Browse Topic: Passive suspension systems
Potholes are a major cause of discomfort for riders and vehicle damage. The passive suspension systems which are used in the passenger vehicles are primarily reaction based. These can’t adapt to the changing road conditions which means the best ride quality and handling characteristics cannot be ensured for different driving situations. Passive suspension system also needs more maintenance due to its inability to reduce the impact of the road irregularities. In recent years, semi-active suspension systems have been developed to improve ride comfort and vehicle safety. This paper covers the integration of a semi-active suspension system with a road preview mechanism with a TATA car model to investigate its impact on ride comfort, handling characteristics and component loads in digital domain. A quarter car vehicle model is used to compare different active damping control strategies. The best strategy is selected and integrated in a full vehicle MBS model to gain deeper insight on ride
This article proposes an electromagnetic damper (EMD) based on a ball screw mechanical structure actuator. To prove the damping effect of the new damper proposed in this paper. In this paper, the EMD suspension is validated on a quarter vehicle suspension. A mathematical model of quarter vehicle suspension is developed and a sliding mode variable structure controller is designed. This sliding mode controller enables vibration control of the suspension and improves ride comfort. To make the EMD track the ideal current effectively, a variable resistance circuit that can change the electromagnetic damping force is proposed to achieve the graded adjustment of resistance. A semi-active vehicle vibration control strategy was designed, and experiments were conducted using a quarter-vehicle test platform to verify the vibration-damping performance of this EMD suspension. The energy transfer to the road was analyzed and the higher the variable resistance, the more energy is transferred to the
Letter from the Special Issue Editors
In this article, the nonlinear pneumatic magnetorheological (MR) suspension system is designed to improve vehicle characteristics in both ride comfort and dynamic stability. The four-degree-of-freedom (4-DOF) half-vehicle suspension system that is described based on bounce and pitch motions is derived. Both interval type-1 (T-1) and interval type-2 (T-2) of fuzzy models are applied as alternative controllers for the pneumatic MR suspension system. Both a controlled force of air spring and tracking ability of desired damping force are generated for each wheel of alternative controllers. In order to apply voltages for both the front and rear MR dampers, the tracks of desired damping forces are incorporated with the front MR damper controller and rear MR damper controller, respectively. The conventional damping case of the passive suspension system is used as a baseline for comparisons. The control performance criteria are presented in the frequency and time domains to quantify the
The aim of this study is to develop an Add-On Feature that could support the semi-active suspension system controller during longitudinal dynamics maneuvers. The Add-On Feature called Initial Pitch Control (IPC) is activated during launching, shifting, and braking to enhance the pitch motion characteristics and road-holding capability. A sixteen degrees-of-freedom (DoF) vehicle mathematical model represents the vertical and longitudinal dynamics developed and validated via laboratory and road tests. A hydraulic four-poster test rig is used to carry out the laboratory tests for the vertical dynamics verification, while the longitudinal dynamic verification is achieved through the performed tests on a highway track. In order to design the IPC algorithm, the Rule-Optimized (RO) semi-active suspension controller, an Anti-lock Braking System (ABS) controller, and seven gears Dual-Clutch Transmission (DCT) controller are implemented in the vehicle model. An optimization routine has been
The objective of the present article is to design a nonlinear passive suspension system for an automobile subjected to random road excitation which generates a performance as close to a fully active suspension system as possible. Linear Quadratic Regulator (LQR) control is used to synthesize an active suspension system. The control forces corresponding to the nonlinear passive suspension and the active suspension are equated, and the parameters are optimized as the performance error between the two systems is reduced. The nonlinear equations of motion are reduced to equivalent linear equations, where the system states are a function of the vehicle response statistics, by using the equivalent linearization method. The performance of the optimized nonlinear model and the linear model are compared with the performance of the LQR control active suspension system. The nonlinear model performs better than the linear system with chosen parameters. The optimized system achieves almost an equal
The article examines quarter-car dynamics with the possible separation of its tire from the road. A set of nondimensionalized differential equations has been proposed to minimize the involved parameters. Time and frequency response investigation of the system has been analyzed insightfully considering tire-road separation. To measure the separation of the tire, a time fraction index is defined, indicating the fraction of separation time in a cycle at steady-state conditions. Minimizing the index is assumed as the objective of the optimized system. An actuator is applied to the vehicle suspension in parallel with the mainspring and damper of the suspension. Particle Swarm Optimization (PSO) is used to properly tune a Proportional-Integral-Derivative (PID) controller for the active suspension system excited by a harmonic excitation. To verify the effectiveness of the control proposed, the controlled result compared with a passive suspension system illustrates the design, achieving a more
1 Rear wheel drive vehicles have a long driveline using a propeller shaft with two universal joints. Consequently, in this design usage of universal joints within vehicle driveline is inevitable. However, the angularity of the driveshaft resulting from vertical oscillations of the rear axle causes many torsional and bending fluctuations of the driveline. Unfortunately, most of the previously published research work in this area assume the propeller inclination angle is constant under all operating conditions. As a matter of fact, this assumption is not accurate due to the vehicle body attitudes either in pitch or bounce motions. Where the vehicle vibration due to the suspension flexibility, either passive or active type, exists. Moreover, the relative motion between the body and the wheel make this virtualization is so far from the realty in real ground vehicles In this research work, the hydro-pneumatic limited bandwidth active suspension system with wheelbase preview control is
This article presents the suspension performance and the energy harvesting capabilities of a hydraulic regenerative suspension system. A regenerative shock absorber is designed based on a hydraulic transmission mechanism. The proposed regenerative shock absorber is implemented in a quarter-car model to replace the conventional passive damper. The nonlinear damping force of the regenerative shock absorber, which depends on the pressure in the shock absorber chambers, is derived. Using the continuity equation and Kirchhoff’s law, the flow of oil through the valves is described including the oil compressibility. The variation of the check valve opening as a function of pressure difference is also considered in the mathematical modeling. The amount of the harvested power and the efficiency of the regenerative system are introduced to assess the effectiveness of the new suspension system compared to the traditional passive suspension system. Suspension performance indices such as ride
This article presents a semi-active vibration control suspension system using a preview Model Predictive Control (MPC) linked with a magnetorheological (MR) damper to improve vehicle stability during handling dynamics, consequently confidently achieving both maneuverability and lateral dynamic motion. The mathematical model (4DOF) described by bounce and pitch motions for sprung mass and two bounce motions for the un-sprung masses, which consists of a preview half-vehicle suspension system and MR dampers at the front and rear axles, is derived. A nonpreview case of the linear quadratic regulator (LQR), a preview case of the LQR, and a preview case of the MPC as alternative methods are applied to design the system controller in combination with a signum function method as a damper controller for both the front and rear MR dampers. The vehicle handling model based on the look-ahead distance of the road, which includes yaw and lateral motions, is linked with the driver model. Magic
The accuracy of state estimation and optimal control for controllable suspension system is a challenging task for the vehicle suspension system under various road excitations. How to effectively acquire suspension states and choose the reasonable control algorithm become a hot topic in both academia and industry. Uncertainty is unavoidable for the suspension system, e.g., varying sprung or unsprung mass, suspension damping force or spring stiffness. To tackle the above problems, a novel observer-based control approach, which combines adaptive unscented Kalman filter (AUKF) observer and model predictive control (MPC), is proposed in the paper. A quarter semi-active suspension nonlinear model and road profile model are first established. Secondly, using the road classification identification method based on system response, an AUKF algorithm is employed to estimate accurately the state of suspension system. Due to the nonlinear of semi-active suspension damping force in the movement
To achieve the simultaneous improvement in ride comfort of the passenger as well as the stability of the vehicle, a second-order sliding mode controller is proposed in this study. Super twisting algorithm attenuates the chattering effect present in the conventional sliding mode controller without affecting the stability of the system. The Lyapunov stability analysis is carried out to verify the stability of the controller. The effectiveness of the designed super twisting algorithm used second-order sliding mode controller is validated in a semiactive quarter car suspension with seat model. Modified Bouc-wen magnetorheological (MR) damper model is used as a semiactive damper and the voltage that has to be supplied to the magnetorheological damper is controlled by a super twisting algorithm and sliding mode controller. Continuous modulation filtering algorithm is adopted to convert the force signal of a controller into the equivalent voltage input to the MR damper. The entire system is
This paper introduces an optimum design for a feedback controller of a fully active vehicle suspension system using the combined multi-objective particle swarm optimization (CMOPSO) in order to minimize the actuator power consumption while enhancing the ride comfort. The proposed CMOPSO algorithm aims to minimize both the vertical body acceleration and the actuator power consumption by searching about the optimum feedback controller gains. A mathematical model and the equations of motion of the quarter-car active suspension system are considered and simulated using Matlab/Simulink software. The proposed active suspension is compared with both active suspension system controlled using the linear quadratic regulator (LQR) and the passive suspension systems. Suspension performance is evaluated in time and frequency domains to verify the success of the proposed control technique. The simulated results reveal that the proposed controller using CMOPSO grants a significant enhancement of ride
The objective of this paper is to study the influence of a suspension system on the human body with the effect of the controller behavior. For this work, 2-Degree of Freedom (DoF) quarter car suspension system with 4 DoF seated human body is modeled. The mathematical equation is developed by using a lumped mass parameter method. Governing equations of motions are generated by Newton’s Law of motion. Random road profile is also considered for this study. MATLAB/SIMULINK software is used to simulate the system results and system analysis is limited to a Proportional Integral Derivative (PID) controller with hydraulic actuator. Seat to Head transmissibility ratio of the active suspension system is analyzed and compared with the passive suspension system. Finally, to illustrate the effectiveness of the proposed active system, simulated results are compared with ISO 2631 comfort curves. Therefore the result shows that the PID based active suspension system improves the ride comfort of the
A non-linear mathematical model of a semi-active (2DOF) vehicle suspension using a magnetorheological (MR) damper with information concerning the road profile ahead of the vehicle is proposed in this paper. The semi-active vibration control system using an MR damper consists of two nested controllers: a system controller and a damper controller. The fuzzy logic technique is used to design the system controller based on both the dynamic responses of the suspension and the Padé approximation algorithm method of a preview control to evaluate the desired damping force. In addition, look-ahead preview of the excitations resulting from road irregularities is used to quickly mitigate the effect of the control system time delay on the damper response. Adaptive neuro-fuzzy inference system (ANFIS) inverse model without preview, ANFIS inverse model with preview, and ANFIS inverse model with preview and optimization strategies are used to design the damper controller to evaluate different values
The design of passive suspension systems is being improved since the early days of the automotive industry in order to obtain the best tradeoff between ride comfort and handling. In this context, passenger cars tend to prioritise ride comfort whilst racing cars tend to focus on handling. On the other hand, Formula SAE is a series of undergraduate competitions in which the students design, build and compete with small, formula-style, mono-seated vehicles. As part of the competition events, the vehicle experiences tight corners and short-length slaloms. The minimum turning diameter and the shortest length of slalom period conducted by Formula SAE prototypes are 9 m and 7.6 m, respectively. Therefore, high controllability of vehicle dynamic behaviour is required in order to enhance the cornering speed, this is achievable by working on the dampers to optimise the rates of load transfer in cornering. This paper describes the development of semiactive control algorithms to optimise the
Proportional integral derivative (PID) control method is an effective, easy in implementation and famous control technique applied in several engineering systems. Also, Genetic Algorithm (GA) is a suitable approach for optimum searching problems in science, industrial and engineering applications. This paper presents the usage of GA for determining the optimal PID controller gains and their implementation in the active quarter-vehicle suspension system to achieve good ride comfort and vehicle stability levels. The GA is applied to solve a combined multi-objective (CMO) problem to tune PID controller gains of vehicle active suspension system for the first time. The active vehicle suspension system is modeled mathematically as a two degree-of-freedom mechanical system and simulated using Matlab/Simulink software. The performance of the proposed suspension system controlled using the optimized PID GA is compared to both controlled system using the classical PID (C PID) controller and the
Proportional integral derivative (PID) control technique is the most common control algorithm applied in various engineering applications. Also, particle swarm optimization (PSO) is extensively applied in various optimization problems. This paper introduces an investigation into the use of a PSO algorithm to tune the PID controller for a semi-active vehicle suspension system incorporating magnetorheological (MR) damper to improve the ride comfort and vehicle stability. The proposed suspension system consists of a system controller that determine the desired damping force using a PID controller tuned using PSO, and a continuous state damper controller that estimate the command voltage that is required to track the desired damping force. The PSO technique is applied to solve the nonlinear optimization problem to find the PID controller gains by identifying the optimal problem solution through cooperation and competition among the individuals of a swarm. A mathematical model of a two
Idealized mathematical models, also known as lumped parameter models (LPMs), are widely used in analyzing vehicles for ride comfort and driving attributes. However, the limitations of some of these LPMs are sometimes not apparent and a rigorous comparative study of common LPMs is necessary in ascertaining their suitability for various dynamic situations. In the present study, the mathematical descriptions of three common LPMs, viz. quarter, half and full car models, are systematically presented and solved for the appropriate response parameters such as body acceleration, body displacement, and, pitch and roll angles using representative passive suspension system properties. By carrying out a comparison of the three stated LPMs for hump-type road profiles, important quantitative insights, not previously reported in the literature, are generated into their behaviors so that their applications can be judicious and efficient
This paper presents a new and effective control concept for semi-active suspension systems. The proposed controller uses a Fuzzy Logic scheme which offers new opportunities in the improvement of vehicle ride performance. The Fuzzy Logic scheme tunes the controller to treat the conflict requirements of ride comfort and road holding parameters within a specified range of the suspension deflection. An eleven degree of freedom full vehicle ride dynamics model is constructed and validated through laboratory tests performed on a hydraulic four-poster shaker. A new optimization process for obtaining the optimum Fuzzy Logic membership functions and the optimum rule-base of the proposed semi-active suspension controller is proposed. Discrete optimization has been performed with a Genetic Algorithm (GA) to find the global optima of the cost function which considers the ride comfort and road holding performance of the full vehicle. The proposed Fuzzy Logic semi-active controller is compared to
The paper deals with a theoretical study to present a new sort of the buses suspension systems employs a hydraulic connection between the front and rear dampers together with active suspension actuator at the front axle. The theoretical investigation based on a half vehicle model of the bus suspension system includes the engine mounting system. The hydraulic connection between the front and rear dampers is created according to the capillary tubes theory. Furthermore, the active suspension system control algorithm based on the optimal control theory is derived. The Genetic Algorithm optimization routine is applied to generate the active suspension control algorithm parameters. A comparison between the connected dampers suspension system, active suspension system, active-connected dampers suspension system, and the passive suspension system in terms of ride comfort and road holding at constant suspension working space is performed. The results showed that, the proposed active-connected
Semi-active suspension systems for ground vehicles have been the focus of research for several years as they offer improvements in vehicle comfort and handling. This kind of suspension has attracted more interest compared to active suspension systems especially due to lower cost and energy consumption. In this paper the capabilities of a semi-active front axle suspension are investigated for a commercial vehicle. A half-truck model of a 4x2 tractor and semitrailer combination is developed in Matlab/Simulink for this purpose. Also, a 2 DOF roll plane model is considered to capture the roll motion of the vehicle body mass. Employing the above-mentioned models, results from on-off and continuous variable semi-active damping systems are compared to the ones from the passive suspension system according to ride comfort and handling safety characteristics. Simulations are performed in the time domain with realistic road-induced excitations, namely random road and single/double-sided bump
This paper discusses research conducted by the U.S. Army Research Laboratory (ARL) - Vehicle Technology Directorate (VTD) on advanced suspension control. ARL-VTD has conducted research on advanced suspension systems that will reduce the chassis vibration of ground vehicles while maintaining tire contact with the road surface. The purpose of this research is to reduce vibration-induced fatigue to the Warfighter as well as to improve the target aiming precision in-theater. The objective of this paper was to explore the performance effectiveness of various formulations of the Generalized Predictive Control (GPC) algorithm in a simulation environment. Each version of the control algorithm was applied to an identical model subjected to the same ground disturbance input and compared to a baseline passive suspension system. The control algorithms considered include a GPC with Implicit Disturbances, GPC with Explicit Disturbances, and GPC with Preview Control. A two-axle tactical vehicle with
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