6.1 · Automated systems
6.1 · 自动化系统
Automated systems
自动化系统
How sensors, a microprocessor and actuators work together to run a system automatically, and how to weigh the benefits and drawbacks of an automated system for a scenario the question gives you.
传感器、微处理器和执行器如何协同工作,让一个系统自动运行;以及在给定情境中使用自动化系统的优点与缺点。
Explainer · 6.1.1
讲解 · 6.1.1
An automated system has three parts
一个自动化系统有三个组成部分
An automated system uses hardware (sensors, a microprocessor and actuators) and software together to run a task on its own, without a person controlling it. A human may still watch over it. Three kinds of part do the work.
自动化系统是硬件和软件的结合,它自行运行某项任务,无需人来操控。人可能仍在旁边监看。有三类部件负责干活。
| Part | 部件 | What it does | 它的职责 |
|---|---|---|---|
| Sensor | 传感器 | an input device; it takes readings of a physical property (temperature, light, moisture, distance) from its surroundings and sends the readings to the microprocessor, constantly, not only when something changes | 一种输入设备;它测量周围环境的某个物理量(温度、光照、湿度、距离),并把读数持续不断地发送给微处理器,而不是只在有变化时才发 |
| Microprocessor | 微处理器 | the decision maker; it compares each reading with a stored value (the pre-set value) and, based on its program, decides whether an action is needed | 决策者;它把每个读数与一个存储的值(预设值)相比较,并根据自己的程序,判断是否需要采取动作 |
| Actuator | 执行器 | receives a signal from the microprocessor and produces a physical movement: it operates a motor, valve, pump, heater or brake; it does not display anything or send data back | 接收来自微处理器的信号,并产生一个物理动作:它驱动马达、阀门、泵、加热器或刹车;它不显示任何东西,也不回传数据 |
Keep the roles apart. The sensor only measures and reports. The microprocessor does the deciding. The actuator only moves things. A sensor does not decide; an actuator does not send data.
把三个角色分开。传感器只负责测量和上报。微处理器负责做决定。执行器只负责让东西动起来。传感器不做决定;执行器不发送数据。
Try it yourself
动手试试
A reading or an action?
是读数还是动作?
Tap each job to tag it as one a sensor does (takes a reading) or one an actuator does (carries out an action), then check.
点击每项工作,把它标记为传感器做的事(测量读数)还是执行器做的事(执行动作),然后检查。
Explainer · 6.1.1
讲解 · 6.1.1
How the three parts work together
三个部件如何协同工作
The parts form a loop that repeats for as long as the system is switched on.
这些部件构成一个回路,只要系统开着就一直重复。
| Step | 步骤 | What happens | 发生了什么 |
|---|---|---|---|
| 1 | 1 | the sensor takes a reading and sends it towards the microprocessor | 传感器测量一个读数,并把它发往微处理器 |
| 2 | 2 | if the reading is analogue, an ADC (analogue-to-digital converter) turns it into a digital value the microprocessor can use | 如果读数是模拟量,ADC(模数转换器)把它转换成微处理器能使用的数字值 |
| 3 | 3 | the microprocessor compares the reading with the pre-set value stored in its memory | 微处理器把读数与存储在其内存中的预设值相比较 |
| 4 | 4 | if the reading is outside the wanted range, the microprocessor signals an actuator to act (through a DAC if the actuator needs an analogue signal) | 如果读数超出所需范围,微处理器就向某个执行器发送信号(若执行器需要模拟信号,则经过 DAC) |
| 5 | 5 | the actuator carries out a physical action that changes the surroundings (heats, cools, opens, closes, moves) | 执行器执行一个物理动作,改变周围环境(加热、冷却、打开、关闭、移动) |
| 6 | 6 | the change affects the next reading the sensor takes, and the loop starts again: this is feedback | 这个变化会影响传感器下一次的读数,回路重新开始:这就是反馈 |
Feedback is when the output of the system changes the surroundings, which changes the next input the sensor reads, so the system keeps correcting itself.
反馈是指:系统的输出改变了周围环境,而这又改变了传感器读到的下一个输入,于是系统不断地自我修正。
Try it yourself
动手试试
Explore each part
逐一了解每个部分
Click each part of the loop to see exactly what it does.
点击回路中的每个部分,看看它究竟做什么。
Worked example · 6.1.1
范例 · 6.1.1
Chloe's tropical fish tank
Chloe 的热带鱼缸
Chloe keeps tropical fish that need the water held at 25 °C. An automated heater keeps it there. In an exam you would describe how the parts interact for this tank, not heating in general.
Chloe 养的热带鱼需要把水温保持在 25 °C。一个自动加热器让水温维持在那里。在考试中,你要描述这个鱼缸里各部分如何相互作用,而不是泛泛地讲加热。
| Part in this system | 该系统中的部件 | Its job here | 它在这里的工作 |
|---|---|---|---|
| Temperature sensor | 温度传感器 | sits in the water and sends the current water temperature to the microprocessor several times a second | 置于水中,每秒多次把当前水温发送给微处理器 |
| Microprocessor | 微处理器 | compares each reading with the pre-set value of 25 °C; if the reading is below 25 °C it signals the heater to switch on, if it is at or above 25 °C it signals the heater to switch off | 把每个读数与 25 °C 的预设值相比较;若读数低于 25 °C,就发信号让加热器开启;若等于或高于 25 °C,就发信号让加热器关闭 |
| Actuator | 执行器 | switches the heating element on or off when it receives the signal | 收到信号时,把加热元件开启或关闭 |
| Feedback | 反馈 | the heater warms the water, so the sensor's next reading is higher; the microprocessor then switches the heater off, and the water slowly cools until the cycle repeats | 加热器使水变暖,于是传感器下一个读数变高;微处理器随即关闭加热器,水慢慢变凉,直到循环重复 |
Try it yourself
动手试试
Follow the control loop
跟踪控制回路
Step through one turn of the loop for Chloe's fish tank. Watch how each part hands over to the next.
走一遍 Chloe 鱼缸这个回路的一轮。注意每个部分如何交接给下一个。
Explainer · 6.1.2
讲解 · 6.1.2
Advantages and disadvantages
优点与缺点
These apply to most automated systems. In an exam, pick the ones that fit the scenario and say why they matter there.
这些适用于大多数自动化系统。在考试中,挑出符合该情境的那几条,并说明它们在那个场景里为什么重要。
| Advantages | 优点 | Disadvantages | 缺点 |
|---|---|---|---|
| responds faster than a person could | 反应比人更快 | expensive to buy, set up and test | 购置、安装和测试的费用高 |
| gives consistent, repeatable results | 结果一致、可重复 | needs more maintenance, and a specialist to fix a fault | 需要更多维护,出故障时还需要专业人员来修 |
| runs 24 hours a day without breaks or tiredness | 全天 24 小时运行,不休息、不疲劳 | a faulty or dirty sensor feeds it wrong data, which can cause the wrong action | 传感器故障或脏污会给它错误数据,可能导致错误动作 |
| keeps people out of dangerous or unpleasant places | 让人远离危险或不适的环境 | a set of conditions not thought of during testing can make it behave wrongly (so a human still supervises) | 测试时没想到的某种情况可能让它出错(因此仍需人来监督) |
| fewer staff needed, so lower running cost over time | 所需人手更少,长期运行成本更低 | less flexible than a person, and people can lose the skill to do the task by hand | 不如人灵活,而且人可能失去手动完成该任务的技能 |
An automated system does not need less maintenance, and it is not always cheaper: the saving comes later, after a large set-up cost.
自动化系统并非更少维护,也并非总是更便宜:节省是后来才有的,前提是先付出一大笔安装成本。
Try it yourself
动手试试
Advantage or disadvantage?
优点还是缺点?
Tap each statement to tag it as an advantage or a disadvantage of using an automated system, then check.
点击每条陈述,把它标记为使用自动化系统的优点还是缺点,然后检查。
Explainer · 6.1.2
讲解 · 6.1.2
Answering for a given scenario
针对给定情境作答
A 6.1.2 question always names a setting. The syllabus builds its scenarios around places like farms and weather stations, factories and vehicles, home and street lighting, games consoles, and science labs. Markers report that the marks are lost when an answer is generic, so tie each point to the setting the question gives.
一道 6.1.2 的题总会点名一个场景。考纲的情境取自工业、交通运输、农业、气象、游戏、照明和科学。考官报告指出,失分往往是因为作答太笼统,所以要把每一点都和题目里的场景挂钩。
| Generic point | 笼统的说法 | Same point, tied to a fish tank | 同一点,结合鱼缸场景 |
|---|---|---|---|
| "It gives consistent results." | "它的结果稳定一致。" | "The water stays at 25 °C day and night, so the fish are not stressed by swings in temperature." | "水温昼夜都保持在 25 °C,鱼不会因温度骤变而受到应激。" |
| "A faulty sensor is a risk." | "传感器故障是个风险。" | "If the temperature sensor fails, the heater could stay on and cook the fish before Chloe notices." | "如果温度传感器失灵,加热器可能一直开着,在 Chloe 发现之前就把鱼烫死。" |
| "It saves the user time." | "它为用户节省时间。" | "Chloe does not have to check the tank and adjust the heater every few hours." | "Chloe 不必每隔几小时就去查看鱼缸、调节加热器。" |
Also answer exactly what is asked. A question about what the microprocessor does wants only that, not the whole system. Read whether the command word is describe, advantages or characteristics.
另外,题目问什么就答什么。"描述微处理器的作用"只要那一个作用,不要整个系统。看清命令词是描述、优点还是特征。
Try it yourself
动手试试
Fit it to the fish tank
套用到鱼缸情境
Tap each point about Chloe's automated heater to tag it as an advantage or a disadvantage in this scenario, then check.
点击关于 Chloe 自动加热器的每一点,把它标记为在这个场景中的优点还是缺点,然后检查。
Check your understanding
自测
In an automated system, what is the microprocessor's job?
在自动化系统中,微处理器的工作是什么?
Check your understanding
自测
What is meant by feedback in an automated system?
在自动化系统中,反馈是什么意思?
Check your understanding
自测
Which of these is a disadvantage of an automated system?
以下哪一项是自动化系统的缺点?
Common mistakes
常见错误
6.1.1 and 6.1.2
考官针对 6.1.1 和 6.1.2 报告了以下模式
RecurringThe biggest loss of marks: answers are generic and not tied to the scenario. Markers repeatedly ask candidates to take the detail the question gives and work it into the answer. "Sensors send data to a microprocessor which controls actuators" is the same sentence for every system; a good answer names this system's sensor, this pre-set value, this action.
反复出现最大的失分点:作答太笼统,没有和场景挂钩。考官一再要求考生读懂题目的情境并加以运用。"传感器把数据发给微处理器,微处理器控制执行器"这句话对每个系统都一样;好的作答会说出这个系统的传感器、这个预设值、这个动作。
Answering more than was asked. A question about the microprocessor alone needs only that. Describing the whole system, or repeating the question ("if the temperature is below the value, the heater turns on"), does not add marks.
答得比问的多。"描述微处理器的作用"只需要那一个作用。把整个系统都描述一遍、或复述题目("如果温度低于该值,加热器就开"),都不会加分。
Sensors send data all the time. Markers note the misconception that a sensor "only sends a reading when the thing it measures changes". A sensor sends readings continuously; it is the microprocessor that decides when something has changed.
传感器一直在发送数据。考官指出一个误解:以为传感器"只在所测量的东西发生变化时才发读数"。传感器持续不断地发送读数;是微处理器在判断是否发生了变化。
On the actuator, a common wrong idea is that it "changes what is shown on a screen". An actuator produces a physical movement. And an automated system does not need less maintenance than a manual one; it needs more.
关于执行器,一个常见的错误想法是它"改变屏幕上显示的内容"。执行器产生的是物理动作。另外,自动化系统并非比人工系统需要更少维护;它需要更多。
Generic, and repeats the question: "The sensor sends data to the microprocessor. If the temperature is too low, the microprocessor turns on the heater with an actuator."
笼统,而且复述题目:"传感器把数据发给微处理器。如果温度太低,微处理器就用执行器打开加热器。"
Tied to the system: "The temperature sensor sends the water temperature to the microprocessor several times a second. The microprocessor compares each reading with its pre-set value of 25 °C. When a reading is below 25 °C, it signals the actuator, which switches on the heating element. The warmed water raises the next reading, so the microprocessor then switches the heater off."
与系统挂钩:"温度传感器每秒多次把水温发给微处理器。微处理器把每个读数与它 25 °C 的预设值相比较。当某个读数低于 25 °C 时,它向执行器发送信号,执行器开启加热元件。变暖的水使下一个读数升高,于是微处理器随即关闭加热器。"
Go deeper
深入练习
Describe a control loop for a new scenario
为一个新场景描述一个控制回路
Pick a setting the syllabus covers (a farm, a weather station, a factory, a vehicle, a lighting rig, a games console, a science lab). Name a suitable sensor, the pre-set value the microprocessor checks against, and the actuator's action. Then write two advantages and two disadvantages, each one tied to your setting. Check against 6.1.1 and 6.1.2.
从考纲清单里挑一个场景(工业、交通运输、农业、气象、游戏、照明、科学)。说出一个合适的传感器、微处理器用来比对的预设值,以及执行器的动作。然后写两个优点和两个缺点,每一条都和你的场景挂钩。对照 6.1.1 和 6.1.2 核对。
Revision questions
复习题
Past-paper style. Write an answer, then reveal the marking points and mark yourself.
采用历年真题风格。写下答案,然后展开评分要点给自己打分。
[1]State what an automated system is.
[1]陈述自动化系统的含义。
Marking points
评分要点
- An automated system carries out a task on its own, using sensors, a microprocessor and actuators, without a person controlling it.
- 自动化系统利用传感器、微处理器和执行器,自行完成某项任务,无需有人操控。
[2]Describe what the microprocessor does in an automated system.
[2]描述微处理器在自动化系统中的作用。
Marking points
评分要点
- The microprocessor receives the readings from the sensor (via an ADC), compares each reading with a stored (pre-set) value, and decides whether to send a signal to an actuator.
- 微处理器接收来自传感器的读数(经 ADC),把每个读数与存储的(预设的)值比较,并决定是否给执行器发信号。
[6]A greenhouse keeps its air at 22 °C automatically using a heater and a vent. Describe how the sensor, microprocessor and actuators work together to control the temperature.
[6]一个温室用加热器和通风口自动把室内空气保持在 22 °C。描述传感器、微处理器和执行器如何协同工作来控制温度。
Marking points
评分要点
- A temperature sensor continuously measures the greenhouse air temperature and sends readings (via an ADC) to the microprocessor.
- The microprocessor compares each reading with the stored value of 22 deg C.
- If a reading is below 22 deg C, it signals the actuator to switch on the heater.
- If a reading is above 22 deg C, it signals the actuator to open the vent.
- As the temperature changes, new readings are taken and the system keeps adjusting (feedback).
- 温度传感器持续测量温室空气的温度,并把读数(经 ADC)发给微处理器。
- 微处理器把每个读数与存储的值 22 摄氏度比较。
- 如果读数低于 22 摄氏度,它给执行器发信号,开启加热器。
- 如果读数高于 22 摄氏度,它给执行器发信号,打开通风口。
- 随着温度变化,不断采集新读数,系统持续调整(反馈)。
[4]State two benefits and two drawbacks of automating the greenhouse in Question 3.
[4]给出用自动化系统控制第 3 题中温室的两个优点和两个缺点。
Marking points
评分要点
- Benefits (any two): keeps the temperature more precise / constant than a person could; works continuously, day and night; frees the grower from constant checking; responds quickly to a change.
- Drawbacks (any two): high cost to install; needs maintenance; fails if a sensor or the power fails; if set up wrongly it could damage the plants.
- 优点(任选两点):把温度保持得比人更精确 / 更恒定;昼夜不间断地工作;让种植者不必一直查看;对变化响应快。
- 缺点(任选两点):安装成本高;需要维护;传感器或电源故障时会失效;若设置错误可能损害植物。
[2]Explain what is meant by feedback in an automated system.
[2]解释自动化系统中反馈的含义。
Marking points
评分要点
- Feedback is when the output of the system changes the conditions, which changes the next reading the sensor takes.
- So the system responds to the effect of its own actions and keeps correcting.
- 反馈是指系统的输出改变了条件,进而改变传感器采集的下一个读数。
- 所以系统对自己行动的效果作出反应,并不断修正。
Flashcards
记忆卡片
Active recall for this subtopic’s key terms.
针对本子主题关键术语的主动回忆练习。
Keep this subtopic’s practice with you
把这个子主题的练习保存下来
Free account: unlock every revision question and flashcard for 6.1, and every other IGCSE 0478 statement.
免费账户:解锁 6.1 以及所有其他 IGCSE 0478 考纲陈述的全部复习题和记忆卡片。