Overview of automotive
In modern times, automobiles have become essential for road transportation globally, offering unmatched mobility and versatility They play a vital role in our daily lives by efficiently transporting both passengers and goods Additionally, automobiles are key to national economic growth and contribute significantly to national defense.
The history of automobiles dates back to the 17th century with the initial concept of steam-powered vehicles In 1672, the first steam-powered vehicle was created, but it wasn't until 1769 that Nicolas-Joseph Cugnot designed and built the first steam-powered automobile capable of transporting people This pivotal invention marked the inception of the modern automotive industry.
The 19th century was a pivotal era for automotive innovation, marked by the emergence of groundbreaking inventions like the de Rivas engine, one of the earliest internal combustion engines, and early electric motors Samuel Brown made notable advancements in 1826 by testing the first internal combustion engine for industrial use However, the automobile industry encountered challenges midway through the century due to concerns regarding the large size of vehicles.
Advancements in internal combustion engines, especially those using gasoline, significantly transformed engine technology with the development of two- and four-stroke engines Carl Benz, a key figure in automotive history, was instrumental in this change by introducing the gasoline-powered vehicle and achieving mass production This innovation marked a pivotal moment, leading to the creation of the first practical modern automobile capable of being produced on a large scale.
The Ford Motor Company's introduction of the Model T in 1908 revolutionized the automotive industry by being the first car mass-produced on a moving assembly line This innovation significantly lowered production costs, making automobiles more affordable and accessible to the public The success of the Ford Model T not only transformed transportation but also led to profound social and economic changes.
Since the launch of the Ford Model T, the automotive industry has experienced significant progress in design, technology, and safety features Modern passenger cars are now more refined, efficient, and eco-friendly, thanks to innovations like enhanced engines, hybrid and electric vehicles, advanced safety systems, and autonomous driving technology.
Today’s passenger cars are available in a variety of shapes, sizes, and configurations to cater to the diverse preferences of consumers From compact hatchbacks to luxury sedans, SUVs, and sports cars, the market offers a wide range of options Modern vehicles prioritize comfort and convenience, featuring advanced infotainment systems, connectivity options, and driver-assistance technologies, transforming them into mobile entertainment and communication hubs rather than just a mode of transportation.
Passenger cars are evolving to address global environmental sustainability concerns, with automakers prioritizing the development of electric vehicles (EVs) and enhanced fuel efficiency This shift towards cleaner propulsion systems is transforming the automotive industry and playing a significant role in fostering a greener future.
The evolution of passenger cars has seen significant advancements, transitioning from steam-powered vehicles to today's mass-produced automobiles Innovators such as Carl Benz and the Ford Motor Company have played crucial roles in shaping the automotive industry As technology progresses and sustainability becomes increasingly important, passenger cars are continuously improving in performance, safety, and environmental impact The automobile industry is essential for personal mobility, economic development, and societal progress.
Overview of Camry models of Toyota
The Toyota Camry, introduced in 1982, is a highly regarded mid-size car that has built a significant legacy over the years Known for its outstanding reliability, comfortable ride, and excellent fuel efficiency, the Camry has become one of the best-selling cars globally, earning widespread acclaim and impressive sales figures.
The Toyota Camry lineup offers a variety of models designed to meet different needs and preferences Each model features unique characteristics and specifications, making it essential to explore the distinctive attributes of the entire Camry series.
The Toyota Camry LE, the base model of the series, boasts a 2.5-liter 4-cylinder engine that produces an impressive 203 horsepower It comes equipped with an 8-inch touchscreen infotainment system featuring Apple CarPlay and Android Auto integration, along with advanced safety features that ensure a secure driving experience.
The Toyota Camry XLE enhances the driving experience with its shared engine from the LE model while adding luxurious features such as heated front seats, dual-zone automatic climate control, premium leather upholstery, and an upgraded audio system These sophisticated enhancements elevate comfort and provide an opulent atmosphere for all passengers.
The Toyota Camry SE is an ideal option for drivers looking for a spirited and sporty ride Featuring the same engine as the LE, the SE model enhances performance with a firmer suspension, larger wheels, and a sport-tuned suspension system, resulting in improved handling and a more engaging driving experience Its unique styling elements, including a distinctive black mesh grille and an eye-catching rear spoiler, further set the SE apart from other models.
Taking the sporty essence even further, the Toyota Camry XSE builds upon the
The XSE model builds on the SE by incorporating a variety of enhanced features, including sport front seats and a panoramic sunroof Powered by the same engine as the SE, the XSE also boasts an impressive 9-speaker audio system, creating a premium and immersive driving experience that prioritizes both comfort and entertainment for all occupants.
The Toyota Camry TRD is the standout performance model in the lineup, powered by a formidable 3.5-liter V6 engine that produces an impressive 301 horsepower With features like a lowered suspension, upgraded brakes, and larger 19-inch wheels, the TRD offers an exhilarating driving experience This model is perfect for enthusiasts looking for a dynamic and engaging ride.
In summary, the Toyota Camry series provides a variety of models tailored to meet diverse preferences and needs Whether you're looking for a dependable sedan, a luxurious ride, or a sporty driving experience, the Camry excels in all areas With a strong focus on quality, performance, and customer satisfaction, the Toyota Camry stands out as a top choice for drivers.
Camry continues to dominate the mid-size car segment and captivate drivers worldwide.
Overview of suspension system
Objective of the suspension system
The suspension system in a vehicle is essential for delivering a smooth and comfortable ride, improving stability, and maximizing tire contact with the road Key suspension components are vital in fulfilling these functions by undertaking various important tasks.
The suspension system plays a crucial role in enhancing vehicle comfort by utilizing elastic elements, typically springs, to absorb shocks and vibrations from uneven road surfaces This absorption of dynamic loads not only provides a smoother ride for occupants but also protects the vehicle's frame from excessive stress, ensuring better overall performance and longevity.
The suspension system serves as a crucial guide unit, transferring both longitudinal and transverse forces, along with magnetic moments, from the road to the vehicle chassis Its kinematics enable relative wheel oscillation in relation to the frame, ensuring consistent tire contact with the road surface despite irregularities This functionality significantly improves vehicle stability, handling, and traction, especially during cornering, braking, and acceleration.
Shock absorbers are essential components of a vehicle's suspension system, responsible for dampening vibrations in both suspended and unsuspended parts When driving over bumps or uneven surfaces, the suspension springs initially absorb the impact, but they can cause the vehicle to continue oscillating due to the stored energy Shock absorbers work to dissipate this energy, minimizing the amplitude and duration of these oscillations By effectively managing these movements, shock absorbers enhance ride comfort, stability, and overall vehicle control.
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
The suspension system plays a crucial role in enhancing braking efficiency by ensuring optimal tire contact with the road surface This maintenance of proper traction allows for effective braking and significantly reduces stopping distances.
The suspension system is essential for evenly distributing a vehicle's weight across its tires, which significantly reduces tire wear By ensuring uniform tire contact, it enhances tire longevity and decreases the need for frequent replacements, ultimately saving costs.
In summary, the suspension system in a vehicle is essential for delivering a smooth ride, improving stability, and maintaining optimal tire contact with the road By utilizing elastic components, guide units, and shock absorbers, the system effectively minimizes dynamic loads, manages force transmission, and dampens vibrations This functionality enhances overall vehicle performance, leading to better ride comfort, stability, braking efficiency, and increased tire lifespan.
Requirements of suspension system
An active suspension system in a vehicle should have the following requirements:
An active suspension system must be adjustable to accommodate various driving conditions and individual driver preferences This adjustability enables the driver to modify key elements such as damping force, spring stiffness, and ride height, optimizing both ride quality and handling for different loads and driving styles.
An active suspension system significantly enhances ride comfort by efficiently absorbing road irregularities and dampening vibrations, resulting in a smoother experience for passengers This improved ride quality reduces fatigue and contributes to a more enjoyable driving experience.
An active suspension system enhances vehicle handling, steering, and stability by individually adjusting suspension dampening and ride height for each wheel based on dynamic conditions This technology improves grip and control, minimizes body roll during cornering, and delivers a more stable driving experience.
An active suspension system provides rapid responses to changing road conditions and driving demands by utilizing sensors and electronic control units This constant monitoring enables the system to swiftly adjust the damping force, enhancing vehicle control and allowing for immediate adaptation As a result, optimized performance, improved handling, and increased safety are achieved.
Active suspensions utilize variable damping to deliver adjustable damping force tailored to specific conditions Unlike passive suspensions with fixed damping, these systems electronically modify the damping characteristics based on factors such as speed, load, road conditions, and driver input This adaptability enhances performance across diverse scenarios, ensuring optimal handling without compromise Variable damping is essential for realizing the advantages of active suspension systems.
Structure of suspension system
The elastic component of a vehicle plays a crucial role in enhancing wheel oscillation, aligning the vehicle's oscillation frequency with the optimal range for user comfort This ensures a smooth ride while effectively supporting the vehicle's weight.
• 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
Automobile applications utilize various suspension systems, such as independent suspension, dependent suspension, torsion bar suspension, and air suspension Each system offers unique advantages and disadvantages, making the selection process dependent on the specific needs of the vehicle.
Suspension systems can be categorized based on their construction and application, with the two primary types being dependent and independent systems In a dependent suspension system, both wheels share the same axle, causing any movement or shock experienced by one wheel to affect the other In contrast, an independent suspension system allows each wheel to move independently, resulting in reduced transfer of movement between them Various designs of independent suspension systems, including double-wishbone and multi-link configurations, offer unique benefits and characteristics.
The wheels are mounted on a single bridge girder that connects to the car's body, making this suspension system particularly suitable for heavy vehicles due to its remarkable durability However, when the vehicle is unloaded, this mechanism can become overly rigid, leading to reliability issues and increased susceptibility 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
Twist-beam suspension is a cost-effective solution commonly found in smaller vehicles, designed to provide an optimal balance between handling and ride comfort This system features a solid beam with a pivot joint at its center, linking the rear wheels for enhanced stability and performance.
− Advantages of Twist-beam suspension:
Twist-beam suspension systems are generally more affordable to develop, produce, and maintain compared to other suspension types, making them an attractive option for automakers focused on compact or budget-friendly 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
Twist-beam suspensions provide enhanced handling over traditional live-axle suspensions by reducing the unsprung mass at the rear wheels, which improves traction on the road.
− Disadvantages of Twist-beam suspension:
Twist-beam suspension systems offer limited shock absorption compared to more advanced options such as independent rear suspension or multi-link suspension Consequently, this can lead to a less comfortable ride, particularly on uneven or bumpy surfaces.
• 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
Solid axle suspension, commonly seen in larger vehicles such as trucks and SUVs, features a single beam that connects the wheels and spans the vehicle's width This design supports the vehicle's weight using coil or leaf springs, offering a robust and durable suspension system.
− Advantages of solid axle suspension:
Solid axle suspension systems are celebrated for their exceptional durability and ability to handle heavy loads They offer superior resistance to damage from stones and debris, making them well-suited for challenging terrains.
• 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:
Solid axle suspensions lack the responsiveness and control found in more advanced suspension systems, resulting in a rougher and less enjoyable ride, particularly on rocky terrain.
Uneven weight distribution, often stemming from the solid axle connection in smaller cars, can significantly affect handling during cornering This imbalance may lead to stability issues, particularly at high speeds, compromising overall driving performance.
• Reduced fuel efficiency: As solid axle suspension systems are often heavier than other kinds of suspension systems, their fuel efficiency may suffer
The vehicle's wheels are mounted independently, allowing each wheel to move freely in any direction without being linked to the others This design enhances maneuverability and flexibility in handling.
The independent suspension system features a more complex design compared to the dependent suspension system, providing vehicles with superior traction and enhanced mobility This technology allows for a lower chassis construction, eliminating the need for bridge girders.
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):
The system comprises three essential components: hydraulic shock absorbers, springs, and steering arms, which streamline the attachment points to the chassis from four to two The shock absorber serves as the guiding element, connecting to a single bar, while the lower crossbar is linked to the wheel hub.
The MacPherson suspension system features a streamlined design that accelerates assembly, reduces production costs, and minimizes weight, all while optimizing space in the compact engine compartments of front-wheel drive vehicles Additionally, it simplifies repairs and maintenance, making it the most widely used suspension type in automobiles.
• 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 are essential for enhancing comfort, stability, and handling in vehicles The evolution of suspension technology has led to three primary types: passive, semi-active, and active suspensions Each type offers unique characteristics that significantly impact ride quality, handling, and adaptability to different road conditions.
Passive suspensions are the most traditional type used in vehicles, featuring mechanical components like coil springs and hydraulic shock absorbers These systems do not actively adjust their characteristics; instead, they depend on the inherent properties of their components Coil springs offer vertical support, influencing the vehicle's ride height and load-carrying capacity, while hydraulic shock absorbers, or dampers, manage suspension movement by dissipating energy from road disturbances.
Passive suspensions are an economical and straightforward choice for vehicles, featuring fixed characteristics that do not adjust in real-time While they strike a balance between ride comfort and handling—often leaning towards comfort—these systems can struggle to perform optimally under varying road conditions and vehicle dynamics, limiting their adaptability to changing environments.
Semi-active suspensions serve as a middle ground between passive and active suspension systems They feature electronically controlled dampers that can dynamically adjust their damping characteristics in real-time By utilizing sensors to track key vehicle parameters like wheel acceleration, body roll, and road conditions, these dampers enable adaptive responses for improved ride quality and handling.
Semi-active suspensions enhance ride comfort and handling by adjusting damping forces to suit varying road conditions, effectively reducing excessive body movements These systems provide multiple modes, enabling drivers to select between comfort-focused or sportier settings according to their personal preferences.
Semi-active suspensions, while offering a balance of cost, performance, and adaptability, have limitations compared to fully active systems They lack the ability to adjust suspension parameters like spring rates and ride height actively, and their response time and adjustability may not match the precision of active suspensions.
Active suspensions are the forefront of suspension technology, delivering exceptional control and adjustability By employing sophisticated electronic control units, sensors, and actuators, these systems dynamically modify various suspension parameters in real-time, enhancing vehicle performance and ride quality.
Active suspensions dynamically adjust damping forces, spring rates, and ride height in response to factors like road conditions, vehicle speed, steering angle, and acceleration This continuous monitoring and adjustment enable active suspensions to deliver optimal performance in diverse driving situations, enhancing ride comfort, stability, and handling.
Active suspensions offer numerous advantages, including the reduction of body roll during cornering, the minimization of dive and squat during acceleration and braking, and enhanced traction by adapting to varying road conditions Additionally, the effectiveness of active suspensions can be significantly improved with the integration of road preview systems, which proactively adjust the suspension in anticipation of road irregularities.
Automotive suspension systems are primarily categorized into three types: passive, semi-active, and active Passive suspensions, the most prevalent, strike a fixed balance between comfort and handling In contrast, semi-active suspensions enhance ride quality and handling through adaptive damping Active suspensions represent the forefront of technology, dynamically adjusting parameters for optimal performance across diverse driving conditions Each type offers distinct advantages and limitations, with the choice influenced by cost, performance needs, and driver preferences As technology evolves, future advancements are expected to enhance control and adaptability in 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 is the most complex option available in the market, featuring numerous parts and intricate systems This model includes all components found in a half-car suspension while also integrating the vehicle's dynamic properties and suspension geometry to precisely represent its behavior in 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 effectively models a vehicle's weight, encompassing crucial components like the wheels, brakes, and suspension parts that lack spring support.
The tire component in the full suspension model is a masterpiece, expertly managing lateral, longitudinal, and vertical forces while taking into account factors such as slip angle, camber angle, and rolling radius.
The full suspension model features a comprehensive steering and braking system, incorporating intricate components like the steering mechanism, steering gear, steering linkage, brake calipers, brake pads, rotors, and hydraulic lines.
The full suspension system model equips engineers with a robust tool for optimizing and evaluating the intricate dynamics and designs of vehicle components, ensuring superior ride quality, handling, and stability Additionally, this model allows for the analysis of external factors, including road conditions and vehicle speed, and their impact on the overall efficiency of the suspension system.
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 an efficient tool commonly used in engineering analyses to simulate and control suspension systems It focuses on the vertical dynamics of a single tire, making it simpler and more practical than the half-car model.
This innovative model is named for its emphasis on a single wheel and its associated suspension elements, featuring a surprisingly simple assembly of essential 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 utilize the quarter-car model to evaluate suspension system effectiveness by analyzing wheel movement under driving conditions, particularly how road bumps affect wheel motion relative to the vehicle body By adjusting parameters like the damping coefficient and spring constant, they can identify the optimal suspension setup for enhanced ride comfort and handling performance Additionally, the quarter-car model serves as an effective method for assessing various suspension systems, including passive, semi-active, and active configurations.
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:
𝐹 𝑎 - Actuator force of active suspension system
The control equation for pitch moment as followed:
𝜃̈ 𝑠 - Rotary angle at vehicle’s center of gravity
𝐿 𝑓 , 𝐿 𝑟 - 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:
𝑚 𝑢𝑓 - Vehicle body unsprung mass at front
𝑍̈ 𝑢𝑓 - Acceleration of unsprung mass at front
𝑘 𝑡𝑓 - 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:
𝑳 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 half-car model is a simplified vehicle representation commonly utilized in the research and design of automobile suspension systems This model effectively bridges the gap between basic vehicle dynamics analysis and more complex suspension studies, making it a valuable tool in automotive engineering.
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 half suspension model enables engineers to analyze the interaction between a vehicle's suspension system and the road surface, providing insights into handling, stability, and ride quality This model is instrumental in testing various suspension configurations and design elements, including spring rates and damper settings, to enhance ride comfort and overall handling performance.
Introduction to matlab/Simulink
MATLAB/Simulink is a powerful combination of tools designed for numerical computation and simulation MATLAB serves as a high-level programming language and interactive environment, ideal for data analysis, visualization, and numerical tasks In contrast, Simulink provides a graphical programming environment for modeling, simulating, and analyzing dynamic systems This software is particularly valuable in industries such as automotive, aerospace, and communication, where it is used to design and test complex control and signal processing systems Together, MATLAB and Simulink deliver 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 the MATLAB environment, numerous functions enable engineers and users to perform matrix and array mathematics effortlessly, without needing programming experience Basic mathematical functions can be executed through simple commands, which can then be scaled up to develop large-scale applications.
Graphics is a crucial feature of Matlab, enabling users to visualize data through graphs Engineers can create tailored graphics and interactive elements, enhancing their data presentation Additionally, Matlab allows for saving visualizations in various formats, including PDF, EPS, and PNG, facilitating easy sharing and exporting of graphical content.
Matlab's support for app builders focuses on two key tasks: designing the graphical user interface (GUI) layout and programming the app's behavior These functionalities are already integrated into Matlab’s library, which includes a variety of standard components such as buttons, checkboxes, and tables.
MATLAB and Simulink application deployment products allow engineers and scientists to securely share their work as standalone applications, web apps, Docker containers, and more with unlicensed users, including collaborators and clients.
Leveraging MATLAB and Simulink in the cloud accelerates development for engineers and scientists by offering instant access to advanced computing resources, essential software tools, and dependable data storage solutions.
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 powerful and flexible platform for developing and implementing deep learning models across diverse fields It offers an extensive range of functions and toolboxes that simplify the process of building, training, and analyzing deep learning models.
Introduction to CarSim
CarSim is a powerful simulation software designed to model the dynamic behavior of cars and light trucks It accurately captures vehicle mechanics in response to driver inputs or automated controls, including steering, throttle, braking, and gear shifting, through advanced 3D multibody dynamics models The software also incorporates realistic environmental factors, such as 3D ground and road surfaces, as well as the effects of aerodynamics and wind.
CarSim has been extensively validated and correlated with real-world outcomes, as confirmed by various automotive OEMs globally The underlying technology behind CarSim is known as VehicleSim, which serves as its foundational framework.
"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, such as those provided by CarSim, eliminate the need for intricate knowledge of component materials and suspension details, allowing for straightforward measurement and computation of vehicle data These models enable the simulation of physically measurable reactions, ensuring repeatability through comprehensive mathematical representation of vehicle dynamics To achieve accurate simulations, essential information regarding kinematics, suspension compliance, tire force characteristics, and environmental factors is required Despite potential gaps in reference data, these mathematical models yield representative results that are effective for evaluating various vehicle designs and control strategies.
CarSim defines a parametric vehicle by utilizing a combination of parameters and variables that represent quantifiable attributes such as size and inertia Configurable Functions in CarSim leverage various extrapolation and interpolation techniques to associate model variables with linear coefficients or tables Additionally, several tables include data derived from tire and suspension test rigs, while other nonlinear relationships, including friction and road geometry, can be easily imported from spreadsheets and are represented in a tabular format.
Figure 3 5 Parametric and tabular data used in CarSim
ADAS and AV Support: To mimic scenarios involving Advanced Driver
Assistance Systems (ADAS) and autonomous vehicles utilize CarSim to simulate moving target objects, including traffic vehicles, pedestrians, and bicycles Virtual sensors within the system detect these targets, producing 24 computed output variables for each possible sensor-target detection pair.
CarSim offers nearly 600 sample simulations featuring various automobiles and a range of test scenarios These simulations include approximately 40 sample vehicles, showcasing at least 10 distinct vehicle configurations, providing users with a comprehensive resource for vehicle dynamics analysis.
The VS Browser, a Graphical User Interface (GUI) for Windows, allows users to launch CarSim, configure settings, and view results It displays various vehicles, environments, and processes, all linked to a database of relevant data Each screen includes a Help button that provides a detailed description of its functions and options The Help drop-down menu offers access to technical documents, reference materials, and tutorials, all organized in a searchable Help folder compatible with Adobe Reader Users can easily refer to documentation, such as the CarSim Quick Start Guide, through the Help menu under Guides and Tutorials.
CarSim features the VS Visualizer, a powerful tool that generates high-quality animations of simulation results alongside engineering charts displaying hundreds or even thousands of variables from the mathematical model This synchronization of charts and video enhances the analysis of both qualitative and quantitative data, while the capability to overlay up to six different runs allows for effective comparisons between various vehicle and control combinations.
Figure 3 6 Viewing synchronized video and plot of CarSim vehicle with VS Visualizer
Fast calculations in CarSim simulations can complete a 60-second test in just 3 to 4 seconds on a modern Windows machine, thanks to its highly optimized math model, which operates 15 to 20 times faster than real-time Even under heavy loads, such as multiple moving objects and extensive data storage, the simulations maintain a speed that surpasses real-life performance.
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
When using CarSim with the Browser and VS Visualizer on Windows, you can leverage essential functionalities for various applications The software allows you to review the data used in simulations and analyze the outcomes of past simulations Additionally, you can create new instances by duplicating and modifying existing simulations, utilizing pre-defined car models for your projects.
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)
Below the navigation bar, users will find a row of buttons, including the Duplicate button (3) for copying the existing dataset, which can then be modified for new data Editable text locations are highlighted with a yellow backdrop (9) when the dataset is unlocked Additionally, the Sidebar button (8) allows users to show or hide a section on the left that contains optional comments (4) about the current dataset and a tree representation of the simulation.
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
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 features customizable blue hyperlinks similar to those found in web browsers, enhancing user interaction When hovering over these blue links, the text is emphasized, mirroring the behavior of web links Clicking on a blue link from the Run Control screen will display the associated vehicle's datasheet for assembly.
The hyperlink control can be expanded in two distinct ways using the associated drop-down controls For instance, the blue link located in the top left corner of the screen enables you to specify the vehicle's sprung mass, as illustrated in Figure 3.11.
Figure 3 11 A Vehicle: Assembly dataset used in the example simulation setup
Figure 3 10 Blue link to another dataset
Figure 3 12 Libraries available for a blue link
Access the Sprung Mass screen and its dataset by clicking the blue Sprung Mass link Use the drop-down menu at the top to select a database library This example shows how CarSim can present Sprung Mass statistics in two formats: Sprung Mass and Sprung Mass (from Whole Vehicle) Choose between these two libraries using the top control.
Clicking the drop-down menu next to the blue link reveals all datasets available in the selected library Users can choose any dataset by selecting its name from this menu or can duplicate an existing dataset to create a new one that can be modified as needed.
Figure 3 13 Datasets in the linked library
Graphs plot from Matlab/Simulink
We successfully modeled a PID Controller-based Active Suspension system for a half car model, showcasing the effectiveness of control forces generated by actuators The resulting graphs illustrate the theoretical operation of the PID control in counteracting the forces acting on the vehicle's sprung mass.
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
As the vehicle approaches the test road at time t = 0, the front suspension begins to rise in response to the road's bumps, with the displacement corresponding to the height of each bump Throughout the simulation, the front suspension continues to oscillate in an upward and downward motion, mirroring the pattern of a sine wave until the end of the test.
The rear suspension experiences a two-second delay in signal response based on the model's settings, leading to oscillations during this waiting period due to the front suspension's impact When the front suspension moves upward from road forces, it generates a torque at the top of the half-car model, resulting in a pitching moment that explains the oscillation of the rear suspension Once the rear suspension receives the sine wave signal, it mirrors the front suspension's displacement until the simulation concludes.
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
The blue line, represented by F_sf, initially exhibits an overshoot before stabilizing at the 4th second From the 5th second onward, the force magnitude remains constant throughout the remainder of the simulation.
• The Figure 4.4 shows the force acts on the rear vehicle being represented by
The blue line, representing Fsr, indicates that when the front vehicle first receives the signal, a pitch moment occurs due to the displacement of the rear unsprung mass This initial signal generates a force acting on the rear before it has received the signal itself Once the rear vehicle does receive the signal, it experiences an overshoot, causing the force to oscillate rapidly for approximately two seconds before stabilizing and maintaining a consistent magnitude for the remainder of the simulation.
Both suspensions utilize a PID controller to manage the force actuator, as illustrated by the red line in the graphs, which depicts the force generated to counteract the force from the unsprung mass Notably, the magnitude of these actuator forces is entirely opposite to the forces represented by the blue line.
The force generated by the actuator is influenced by the analysis and adjustments of the PID controller, resulting in an output force that is opposite in direction but not equal in magnitude Despite these model limitations, the generated force can still be accepted and utilized to effectively control the final force acting on both the front and rear of the vehicle.
Figure 4.5 Force acting on front vehicle body
Figure 4.6 Force acting on rear vehicle body
In Figures 4.5 and 4.6, the blue line illustrates the force responsible for the vehicle's displacement, while the red line represents the same force that is countered by the actuator's force This results in a final force acting on the vehicle, which is intentionally minimized to reduce displacement during road movement.
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
Despite the significant final force, both the front and rear of the vehicle experience ongoing forces Initially, when the vehicle receives a signal, there is a delay in feedback processing, which is necessary for the PID controller to analyze the error and determine the appropriate canceling force This feedback loop requires a brief period to establish a complete signal flow While the rear vehicle also experiences force at the onset, the pitch moment force is relatively small compared to the initial sine wave signal This discrepancy helps explain why the final force on the rear vehicle does not fully eliminate the overshoot, even after accounting for errors during the waiting period.
Figure 4.7 illustrates the vehicle's pitch angle during simulation, revealing that the pitch angle is minimal This suggests that the vehicle does not exhibit significant rotation, leading to the conclusion that there is no notable rotation occurring.
Figure 4.8 The displacement of vehicle body
At the conclusion of the simulation, we analyze the vertical motion of Z, which is the primary objective of this model The active suspension system aims to negate all forces acting on the vehicle, ensuring that the vehicle body remains stable while traversing various road conditions In Figure 4.8, the red line illustrates the displacement of Z, corresponding to the movement of the 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
The final results align with the initial goals set by our team for the project, focusing on developing a model to achieve these objectives While the theory of the active suspension system has been constructed using Simulink to illustrate its functionality, the project lacks practical experience with a real model, limiting its ability to demonstrate the optimal performance of the active suspension system in real-world applications.
Graphs plot from CarSim
Semi-active suspension serves as an alternative experimental model for active suspension in CarSim due to their minor differences in construction and control principles After configuring the parameters for the experimental vehicle and conducting a cross-slope sine sweep test with two simulated cars, three key performance metrics are analyzed: the pitch angle of sprung masses, the roll angle of sprung masses, and the vertical acceleration of sprung mass The evaluation of the semi-active suspension system's performance is based on these graphical results.
The cross-slope sine sweep test evaluates vehicle dynamics through two distinct stages of road conditions Initially, vehicles traverse a cross-slope surface to analyze their lateral motion Following this, the cars encounter a sine sweep surface, which is designed to assess their longitudinal motion.
Figure 4 1 Pitch angle of sprung masses
Figure 4.9 illustrates the pitch angle of sprung masses between two vehicles, with the blue line indicating the performance of passive suspension and the red line representing the semi-active suspension system.
In the initial 3 seconds of encountering cross-slope disturbances, the semi-active suspension (blue line) exhibits greater oscillations compared to the passive suspension (red line), indicating a smaller pitch angle magnitude for the semi-active system After this period, when both vehicles face sine sweep disturbances, the graph reveals that the passive suspension (red line) maintains a smaller pitch angle than the semi-active suspension (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
Figure 4.10 illustrates the roll angle of sprung masses between two vehicles, with the blue line indicating the performance of passive suspension and the red line depicting the results of semi-active suspension.
During the initial 3 seconds of encountering a cross-slope disturbance, both vehicles exhibit significant overshoot due to lateral oscillations Following this period, the cars experience a sine sweep disturbance, after which the data indicates that both vehicles stabilize while navigating the sine sweep surface.
Based on the roll angle graph, both vehicles exhibit similar oscillation rates initially However, after 5 seconds, the semi-active suspension car demonstrates a small, stable oscillation, in contrast to the performance of the passive suspension vehicle.
Figure 4 3 Vertical acceleration of sprung mass center gravity
Figure 4.11 illustrates the vertical acceleration magnitude of the sprung mass center of gravity for both vehicles, with the blue line indicating the performance of the passive suspension system and the red line representing the semi-active suspension system.
The blue line exhibits a significantly larger oscillation magnitude compared to the red line, with the passive suspension demonstrating an overshoot magnitude approximately ten times greater than that of the semi-active suspension between 6.5 to 7 seconds Previous graphs indicate that the body of the semi-active suspension vehicle is more stable, resulting in minimal vertical displacement and consequently lower acceleration values.
This graduation thesis presents a comprehensive analysis of a PID controller-based active suspension system for a half-car model, utilizing Matlab/Simulink for modeling and simulation The primary objective is to evaluate the performance of this active suspension system and to compare its effectiveness against semi-active and passive suspension systems.
We developed a mathematical model of an active suspension system utilizing a PID controller, with parameters manually tuned through expert insights and intuition The half-car model was subsequently simulated in Matlab/Simulink, allowing for the evaluation of various performance metrics.
The performance assessment of the active suspension system was conducted through detailed graphing of the displacement of sprung and unsprung masses, force dynamics, vertical displacement of the vehicle body, and pitch angle variations These graphical representations offered valuable insights into the system's response across various road conditions Analyzing these plots enabled a thorough evaluation of the PID controller's effectiveness in minimizing vibrations and ensuring vehicle stability.
The study compared the performance of semi-active and passive suspension systems by simulating two cars: one with semi-active suspension and the other with passive suspension The evaluation focused on key metrics such as pitch angle, roll angle, and vertical acceleration of the sprung mass for both systems.
The comparison results highlighted the advantages of the semi-active suspension system over the passive suspension system, showcasing improved control of pitch angle, roll angle, and vertical acceleration This enhancement leads to greater ride comfort and stability for the driver, emphasizing the importance of integrating a PID controller in the active suspension system for effective vibration reduction and optimized vehicle dynamics.
This graduation thesis effectively achieved its goals by modeling, simulating, and evaluating a PID controller-based active suspension system for a half-car model The simulation results highlighted the active suspension system's performance, demonstrating its advantages over both semi-active and passive suspension systems.