Monitoring and control systems · 监控与控制系统
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| preset value/ˈpriːset ˈvæljuː/ | 预设值 | yù shè zhí |
| actuator/ˈæktʃuːeɪtə/ | 执行器 | zhí xíng qì |
| monitoring/ˈmɒnɪtərɪŋ/ | 监控 | jiān kòng |
| sensors/ˈsensəz/ | 传感器 | chuán gǎn qì |
| control system/kənˈtrəʊl ˈsɪstəm/ | 控制系统 | kòng zhì xì tǒng |
| feedback/ˈfiːdbæk/ | 反馈 | fǎn kuì |
| thermistor/ˈθɜːmɪstə/ | 热敏电阻 | rè mǐn diàn zǔ |
| ADC/ˌeɪ diː ˈsiː/ | 模数转换器 | mó shù zhuǎn huàn qì |
| feedback loop/ˈfiːdbæk luːp/ | 反馈回路 | fǎn kuì huí lù |
The teacher who was tired of being interrupted
- In 1883 Warren Johnson, a college teacher in Wisconsin, was fed up with the janitor walking into his classroom to check the heating.
- He built a device with a strip of two metals that bent as the room warmed and cooled. At a set temperature it closed a circuit and rang a bell in the boiler room.
- A sensor, a preset value 预设值, a signal to someone who acts, and a room that is measured again afterwards: the first automatic control loop in a building.
- Today the loop is a processor and an actuator 执行器 instead of a janitor, but the parts are the same.
厌倦了被打扰的老师
- 1883 年,威斯康星州的大学教师 Warren Johnson 受够了校工走进他的教室检查暖气。
- 他造了一个装置,里面一条由两种金属组成的薄片随房间冷热而弯曲。在设定的温度下它接通电路,让锅炉房里的铃响起来。
- 一个传感器、一个预设值(preset value)、一个发给某个会去行动的人的信号,以及一间事后被再次测量的房间:建筑里第一个自动控制回路。
- 今天,这个回路里换成了处理器和执行器(actuator),不再是校工,但各个部分是一样的。
Monitoring and control
- Both kinds of system read sensors 传感器. The difference is what happens next.
- A monitoring 监控 system collects, records or displays the readings and takes no action, though it may raise a warning: a weather station, a patient monitor that beeps.
- A control system 控制系统 compares each reading with a preset value and, if it is outside the range, sends signals to actuators that change the physical process: a thermostat switching a boiler.
Monitoring reports; control acts and then measures again
监控与控制
- 两种系统都读取传感器(sensors)。区别在于接下来发生什么。
- 监控(monitoring)系统收集、记录或显示读数,不采取行动,不过可能发出警告:气象站、会响的病人监护仪。
- 控制系统(control system)把每个读数与一个预设值比较,如果超出范围,就向改变物理过程的执行器发送信号:切换锅炉的温控器。
监控报告;控制行动,然后再次测量
The key difference between a monitoring system and a control system is that a control system: · 一个监控系统和一个控制系统之间的关键区别是一个控制系统:
Both read sensors, but a control system uses the data to act (via actuators), while monitoring only collects and reports. · 两者都读传感器,但一个控制系统用数据来行动(通过执行器),而监控只收集和报告。
A pure monitoring system takes action through actuators to change its environment. · 一个纯监控系统通过执行器采取行动来改变它的环境。
Monitoring only collects and reports data — it does not act. Acting through actuators is what makes it a control system. · 监控只收集和报告数据——它不行动。通过执行器行动才使它成为一个控制系统。
Worked example: the three-mark "describe the differences"
- A monitoring system only measures, records or displays the readings, and at most raises a warning.
- A control system compares each reading with a preset value and, if it is outside the range, sends signals to actuators that change the process.
- The change is then measured again, so a control system contains feedback 反馈 and a monitoring system does not.
- Three points, three marks. The test for any system is the second point: does it act on the reading?
例题:三分的"描述不同"
- 监控系统只测量、记录或显示读数,最多发出一个警告。
- 控制系统把每个读数与预设值比较,如果超出范围,就向改变过程的执行器发送信号。
- 然后这个改变被再次测量,所以控制系统含有反馈(feedback),而监控系统没有。
- 三点,三分。判断任何系统的标准是第二点:它是否根据读数行动?
A control system compares each sensor reading with a ____ value and acts only if the reading is outside the range. · 控制系统把每个传感器读数与一个 ____ 值比较,只有读数超出范围时才行动。
The comparison with a stored, preset value is the mark that separates a control system from a device that merely reacts. · 与存储的预设值进行比较,是把控制系统和只会做出反应的设备区分开来的那一分。
Sensors
- A sensor turns a physical quantity into an electrical signal: temperature (a thermistor 热敏电阻 or thermocouple), pressure (a strain gauge), infra-red, sound, light, moisture.
- Most sensor signals are analogue, so an ADC 模数转换器 (analogue-to-digital converter) turns them into binary before the processor can compare them with anything.
- Name the sensor for the quantity: a "temperature sensor" is a fair answer, "thermistor" is a better one.
A thermistor: its resistance changes with temperature
传感器
- 传感器把一个物理量转成电信号:温度(热敏电阻,thermistor,或热电偶)、压力(应变片)、红外、声音、光、湿度。
- 大多数传感器信号是模拟的,所以 ADC(analogue-to-digital converter,模数转换器)先把它们转成二进制,处理器才能拿它们去比较。
- 为这个量说出传感器的名字:"温度传感器"是合格的答案,"热敏电阻"是更好的答案。
热敏电阻:它的电阻随温度变化
A sensor: · 一个传感器:
A sensor measures the world and outputs a signal. An actuator does the reverse — it turns a signal into an action. · 一个传感器测量世界并输出一个信号。一个执行器做相反的事——它把一个信号变成一个动作。
Actuators
- An actuator does the reverse of a sensor: it turns a signal from the processor into a physical action.
- Motors open doors and valves, heaters and coolers change a temperature, pumps move water, a buzzer or lamp warns a person.
- The processor's output is digital; where the actuator needs a varying signal, a DAC converts it first.
A motor: an actuator that turns a signal into movement
执行器
- 执行器做的是传感器的反向工作:把处理器的信号变成一个物理动作。
- 电机打开门和阀门,加热器和冷却器改变温度,泵移动水,蜂鸣器或灯提醒人。
- 处理器的输出是数字的;执行器需要连续变化的信号时,先由 DAC 转换。
电机:把信号变成运动的执行器
Match each device to whether it is a sensor (input) or an actuator (output). · 把每个设备与它是一个传感器(输入)还是一个执行器(输出)配对。
A sensor turns a physical quantity into a signal; an actuator turns a signal into a physical action. · 一个传感器把一个物理量变成一个信号;一个执行器把一个信号变成一个物理动作。
Which is an actuator? · 哪个是一个执行器?
An actuator carries out an action (motor, valve, heater, buzzer). The others are sensors/inputs. · 一个执行器执行一个动作(电机、阀门、加热器、蜂鸣器)。其他的是传感器/输入。
The control loop
- The sensor measures. The ADC converts the reading to digital. The processor compares it with the preset value.
- If the reading is outside the range, the processor sends a signal to an actuator, which changes the process.
- The sensor measures again, and the loop repeats. That repeated measuring after each action is the feedback loop 反馈回路.
控制回路
- 传感器测量。ADC 把读数转成数字。处理器把它与预设值比较。
- 如果读数超出范围,处理器向一个执行器发送信号,执行器改变过程。
- 传感器再次测量,回路重复。每次行动之后的重复测量就是反馈回路(feedback loop)。
The control feedback loop · 控制反馈回路
Tap round the loop a thermostat or autopilot repeats. A control system doesn't just read the world — it acts, then re-measures, correcting itself again and again. · 点击绕一个恒温器或自动驾驶仪重复的回路。一个控制系统不只是读取世界——它行动,然后重新测量,一次又一次地自我纠正。
Put the stages of one pass round a control loop in order. · 把控制回路一轮的各阶段按顺序排列。
Measure, convert, compare, act, measure again. The last step is what makes it feedback. · 测量、转换、比较、行动、再次测量。最后一步让它成为反馈。
Worked example: the automatic door
- Describe how a system opens a door when a person is within 2 metres and closes it when nobody is.
- An infra-red or ultrasonic sensor measures the distance to anything in front of the door. The ADC converts the analogue reading and sends it to the processor.
- The processor compares the distance with the preset 2 metres. If it is less, it sends a signal to the actuator, a motor, to open the door.
- The sensor keeps measuring. When no reading below 2 metres arrives, the processor signals the motor to close the door. The repeated measuring is the feedback.
例题:自动门
- 描述一个系统怎样在有人进入 2 米以内时开门、没有人时关门。
- 一个红外或超声传感器测量门前任何物体的距离。ADC 转换模拟读数并送给处理器。
- 处理器把距离与预设的 2 米比较。如果更小,它向执行器——一台电机——发送信号开门。
- 传感器持续测量。当不再收到低于 2 米的读数时,处理器给电机信号关门。重复测量就是反馈。
Which of these belong in the automatic door system? Select all · 所有 that apply. · 以下哪些属于自动门系统?选出所有适用的。
Sensor, converter, comparison value and actuator are the working parts. A printer would be monitoring bolted on; it plays no part in opening the door. · 传感器、转换器、比较值和执行器是工作部件。打印机只是附加的监控;它在开门这件事里不起作用。
Worked example: a greenhouse
- Keep a greenhouse between 20 °C and 26 °C. A thermistor reads the temperature; the ADC digitises it; the processor compares it with the two preset limits.
- Below 20 °C: a signal to the heater actuator switches it on. Above 26 °C: a signal to the motor opens the vent and switches the heater off.
- Inside the range: no action, but the reading is still taken. Then the loop repeats.
- Every control-system answer has these five parts: sensor, ADC, comparison with a preset, actuator, and measuring again.
例题:温室
- 让温室保持在 20 °C 到 26 °C 之间。热敏电阻读取温度;ADC 把它数字化;处理器把它与两个预设上下限比较。
- 低于 20 °C:向加热器执行器发送信号,把它打开。高于 26 °C:向电机发送信号打开通风口,并关掉加热器。
- 在范围内:不采取行动,但读数仍然要取。然后回路重复。
- 每个控制系统的答案都有这五个部分:传感器、ADC、与预设值比较、执行器、再次测量。
Why feedback matters
- Without feedback the system cannot tell whether its action worked, so it cannot correct itself or know when to stop. A heater with no temperature feedback heats forever.
- Feedback also lets the system respond to the world changing on its own: a door opened by hand, a cloud over the greenhouse.
- A monitoring system has no feedback because it changes nothing. It can only report or warn.
为什么反馈重要
- 没有反馈,系统无法知道自己的行动是否起效,所以无法自我纠正,也不知道何时停止。没有温度反馈的加热器会一直加热。
- 反馈还让系统能应对世界自己发生的变化:被人手动打开的门、飘到温室上方的云。
- 监控系统没有反馈,因为它什么也不改变。它只能报告或警告。
{/callout}
Why is feedback essential in a control system? · 为什么反馈在一个控制系统中是必不可少的?
Feedback closes the loop: the actuator changes the environment, the sensors re-measure it, and the system adjusts — e.g. a thermostat stops heating once the target is reached. · 反馈闭合回路:执行器改变环境,传感器重新测量它,系统调整——例如一个恒温器一旦达到目标就停止加热。
Match each system to its type. · 把每个系统与它的类型配对。
Raising an alarm is still reporting. Only a system that changes the physical process through an actuator is control. · 发出警报仍然是报告。只有通过执行器改变物理过程的系统才是控制。
Marks that slip away
- A monitoring system does not use actuators. If your answer has the weather station switching something on, it has become a control system.
- Sensor signals are analogue. Say the ADC converts them before the processor compares.
- The comparison is with a preset value. "The processor decides" is not a mark; "compares the reading with the stored 2 metres" is.
- Say that the loop repeats. The feedback point is the one most often left out.
容易丢掉的分
- 监控系统不使用执行器。如果你的答案里气象站打开了什么东西,它就变成了控制系统。
- 传感器信号是模拟的。要说 ADC 在处理器比较之前把它们转换。
- 比较的对象是预设值。"处理器做决定"不是一分;"把读数与存储的 2 米比较"才是。
- 要说回路重复。反馈这一点是最常被漏掉的。
You've got it
- monitoring = read sensors, record or display, at most warn; control = compare with a preset value, act through actuators, measure again
- a sensor turns a physical quantity into a signal, through an ADC; an actuator turns a signal into an action
- the loop: sensor → ADC → compare → actuator → measure again; the repeat is feedback
- describe any control system with those five parts, in that order
你掌握了
- 监控 = 读传感器、记录或显示、最多警告;控制 = 与预设值比较、通过执行器行动、再次测量
- 传感器通过 ADC 把物理量变成信号;执行器把信号变成动作
- 回路:传感器 → ADC → 比较 → 执行器 → 再次测量;重复就是反馈
- 用这五个部分、按这个顺序描述任何控制系统