Download Chapter 1: Overview of Mechatronics Systems Engineering

Chapter 1: Overview of Mechatronics Systems Engineering
1. What is Mechatronics?
Mechatronics = Mecha(nical) + (Elec)tronics
The term “Mechatronics” came from Japan in late 1960s, spread through Europe, and is growing in USA.
Nanotronics, etc.
Major Conferences:
IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM) (odd year)
Mechatronics Forum International Conference (Mechatronics 2006)
ASME/IEEE International Federation of Automation Control (IFAC) (even year)
Mechatronics is the synergistic integration of mechanical engineering with electronics and intelligent
computer control in the design and manufacture of products and processes.
Mechanical Device + control unit + preprogramming code
Mechatronics is a truly multidisciplinary approach to engineering. New products and systems based on
the integrated application of mechanical, electronic and computing engineering technologies are
demonstrating reduced mechanical complexity, increased performance, and often, previously impossible
capabilities.
2. A typical mechatronic system includes:
1.
2.
3.
4.
5.
6.
mechanical device
analog circuits
digital circuit
microprocessor/microcomputer/microcontroller
sensors
actuators
Nearly everyone who has taught, or taken, an engineering course on the subject of Mechatronics quickly
comes to the same conclusion: the design and implementation of mechatronic systems is a highly
satisfying process in which practitioners balance analytical skills with craftsmanship and creativity. The
vast majority of Mechatronics courses are offered through ME Departments around the world. National
survey
Dr. Winncy Du, E310F, MAE Dept., SJSU, Tel.:408-924-3866,E-mail: [email protected]
Course Web: www.engr.sjsu.edu/wdu/ME285Spring2006
3. The typical fundamental Mechatronics course covers :
(4) Plant
+
Ideal
Performance
D/A
Controller
-
(6,7)
Actual
Performance
Actuator
(8)
(10)
A/D
Amplifier
(8)
(5)
Actual
Output
Sensor
(9)
Analog/Real World (Analog Circuit) (2)
Digital World (Digital Circuit) (3, 6)
Figure 1 The whole picture of a typical fundamental Mechatronics class
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
Chapter 2: Electric Circuits and Components
Chapter 3: Semiconductor Electronics
Chapter 4: System Response
Chapter 5: Analog Signal Processing Using Operational Amplifiers
Chapter 6: Digital Circuits
Chapter 7: Microcontroller Programming and Interfacing
Chapter 8: Data Acquisition
Chapter 9: Sensors
Chapter 10: Actuators
HW#0: Give me your email address by sending an email to me.
(1) Basic Passive Electrical Components:
All DC and AC circuits may contain the three basic passive electrical elements1: resistor, capacitor,
and inductor.
1) Resistor: a dissipative element that converts electrical energy into heat (unit: Ω - Ohm).
Related law -- Ohm’s Law:
For an ideal resistor: V = IR
Resistors in series: Req =
Ri
Resistors in parallel:
Application: in a circuit, a resistor is used as a
1
=
Req
R1
1
Ri
R2
Vout
Vin
An active component/element means that the component has to have its own power supply for operation. Since a
resistor, a capacitor, and an inductor don’t need their own power supply for their function, they are all called
“passive electrical components”.
1
Dr. Winncy Du, E310F, MAE Dept., SJSU, Tel.:408-924-3866,E-mail: [email protected]
Course Web: www.engr.sjsu.edu/wdu/ME285Spring2006
Vout =
Voltage Divider:
R2
Vin
R1 + R2
e.g. if you need 6V for your load, but only 12V voltage source is available, then you need two
resistors in series to get the 6V.
I out
Current Divider:
R1
=
I in
R1 + R2
Iin
R1
R2
Iout
e.g. if you need 15 mA for your load, but only 0.1A current source is available, then you need
two resistors in parallel to get the 15 mA.
Types of Resistors:
Potentiometer: Variable resistors, screw, knob, or linear slide –
A potentiometer that is included in a circuit to adjust (trim) the resistance in the circuit is
called a trim pot.
Wire-lead Resistor: we will use this type of resistors a lot in this class. Please read Page 11 –
12 in the textbook to see how to find a resistor’s value and precision based on its color bands.
Surface Mount Resistor: this type of resistors is used a lot in the Mother/Main board of a
computer, or other commercial boards.
Others: single in-line package, dual in-line package (see figure 2.6 on page 11).
2) Capacitor: a passive element that stores energy in the form of an electric field (Unit. F, farads).
Note: F is a very big unit, the capacitance range we usually use is 1 pF ~ 1000 µF.
The voltage-current relationship of a capacitor is:
1
dV (t )
I (t )dt
( or I (t ) = C
)
C
dt
1
1
Capacitors in series:
=
Capacitors in parallel: Ceq =
Ceq
Ci
V (t ) =
Ci
Application: a capacitor is used to
(1) store electrical energy
(2) protect your circuit or important components
For a capacitor, the voltage is the integration of the current with time, that means that it
will take TIME for the voltage to reach to certain level. If by accident you put too much
power in the circuit, the circuit or the components will not be burned immediately due to
the capacitor. It is a good exercise to put a capacitor in parallel to the component that you
don’t want to damage.
Types of Capacitors:
Dr. Winncy Du, E310F, MAE Dept., SJSU, Tel.:408-924-3866,E-mail: [email protected]
Course Web: www.engr.sjsu.edu/wdu/ME285Spring2006
Film Capacitors: A relatively large family of capacitors, they differ pretty much just in their
dielectric properties. Available capacitance ranges from 10pF - 15uF. Members include
polyester, polystyrene, polypropylene, polycarbonate, metallized paper, etc.
Ceramic Capacitors: The common form is the multi-layer or stacked ceramic (monolithic);
single layer also exists (ceramic disk). Physically, the multi-layer looks like the film and foil
above, a dielectric stuffed between metal plates. The multi-layer is marginally more expensive
than the single layer.
Silver-mica: Another stacked capacitor. Mica is really the general family name (mica is the
dielectric); silvered mica is just the most popular form. They are popular for their high
frequency characteristics (up to 500MHz). Typical values range from 2pF to 1500pF.
Electrolytics: A "breakthrough" in capacitor technology in the early 1900'
s. Instead of placing
a solid wedge of something (which can be quite thin), an electrolyte solution is used. The
electrolyte serves as the 2nd electrode. The electrolyte is not the dielectric. The dielectric is a
very thin layer of oxide which is grown electro-chemically in production. The thickness of this
oxide layer is on the order of .01µm, much smaller than any piece of plastic or ceramic that
could be used as a separator.
Others: Surface Mount Capacitors, etc.
Important Parameters to consider and Choose a Capacitor:
Capacitance
ESR (power dissipation in the capacitor and useful frequency range)
Tolerance (ability to plug it into frequency sensitive circuits)
Temperature/Aging Drift (capacitance changes in sensitive circuits)
ESL (useful frequency range)
3) Inductor: an energy storage element that stores energy in the form of a magnetic field (Unit:
Henry H, typical 1uH ~ 0.1H).
The voltage-current relationship of an inductor is:
V (t ) = L
Inductors in series: Leq =
dI (t )
dt
Li
Inductors in parallel:
1
=
Leq
1
Li
Application: Usage of Inductor
(1) Store magnetic energy
(2) Electric motor – large inductance
(3) Transformer
Types of Inductors:
i.
Radial inductor
ii.
Chip Inductor
iii.
Power Inductor
Dr. Winncy Du, E310F, MAE Dept., SJSU, Tel.:408-924-3866,E-mail: [email protected]
Course Web: www.engr.sjsu.edu/wdu/ME285Spring2006
(2) Basic Semiconductor Electronics Components:
(1) Diodes
Diodes allow electricity to flow in only one direction. The arrow of the circuit symbol shows the
direction in which the current can flow. Diodes are the electrical version of a valve and early Diodes were
actually called valves.
There are several types of semiconductor junction diodes:
Diode
(0.7V)
Light-Emitting
Diode (LED)
(1.5-2.5V)
Zener
Diode
Schottky
Diode
Fig. Some Diode Symbols
LED (Light-Emitting Diode): emits photons when forward biased. A LED has a voltage drop of
1.5~2.5V.
Photodiodes: When light hits on the diode, there is a current goes through (reverse current)
Zener Diode (Voltage regulator diode): can maintain a nearly constant voltage over a wide range of
currents (or loads). Zener diode should be reverse biased with a voltage.
Schottky Diode: (named after German physicist Walter H. Schottky) is a semiconductor diode with a low
forward voltage drop and a very fast switching action. A typical application is discharge-protection for
solar cells connected to lead-acid batteries. While standard silicon diodes have a forward voltage drop of
about 0.6 V, Schottky diodes have a drop of only about 0.3 V. This is due to the higher current density in
the Schottky diode.
A Schottky diode uses a metal-semiconductor junction as a Schottky barrier (instead of a semiconductorsemiconductor junction as in conventional diodes). This Schottky barrier results in both very fast
switching times and low forward voltage drop.
It is often said that the Schottky diode is a "majority carrier" semiconductor device. This means that if the
semiconductor body is doped N-type, only the N-type carriers (mobile electrons) play a significant role in
normal operation of the device. No slow, random recombination of N- and P- type carriers is involved, so
this diode can cease conduction faster than an ordinary PN rectifier diode. This property in turn allows a
smaller device area, which also makes for a faster transition. Therefore broad-area Schottky diodes are
useful in switch-mode power converters which operate at frequencies approaching 1 MHz. Small-area
Schottky diodes are the heart of RF detectors and mixers, which often operate up to 5 GHz.
The most evident limitation of the Schottky diode is difficulty reaching high reverse-bias voltage ratings,
and relatively high series resistance when high voltage ratings are attempted. Relatively high reverse
leakage current may present an issue in some applications.
Commonly used Schottky diodes: 1N5817, and Schottky metal-semiconductor junctions are featured in
7400 series logic devices because of their higher switching speeds and lower voltage drops.
Dr. Winncy Du, E310F, MAE Dept., SJSU, Tel.:408-924-3866,E-mail: [email protected]
Course Web: www.engr.sjsu.edu/wdu/ME285Spring2006
(2) Transistors (BJT Transistor, Field-Effect Transistors)
Transistor is one of the most important components in Mechatronics and Automation – without a
transistor, it is impossible to realize control.
Bipolar Junction Transistor (BJT): A BJT has two PN junctions: one BE (Base-Emitter junction)
functions as a forward biased diode; the other functions as a reverse biased diode (Base-Collector
Junction) BECAUSE. Thus, the voltage across CE, i.e., Vce must be high.
Field-Effect Transistor:
Dr. Winncy Du, E310F, MAE Dept., SJSU, Tel.:408-924-3866,E-mail: [email protected]
Course Web: www.engr.sjsu.edu/wdu/ME285Spring2006