process variable is the building temperature. This controller operates the heating system for a constant time regardless of the temperature of the building.

There are two common classes of control action: open loop and closed loop. In an open-loop control system, the control action from the controller is independent of the process variable. An example of this is a central heating boiler controlled only by a timer. The control action is the switching on or off of the boiler. The process variable is the building temperature. This controller operates the heating system for a constant time regardless of the temperature of the building.

有两种常见的控制动作: 开环和闭环。在开环控制系统open-loop control system中，来自控制器的控制动作独立于工艺参数。这方面的一个例子是，一个中央供暖锅炉只由一个定时器控制。控制动作是开启或关闭锅炉，工艺参数是建筑物的温度。该控制器只依照一个固定时间，操作供暖系统，不管建筑物的温度如何。

In a closed-loop control system, the control action from the controller is dependent on the desired and actual process variable. In the case of the boiler analogy, this would utilise a thermostat to monitor the building temperature, and feed back a signal to ensure the controller output maintains the building temperature close to that set on the thermostat. A closed loop controller has a feedback loop which ensures the controller exerts a control action to control a process variable at the same value as the setpoint. For this reason, closed-loop controllers are also called feedback controllers.^{[1]}

In a closed-loop control system, the control action from the controller is dependent on the desired and actual process variable. In the case of the boiler analogy, this would utilise a thermostat to monitor the building temperature, and feed back a signal to ensure the controller output maintains the building temperature close to that set on the thermostat. A closed loop controller has a feedback loop which ensures the controller exerts a control action to control a process variable at the same value as the setpoint. For this reason, closed-loop controllers are also called feedback controllers.

在闭环控制系统closed-loop control system中，控制器的控制动作，取决于期望的和实际的工艺参数。以锅炉的情况类比，要用一个恒温器来监测建筑物的温度，并反馈一个信号，以确保控制器的输出，保持建筑物的温度接近恒温器设定的温度。一个闭环控制器，有一个反馈回路，它确保控制器能施加一个控制动作，来控制工艺参数的值与设定值相同。因此，闭环控制器也称为反馈控制器^{[2]}。

## 反馈控制系统Feedback control systems

Example of a single industrial control loop; showing continuously modulated control of process flow.

单一工业控制回路的例子，显示工艺流程的连续调节控制。

A basic feedback loop

一个基本的反馈回路

In the case of linear feedback systems, a control loop including sensors, control algorithms, and actuators is arranged in an attempt to regulate a variable at a setpoint (SP). An everyday example is the cruise control on a road vehicle; where external influences such as hills would cause speed changes, and the driver has the ability to alter the desired set speed. The PID algorithm in the controller restores the actual speed to the desired speed in the optimum way, with minimal delay or overshoot, by controlling the power output of the vehicle's engine.

In the case of linear feedback systems, a control loop including sensors, control algorithms, and actuators is arranged in an attempt to regulate a variable at a setpoint (SP). An everyday example is the cruise control on a road vehicle; where external influences such as hills would cause speed changes, and the driver has the ability to alter the desired set speed. The PID algorithm in the controller restores the actual speed to the desired speed in the optimum way, with minimal delay or overshoot, by controlling the power output of the vehicle's engine.

在线性反馈feedback系统的情况下，控制回路control loop包括传感器sensor、控制算法和执行器，其目的是把参数调节为设定值Setpoint。一个日常的例子是公路车辆上的巡航控制，这种情形，山坡之类的外部影响，会导致速度变化，而驾驶员有能力调整期望、设定速度。控制器中的比例积分微分算法PID algorithm]]通过控制汽车发动机的功率输出，以最小的延迟或过冲overshoot，将实际转速，恢复到期望转速。

Control systems that include some sensing of the results they are trying to achieve are making use of feedback and can adapt to varying circumstances to some extent. Open-loop control systems do not make use of feedback, and run only in pre-arranged ways.

Control systems that include some sensing of the results they are trying to achieve are making use of feedback and can adapt to varying circumstances to some extent. Open-loop control systems do not make use of feedback, and run only in pre-arranged ways.

各种控制系统，以及对一些它们试图实现的结果的感知功能，可利用反馈机制，并能在一定程度上适应不同的环境。开环控制系统Open-loop control systems不利用反馈机制，只以预先安排的方式运行。

## 逻辑控制Logic control

Logic control systems for industrial and commercial machinery were historically implemented by interconnected electrical relays and cam timers using ladder logic. Today, most such systems are constructed with microcontrollers or more specialized programmable logic controllers (PLCs). The notation of ladder logic is still in use as a programming method for PLCs.^{[3]}

Logic control systems for industrial and commercial machinery were historically implemented by interconnected electrical relays and cam timers using ladder logic. Today, most such systems are constructed with microcontrollers or more specialized programmable logic controllers (PLCs). The notation of ladder logic is still in use as a programming method for PLCs.

工业和商业机械的逻辑控制系统，过去是通过梯形逻辑ladder logic中间继电器和凸轮定时器cam timer来实现。今天，大多数这样的系统是由微控制器microcontroller或更专业的可编程逻辑控制器programmable logic controller(PLC)来实现。梯形逻辑的符号仍然被用作一种可编程控制器的编程方法^{[3]}。

Logic controllers may respond to switches and sensors, and can cause the machinery to start and stop various operations through the use of actuators. Logic controllers are used to sequence mechanical operations in many applications. Examples include elevators, washing machines and other systems with interrelated operations. An automatic sequential control system may trigger a series of mechanical actuators in the correct sequence to perform a task. For example, various electric and pneumatic transducers may fold and glue a cardboard box, fill it with product and then seal it in an automatic packaging machine.

Logic controllers may respond to switches and sensors, and can cause the machinery to start and stop various operations through the use of actuators. Logic controllers are used to sequence mechanical operations in many applications. Examples include elevators, washing machines and other systems with interrelated operations. An automatic sequential control system may trigger a series of mechanical actuators in the correct sequence to perform a task. For example, various electric and pneumatic transducers may fold and glue a cardboard box, fill it with product and then seal it in an automatic packaging machine.

逻辑控制器能对开关和传感器相应，并能通过使用执行器actuator，实现机械的启动和停止等各种操作。在许多应用中，逻辑控制器被用来安排各种机械操作的次序。例如电梯、洗衣机和其它系统的相关操作。自动顺序控制系统，可以按照正确的顺序，触发一系列机械执行器来执行任务。例如，各种电动和气动装置，可以折叠和粘合纸板箱，把产品装箱，然后用自动包装机密封包装。

PLC software can be written in many different ways – ladder diagrams, SFC (sequential function charts) or statement lists.^{[4]}

PLC software can be written in many different ways – ladder diagrams, SFC (sequential function charts) or statement lists.

可编程逻辑控制器（PLC）软件，可以用许多不同的方式编写——梯形图、顺序功能流程图sequential function charts或语句表statement lists^{[4]}。

## 开关控制On–off control

On–off control uses a feedback controller that switches abruptly between two states. A simple bi-metallic domestic thermostat can be described as an on-off controller. When the temperature in the room (PV) goes below the user setting (SP), the heater is switched on. Another example is a pressure switch on an air compressor. When the pressure (PV) drops below the setpoint (SP) the compressor is powered. Refrigerators and vacuum pumps contain similar mechanisms. Simple on–off control systems like these can be cheap and effective.

On–off control uses a feedback controller that switches abruptly between two states. A simple bi-metallic domestic thermostat can be described as an on-off controller. When the temperature in the room (PV) goes below the user setting (SP), the heater is switched on. Another example is a pressure switch on an air compressor. When the pressure (PV) drops below the setpoint (SP) the compressor is powered. Refrigerators and vacuum pumps contain similar mechanisms. Simple on–off control systems like these can be cheap and effective.

开关控制使用在两种状态之间突然切换的反馈控制器。一个简单的双金属家用恒温器thermostat可以描述为一个开关控制器。当室内温度(工艺参数当前值)低于用户设置(设定值)时，加热器就会打开。另一个例子是空气压缩机上的压力开关。当压力(工艺参数当前值)下降到设定点(设定值)以下时，压缩机启动。冰箱和真空泵也有类似的机理。像这样简单的开关控制系统可以是廉价和有效的。

## 线性控制Linear control

Linear control systems use negative feedback to produce a control signal to maintain the controlled PV at the desired SP. There are several types of linear control systems with different capabilities.

Linear control systems use negative feedback to produce a control signal to maintain the controlled PV at the desired SP. There are several types of linear control systems with different capabilities.

线性控制系统使用负反馈negative feedback 产生控制信号，让受控的工艺参数保持在需要的设置值。下面是几种线性控制系统，具有不同的功能。

### 比例控制Proportional control

Step responses for a second order system defined by the [[transfer function [math]\displaystyle{ H(s)=\frac{\omega^2_n}{s^2+2\zeta\omega_ns+\omega^2_n} }[/math], where [math]\displaystyle{ \zeta }[/math] is the damping ratio and [math]\displaystyle{ \omega_n }[/math] is the undamped natural frequency.]]

由传递函数transfer function[math]\displaystyle{ H(s)=\frac{\omega^2_n}{s^2+2\zeta\omega_ns+\omega^2_n} }[/math] 定义的二阶系统的阶跃响应，其中[math]\displaystyle{ \zeta }[/math] 是阻尼比，[math]\displaystyle{ \omega_n }[/math]是无阻尼自然频率undamped natural frequency

Proportional control is a type of linear feedback control system in which a correction is applied to the controlled variable which is proportional to the difference between the desired value (SP) and the measured value (PV). Two classic mechanical examples are the toilet bowl float proportioning valve and the fly-ball governor.

Proportional control is a type of linear feedback control system in which a correction is applied to the controlled variable which is proportional to the difference between the desired value (SP) and the measured value (PV). Two classic mechanical examples are the toilet bowl float proportioning valve and the fly-ball governor.

比例控制是一种线性反馈控制系统，其中，对被控变量进行修正，修正值与期望值(设定值)和实测值(工艺参数当前值)之间的差值成正比。两个经典的机械例子是马桶浮子比例阀float proportioning valve和飞球调速器fly-ball governor。

The proportional control system is more complex than an on–off control system, but simpler than a proportional-integral-derivative (PID) control system used, for instance, in an automobile cruise control. On–off control will work for systems that do not require high accuracy or responsiveness, but is not effective for rapid and timely corrections and responses. Proportional control overcomes this by modulating the manipulated variable (MV), such as a control valve, at a gain level which avoids instability, but applies correction as fast as practicable by applying the optimum quantity of proportional correction.

The proportional control system is more complex than an on–off control system, but simpler than a proportional-integral-derivative (PID) control system used, for instance, in an automobile cruise control. On–off control will work for systems that do not require high accuracy or responsiveness, but is not effective for rapid and timely corrections and responses. Proportional control overcomes this by modulating the manipulated variable (MV), such as a control valve, at a gain level which avoids instability, but applies correction as fast as practicable by applying the optimum quantity of proportional correction.

比例控制系统比开关控制系统更复杂，但比“比例-积分-微分”proportional-integral-derivative(PID)控制系统更简单，例如，汽车巡航控制cruise control。开关控制适用于不要求高准确度或高响应能力的系统，对快速的、及时的修正和响应，它无效。比例控制，通过调节控制变量（MV），如控制阀control valve，在避免不稳定性的增益水平上，通过应用比例校正的最佳量作为修正量，尽可能快地进行修正，从而克服了这一问题。

A drawback of proportional control is that it cannot eliminate the residual SP–PV error, as it requires an error to generate a proportional output. A PI controller can be used to overcome this. The PI controller uses a proportional term (P) to remove the gross error, and an integral term (I) to eliminate the residual offset error by integrating the error over time.

A drawback of proportional control is that it cannot eliminate the residual SP–PV error, as it requires an error to generate a proportional output. A PI controller can be used to overcome this. The PI controller uses a proportional term (P) to remove the gross error, and an integral term (I) to eliminate the residual offset error by integrating the error over time.

比例控制的一个缺点是，它不能消除剩余的“工艺参数当前值-设定值”误差（SP-PV误差），因为它需要一个误差来产生一个比例输出。一个比例积分控制器PI controller，可以用来解决这个问题。比例积分控制器采用比例项(P)消除粗差，积分项(I)通过对误差进行积分，消除残差。

In some systems there are practical limits to the range of the MV. For example, a heater has a limit to how much heat it can produce and a valve can open only so far. Adjustments to the gain simultaneously alter the range of error values over which the MV is between these limits. The width of this range, in units of the error variable and therefore of the PV, is called the *proportional band* (PB).

In some systems there are practical limits to the range of the MV. For example, a heater has a limit to how much heat it can produce and a valve can open only so far. Adjustments to the gain simultaneously alter the range of error values over which the MV is between these limits. The width of this range, in units of the error variable and therefore of the PV, is called the proportional band (PB).

在一些系统中，对于控制变量的范围，有实际的限制。例如，加热器能产生的热量是有限制的，阀门只能打开这么大。调整增益同时改变误差值的范围，控制变量只能在这个范围内。这个范围的宽度，以误差变量和工艺参数的现值为单位，被称为“比例带宽”(PB)。

#### Furnace example

When controlling the temperature of an industrial furnace, it is usually better to control the opening of the fuel valve *in proportion to* the current needs of the furnace. This helps avoid thermal shocks and applies heat more effectively.

When controlling the temperature of an industrial furnace, it is usually better to control the opening of the fuel valve in proportion to the current needs of the furnace. This helps avoid thermal shocks and applies heat more effectively.

#### 锅炉的例子

在控制工业锅炉industrial furnace的温度时，通常，根据炉子当前的需要，按比例控制燃料阀的开度，这样更好。这有助于避免热冲击，并更有效地利用热量。

At low gains, only a small corrective action is applied when errors are detected. The system may be safe and stable, but may be sluggish in response to changing conditions. Errors will remain uncorrected for relatively long periods of time and the system is overdamped. If the proportional gain is increased, such systems become more responsive and errors are dealt with more quickly. There is an optimal value for the gain setting when the overall system is said to be critically damped. Increases in loop gain beyond this point lead to oscillations in the PV and such a system is underdamped. Adjusting gain to achieve critically damped behavior is known as *tuning* the control system.

At low gains, only a small corrective action is applied when errors are detected. The system may be safe and stable, but may be sluggish in response to changing conditions. Errors will remain uncorrected for relatively long periods of time and the system is overdamped. If the proportional gain is increased, such systems become more responsive and errors are dealt with more quickly. There is an optimal value for the gain setting when the overall system is said to be critically damped. Increases in loop gain beyond this point lead to oscillations in the PV and such a system is underdamped. Adjusting gain to achieve critically damped behavior is known as tuning the control system.

在低增益情况下，当检测到错误时，只采用一个小的纠正措施。该系统可能是安全和稳定的，但对不断变化的情况，可能会反应迟缓。在相当长的一段时间内，错误仍然没有得到纠正，系统表现为过度阻滞overdamped。如果提高比例增益，这样的系统将会更快响应，更快处理错误。如果说整个系统处于临界阻尼critically damped时，增益设置有一个最佳值。提高环路增益，超过这一点时，会导致工艺参数当前值的振荡。这样的系统，阻尼不足underdamped。调节增益使之达到临界阻尼的行为，被称为控制系统的调试。

In the underdamped case, the furnace heats quickly. Once the setpoint is reached, stored heat within the heater sub-system and in the walls of the furnace will keep the measured temperature rising beyond what is required. After rising above the setpoint, the temperature falls back and eventually heat is applied again. Any delay in reheating the heater sub-system allows the furnace temperature to fall further below setpoint and the cycle repeats. The temperature oscillations that an underdamped furnace control system produces are undesirable.

In the underdamped case, the furnace heats quickly. Once the setpoint is reached, stored heat within the heater sub-system and in the walls of the furnace will keep the measured temperature rising beyond what is required. After rising above the setpoint, the temperature falls back and eventually heat is applied again. Any delay in reheating the heater sub-system allows the furnace temperature to fall further below setpoint and the cycle repeats. The temperature oscillations that an underdamped furnace control system produces are undesirable.

在阻尼不足的情况下，炉子加热很快。一旦达到设定值，存储在加热器子系统和炉壁中的热量，会使实测温度上升并超出所需的温度。当温度上升到设定值以上时，温度回落，最终再次加热。任何加热子系统再加热的延迟，都会使炉温进一步下降到设定值以下，循环重复。阻尼不足的炉子控制系统产生的温度振荡，是不可取的。

In a critically damped system, as the temperature approaches the setpoint, the heat input begins to be reduced, the rate of heating of the furnace has time to slow and the system avoids overshoot. Overshoot is also avoided in an overdamped system but an overdamped system is unnecessarily slow to initially reach setpoint respond to external changes to the system, e.g. opening the furnace door.

In a critically damped system, as the temperature approaches the setpoint, the heat input begins to be reduced, the rate of heating of the furnace has time to slow and the system avoids overshoot. Overshoot is also avoided in an overdamped system but an overdamped system is unnecessarily slow to initially reach setpoint respond to external changes to the system, e.g. opening the furnace door.

在临界阻尼系统中，当温度接近设定值时，热输入开始减少，加热的速率，有时间变慢，系统可避免给过冲。在过阻尼系统中，也可以避免过冲。但是过阻尼系统在快要到达设定值时，它会对系统的外部变化的反应，例如:打开炉门，会出现不必要的缓慢。

### PID control

### 比例积分微分（PID）控制

A block diagram of a PID controller

比例积分微分（PID）控制器的框图block diagram of a PID controller

Effects of varying PID parameters (K_{p},K_{i},K_{d}) on the step response of a system.

不同比例积分微分（PID）参数(K_{p},K_{i},K_{d})对系统阶跃响应的影响。

Pure proportional controllers must operate with residual error in the system. Though PI controllers eliminate this error they can still be sluggish or produce oscillations. The PID controller addresses these final shortcomings by introducing a derivative (D) action to retain stability while responsiveness is improved.

Pure proportional controllers must operate with residual error in the system. Though PI controllers eliminate this error they can still be sluggish or produce oscillations. The PID controller addresses these final shortcomings by introducing a derivative (D) action to retain stability while responsiveness is improved.

纯粹的比例控制器，必须在系统中处理剩余误差。虽然PI控制器消除了这个错误，但是它们仍然可能表现迟缓，或者产生振荡。比例积分微分（PID）控制器，通过引入一个微分derivative(D)动作，来解决这种最后的缺点，从而保持稳定性，同时提高响应速度。

#### Derivative action

The derivative is concerned with the rate-of-change of the error with time: If the measured variable approaches the setpoint rapidly, then the actuator is backed off early to allow it to coast to the required level; conversely, if the measured value begins to move rapidly away from the setpoint, extra effort is applied—in proportion to that rapidity to help move it back.

The derivative is concerned with the rate-of-change of the error with time: If the measured variable approaches the setpoint rapidly, then the actuator is backed off early to allow it to coast to the required level; conversely, if the measured value begins to move rapidly away from the setpoint, extra effort is applied—in proportion to that rapidity to help move it back.

#### 微分动作

导数与误差随时间的变化率有关: 如果实测的变量迅速接近设定值，那么执行器就会提前关机，让它滑行到所需的水平; 反之，如果实测值开始迅速远离设定值，执行器会额外努力——与该速度成比例，帮助它回移。

On control systems involving motion-control of a heavy item like a gun or camera on a moving vehicle, the derivative action of a well-tuned PID controller can allow it to reach and maintain a setpoint better than most skilled human operators. If derivative action is over-applied, it can, however, lead to oscillations.

On control systems involving motion-control of a heavy item like a gun or camera on a moving vehicle, the derivative action of a well-tuned PID controller can allow it to reach and maintain a setpoint better than most skilled human operators. If derivative action is over-applied, it can, however, lead to oscillations.

在控制系统中，涉及到一个重物的运动控制，如移动车辆上的枪或摄像机，一个调试良好的比例积分微分（PID）控制器的微分动作，可以使它达到和保持一个设定值，做得比最熟练的人类操作员更好。然而，如果微分动作被过度应用，它可以导致振荡。

#### Integral action

#### 积分动作

Change of response of second-order system to a step input for varying Ki values.

变Ki值的二阶系统对阶跃输入的响应的变化。

The integral term magnifies the effect of long-term steady-state errors, applying an ever-increasing effort until error is removed. In the example of the furnace above working at various temperatures, if the heat being applied does not bring the furnace up to setpoint, for whatever reason, integral action increasingly *moves* the proportional band relative to the setpoint until the PV error is reduced to zero and the setpoint is achieved.

The integral term magnifies the effect of long-term steady-state errors, applying an ever-increasing effort until error is removed. In the example of the furnace above working at various temperatures, if the heat being applied does not bring the furnace up to setpoint, for whatever reason, integral action increasingly moves the proportional band relative to the setpoint until the PV error is reduced to zero and the setpoint is achieved.

积分项放大了长期稳态误差的影响，它不断努力，直到误差被消除。以前文的不同温度下工作的炉子为例，如果施加的热量，没有使炉子达到设定值，不管出于什么原因，积分作用会越来越多地使比例带相对于设定值移动，直到它与工艺参数当前值（PV）的差值，减少到零，从而达到设定值。

#### Ramp up % per minute

### 每分钟斜升%

Some controllers include the option to limit the "ramp up % per minute". This option can be very helpful in stabilizing small boilers (3 MBTUH), especially during the summer, during light loads. A utility boiler "unit may be required to change load at a rate of as much as 5% per minute (IEA Coal Online - 2, 2007)".^{[5]}模板:Fv

Some controllers include the option to limit the "ramp up % per minute". This option can be very helpful in stabilizing small boilers (3 MBTUH), especially during the summer, during light loads. A utility boiler "unit may be required to change load at a rate of as much as 5% per minute (IEA Coal Online - 2, 2007)".

一些控制器包括限制“每分钟斜升%”的选项。这种选择，非常有助于稳定小锅炉(每小时300万英国热量单位) ，特别是在夏季，在负荷轻时。公共服务锅炉“可能需要以每分钟5%的速度改变负荷(IEA Coal Online-2,2007)”^{[6]}。

### Other techniques

### 其他技术

It is possible to filter the PV or error signal. Doing so can help reduce instability or oscillations by reducing the response of the system to undesirable frequencies. Many systems have a resonant frequency. By filtering out that frequency, stronger overall feedback can be applied before oscillation occurs, making the system more responsive without shaking itself apart.

It is possible to filter the PV or error signal. Doing so can help reduce instability or oscillations by reducing the response of the system to undesirable frequencies. Many systems have a resonant frequency. By filtering out that frequency, stronger overall feedback can be applied before oscillation occurs, making the system more responsive without shaking itself apart.

可以对工艺参数当前值或错误信号进行过滤filter (信号处理)。这样做可以减少系统对不希望的频率的响应，从而减少系统的不稳定性或振荡。许多系统都有一个共振频率resonant frequency。在振荡发生之前，通过过滤掉这个频率，可以用更强的总反馈，使系统在没有自身振荡的情况下，反应更快。

Feedback systems can be combined. In cascade control, one control loop applies control algorithms to a measured variable against a setpoint but then provides a varying setpoint to another control loop rather than affecting process variables directly. If a system has several different measured variables to be controlled, separate control systems will be present for each of them.

Feedback systems can be combined. In cascade control, one control loop applies control algorithms to a measured variable against a setpoint but then provides a varying setpoint to another control loop rather than affecting process variables directly. If a system has several different measured variables to be controlled, separate control systems will be present for each of them.

几个反馈系统，可以组合起来。在联级控制cascade control中，一个控制回路针对一个设定值的实测变量采用控制算法，然后，用另一个控制回路针对一个可变的设定值（过程变量），而不是（用第一个控制回路）直接影响过程变量。如果一个系统有几个不同的实测变量需要控制，每个变量都会有自己的子控制系统。

Control engineering in many applications produces control systems that are more complex than PID control. Examples of such fields applications fly-by-wire aircraft control systems, chemical plants, and oil refineries. Model predictive control systems are designed using specialized computer-aided-design software and empirical mathematical models of the system to be controlled.

Control engineering in many applications produces control systems that are more complex than PID control. Examples of such fields applications fly-by-wire aircraft control systems, chemical plants, and oil refineries. Model predictive control systems are designed using specialized computer-aided-design software and empirical mathematical models of the system to be controlled.

在许多实际应用中，用控制工程Control engineering设计制造的控制系统，与比例积分微分控制（PID）对比，更加复杂。这些领域应用的例子，包括电传飞机控制系统、化工厂和炼油厂。模块化预测控制Model predictive control系统，使用专门的计算机辅助设计computer-aided-design 软件和被控系统的经验数学模型，来进行设计。

## 模糊逻辑Fuzzy logic

Fuzzy logic is an attempt to apply the easy design of logic controllers to the control of complex continuously varying systems. Basically, a measurement in a fuzzy logic system can be partly true, that is if yes is 1 and no is 0, a fuzzy measurement can be between 0 and 1.

Fuzzy logic is an attempt to apply the easy design of logic controllers to the control of complex continuously varying systems. Basically, a measurement in a fuzzy logic system can be partly true, that is if yes is 1 and no is 0, a fuzzy measurement can be between 0 and 1.

模糊逻辑Fuzzy logic是将易于设计的逻辑控制器应用于复杂连续变化系统的一种尝试。基本上，模糊逻辑系统中的一项测量，有可能部分正确，即如果“是”是1，“否”是0，一项模糊测量，可以介于0和1之间。

The rules of the system are written in natural language and translated into fuzzy logic. For example, the design for a furnace would start with: "If the temperature is too high, reduce the fuel to the furnace. If the temperature is too low, increase the fuel to the furnace."

The rules of the system are written in natural language and translated into fuzzy logic. For example, the design for a furnace would start with: "If the temperature is too high, reduce the fuel to the furnace. If the temperature is too low, increase the fuel to the furnace."

系统的规则用自然语言编写，并转换成模糊逻辑。例如，对火炉的设计，这样开始: “如果温度太高，减少火炉的燃料。如果温度太低，就增加火炉的燃料。”

Measurements from the real world (such as the temperature of a furnace) are converted to values between 0 and 1 by seeing where they fall on a triangle. Usually, the tip of the triangle is the maximum possible value which translates to 1.

Measurements from the real world (such as the temperature of a furnace) are converted to values between 0 and 1 by seeing where they fall on a triangle. Usually, the tip of the triangle is the maximum possible value which translates to 1.

来自真实世界的测量值(比如火炉的温度)，看它们落在三角形上的位置，被转换为0到1之间的值。通常，三角形的顶端是最大可能值，也就是1。<！-- 请解释一下，想必需要两个输入传感器，才能形成一个三角形，一个刚好落在一条直角边上，而其余的传感器，落在其他维度的方向。-->

Fuzzy logic, then, modifies Boolean logic to be arithmetical. Usually the "not" operation is "output = 1 - input," the "and" operation is "output = input.1 multiplied by input.2," and "or" is "output = 1 - ((1 - input.1) multiplied by (1 - input.2))". This reduces to Boolean arithmetic if values are restricted to 0 and 1, instead of allowed to range in the unit interval [0,1].

Fuzzy logic, then, modifies Boolean logic to be arithmetical. Usually the "not" operation is "output = 1 - input," the "and" operation is "output = input.1 multiplied by input.2," and "or" is "output = 1 - ((1 - input.1) multiplied by (1 - input.2))". This reduces to Boolean arithmetic if values are restricted to 0 and 1, instead of allowed to range in the unit interval [0,1].

然后，模糊逻辑将布尔逻辑Boolean logic转变为算术运算。通常“否”操作是“输出= 1- 输入” ，“与”操作是“输出=‘输入.1’乘以‘输入.2’” ，“或”操作是“输出 = 1-(1- ‘输入.1’)乘以(1- ‘输入.2’)”。如果值被限制为0和1，而不是允许在单位区间unit interval[0,1]范围内，那么这就简化为布尔运算Boolean arithmetic。

The last step is to "defuzzify" an output. Basically, the fuzzy calculations make a value between zero and one. That number is used to select a value on a line whose slope and height converts the fuzzy value to a real-world output number. The number then controls real machinery.

The last step is to "defuzzify" an output. Basically, the fuzzy calculations make a value between zero and one. That number is used to select a value on a line whose slope and height converts the fuzzy value to a real-world output number. The number then controls real machinery.

最后一步，是“去模糊化”输出。基本上，模糊计算产生一个介于0和1之间的数字。该数字用于选定一条线上的值，它的斜率和高度，将模糊值转换为一个真实世界的输出数字。然后，这个数字，控制着真正的机器。

If the triangles are defined correctly and rules are right the result can be a good control system.

If the triangles are defined correctly and rules are right the result can be a good control system.

如果三角形定义正确，规则恰当，那么结果就会是一个好的控制系统。

When a robust fuzzy design is reduced into a single, quick calculation, it begins to resemble a conventional feedback loop solution and it might appear that the fuzzy design was unnecessary. However, the fuzzy logic paradigm may provide scalability for large control systems where conventional methods become unwieldy or costly to derive.

When a robust fuzzy design is reduced into a single, quick calculation, it begins to resemble a conventional feedback loop solution and it might appear that the fuzzy design was unnecessary. However, the fuzzy logic paradigm may provide scalability for large control systems where conventional methods become unwieldy or costly to derive.

一个鲁棒模糊设计被简化为一个单一的、快速的计算时，它会类似于一个传统的反馈回路的解决方案，它可能会让模糊设计显得不必要。然而，在大型控制系统中，模糊逻辑的范式，可以提供扩展性，而传统的方法，会变得很难扩展或代价高昂。

Fuzzy electronics is an electronic technology that uses fuzzy logic instead of the two-value logic more commonly used in digital electronics.

Fuzzy electronics is an electronic technology that uses fuzzy logic instead of the two-value logic more commonly used in digital electronics.

模糊电子电路Fuzzy electronics是一种电子技术，它使用模糊逻辑代替数字电子电路digital electronics中常用的二值逻辑。

## 物理实现Physical implementation

A DCS control room where plant information and controls are displayed on computer graphics screens. The operators are seated as they can view and control any part of the process from their screens, whilst retaining a plant overview.

一个集散控制系统（DCS）控制室，工厂信息和控制信息显示在计算机的图形屏幕上。操作员坐着，他们可以从屏幕上观察和控制过程的任何部分，同时观察着工厂的总体情况。

A control panel of a hydraulic heat press machine with dedicated software for that function

带有专门软件的液压热压机的控制面板

The range of implementation is from compact controllers often with dedicated software for a particular machine or device, to distributed control systems for industrial process control.

The range of implementation is from compact controllers often with dedicated software for a particular machine or device, to distributed control systems for industrial process control.

从带有专门控制软件的紧凑型控制器compact controller，用于特定的机器或设备，到集散式控制系统 用于工业过程控制，都在可实现的范围内。

Logic systems and feedback controllers are usually implemented with programmable logic controllers.

Logic systems and feedback controllers are usually implemented with programmable logic controllers.

逻辑系统和反馈控制器，通常用可编程逻辑控制器programmable logic controller来实现。

## 参见See also

## References

- ↑ "Feedback and control systems" - JJ Di Steffano, AR Stubberud, IJ Williams. Schaums outline series, McGraw-Hill 1967
- ↑ "Feedback and control systems" - JJ Di Steffano, AR Stubberud, IJ Williams. Schaums outline series, McGraw-Hill 1967
- ↑
^{3.0}^{3.1}Kuphaldt, Tony R. "Chapter 6 LADDER LOGIC".*Lessons In Electric Circuits -- Volume IV*. Archived from the original on 12 September 2010. Retrieved 22 September 2010. - ↑
^{4.0}^{4.1}Brady, Ian. "Programmable logic controllers - benefits and applications" (PDF).*PLCs*. Archived (PDF) from the original on 2 February 2014. Retrieved 5 December 2011. - ↑ "Energy Efficient Design of Auxiliary Systems in Fossil-Fuel Power Plants" (PDF). ABB. p. 262. Archived (PDF) from the original on 2014-08-05. Retrieved 2014-04-07.
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## External links

- SystemControl Create, simulate or HWIL control loops with Python. Includes Kalman filter, LQG control among others.

- Control System Toolbox for design and analysis of control systems.

- Control Systems Manufacturer Design and Manufacture of control systems.

- Python Control System (PyConSys) Create and simulate control loops with Python. AI for setting PID parameters.

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