Download control system application in automobile industries.

OMOTOSO KOLAPO .O.
12/ENG04/052
ASSIGNMENT
CONTROL SYSTEMS APPLICATIONS IN BIOMEDICINE, POWER
INDUSTRIES, AVIATION AND AUTOMOBILE INDUSTRIES.
Definition of Control System
A control system is a system of devices or set of devices, that manages, commands, directs or
regulates the behaviour of other device(s) or system(s) to achieve desire results. In other words, the
definition of control system can be rewritten as A control system is a system, which controls other
system.
As the human civilization is being modernized day by day the demand of automation is increasing
accordingly. Automation highly requires control of devices. In recent years, control systems play
main role in the development and advancement of modern technology and civilization. Practically
every aspect of our day-to-day life is affected less or more by some control system. A bathroom toilet
tank, a refrigerator, an air conditioner, a geezer, an automatic iron, an automobile all are control
system. These systems are also used in industrial process for more output. We find control system in
quality control of products, weapons system, transportation systems, power system, space technology,
robotics and many more. The principles of control theory are applicable to engineering and nonengineering field both.
CONTROL SYSTEM APPLICATION IN AUTOMOBILE INDUSTRIES.
Mechanical systems in automobiles are largely replaced by electronic systems. Today Automobile
industry is making great use of embedded systems. Ranging from wiper controls to complex anti-lock
brake controls and air bags, embedded systems have gained the overall control of recent automobiles.
The automobiles that are built around using microcontrollers, digital signal processors or using both
the processors are commonly called as Electronic Control Units. Today many BMW cars and luxury
vehicles come up with large number of embedded controllers. The first embedded system based
automobiles Volkswagen came in the year 1968.
Some of the current trends of embedded systems in automobiles include airbag controllers, navigation
systems, satellite radio, adaptive cruise control, drive by wire, heads up displays etc.
1. Anti-Lock Braking System
Anti-lock brake system is used in automobiles to avoid the vehicles from skidding especially in a
slippery road. This system allows the wheels of the vehicle to have better contact with the road. This
system basically consists of sensors to track the speed, valves, pump and a controller.
Parts of Anti-lock brake System in Automobiles
Speed Sensors: Helps in knowing the deceleration and acceleration of a vehicle.
Valves: At the brake line of the brakes in the vehicle there are valves. The valves are placed in 3
positions. At the first position, the valve is kept open to pass the pressure from the master cylinder to
the brake. In the second position, the valve is kept in the closed position, so that more pressure does
not reach and the driver does not need to pull the brake pedal harder. And finally in the position three,
the pressure from the brake is released through this valve.
Pump: Gives back the pressure to the brake when valve is released.
Controller: Known as Controller Anti-Lock Brake monitors the sensors and the valves.
Working of Anti-lock brake system in Automobiles
There is an electronic control unit in the system which monitors the movement of the wheel. If a
wheel in the automobiles goes slow, the speed sensors will tell the valves to reduce pressure to the
brake and thereby the wheel turns faster. On the other hand, if the wheel goes faster, the pressure to
the wheel is increased thereby slowing down the wheel.
2. Satellite Radio
Satellite radio is a radio service broadcast from satellites to automobiles. It is available by
subscription and it is commercial free.
3. Navigation Systems
Navigation systems in automobiles are gaining wide popularity. These systems are made up with
different functions that can help a common man. These systems get the signals coming from the
satellites and allow knowing the position and direction of the vehicle. This system basically consists
of:
GPS receiver and antenna.
Sensor
Screen
Map database
Navigation computer
Global Positioning System (GPS) Antenna and receiver is used to get the information from the
satellites and to know the position of the vehicle. Sensor used is basically of two types. They are
speed and direction sensors. Speed Sensors allows knowing the travelling distance of the vehicle.
While the direction sensor keeps on detecting the direction of vehicle. This system uses a screen for
display purposes. Computer helps in checking the information from antenna, sensors with the map
database and displays on the screen with the help of a circuitry.
4. Drive by Wire
This system helps to replace the mechanical systems in automobiles with electronic systems using
actuators and HMI (human machine interfaces). Components of the automobiles like belts, steering
column, pumps, coolers, vacuum servos and master cylinders, hoses, intermediate shafts are
eliminated.
5. Adaptive Cruise Control
Embedded System in Automobiles has made the driverless car a big reality. “Google Driverless car is
an example”. Adaptive cruise control is now widely used in automobiles to make a minimum distance
between vehicles on high traffic highways and in areas of busy traffic. When the traffic congestion
goes down, adaptive cruise control helps to change the speed of the vehicle using the braking system
Each automobiles having the adaptive cruise control will be having radar as a transceiver fixed on it to
know the distance and speed of the vehicles in the path. The computer associated with the ACC unit
helps to control brake and throttle of the automobiles.
6. Airbag control system in Automobiles
Airbags are generally designed to inflate in the cases of frontal impacts in automobiles. When the
collision process happens, an electric current is sent to the ignition system. This electric current keeps
on heating the filament and thereby ignites the capsule which in turn ignites the pellets and generate
the gas. When the gas expands, the air bags also get inflated. All this happens within a time limit of
0.1 sec.
Embedded Systems in Automobiles - Airbag Control System
Major Industries That Help Automobile Industry
Some of the major industries that help to develop these current trends in automobile industry are:
Atmel: Provides different controllers like ARM, 8051. Most of the body electronics, security, safety
and automotive products are manufactured by them.
Texas Instruments: They provide different controllers, automotive control chips and DSPs to
automobile industry.
Xilinx: Provides different CPLDs, FPGAs, and other application related cores for development of
navigation systems, adaptive cruise control etc.
CONTROL APPLICATIONS OF SYSTEMS IN AVIATION
A control system is a collection of mechanical and electronic equipment that allows an aircraft to be
flown with exceptional precision and reliability. A control system consists of cockpit controls,
sensors, actuators (hydraulic, mechanical or electrical) and computers.
Mechanical
Mechanical or manually operated flight control systems are the most basic method of
controlling an aircraft. They were used in early aircraft and are currently used in small
aircraft where the aerodynamic forces are not excessive. Very early aircraft, used a system
of wing warping where no conventionally hinged control surfaces were used on the wing, and
sometimes not even for pitch control as on the Wright Flyer I and original versions of the
1909 Erich Taube, which only had a hinged/pivoting rudder in addition to the warpingoperated pitch and roll controls. A manual flight control system uses a collection of
mechanical parts such as pushrods, tension cables, pulleys, counterweights, and sometimes
chains to transmit the forces applied to the cockpit controls directly to the control
surfaces. Turnbuckles are often used to adjust control cable tension. The Cessna Skyhawk is a
typical example of an aircraft that uses this type of system. Gust locks are often used on
parked aircraft with mechanical systems to protect the control surfaces and linkages from
damage from wind. Some aircraft have gust locks fitted as part of the control system.[6]
Increases in the control surface area required by large aircraft or higher loads caused by
high airspeeds in small aircraft lead to a large increase in the forces needed to move them,
consequently complicated mechanical gearing arrangements were developed to extract
maximum mechanical advantage in order to reduce the forces required from the pilots.[7] This
arrangement can be found on bigger or higher performance propeller aircraft such as
the Fokker 50.
Some mechanical flight control systems use servo tabs that provide aerodynamic assistance.
Servo tabs are small surfaces hinged to the control surfaces. The flight control mechanisms
move these tabs, aerodynamic forces in turn move, or assist the movement of the control
surfaces reducing the amount of mechanical forces needed. This arrangement was used in
early piston-engine transport aircraft and in early jet transports.[8] The Boeing 737
incorporates a system, whereby in the unlikely event of total hydraulic system failure, it
automatically and seamlessly reverts to being controlled via servo-tab.
Stick shaker
A stick shaker is a device (available in some hydraulic aircraft) that is attached to the control column,
which shakes the control column when the aircraft is about to stall. Also in some aircraft like the
McDonnell Douglas DC-10 there is/was a back-up electrical power supply that the pilot can turn on to
re-activate the stick shaker in case the hydraulic connection to the stick shaker is lost.
Fly-by-wire control systems
A fly-by-wire (FBW) system replaces manual flight control of an aircraft with an electronic interface.
The movements of flight controls are converted to electronic signals transmitted by wires (hence the
fly-by-wire term), and flight control computers determine how to move the actuators at each control
surface to provide the expected response. Commands from the computers are also input without the
pilot's knowledge to stabilize the aircraft and perform other tasks. Electronics for aircraft flight control
systems are part of the field known as avionics.
Fly-by-optics, also known as fly-by-light, is a further development using fibre optic cables. This has
an added advantage when sensitive electro-magnetic sensors will be operating aboard the aircraft.
Hydro-mechanical
The complexity and weight of mechanical flight control systems increase considerably with the size
and performance of the aircraft. Hydraulically powered control surfaces help to overcome these
limitations. With hydraulic flight control systems, the aircraft's size and performance are limited by
economics rather than a pilot's muscular strength. At first, only-partially boosted systems were used in
which the pilot could still feel some of the aerodynamic loads on the control surfaces (feedback).
A hydro-mechanical flight control system has two parts:
The mechanical circuit, which links the cockpit controls with the hydraulic circuits. Like the
mechanical flight control system, it consists of rods, cables, pulleys, and sometimes chains.
The hydraulic circuit, which has hydraulic pumps, reservoirs, filters, pipes, valves and actuators. The
actuators are powered by the hydraulic pressure generated by the pumps in the hydraulic circuit. The
actuators convert hydraulic pressure into control surface movements. The electro-hydraulic servo
valves control the movement of the actuators.
The pilot's movement of a control causes the mechanical circuit to open the matching servo valve in
the hydraulic circuit. The hydraulic circuit powers the actuators which then move the control surfaces.
As the actuator moves, the servo valve is closed by a mechanical feedback linkage - one that stops
movement of the control surface at the desired position.
This arrangement was found in the older-designed jet transports and in some high-performance
aircraft.
Redundancy
In larger airplanes with an auto-pilot, the pilot can also be seen as a redundant system to fly the plane
if the auto-pilot fails. Even the pilots themselves can replace each other. Even though they are
supposed to do different tasks, all pilots can fly the plane in case of an emergency. In the early days,
up to four pilots were needed to control an airplane, now only two are required for large airplanes.
Sensors
The following sensors are commonly used by FCS. The object is mainly to navigate the aircraft
autonomously. Therefore, an inertial navigation system is used. An aircraft has six independent
degrees of freedom, three rotational and three translational. If they are all measured, it is possible to
navigate and control an aircraft. The rotational movements are measured by three gyroscopes. The
translational movement is measured by accelerometers. Because of the rotational movement of an
aircraft, it is necessary to place the accelerometers on a frame which is referenced parallel to the
Earth's surface. This is done by measurements of the gyro's. In military aircrafts, all measurements are
performed by accelerometers. These are attached rigidly to the aircraft. Three of these are then used to
measure the angular acceleration. By integration, the angles (roll, pitch and yaw) are calculated and
used to derive the translation measured by the other accelerometers.
Control System
The autopilot is a system that serves to diminish the workload of the pilot. After long hours in the air,
the pilot must be concentrated enough to be able to land safely. Another reason to use a control
system in larger planes is the fact that the control surfaces of these planes require large control forces,
which are impossible for a human pilot. Further it is to notice that a computer controlled system is
more accurate.
Sensors will produce a signal according to the direction the aircraft is flying. The control system will
compare this information with the desired direction. If there is a difference between both it will try to
correct the present situation by controlling the actuator. In the more advanced, three-axis systems
more signals will be used than in the one-axis system. The control system will control both the desired
orientation of the plane and the desired course of the aircraft (in direction and altitude). Some
aircrafts, especially the military fighters, are designed to fly unstable. This means that the centre of lift
lies before the centre of gravity. In that case a small deflection from the balanced situation will cause
the aircraft to become unstable and uncontrollable. This behaviour is desired in military fighters to be
able to make short turns and react quickly. The response time will indeed be shorter when flying an
unstable aircraft. Because a human won't be able to control such an aircraft, the control system is very
important to keep the aircraft virtually stable.
Dependability requirement for control systems
Now an important aspect, dependability requirements, is explained. This is applicable to any
embedded control system where the dependability requirement is important. The design of a control
system is an iterative process. Several systems have been used and replaced and nowadays fly-by-wire
is hot topic. Regarding the design criteria and especially the dependability requirement, the designers
have chosen to use two identical computers for the Flight Control (see image). The exact software
implementation is not now, but some question can be posed:
How do you know which signal of which computer is the correct one?
What if one computer breaks down?
Is there enough redundancy?
Maybe some modifications to this configuration can be made. The first possible configuration uses
two computers. It can be useful to run different algorithms, who are developed separately, by different
companies. But these different algorithms are doing the same calculations. The results can be
compared and there can be a voting for one final output signal. Another possibility is to increase the
number of computers. Nowadays as many as 5 computers can be used.
CONTROL SYSTEMS APPLICATION IN POWER INDUSTRIES
Classifying Power Plants
Power Plants are commonly categorized by what primary energy source they use, as well as
how much output they produce, which is typically measured in MW. This presentation will
focus on conventional thermal power plants, in which fuel is burned and the resulting physical
energy spins a turbine, which turns a generator that produces electricity – most renewable
sources of electric generation, such as hydro, wind, and photovoltaic solar, are not thermal and
are referred to as unconventional.
Thermal Power Plants are generally classified by fuel source, as follows:
A controlled fusion reaction using uranium heats water to create steam power.
Nuclear
One of the following fossil fuels is burned:
- Coal
- Natural Gas
- Crude Oil
Fossil
Biological matter derived from living or recently-living materials are burned.
-Switch grass
-Solid Organic Waste
Condensate System
In the Condensate System, condensate is taken from the condenser hot well, circulated through
low pressure heaters, and to the deaerator. The condenser acts as a heat exchanger that serves
the purpose of creating a vacuum which increases the efficiency of the turbine and recovering
quality feed water (condensate).
Main components
• Condenser
• Condensate Pump
• LP Water Heater
Common Control Issues
Minimum Flow Requirement – pump requires constant minimum flow to prevent
overheating and protect it from cavitation’s.
Water Quality – dissolved and suspended impurities need to be ‘blown down’.
Condensate System Control Valve Applications
1. Condensate Pump Recirculation Valve: Used to allow additional flow required through the
pump; outlet pressure from the pump ranges from 300 to 600 psi at temperatures from 100⁰
to 150⁰ F; experiences cavitation’s and must have positive shutoff i.e. a soft seat.
2. Deaerator Level Control Valve: Maintains a level in the deaerator, an open style of feed
water heater. Requirements: High Range ability; Cavitation Protection at Low Flows; Low
Resistance at Increasing Flows.
Feed water System
The Feed Water System provides the boiler with water in the proper volume and at the design
pressure and temperature – this usually means that feed water is delivered to the boiler at
approximately 2400-3200 psig and 300-500⁰ F.
Low Flow – insufficient flow to the boiler can result in overheating of tubes
High Flow – excessive flow can result in wet steam entering the turbine and damaging the
turbine blades
Common Control Issues
• Low and High Pressure Feed Water Heaters
• Deaerator
• Boiler Feed pump
Application of Optimization Techniques in the Power System Control
The electric (and heat) power generation are more than a century old technology but each
element of the system contains high-tech solutions (power plant technology, generators,
transformers, power lines, power electronic devices, Supervisory Control and Data
Acquisition, etc.) The controlled elements are several millions so the system operation,
stability, control, balance, optimization, settling is a really complex and distributed task.
Power Plant Efficiency Opportunities
Level control applications in power plants lend themselves to performance improvements that
can enhance a plant’s overall safety, efficiency or profitability. Technologies offering more
precise level indication that are not affected by process variables provide operators with the
ability to better manage overall power plant performance. For example, feed water heaters in
coal-fired plants historically suffer from inefficiencies due to poor level controls, which
increase heat rate, thus reducing efficiency. The illustration below indicates some of the most
common level control applications in the power generation industry.
1. Fuel Oil Storage: Crude oils with lower flash points represent a greater fire hazard and
require safety-certified liquid level switches and transmitters.
2. Open Atmosphere Sumps: Level control in collection and processing basins must
often tolerate corrosive media, punishing weather conditions and liquids with high
solids content.
3. Condensate Storage: Accurate, reliable liquid level monitoring in the condensate
storage tank ensures the proper supply of make-up water.
4. Deaerator: Pressure fluctuations are extensive in the deaerator and result in flashing,
thereby requiring level controls that can withstand varying temperatures and pressures.
5. Condensate Drip Legs & Drains: Level instrumentation must contend with high
temperatures and pressures associated with drip legs, to ensure proper functioning of
the condensate collection system and prevent damage to the turbine.
6. Steam Drums: Precise level in the steam drum is important to optimize steam/water
separation and steam quality.
7. Condenser Hot well: Level control in the hot well can prevent make-up water loss in
the turbine cycle due to leakage, steam venting, or other usage.
8. Feed water Heaters: Feed water heater level is controlled to prevent damage to
expensive hardware, while at the same time optimizing level control to improve
efficiency (heat rate) during base load, as well as load following operations.
9. Boiler Blow down Tank: Good boiler blow down practices reduce water treatment
needs and operation costs, as well as the chance of catastrophic explosion.
10. Lubrication Oil Tanks: Reliable level monitoring of lube oil reservoirs ensures proper
functioning of turbines, electrical generators and other equipment with integral
lubrication systems.
11. Ammonia/Caustic/Acid Storage: Managing hazardous and non-hazardous chemical
storage inventory and replenishment safely and reliably is critical to ensure availability
during normal operation.
12. Cooling Tower Basin: Proper level control in the cooling tower basin eliminates lowlevel damage to pumps, while preventing costly overflow conditions. Vulnerability to
foam from chemical injection and modest build-up considerations are fundamental to
selecting the correct level technology.
CONTROL SYSTEM APPLICATIONS IN BIOMEDICINE
Significant increases in processing power, coupled with the miniaturization of processing units
operating at low power levels, has motivated the embedding of modern control systems into
medical devices. The design of such embedded decision-making strategies for medical
applications is driven by multiple crucial factors, such as:
(i)
Guaranteed safety in the presence of exogenous disturbances and unexpected system
failures;
(ii)
Constraints on computing resources;
(iii) Portability and longevity in terms of size and power consumption; and
(iv)
Constraints on manufacturing and maintenance costs. Embedded control systems are
especially compelling in the context of modern artificial pancreas systems (AP) used
in glucose regulation for patients with type 1 diabetes mellitus (T1DM). Herein, a
review of potential embedded control strategies that can be leveraged in a fullyautomated and portable AP is presented. Amongst competing controllers, emphasis is
provided on model predictive control (MPC), since it has been established as a very
promising control strategy for glucose regulation using the AP. Challenges involved in
the design, implementation and validation of safety-critical embedded model
predictive controllers for the AP application are discussed in detail. Additionally, the
computational expenditure inherent to MPC strategies is investigated, and a
comparative study of runtime performances and storage requirements among modern
quadratic programming solvers is reported for a desktop environment and a prototype
hardware platform.
In spite of its success in industrial and domestic applications, control and systems technology
has yet to make significant contributions in the field of biomedicine. In fact, it is anticipated
that control systems principles and methodologies may open up new opportunities in healthcare
by virtue of their potential to revolutionize the quality of clinical care, in the context of patient
monitoring, disease prediction and diagnostics, and treatment and therapy.
Developing control systems for medical applications poses significant challenges, some of
which are unique to this field. Physiological systems involve a multitude of interacting
subsystems and networks, with multiple feed forward and feedback loops. The dynamics vary
both between different individuals and within the same individual over time. Measurement and
estimation of both inter- and intra-patient variability poses a major challenge in the
development of efficient controllers for biological and medical systems. Furthermore, many of
the important states of these systems cannot be measured, and at times cannot even be
estimated. The quantification of clinical objectives is another challenge, as they do not easily
translate into the mathematical performance measures common in control systems theory.
A very simple example of a feedback control system is the thermostat. The input is the
temperature that is initially set into the device.
•Comparison is then made between the input and the temperature of the outside world.
•If the two are different, an error results and an output is produced that activates a heating or
cooling device.
•The comparator within the thermostat continually samples the ambient temperature, i.e., the
feedback, until the error is zero; the output then turns off the heating or cooling device.
Example
•The seemingly simple act of pointing at an object with a finger requires a biological control
system consisting chiefly of the eyes, the arm, hand and finger, and the brain. The input is the
precise direction of the object (moving or not) with respect to some reference, and the output
is the actual pointed direction with respect to the same reference.
•A part of the human temperature control system is the perspiration system. When the
temperature of the air exterior to the skin becomes too high the sweat glands secrete heavily,
inducing cooling of the skin by evaporation. Secretions are reduced when the desired cooling
effect is achieved, or when the air temperature falls sufficiently. The input to this system may
be “normal” or comfortable skin temperature, a “set point,” or the air temperature, a physical
variable. The output is the actual skin temperature.
A Model of Heart Rate Control System
Cybernetics in Biomedicine is related to Biomedical Engineering, Human Movement Science,
Physiology, Dynamic Systems Theory, Instrumentation, Embedded Systems and Control
Engineering. It thus overlaps with many of the department's other research fields. Activities in
this field represent the application of methods from cybernetics and control engineering to
problems that are related to the human body, mainly in a health perspective. As of 2015, our
research activities include the following areas:
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Multi-modal Biomedical Instrumentation
Model Based Diagnosis, Treatment and Assessment
Movement Analysis
Bio signal Processing and Classification
Rehabilitation Engineering
Applications:
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Automatic Glucose Control in Diabetes (Artificial Pancreas)
Early Diagnosis of Cerebral Palsy
Analysis and Diagnosis of Neck Movements
Robot-Assisted Motor Rehabilitation
Prosthesis Control Systems
Integration of Artificial and Biological Neural Systems