Conventional Passive Suspension Research Articles

Adaptive robust constraint-following control method for improving carbody hunting stability of high-speed trains

The low-frequency carbody hunting motion of high-speed trains (HSTs) frequently occurs due to the complex operating environment and deterioration of wheel–rail contact conditions. It not only affects ride comfort but also poses a risk of derailment safety accidents for HSTs. In such scenarios, traditional passive suspension systems struggle to ensure satisfactory dynamic performance of HSTs. However, active suspension systems can offer an effective solution. To enhance the low-frequency carbody hunting stability and environmental adaptability of HSTs, this study proposes a novel adaptive robust displacement inequality constraint following control (AICFC) method for active suspension utilising the beneficial nonlinearity inspired by bio-inspired structures (BIS). The effectiveness of the proposed AICFC-BIS method is validated through numerical simulations comparing it with other control strategies. Simulation results show that the AICFC-BIS method can effectively suppress low-frequency carbody hunting motion and improve the dynamic performance of HSTs. Compared with conventional passive suspensions and other active suspensions, HSTs equipped with AICFC-BIS active suspension exhibit significantly reduced operational safety risk and improved ride comfort indices while being energy efficient.

Integrating of LMIs with Buckingham Π theorem for control of uncertain oscillating systems

This paper introduces a novel framework for robust controller synthesis in oscillating systems by synergistically combining generalized linear matrix inequalities (GLMIs) with the Buckingham Π theorem. The primary goal is to enhance the design of robust controllers for systems with uncertain parameters through the exploitation of dimensionless groups derived from the Buckingham Π theorem. By establishing a dimensionless state-space representation, the proposed approach demonstrates adaptability to a broad spectrum of similar systems. The LMI-based formulation facilitates the systematic design of controllers capable of effectively mitigating the impact of parametric uncertainties. Simulation results for an uncertain inverted pendulum and a vehicle active suspension system validate the superior performance of the proposed method compared to conventional control techniques, such as MPC, LQG, SMC, PID, and LQR. For the uncertain inverted pendulum system, the proposed robust control scheme achieves a cart position stabilization in 5.35 s and pendulum stabilization in 6.3 s, which is faster than standard control algorithms. In the context of the vehicle active suspension system, the performance indices for sprung mass acceleration, suspension deflection, and tire deflection are 0.19, 0.47, and 0.07, respectively. These values indicate significant reductions when compared to conventional passive suspension systems and standard robust control methodologies.

Vibration damping by enhancing of magneto-rheological damper performance using novel smart fluid

The objective of the present work is to improve the speed and vibration characteristics of tracked vehicles via a semi-active suspension system that uses a Magneto-Rheological (MR) damper. MR damper is designed, manufactured, and tested with different harmonic excitations. The MR damper reliability under high-frequency stresses is considered in the mechanical design phase as well as the configurations and dimensions of the damper. Two fluid samples DELTA and GAMA are prepared, which differ in carrier fluid dynamic viscosities to have different rheological properties and tested to determine the dynamic characteristics of the damper. The damper’s ability to isolate vibration is measured by MTS. The investigation performed not only clarifies MR fluid characteristics but also proves the fact that the fluid is non-Newtonian with good rheological properties. One of the two fluid samples called DELTA is found to have the required properties. The MR damper filled with this DELTA shows a significant increase in damping force according to the excitation current and is much higher than the conventional passive suspension damping force. The proposed damper can cope with the increase in both magnitude and frequency of the input, which represents the speed of the truck and roughness of the road. Upgrading the suspension system of the vehicle from a passive damper to a manufactured semi-active MR damper with MR fluid DELTA can increase the damping force that the passive damper produces by 207% in compression stroke and 136.2% in rebound stroke at the same testing conditions.

Design a new algorithm (iL-GA) to optimize controller parameters for an automotive suspension system

Purpose This paper aims to design a PD controller for an active suspension system to improve the car’s moving smoothness. Design/methodology/approach The controller parameters are optimized by an in-loop genetic algorithm (iL-GA). Unlike previous studies that only used conventional GAs to tune coefficients for the controller, the iL-GA designed in this paper provides outstanding efficiency when determining the optimal value range for the system. The optimal value range of parameters is determined by the in-loop algorithm based on criteria related to systematic errors. The optimal values are then calculated by the GA based on this range instead of an uncertain one. Findings Simulation results show that vehicle body acceleration and displacement values are significantly reduced when using the active suspension system compared to the conventional passive suspension system. The phase difference phenomenon does not occur in the iL-GA situation. In addition, the frequency domain investigation also shows the system’s stability when using iL-GA instead of conventional GA. Originality/value To the best of the authors’ knowledge, this is a new application that provides positive effects to the suspension controller. This algorithm can be applied to tune coefficients for direct controllers in the future.

Dynamic behavior of three-wheel vehicle with inerter-based dynamic absorber suspension system

Three-wheeled vehicles may be a better choice as compared with four-wheeler cars provided they are properly designed to improve the rollover stabilities and ride comfort. The design modifications need improvement in geometry and suspension. This article presents the dynamic behavior of three-wheeled vehicle equipped with an inerter-based dynamic absorber and compares the same with the conventional suspension system. The performance parameters analyzed are vertical-lateral acceleration, front & rear suspension deflection, and front & rear dynamic tyre loads. The analytical rigid body model is formulated by assigning 9 degrees of freedom to the system for the evaluation of performance parameters to compare the inerter-based absorber suspension with the conventional passive suspension system.

A new energy-feeding variable damping control strategy for electromagnetic hybrid suspension systems

Traditional energy-feeding suspensions exhibit a non-adjustable damping characteristic during energy recovery, which can compromise the dynamic performance of the suspension system. To overcome this issue, this paper proposes an energy-feeding variable damping control strategy (EFVD) predicated on an electromagnetic hybrid suspension system. This strategy aims to achieve adjustable damping during energy recovery, reducing energy losses while ensuring optimal suspension performance. Building on a half-vehicle suspension model, we construct a dynamic model of the electromagnetic hybrid suspension. By leveraging an enhanced hybrid-skyhook and ground-hook control algorithm (HSGH), we solve for the target control force. We then design a force distribution controller based on the EFVD strategy, aiming to optimize suspension dynamic performance and energy feeding efficiency. And we conduct a simulation study, measuring power supply efficiency and suspension dynamic performance as key evaluation metrics. The results demonstrate the superiority of the proposed EFVD strategy over conventional passive and active suspension control strategies, highlighting its effectiveness and reliability in maintaining dynamic performance while enhancing energy efficiency. This underscores the potential of the EFVD strategy as a practical solution for future suspension system design and energy management.

Research on the Multimode Switching Control of Intelligent Suspension Based on Binocular Distance Recognition

As the upgrade of people’s requirements for automotive driving comfort, conventional passive suspensions for cars have fallen short of existing demands due to their nonadjustable damping and stiffness, so semiactive suspensions and active suspensions have gained growing acceptance. Compared with active suspensions, semiactive suspensions offer the advantages of a low manufacturing cost and reliable structure, and thus have become the preferred choice for most vehicles. To optimize the control effect of semiactive suspensions under different working conditions, this paper completed the modeling of magnetorheological semiactive suspension system dynamics and road inputs; then, the design of binocular camera sensing algorithms was performed to obtain the real-time distance of the target using the point cloud ranging function, and the parameters required for suspension control were also obtained. This was followed by the completion of the control-mode-switching rules and the design of the suspension controller. According to the different control objectives, the mode could be divided into the obstacle-road mode, straight-road mode, and curved-road mode. The suspension controller included the BP-PID (neural network PID controller) controller and the force distributor. Finally, the effectiveness of the mode-switching rules and the control method was verified through system simulation and the hardware-in-the-loop test.

Fuzzy logic control of active suspension system equipped with a hydraulic actuator

In this paper, the Active Suspension System (ASS) of road vehicles was investigated. In addition to the conventional stiffness and damper, the proposed ASS includes a fuzzy controller, a hydraulic actuator, and an LVDT position sensor. Furthermore, this paper presents a nonlinear model describing the operation of the hydraulic actuator as a part of the suspension system. Additionally, the detailed steps of the fuzzy controller design for such a system are introduced. A MATLAB/Simulink model was constructed to study the proposed ASS at different profiles of road irregularities. The results have shown that the proposed ASS has superior performance compared to the conventional Passive Suspension System (PSS), where the body displacement can be minimized to about 70.1 % and the settling time is reduced to about 48.4 %. Also, the results have shown that the actuator force can reach 68 % of the body weight under the worst studied road conditions.

Analysis of ride comfort and road friendliness of heavy vehicle inertial suspension based on the ground-hook control strategy

In order to comprehensively improve the ride comfort performance and the road friendliness performance of the heavy vehicles, an inertial suspension using ground-hook (GH) control is proposed in this paper, and the suspension performances are compared at different loading rates and driving speeds. Firstly, a half vehicle model of the inertial suspension of the heavy vehicle based on the GH control is established. Then, the key parameters of the GH inertial suspension are optimized by the genetic algorithm and the system simulations are carried out. By comparing to the conventional passive suspension, the root-mean-square (RMS) of the vertical acceleration of the body centroid is reduced by 4.87%, and the RMS of the dynamic tire loads of the front and the rear wheels are reduced by 16.19% and 10.02%, respectively. Results show that the GH inertial suspension can effectively coordinate and improve the ride comfort and road friendliness of heavy vehicles simultaneously.

Mu-Synthesis PID Control of Full-Car With Parallel Active Link Suspension Under Variable Payload

This article presents a combined <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> -synthesis PID control scheme, employing a frequency separation paradigm, for a recently proposed novel active suspension, the Parallel Active Link Suspension (PALS). The developed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> -synthesis control scheme is superior to the conventional <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$H_{\infty }$</tex-math></inline-formula> control, previously designed for the PALS, in terms of ride comfort and road holding (higher frequency dynamics), with important realistic uncertainties, such as in vehicle payload, taken into account. The developed PID control method is applied to guarantee good chassis attitude control capabilities and minimization of pitch and roll motions (low frequency dynamics). A multi-objective control method, which merges the aforementioned PID and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> -synthesis-based controls is further introduced to achieve simultaneously the low frequency mitigation of attitude motions and the high frequency vibration suppression of the vehicle. A seven-degree-of-freedom Sport Utility Vehicle (SUV) full car model with PALS, is employed in this work to test the synthesized controller by nonlinear simulations with different ISO-defined road events and variable vehicle payload. The results demonstrate the control scheme's significant robustness and performance, as compared to the conventional passive suspension as well as the actively controlled PALS by conventional <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$H_{\infty }$</tex-math></inline-formula> control, achieved for a wide range of vehicle payload considered in the investigation.

Improving rail vehicle dynamic performance with active suspension

Today, it is difficult to further improve the dynamic performance of rail vehicles with conventional passive suspension. Also, simplified vehicle respectively running gear layouts that significantly could reduce vehicle weights are difficult to realize with modern requirements on passenger vibration comfort and wheel and rail wear. Active suspension is a powerful technology that can improve the vehicle dynamic performance and make simplified vehicle concepts possible. The KTH Railway group has, together with external partners, investigated active suspensions both numerically and experimentally for 15 years. The paper provides a summary of the activities and the most important findings. One major project carried out in close collaboration with the vehicle manufacturer Bombardier and the Swedish Transport Administration was the Green Train project, where a 2-car EMU test bench was used to demonstrate different active technologies. In ongoing projects, a concept of single axle - single suspension running gear is developed with active suspension both for comfort improvement and reduced wheel wear in curves. The results from on-track tests in the Green Train project were so good that the technology is now implemented in commercial trains and the simulation results for the single-axle running gear are very promising.

Parallel Active Link Suspension: Full Car Application With Frequency-Dependent Multiobjective Control Strategies

In this article, a recently proposed at basic level novel suspension for road vehicles, the parallel active link suspension (PALS), is investigated in the realistic scenario of a sport utility vehicle (SUV) full car. The involved rocker-pushrod assembly is generally optimized to maximize the PALS capability in improving the suspension performance. To fully release the PALS functions of dealing with both low- and high-frequency road cases, a PID control scheme is first employed for the chassis attitude stabilization, focusing on the minimization of both the roll and pitch angles; based on a derived linear equivalent model of the PALS-retrofitted full car, an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$H_{\infty }$ </tex-math></inline-formula> control scheme is designed to enhance the ride comfort and road holding; moreover, a frequency-dependent multiobjective control strategy that combines the developed PID and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$H_{\infty }$ </tex-math></inline-formula> control is proposed to enable: 1) chassis attitude stabilization at 0–1 Hz; 2) vehicle vibration attenuation at 1–8 Hz; and 3) control effort penalization (for energy saving) above 10 Hz. With a group of ISO-defined road events tested, numerical simulation results demonstrate that, compared to the conventional passive suspension, the PALS has a promising potential in full-car application, with up to 70% reduction of the chassis vertical acceleration in speed bumps and chassis leveling capability of dealing with up to 4.3-m/s <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> lateral acceleration.

Study of Performance of Incorporating Pneumatic Suspension System with the Hydraulic Actuator for Quarter Car and Using Controllers with Genetic Algorithm

Suspension systems are one of the main parts of the vehicle that provide the passenger comfort and stability, while it is difficult for conventional passive suspension systems to cope with the vibrations to which the vehicle is exposed. Air suspension systems have a dynamic character that allows good handling of the road and a comfortable ride, but in a certain area for this reason the stiffness of the air suspension must be flexibly changed. The air suspension has been developed with the inclusion of a hydraulic actuator to create an additional force that withstands the incoming vibration from the road. The pneumatic suspension system parameters, such as vertical acceleration, road holding, and vertical displacement, are improved continuously based on the controllers that have been used for nonlinear pneumatic suspension systems, fractional order proportional integral derivative (FOPID), and fuzzy logic control (FLC). The genetic algorithm is utilized to tune the controller's parameters to the nonlinear active pneumatic system's 3-DOF. A model's simulation outcomes with controllers improved the suspension performance. The proposed active pneumatic system and pneumatic suspension systems are compared when a vehicle is traveling at a speed of 72 km/h on an ISO level B road to test the ability and efficiency of the system to suppress body vibration to enhance safety and provide a comfortable ride on rough roads. According to simulation results, the improved suspension substantially lowers vertical vibrations and enhances road adaptability.

A Hybrid Control Algorithm Fuzzy-PI with the Second Derivative of the Error Signal for an Active Suspension System

A vehicle’s oscillation can be improved by using an active suspension system to replace the conventional passive suspension system. The active suspension system operates on the control signal from the controller. This paper introduces the Fuzzy-PI integrated control algorithm to control the system’s efficiency. The Fuzzy algorithm adjusts the KP and KI parameters of the controller. This response depends on the oscillation state of the vehicle. A quarter model with a hydraulic actuator was used in this research. The simulation process takes place in the MATLAB-Simulink environment. In the first case, the maximum and average values of displacement and acceleration of the sprung mass when the vehicle uses the Fuzzy-PI algorithm are only 2.68%, 1.34%, and 1.65%, 0.66%, respectively, compared to the situation of vehicles using the passive suspension system. For the second case, these values are 3.33%, 1.69%, and 2.01%, 0.73%, respectively. As a result, the vehicle’s stability and comfort are greatly enhanced when the integrated controller is used. Besides, the change of KP and KI parameters is also completely suitable for the vehicle’s driving conditions. This research only leads to calculations and simulations; the experimental process is expected to occur soon.

Research on adaptive speed control method of an autonomous vehicle passing a speed bump on the highway based on a genetic algorithm

Abstract. When autonomous vehicles pass through uneven roads, especially the consecutive speed control humps (SCHs) on expressways, the speed of them will have a significant influence on the safety and comfort of driving. How to automatically select the most appropriate speed has become a practical research subject. This paper studies the nonlinear vibration process of the suspension system when the autonomous vehicle passes through the SCHs on a highway. Firstly, the paper establishes a four-degree-of-freedom (4-DOF) nonlinear half-vehicle model and a stimulation function of trapezoidal SCHs and then uses the Runge–Kutta method to numerically solve the differential equations of motion of the suspension system. In the next part, the paper chooses the genetic algorithm to build a multi-objective optimization problem model, which selects the vertical displacement of the vehicle body, the suspension's dynamic deflection and the dynamic load of the tire as optimization objectives and combines the method of the unified objective function to find the optimal passing speed. Finally, the paper designs and carries out the solution process of the multi-objective optimization problem for the vehicle under three scenarios, conventional passive suspension, semi-active suspension, active suspension, and compares the optimized state with the pre-optimized state to prove the effectiveness of the optimization model.

LQR Control with the New Triple In-Loops Algorithm for Optimization of the Tuning Parameters

The suspension system plays a role in ensuring the stability of the vehicle when traveling on the road. On many modern vehicles, the active suspension system has been proposed to replace the conventional passive suspension system. The performance of the controller for the active suspension system depends on its control method. In this paper, a half dynamics model of the vehicle is established. Besides, the LQR control method is also used. The parameters of the control matrix are calculated through the triple in-loop optimization algorithm, which has been shown in the research. This is a completely novel algorithm. This algorithm helps to choose the most optimal parameters. Thus, it ensures the efficiency and stability of the controller. The calculation and comparison process are done automatically. When the loop ends, the optimal parameters are explicitly indicated. The simulation process is done in the MATLAB-Simulink environment. The results of the research showed that when the LQR controller, which was optimized through the triple in-loop algorithm used, the vehicle's oscillation was significantly reduced. In the three survey situations, the values of the roll angle and the angular acceleration of the sprung mass are guaranteed to be stable. Besides, when using this controller, the phenomenon of “chattering” after the excitation ends does not appear. This topic can be further developed in the future.

A reinforcement learning backstepping‐based control design for a full vehicle active Macpherson suspension system

This paper presents a reinforcement learning backstepping-based control scheme for the design of a full vehicle active suspension system such that both the superior ride comfort and stabilization are achieved. It is well known that the traditional backstepping control scheme is suitable to solve higher order nonlinear system based on the strict-feedback form; however, the disadvantage of the procedure requires computing the derivatives of virtual control signals, which is a very complex task. Therefore, a reinforcement learning scheme using the deep deterministic policy gradient (DDPG) control strategy is developed to replace the process of finding virtual control force in backstepping method. It not only avoids the complexity of analytically calculating the derivatives of the virtual control signals, but also retains the systems robustness when there exist random disturbances from road irregularities. To verify the performance of the proposed active suspension control scheme, the random road unevenness profiles according to ISO 8608 is considered as vertical and lateral disturbance input excitation of a full-vehicle suspension system. Compared with conventional passive suspension system and backstepping control scheme, the proposed approach can be demonstrated to not only effectively improve ride comfort under random road excitation, but also improve the transient response and robustness.

Design of Active Tyre-Suspension-Seat System Through Multibody Model and Genetic Algorithms

The tyre-suspension-seat dynamic system, driveline and engine vibrations are generally considered in the vibrational field as the main factors that influence the particular feeling of comfort perceived by passengers on a vehicle. Hence, the development of several criteria and models for the optimal estimation of the design parameters of such systems. Among these parameters, the most detrimental impacting on the passenger comfort are undoubtedly acceleration and its variation. The two types of suspension systems (conventional passive suspension system and active suspension system) differ as the first foresees the spring-damper characteristics to be adjusted so that only one of several conflicting objectives (such as passenger comfort, road holding, and suspension deflection) is followed. In active suspension systems, instead, these objectives are balanced by the designer in a more efficient manner thanks to the feedback-controller actuator assembly. However, this approach presents some limitations linked to the extremely wide spectrum of magnitude and frequency of external forces that the tyre-suspension-seat system has to efficiently control and mitigate. It remains that in the existing optimisation models and systems time exposure limits established by unification agencies and road authorities are not generally considered. This paper illustrates the development of an active tyre-suspension-seat system control for passenger cars, using both a non-linear multibody model and Genetic Algorithm (GA) controls. A benefit of the proposed active tyre-suspension-seat system control is also to consider various time exposure limits and an active damping element. The main innovative element introduced by this work consists in having coupled an active control to passive mechanical parameters in order to minimize the seat acceleration. The 3 DoF multibody model, applied to a quarter body for symmetry reasons, treated road roughness as an input variable in the GA control so as to determine the vertical component of acceleration. The numerical and experimental applications of the proposed model to a specific case study allowed to validate the effectiveness of the active system towards the vibrations transmitted to the passenger.

Vibration Isolation of Railway Vehicle Car body using Semi-active Suspension

In the past, the magnetorheological (MR) suspension for railway vehicle has obtained great attention for the isolation of vibrations. This work presents a numerical approach to analyse skyhook and ground hook semi-active control methods for railway vehicle suspension. A 10 DoF model of the railway vehicle system is formulated for the comparative analysis between conventional passive and semi-active suspension control in the present study. The non-linear analysis is investigated in time and frequency domain for the sinusoidal excitations from the track.

Improving the Comfort of the Vehicle Based on Using the Active Suspension System Controlled by the Double-Integrated Controller

When the vehicle moves on the road, many external factors affect the vehicle. These effects can cause oscillation and instability for the vehicle. The oscillation of the vehicle directly affects the safety and comfort of passengers. The suspension system is used to control and extinguish these oscillations. However, the conventional passive suspension system is unable to fully meet the vehicle’s requirements for stability and comfort. To improve these problems, these are much modern suspension system models that have been used in the vehicle to replace the passive suspension system. The modern suspension systems are used as the air suspension system, semiactive suspension system, and active suspension system. These systems which are controlled automatically by the controller were established based on the control methods. There are a lot of control methods which are used to control the operation of the active suspension system. These methods have their advantages and disadvantages. Almost, conventional control methods such as PID, LQR, or SMC are commonly used. However, they do not provide optimal efficiency in improving a vehicle’s oscillation. Therefore, it is necessary to establish a novel solution for the active suspension system control to improve the vehicle’s oscillation. In this paper, the method of using the double-integrated controller is proposed to solve the above problem. The double-integrated controller consists of two hydraulic actuators which are controlled completely separately. This is a completely novel and original method that can provide positive effects. This research focuses on establishing, simulating, and evaluating the novel control method (the double-integrated control) for the active suspension system. The results of the research have shown that when the vehicle is equipped with the active suspension system which is controlled by the double-integrated controller, the maximum values of displacement and acceleration of the sprung mass are significantly reduced. They reach only 6.25% and 9.10% (case 1) and 6.00% and 6.12% (case 2) compared to the conventional passive suspension system. Besides, its average values which are calculated by RMS are only about 3.91% and 4.67% (case 1) and 4.48% and 4.77% (case 2) compared to the above case. Therefore, the comfort and stability of the vehicle have been improved. This paper provides new concepts and knowledge about the double-integrated control method which will become the trend to be used in the next time for the systems of the vehicle. In the future, experimental procedures also need to be conducted to be able to more accurately evaluate the results of this research.