Óbuda University Subject Requirements: Bánki Donát Faculty of Mechanical & Safety Engineering Institute of Mechatronics & Vehicle Engineering Lectures/week: 3+0+0 Credits: 3 Subject: Introduction to the Mechatronics Subject leader: István Nagy Contact: nagy.istvan@bgk.uni-obuda.hu PPT-s: http:// siva.banki.hu/jegyzetek/mehatronikai_alapismeretek/. Requirement: Semester evaluation, based on semester examination s papers. It is planned two examination s papers during the semester. The final evaluation will be calculated based on the average of these two results. Subject Description: Description: The subject will give a short introduction to the mechatronics. Will point to the basic and the detailed division of the mechatronical systems, like: input-output elements (sensors & actuators), some basic control techniques, computers and logical systems, SW-s and data acquisitions, signal processing, and will give a short introduction to the each separated part of the system. The subject is serving like the basis for the subjects: Analog & Digital techniques, Control Engineering, Analog and Digital signal processing, Electronics, Logical System Design, Mechanics etc. Literature: Sergey E. Lyshevski: 1.Control System Theory with Engineering Application (CRC Press) 2.Electromechanical Systems, Electric Machines and Applied Mechatronics (www.crcpress.com/us/product.asp?sku=2275&dept%5fid=1) 3.Nano- and Micro-electromechanical Systems (www.crcpress.com/s/product.asp?sku=0916&dept%5fid=1) Robert H. Bishop, Ed-in-Chief Subject Topics: The aim of this subject is giving the students a basic information about the mechatronic systems to taste the flavor of the mechatronical design. The several parts of the subject later will appear as independent subject. Part 1 : General System Description Part 2 : Physical System Modeling Part 3 : Sensors & Actuators Part 4 : Systems & Controls Part 5 : Computers & Logic Systems Part 6 : Software & Data Acquisition Part 7 : Introduction to the Micro- & Nanomechatronic Part 8 : Introduction to the Biomechatronic 1.The Mechatronics Handbook (CRC Press, 2002)
Part 1 General System Description - Survey: Properties of Conventional & Mechatronic Design Systems: Division of Functions between Mechanics and Electronics Improvement of Operating Properties Addition of New Functions General Scheme of a Classical Mechanical-Electronic system Ways of Integration: What is the Mechatronics?: Integration of Components (Hardware) Imbedding the sensors, actuators, microprocessors into the mechanical process Integration of Information Processing (Software) Based on advanced control functions: feed-forward, feedback controls, advanced control systems (fuzzy, soft computing), online information processing. Based on Yasakawa Electronic Company, the Mechatronics is defined by this definition: The word mechatronics is composed of MECHA-, from mechanism and the -TRONICS-, from electronics. In other words, technologies and developed products will be incorporating electronics more and more into mechanisms. 1996, Harashima, Fuada, Tomizuka: Mechatronics is the synergistic integration of mechanical engineering with electronics and intelligent computer control 1997, Shetty, Kolk: Mechatronics is a methodology used for the optimal design of electromechanical products. W. Bolton: Mechatronics, not just a marriage of electrical and mechanical systems and is more than just a control system, it is a complete integration of all of them.
Historical evolution: Historical evolution summing up: At the beginning Mechanics Electronics 1 1 Mechatronics Before Y2K After Y2K The Key Elements of Mechatronics Detailed Key Elements: Based on these historical definitions, the key elements of mechatronics can be following: Physical System Modeling Sensors and Actuators Signals and Systems Computers and Logic Systems Software and Data Acquisition Sensors & Actuators Software & Data Acquisition System modelling MECHATRONICS Signals & Systems Computers & Logic Systems
Definition after Y2K: Based on: Masayoshi Tomizuka (University of California, Berkeley) Mechatronic Systems: And Fundamental Theories: Mechatronic Systems The MECHARONICS: Is a synergetic integration of physical systems with information technology and complex-decision making (in the design, manufacturing and operation of industrial products and processes) Conventional Mechatronic Systems Fundamental Theories: Classical mechanics Electromagnetism Electronics Micro-mechatronic Systems (MEMS) Nano-mechatronic Systems (NEMS) Fundamental Theories: Quantum Theory Nano-electromechanics Bio-mechatronic Systems (BEMS) Fundamental Theories: Anatomy Micro- or/and Nanoelectromechanics Conventional Mechatronic Systems Survey In Vehicle Engineering ~1960s Mechanical actuators, bumpers, switches (no mechatronic system introduced) Conventional Mechatronic Systems-1a: Using a millimeter wave radar system to distance and velocity measuring and to autonomously keeping the desired distance between vehicles. ~1970s Electronic ignition system (1 st mechatronic system at the vehicles) Consist of a crankshaft position sensor, camshaft position sensor, airflow rate, throttle position, rate of throttle position change sensor, and at the end a dedicated microcontroller determining the timing of the spark plug firings. ~1978s ABS (Antilock Brake System) sensing lockup of any of the wheels and then modulating the hydraulic pressure as needed to minimize or eliminate sliding. ~1995s TCS (Traction Control System) sensing slippage during acceleration and then modulating the power to the slipping wheel. 2000< - New applications of mechatronic systems in the automotive world include semi-autonomous to fully autonomous automobiles, safety enhancements, emission reduction, intelligent cruise control (GPS navigation systems), etc. Millimeter wave radar technology has recently found applications, too.
Conventional Mechatronic Systems-1b: Autonomous vehicle system design with sensors and actuators. Conventional Mechatronic Systems-2: Airplane Flight Control System Basic control units of the airplane Proposed diagram involves differential global positioning system (DGPS), real-time image processing and dynamic path planning. Conventional Mechatronic Systems-2: Airplane Flight Control System An example about: How the Control Engineering is involved into mechatronics Closed-loop functional diagram of electromechanical systems within a flight control system: Flight actuators are displaced on control surfaces, and actuators are controlled by digital controllers. Control of aircraft is accomplished by the flight management system. Mechatronic Systems Interfacing & Control Systems An overview of the Interface and the Control Systems of a Mechatronic System Interfacing: Control Systems: Input signals Microprocessor Control Output signals PID Control Actuator output PLC Controllers Signal conditioning Microprocessors Sampling rate µprocessor numerical control Filtering Fixed-point mathematics Data acquisition boards (DAQ) Calibrations µprocessor input-output control Polling & Interrupts I/O transmission µcontroller network systems
Mechatronic Systems Interfacing This section can be enumerated into the Part 4: Systems & Controls (because of: Signals & Systems can be found), and Part 6: Software & Data Acquisition (because of: Sampling & Rating can be found) Interfacing is connection of the mechatronic system with the environment. We can distinguish system input interface and system output interface. Usually the input interface changing some physical quantities to the electrical one, while the output interface convert the electrical signals to some physical one. Mechatronic Systems Interfacing Signal Classification Signals are broadly classified as either continuous-time (CT) or discrete-time (DT) signals, and each of these may in turn be categorized as deterministic or random (Stochastic) signals. A deterministic signal can always be expressed mathematically, whereas the time of occurrence or value of a random signal cannot be predicted with certainty. A CT signal x(t), has a specified value for every value of time t while a DT signal, x(n), has specified a value only at discrete points, that is, for integer values of n. Closely related to CT and DT signals are analog and digital signals, respectively. Rating, Quantization Sampling Mechatronic Systems Interfacing Input Signals Words TRANSDUCERS/SENSORS are often used synonymously. These are devices that convert energy from one form (physical) to another (electrical) one. The output of a sensor is usually an analogue signal, but some intelligent sensors contains A/D converter on-board of sensor and produce a square wave output in form of digital signals, and what is more, some more intelligent sensors contains TCP/IP interface on-board. Mechatronic Systems Interfacing Input Signals How the signals can distribute some information: The answer is the signal modulation. Some well known signal modulation: frequency modulation, amplitude modulation, PWM. etc.
Mechatronic Systems Interfacing Input Signals At the input signals usually some A/D conversion is performed. These devices convert the analogue signals to the digital one. It is several methods for A/D conversion, like successive approximation 10bit motorola converter (SAR). Binary value 0000 0000 0000 0001 1000 0000 1111 1111 Decimal value 0 1 128 255 Voltage 0.0 0.00390625 6.0 11.953125 As an example, let we consider an A/D converter that is converting a voltage level ranging 0 12 V into a single byte of 8 bits. In this example, each binary count increment reflects an increase in analog voltage of 1/256 of the maximum 12 V. There is an unusual twist to this conversion, however. Since a zero value represents 0 [V], and a 128 value represents half of the maximum value, 6[V] in this example, the maximum decimal value of 255 represents 255/256 of the maximum voltage value, or 11.953125 [V]. Mechatronic Systems Interfacing Output Signals The output command from the microcontroller is a binary value in bit, byte (8 bits), or word (16 bits) form. This digital signal is converted to analog using a digitalto-analog converter, or D/A. Let us examine converting an 8-bit value into a voltage level between 0 and 12 V. The most significant bit in the binary value to be converted (decimal 128) creates an analog value equal to half of the maximum output, or 6 [V]. The next digit produces an additional one fourth, or 3 [V], the next an additional one eighth, and so forth. The sum of all these weighted output values represents the appropriate analog voltage. As was mentioned in a previous section, the maximum voltage value in the range is not obtainable, as the largest value generated is 255/256 of 12 [V], or 11.953125[V]. The smoothness of the signal representation depends on the number of bits accepted by the D/A and the range of the output required. The figure demonstrates a simplified step function using a one-byte binary input and 12-V analog output. Mechatronic Systems Interfacing Actuators The output signals are usually received by some kind of ACTUATORS. Actuators are devices that convert energy from one form (electrical) to another (physical) one. The three common actuators are: switches, solenoids, motors. Switches are simple state devices that control some activity, like turning on and off the furnace in a house. Types of switches include relays and solid-state devices. Solid-state devices include diodes, thyristors, bipolar transistors, field-effect transistors (FETs), and metal-oxide field-effect transistors (MOSFETs). A switch can also be used with a sensor, thus turning on or off the entire sensor, or a particular feature of a sensor. Solenoids are devices containing a movable iron core that is activated by a current flow. The movement of this core can then control some form of hydraulic or pneumatic flow. Applications are many, including braking systems and industrial production of fluids. Motors are the last type of actuator. There are three main types: direct current (DC), alternating current (AC), and stepper motors. DC motors may be controlled by a fixed DC voltage or by pulse width modulation (PWM). In a PWM signal, a voltage is alternately turned on and off while changing (modulating) the width of the on-time signal, or duty cycle. AC motors are generally cheaper than DC motors, but require variable frequency drive to control the rotational speed. Stepper motors move by rotating a certain number of degrees in response to an input pulse. Mechatronic Systems Interfacing Signal Conditioning SAMPLING RATE: The rate at which data samples are taken obviously affects the speed at which the mechatronic system can detect a change in situation. For example, the response of a sensor may be limited in time or range. There is also the time required to convert the signal into a form usable by the microprocessor, the A/D conversion time. For voice digitalization, there is a very well-known sampling rate of 8000 samples per second. This is a result of the Nyquist theorem, which states that the sampling rate, to be accurate, must be at least twice the maximum frequency being measured. The 8000 samples per second rate thus works well for converting human voice over an analog telephone system where the highest frequency is approximately 3400 Hz. Lastly, the clock speed of the microprocessor must also be considered. If the ADC and DAC are on the same board as the microprocessor, they will often share a common clock. The microprocessor clock, however, may be too fast for the ADC and DAC. In this case, a prescaler is used to divide the clock frequency to a level usable by the ADC and DAC. FILTERING: Filtering is the attenuation (lessening) of certain frequencies from a signal. This process can remove noise from a signal and condition the line for better data transmission. Filters can be divided into analog and digital types, the analog filters being further divided into passive and active types. Analog passive filters use resistors, capacitors, and inductors. Analog active filters typically use operational amplifiers with resistors and capacitors. Digital filters may be implemented with software and/or hardware. The software component gives digital filters the feature of being easier to change. Digital filters are explained fully in Chapter 29. Filters may also be differentiated by the type of frequencies they affect. 1. Low-pass filters allow lower set of frequencies to pass through, while high frequencies are attenuated. 2. High-pass filters, the opposite of low-pass, filter a lower frequency band while allowing higher frequencies to pass. 3. Band-pass filters allow a particular range of frequencies to pass; all others are attenuated. 4. Band-stop filters stop a particular range of frequencies while all others are allowed to pass.
Mechatronic Systems Control Systems Characterization of the Control Systems This section can be found in the Part 4: Systems & Controls (because of: Hardware & Software Control elements are enumerated here) Hardware Control: Microprocessor Control PID Control PLC Controllers µprocessors µp Numerical & I/O Control Digital Logics (PAL,PLA, GAL, FPGA, CPLD) Signal conditioning Sampling rate Filtering Software Control: System, Software Engineering Software design Testing Data verification & validation Debuggers Logic Analyzer Output part Data acquisition boards (DAQ) Input part