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MECHATRONICS U5MEA22. Prepared by Mr. S Riyaz Ahammed & Mr . Hushein Assistant Professor, Mechanical Department VelTech Dr.RR & Dr.SR Technical University. Unit 1.
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MECHATRONICS U5MEA22 Preparedby Mr. S RiyazAhammed & Mr.Hushein Assistant Professor, Mechanical Department VelTech Dr.RR & Dr.SR Technical University
Mechatronics basically refers to mechanical electrical systems and is centered on mechanics, electronics, computing and control which, combined, make possible the generation of simpler, more economical, reliable and versatile systems. • The term "mechatronics" was first assigned by Mr.Tetsuro Mori, a senior engineer of the Japanese company Yaskawa, in 1969. • Mechatronics is the combination of mechanical, electronic, computer,control engineering's and system engineering to design and manufacture useful products. Mechatronics:-
Control Systems • Control Systems are mainly of Two Types • Open Loop Control Systems • Closed Loop control Systems • An open-loop controller, also called a non-feedback controller. • Basic difference between two types of systems is closed loop systems have feed back which makes them to be good precise control systems or automated systems. • PID controller, a commonly used closed-loop controller
Controlled variable- water level in tank • Reference value- initial setting of float, lever position • Comparison element- Lever • Error signal- Difference between the actual and initial settings of lever position • Control unit- Pivoted lever • Correction unit- Flap opening or closing water supply • Process- water level in the tank
Description • Potentiometer is used to set the voltage to be supplied to the power amplifier. • Differential amplifier is used to amplify and compare the feed back value and reference value. • Amplified error signal is fed to the motor to adjust the speed of rotating shaft. • Tachometer is used to measure the speed of rotating shaft and speed is fed to amplifier.
Washing Machine control • Example of an event based sequential control system is washing machine. Each event of washing machine may consist of number of sub events or steps. For example pre wash cycle, rinse cycle, main cycle, spinning cycle. • Following figures represent the various events of washing machine system.
During Pre wash cycle operation, the inlet valve is opened when the machine is switched ON and the valve is closed when the required level of water is filled in the drum.Main wash cycle is then started by micro processor by operating the inlet valve to allow the water in to the drum.Water level sensor senses the water level in the drum and it closes the inlet valve after reaching certain level, Micro processor switches ON the heating coil in the drum.
AUTOMATIC CAMERA • Basic elements of control systems used in automatic camera are body, lenses and flash. • Depending up on mode selected, the required combination of aperture and shutter speed and focus are automatically taken care by the camera. • A typical camera system comprises drives and sensors, interfaces for lenses, flash and the user.
Micro processor systems for lenses, user and flash are incorporated for controlling various operations. Micro processor takes input from range sensor and sends output to lens. • Position is fed back to micro processor and it modifies the same. • Light sensor gives input to micro processor, When photographer selects shutter controller, shutter opens up for photograph to be taken.
Engine Management System • System consists of sensors for supplying, after suitable signal conditioning, the input signals to micro controller, and its providing output signals via drivers to actuate actuators. • Engine speed sensor is an inductive sensor and consists of a coil for which inductance changes as the teeth of the sensor wheel pass it and so gives oscillating output.
Temperature sensor is usually a thermistor. • Mass air flow sensor may be a hot wire sensor, as air passes over heated wire it will be cooled, the amount of cooling will depend on the mass rate of flow. • Oxygen sensor is generally closed end tube made of zirconium oxide with porous platinum electrodes on inner and outer surfaces. • Following figure represents an engine management system
Unit 2 MICROPROCESOR IN MECHATRONICS
MICROPROCESSOR • A microprocessor incorporates the functions of a computer's central processing unit (CPU) on a single integrated circuit (IC),or at most a few integrated circuits. Microprocessor is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and provides results as output
INPUT AND OUTPUT PERIPHERAL CIRCUITS • A peripheral is a device that is connected to a host computer, but not part of it. It expands the host's capabilities but does not form part of the core computer architecture. It is often, but not always, partially or completely dependent on the host. • There are three different types of peripherals: • Input, used to interact with, or send data to the computer (mouse, keyboards, etc.) • Output, which provides output to the user from the computer (monitors, printers, etc.) • Storage, which stores data processed by the computer (hard drives, flash drives, etc.)
COMMUNICATIONS-INPUT,OUTPUT AND MEMORY WITH TIMING DIAGRAM • Input/output (I/O) scheduling is the method that computeroperating systems use to decide which order block I/O operations will be submitted to storage volumes. I/O Scheduling is sometimes called 'disk scheduling'.
PURPOSE • I/O schedulers can have many purposes depending on the goal of the I/O scheduler. Some common ones are: • To minimize time wasted by hard disk seeks • To prioritize a certain processes' I/O requests • To give a share of the disk bandwidth to each running process • To guarantee that certain requests will be issued before a particular deadline
A/D CONVERTER • An analog-to-digital converter (abbreviated ADC, A/D or A to D) is a device that converts a continuous physical quantity (usually voltage) to a digital number that represents the quantity's amplitude.
The conversion involves quantization of the input, so it necessarily introduces a small amount of error. Instead of doing a single conversion, an ADC often performs the conversions ("samples" the input) periodically. The result is a sequence of digital values that have converted a continuous-time and continuous-amplitude analog signal to a discrete-time and discrete-amplitude digital signal.
An ADC may also provide an isolated measurement such as an electronic device that converts an input analogvoltage or current to a digital number proportional to the magnitude of the voltage or current. However, some non-electronic or only partially electronic devices, such as rotary encoders, can also be considered ADCs. The digital output may use different coding schemes. Typically the digital output will be a two's complement binary number that is proportional to the input, but there are other possibilities. An encoder, for example, might output a Gray code. • The inverse operation is performed by a digital-to-analog converter (DAC).
The key parameters to test a SAR ADC are following: • DC Offset Error • DC Gain Error • Signal to Noise Ratio (SNR) • Total Harmonic Distortion (THD) • Integral Non Linearity (INL) • Differential Non Linearity (DNL) • Spurious Free Dynamic Range • Power Dissipation
D/A CONVERTER • a digital-to-analog converter (DAC or D-to-A) is a device that converts a digital (usually binary) code to an analog signal (current, voltage, or electric charge). An analog-to-digital converter (ADC) performs the reverse operation. Signals are easily stored and transmitted in digital form, but a DAC is needed for the signal to be recognized by human senses or other non-digital systems.
A common use of digital-to-analog converters is generation of audio signals from digital information in music players. Digital video signals are converted to analog in televisions and mobile phones to display colors and shades. Digital-to-analog conversion can degrade a signal, so conversion details are normally chosen so that the errors are negligible.
Due to cost and the need for matched components, DACs are almost exclusively manufactured on integrated circuits (ICs). There are many DACarchitectures which have different advantages and disadvantages. The suitability of a particular DAC for an application is determined by a variety of measurements including speed and resolution.
RECENT DEVELOPMENTS IN MICROPROCESSORS AND CONTROLLERS • The recent development In microprocessor technology makes Implementation of advanced control strategies feasible at the generating level. A self-tuning (ST) proportional-plus-lntegral-plus-derivative (PID) digital automatic voltage regulator (DAVR) for a large synchronous machine is proposed and the influence of this regulator on the generator dynamic and transient stability is investigated. The algorithm for this regulator combines a least-square estimator with a digital PID control algorithm. The parameters of the PID control algorithm are computed and updated according to the estimated model. The dynamic performance of the machine when equipped with a digital PID governor is also presented. A comparison of the computer results as obtained from the simulation study are compared with the available experimental results.
Unit 3 ELECTRICAL DRIVES AND CONTROLLERS
Electromagnetic principles • "When a conductor is exposed to a changing magnetic field, an electric current will flow in the conductor." • This principle is the basis for the generation of electricity. In a typical large-scale operating electrical generator, an armature coil (a coil of wire of many turns) is wrapped around a soft iron armature and forced to spin in a powerful electromagnetic field. The spinning is achieved by forcing high-pressure steam (in a thermal generator), fast-flowing water (in a hydro generator), or wind (in a wind generator) across a turbine (similar to a propeller blade) attached to the end of the armature. As the armature spins, an electric current is induced (forced) to flow in the armature coil where it is extracted and sent to the electricity grid that supplies electricity across a broad area (the province of Ontario and beyond, for example). It is the direction of flow of this induced current that is addressed by Lenz's law.
SOLENOIDS • In physics, the term refers specifically to a long, thin loop of wire, often wrapped around a metallic core, which produces a uniform magnetic field in a volume of space (where some experiment might be carried out) when an electric current is passed through it. Solenoids are important because they can create controlled magnetic fields and can be used as electromagnets.
In engineering, the term may also refer to a variety of transducer devices that convert energy into linear motion. The term is also often used to refer to asolenoid valve, which is an integrated device containing an electromechanical solenoid which actuates either a pneumatic or hydraulic valve, or a solenoid switch, which is a specific type of relay that internally uses an electromechanical solenoid to operate an electrical switch; for example, an automobile starter solenoid, or a linear solenoid, which is an electromechanical solenoid.