Vehicle Suspension Research Articles

Effectiveness of a Series of Road Humps on Home Zone Streets: A Case Study

Traffic calming measures are implemented more and more often in residential districts as part of home zone sustainability projects. For economic reasons, road humps are the most commonly used traffic calming measures to slow down the traffic within the home zone. Prefabricated units or concrete pavers are the materials of choice for their construction. The studies carried out so far on many different road hump types covered the effect of height, approach/departure ramp inclination(s), and intervals between successive humps on the final speed and the safety of road traffic. The impacts of braking before and acceleration after passing a hump on the pavement and the effect of the associated shocks on the riding comfort of both drivers and passengers and vehicle suspension were also investigated. What is missing in the available literature is information on the slowing effect of road humps depending on the longitudinal gradient of the street and the street’s landscaping. This article is intended to fill this gap by presenting the results of speed surveys carried out on three selected two-way streets located in home zones with different longitudinal gradients and a few humps of different designs that are placed at different intervals. Speeds were measured both before and after each of the successive humps. The “after” speeds were found to depend not only on the hump type and parameters but also on the direction of travel, vertical alignment of the street, parking location, and orientation of the parking space relative to the road axis.

On Adaptive Fractional Dynamic Sliding Mode Control of Suspension System

This paper introduces a novel adaptive control method for suspension vehicle systems in response to road disturbances. The considered model is based on an active symmetry quarter car (SQC) fractional order suspension system (FOSS). The word symmetry in SQC refers to the symmetry of the suspension system in the front tires or the rear tires of the car. The active suspension controller is generally driven by an external force like a hydraulic or pneumatic actuator. The external force of the actuator is determined using fractional dynamic sliding mode control (FDSMC) to counteract road disturbances and eliminate the chattering caused by sliding mode control (SMC). In FDSMC, a fractional integral acts as a low-pass filter before the system actuator to remove high-frequency chattering, necessitating an additional state for FDSMC implementation assuming all FOSS state variables are available but the parameters are unknown and uncertain. Hence, an adaptive procedure is proposed to estimate these parameters. To enhance closed-loop system performance, an adaptive proportional-integral (PI) procedure is also employed, resulting in the FDSMC-PI approach. A comparison is made between two SQC suspension system models, the fractional order suspension system (FOSS) and the integer order suspension system (IOSS). The IOSS controller is based on dynamic sliding mode control (DSMC) and a PI procedure (DSMC-PI). The results show that FDSMC outperforms DSMC.

Modeling and Optimization of Regenerative MacPherson Strut

<div>Throughout the vehicles industry and electrification, vehicle ride comfort, road holding, and fuel/charge economy have always been important considerations for the design and development of shock absorbers. Vehicle suspension is one of the oscillating power dissipation sources in which the undesired mechanical energy is dissipated into heat waste. Therefore, in this study a regenerative MacPherson strut is modeled and validated to investigate the vehicle vertical dynamics performance as well as the harvestable power that can be used to charge batteries or power vehicle electrical loads. The optimal design parameters of the regenerative MacPherson strut (RE.M.S) is obtained by using multi-object genetic algorithm (MOGA) optimization for a better trade-off between regenerated power, ride comfort, and road holding. The results showed that RE.M.S can function as a semi-active shock absorber as change of duty cycle of charging circuit. Furthermore, the optimal selection of the design parameters such as the inclination angle of the MacPherson strut and the external load have a very significant effect to stabilize the level of the harvested regenerated power, ride comfort, and road holding at different driving conditions.</div>

Comparison of Control Methods for Half-Car Active Suspension System

Suspension systems are of great importance in ensuring stable driving in vehicles and the appropriate reaction of vehicle sub-elements against disturbing inputs. Active suspension systems react quickly to road and driving conditions and positively affect vehicle dynamics and passenger comfort. The main factor in improving active suspension systems' performance is determining the suitable control method against the determined disturbing inputs. This study aims to contribute to the development of vehicle suspension technology by investigating the potential of optimizing the performance of active suspension systems with different control algorithms. In the study, a half-car model with an active suspension system was simulated on three different road profiles: bump-pit, sinusoidal, and ISO-8608. Fuzzy logic, PID, Fuzzy-PID, and MPC control methods are used to control the active suspension system, and their advantages over each other and the passive suspension system are investigated. The effectiveness of the control methods determined on each road profile has been analyzed in the evaluations made regarding vehicle dynamics and passenger comfort. As a result of the study, it is observed that the MPC control algorithm was able to control the active suspension system stably and quickly on all three road profiles with a high success rate. The best results are obtained by the MPC algorithm for bump pit, sinusoidal, and ISO8608 road profiles, and the RMSE values for each road profile are 1.466, 0.047, and 0.449, respectively. The suitable control method minimized vehicle body displacement and pitch angle and improved vehicle stability. In the passenger comfort evaluation, 33.49%, 47.79%, and 12.26% improvements were obtained using the MPC control method on bump-pit, sinusoidal, and ISO-8608 road profiles, respectively.

New Mixed Skyhook and Displacement–Velocity Control for Improving the Effectiveness of Vibration Isolation in the Lateral Suspension System of a Railway Vehicle

Demands for increasing the velocity and load carrying capacity of railway vehicles are a challenge to the passive suspension systems used for isolating the lateral vibrations of the carbody of a railway vehicle, especially under a wide range of vibration frequencies. Semiactive suspension systems, especially systems with a magnetorheological damper (MRD), have been investigated as promising alternatives. Many control algorithms have been developed for fine-tuning the damping force generated by MRDs, but they have been ineffective in isolating carbody vibrations at or around the resonance frequencies of the carbody and bogie. This study aims to develop a mixed control algorithm for a new skyhook (SH) control and a new displacement–velocity (DV) control to improve the effectiveness of vibration isolation in resonance frequency regions while producing high performance across the remaining frequencies. The damping coefficient of the new SH controller depends on the vibration velocity of the components of the suspension system and the skyhook damping variable, whereas that of the new DV controller depends on the velocity and displacement of the components of the suspension system and the stiffness variable. The values of the skyhook damping variable and stiffness variable were identified from the vibration velocity of the carbody using the trial and error method. The results of a numerical simulation problem indicated that the proposed control method worked effectively at low frequencies, similar to the conventional SH–DV controller, whereas it significantly improved ride comfort at high frequencies; at the resonance frequency of the bogie (14.6 Hz), in particular, it reduced the vibration velocity and acceleration of the carbody by 50.85% and 45.39%, respectively, compared with the conventional mixed SH–DV controller. The simplicity and high performance of the new mixed SH–DV control algorithm makes it a promising tool to be applied to the semiactive suspension of railway vehicles in real-world applications.

Dynamic characteristics of a semi-active fractional-order inerter-based suspension with acceleration-velocity switch control

The fractional-order differential theory is applied in the hydraulic inerter to describe its mechanical characteristic, a semi-active fractional-order (SA-FO) inerter based on the hydraulic inerter is proposed and used in the vehicle suspension to constitute the semi-active fractional-order inerter-based (SA-FOIB) suspension, which consists of two adjustable inertances. According to the mechanical characteristic of the inerter, the acceleration-velocity switch (AVS) control strategy is proposed to adjust the inertance of the SA-FO inerter. The dynamic model of the SA-FOIB suspension with AVS control is established, its dynamic response under road harmonic excitation is obtained using the averaging method, the dynamic performance under road harmonic and random excitations is analyzed and evaluated by the vehicle body acceleration, suspension dynamic deflection and wheel dynamic load, the optimized structural parameters are obtained using the genetic algorithm optimization method. The results show that for road harmonic excitation, the SA-FOIB suspension can further enhance the high-frequency dynamic performance of the passive fractional-order inerter-based (P-FOIB) suspension, which the high-frequency resonance peaks of the dynamic performance indices are smaller. For road random excitation, the SA-FOIB suspension can decrease the root-mean-square (RMS) values of the suspension dynamic deflection and wheel dynamic load compared with the P-FOIB suspension, while increases the RMS value of the vehicle body acceleration. The optimized SA-FOIB suspension further improves the dynamic performance of the suspension dynamic deflection and wheel dynamic load, which the corresponding RMS values are smaller than the unoptimized SA-FOIB suspension, while deteriorates the vehicle body acceleration.

5-Aminosalicylic Acid Distribution into the Intestinal Membrane Along the Gastrointestinal Tract After Oral Administration in Rats.

5-Aminosalicylic acid (5-ASA), the first-line therapy for ulcerative colitis, is a poorly soluble zwitterionic drug. Unformulated 5-ASA is thought to be extensively absorbed in the small intestine. The pH-dependent solubility of 5-ASA in vitro and the intestinal membrane distribution of 5-ASA and its N-acetyl metabolite (AC-5-ASA) after the oral administration of 5-ASA were examined in fed rats. 5-ASA was administered as a suspension in water, 0.1 M HCl, or 0.1 M NaOH to untreated rats or as a solution in 5% NaHCO3 to lansoprazole-pretreated rats. 5-ASA solubility in vitro was higher at pH < 2 and pH > 7. In rats, the 5-ASA and AC-5-ASA were detected mostly in the small intestine at 3 h and in the colonic region at 8 h after administration. The dosing vehicle (suspension or solution) and lansoprazole pretreatment did not significantly affect the pH of the luminal fluid in rats or the 5-ASA distribution in membranes. The 5-ASA distribution in membranes in the proximal intestine was found to be restricted by the intrinsic regional luminal pH, low solubility, and saturable membrane permeability. Unabsorbed 5-ASA in the proximal intestine was delivered to the distal intestine. The higher the oral dose of 5-ASA, the more 5-ASA may be delivered to the distal intestine due to the restricted absorption in the small intestine.

Nonlinear force transfer characteristic analysis of active suspension for emergency rescue vehicles

This paper presents a nonlinear force transfer model for active suspension. First of all, according to the motion analysis of Mcpherson suspension, the force transfer characteristics between the three-dimensional force on tire contact point and the output force of suspension cylinder was studied. Then the friction force between the piston rod and the cylinder body was analyzed. Combined with the force transfer characteristics and the friction force, the nonlinear force transfer model was established which expressed the relationship between the pressure of cylinder cavities and the three-dimensional force at the tire contact point. Finally, the test is carried out on the three-axis emergency rescue vehicle, and the results show that, compared with the simplified active suspension model the ME and RMSE values of the force transfer model are reduced by 93.97%, and 78.31%, respectively. The nonlinear force transfer model can provide more accurate data support for the operation and control of active suspension system.

Optimization of electric vehicle suspension parameters using improved artificial fish swarm algorithm

This study proposes a solution to reduce vertical vibrations and body pitching in response to random road surface excitations. To achieve these objectives, a half-vehicle model of an electric vehicle (EV) is developed to determine optimal parameters for both the EV suspension system and the driver's seat suspension system. An Improved Artificial Fish Swarm Algorithm (IAFSA) is implemented using MATLAB software to optimize these suspension parameters. The optimization aims to minimize the root mean square (RMS) values of three objective functions: vertical driver's seat acceleration (aws), vertical vehicle body acceleration (awb), and pitching vehicle body acceleration (awphi). The optimization results reveal that the values of these three objective functions decrease when using the optimized suspension parameters compared to the original suspension settings. Specifically, the aws, awb and awphi values are reduced by 15.44%, 11.46%, and 8.65%, respectively, when the vehicle travels on an ISO road class B at a speed of 20 m/s with a full load. Furthermore, the peak amplitude values of as, ab, and aphi in the frequency domain are also reduced with the optimized suspension parameters compared to the original settings under the specified conditions.

State estimation of magnetorheological suspension of all-terrain vehicle based on a novel adaptive Sage–Husa Kalman filtering

Abstract For the magnetorheological suspension control system of all-terrain vehicles (ATVs), state estimation is an effective method to obtain system feedback signals that cannot be directly measured by sensors. However, when confronted with modeling errors and sudden changes in sensor noise during complex road driving, conventional estimation methods with fixed parameters encounter challenges in accurately estimating the states of ATV suspension system. To address this issue, this paper introduces a novel adaptive Sage–Husa Kalman filter (ASHKF) algorithm to estimate the sprung and unsprung velocity of ATV suspension system. The algorithm uses exponential weighting function and gradient detection function to adaptively adjust the attenuation coefficient according to the driving conditions of the ATV, thereby realizing real-time correction of the covariance matrix of the prediction error. Ultimately, through simulation and real-vehicle testing, it is demonstrated that the designed ASHKF is able to effectively improve the state estimation accuracy of the speed signal of the suspension system under off-road driving conditions with low-frequency noise and outlying disturbances, and the accuracy is improved by 62.70% compared with that of the conventional Sage–Husa Kalman filter (SHKF).

Markov multi-fault tolerance control of intelligent suspension in blind scenes

This paper focuses on insufficient perception in blind scenes and the failures of the actuator and sensor of vehicle suspension. The safe speed is designed and the fault-tolerant strategy based on the observer is designed when the actuator and sensor fail simultaneously. A speed planning strategy to ensure that vehicles operate at a safe speed is proposed. The Markov suspension fault jump model considering the suspension sensor and actuator faults is established. Based on the fault estimation obtained by the fault observer, a fault tolerance control strategy of sensor signal reconstruction and actuator fault compensation is adopted. The measurement index for evaluating fault tolerance effectiveness has been established, and an exploration of fault tolerance control is conducted across various fault levels, to identify the preferred fault tolerance strategies corresponding to different levels of fault tolerance. The simulation results show that the designed speed control strategy can improve vehicle safety by decelerating in advance, the fault observer is capable of accurately estimating the true values of actuator and sensor faults. The simulation and vehicle test results demonstrate that similar suspension performance has been obtained by fault-tolerant control strategy and preferred fault tolerance under different fault tolerance levels compared with normal fault tolerance.

Model-Free Adaptive Control of an Active Half-Vehicle-Seat System Coupled with a Nonlinear Energy Sink Inerter (NESI)

In order to reduce vehicle vibration and improve vehicle ride comfort and handling stability, a nonlinear energy sink inerter (NESI) is designed by combing an inerter and nonlinear energy sink (NES) for use in the seat suspension and vehicle suspension for the half-vehicle-seat (HVS) system; furthermore, a model-free adaptive control (MFAC) method based on the genetic algorithm is proposed to enhance the dynamic performance of the passive HVS system. The dynamic model of the active HVS system coupled with NESI using the MFAC method is established; its dynamic responses under pavement random and shock excitations are acquired using the numerical method and the dynamic performance is evaluated by seven evaluation indicators. The efficacy of the MFAC method is demonstrated through comparative analysis with the original passive HVS system, the HVS system coupled with NESI, and the active HVS system coupled with NESI using the proportional integral derivative (PID) control method. In addition, the influence of the installed position of MFAC on the dynamic performance of the active HVS system coupled with NESI is examined. The results show that for the active HVS system coupled with NESI using the MFAC method, compared with the other three HVS systems, the root mean square (RMS) values of the vehicle body vertical acceleration, vehicle body pitch acceleration, seat vertical acceleration, and front and rear suspension dynamic travel under pavement random excitation are smaller, the corresponding peak amplitudes under pavement shock excitation reduce, and the vibration attenuation time shortens; the RMS values of the front and rear dynamic tire loading under pavement random excitation are slightly smaller, the corresponding peak amplitudes under pavement shock excitation increase, and the vibration attenuation time decreases, which reflects the best dynamic performance among the four HVS systems and shows the effectiveness of the MFAC method. Furthermore, the control effect of the MFAC method is the best when it acts both on the seat and vehicle suspensions.

Determination and Characterization of Optimum Non-Linear Damping in Vehicle Suspension System

Determination and Characterization of Optimum Non-Linear Damping in Vehicle Suspension System

Physicochemical and Microbiological Stability of Ursodiol Oral Compounded Suspensions.

In the United States, ursodiol is commercially available as solid dosage forms, which represents a problem for children who cannot swallow capsules or tablets. There is a lack of an age-appropriate formulation for ursodiol, and the extemporaneous preparation of an oral suspension with an extended beyond-use-date (BUD) may represent a good therapeutic alternative for the pediatric population. However, all pharmacists need validated stability studies to prepare oral liquids with high quality and safety. Oral compounded suspensions for ursodiol 20 to 60 mg/mL were prepared by adding the contents of ursodiol 300-mg commercial capsules (Actavis, KVK Tech, and Mylan) to a proprietary oral suspending vehicle. The BUD of the oral compounded suspensions was determined by using a valid, stability-indicating analytical method. The physical characterization consisted of observing all samples for appearance and color, and testing for pH. Microbiological stability testing followed the United States Pharmacopeia (USP) Chapter 51: Antimicrobial Effectiveness Testing. The ursodiol oral compounded suspensions exhibited a homogeneous white color and the pH did not change significantly. The potency of the oral suspensions remained within ±10% of the specifications. Considering the microbiological characterization, there was no growth of challenge microorganisms throughout the study for all samples. This study demonstrates that ursodiol (Actavis, KVK Tech, and Mylan) is physically, chemically, and microbiologically stable in the oral suspending vehicle at room temperature for up to 6 months.

Electro-magnetic Suspension System in Vehicles

Electro-magnetic Suspension System in Vehicles

Self-Sensing Approach for Semi-Active Control of Variable Damping Electromagnetic Suspension System

This paper combines the Kalman filter observer with self-sensing technology and integrates it into the electromagnetic damper (EMD), estimating the displacement and velocity of the EMD based on the three-phase voltage generated by the permanent magnet synchronous motor (PMSM). The self-sensing performance of the EMD is verified through theoretical analysis and experimental results. A vehicle suspension vibration control system composed of one-quarter vehicle electromagnetic suspension (EMS), a acceleration damping driven control (ADDC) algorithm, and a vibration excitation platform is established to test the vibration control performance of the self-sensing EMS. The experimental results show that under random road excitation, compared to passive suspension, the self-sensing-based ADDC reduced the vehicle vertical acceleration of the vehicle suspension, with a 28.92% decrease in the root mean square (RMS) value of the vehicle vertical acceleration. This verifies the effectiveness of the self-sensing capability of the EMS system. Incorporating self-sensing technology into the EMS system improves the vibration reduction performance of the suspension.

Suspension height tune-up with constant stiffness properties through motor-driving double-gas-chamber hydro-pneumatic strut: Experimental study and modeling.

In vehicle suspension, it is important to achieve continuous height adjustment to reduce the possibility of unstable and off-tracking caused by uneven postures. It is usually solved by air suspension, in which the dynamic properties will change under the adjusting process and these changes are not conducive to control. Considering the above, in this paper a double-gas-chamber hydro-pneumatic strut (DHPS) with the constant and/or predicted stiffness during continuous height adjustment, as masses (oil and gas) conversation are guaranteed in the whole system, which is achieved by volume variation of auxiliary gas chamber through motor-driving piston, is proposed. The dynamic properties and mathematic model of the proposed DHPS are investigated and established through bench test applying to the designed prototype. The system response speed has been evaluated through experimental data that for harmonic test the system can reach the stable condition in 1 (2) cycle subjected to 50mm/s (25mm/s) motor-driving piston moving speed. Finally, a typical quarter-car model is utilized to evaluate the performance of the proposed DHPS. It has been shown that the system takes 0.40s and 0.50s (200mm/s moving speed), and 0.76s and 1.36s (40mm/s moving speed) subjected to step test (25 and 50 mm), respectively.

THE METHOD OF THE VEHICLE SUSPENSION SYSTEM DAMPING ELEMENT LOAD CHARACTERISTIC SYNTHESIZING

BACKGROUND. Nowadays the question of increasing the smoothness of running of vehicles is actual. The main way of solution is to carry out synthesis of design parameters of suspension systems. For carrying out such works and obtaining the most satisfactory characteristics new methods of synthesis of load characteristics of vehicle suspension devices are necessary. AIMS. The purpose of this work is to develop a new method of synthesizing the characteristic of the shock absorber of the vehicle suspension system. METHODS. The study solves the problem of controlling vibrations on their propagation paths by determining the required load characteristic of a vehicle suspension damping device. Analytical methods and simulation modeling methods are applied in the solution process. RESULTS. As a result of the work a new method based on the construction of the zone of permissible damping values and selection of the characteristic on its basis has been created. On the basis of the obtained method a number of nonlinear characteristics of the damping element of the primary system of vehicle suspension and selection of the most suitable one from the point of view of smoothness of motion were formed. CONCLUSIONS. As a result of the work a new method of synthesizing the damping characteristic of the shock absorber has been obtained. As a result of comparative evaluation the efficiency of the new method is confirmed. For the considered object of research the difference in smoothness of motion amounted to 25%.

Inertial mass modeling and compensation for an energy-harvesting vehicle suspension system with limited-DOF parallel mechanisms actuator

An energy-harvesting suspension can improve the energy efficiency of vehicle. By introducing a lower-mobility parallel mechanism as motion transfer in the energy-harvesting suspension, the stiffness of the system is significantly improved. However, the overlage equivalent of inertial mass make the system is difficult to control and imped the development of this kind of suspension. To solve the problem, an equivalent linearization model to calculate the nonlinear inertial mass of low-DOF (Degree Of Freedom) parallel mechanism actuator is studied firstly. Furthermore, a 2-DOF 1/4 suspension system dynamic model that includes inertial mass is proposed to analyze the vehicle acceleration, dynamic tire load, and dynamic stroke. On this basis, the linear-quadratic Gaussian (LQG) controller is adopted to compensate the inertial mass of the suspension to improve the system performance. Results show that the proposed model accurately reflects the characteristics of the suspension inertial mass, the root-mean-square (RMS) value of the vehicle body acceleration and suspension dynamic stroke through compensation controller is reduced by 33.4% and 30.89%, respectively. Moreover, the RMS of the dynamic tire load is reduced by 3.06%, and the system stability is improved significantly.

Performance Characteristics of a Compact Core Annular-Radial Magnetorheological Damper for Vehicle Suspension Systems

The magnetorheological (MR) damper is a by-wire system capable of providing variable damping stiffness by responding to an apparent magnetic field. In response to the magnetic field application, the magnetorheological fluid (MR fluid) exhibited altered behavior within the damper. Typically, a damper’s internal and external valves operate in flow mode, where the flow is regulated by controlling the magnetic field. This study aims to investigate the performance characteristics of a small core annular and radial magnetorheological valve (SCARMV) designed for applications in vehicle suspension systems. The proposed design of the simplified MR valve is based on a meandering-type valve composed of multiple valve cores that have been simplified to a single core. Dynamic testing was performed on the proposed valve, which features a single rod tube damper, to investigate the damping force characteristics by varying currents and frequencies. The characteristics of the measured damping force were compared to the calculated damping force based on the pressure drop calculation and the FEMM simulation of magnetic flux. By increasing the stroke length of the valve travel is set to 10 mm at a current input of 0 A to 1.0 A, the maximum output of the MR valve damping force was approximately 1.57 kN. In addition, a mathematical model of SCARMV is presented and compared to the experimental data. Therefore, based on the experimental results, it was concluded that the usability of a compact core MR valve is reliable. However, more in-depth studies are required before these dampers can be applied to vehicle suspension systems.