Edith Cowan University ENS5253: Feedback Control Systems Case Study

This case study report examines feedback control systems in automobiles, focusing on various applications like electronic fuel injection (EFI), anti-lock braking systems (ABS), and electric power steering (EPS). The report details the control objectives, such as maintaining optimal air-fuel ratios in EFI systems, preventing wheel lock-up in ABS, and providing responsive steering in EPS. It explores the performance of controllers within these systems, including closed-loop control for emission reduction and the use of sensors and electronic control units (ECUs) to manage system functions. The report further discusses system implementation, including the components and mechanisms involved in each control system, referencing relevant research and examples. The study also covers the identification of control objectives, problems faced, and software configurations, providing a comprehensive overview of feedback control systems in modern vehicles.

Case Study ReportDesign Report Template
Example of a feedback control system in an
automobile
Control Systems
ENS5253
<Student Name, Surname>
<Student ID Number>
<Date>Engineering Design Process

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TABLE OF CONTENTS
1. Introduction
1.1 Description of the Control Objectives
2. Background
3. Objective Selection
3.1 Identification of the Control Objective
3.2 Performance of Controller
4. System Implementation
4.1 Abstracting the Problem
4.2 Problems Faced
4.3 Software Configuration
5 Conclusion
6 Discussion
7 References
8 Appendices
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3. Objective Selection:
3.1 Identification of control Objective:
There are a lot of controls aims, which are fulfilled by the controller feedback in some previous
researches as well for example, in ABS system, ECU and HCU are used as controller. The network-based
model for the unmanned marine automobile in the network atmosphere is situated firstly by picking
various parameters in account such as, network-induced delays, sampler to control station packet
dropouts, packet disordering and network induced delays etc. (Wang & Han, 2018).
this model is extended further with some more parameters such as, control station-to-actuator, packet
disordering, network-induced delays, and both control station-to-actuator and sampler-to-control station
packet dropouts. On the basis of these models, dynamic output feedback controllers are planned for
attenuating the oscillation amplitudes of yaw angle and the yaw velocity error (Wang & Han, 2018).
It can be shown by some benchmark examples as,
 Comparison with the unmanned automobile without control, the proposed output feedback
controllers can diminish the oscillation amplitude for the yaw angle and the yaw velocity error.
 The proposed dynamic output feedback controllers can deliver very small oscillations amplitudes
of the yaw angle and the yaw velocity error than a PI controller.
The feedback law is operated in order to alleviate the linearized system, around the congested and
uniform equilibrium profile. The stability of closed loop system under the proposed control law can be
represented by the construction of Lyapunov function. The performance improvement of the closed loop
system under this proposed method of simulation employs four different metrics. This method quantifies
the performance on the basis of various parameters such as, total travel time, fuel consumption and
comfort (Bekiaris-Liberis & Delis, 2019).
The feedback control system of an active aerodynamics device for motor automobile includes one or
more pressure sensors for fluid pressure detection in one or more hydraulic actuators. These sensors
provide the fluid pressure signal to the vehicle controller. These sensors also calculate an actual down
force values of the signals. A calibrated down force value signal is retrieved by the controller from the
mapping down force data. This mapped down force data stores in the memory. On the basis of this
calibration, the controller determines that the actual down force value differs from the calibrated value.
On this condition, the controller finds a target position for the target down force value for a current
vehicle operating condition and it provides the command to the actuator for moving it from active zero
devices to the target position (Bray et al., 2019).
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Another example of the controller feedback is a vehicle with traction battery of at least one cell. This
system includes a controller occupied with the traction battery which is programmed for modifying the
traction battery current. This controller is modified by which the difference between lithium plating
parameter actual value and lithium plating parameter target value will be reduced. The lithium plating
indicator may be based on a differential open circuit voltage of the battery cell or a proportion of the
differential voltage of one cell as a function of time to the cell charging rate of one cell (He, Wang &
Chen, 2017).
An on-board automation computer system for a vehicle includes one memory and one processing unit.
This memory has the storage of computer executable commands which is helpful in implementing the
various aspects of PCC or Predictive cruise control system. In one aspect, the computer system delivers a
plurality of available speed control bands for the PCC system. The available speed control bands in this
aspect are selected by a vehicle operator.
In different aspect, the computer system provides two margins as one upper margin and one lower margin
for the PCC system. These margins are adjustable by the vehicle operator. The relatable notifications can
be represented by an operator surface (for example, touchscreen display provided on the dashboard of
vehicle) (Slaton et al., 2018).
The research on an acoustic feedback system for example, on board vehicle acoustic feedback system is
done already. Different types of sensors are installed in the vehicle for safety conditions and assessing the
performance. One sensor, from this category interfaces with the graphical display for showing the
gravitational force incident on the automobile. However, it is investigated that the graphical display can
distract the attention of the vehicle’s driver. Hence, the usage of graphical display is unsafe especially
during the high performance driving. So, an on-board vehicle acoustic feedback system is used instead of
the graphical display (Pan, 2017).
There are various parts of automobile, in which the control system is used as shown below:
Electronic fuel injection (EFI):
An electronic fuel injection system has various devices such as, a fuel pump, a fuel tanks and at least one
pump. In this system that one pump is operatively coupled in between the fuel tank and the engine, and
the engine is coupled with the fuel pump. The fuel pumps system with the land vehicles consist of a pump
inlet (Simons et al., 2017).
EFI system or electronic fuel injection system is used for both diesel and gasoline engine (Jnr & Haneen,
2019). There are several issues with the carburettors, which is required for the charge preparation in the
gasoline engines. Some of the issues are shown below:
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 In the multi-cylinder engine, non-uniform distribution of the fuel.
 Volumetric efficiency or Poor breathing capacity of the engine.
 Detonation problem.
 Fuel loss in two stroke engines due to scavenging.
To minimize the issues, gasoline engines use EFI system, now days. Electronic fuel system has a
computer and a solenoid operated fuel injector to meter, which is use for injecting the right quantity of
fuel into the cylinders.
An electronic control unit, which is the part of EFI system, receives the data in terms of electric signal
from the sensors. These sensors are implemented on the various parts of the engine. On the basis of
engine’s necessities, EFI system injects the right quantity of the fuel into the engine. It shows the positive
outcome in form of less un-burnt fuel in the emission process.
There are some basic features of EFI system shown below:
 Permits the fast and precise control of injected fuel.
 By ‘on time’ period control of the solenoid operated plungers and injectors.
 Pressure of delivery pipe fuel is maintained constant by the fuel pressure regulator.
 Opening and the closing times in between 0.5 to 1 milliseconds.
 Operating speed of engine at 6000 rpm (10ms revolution time)
 Injectors in time can be controlled in between the time period of 1 to 10ms (Namigtle-Jiménez et
al., 2019).
Figure.1 EFI system in automobile ("How it Works EFI System")
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Power driver application:
EPS or electric power steering is an essential part of new cars, now days. A Solid metal steering shaft
runs from the steering wheel to the steering rack in EPS system. It steers the tires, but the rest parts of the
EPS system is high-tech. EPS system has an essential part named as the electric motor, which is used to
draw energy from the electrical system of vehicle to the steering assistance. The electric motor can be
situated in two arrangements in EPS system. The first arrangement is direct on the steering rack; this is
the most expensive arrangement, which tends to be used on the luxury or the sports car. Another
arrangement could be mounted on the steering column. Sensors are used to detect the torque of the efforts
made by the driver on the steering wheel, and the computer decides the assistance required to be added.
In most of the systems, the computers changes the steering efforts on the basis of the vehicle speed at
different parameters such as, steering light and easy turns, parking speeds, highway speeds, arms up
efforts, greater stability and control (VanderWerp, 2020).
 Sequential or multi-point injection, with single fuel injector near the intake valve of every
cylinder.
 A fuel injector IC package is connected, at the device level
 Delivers high solenoid driver current which is needed for the operation.
 Incorporates both short-circuit and over voltage protection (Huang et al., 2017).
 Connection with the fault reporting diagnostic routines.
Figure.2 Power driver system with various controllers in automobile (Huang et al., 2017)
3.2 Performance of controller:
Closed-loop control of air–fuel ratio
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 The main aim is the low exhaust gas emission levels
 It is mandatory to maintain the air to fuel ratio as 14.7:1, which is chemically perfect.
 For emission control, it has three way catalytic converters
 The fuel injection time period, which is computed by air intake measurement, is modified in the
closed loop control system.
 The performance can be measured on the basis of EGO content.
 EGO clarifies whether it is λ < 1 or λ > 1 (Yildiz, 2018).
 The close loop system has a limit cycle frequency between 0.5Hz to 2 Hz.
Figure.3 Air/Fuel Ratio in automobile (Carley, 2019)
Anti-lock braking systems (ABS):
The basic theory or the basic principle of the anti-lock braking system is very simple. It is used for the
prevention purpose of wheels from locking up, by which it can be possible to avoid the uncontrolled
skidding. ABS system generally offers the enhanced vehicle control and it minimizes the stopping
distances on slippery and dry surfaces (Daftardar et al., 2019).
ABS system has four main components as shown below:
 Speed sensor:
This sensor is used to monitor the speed of every wheel, and it also determines the required
acceleration and deceleration of the wheels. It involves an exciter and a magnet assembly. This
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magnet assembly produces the electricity pulses as the exciter’s teeth passes in front of this
device.
 Valves:
The valves are used for the regulation of air pressure to the brakes during the ABS operation.
There is a valve at brake line for every brake, which is controlled by the ABS system itself. At
initial position, the brake valve is open, so it permits the master cylinder pressure to be transmitted
to the brakes. In the second position, the brake valve remains closed and the master cylinder
pressure of the brakes is constrained. At the third position, the valve allows some of the pressure
to the brake.
 Electronic Control unit or ECU:
ECU is an electronic control unit, which is used for receive, filter and amplify the sensor signals,
these sensor signals are used to calculate acceleration and wheel rotational speed. The ECU
receives the sensor signal in the circuit, and it controls the brake pressure on the basis of analysed
data by the unit.
 Hydraulic Control Unit:
This unit receives the signals from the ECU for applying and releasing the brakes under the anti-
lock conditions. HCU controls the brakes by enhancing the hydraulic pressure or bypassing the
pedal force, which is helpful for reducing the braking power.
The diagram shown below elaborates the wheel-speed and braking pressure during the ABS controlled
braking, it can be clarified in three cases as shown below:
 When the wheel decelerates beyond a particular level, the curtail brake starts pressure.
 When the wheel decelerates further, it minimizes the brake pressure further
 When the wheel accelerates, it increases the brake pressure (Aghasizade & Mirzaei, 2017).
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Figure.4 Vehicle speed and wheel speed in Antibraking system for automoobile ("Modeling an
Anti-Lock Braking System")
4. System implementation:
4.1 Abstracting the problem:
The analysis in this case study is done on the active control of the broad band noise, which is produced
due to the tyre and road contact in the car cabin. The aim of the proposed control approach is to compute
the achievable performance, which depends upon the frequency bandwidth in which the attenuation is
desired. In this case study, this investigation is explored through the MIMO active noise control solution,
which optimises the attenuation level under the explicit robust constraints.
4.2 Problem faced:
The active noise control device consists of three microphones, four loudspeakers, which are placed in the
roof and a controller implementation. The noise measurement contribution source is generally expensive
in terms of industrial constraints. For example, the solutions with accelerometers connection in vehicle
suspension are not appropriate for the mass production. Hence, the present study assumes that such kind
of measure is not available, by which it can lead to the pure feedback control structure. This model
obtainment involves the spectral factorization.
Unfortunately, the investigation on the demonstrative range of the noise is challenging due to the huge
number of involved parameters and variables such as, temperature, vehicle load and road surface etc.
Hence, it is not considered in the present study. The current block scheme has the perturbation source as
road excitation and tyre, and the resultant noise in the car cabin as Yp. (Loiseau et al., 2017).
Gp is transfer between Yp and up. It is usually known as primary path, in ANC. The scheme’s upper part is
unknown. The lower portion of the scheme, u = us is the control input signal, which is applied to the
loudspeaker. Ys is the resulted anti-noise and Gs is the transmission between the microphones and the
loud speakers. The actual noise in the car cabin is the addition of noise Yp and anti-noise Ys. The only
measured output is y = e (Loiseau et al., 2018).
4.3 Software Configuration:
Excel software is used for the graph optimization from the tale and the corresponding results are shown
below.
For Vehicle:
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The validation process of the vehicle is harder than the IRCCyN box, due to the measured models which
are on higher order. It is also due to the various transfers of the vehicle which can have the significant
magnitude level differences.
For SISO Configuration:
The additional complexities make the direct MIMO identification unsuccessful on the vehicle. Hence, the
methodology follows the SISO transfer identification separately, as these transfers share the dynamics.
The obtained MIMO model after the concatenation process reduces to eliminate the repeated dynamics.
Fit = 100
( ||H ( jw ) − ^H ( jw )||2
||H ( jw ) −H ( jw )||2 )
Where,
H(jw) = Calculated frequency response of the system,
^H ( jw ) = Model or assumed frequency response,
H ( jw ) = mean or average of H(jw) over w.
Fit LS1 LS2 LS3 LS4
M1 70 35 30 70
M2 80 70 40 70
M3 60 60 70 30
Table 1.Fit indicators in the SISO model orders (Loiseau et al., 2018)
M1 M2 M3
0
50
100
150
200
250
300
LS4
LS3
LS2
LS1
Figure.5 Graph of evaluated result
For MIMO Configuration:
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Reduction id done through the balanced truncation, which leads to a MIMO model of order n = 158. Fit
values are obtained in the table shown below. The reduction does have any significant impact on the
identification quality.
Fit LS1 LS2 LS3 LS4
M1 88.3293 76.9562 84.1409 80. 7295
M2 83.8304 85.7894 79.1181 83.7762
M3 81.1993 74.332 91.0322 88.5743
Table 2.Fit indicators in the MIMO reduced order model (Loiseau et al., 2018)
M 1 M 2 M 3
0
50
100
150
200
250
300
350
400
LS 4
LS 3
LS 2
LS 1
Figure.6 Graph of evaluated result
5. Conclusion:
In this analysis, the complete approach for computing the attainable performances in the broadband ANC
issue is represented. The general frame work, from the identification to control permits the authentication
of the entire method on experimentation and simulation is planned.
The core influence of this analysis is the demonstration of robust broadband attenuation by the feedback
control. It can be noted that the obvious existence of the waterbed impact inherent to the feedback control
scenario.
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