Overview of automotive
The utilization of automobiles has indeed become indispensable in contemporary times, serving as the primary mode of road transportation worldwide. With their remarkable level of mobility and versatility, automobiles have ingrained themselves in our daily lives, playing a crucial role in transporting passengers and goods They have become critical components of national economic development and contribute to the preservation of national defense.
The history of automobiles can be traced back to the 17th century when the concept of a steam-powered vehicle was first mentioned In 1672, the groundwork for automobiles was laid with the creation of a steam-powered vehicle However, it took nearly a century for Nicolas-Joseph Cugnot to design and build the first steam-powered automotive capable of transporting people in 1769 This groundbreaking invention marked the beginning of the automotive industry as we know it today.
The 19th century witnessed a surge of inventors and innovators who took risks and pushed the boundaries of automotive technology Inventions such as the de Rivas engine, one of the earliest internal combustion engines, and early electric motors emerged during this time Samuel Brown made significant strides by testing the first internal combustion engine with industrial applications in 1826 However, the progress of the automobile industry faced a setback in the middle of the 19th century due to concerns about the colossal size of vehicles.
Nonetheless, certain advancements in internal combustion engines persisted,particularly those that utilized gasoline as fuel The development of two- and four-stroke combustion engines led to a transformative shift in engine technology Carl Benz, a notable figure in automotive history, played a pivotal role in this transformation He introduced the gasoline-powered vehicle and successfully reproduced it in significant quantities, marking a turning point in the history of automobiles This innovation paved the way for the first practical modern automobile capable of mass production.
The Ford Motor Company further revolutionized the automotive industry with the introduction of the Ford Model T in 1908 This groundbreaking achievement marked a significant milestone in car production, as it was the first car to be mass- produced on a moving assembly line This innovation drastically reduced production costs and made automobiles more affordable and accessible to the general public TheFord Model T's success not only transformed the transportation landscape but also brought about profound social and economic changes.
Since the introduction of the Ford Model T, the automotive industry has witnessed remarkable advancements in design, technology, and safety features. Passenger cars have become more refined, efficient, and environmentally friendly. Innovations such as improved engines, hybrid and electric vehicles, advanced safety systems, and autonomous driving technology have propelled the industry forward.
Today, passenger cars come in various shapes, sizes, and configurations to meet the diverse needs and preferences of consumers From compact hatchbacks to luxury sedans, SUVs, and sports cars, there is a wide range of options available in the market. Modern passenger cars offer comfort, convenience, and advanced features that enhance the driving experience They are equipped with state-of-the-art infotainment systems, connectivity features, and driver-assistance technologies, making them not just a means of transportation but also mobile entertainment and communication hubs.
Furthermore, passenger cars continue to evolve in response to global concerns about environmental sustainability Automakers are increasingly focusing on developing electric vehicles (EVs) and improving fuel efficiency to reduce emissions and dependence on fossil fuels The shift towards cleaner and more efficient propulsion systems is reshaping the automotive industry and contributing to a greener future.
In conclusion, the history of passenger cars has witnessed remarkable progress,from the early steam-powered vehicles to the mass-produced automobiles of today The inventions and innovations of pioneers like Carl Benz and the Ford Motor Company have shaped the industry and paved the way for modern transportation With ongoing advancements in technology and a growing focus on sustainability, passenger cars continue to evolve, offering enhanced performance, safety, and environmental friendliness The automobile industry remains a vital force in our society, facilitating personal mobility, economic growth, and societal development.
Overview of Camry models of Toyota
The Toyota Camry is a renowned mid-size car that has carved a remarkable legacy since its introduction by Toyota in 1982 With its widespread acclaim and impressive sales figures, the Camry has firmly established itself as one of the best- selling cars in the world Its reputation stems from a winning combination of exceptional reliability, comfortable ride quality, and impressive fuel efficiency.
The Toyota Camry series encompasses a range of models, each tailored to cater to diverse needs and preferences Let us delve deeper into the distinctive features and characteristics of each model within the Camry lineup.
First in line is the Toyota Camry LE, serving as the base model of the series. Equipped with a 2.5-liter, 4-cylinder engine, the LE delivers a commendable performance, generating up to 203 horsepower The LE model offers a host of desirable features, including an 8-inch touchscreen infotainment system, complete with Apple CarPlay and Android Auto integration Advanced safety features further enhance the appeal of this model, ensuring a safe and secure driving experience.
Moving up the lineup, we encounter the Toyota Camry XLE, which shares the same engine as the LE but introduces additional features to elevate comfort and luxury. The XLE model spoils its occupants with heated front seats, dual-zone automatic climate control, supple leather upholstery, and an upgraded audio system These refined touches enhance the overall driving experience, providing a sense of opulence and sophistication.
For those seeking a better spirited and sporty ride, the Toyota Camry SE is an excellent choice Equipped with the same engine as the LE, the SE model boasts a firmer suspension, larger wheels, and a sport-tuned suspension system These enhancements contribute to enhanced handling and a more engaging driving experience Additionally, the
SE model stands out from the crowd with its unique styling elements, such as a distinctive black mesh grille and an eye-catching rear spoiler.
Taking the sporty essence even further, the Toyota Camry XSE builds upon the
SE model and adds a range of additional features With the same engine as the SE, the XSE offers sport front seats, a panoramic sunroof, and an impressive 9-speaker audio system These elements enhance both the comfort and entertainment aspects, enveloping occupants in a premium and immersive driving environment.
Last but certainly not least, the Toyota Camry TRD stands as the most performance-focused model in the lineup It features a robust 3.5-liter V6 engine that churns out an exhilarating 301 horsepower With a lowered suspension, enhanced brakes, and larger 19-inch wheels, the TRD model delivers a heightened level of thrills and excitement Its dynamic capabilities make it an ideal choice for enthusiasts seeking an engaging and spirited driving experience.
In conclusion, the Toyota Camry series offers a diverse range of models, ensuring that there is a Camry to suit individual’s preferences and requirements Whether one seeks a practical and reliable sedan, a luxurious and comfortable ride, or a sporty and exhilarating driving experience, the Toyota Camry delivers on all fronts With its unwavering commitment to quality, performance, and customer satisfaction, the ToyotaCamry continues to dominate the mid-size car segment and captivate drivers worldwide.
Overview of suspension system
Objective of the suspension system
The objective of the suspension system in a vehicle is to provide a smooth and comfortable ride, enhance vehicle stability, and ensure optimal tire contact with the road surface The suspension components play a crucial role in achieving these objectives by performing various tasks.
One of the primary tasks of the suspension system is to incorporate an elastic element that reduces dynamic loads applied from the wheels to the vehicle frame This elastic element, often in the form of springs, helps absorb shocks and vibrations caused by uneven road surfaces By absorbing these forces, the suspension system ensures a smoother ride, minimizing discomfort for the occupants and preventing excessive stress on the vehicle's structure.
Furthermore, the suspension system acts as a guide unit, transmitting longitudinal and transverse forces as well as magnetic moments from the road to the vehicle chassis The kinematics of the suspension system determine the relative oscillation of the wheels with respect to the frame This allows the suspension system to maintain tire contact with the road surface, even when encountering irregularities.
By doing so, the suspension system enhances vehicle stability, handling, and traction, particularly during cornering, braking, and acceleration maneuvers.
Shock absorbers, an integral part of the suspension system, play a crucial role in dampening the vibrations of the suspended and unsuspended parts of the automobile. When a vehicle encounters bumps or road imperfections, the springs in the suspension system absorb the initial impact However, the energy stored in the springs can cause the vehicle to continue oscillating The role of shock absorbers is to dissipate this energy, reducing the amplitude and duration of the oscillations By effectively controlling these oscillations, the suspension system improves ride comfort, stability, and overall control of the vehicle.
In addition to the primary objectives mentioned above, the suspension system also influences other important aspects of vehicle performance, such as braking and tire wear.
By maintaining optimal tire contact with the road surface, the suspension system aids in maximizing the effectiveness of the braking system It ensures that the tires maintain proper traction, allowing for efficient braking and minimizing stopping distances.
Moreover, the suspension system helps to distribute the vehicle's weight evenly among the tires This even weight distribution plays a crucial role in minimizing tire wear By preventing uneven tire wear, the suspension system promotes longer tire life, reducing the frequency and cost of tire replacement.
In conclusion, the objective of the suspension system in a vehicle is to provide a smooth and comfortable ride, enhance vehicle stability, and ensure optimal tire contact with the road surface Through the use of elastic elements, guide units, and shock absorbers, the suspension system effectively reduces dynamic loads, transmits forces, and dampens vibrations By achieving these objectives, the suspension system contributes to overall vehicle performance, including ride comfort, stability, braking efficiency, and tire longevity.
Requirements of suspension system
An active suspension system in a vehicle should have the following requirements:
− Adjustability: An active suspension should be adjustable to suit different driving conditions and driver preferences It should allow the driver to adjust aspects like damping force, spring stiffness, ride height, etc Adjustability allows optimizing the ride quality and handling for different loads or driving styles.
− Improved ride comfort: The primary aim of an active suspension system is to provide an enhanced and comfortable ride quality It should effectively absorb road irregularities and dampen vibrations to provide a smooth ride for passengers This results in less fatigue and a more pleasurable driving experience.
− Improved handling and stability: An active suspension should also improve the handling, steering and stability characteristics of the vehicle It can control the suspension dampening and ride height on each wheel individually based on the vehicle dynamics This allows providing more grip and control, reducing body roll during cornering and ensuring a more planted feel.
− Quick response: An active suspension system should respond quickly to changes in road conditions and driving demands It uses sensors and electronic control units to constantly monitor the suspension and adjust the damping force rapidly as needed A quick response results in better control and allows the suspension to adapt instantly for optimized performance, handling and safety.
− Variable damping: Active suspensions provide variable and adjustable damping force based on need Instead of the fixed damping provided by passive suspensions, the damping can be softened or stiffened electronically based on speed, load, road conditions, driver input and more This allows maximizing performance in different conditions rather than compromising Variable damping is key to the benefits of active suspensions.
Structure of suspension system
− Elastic part: Facilitates wheel oscillation, has the effect of bringing the vehicle's oscillation frequency in line with the appropriate frequency range for the user, ensuring smoothness when the vehicle is in motion and full support on vehicle weight set.
• Leaf-spring (Mainly on trucks)
• Compressed air (Luxury cars like Merc S class, BMW 7, etc.)
− Driven unit: It determines the movement of the wheel to the chassis of the vehicle Receiving and transmitting force and torque between the wheel and the chassis.
− Shock absorber: Has the effect of canceling the oscillation of the wheel and body to ensure better traction of the wheel, increasing the smoothness and stability of the vehicle.
• Hydraulic damper (Most cars now use this type).
• Mechanical friction (Leaf-spring on the suspension also play a part in damping thanks to friction between the springs).
Classification based on assembly
In automobile applications, a variety of suspension systems are employed, including independent suspension, dependent suspension, torsion bar suspension, and air suspension Each kind has benefits and disadvantages of its own, and is chosen depending on the particular requirements of the vehicle.
Suspension systems may be divided into many sorts according to their construction and use The two most popular types of suspension systems are dependent and independent Both wheels are connected to the same axle via a dependent suspension system, which means that any movement or shock received by one wheel also impacts the other While each wheel may move independently with an independent suspension system, less movement is transferred between the wheels. Also, there are several independent suspension system designs, such as double- wishbone and multi-link suspension systems, each having special advantages and traits.
The wheels are attached to the same bridge girder, which will also be attached to the car's body This basic suspension style is ideal for heavy vehicles because of its excellent durability traits Yet when the automobile is not carrying anything, the mechanism becomes very stiff, unreliable, and susceptible to vibrations.
1.3.4.1.1 Twist-beam suspension (Torsion suspension):
Figure 1 14 Twist-beam suspension components
Figure 1 15 Twist-beam rear suspension of Audi A1
A form of suspension system called twist-beam suspension is frequently used in less expensive and smaller vehicles It is made to offer a balance between handling and riding comfort while still being reasonably priced It comprises of a solid beam with a pivot joint in the middle that connects the back wheels.
− Advantages of Twist-beam suspension:
• Cost: Comparing twist-beam suspension systems to other types of suspension systems, twist-beam suspension systems are often less expensive to develop, produce, and maintain Because of this, it is a desirable choice for automakers of compact or inexpensive vehicles.
• Compact size: This sort of suspension system has a very straightforward design, which means it takes up less inside room, which can be crucial in smaller vehicles.
• Better Handling: Compared to conventional live-axle suspensions, twist-beam suspensions offer superior handling because the pivot point lessens the unsprung mass of the rear wheels, increasing their traction on the ground.
− Disadvantages of Twist-beam suspension:
• Limited comfort: Twist-beam suspension systems do not provide as much shock absorption as more sophisticated ones like independent rear suspension or multi-link suspension This can result in a less pleasant ride, especially on bumpy terrain.
• Limited adjustability: Twist-beam suspensions can't be easily adjusted to improve performance because of their limited flexibility.
• Uneven weight distribution: The solid beam that connects the wheels may result in an unequal weight distribution, which may impair handling and cornering, especially at high speeds.
1.3.4.1.2 Solid axle suspension (Live axle):
Figure 1 16 Solid axle suspension components
An older style of suspension frequently found in bigger vehicles like trucks and SUVs is solid axle suspension It is made composed of a single beam that spans the width of the automobile, links the wheels, and supports the weight of the car with coil or leaf springs.
− Advantages of solid axle suspension:
• Durability: Systems with solid axle suspensions are renowned for their robustness and capacity to carry big loads They are more durable against damage from pebbles and other debris and can tolerate harsh terrain.
• Simplicity: It may be simpler and less expensive to fix and maintain solid axle suspension since it is less complex than other types of suspension systems.
• Towing and hauling capacity: Solid axle suspension systems are perfect for bigger vehicles like trucks and SUVs since they are made to bear huge weights and pull trailers.
− Disadvantages of solid axle suspension:
• Poor handling: Solid axle suspensions do not offer the same level of responsiveness or control as other, more sophisticated suspension systems This can make the ride rougher and less pleasant, especially over rocky terrain.
• Uneven weight distribution: Uneven weight distribution may come from the solid axle connection, especially in smaller cars During cornering, this can have an impact on handling and lead to stability problems, especially at high speeds.
• Reduced fuel efficiency: As solid axle suspension systems are often heavier than other kinds of suspension systems, their fuel efficiency may suffer.
The wheels will be mounted to the vehicle's body separately from one another rather than being linked to one another They are therefore entirely independent of the other wheels and may travel in any direction.
The independent suspension system has a significantly more intricate construction than the dependent suspension system Vehicles utilizing this technology have excellent traction and fluid mobility The chassis may be built low since bridge girders are not required.
It will be separated into the following types of suspension due to the more complicated independent suspension, which is based on the elastomer and damping parts:
1.3.4.2.1 MacPherson strut (single control arm):
Consists of 3 basic parts: hydraulic shock absorbers, springs and steering arms, reducing the number of points attached to the chassis from 4 to 2, the shock absorber is the guiding part of the system to only one bar The lower crossbar is attached to the wheel hub.
With a simpler, less detailed design, MacPherson helps speed up the assembly process, lowers production costs, reduces weight and creates more space for the very compact engine compartment of front-wheel drive vehicles, and at the same time makes repair and maintenance simpler and more economical So, this is the most common type of suspension on cars.
• The MacPherson strut has benefits and drawbacks One of the benefits we just mentioned is the possibility to use a driveshaft in front-wheel without making any modifications.
Classification based on the level of control and adjustability
Automotive suspension systems play a critical role in providing comfort, stability, and handling characteristics to vehicles Over the years, suspension technology has evolved, resulting in different types of suspensions based on the level of control and adjustability they offer This essay aims to explore the three main types of automotive suspensions: passive, semi-active, and active Each type possesses distinct characteristics that influence ride quality, handling, and adaptability to varying road conditions.
Passive suspensions are the most common and traditional type found in vehicles. They consist of mechanical components, such as coil springs and hydraulic shock absorbers These suspensions do not actively adjust their characteristics but rely on the inherent properties of the components Coil springs provide vertical support and determine the vehicle's ride height and load-carrying capacity Hydraulic shock absorbers, or dampers, control the movement of the suspension by dissipating energy from road disturbances.
Passive suspensions offer a simple and cost-effective solution, but their characteristics are fixed and cannot be altered in real-time They provide a balance between ride comfort and handling, typically prioritizing comfort However, the performance of passive suspensions may vary depending on road conditions and vehicle dynamics, resulting in limitations in adapting to changing environments.
Semi-active suspensions bridge the gap between passive and active systems They incorporate electronically controlled dampers that can adjust damping characteristics in real-time These dampers use sensors to monitor vehicle parameters, such as wheel acceleration, body roll, and road conditions, allowing for adaptive responses.
The advantage of semi-active suspensions lies in their ability to provide improved ride comfort and handling compared to passive suspensions By altering damping forces,they can adapt to different road conditions and mitigate excessive body movements Semi- active suspensions offer different modes or settings, allowing drivers to choose between comfort-oriented or sportier settings based on their preferences.
However, semi-active suspensions have limitations compared to fully active systems They cannot actively adjust other suspension parameters, such as spring rates or ride height Additionally, their response time and adjustability may not be as precise or instantaneous as active suspensions Nevertheless, semi-active suspensions strike a balance between cost, performance, and adaptability.
Active suspensions represent the pinnacle of suspension technology, offering the highest level of control and adjustability These systems utilize advanced electronic control units, sensors, and actuators to actively adjust multiple suspension parameters in real-time.
Active suspensions can adapt damping forces, spring rates, and even ride height based on various inputs, including road conditions, vehicle speed, steering angle, and acceleration By continuously monitoring and adjusting, active suspensions can provide optimal performance across a wide range of driving conditions, ensuring superior ride comfort, stability, and handling.
The benefits of active suspensions are numerous They can mitigate body roll during cornering, counteract dive and squat during acceleration and braking, and improve traction by adjusting suspension characteristics according to road conditions. Active suspensions can be further enhanced by incorporating road preview systems that anticipate road irregularities and adjust the suspension proactively.
In conclusion, automotive suspension systems can be classified into three main types: passive, semi-active, and active Passive suspensions are the most common type,offering a fixed balance between ride comfort and handling Semi-active suspensions provide adaptive damping characteristics, allowing for improved ride quality and handling Active suspensions represent the pinnacle of suspension technology, actively adjusting multiple parameters for optimal performance in various driving conditions.Each suspension type has its advantages and limitations, and the choice depends on factors such as cost, performance requirements, and driver preferences As suspension technology continues to advance, future developments may bring even greater levels of control and adaptability to automotive suspensions.
Full car model of active suspension system
Figure 2 1 Full car model with ten degrees of freedom
The full-car suspension model, comprising of a multitude of parts and intricate systems, is indeed the most complex model among all other suspension models in the market In essence, the full suspension model encompasses every component present in a half-car suspension, with the additional implementation of dynamic properties of the vehicle and the geometry of suspension parts to accurately depict the vehicle's behavior during motion.
The comprehensive nature of the full suspension model is exemplified through its various components such as:
− The front suspension, including the spring, damper, upper and lower control arms, steering linkage, and wheel assembly.
− Similarly, the rear suspension comprises of the spring, damper, upper and lower control arms, trailing arms, and wheel assembly.
− The chassis is represented by a rigid structure that houses the engine, transmission, and other critical components of the vehicle.
− The mass-spring-damper system is instrumental in representing the weight of the vehicle, including such components as the wheels, brakes, and suspension parts that are not supported by a spring.
− Additionally, the tire component in the full suspension model is no less than a work of art, accounting for lateral, longitudinal, and vertical forces while considering slip angle, camber angle, and rolling radius.
− The steering and braking systems of the full suspension model are equally comprehensive and include various intricate components such as steering mechanism, steering gear, and steering linkage, brake calipers, brake pads, rotors, hydraulic lines, etc.
The full suspension system model provides engineers with an incredibly powerful tool to optimize and assess the vehicle's complex dynamics and component designs intricately to ensure exceptional ride quality, handling, and stability performance The model can also study the effects of external factors, such as the road condition and vehicle velocity, and how they influence the suspension system's overall efficiency.
Quarter-car model of active suspension system
Figure 2 2 Quarter-car model with one degree of freedom
Figure 2 3 Quarter-car model with one degree of freedom with actuator
The quarter-car suspension model is a rather nifty and streamlined contraption that is often employed in engineering analyses - especially when it comes to simulating and controlling the suspension system It is widely utilized to scrutinize a vehicle's vertical dynamics with regard to a solitary tire - and it happens to be simpler than its half-car counterpart.
The name of this nifty model is based on the fact that it focuses on one wheel and its corresponding suspension components Intriguingly enough, it comprises a handful of deceptively uncomplicated components:
− Spring: This suspension spring is ingeniously structured to bear the weight of the vehicle.
− Damper: The suspension system's motion is regulated by an ingenious mechanism known as the dampener, which expertly disperses energy and provides dampening forces.
− Wheel: The wheel happens to be connected to the suspension system, and it can be epitomized by a simple tire model.
− Mass: In this model, the mass refers to the unsprung mass - which encompasses the weight of the wheel and the other components of suspension.
Engineers are known to assess the efficacy of the suspension system using the quarter-car model by monitoring the wheel's movement under driving conditions One of the fascinating aspects of this scenario is that it can be implemented to analyze how a bump on the road might influence the vehicle's wheel motion in relation to its body.Engineers could adjust various parameters of the model, such as the damping coefficient and the spring constant - which enables them to determine the ideal setup for the suspension system in terms of achieving maximum levels of ride comfort and proficiency in handling performance Furthermore, the quarter-car model provides a viable approach for evaluating distinct suspension systems that can be categorized as passive, semi-active, and active systems.
Half-car model of active suspension system
Figure 2 4 Half-car model with four degrees of freedom
Figure 2 5 Half-car model with four degrees of freedom with actuator
The control equation for the vertical motion at vehicle body can be represented as: ̈ + ( ̇ − ̇ )+ ( − )+ ( ̇ − ̇ )+ ( − )−
- Actuator force of active suspension system
The control equation for pitch moment as followed: ̈ + [ ( ̇ − ̇ ) + ( − ) − ]− [ ( ̇ − ̇ ) +
- Moment of Inertia ̈ - Rotary angle at vehicle’s center of gravity
, - Inter-space between Font/ Rear axle and vehicle center of gravity.
Considering the unsprung mass and analyzing, the vertical moment at front vehicle can be represented by equation: ̈ + ( ̇ − ̇ )+ ( ̇ − ̇ ) − ( − )+ ( −
- Vehicle body unsprung mass at front ̈ - Acceleration of unsprung mass at front
- Stiffness coefficient at front wheel
As well as the rear of vehicle, we have the equation to represent as:
Some of the parameters could be substituted by the following:
Now the equations (1) and (2) will become:
According to the equations (3) (4) (5) and (6) which is represented in the form of State space will be performed as, ̇= + +
The states of the model are defined as, ̇ ̇ ̇ ̇
A reduced vehicle model that is frequently used for research and design of automobile suspension systems is referred to as a half suspension system model of a car or a half-car model The model fills the gap between simple vehicle dynamics analysis
The half-car model is made up of four major parts:
− Front suspension: It is made up of a spring and a damper attached between the car's wheel and chassis.
− Rear suspension: It is also the same as front suspension where a spring and damper are attached between the wheel and the car's chassis.
− Mass-Spring Damper System: This model represents the body of the car and is represented by a mass (m) with a spring (k) and damper (c) connected between the front and rear suspension systems.
− Tire: It is a straightforward tire model that gives the longitudinal (forward and backward) force produced per unit slip angle as well as the lateral (side-to-side) tire stiffness.
The model of half suspension allows the engineers to examine how the suspension system of the automobile interacts with the road surface It may be used to evaluate the vehicle's handling, stability, and ride quality In order to maximize the car's ride comfort and handling performance, the model may also be used to test different suspension system configurations and design elements, such as spring rates and damper settings.
Introduction to matlab/Simulink
Matlab/Simulink is a combination of tools used for numerical computation and simulation, respectively MATLAB is a high-level programming language and interactive environment widely used for data analysis, visualization, and numerical computation Simulink is a companion software application that offers a graphical programming environment for modeling, simulating, and analyzing dynamic systems.
It is often used for designing and testing complex control and signal processing systems in various industries, including automotive, aerospace, and communication. Together, Matlab/Simulink offers a comprehensive solution for technical computing and model-based design.
Figure 3 1 The original display of MATLAB
3.1.2 Basic use of Matlab/Simulink
Matlab/Simulink can be applied in various fields which include:
Matlab allows engineers to organize, clean, and analyze complex data sets from diverse fields such as climatology, predictive maintenance, medical research, and finance.
In matlab environment, many functions are designed for engineers or users can expresses matrix and array mathematics directly without any programming experience requirement From basic mathematical function which run in simple commands can be developed in large-scale applications.
Graphics is an essential function of Matlab when it helps perform the data details in the form of graph Engineers can use it to create custom graphics and interactions In addition, it saves visualizations as image or as vector graphics files including PDF, EPS, and PNG for optimizing sharing and exporting.
Matlab support app builders two primary tasks included in app building That are laying out the visual components of a graphical user interface and programming app behavior Those functions is programed already in Matlab’s library where contain many simple and standard components such as buttons, check boxes, and table.
MATLAB and Simulink application deployment products enable engineers and scientists in your organization to share their work as secured standalone applications, web apps, Docker containers, and other targets with unlicensed MATLAB and Simulink users such as collaborators and clients.
Using MATLAB and Simulink in the cloud enables engineers and scientists to speed up their development processes by providing on-demand access to enhanced compute resources, software tools, and reliable data storage.
Matlab allows many kinds of programing language including C/C++, Fortran, Java, and Python Besides that, converting Matlab code to C/C++ is one of the strengths of it.
Matlab is a versatile and powerful tool for building and deploying deep learning models across various domains It provides a comprehensive set of functions and toolboxes that allow you to build, train, and analyze deep learning models with ease.
Introduction to CarSim
CarSim is a software used to simulate the dynamic behavior of cars and light trucks It precisely reproduces the mechanics of the vehicle in reaction to driver and/or automated controls for steering, throttle, braking, and gear shifting using 3D multibody dynamics models A 3D ground/road surface as well as aerodynamic and wind impacts are included in the environmental circumstances.
As a tool, CarSim has undergone significant validation and correlation to real- world outcomes as measured and observed by several car OEMs worldwide. VehicleSim is the name of the underlying technology that CarSim is built upon; it is referred to as "VS" when referring to additional product content, such as the VS Visualizer (video and charting) and VS Commands (scripting language).
High-Fidelity System-Level Vehicle Models: Since CarSim math models are system-level, they do not require in-depth knowledge of component materials, suspension linkage nuances, etc The vehicle data is designed to be measured or computed To the extent of verifying repeatability, the simulation can duplicate physically measurable reactions since the mathematics modeling the vehicle are sufficiently in-depth To do this, information on the vehicle's kinematics and suspension compliance, tire force and moment characteristics, and environmental factors are needed The math models nevertheless produce representative findings that are suitable for assessing various designs and control procedures when there is a lack of reference data.
Parametric Vehicle Definition: CarSim represents the car using a mix of parameters and variables, according to the definition of a parametric vehicle.Parameters stand substitute for quantifiable qualities like size and inertia, as seen inFigure 1 Configurable Functions employ a range of extrapolation and interpolation techniques to tie model variables to linear coefficients or tables Several of the tables provide data from tire and suspension test rigs Other potentially nonlinear connections that may be imported from spreadsheets, including friction and road geometry, are likewise conveniently represented in tabular form.
Figure 3 5 Parametric and tabular data used in CarSim
ADAS and AV Support: To mimic scenarios involving Advanced Driver
Assistance Systems (ADAS) and/or autonomous cars, CarSim contains moving
"target" objects that are used to represent traffic vehicles, pedestrians, bicycles, etc (AVs) Virtual sensors are used to detect these targets, and each sensor generates 24 computed output variables for every potential sensor / target detection pair.
Database, User Interface, and Documentation: Almost 600 sample simulations made up of one or more automobiles and a set of test circumstances are included with CarSim Almost 40 sample vehicles—representing at least 10 different vehicle configurations—are included in these instances.
The VS Browser is a Graphical User Interface (GUI) that is part of the Windows version Use it to launch CarSim, configure tables and parameters, and see the outcomes. The multiple vehicles, environment, and process displays in the Browser correlate to various vehicle, environment, and procedure data that is kept in a database Each screen features a Help button that, when clicked, displays a paper outlining the screen's purpose and available options The Help drop-down menu contains links to technical documents, reference materials, and tutorials Each document is a PDF file, all of which are housed in a Help folder that has been organized for quick searching using Adobe Reader The item on the Help menu is used to refer to documentation in the text that follows A mention of the CarSim Quick Start Guide may be like follows: Help menu item:
Guides and Tutorials > CarSim Quick Start Guide.
Plots and Visualization: CarSim comes with VS Visualizer, a tool for producing high-quality animation of simulation results matching engineering charts of hundreds (or even thousands) of variables from the math model (Figure 3.6) The charts and video are time-synchronized to make it easier to view qualitative and quantitative data, and the ability to overlay many runs (up to six in total) enables comparisons between various vehicle and control combinations.
Figure 3 6 Viewing synchronized video and plot of CarSim vehicle with VS Visualizer
Fast Calculations: A simulation of a 60-second test will conclude in 3 or 4 seconds on a current Windows machine since the CarSim math model is highly tuned for computation efficiency and often works 15 to 20 times quicker than Windows clock time Under conditions of heavy load, such as the addition of numerous moving objects and sensors and the need to store thousands of outputs to files, the simulation's execution speed may be slowed down On Windows, the simulations still operate quicker than in real life.
Installation: Installation of CarSim on Windows is done via a program called
Setup_CarSim__.exe Once installed, access to CarSim is typically via a shortcut on the desktop or the Start menu Basic Use of CarSim:
If you are running with the Browser and VS Visualizer on Windows, there are several fundamental functionalities in CarSim that may be utilized for nearly any application You may examine the data that was used to create the simulations as well as the results of previous simulations using CarSim Moreover, you may construct new instances by copying and editing old ones to create new simulations utilizing existing car examples.
Run Control: The CarSim Browser's home page may be seen in Figure 3.7 of the Run Control window Libraries in the database folder are used to structure the CarSim GUI displays The title of the dataset being viewed is displayed in the Windows title bar (1) together with the name of the current library (2).
Figure 3 7 The Run Control screen in CarSim (Windows)
Underneath the navigation bar, a row of buttons may be seen The existing dataset can be copied using the Duplicate button (3) before being modified to make room for new data If the dataset is unlocked, locations containing editable text are indicated with a yellow backdrop (9) The section on the left that contains optional comments (4) about the current dataset and a tree representation of the current simulation is shown or hidden using the Sidebar button (8).
Information about the current simulation is available in the drop-down control in the lower right corner (14) and may be viewed (13) using a text editor or spreadsheet(Figure 3.8).
Figure 3 8 Drop-down control for View options
As the simulation starts, a complete description of the model is displayed in the first item on the list (Echo file with startup conditions) (Figure 3.9).
Figure 3 9 Portion of Echo file listing all simulation data
The Echo file is divided into sections that describe several aspects of the model, including the Sprung Mass, Suspension, Powertrain, Tires, Roads, and Routes.
The Interface frequently uses blue customizable hyperlinks with a purpose akin to those seen in web browsers (Figure 3.9) A blue link (5) will emphasize the text similarly to a web link when the mouse pointer is over it The associated vehicle will appear here when you click the blue link from the Run Control screen: datasheet for assembly (Figure 3.10).
Figure 3 10 Blue link to another dataset
With the associated drop-down controls, the hyperlink control is expanded in two different ways Consider the blue link that allows you to specify the vehicle's sprung mass in the screen's top left corner (Figure 3.11).
Figure 3 11 A Vehicle: Assembly dataset used in the example simulation setup
Figure 3 12 Libraries available for a blue link
By clicking the blue Sprung Mass link (1), you can access the associated Sprung Mass screen as well as the underlying dataset A drop-down menu (2) on the top control is used to choose a database library This example demonstrates how CarSim may display the Sprung Mass statistics in two different ways: Sprung Mass and Sprung Mass (from Whole Vehicle) To pick between these two libraries, utilize the top control.
Graphs plot from Matlab/Simulink
After modeling PID Controller-based Active Suspension for half car model, those below graphs are our achievement and demonstrate the theoretical working of control force of actuators using PID control to cancel the force acting on sprung mass of vehicle.
Figure 4 1 Displacement of front unsprung mass
Figure 4 2 Displacement of rear unsprung mass
The figure 4.1 and 4.2 show the displacement of front and rear unsprung mass (suspension) when moving on the specific road condition which is set in a form of sine sweep disturbance.
At the moment, the vehicle encounters the test road (t = 0), the front suspension moves upward according to the deformation of the road, the magnitude of displacement will equal to the height of the bumps The front suspension keeps moving upward and downward the same as the shape of the sine wave signal until the simulation end.
The signal sending to the rear suspension will be delayed in 2 seconds basing on the setting of the model In the waiting time, there would be a few oscillations because of the impact of front suspension Assuming the whole model of half-car is a rigid bar, when the front suspension moving upward by the force of the road acting on, that force would cause a torque on the top of the bar and create pitching moment That would explain for the reason of rear suspension oscillation At the time that the rear reaches the sine wave signal, it performs the same displacement as front suspension until the end of simulation.
Moving onto the target of simulation, the forces act on the vehicle which lead to the displacement According to the motion equation:
• The Figure 4.3 shows the force acts on the front vehicle being represented by is the blue line It would have overshoot at the beginning and gradually become stable after 4 th second and remain the same force magnitude from
5 th second to the end of simulation.
• The Figure 4.4 shows the force acts on the rear vehicle being represented by is the blue line As mentioned before in the reason for displacement of rear unsprung mass, there is pitch moment when the front receives the signal at first. That generate the force acting on the rear while it has not reached the signal yet When the rear vehicle receives the signal, it also has the overshoot and the force oscillate up and down rapidly approximating 2 seconds before becoming stable and acting the force with the same magnitude till ending simulation.
Both suspensions are equipped PID to control the force actuator, the red line in two graphs represent the force that actuator generate to cancel to force deriving from unsprung mass As can be easily seen, the magnitude of those actuator forces is totally opposite with forces which are in blue line.
According to the force being generated by force actuator thanks to the analyzation and adjustment of PID, the output force is opposite, but it cannot generate correctly with the same magnitude However, with the model limitation, that force could be accept and apply to control the final force acting on the front and rear vehicle.
Figure 4.5 Force acting on front vehicle body
Figure 4.6 Force acting on rear vehicle body
On the next two diagrams, blue line keeps representing the force causing the displacement of vehicle in Figure 4.5 and 4.6 But in this time, the red line is also the same force which is the result of being cancelled by the force from actuator The final force acting on the vehicle is reduced optimistically to prevent the displacement of vehicle while moving on the road.
The overshoot of each force decreases dramatically The time which needs to stabilize the force is also less than the initial.
The efficiency of force actuator in active suspension could be seen clearly by those two Figure when the acting force equal nearly 0.
Considering the magnitude of final force, there is still having force acting on the front and rear of the vehicle The reason for that is when receiving signal at the first time,the vehicle would take a time to send feedback to collect the error and provide it as input data for PID to analyze how large of force is to allow the force actuator to generate canceling force So, it requires a short period of time to build a complete flow of feedback signal that can be applied In the case of rear vehicle, it also has force acting at the start point as mentioned, but the force being created by pitch moment is seemed quite small when comparing with the magnitude of force deriving from the first signal of sine wave.That could be used to explain why the final force acting on rear vehicle still have not cancelled totally the overshoot although it already collects the errors in the waiting time.
The Figure 4.7 show the pitch angle of vehicle during simulation The value of pitch angle is minor so that it cannot be considered as having enough ability to see the rotation of the vehicle In this situation, it will acknowledge that there is no rotation of the vehicle.
Figure 4.8 The displacement of vehicle body
At the end of simulation progress, we check the vertical motion of Z which is the final goal of this model The purpose of active suspension system is canceling all the force acting on the vehicle in order to make vehicle body stay unchanged while moving on several roads with different conditions The red line in the Figure 4.8 represents the displacement of Z which is also the displacement of vehicle body
During the simulation time period, Z line always oscillates extremely small This could proof that the vehicle with active suspension system would move without any displacement of body.
According to the final result, it fit with the target that our team initially set at the beginning of the project and try to build a model to achieve that goal Although the theory of active suspension system is just built on the Simulink and demonstrate how it work in model This project still lack experience in real model and cannot perform that in reality to show the best performance of active suspension system.
Graphs plot from CarSim
Because of the minor difference in the constructure and control principle of active and semi-active suspension in reality, semi-active suspension is used to test the performance as an alternative experimental model for active suspension in CarSim. After setting the parameters for the experimental vehicle and simulating two cars on the cross-slope sine sweep test, 3 plots are used as the results: pitch angle of sprung masses, roll angle of sprung masses and vertical acceleration of sprung mass The performance of the semi-active suspension system will be assessed base on the graphs.
The cross-slope sine sweep test has 2 stage of road conditions Firstly, two cars will encounter cross-slope surface, which is used to assess the lateral motion of the vehicle Secondly, the cars will encounter the sine sweep surface after passing the cross-slope surface, which is used to assess the longitudinal motion of the vehicle.
Figure 4 1 Pitch angle of sprung masses
The Figure 4.9 shows the pitch angle of sprung masses between two cars, the blue line represents the result of the passive suspension and the red one represents the semi-active suspension.
When two vehicles encounter the cross-slope disturbance in the first 3 seconds,the blue line shows large and more oscillation than the red line, which mean the semi- active suspension’s pitch angle magnitude is smaller than the passive one After 3 seconds, two cars encounter the sine sweep disturbance It can be seen from the graph that the red line oscillates with smaller pitch angle than the blue line.
Overall, basing on the pitch angle graph, the vehicle body (or sprung masses) of the semi-active suspension car is more stable.
Figure 4 2 Roll angle of sprung masses
The Figure 4.10 shows the roll angle of sprung masses between two cars, the blue line represents the result of the passive suspension and the red one represents the semi-active suspension.
When two vehicles encounter the cross-slope disturbance in the first 3 seconds, both lines experience a large overshoot, because the cross-slope disturbance make the body of the two cars oscillate in lateral direction After 3 seconds, two cars encounter the sine sweep disturbance It can be seen from the graph that both lines stabilize when running on the sine sweep surface.
Overall, basing on the roll angle graph, both vehicles seem to oscillate at the same rate However, after 5 seconds, the semi-active suspension car performs a small stable oscillation compare to the passive one.
Figure 4 3 Vertical acceleration of sprung mass center gravity
The Figure 4.11 demonstrates the magnitude of vertical acceleration of sprung mass center gravity of both vehicles The blue line represents the result of the passive suspension and the red one represents the semi-active suspension.
In overall, the magnitude of the blue line oscillates larger than the red line As can be clearly seen that the passive suspension has the overshoot magnitude about 10 times larger than the semi-active suspension from 6.5 to 7 second According to the previous graphs about the longitudinal and lateral motion of the two sprung masses of both cars, the body of the semi-active suspension car is more stable As a result, the vertical displacement of the vehicle body of the semi-active suspension car is small, so the acceleration of it will have small values too.
In summary, this graduation thesis focused on the modeling, simulation, and assessment of a PID controller-based active suspension system for a half-car model. The objective was to analyze the performance of the active suspension system for half- car model built in Matlab/Simulink and comparation between semi-active and passive suspension systems.
The first step, we have developed a mathematical model of the active suspension system using the PID controller The PID controller parameters were manually tuned based on the progress of expertizing and intuition The half-car model was then simulated using Matlab/Simulink, and various performance metrics were evaluated.
The performance assessment involved plotting displacement of sprung and unsprung masses graph, force graphs, vertical displacement of the vehicle body graph, and pitch angle graph These plots provided insights into the response of the active suspension system under different road conditions By analyzing these graphs, it was possible to assess the effectiveness of the PID controller-based active suspension in reducing vibrations and maintaining stability of the vehicle.
Furthermore, the study also compared the performance of the semi-active with that of the passive suspension system Two cars were simulated, one equipped with a semi-active suspension and the other with a passive suspension The focus was on evaluating the pitch angle, roll angle, and vertical acceleration of the sprung mass for both suspension systems.
The results of the comparison revealed valuable insights The semi-active suspension system demonstrated superior performance compared to passive suspension system It exhibited better control over pitch angle, roll angle, and vertical acceleration, leading to improved ride comfort and stability for the driver This highlighted the significance of employing a PID controller in the active suspension system for effective vibration reduction and enhanced vehicle dynamics.
Overall, this graduation thesis successfully accomplished its objectives of modeling, simulating, and assessing the PID controller-based active suspension system for a half-car model The simulation results and analysis provided valuable insights into the performance of the active suspension system and its superiority over semi- active and passive suspension systems.