Control. A simple control system.

Transcription

1 What is control? is making instructions that change the physical world and in key stage 2 it includes the use of sensors to influence what needs to be done. For example, instructions control an automatic door to open when motion sensors detect someone approaching but not open if they detect someone is in the way. Sensors, such as motion detectors, temperature, sound or light sensors are the inputs to control systems. These inputs are processed to control outputs, such as motors, speakers or lights. A simple control system. systems include a toaster, camera, electronic toys, hearing aids, remote controls, medical scanners, mobile phones, traffic lights, ATMs, cars, a car assembly line, a space shuttle, an automated passenger barrier at a railway station, an automated greenhouse in fact anything automated that creates a physical output using some kind of sensor or input. systems are all around us from the everyday toaster to a space shuttle. Car assembly By Brian Snelson (originally posted to Flickr as Final assembly) [CC-BY-2.0 ( creativecommons.org/licenses/by/2.0)], via Wikimedia Commons all other images public domain wikimedia or pixabay. systems can be very simple or very complex. A simple class sound monitor might use a microphone to sense the current sound level as an input to a program written in Scratch. The program might process the input to create an output showing the change in sound level as a changing image, such as the sprite getting bigger as the sound gets louder, perhaps with a message being displayed if the sound goes beyond a threshold. A far more complex example of sound based control system is a cochlear implant, where complex hardware, software and algorithms are used to receive and then process sounds to create output in the form of an electrical field which stimulates auditory nerve fibres. page 1/10

2 Some control systems are simple such as a class noise meter, others are very complex such as a cochlear implant. systems can be be made up of many computer systems all working together, such as a car assembly line, or they can be a single embedded computer hidden inside an everyday object, such as a on/off controller in a central heating thermostat. In primary settings, we see control in action as a button is pressed on a programmable toy activating a motor to make the toy move, as a distance sensor detects an object in a robot s mouth and the motor snaps its jaws shut, as a light is switched on having activated a light sensitive sensor when using a control box. Examples of primary control systems. Why is control important? Without control our automatic kettle would not switch itself off when the water boils, our car would not stop as we apply the breaks, an ATM would not dispense the requested cash. We take control systems for granted. lies at the heart of manufacturing, technology and automated systems. Engineers, designers and programmers look at the systems they develop and consider what are the sensors, the inputs, what process will be undertaken and what physical output will be generated. From a nuclear power plant generating electricity to a smoke detector protecting our family from fire, control systems infuse modern life. page 2/10

3 A nuclear power plant and an everyday smoke alarm, examples of control systems that we rely upon. Computers themselves are control systems as they take input, process it and create physical outputs. But we often forget that our washing machines, microwaves and all those other electronic devices have sensors, a processor and some form of physical output: they are control systems. Feedback We use feedback as we monitor how hot or cold we are and decide to put on or take of a layer of clothing. Thermostats measure the temperature of a building, adjusting the heating to achieve the desired condition. A program to control a lift will use distance information to reduce its speed and stop as it approaches the correct floor. As output devices act in accordance with their instructions, the effect of the output can be measured using sensors. This new input can be checked against what was intended and the process adjusts the output in accordance with any variance. This process of checking the effect of an output is called feedback. Feedback enables the processor to make adjustments based on the effect of outputs. Thresholds and Follow (Proportion) systems can respond to changes that a sensor detects in a variety of ways. One approach is to compare the input against a threshold and only respond to create some kind of output when the threshold is reached. For example, an automatic door opens only when a proximity detector senses a person within a certain distance, an automatic light is only switched on when the movement sensor registers a certain amount of movement. A second approach is for the output to continually react in proportion to the changing input, so that the output is following the changes in the input. For example, a cooling system in a power station might continually respond to changes in measured temperatures and not wait until it is too hot and too late! The pitch of a car reversing and parking system continuously varies in relation to the distance to objects. page 3/10

4 What is the difference between control and simulation? Simulations model real-world (or imaginary) systems, but they are not the real thing. For example, when pilots use an aircraft simulator to learn to fly they do not use a real aeroplane and do not risk disaster if they fail to land successfully. On the other hand, control is all about doing it for real, for example a real aeroplane is a control system of great complexity where mistakes must be avoided. Interestingly when creating simulations, control can be used to create the simulation themselves. For example, a modern flight simulator carefully monitors what the pilot does using sensors in the on board controls and adjusts the movement of the simulator, the images displayed to the pilot, the simulated sounds of the engine and the cockpit instrument readings. Inside and outside a flight simulator control is used to provide as real as possible experience of flying a plane. By Senior Airman Jerilyn Quintanilla. (United States European Command Official Website) [Public domain], via Wikimedia Commons ;By Baltic Aviation Academy (Baltic Aviation Academy) [Public domain], via Wikimedia Commons systems that do not use a computer system Not all control systems use computers to process their inputs and create their outputs. For example, a digger, such as a JCB, uses levers, valves and hydraulic fluid to control the movement of arms and jaws. A Spitfire is controlled by wires and a pipe organ use pressurized air and mechanics to respond to key presses to create rich and complex sounds.. A control system that does not use a computer. By Harsiem (Own work) [Public domain], via Wikimedia Commons The Internet of Things The term the Internet of Things has been coined to describe the vast number of embedded computing devices attached to the Internet. These networked devices page 4/10

5 range from thermostats controlled by your mobile phone to entire smart cities like South Korea s Songdo International Business Distinct. Gartner has estimated that by 2020 there will be nearly 26 billion devices on the Internet of Things, ABI Research propose by 2020, there may be 30 billion devices wirelessly connected to the Internet of Things (Internet of Everything). The Internet of Things is billions of devices connected to the Internet. By Wilgengebroed on Flickr [CC-BY-2.0 ( via Wikimedia Commons. Digital and Analogue programs work with information from the real world. Much information from the real world is analogue, meaning it varies continuously, such as temperature or volume. However computer systems work with digital data which is made up of a string of bits that can take one of only two values, either 1 (on) or 0 (off). A key function of input and output devices is therefore to make any required conversions between digital and analogue format. What does control look like in the primary curriculum? is making instructions that change the physical world and in key stage 2 it includes the use of sensors to influence what needs to be done. results in any change to the physical world, such as driving motors, switching on lights and buzzers. However, some may also interpret control to include screen based output. But the emphasis of control projects in primary is perhaps to give pupils the opportunity to work with more tangible physical outputs. For example, in key stage 1 programming a programmable toy to trace a route and in key stage 2 creating a toy that page 5/10

6 moves when a sensor is triggered or designing and making a traffic light simulation. Creating control systems helps pupils develop many key computational thinking skills, such as logical thinking as pupils predict what their control system will do; decomposition, as pupils design their project and work out the parts of their system; sequence as they work out what events will occur and their order; selection as they see the dependencies of events; algorithm design as they detail the steps and rules to monitor inputs and control outputs. tasks are also great fun! EYFS In early years pupils use a range of control systems. They use remote controlled toys and in so doing they observe the cause and effect of pressing keys and seeing the toy move, make a sound or light up. In role play, they explore the idea of controlling washing machines, ovens and other common appliances making the link between input and output and considering how devices work out what to do. They press the button on pedestrian crossings and delight to see the green man appear and the cars stop as the red light is lit providing them with experiences of the usefulness of control. Many toys are electronic and bleep when switched on, or make a noise when not used for a while, children start to take for granted these control systems that infuse their lives. KS1 In key stage 1, pupils continue to develop their knowledge of control systems as they use devices which require them to undertake an input action to see a resultant output. They start to become aware of the role of sensors as they press buttons in lifts and notice that the doors reopen if someone gets in the way, they move their hands in and out of automatic driers and feel the air start and stop. They move in front of automatic doors and wait for the door to open, put an item on the conveyor belt and see the belt take it to the till and then stop, thinking how do these things know what to do. Although control is not directly mentioned in the key stage 1 programme of study, control has been historically associated with programmable toys and much of the key stage 1 computing curriculum may be delivered using these digital devices. Pupils learn much about the output aspect of control as they program the toys to move. Above are shown a sample of programmable toys Bee-Bot, Roamer, ProBot, BigTrack. Pupils using Daisy the Dinosaur might use the tilt and touch sensors to control the input to a game. In doing this they are working with the input aspect of a control system. page 6/10

7 KS2 In key stage 2, as well as pupils continuing to develop their understanding of control systems by observing and using them in their daily lives they can learn more by creating control systems themselves. Design, write and debug programs that control physical systems In the programme of study there is requirement for pupils to control or simulate physical systems. Much is to be gained from pupils experiencing hands on control projects, where they use sensors and create real world physical systems. From this experience pupils not only engage in a practical creative process bringing to life problem solving tasks they also see how computing involves physical objects, mechanics and electronics. projects afford opportunities to undertake cross-curricula work, related to design and technology curriculum objectives such as pupils being required to: understand and use electrical systems in their products (for example, series circuits incorporating switches, bulbs, buzzers and motors) apply their understanding of computing to program, monitor and control their products. There are also opportunities to undertake cross-curricula work, related to science curriculum objectives such as pupils being required to: make systematic and careful observations and, where appropriate, taking accurate measurements using standard units, using a range of equipment, including thermometers and data loggers. As part of control projects, examples of real life control systems can be investigated to help pupils put control into context and understand its significance in our lives. For example they can look at how automatic doors work, level crossings, supermarket checkout belts, fire or intruder alarms and assembly lines. There are opportunities here for school trips and to make connections with families working in industry or with local manufacturing or design businesses. Cross curricular topics can make ideal contexts for control projects. For example a Space topic could look at control systems used on Space Shuttles. NASA provides opportunities to contact Astronauts, giving pupils the opportunity to ask questions about the practicalities of extreme control systems. When designing control systems, storyboards, annotated sketches, exploded diagrams can be used to help pupils formulate their ideas and develop their algorithms. page 7/10

8 A simple annotated sketch of a control project. The algorithm is included as a simple statement When near robot head spins. Having created an overall design pupils can then develop their algorithms in more detail perhaps by physically re-enacting the process and photographing each step or writing the steps or rules down. As a precursor to the work done more formally in key stage 3 and 4 on design, flowcharts can be explored. For example a flowchart of a class sound monitor might be drawn up as below. A simple flowchart for a sound monitor. If using flowcharts in KS2, ensure that pupils have been introduced to the principles of their use, perhaps using simple everyday examples first, before they have to create them for themselves. Unplugged lessons where pupils use cardboard cut-outs of flowchart symbols can be a useful way to introduce this means of documenting algorithms. page 8/10

9 Also consider whether the algorithm you are designing is best represented through a flow chart. For example, a simple sequence based algorithm might be better as a list of statements, whereas an algorithm with one or two choices might be suitable for a flow chart. It is worth noting that despite flowcharts being very popular in commercial projects in the past, they are now rarely used in industry, having been replaced with a wide range of different diagramming techniques. Example control projects might be a class noise meter, a toy that moves and reacts to input, a cat feeder, a fruit keyboard, a plant watering system, an automated photograph taker, an extractor or cooling fan, an automated story reader, wearable technology badges or hair accessories, a quiz where gesture is used to capture the answers, a movement measurement kit, an automated artist. The list of potential projects is perhaps endless, only constrained by pupil and teacher imaginations and the availability of control software and hardware. Ideas about control software and hardware There are a range of products available to support control projects. Some control software is free, but most hardware needs to be purchased or loaned by schools. equipment can be costly particularly if a class-set is required and it is appreciated that schools have tight financial constraints. When considering what control equipment to buy there are a number of areas that might be considered. Some equipment requires investment of time to get to understand how to use the hardware, or requires an underlying technical confidence in, or knowledge of electronics. However some schools may have access to local expertise, through coding clubs or parent helpers, or teachers with particular experience or passion for control technology. On the other hand some equipment is easy to use, and requires a minimum setup time but does require some technical support to upload software. Some equipment includes many sensors or outputs in a single device, meaning that the cost of each input/output may be lower but that fewer pupils can access these features than if separate devices were purchased. It is perhaps worth trialling a range of control devices, perhaps by buying a single device and trying it out, or seeing devices in use at another school before buying a large number of devices. A number of control devices are detailed below but there are many more and there is a constant stream of new products being developed. equipment used in the ICT curriculum, such as the FlowGo and CoCo Boxes use product specific programming languages, Flowol or Logo giving pupils the opportunity to monitor a range of inputs including light and temperature sensors and control lights, buzzers and motors. page 9/10

10 Microphones and webcams can be used as input devices. These may be built into laptops or mobile devices or are peripherals that are connected via the USB port of computers. These can be used immediately from within some programming languages, such as Scratch, to sense sound or movement. Robotic, electronic, invention and data logging kits often have a range of inputs. These might include light, sound, tilt, distance, movement, temperature, humidity and even GPS sensors. These devices can be monitored in a range of languages. Such kits may have a number of output devices such as motors, lights, switches, speakers, buzzers. For further information on a range of devices that can be used in control project see input, output, control equipment. Find out more about control BBC Bitesize Computing ling physical systems GCSE ling real world things BBC Bitesize Design and technology Systems and control Wikipedia article on control engineering Using flowcharts in KS2 List of some of the hardware that can be connected to Scratch Scratch Nuts and Bolts videos sensing1 and sensing2 Inspirational ideas from educators trying robotics for the first time Example art and robot project Boris the robot does the washing up Information about gesture based control with pupils with special educational needs page 10/10