ELEC Sensors and Actuators

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1 ELEC Sensors and Actuators Text Book: SENSORS AND ACTUATORS: System Instrumentation, C. W. d e Silva, CRC Press, ISBN: , 2007 Kalyana C. Veluvolu #IT1-817 Tel: veluvolu@ee.knu.ac.kr Website: School of Electronics Engineering Kyungpook National University 1 References: MECHATRONICS - An integrated approach, C. W. de Silva, Taylor & Fra ncis, CRC Press, Boca Raton, FL, 2005 to Mechatronics and Measurement Systems, Histand, M. B. & Alciatore, D. G., McGraw-Hill, 2003 LECTURE NOTES DOWNLOAD Grading Policy Week Topic 1 2 Performance specification and analysis 3 Sensors and transducers 4 Analog sensors for motion 5 Effort sensors Assignments constitute 20% of the grading. A total 3-4 Assignments will be given and students are required to submit it by the due date. Syllabus 6 Torque sensors 7 Tactile sensing 8 Midterm exam 9 Digital transducers 10 Actuators Copying of the solutions from solution manuals and from friends will be penalized. 11 Continuous drive actuators 12 Continuous drive actuators LECTURE NOTES DOWNLOAD Hydraulic actuators 14 Component interconnection and signal conditioning 15 Final exam 4

How Important are Sensors in Today s World?

Wrong Action from the Pilot Damn it, we re going to crash, this can

actual crash) 5 6 Autonomous Cars (Driverless Cars),

excitation Reference ler (Digital or Analog) signal Actuator Drive

2 How Important are Sensors in Today s World? Reasons for Crash of AF Faulty Speed Sensor (Due to Icing) 2. Wrong Action from the Pilot Damn it, we re going to crash, this can t be happening : Last words from Pilot (10 Seconds before the actual crash) 5 6 Autonomous Cars (Driverless Cars), Instrumentation, and Design Power Power Power Disturbance excitation Reference ler (Digital or Analog) signal Actuator Drive excitation Response Power (for active sensors) Sensor/ Transducer Mechanical system (, Process) Feedback signal 7 Power 8

Actuators Actuators are needed to perform the control actions as well as drive the plant directly.

does the actual work Sensors Sensor is an element in mechatronic or measurement system that detects the

Often the active element of a sensor is referred as a transducer 9 Sensors and Actuators used in some

acceleration, elevation, heading, force, pressure, temperature, fluid flow, voltage, current, global

Displacement, speed, force, pressure, temperature, fluid flow, fluid level, voltage, current Temperature,

displacement, speed, force, torque, voltage, current Temperature, relative humidity, moisture content, air

motors, valve actuators, pumps, heat sources Motors, pumps, heat sources DC motors, AC motors DC motors,

Actuators employed in Automobiles Sensors and Actuators employed in Aircrafts Different kinds of Sensors

3 Actuators Actuators are needed to perform the control actions as well as drive the plant directly. Two types: Direct type: Motors of a robot arm like Indirect: Opening a valve of a hydraulic system which does the actual work Sensors Sensor is an element in mechatronic or measurement system that detects the magnitude of a physical parameter and changes it into a signal that can be processed by the system. Often the active element of a sensor is referred as a transducer 9 Sensors and Actuators used in some common engineering applications Process Typical sensors Typical actuators Aircraft Displacement, speed, acceleration, elevation, heading, force, pressure, temperature, fluid flow, voltage, current, global positioning system (GPS) Automobile Home heating system Milling machine Robot Wood drying kiln Displacement, speed, force, pressure, temperature, fluid flow, fluid level, voltage, current Temperature, pressure, fluid flow Displacement, speed, force, acoustics temperature, voltage, current Optical image, displacement, speed, force, torque, voltage, current Temperature, relative humidity, moisture content, air flow DC motors, stepper motors, relays, valve actuators, pumps, heat source jet engines DC motors, stepper motors, valve actuators, pumps, heat sources Motors, pumps, heat sources DC motors, AC motors DC motors, stepper motors, AC motors, hydraulic actuators AC motors, DC motors, pumps, heat sources 10 Sensors and Actuators employed in Automobiles Sensors and Actuators employed in Aircrafts Different kinds of Sensors Engine actuators Air control valve Digital linear actuator Brushless DC drives Pumps Electrical water and Transmission oil pumps Electronic Throttle (ETC) actuator 11 12

Sensors and Actuators employed in Robotics Bioloid, the most advanced robot, which is upgraded with powerful humanoid functions and software Bioloid is

to a high of $9.9 billion in 2014, followed by a 16% increase in 2015 to $11.

1 billion 13 14 System Architecture Open-loop Reference H/W Actuator Reference ler Actuator led variable () Feedback signal Analog sensor/ transducer is the

To accomplish this, we must have access to the drive system or actuator of the plant In feedback control systems, the control loop has to be closed The

4 Sensors and Actuators employed in Robotics Bioloid, the most advanced robot, which is upgraded with powerful humanoid functions and software Bioloid is equipped with servo actuator, gyro sensor, IR sensor, and DMS sensor Sensors/Actuators Trends Worldwide sales of sensors/actuators are forecast to grow 14% to a high of $9.9 billion in 2014, followed by a 16% increase in 2015 to $11.4 billion Between 2013 and 2018, the sensors/actuators market is projected to rise by a compound annual growth rate (CAGR) of 11.7% to reach $15.1 billion System Architecture Open-loop Reference H/W Actuator Reference ler Actuator led variable () Feedback signal Analog sensor/ transducer is the system or process that we are interested in controlling means to make the system respond in a desired manner. To accomplish this, we must have access to the drive system or actuator of the plant In feedback control systems, the control loop has to be closed The output measurements are made primarily using analog devices, typically consisting of sensor-transducer units 15 No measurement of the response of the system to make it behave in the desirable manner has to be stable and completely and accurately known Inputs to the plants has to be precisely generated 16

Reference Feedback (Closed-loop ) ler Example: the speed of a rotating disk Open-loop control A DC motor is selected as an actuator to provide the disk rotation DC amplifier

(bang-bang) Proportional (P) control Proportional control with integral (I) and derivative (D) action PID control 17 Open-loop (without feedback) control of the speed of a

rotating disk Reference input ADC Digital control processor Address Analog multiplexing DAC Drive system conditioning Analog sensors/ transducers s Block diagram model 19

5 Reference Feedback (Closed-loop ) ler Example: the speed of a rotating disk Open-loop control A DC motor is selected as an actuator to provide the disk rotation DC amplifier provides required power to the motor Feedback signal Measurement From sensors Measure the response and compare it with a reference to minimize the error On-off control (bang-bang) Proportional (P) control Proportional control with integral (I) and derivative (D) action PID control 17 Open-loop (without feedback) control of the speed of a rotating disk Block diagram model 18 Example: the speed of a rotating disk Closed-loop control Real-time clock Digital Closed-loop (with feedback) control of the speed of a rotating disk Reference input ADC Digital control processor Address Analog multiplexing DAC Drive system conditioning Analog sensors/ transducers s Block diagram model 19 Address Digital multiplexer Digital sensors/ transducers In digital control, digital computer serves as the controller Computers have to be fast and dedicated machines for real-time operations 20

6 Major advantages of digital control Less susceptible to noise or parameter variation in instrumentation Very high accuracy and speed Handles repetitive tasks extremely well through programming Complex control laws and signal conditioning methods can be programmed Large amount of data can be stored using compact, high-density datastorage methods Data can be stored or maintained for very long periods of time Digital control has easy and fast data retrieval capabilities Digital control is cost-effective Digital processing uses low operational voltages(e.g., 0 to 12 V DC) 21 Reference ler Feedforward Measurement for feedforward Feedback signal Measurement From sensors Unknown Input In addition to feedback control, feedforward control is used to reduce the effects of a disturbance input that enters the plant The disturbance input is measured and fed into the controller 22 Distributed Hierarchical For complex processes with a large number of input or output variables, centralized control is difficult to implement Form of distributed control is appropriate in large systems such as manufacturing work cells, factories, multi-agent robotic applications Internet (TCP/IP,UDP) Fieldbus (Foundation fieldbus, industrial Ethernet, etc. PD1 (with direct I/O) PDr (with direct I/O) PLC DCS Level 3 Level 2 Level 1 Local control system DDC computer Process plant Geographic distribution -setting computer Supervisory control computer 1 2 p 1 2 l Set points (reference inputs) actuator subsystem Functional distribution s PD = Process device PLC = Programmable logic controller DCE = Distributed control system (Supervisory controller) 23 Feedback signals Sensors/ transducers 24

Hierarchical Instrumentation and Design Identification of

interfacing, tuning of the components, etc.

design parameters, modelling of various components, and

important in analyzing, designing, and evaluation of a control

Process Sensor Response Actuator 25 conditioning/filtering 26

Stepper motors, AC motors, DC motors, solenoids, valves, and

resolvers, synchros, gyros, strain gauges, tachometers,

thermocouples, thermistors, resistance temperature detectors

7 Hierarchical Instrumentation and Design Identification of hardware components w.r.t their functions, operation, interfacing, tuning of the components, etc., in short, instrumenting a control system Identification of design parameters, modelling of various components, and analysis are often useful in the design process Modelling is important in analyzing, designing, and evaluation of a control system User commands Digital control computer conditioning Process Sensor Response Actuator 25 conditioning/filtering 26 Components lers: P, PI, PD, PID, Digital Actuating devices: Stepper motors, AC motors, DC motors, solenoids, valves, and relays Sensors: Potentiometers, differential transformers, resolvers, synchros, gyros, strain gauges, tachometers, piezoelectric devices, fluid flow sensors, pressure gauges, thermocouples, thermistors, resistance temperature detectors conditioning devices: Charge amps, power amps, filters (lowpass., high-pass, band-pass, notch) Power supplies Protection devices 27 28

Design considerations Comparison of some common control actions Performance Quality Cost Speed Ease of operation PID control 1 Action On-Off 2 Law 1 Advantages Simple Inexpensive Proportional Simple

response) Instability problems = error signal (controller input) = control/actuating signal (controller output or plant input) = proportional gain = derivative time constant = integral time constant

8 Design considerations Comparison of some common control actions Performance Quality Cost Speed Ease of operation PID control 1 Action On-Off 2 Law 1 Advantages Simple Inexpensive Proportional Simple Fast response Integral 1 Eliminates offset Filters out noise Disadvantages Continuous chatter Mechanical problems Poor accuracy Offset error (Steady state error) Poor stability Low bandwidth (slow response) Instability problems = error signal (controller input) = control/actuating signal (controller output or plant input) = proportional gain = derivative time constant = integral time constant 29 Rate (Derivative) High bandwidth (Fast response) Improves stability Insensitive to DC error Allows high-frequency noise Amplifies noise Difficult analog implementation 30 Programmable logic controllers (PLC) Example: Operation of a turbine blade manufacture PLC is a digital-computer-like system - sequence a complex task: discrete operations, several devices PLCs are rugged computers typically used in factories and process plants Computation and control tasks - PID control: continuous-state control, process variables continuously monitored and made to stay close to desired values - Discrete-state control * sequence of states (Steps) * in steps there may be continuous-state control PLCs are particularly intended for accomplishing discrete-state control Move the cylindrical steel billets into furnace Heat the billets When a billet is properly heated move it to the forging machine Forge the billet into shape Perform surface finishing operations to get the required aero foil shape When the surface finish is satisfactory, machine the blade root 31 32

Programmable Logic ler Hardware 33 Performance characteristics Stability - A stable system will respond in a reasonable manner to an applied input - Asymptotic stability: Response decays back to

react quickly to a control input Sensitivity and robustness - Low sensitivity to noise, external disturbances, modeling errors, and parameter variations - High sensitivity to control inputs Accuracy

well as to drive the plant directly Sensors and transducers are necessary to measure output signals (process responses) and to measure input signals for feedforward control Open-loop (OL) and

9 Programmable Logic ler Hardware 33 Performance characteristics Stability - A stable system will respond in a reasonable manner to an applied input - Asymptotic stability: Response decays back to initial steady state for initial condition excitation - Bounded input bounded output (BIBO) stability: The response to bounded input should be bounded Speed of response (bandwidth): System should react quickly to a control input Sensitivity and robustness - Low sensitivity to noise, external disturbances, modeling errors, and parameter variations - High sensitivity to control inputs Accuracy - Low error, tracking error and steady state error Cross sensitivity (dynamic coupling) - Reduced coupling among system variables 34 Summary Actuators are needed to perform the control action s as well as to drive the plant directly Sensors and transducers are necessary to measure output signals (process responses) and to measure input signals for feedforward control Open-loop (OL) and Closed-loop (CL) systems OL control system uses a controller and actuator to obtain desired response CL control systems use an additional measure of the actual output for feedback Desired Input ler Process Process Actual Feedback (measurement) 35

Keywords: PLC, Three-Phase Induction Motor, AC Current Sensor, Proximity Sensor, AC Voltage Sensor.

Keywords: PLC, Three-Phase Induction Motor, AC Current Sensor, Proximity Sensor, AC Voltage Sensor. IJESRT INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY Protection and Control of Three-Phase Induction Motor using Crouzet Millenium PLC K.L.Priyanka *, Dr. M.Chakravarthy * PG-Student,