Al-Azhar University
Faculty of Engineering & Information Technology
Mechatronic Design
(ITME4333)
Chapter 1 :
Introduction in Mechatronic Design
Prepared by Dr. Alaa AbuZaiter
First Semester, 2020/2021
What is Mechatronic ?
■ Mechatronics is a multidisciplinary field of engineering that includes a
combination of mechanical engineering, robotics, electronics,
computer engineering, telecommunications engineering, systems
engineering and control engineering.
■ As technology advances, the subfields of engineering multiply and
adapt. Mechatronics' aim is a design process that combines these
subfields.
■ Originally, mechatronics just included the combination of mechanics
and electronics, therefore the word is a combination of mechanics and
electronics; however, as technical systems have become more and
more complex the definition has been broadened to include more
technical areas.
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Mechatronics Systems
Computers
Cars
Tools
Consumer
Electronics
Stealth Bomber
High Speed Trains
MEMS
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What is Mechatronic design ?
■ Mechatronic design is the integrated design of a mechanical
system and its embedded control system. In order to make
proper choices early in the design stage, tools are required that
support modelling and simulation of physical systems together
with the controllers with parameters that are directly related to
the real-world system.
■ Such software tools are becoming available now. Components in
various physical domains (e.g. mechanical or electrical) can
easily be selected from a library and combined into a ‘process’
that can be controlled by block-diagram-based (digital)
controllers.
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Components of a Mechatronic
System
There are basically four main components of any
mechatronic system. Some mechatronic systems might
contain some other components, but these four are
essential for the successful operation of a mechatronic
system:
1. The physical system being controlled (mechanical,
fluidic, chemical, thermal, and electrical).
2. Actuator: The actuator provides the force or torque (or
other relevant physical input) to the physical system to
be controlled. In mechanical systems, the actuator
could be either translational (usually referred to as
linear) or rotational.
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Components of a Mechatronic
System
3. Sensors. Sensors are the eyes and ears of the
controller. Sensors are also referred to as transducers
(although strictly speaking there are subtle differences
between sensors and transducers).
4. Controller: The controller is the brain of the
mechatronic system. It reads the input signals
representing the state of the system; compares them to
the required states; and outputs signals to the actuators
to control the physical system.
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The following are examples of
mechatronic systems:
■ Home applications (e.g., washing machines). Many of the
home applications that are in use today are mechatronic
systems. They are manufactured in large numbers of
masse and typically require small controllers to be
“embedded” within them.
■ ABS (anti-lock braking system) and many areas in
automotive engineering. An anti-lock braking system on
a vehicle is a system that prevents the wheels from
ceasing up or stopping to rotate when the brakes are
suddenly pressed.
■ Sorting and packaging systems in production lines.
Mechatronic systems are effectively the basis for
modern factory automation.
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■ Mobile robots and manipulator arms. Robots are widely used today in
all spheres of life. Robots are generally used for applications that are
inaccessible (difficult locations to get to due to height or space), dull
(repetitive and tedious tasks) or dangerous (hazardous environments).
■ Computer Numerically Control production machines (CNC). CNC
machines are critical in modern manufacturing systems. They allow the
user to produce a product directly from a computer model of the piece.
■ Aeroplanes and helicopters: These are complex examples of
mechatronic systems that incorporate hundreds or even thousands of
smaller sub-mechatronic systems.
■ Tank fluid level and temperature control systems, an example of which
is the process used to produce bio-fuels from vegetable oil.
■ Temperature control system in an industrial oven.
■ Using robots for painting windows and doors
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The Four Questions that Should be Asked
when Designing a Mechatronic System
1- Is system dynamics important?
If the speed of response of a system is critical to its stability and time
response specification (e.g. overshoot, rise time, settling time …), then
system dynamics is important and has to be considered in the design. In
this case, a dynamic model has to be developed for the whole system
(including the plant, controller, actuator and sensor).
The model is then used to design a suitable controller. System
dynamic is usually important if one or both of the following two conditions is
true:
-
The system must respond quickly to change in the reference value to
overcome the effect of disturbances
-
when achieving an accurate and exact value of the controlled
variable(s) is important.
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The following list includes examples of systems for which system
dynamics is critical:
- Quad-rotor
- Vehicle active suspension system
- Space vehicle
On other hand, for the following systems, system dynamics is not
critical:
- eyes scanning system for identification purposes
- Artificial nose
- A solar tracking photo-voltaic system
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The Four Questions that Should be Asked
when Designing a Mechatronic System
2. What type of components to select for each of the
four main components for the mechatronic
system?
The designer of the system will have to make a decision regarding the
components of the mechatronic system, as follows:
a- Control algorithm: example: PI,PD,PID, lead-lag compensator,
Fuzzy controller, neural… genetic, digital PID …
b- Physical controller: This is the physical controller within which the
control algorithm will be implemented. Examples: PLC, PC/laptop, and
microcontrollers, as well as relays and the older type of analogue
computers and logic gates.
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c- Actuator System: The actuator executes the instructions of the
controller to realize changes in the plant. The actuator systems
comprises the following three sub-components: variable speed drive
(optional); actuator (mandatory); mechanical drive (optional).
d- Sensor/Transducer/feedback Drivers): The sensor or feedback
devices are the eyes and ears of the mechatronic system. They can be
thermal, mechanic (translational or rotational) … etc. Where system
dynamics is important, it is necessary to find transfer function of the
sensor as well, as it forms the H(s) transfer function shown in the figure
below.
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The Four Questions that Should be Asked
when Designing a Mechatronic System
3- The size of each component: Once the design has selected the
components to be used he/she has to size them. Calculations have to
be carried out to find the necessary size. This is especially true of the
actuator system (e.g. motor, variable frequency drive, gearbox).
4- Resolution, accuracy and precision: Once the sensor/feedback has been
selected, it is necessary to ensure that it can achieve the required
accuracy, resolution and precision. The user requirements specify the
required accuracy, resolution and precision.
In some cases, the controller selection and the actuator selection have to
be revised or changed in order to achieve these requirements
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Examples of User Requirements
Specifications for a Mechatronic System
■ The following categories include the types of users requirements for
mechatronic systems:
1.
Size/Capacity/Force/Torque/Stroke: This is the most obvious user
requirement. It is related to the size of the system, in relationship to what
is can do. For example, a bottle filling system will be able to fill 1000
bottles per hour; or on elevator can carry eight persons; or a printer can
print 12 pages per minute.
2.
Safety/Reliability/Maintainability/Availability.
3.
System dynamics (e.g. rise time; overshoot; settling time).
4.
Resolution/Accuracy/Precision: These characteristics are related to both
actuator(s) and transducer(s).
Resolution is the smallest change in input that would cause a change in
output.
Accuracy is freedom from systematic errors.
Precision Is freedom from random errors.
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Examples of User Requirements
Specifications for a Mechatronic System
5.
User Friendliness: The system user interface should be user
friendly. It should allow different levels if access. It should also be
“fool proof”.
6.
Energy Consumption: In some application, reducing the amount of
energy consumed must be restricted/reduced.
7.
Cost (Capital cost/Running cost): It is important to consider all
costs associated with the system, throughout the lifetime of the
system. This includes capital costs (initial cost of the system) as
well as running costs (energy costs, maintenance cost).
8.
Space/Size/Weight: In certain cases, there may be constraint on
the size of the system and its weight.
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Examples of User Requirements
Specifications for a Mechatronic
System
9.
Environment: It is important to consider the environment in which
the system will be operated. For example, ambient temperature,
humidity, dust, and foreign particle and fluid ingress.
10. Versatility : A versatile system is one that can be used in different
ways.
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