1Prepared by: Mazhar Javed Awan Control Although many people assume that businesses mainly use computers in offices to help workers to perform administrative tasks, they also have many other uses in the workplace. Although many people assume that businesses mainly use computers in offices to help workers to perform administrative tasks, they also have many other uses in the workplace. For example, computers can be used to control many different types of machinery, including industrial robots. For example, computers can be used to control many different types of machinery, including industrial robots. Components of Computer Control Components of Computer Control A computer (or microprocessor). A computer (or microprocessor). Some sensors to enable the computer to detect quantities such as temperature or pressure. Some sensors to enable the computer to detect quantities such as temperature or pressure. Some devices for the computer to turn on and off. Some devices for the computer to turn on and off. An interface to connect the sensors and devices to the computer. An interface to connect the sensors and devices to the computer. Some software to read data from the sensors and turn the devices on and off. Some software to read data from the sensors and turn the devices on and off.

2Prepared by: Mazhar Javed Awan Robots An industrial robot is ‘a reprogrammable, multi-functional manipulator designed to move material, parts, tools or specialised devices through various programmed motions for the performance of a variety of tasks’. An industrial robot is ‘a reprogrammable, multi-functional manipulator designed to move material, parts, tools or specialised devices through various programmed motions for the performance of a variety of tasks’. Uses: Uses: To spray paint or for welding body panels. To spray paint or for welding body panels. Washing machine is restricted to washing clothes. Washing machine is restricted to washing clothes.

3Prepared by: Mazhar Javed Awan Industrial Robots Industrial robots are comprised of three parts: Industrial robots are comprised of three parts: The manipulator – this is the moving ‘arm’ to which various tools can be attached. The manipulator – this is the moving ‘arm’ to which various tools can be attached. The power supply – usually a hydraulic compressor (for robots that need lots of strength) or electrical generator (for lightweight robots). The power supply – usually a hydraulic compressor (for robots that need lots of strength) or electrical generator (for lightweight robots). The controlling computer – which controls the robot. The controlling computer – which controls the robot.

4Prepared by: Mazhar Javed Awan Why use Robots They can repeat tasks in exactly the same way each time They can repeat tasks in exactly the same way each time As long as they have power, they never tire As long as they have power, they never tire They can survive in places where people can't They can survive in places where people can't They can carry out tasks too dangerous for people They can carry out tasks too dangerous for people They never get bored when they repeat the same task over and over They never get bored when they repeat the same task over and over They have many types of sensors to gather and process data They have many types of sensors to gather and process data

5Prepared by: Mazhar Javed Awan Robots The controlling computer uses a very low electrical current and requires an interface to allow it to work with the other parts of the robot. The controlling computer uses a very low electrical current and requires an interface to allow it to work with the other parts of the robot. The interface also allows conversion from digital to analogue and analogue to digital. The interface also allows conversion from digital to analogue and analogue to digital. Robots on the move Robots on the move When robots move from one place to others,then there are following problems. When robots move from one place to others,then there are following problems. How are robots able to navigate themselves? How are robots able to navigate themselves? How do robots avoid colliding with each other? How do robots avoid colliding with each other? How is the power provided? How is the power provided?

6Prepared by: Mazhar Javed Awan Robots how to solve problems Sometimes robots need to move from one location to another (e.g. robotic fork lift trucks in an automated warehouse). Sometimes robots need to move from one location to another (e.g. robotic fork lift trucks in an automated warehouse). These robots require self-contained power sources (e.g. batteries) and additional autonomy (i.e. the ability to make simple decisions based on limited information). These robots require self-contained power sources (e.g. batteries) and additional autonomy (i.e. the ability to make simple decisions based on limited information). Also keep a record of the distance they have travelled and the angles they have turned through. Also keep a record of the distance they have travelled and the angles they have turned through. On each robot there is an ultrasonic detector,which emits a beams of infrared radiation.If anything gets in the way of the beam, the robot just stops. On each robot there is an ultrasonic detector,which emits a beams of infrared radiation.If anything gets in the way of the beam, the robot just stops.

7Prepared by: Mazhar Javed Awan Sensors A sensor is something which can measure physical quantities in the surrounding environment. A sensor is something which can measure physical quantities in the surrounding environment. Robots need information as well as programming in order to function. This information is provided by sensors. Robots need information as well as programming in order to function. This information is provided by sensors. An example might be a heat sensor which measures the temperature in a room or a pressure sensor which senses when someone has walked over it. An example might be a heat sensor which measures the temperature in a room or a pressure sensor which senses when someone has walked over it..

8Prepared by: Mazhar Javed Awan Sensors The types of sensors required by robots include: The types of sensors required by robots include: Mercury tilt switches – these are switches that sense titling movement. Mercury tilt switches – these are switches that sense titling movement. Light sensors – these are sensors that detect different levels of light and dark. Light sensors – these are sensors that detect different levels of light and dark. Push switches – these are switches that operate when something is opened or closed (e.g. the switch that controls the light in a fridge is a push switch). Push switches – these are switches that operate when something is opened or closed (e.g. the switch that controls the light in a fridge is a push switch).

9Prepared by: Mazhar Javed Awan Sensors Temperature sensors – these detect changes in the temperature. Temperature sensors – these detect changes in the temperature. Sound sensors – these detect different levels and frequencies of sound. Sound sensors – these detect different levels and frequencies of sound. Proximity sensors – these detect how close something is or if something is being moved away. Proximity sensors – these detect how close something is or if something is being moved away. Position sensors – these detect the angle between one part of the robot arm from another. Position sensors – these detect the angle between one part of the robot arm from another. pH sensors – these detect how acidic something is. pH sensors – these detect how acidic something is. Humidity sensors – these detect how much moisture is present in the atmosphere or in a sample. Humidity sensors – these detect how much moisture is present in the atmosphere or in a sample.

10Prepared by: Mazhar Javed Awan SensorsMeasuresWhere to used HeatTemperatureLiving room for central heating system HumidityWater vapour in the airSwimming pool, greenhouse Infra-redInfra-red radiation e.g. body heatSecurity alarm systems LightLight levelsExternal security lights PHAcid/alkali levels e.g. pH of soilEnvironmental experiments, river pollution Pressure Burglar alarm systems, automatic doors SmokeSmoke in the atmosphereOffices SoundLevels of soundSecurity alarm systems TiltAngle of tiltWindows in security alarm system TouchDetects if one object bumps into anotherComputer controlled robots Sensor Measurements

11Prepared by: Mazhar Javed Awan The interface Name given to the hardware and associated software needed to peripheral units and computers. Name given to the hardware and associated software needed to peripheral units and computers. The sensors feed their information to the controlling computer via the interface. The sensors feed their information to the controlling computer via the interface. The interface also feeds commands to the manipulator from the controlling computer. The interface also feeds commands to the manipulator from the controlling computer. The information from the sensors and the commands to the manipulator usually pass through a buffer. The information from the sensors and the commands to the manipulator usually pass through a buffer.

12Prepared by: Mazhar Javed Awan The buffer The buffer stores data (information coming in or commands going out) so that the speed of data transfer is at a level that the various parts of the robot can cope with. The buffer stores data (information coming in or commands going out) so that the speed of data transfer is at a level that the various parts of the robot can cope with. For example, if data transfer was too quick, the controlling computer might command the manipulator to do something new before it has completed a previous task. For example, if data transfer was too quick, the controlling computer might command the manipulator to do something new before it has completed a previous task. This could be very dangerous and could cause the manipulator’s actuators (special electrical motors that act like the manipulator’s muscles) to burn out. This could be very dangerous and could cause the manipulator’s actuators (special electrical motors that act like the manipulator’s muscles) to burn out. This is a particular problem with stepper motors (an actuator that can be moved only a very small amount, or very slowly, or very quickly, or forward or in reverse). This is a particular problem with stepper motors (an actuator that can be moved only a very small amount, or very slowly, or very quickly, or forward or in reverse).

13Prepared by: Mazhar Javed Awan Actuator An actuator is often part of a computer control system. An actuator is often part of a computer control system. The actuator is a mechanical device or motor which carries out the action or decision made by the control system. The actuator is a mechanical device or motor which carries out the action or decision made by the control system. For example, in a greenhouse, sensors may measure the temperature. When the temperature rises too much, the control system will send a signal to open the windows or vents. For example, in a greenhouse, sensors may measure the temperature. When the temperature rises too much, the control system will send a signal to open the windows or vents. The actuator is the motor which will open the vents. Likewise, when the temperature drops, the control system will send a message to the actuator (motor) to close the vents. The actuator is the motor which will open the vents. Likewise, when the temperature drops, the control system will send a message to the actuator (motor) to close the vents.

14Prepared by: Mazhar Javed Awan Stepper Motor Is a motor which turns in series of small steps. Is a motor which turns in series of small steps. Pulse sent from the computer instruct the motor to turn through the required angle. Pulse sent from the computer instruct the motor to turn through the required angle. Can also be sped up or slow down or reverse or forward direction. Can also be sped up or slow down or reverse or forward direction. To connect a stepper motor to computer, we use a buffer. To connect a stepper motor to computer, we use a buffer. Stepper motor used in robot arms. Stepper motor used in robot arms.

15Prepared by: Mazhar Javed Awan Computer control There are various types of computer control. There are various types of computer control. These include: These include: Open-loop control. Open-loop control. Close-loop control. Close-loop control.

16Prepared by: Mazhar Javed Awan Open-loop control The first type, Open Loop System, only looks at its input signal in order to decide what to do. The first type, Open Loop System, only looks at its input signal in order to decide what to do. It of what is happening to its output. It of what is happening to its output. An open-loop control program assumes that commands, when given, take affect. An open-loop control program assumes that commands, when given, take affect. If a robot arm is given a command to move and something stops it, an open-loop control program will act as though the arm has moved. If a robot arm is given a command to move and something stops it, an open-loop control program will act as though the arm has moved. In open-loop control, output does not affect input. In open-loop control, output does not affect input. Examples of 'open-loop' systems: Examples of 'open-loop' systems: a) You set the microwave oven to run for two minutes. After cooking for two minutes, the control system turns the microwave off. It has no idea whether your food is still frozen, burnt or cooked perfectly. a) You set the microwave oven to run for two minutes. After cooking for two minutes, the control system turns the microwave off. It has no idea whether your food is still frozen, burnt or cooked perfectly. b) You program the video recorder to start recording the football game at 7.30pm. However, because the news program finished early, you miss the first vital 15 minutes of the match. Because the system is only checking its input(time), it had no idea that the starting time of the match had changed. b) You program the video recorder to start recording the football game at 7.30pm. However, because the news program finished early, you miss the first vital 15 minutes of the match. Because the system is only checking its input(time), it had no idea that the starting time of the match had changed.

17Prepared by: Mazhar Javed Awan Closed-loop control A closed-loop control program uses feedback to check that its commands have taken affect. A closed-loop control program uses feedback to check that its commands have taken affect. Definition: Feedback is where the output of a system affects the input. Definition: Feedback is where the output of a system affects the input. The feedback from sensors attached to a robot arm informs the program of the arm’s actual position, and if something has stopped the arm from moving, the program will take remedial action (e.g. display a warning message). The feedback from sensors attached to a robot arm informs the program of the arm’s actual position, and if something has stopped the arm from moving, the program will take remedial action (e.g. display a warning message). When this happens instantly this is called ‘real time control When this happens instantly this is called ‘real time control This stage is called processing. The computer can only follow the rules that it has programmed into the control system, it cannot make its own decisions. This stage is called processing. The computer can only follow the rules that it has programmed into the control system, it cannot make its own decisions. Example: computer disk drive may use of feedback Example: computer disk drive may use of feedback

18Prepared by: Mazhar Javed Awan Process Control Once the input data from the sensors has been received by the computer, it can then begin to process it. Once the input data from the sensors has been received by the computer, it can then begin to process it. The data will be compared against a set of rules which have been programmed into the control system and a decision will be made. This stage is called processing. The data will be compared against a set of rules which have been programmed into the control system and a decision will be made. This stage is called processing. The computer can only follow the rules that it has programmed into the control system, it cannot make its own decisions. The computer can only follow the rules that it has programmed into the control system, it cannot make its own decisions. Process Control is used in nuclear power stations, oil refineries and in the chemical industries. Process Control is used in nuclear power stations, oil refineries and in the chemical industries. Various sensors are used to relay the electronic signals back to computers Various sensors are used to relay the electronic signals back to computers

19Prepared by: Mazhar Javed Awan The advantages of computer control Can operate 24 hours a day without taking a break. Can operate 24 hours a day without taking a break. Can work without holidays or sick days Can work without holidays or sick days Will work without any wages. Will work without any wages. Will repeat actions over and over and over again Will repeat actions over and over and over again Can process data from sensors very quickly Can process data from sensors very quickly Can take account of hundreds of inputs at the same time Can take account of hundreds of inputs at the same time Can make reliable and accurate decisions Can make reliable and accurate decisions Can be used in dangerous or awkward environments where it wouldn't be a good idea to send humans to. Can be used in dangerous or awkward environments where it wouldn't be a good idea to send humans to. Changes can be made by quickly by simply reprogramming the system Changes can be made by quickly by simply reprogramming the system

20Prepared by: Mazhar Javed Awan The disadvantages of computer control There are high initial costs because computer-controlled are more expensive to buy and set up. There are high initial costs because computer-controlled are more expensive to buy and set up. Fewer workers will be employed if computer-controlled systems are introduced, thus leading to a rise in the numbers of people who are unemployed. Fewer workers will be employed if computer-controlled systems are introduced, thus leading to a rise in the numbers of people who are unemployed. The software for the control system is specialist and may cost a lot of money to develop The software for the control system is specialist and may cost a lot of money to develop If the computer malfunctions the system will not work If the computer malfunctions the system will not work If there is a power cut the system will not work If there is a power cut the system will not work The computer can’t react to unexpected events like a human could. It can only respond in the way it has been programmed to. The computer can’t react to unexpected events like a human could. It can only respond in the way it has been programmed to. It can cause some concern if total control for a system and the decisions are handed over to a computer. It can cause some concern if total control for a system and the decisions are handed over to a computer.

21Prepared by: Mazhar Javed Awan Examples of Computer Control At home At home Washing machines Washing machines Microwave cookers Microwave cookers Dishwashers Dishwashers Electric kettles Electric kettles Fridges Fridges Video recorders Video recorders Remote control television Remote control television Central heating systems Central heating systems Burglar Alarm system Burglar Alarm system External Security lights External Security lights

22Prepared by: Mazhar Javed Awan Examples of Computer Control At work At work Air conditioning systems Air conditioning systems Lifts Lifts Automatic doors Automatic doors Factory robots Factory robots

23Prepared by: Mazhar Javed Awan Examples of Computer Control Outside the home Outside the home Traffic light systems Traffic light systems Car park barriers Car park barriers Cars – engine management systems Cars – engine management systems Lifts Lifts Rides at theme parks Rides at theme parks Computer controlled lighting systems at discos and concerts Computer controlled lighting systems at discos and concerts Remote controlled car Remote controlled car

24Prepared by: Mazhar Javed Awan Simple Greenhouse Temperature Control System A greenhouse temperature control system consists of : A greenhouse temperature control system consists of : A temperature sensor. A temperature sensor. A heater. A heater. The system is used to keep the temperature of the greenhouse above 20°C. If the temperature drops below 20°C then a heater is turned on to warm the greenhouse up. The system is used to keep the temperature of the greenhouse above 20°C. If the temperature drops below 20°C then a heater is turned on to warm the greenhouse up. Input and Output Devices Input and Output Devices InputOutput Temperature Sensors Heater