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English for Mechatronics Engineering Page 1 TABLE OF CONTENTS TABLE OF CONTENTS 1 PART 1: DIGITAL LOGIC 3 CHAPTER 1: INTRODUCTION 3 LOGIC GATES 3 CHAPTER 2: APPLICATIONS OF LOGIC GATES 8 INTEGRATED CIRCUIT 8 APPLICATIONS 8 CHAPTER 3: BASIC ELECTRONIC COMPONENTS 10 RESISTANCE 10 CAPACITOR 11 DIODE 13 LIGHT EMITTING DIODE 15 BIPOLAR JUNCTION TRANSISTOR (BJT) 18 CHAPTER 4: MICROCONTROLLER 20 INTRODUCTION 20 IMPORTANT FEATURES 21 POWER SUPPLY CIRCUIT 22 HOW TO START WORKING? 23 PART 2: MECHANICAL ACTUATION SYSTEMS 26 CHAPTER 1: INTRODUCTION 26 MECHANISMS 26 TYPES OF MOTION 27 DEGREE OF FREEDOM 27 CHAPTER 2: CAMS 29 ECCENTRIC CAM 29 English for Mechatronics Engineering Page 2 DROP CAM 31 FLAT CAM 32 CHAPTER 3: GEARS 34 SPUR GEAR 35 HELICAL GEAR 36 DOUBLE HELICAL GEAR 37 BEVEL GEAR 38 WORM GEAR 39 RACK AND PINION 41 GEAR TRAIN 42 CHAPTER 4: BELT AND CHAIN DRIVES 44 PROS AND CONS 44 FLAT BELTS 45 ROUND BELTS 46 VEE BELTS 47 TIMING BELTS 48 CHAIN DRIVE 49 CHAINS VERSUS BELTS 50 CHAPTER 5: BEARINGS 51 DEEP-GROOVE 52 FILLING - SLOT 53 ANGULAR CONTACT 54 DOUBLE-ROW 55 SELF-ALIGNING 56 STRAIGHT-ROLLER BEARING 58 TAPER ROLLER 59 NEEDLE ROLLER 61 English for Mechatronics Engineering Page 3 PART 1: DIGITAL LOGIC CHAPTER 1: INTRODUCTION Many control systems are concerned with setting events in motion or stopping them when certain conditions are met. For example, with domestic washing machine, the heater is only switched on when there is water in the drum and it is to the prescribed level. Such control involves digital signals where there are only two possible signal levels. Digital circuitry is the basis of digital computers and microprocessor controlled systems. There are two input signals which are either 1 or 0 signals and an output signal which is 1 or 0 signal. The controller is here programmed to only give a 1 output if both the input signals are 1. Such an operation is said to be controlled by a logic gate .Logic gate is the basic building blocks for digital electronic circuits. The term combinational logic is used for the combining of two or more basic logic gates to form a required function. LOGIC GATES Logic gates are the basic components in digital electronics. They are used to create digital circuits and even complex integrated circuits. For example, complex integrated circuits may bring already a complete circuit ready to be used – microprocessors and microcontrollers are the best example – but inside them they were projected using several logic gates. In this tutorial we will teach you everything you need to know about logic gates, with several examples. As you may already know, digital electronics accept only two numbers, “0” and “1.” Zero means a 0 V voltage, while “1” means 5 V or 3.3 V on newer integrated circuits. You can think “0” and “1” as a light bulb turned off or on or as a switch turned off or on. a. AND gate: Suppose we have a gate giving a high output only when both input A and input B are high; for all other conditions it gives a low output. This is an AND logic gate. We can visualize the AND gate as an electric circuit involving two switches in series. Only when switch A and B are closed, there is a current. English for Mechatronics Engineering Page 4 (a) Represented by switches (b) Symbols The relationship between the inputs and the outputs of an AND gate can be expressed in the form of an equation, called Boolean equation. The Boolean equation for the AND gate is written as A . B = Y An example is a burglar alarm in which it gives an output, the alarm sounding, when the alarm is switched on and when a door is opened to active a sensor. The relationships between inputs to a logic gate and the outputs can be tabulated in a form known as truth table. This specifies the relationships between the inputs and outputs. We can write the truth table as A B Output 0 0 0 1 1 0 1 1 b. OR gate: An OR gate with inputs A and B gives an output of a 1 when A or B is 1. We can visualize such a gate as an electric circuit involving two switches in parallel. When switch A or B is closed, then there is a current. OR gates can also have more than inputs. We can write the Boolean equation for an OR gate as: A + B = Y English for Mechatronics Engineering Page 5 (a) Represented by switches (b) Symbols A B Output 0 0 0 1 1 0 1 1 c. NOT gate: a NOT gate has just one input and one output, giving a 1 output when the input is 0 and a 0 when input is 1. The NOT gate gives an output which is the inversion of the input and is called an inverter. The 1 representing NOT actually symbolizes logic identity, i.e. no operation, and the inversion is depicted by the circle on the output. Thus, if we have a digital input which varies with time, the output variation with time is the inverse. The Boolean equation describing the NOT gate is A Y A bar over a symbol is used to indicate that the inverse, or complement, is being taken; thus the bar over the A indicates that the output Y is the inverse value of A. d. NAND gate: The NAND gate can be considered as a combination of an AND gate followed by a NOT gate. Thus when input A is 1 and input B is 1, there is an output of 0, all other inputs giving an output of 1. Input Output 1 0 English for Mechatronics Engineering Page 6 The NAND gate is just the AND gate truth table with the outputs inverted. An alternative way of considering the gate is as an AND gate with a NOT gate applied to invert both the inputs before they reach the AND gate. The figure below shows the symbols used for the NAND gate, being the AND symbol followed by the circle to indicate inversion. The Boolean equation describing the NAND gate is: A B Y  The following is the truth table: A B Output 0 0 0 1 1 0 1 1 e. NOR gate: The NOR gate can be considered as a combination of an OR gate followed by a NOT gate. Thus when input A or input B is 1 there is an output of 0. It is just the OR gate with the outputs inverted. An alternative way of considering the gate is as an OR gate with a NOT gate applied to invert both the inputs before they reach the OR gate. The figure below shows the symbols used for the NOR gate; it is the OR symbol followed by the circle to indicate inversion. The Boolean equation for NOR gate is: A B Y  English for Mechatronics Engineering Page 7 The following is the truth table for the NOR gate. A B Output 0 0 0 1 1 0 1 1 f. XOR gate: XOR stands for exclusive OR. XOR gate compares two values and if they are different its output will be “1.” XOR operation is represented by the symbol ⊕. So Y = A ⊕ B is the Boolean equation for the XOR gate. The following is the truth table for the XOR gate. A B Output 0 0 0 1 1 0 1 1 g. XNOR gate: XNOR stands for exclusive NOR and is an XOR gate with its output inverted. So, its output is at “1” when the inputs have the same value and “0” when they are different. XNOR operation is represented by the symbol (·). The Boolean equation for XNOR gate is: A (·) B = Y English for Mechatronics Engineering Page 8 CHAPTER 2: APPLICATIONS OF LOGIC GATES INTEGRATED CIRCUIT Logic gates are available as integrated circuits. The different manufacturers have standardized their numbering schemes so that the basic part numbers are the same regardless of the manufacturer. For example, Fig. 1(a) shows the gate systems available in integrated circuit 7408; it has four two-input AND gates and is supplied in a 14-pin package. Power supply connections are made to pins 7 and 14, these supplying the operating voltage for all four AND gates. In order to indicate at which end of the package pin 1 starts, a notch is cut between pins 1 and 14. Integrated circuit 7411 has three AND gates which each having three inputs; integrated circuit 7421 has two AND gates with each having four inputs. Figure 1(b) shows the gate systems available in integrated circuit 7402. This has four two-input NOR gates in a 14-pin package, power connections being to pins 7 and 14. Integrated circuit 7427 has three gates with each having three inputs. Figure 1: Integrated circuit (a) 7408, (b) 7402 APPLICATIONS 1. Digital comparator A digital comparator is used to compare two digital words to determine if they are exactly equal. The two words are compared bit by bit and a 1 output given if the words are equal. To compare the equality of two bits, an XOR gate can be used; if the bits are both 0 or both 1 the output is 0, and if they are not equal the output is a 1. To obtain a 1 output when the bits are the same we need to add a NOT gate, this combination of XOR and NOT being termed an XNOR gate. To compare each of the pairs of bits in two words we English for Mechatronics Engineering Page 9 need an XNOR gate for each pair. If the pairs are made up of the same bits then the output from each XNOR gate is a 1. We can then use an AND gate to give a 1 output when all the XNOR outputs are ones. Figure 2 shows the system. A3 B3 A2 B2 A1 B1 A0 B0 A = B Figure 2: Comparator 2. Coder The Fig. 3 shows a simple system by which a controller can send a coded digital signal to a set of traffic lights so that the code determines which light, RED, AMBER OR GREEN, will be turned on. To illuminate the RED light we might use the transmitted signal A = B = 0, for the AMBER light A = 0, B = 1 and for the GREEN light A = 1, B = 0. We can switch on the lights using these codes by using three AND gates and two NOT gates. AMBER A RED B GREEN Figure 3: The traffic lights English for Mechatronics Engineering Page 10 CHAPTER 3: BASIC ELECTRONIC COMPONENTS RESISTANCE The electrical resistance of an object is a measure of its opposition to the passage of a steady electric current. An object of uniform cross section will have a resistance proportional to its length and inversely proportional to its cross-sectional area, and proportional to the resistivity of the material. Discovered by Georg Ohm in the late 1820s, electrical resistance shares some conceptual parallels with the mechanical notion of friction. The SI unit of electrical resistance is the ohm, symbol Ω. Resistance's reciprocal quantity is electrical conductance measured in Siemens, symbol S. The resistance of a resistive object determines the amount of current through the object for a given potential difference across the object, in accordance with Ohm’s laws: V I R  where R is the resistance of the object, measured in ohms, equivalent to J·s/C 2 V is the potential difference across the object, measured in volts I is the current through the object, measured in amperes We all know that voltmeter and ammeter are used for measuring the voltage and the current respectively. For the resistance, the meters that use to measure it is the ohmmeter. But what if we don't have an ohmmeter to use? Color coding system for resistors consists of three colors to indicate the resistance value in ohms of a certain resistor, sometimes the fourth color indicate the tolerance value of the resistor. By reading the color coded in correct order and substituting the correct value of each corresponding color coded as shown in the table below, you can immediately tell all you need to know about the resistor. Each color band represents a number and the order of the color band will represent a number value. The first 2 color bands indicate a number. The 3 rd color band indicates the multiplier or in other words the number of zeros. The fourth band indicates the tolerance of the resistor. In most cases, there are 4 color bands. However, certain precision resistors have 5 bands or have the values written on them, refining the tolerance value even more.