1. ME407 MECHATRONICS SUKESH O P Assistant Professor Dept. of Mechanical Engineering JECC 10/16/2018 1 SUKESH O P/ APME/ME407- MR-2018

2. SYLLABUS  Introduction to Mechatronics, sensors, Actuators, Micro Electro Mechanical Systems (MEMS), Mechatronics in Computer Numerical Control (CNC) machines, Mechatronics in Robotics-Electrical drives, Force and tactile sensors, Image processing techniques, Case studies of Mechatronics systems. 10/16/2018 2 SUKESH O P/ APME/ME407- MR-2018

3. MODULE-I  Introduction to Mechatronics: Structure of Mechatronics system. Sensors - Characteristics - Temperature, flow, pressure sensors. Displacement, position and proximity sensing by magnetic, optical, ultrasonic, inductive, capacitive and eddy current methods. Encoders: incremental and absolute, gray coded encoder. Resolvers and synchros. Piezoelectric sensors. Acoustic Emission sensors. Principle and types of vibration sensors. 10/16/2018 3 SUKESH O P/ APME/ME407- MR-2018

4. Module 1 10/16/2018SUKESH O P/ APME/ME407- MR-2018 4  Encoders: incremental and absolute, gray coded encoder.

5. CNC System 10/16/2018SUKESH O P/ APME/ME407- MR-2018 5

6. Encoders  An encoder is a device, circuit, transducer, software program, algorithm or person that converts information from one format or code to another, for the purposes of standardization, speed, secrecy, security, or saving space.  A device used to change a signal or data to a code.  Encoder is a digital optical device that converts motion into a sequence of digital pulses. 10/16/2018SUKESH O P/ APME/ME407- MR-2018 6

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12. Incremental Encoders Magnetic Contact Optical

13. 10/16/2018SUKESH O P/ APME/ME407- MR-2018 13 Incremental Encoders

14. Digital Readout (DRO) 7-segment display

15. Rotary Absolute Encoders

18. ROTARY ABSOLUTE ENCODERS

19. Linear Absolute Encoders 10/16/2018SUKESH O P/ APME/ME407- MR-2018 19 SUKESH O P/ APME/ME407- MR-2018

20.  Opaque black is 1 and transparent glass represents 0.  The absolute encoder provides exact rotational position of the shaft whereas the incremental encoder gives relative position of the shaft in terms of digital pulses.  The outmost track has an equivalent value of 1. (2 0 = 1).  Similarly, other tracks 2 1 =2, 2 2 =4, 2 3 =8, 2 4 =16  The sum of shaded area sensed by scanner gives the displacement value. 10/16/2018 20

21. Limit Switch

22. LINEAR ENCODERS

24. Module 1 10/16/2018SUKESH O P/ APME/ME407- MR-2018 24  Resolvers and synchros..

25. Resolver  It is also used to measure the angular position of lead screw thereby to measure the position of machine slide.  The resolver consist of stator and rotor windings which are mounted at right angles to each other. 10/16/2018SUKESH O P/ APME/ME407- MR-2018 25

26.  In a resolver, the output signal as a function of rotation is obtained by inductive coupling between the stator and rotor. If an A/C voltage is applied to one of the stator coils, a maximum voltage will appear at the rotor coil, when these two coils are in line and the voltage will disappear for 90degrees shift.  When the shaft is rotated, the induced voltage in one rotor coil follows a sine curve and the voltage induced in the other follows a cosine curve. So the phase angle depends on the angular position of the rotor shaft. 10/16/2018SUKESH O P/ APME/ME407- MR-2018 26

28.  A resolver is a type of rotary electrical transformer used for measuring degrees of rotation

29.  The most common type of resolver is the brushless transmitter resolver.  On the outside, this type of resolver may look like a small electrical motor having a stator and rotor.  On the inside, the configuration of the wire windings makes it different.  The stator portion of the resolver houses three windings: an exciter winding and two two-phase windings (usually labeled "x" and "y") (case of a brushless resolver). SUKESH O P/ APME/ME407- MR-2018

30.  The exciter winding is located on the top; it is in fact a coil of a turning (rotary) transformer. This transformer induces current in the rotor without a direct electrical connection, thus there are no wires to the rotor limiting its rotation and no need for brushes.  The two other windings are on the bottom, wound on a lamination. They are configured at 90 degrees from each other.  The rotor houses a coil, which is the secondary winding of the turning transformer, and a separate primary winding in a lamination, exciting the two two-phase windings on the stator.

31.  Resolvers can perform very accurate analog conversion from polar to rectangular coordinates. Shaft angle is the polar angle, and excitation voltage is the magnitude.  The outputs are the [x] and [y] components.  Resolvers with four-lead rotors can rotate [x] and [y] coordinates, with the shaft position giving the desired rotation angle. Types of resolver  Receiver resolvers  Differential resolvers SUKESH O P/ APME/ME407- MR-2018

32. Synchros  In function, the synchro is an electromechanical transducer.  A mechanical input such as a shaft rotation is converted to a unique set of output voltages, or a set of input voltages is used to turn a synchro rotor to a desired position. SUKESH O P/ APME/ME407- MR-2018

33.  The complete circle represents the rotor.  The solid bars represent the cores of the windings next to them. Power to the rotor is connected by slip rings and brushes, represented by the circles at the ends of the rotor winding.  The rotor induces equal voltages in the 120° and 240° windings, and no voltage in the 0° winding. [Vex] does not necessarily need to be connected to the common lead of the stator star windings.

34.  A synchro is, in effect, a transformer whose primary- to-secondary coupling may be varied by physically changing the relative orientation of the two windings. Synchros are often used for measuring the angle of a rotating machine such as an antenna platform. In its general physical construction, it is much like an electric motor. SUKESH O P/ APME/ME407- MR-2018

35.  The primary winding of the transformer, fixed to the rotor, is excited by an alternating current, which by electromagnetic induction, causes currents to flow in three Y-connected secondary windings fixed at 120 degrees to each other on the stator.  The relative magnitudes of secondary currents are measured and used to determine the angle of the rotor relative to the stator, or the currents can be used to directly drive a receiver synchro that will rotate in unison with the synchro transmitter.

36. Synchro - Eight functional Categories  Torque Transmitter (TX)  Control Transmitter (CX)  Torque Differential Transmitter (TDX)  Control Differential Transmitter (CDX)  Torque Receiver (TR)  Torque Differential Receiver (TDR)  Control Transformer (CT)  Torque Receiver-Transmitter (TRX) SUKESH O P/ APME/ME407- MR-2018

37. Acoustic emission sensor  An AE sensor is a type of sensor, which converts the surface movement caused by an elastic wave into an electrical signal, which ca be processed by the measuring instrument.  The piezoelectric element of Acoustic Emission (AE) sensor should have high sensitivity and it should convert the surface movement most efficiently to an electrical voltage. 10/16/2018SUKESH O P/ APME/ME407- MR-2018 37

38. Acoustic emission sensor  Acoustic emission (AE) is the phenomenon of radiation of acoustic (elastic) waves in solids that occurs when a material undergoes irreversible changes in its internal structure, for example as a result of crack formation or plastic deformation due to aging, temperature gradients or external mechanical forces.

39. Acoustic emission

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41.  AE sensors are used in a wide range of fields, including the inspection of manufactured products, monitoring the safety of structures, and the development of new materials.  Acoustic Emission (AE) is the sound emitted as an elastic wave by a solid when it is deformed or struck. The use of AE sensors to detect these elastic waves and to non- destructively test on materials is called the AE method. Quite some time before failure occurs, tiny deformations and minute cracks will appear and spread in materials. By picking up the trends in AE, the AE method can detect and predict flaws and failures in materials and structures.  Typical non-destructive testing methods Ultrasonic Testing (UT) Radiographic Testing (RT) Eddy Current Testing (ET) Acoustic Emission Testing (AET)

42.  The AE method offers the following advantages.  Can observe the progress of plastic deformation and microscopic collapse in real time.  Can locate a flaw by using several AE sensors.  Can diagnose facilities while they are in operation

44. Types of AE sensors AE sensors are broadly classified into two types:  Resonance models (narrow-band) that are highly sensitive at a specific frequency.  Wide bandwidth models that possess a constant sensitivity across a wide band of frequencies. The choice of model depends on the goal of the application. SUKESH O P/ APME/ME407- MR-2018

45.  Resonance model The mechanical resonance of the detector element is used to obtain high sensitivity. Generally, these types of sensors have resonant frequencies in the range of 60 kHz to 1 MHz.  AE sensors having a piezoelectric accelerometer design are used if lower resonance characteristics are required.

46.  Wide bandwidth model A damper is bonded on top of the detector element to suppress the resonance.

47. The application of AE sensors  Product testing  Tool monitoring  Facility diagnosis  Safety monitoring in civil engg. projects  Diagnosis of the integrity of large structures. SUKESH O P/ APME/ME407- MR-2018

48. Product testing a) Detecting event of "head touch" in magnetic discs AE sensors are used in the quality control management of magnetic discs. The sensors can detect the sounds of tiny prominences on a rapidly spinning magnetic disc striking the magnetic head.

49. b) Detection of abnormal sounds in small electric motors The passing or failure of the product can be decided based on the level of abnormal sounds coming from motors and fans. SUKESH O P/ APME/ME407- MR-2018

50. c) Inspection of the bonding of laminated boards An AE sensor can tell by the acoustic emissions generated when a load is applied to a laminated board whether there is poor bonding between laminations or not.

51. d) Detection of sub-standard pipe welds When pipes, etc., are improperly welded, the substandard welding can be detected by the AE that are generated.

52. e) Detection of tiny hole in drum cans The passing or failure of the drum can be decided by leak detection when air is pumped into the drum.

54.  The term vibration relates with the displacement, velocity and acceleration. So vibrations can be measured by using the transducers which are sensitive to displacement, velocity and acceleration.  A vibration is measured by its frequency and amplitude.  Every vibrating body/element has mass and frequency of vibration is a function of this mass.  The amplitude of vibration is a function of this mass. SUKESH O P/ APME/ME407- MR-2018

63. An accelerometer is a vibration measuring device which uses a piezoresistive or capacitive effect for measurement.

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68. Vibration sensors  Vibrations are measured by measuring the displacement, velocity or acceleration of the vibrating body with the help of vibration measuring instruments.  The vibration measuring instrument having mass, spring and dash pot etc, is known as seismic instrument or seismic transducer. 10/16/2018SUKESH O P/ APME/ME407- MR-2018 68

69.  Vibrometer (seismometer)  Accelerometer  Laser Doppler Vibr0meter (LDV) 10/16/2018SUKESH O P/ APME/ME407- MR-2018 69

70. Vibrometer (seismometer)  It is designed with low natural frequency and hence it is known as low frequency transducer.  The relative motion between the mass and vibrating body is converted into proportional voltage and it can be recorded. 10/16/2018SUKESH O P/ APME/ME407- MR-2018 70

71. Accelerometer  It is designed with high natural frequency and hence it is known as high frequency transducer. 10/16/2018SUKESH O P/ APME/ME407- MR-2018 71 SUKESH O P/ APME/ME407- MR-2018