2. Embedded Systems
Microprocessor based systems designed to
control a range of functions
BUT
Not designed to be programmed by the end
user.
Examples: Washing mashines, DVD players,
Photo-copying machines, camcorders.
Ref: Mechatronics : Bradley,
Dawson, Burd, Loader
3. Control
1. Program Control
In mechatronic systems the system functions can be
redefined easily using software. This can be done by
a. the user selecting from a number of predefined and
previously stored programs
b. loading a new program from an external source
e.g. Automated Manufacturing Cell, Automatic Sewing
Machine
Ref: Mechatronics : Bradley,
Dawson, Burd, Loader
4. Control
2. Adaptive Control
Local processing power is available due to embedded
μC. This enables variation of the programmed path /
speed / setting according to the local conditions in
order to optimise the behaviour of system.
E.g. Active suspension system, CNC machines
Ref: Mechatronics :
Bradley, Dawson, Burd,
5. Control
3. Distributed Systems
The mechatronic devices are arranged so
that they work in parallel, i.e. simultaneously,
they can be distributed over a large area and
be synchronised with the help of μP.
E.g. Active suspensions, Conveyor systems
Ref: Mechatronics :
Bradley, Dawson, Burd,
6. The design process can be split into several stages,
each separated by a review and a
continue/rework/abort point.
a. Need
b. Feasibility
c. Specification
d. Conceptual Design
e. Analysis and Modelling
f. Embodiment and
Optimisation
g. Detail Design
Ref: Mechatronics : Bradley, Dawson, Burd,
Loader
Design Process
7. Types of Design
• Design for function
• Design for strength or stiffness
• Design for reliability
• Design for maintainability
• Design for manufacture
Ref: Mechatronics : Bradley, Dawson, Burd,
Loader
8. Mechanisms
• Mechatronic systems require mechanisms for
various functions like
– Change of speed
– Action at a distance
– Force amplification
– Sequencing
– synchronising
Ref: Mechatronics : Bradley, Dawson, Burd,
Loader
9. Mechanisms – Load conditions
• A mechanism experiences variety of load
conditions at both input and output.
• It has its own inertia due to its motion
• The mechanism driver must be able to provide
sufficient force as well as torque to cover the
entire operational envelope
Ref: Mechatronics : Bradley, Dawson, Burd,
Loader
10. Structures – Load Conditions
• The loading on a structure must be carefully analysed
before designing adequate structure.
• The stresses may be difficult to analyse.
• Analysis by computer modelling is helpful.
TYPES :
* static loading
* dynamic and cyclic loading
* impulse and shock loading
Ref: Mechatronics : Bradley, Dawson, Burd,
Loader
11. Mechanisms – Load conditions
Load Conditions decide
actuator requirements
attaining partial static balance
articulation requirements
speed and accuracy
minimization of kinetic energy
power transmission over a distance
effect of assembly play and friction
inertia
Ref: Mechatronics : Bradley, Dawson, Burd,
Loader
12. Mechanism - Flexibility
• Resilience – each member of mechanism
experiences tension, bending and torsion.
Allowed loading can be determined by
mathematical modelling
• Backlash – flexibility in mechanism causes
backlash in gears or play in joints
• Vibration – flexibility in mechanism leads to
vibrations in dynamic loading.
Ref: Mechatronics : Bradley, Dawson, Burd,
Loader
13. Flexibility of Structures
• Using microprocessors, local flexibility in
structures can be taken care of, if we use
closed loop control with feedback sensor close
to point of action
• If sensors are located far away from the point
of action then errors can result due to
flexibility of structure. So the structure will
have to be designed to be very stiff. (making it
heavy, increasing energy requirements of
robot)
Ref: Mechatronics : Bradley, Dawson, Burd,
Loader
14. Flexibility of Structures
• Vibration Effects - Flexible structures are
prone to vibrations, particularly if excited at
natural frequencies.
• Materials – suitable choice of material and
manufactured form can greatly affect the
flexibility and life of structure.
Ref: Mechatronics : Bradley, Dawson, Burd,
Loader
15. Man-Machine Interface
• Facility by which bidirectional transfer of
information required for system operation
takes place
• It is concerned with ergonomic aspects of the
design and covers areas such as display of
information, operator systems, environmental
factors and safety.
Ref: Mechatronics : Bradley, Dawson, Burd,
Loader
17. • Level 0 contains the field devices such as flow and temperature sensors, and final
control elements, such as control valves
• Level 1 contains the industrialised Input/Output (I/O) modules, and their
associated distributed electronic processors.
• Level 2 contains the supervisory computers, which collect information from
processor nodes on the system, and provide the operator control screens.
• Level 3 is the production control level, which does not directly control the process,
but is concerned with monitoring production and monitoring targets
• Level 4 is the production scheduling level.
• Levels 1 and 2 are the functional levels of a traditional DCS, in which all equipment
are part of an integrated system from a single manufacturer.
• Levels 3 and 4 are not strictly process control in the traditional sense, but where
production control and scheduling takes place.
12/07/17
Ref: Mechatronics :
Bradley, Dawson, Burd,
