Feedback control systems for d.c. electromagnets in passenger-carrying vehicles

The vehicle suspension system serve a dual purpose – to provide passenger comfort and good road holding. In the design of a vehicle suspension system, these two contradictory criteria must be balanced out. Road irregularities are also a major source of anxiety amongst drivers and passengers alike. This research was undertaken to investigate the effect road irregularities will have on the vehicle structure especially the suspension system. In this study, the responses of different linear vehicle models are studied for step road input. The mathematical models considered are: a two degrees-of-freedom system (quarter car model) and a four degrees-of-freedom system (half car model). The equations of motion for both models were obtained using Newton’s method. These models are analysed using SIMULINK/Matlab. Different response parameters such as the acceleration of the vehicle body and the travel of the suspension are investigated for a passive suspension system. The responses of the vehicle suspension due to changes in parameters such as suspension stiffness and damping coefficients are investigated. The results show that road irregularities affect the vehicle structures and the response of the suspension system is dependent on the suspension parameters. Passive suspension systems do not satisfy road holding and passenger comfort at the same time.

Abstract: Suspension systems are integral to vehicle performance, playing a critical role in enhancing ride comfort, stability, and handling. By absorbing shocks and vibrations, suspension systems ensure a smoother ride for occupants, improve traction, and maintain optimal tire contact with the road. Effective suspension systems also contribute to overall vehicle safety by optimizing braking performance and manoeuvrability. In this research paper, we explore the design and analysis of electromagnetic suspension systems, focusing on their application in automotive engineering. The suspension system plays a critical role in providing passenger comfort, isolating occupants from road noise, bumps, and vibrations, and maintaining chassis stiffness. As vehicles evolve, the demand for sophisticated suspension systems that balance ride comfort, stability, and safety becomes increasingly important

Suspension is one of the most important assemblies in modern automobile. The performance of suspension determines the whole vehicle performance, so the design and optimization of suspension system is an important part of automobile overall design. Under the background of the China University formula car race, this paper takes the suspension system of the University formula car designed by the team as the research object, and mainly carries out the following research work: 1, The type of suspension is determined by comparing the advantages and disadvantages of the structure; 2. Parameter design of the suspension, including the selection of wheel alignment parameters, suspension geometry drawing, various stiffness calculation, damping coefficient calculation, etc.; 3. According to the results of parameter design, the design and assembly of various parts of the suspension system are carried out; 4. Based on ADAMS / car simulation platform, The kinematics simulation model of the front and rear suspension is established, and the simulation analysis of the model is carried out to find out the variation range of parameters and find out the unreasonable performance parameters, which directly affects the handling stability and ride comfort of the racing car, so the reasonable design of the suspension system is of great significance to improve the performance of the formula racing car. To sum up, in order to improve the driving stability of formula racing car and make it have the appropriate ability of vibration attenuation, this paper designs the suspension system based on the third spring structure. This makes the structure of suspension linear stiffness and roll stiffness decoupled, so as to ease the contradiction between handling stability and ride comfort, so as to achieve the purpose that the third spring and lateral stabilizer bar manage the linear stiffness and roll stiffness respectively. Adams / car is used to simulate the dynamics of formula racing car. The results show that the third spring can increase the vertical stiffness and has little effect on the roll stiffness when the wheel jumps in the same direction. However, the influence on the body roll can be ignored in the process of acceleration and braking, but it can effectively inhibit the acceleration and braking. The simulation results show that the third spring can effectively improve the longitudinal performance of the vehicle. The method and experience can provide inspiration and method for the design of the suspension system of formula racing car.

The optimal control design of the ground-vehicle active suspension system is presented. The active suspension system is to improve the vehicle ride comfort by isolating vibrations induced by the road profile and vehicle velocity. The vehicle suspension system is approached by a quarter car model. Dynamic equations of the system are derived by applying Newton’s second law. The control law of the active suspension system is designed using linear quadratic regulator (LQR) method. Performance evaluation is done by benchmarking the active suspension system to a passive suspension system. Both suspension systems are simulated in computer. The simulation results show that the active suspension system significantly improves the vehicle ride comfort of the passive suspension system by reducing 50.37% RMS of vertical displacement, 45.29% RMS of vertical velocity, and 1.77% RMS of vertical acceleration.

The stability of vehicles is influenced by the suspension system. At present, there are many studies on the suspension of traditional passenger vehicles, but few are related to agricultural mobile robots. There are structural differences between the suspension system of agricultural mobile robots and passenger vehicles, which requires structural simplification and modelling concerning suspension of agricultural mobile robots. This study investigates the optimal design for an agricultural mobile robot’s suspension system designed based on a double wishbone suspension structure. The dynamics of the quarter suspension system were modelled based on Lagrange’s equation. In our work, the non-dominated sorting genetic algorithm III (NSGA-III) was selected for conducting multi-objective optimization of the suspension design, combined with the Technique for Order Preference by Similarity to the Ideal Solution (TOPSIS) to choose the optimal combination of parameters in the non-dominated solution set obtained by NSGA-III. We compared the performance of NSGA-III with that of other multi-objective evolutionary algorithms (MOEAs). Compared with the second-scoring solution, the score of the optimal solution obtained by NSGA-III increased by 4.92%, indicating that NSGA-III has a significant advantage in terms of the solution quality and robustness for the optimal design of the suspension system. This was verified by simulation in Adams that our method, which utilizes multibody dynamics, NSGA-III and TOPSIS, is feasible to determine the optimal design of a suspension system for an agricultural mobile robot.

Roadway rumble strips are used to reduce driving comfort and make drivers decelerate. While vehicle suspension systems are designed for passengers’ comfort by absorbing vibrations caused by bumping roadway surface, roadway rumble strips are implemented to alert motorists to reduce speed. An efficient and safe roadway rumble strips design depends on the understanding of the vehicles’ suspension system. Newer marked vehicles always have better suspension system that can absorb higher vibrations. This paper investigates the relationship between vehicle suspension system and roadway rumble strips design through TruckSim, a computer simulation model for trucks. The study analyzes the various shock-absorbing effect of current popular vehicle suspension systems on the roadway rumble strips designs in order to evaluate roadway rumble strips effectiveness in speed reduction. BACKGROUND There were 265,204 auto accidents in China in 2008. The direct financial cost of these crashes was more than 1.01 billion Yuan. 73,484 people were killed and 304,919 people injured. Speeding-related crashes account for over 10.17% of these auto accidents. 14.40% of killed people, 9.44% of injured people and 10.59% of the direct financial cost of these crashes (M.P.S., 2008). Speeding is thus a danger to all road users. When researchers do their best for the improvement of the road safety, many new methods and facilities are raised for application. Roadway rumble strips are a speed limit feature for road safety and have an extensive application on the freeway with sharp curves or long steep slopes. This article analyzes accelerations of seat surface when trucks with different suspension systems pass over different roadway rumble strips.

The purpose of the paper is to study the design of the active wheel suspension system. The goal of the control design is the disturbance attenuation with respect to the road disturbances when some of the physical parameters of the system are uncertain. On the basis of a linear quarter-car model the tire stiffness and suspension stiffness are assummed to be uncertain. In this paper the authors deal with some new robust design methods. They examine the applicability of H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> control in case of the active suspension system using a quarter-car model. The problem is solved as a direct state-feedback H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> control problem and in case of structured uncertainties as an RLQR (Robust LQR) design task. On the basis of combination of these two methods new procedure is proposed.

&lt;div class="htmlview paragraph"&gt;The existing vehicle designs exhibit a high level of coupling. For instance the coupling in the suspension and steering systems manifests itself through the change in wheel alignment parameters (WAP) due to suspension travel. This change in the WAP causes directional instability and tire-wear. The approach of the industry to solve this problem has been twofold. The first approach has been optimization of suspension link lengths to reduce the change in WAP to zero. Since this is not possible with the existing architecture, the solution used is the optimization of the spring stiffness K to get a compromise solution for comfort (which requires significant suspension travel and hence a soft spring) and directional stability (which demands least possible change in wheel alignment parameters and hence a stiff spring).&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;This paper presents an axiomatic design solution to this problem and an attempt to remove the coupling in the steering and suspension systems by making the WAP independent of suspension travel. The four-bar linkages used in the existing independent suspension systems are incapable of satisfying their FRs and cause coupling at a higher level. The proposed solution uses a six-bar Watt-I linkage suspension, which removes the coupling. It offers other advantages like the &lt;i&gt;hardening characteristics&lt;/i&gt; for the suspension. A new steering system conformal to the new suspension system has been proposed.&lt;/div&gt; &lt;div class="htmlview paragraph"&gt;FR/DP decomposition of the vehicle systems is presented. This indicates other couplings and DP redundancies in the vehicle system and also provides the framework for design of novel vehicles.&lt;/div&gt;

Vehicle suspension systems often exhibit nonlinear characteristics, particularly due to hardening stiffness. However, traditional modeling strategies usually neglect this nonlinearity, leading to inaccuracies in predicting chassis behavior under varying road excitations. To enhance the understanding of nonlinear chassis dynamics, this study examines the influence of suspension stiffness nonlinearity on the dynamic characteristics of the vehicle chassis under harmonic road excitation. In this work, the Craig-Bampton component mode synthesis (CB-CMS) method is employed to reduce the finite element model of the chassis structure. To incorporate nonlinear characteristics into the reduced order model, the degrees of freedom associated with the nonlinear suspensions are retained during the CB-CMS reduction process. This allows for efficient parametric analysis of stiffness nonlinearity directly within the same reduced order model, eliminating the need to repeat the model reduction process. The effects of stiffness nonlinearity on the vehicle dynamics and chassis vibration are investigated using the proposed modeling approach. Numerical results demonstrate that a chassis system with a higher degree of hardening suspension stiffness exhibits a lower resonance frequency and reduced vibration amplitude. The proposed modeling approach enables efficient analysis of nonlinear suspension effects on flexible chassis models, which has often been treated as a rigid body in previous research.

This paper proposes a new type of a direct-drive valve (DDV) suspension system for vehicle controlled by the piezostack actuator associated with displacement amplifier. In order to achieve this goal, a new type of controllable piezostack DDV damper is designed and its performance evaluation of damping force is undertaken. Next, a full vehicle suspension system consisting of sprung mass, spring, tire and the piezostack DDV damper is constructed. After deriving the governing equations of the motion for the proposed the piezostack DDV suspension system, the skyhook controller is implemented for the realization of the full vehicle. Analytical model of the whole suspension system is then derived and performance characteristics are analyzed through numerical simulation. Finally, vibration control responses of the vehicle suspension system such as vertical acceleration are evaluated under both bump and sine road conditions.

In order to study the influence of heavy truck dynamic parameters on the vehicle’s ride comfort under the random road excitation, the weighted RMS (root-mean-square) acceleration responses of the vertical driver’s seat and cab pitch angle are chosen as objective function, a dynamic model of the vehicle with 10 degrees of freedom is established to simulate and analyze the results. The influence of different parameters of all the suspension systems of the vehicle, such as the stiffness and damping of the suspensions of the seat, cab, vehicle, and wheel, on the vertical driver’s seat and cab pitch angle are respectively analyzed. The study results show that the influence of the stiffness and damping parameters in the suspension systems on the vehicle ride comfort is very obvious. The vehicle’s ride comfort changes worse with the increase of the suspension stiffness and the reduction of the suspension damping, and vice versa. The study proposes an optimal range of the stiffness and damping parameters for the optimal design and control of the vehicle suspension systems, concurrently, the study can also provide a theoretical basis for the suspension system designed for heavy trucks.

Additive manufacturing (AM) technologies provide the possible method to manufacture the new suspension for ultra-weight green vehicles. In spite of traditional suspension system with a large amount of small components, Additive Manufacturing technologies allow the manufacturers to manufacture complicated mechanical structure in single piece which could efficiently decrease the number of components, the mass of new suspensions and the time for assembling. With the support of the modelling software, such as Creo® and AutoCAD®, the design concepts can be easily presented departments and made modifications when it is necessary. Finite element analysis software, such as ANSYS®, will provide the platform to do structural analysis by simulation without physically making the prototypes. Integrating these tools and technologies, time for products development will be dramatically reduced and ready-to-make products can be achieved. In this research, various concepts of the wishbones for the new suspension system will be designed based on the design constraints and the new designs will then be analysed by finite element analysis (FEA) in terms of stress distribution and total deformation of the model under a defined load. Creo® will be used to create the models of wishbones and ANSYS Workbench® will be employed for the structural analysis. Prototypes will also be built by Selective laser melting (SLM).Additive manufacturing (AM) technologies provide the possible method to manufacture the new suspension for ultra-weight green vehicles. In spite of traditional suspension system with a large amount of small components, Additive Manufacturing technologies allow the manufacturers to manufacture complicated mechanical structure in single piece which could efficiently decrease the number of components, the mass of new suspensions and the time for assembling. With the support of the modelling software, such as Creo® and AutoCAD®, the design concepts can be easily presented departments and made modifications when it is necessary. Finite element analysis software, such as ANSYS®, will provide the platform to do structural analysis by simulation without physically making the prototypes. Integrating these tools and technologies, time for products development will be dramatically reduced and ready-to-make products can be achieved. In this research, various concepts of the wishbones for the new suspension system wil...

Comfort, road holding and safety of passenger cars are mainly influenced by an appropriate design of suspension systems. Improvements of the dynamic behaviour can be achieved by implementing semi-active or active suspension systems. In these cases, the correct design of a well-performing suspension control strategy is of fundamental importance to obtain satisfying results. Operational Modal Analysis allows the experimental structural identification in those that are the real operating conditions: Moving from output-only data, leading to modal models linearised around the more interesting working points and, in the case of controlled systems, providing the needed information for the optimal design and verification of the controller performance. All these characters are needed for the experimental assessment of vehicle suspension systems. In the paper two suspension architectures are considered equipping the same car type. The former is a semi-active commercial system, the latter a novel prototypic active system. For the assessment of suspension performance, two different kinds of tests have been considered, proving ground tests on different road profiles and laboratory four poster rig tests. By OMA-processing the signals acquired in the different testing conditions and by comparing the results, it is shown how this tool can be effectively utilised to verify the operation and the performance of those systems, by only carrying out a simple, cost-effective road test.

Design and analysis of suspension system for an All-Terrain vehicle

Enhancing vehicle stability, while maintaining vehicle control and ride comfort, can significantly improve the chances of accident avoidance in an emergency situation. While traditional vehicle suspension systems provide a compromise between ride and handling, this research study proposes the design of a controllable pneumatic suspension system using fluidic muscle pneumatic actuators, providing a low natural frequency response, for improving ride comfort, but having the ability to respond to severe dynamic maneuvers by increasing the suspension stiffness. In addition, individual corner stiffness and damping will be controlled to manage pitch, roll and yaw movement, as well as ride height, in response to road inputs, direction changes, and vehicle load fluctuations. The objective of this research is to develop an active suspension control model that will dynamically optimise both the ride and handling parameters of a pneumatic fluidic muscle suspension on a light, off-road experimental motor vehicle. This paper focusses on phase one of the study, namely the research and design of the active pneumatic suspension system, and also provides test results of fluidic muscle characterisation tests to determine their suitability in this application.