Random Road Input Research Articles

Research on Coordinated Control of Vehicle Inertial Suspension Using the Dynamic Surface Control Theory

In the process of driving, the steering, braking, and driving conditions and different road conditions affect the vibration characteristics of the vehicle in the vertical, roll, and pitch directions. These factors greatly impact the riding comfort of the vehicle. Among them, the uneven distribution of vertical load between the left and right or the front and rear suspension is one of the important factors affecting the performance indicators of the vehicle’s roll angle acceleration and pitch angle acceleration. In order to improve the ride comfort of the vehicle in vertical, roll, and pitch motion, the inerter is introduced in this paper to form a new type of suspension structure with the “spring-damping” base element, inertial suspension. It breaks away from the traditional “spring-damping” base element of the inherent suspension structure. In this paper, the mechatronic inerter is taken as the actual controlled object, and the inertial suspension structure is considered as the controlled model based on the dynamic surface control theory and the pseudo-inverse matrix principle. Thus, the coordinated control of the inertial suspension can be achieved. Under random road input, compared with passive suspension, the ride comfort performance indicators of the vehicle with inertial suspension based on dynamic surface control are significantly improved. Finally, a Hardware-in-the-Loop (HiL) test of the controller based on dynamic surface control is carried out to verify that the performance of the vehicle inertial suspension using the dynamic surface control algorithm had improved in terms of vehicle ride comfort. The error between the experimental results and the simulation results is about 8%, which verifies the real-time performance and effectiveness of the dynamic surface controller in the real controller.

A study of lateral trajectory tracking control under fused slip rate and road random inputs

To improve the maneuvering stability of uncrewed armored vehicles during emergency steering and obstacle avoidance under high-speed driving conditions in off-road undulating terrain, in this paper, we establish a 7DOF dynamics model based on the time-varying trajectory curvature for the lateral and vertical motion of the spring-loaded mass and the vertical jump of the unsprung mass. Also, we consider two slip motion states with tires in the linear zone and tire slip nonlinear zone based on the Dugoff model and use trip and non-trip rollover under random road input as rollover warning constraint, and conduct flat road DLC test, 20° side slope test, JLTV twisted road respectively by Carsim-Simulink jointly according to NATO double shift line test standard. The improved LTV-MPC algorithm solves the optimal tracking control sequences of 2DOF and 7DOF kinetic models, and the trajectory tracking is completed, compared, and analyzed.

Research on control strategy of seven-DOF vehicle active suspension system based on co-simulation

In recent years, since the unique advantages in automotive structures, the vehicle active suspension systems have received widespread attentions. A good active suspension system can reduce the vibration and improve the overall performance of the vehicle. Therefore, the design of the controller for the active suspension system to perform autonomous adjustment plays a vital role in vehicle comfort and safety. For the active suspension of the seven-DOF sport utility vehicle (SUV) model, this paper takes the vehicle body acceleration, tire dynamic load and suspension dynamic travel as the indicators to evaluate the performance, and the proportional-integral-derivative (PID) controller is designed to improve the performance of the vehicle active suspension system. Based on the software of MATLAB/Simulink and Carsim, a closed-loop co-simulation model diagram is established, which includes a PID controller module. Meanwhile, the random road input model and the whole vehicle model are constructed in Carsim. Finally, at the speeds of 70, 90, and 120 km/h, the active suspension system under the designed PID controller is simulated and compared with the passive suspension system. The simulation results show that the active suspension system based on PID controller can effectively improve the overall performance of the vehicle, and then the comfort and safety of the vehicle can be further enhanced.

Research on predictive coordinated control of ride comfort and road friendliness for heavy vehicle ISD suspension based on the hybrid-hook damping strategy

With the appearance of inerter, the ISD suspension composed of “Inerter-Spring-Damper” opens up a new direction for efficient coordination of ride comfort and road friendliness for heavy vehicles. In this paper, a reference model based on the hybrid-hook damping strategy is proposed, and the mechatronic inerter is used as an active suspension force generator in the actual controlled model. Then, the coordinated control of the vehicle ISD suspension model is realized by the model predictive control (MPC) approach. The test results show that, the RMS values of the body acceleration and dynamic tire load of the controllable ISD suspension is smaller than the traditional passive and passive ISD suspension under the sinusoidal road inputs. Under the random road input, compared with the traditional passive suspension, the controllable ISD suspension has improved the RMS value of the body acceleration by 26.61%, and the road damage coefficient has been improved by 20.13%. Experiments show that the controllable ISD suspension of heavy vehicles based on the hybrid-hook damping strategy has comprehensive improvement of vehicle ride comfort and road friendliness.

Novel 2D strain-rate-dependent lamina-based and RVE/phase-based progressive fatigue damage criteria for randomly loaded multi-layer fiber-reinforced composites

Two implicit progressive fatigue damage models that rely on new equivalent-damage and equivalent-stress criteria are presented for the prediction of various failure modes of the composites. The criteria are coupled with lamina-based and representative-volume-element-based damage progression approaches. The common concepts of residual strength and residual stiffness are revisited and modified. A fatigue life assessment algorithm that incorporates the strain-rate-dependence of the fatigue strengths and stiffnesses, and random and asynchronous changes of the stress components, distinct mean values, and phase shifts of the stress components is employed. New ideas and new post-processing procedures are employed in the current research. It is the first time that the significant impacts of the strain-rate-dependence of the properties of the composites on stress and fatigue life analyses are investigated. Results of the proposed fatigue criteria are first implemented to a composite plate with a complex lamination scheme under a random transverse load and the predicted fatigue lives are verified by the experimental results. Then, these criteria are implemented to a composite chassis frame of an SUV car under realistic random road inputs and the theoretical results are verified by the experimental results. Results confirm the significant role of the strain-rate-dependence effects on the fatigue lives.

Performance Improvement of Suspension Characteristics by Implementation of Active Suspension System in Two Wheelers

New and better two-wheel models have increased demand today, with increased protection, comfort and performance. The human body gets exhausted, which contributes to back pain and neck pain because of the excessive use of bikes, wrong riding positions, poor weather and suspension system issues. The systems engineer would focus on the design of the vehicle suspension mechanism to minimise human discomfort. This research aims to study the feasibility of implementing a suspension system with active suspension for a two-wheeler by way of numerical modelling, simulation and analysis. First of all, the active suspension system for a 2 DOF system is modelled and analysed. The analysis done is frequency response analysis and time-domain analysis. The time-domain analysis is done using two road inputs; one is a bump input, which is designed according to the standards, and the other is a random road input. Then the two-wheelers were modelled as a 4 DOF model. The controller is modelled using optimal control theory. A linear quadratic regulator (LQR) controller is used because the system is assumed to have linear characteristics and the cost function of the system is quadratic. It is observed that suspension characteristics are improved by using the active suspension system in two-wheelers.

Design and development of MR damper for two wheeler application and Kwok model parameters tuning for designed damper

Magnetorheological dampers have been the interest of many researchers for a few decades for the reason of being an effective and rapidly progressing technology in the field of semi-active controlled suspension. The dynamic behaviour of these devices with nonlinear hysteresis is quite a complicated phenomenon. Hence, this paper aims at the design, modelling and simulation of a custom-made MR damper for a two-wheeler vehicle. The Kwok model has been chosen to mathematically model the MR damper. The model parameters have been optimised by minimizing the error difference between experimental and model-generated force results. A PID control is designed to control the damper effectively depending on the deflection of the damper. The two-wheeler vehicle modelled with four degrees of freedom is coupled with a mathematical model of MR damper in front and rear suspension. Further, the dynamic analysis has been performed in MATLAB/Simulink considering random road input for different velocities and current input conditions. The improved performance of MR damper was observed in suppressing road irregularities using a PID controller. As an implementation part of the work, the developed damper has been implemented in a two wheeler vehicle for performance evaluation at on-road testing conditions. The results showed significant improvement in damper performance with increment of constant current controlling MR dampers.

Ride comfort analysis of driver seat using super twisting sliding mode controlled magnetorheological suspension system

In order to improve the ride comfort of the driver, a higher-order Sliding Mode Controller was proposed in this study for a semiactive magnetorheological (MR) suspension system. The work is mainly focused on improving the ride comfort of the driver with simultaneous improvement in road holding capability of the vehicle and to study the effects of using Super Twisting Sliding Mode Controller (STSMC) in a quarter car with driver seat model. The modified Bouc-Wen model was simulated using MATLAB/Simulink software and the STSMC was adopted to control the voltage variation in MR damper using Continuous State Control (CSC) algorithm. The controller and the suspension system parameters were analysed in time domain with random road inputs. Fast Fourier Transform (FFT) analysis was also carried out to show the effectiveness of the controller towards improving the driver seat comfort. The STSMC-controlled MR damper was used as a primary suspension and the effectiveness of its controllability was compared with passive suspension system. The uncontrolled MR suspension system was also analysed in order to verify the fail-proof advantage of the MR damper. From the results, it was found that the ride comfort was extremely improved when STSMC controller was used than when the uncontrolled MR and passive suspension systems were employed. The uncertainty of the STSMC was verified for different passenger masses and it achieved a robust control over load variation. The selected STSMC was validated with the first-order Sliding Mode Controller and the results were discussed in terms of time-domain analysis.

Nonlinear Interval Optimization of Asymmetric Damper Parameters for a Racing Car

Uncertainties in parameters can affect racing car performance. In this study, a nonlinear interval suspension damping optimization method is proposed to improve the road holding of a racing car. To evaluate the dynamic responses of racing cars under a random road input and a bump input with interval uncertain parameters, a quarter car model with a two-stage asymmetric damper is established. Then, a quadratic approximation model with second derivative terms is developed by second-order Taylor series expansion and dimension reduction to calculate the nonlinear dynamic response of the vehicle. Interval analysis of the objective function and constraints is carried out using interval arithmetic to eliminate nesting optimization and make the optimization efficient. The results show that the proposed optimization method can improve road holding performance, effectively suppress the fluctuation range of the road holding performance evaluation index, and ensure the robustness of the design scheme.

Dynamic Response of a Semiactive Suspension System with Hysteretic Nonlinear Energy Sink Based on Random Excitation by means of Computer Simulation

This paper aims to investigate the property and behavior of the hysteretic nonlinear energy sink (HNES) coupled to a half vehicle system which is a nine-degree-of-freedom, nonlinear, and semiactive suspension system in order to improve the ride comfort and increase the stability in shock mitigation by using the computer simulation method. The HNES model is a semiactive suspension device, which comprises the famous Bouc–Wen (B-W) model employed to describe the force produced by both the purely hysteretic spring and linear elastic spring of potentially negative stiffness connected in parallel, for the half vehicle system. Nine nonlinear motion equations of the half vehicle system are derived in terms of the seven displacements and the two dimensionless hysteretic variables, which are integrated numerically by employing the direct time integration method for studying both the variables of vertical displacements, velocities, accelerations, chassis pitch angle, and the ride comfort and driver safety, respectively, based on the bump and random road inputs of the pseudoexcitation method as excitation signal. Simulation results show that, compared with the HNES model and the magnetorheological (MR) model coupled to the half vehicle system, the ride comfort and stability have been evidently improved. A successful validation process has been performed, which indicated that both the ride comfort and driver safety properties of the HNES model coupled to half vehicle significantly improved.

Dynamic Analysis of a Quarter Car Model with Semi-Active Seat Suspension Using a Novel Model for Magneto-Rheological (MR) Damper

Mathematical modeling of magneto-rheological damper has been an intriguing field of research ever since the invention of the device itself. An accurate magneto-rheological damper model results in development of an efficient current controller in a semi-active seat suspension system featuring magneto-rheological damper. Hence, a number of models have been put forward to accurately predict the magneto-rheological damper behavior. This paper presents another mathematical model for magneto-rheological dampers based on their equivalent damping. A commercially available magneto-rheological damper has been used for characterization in this study. The magneto-rheological damper behavior is characterized using two models, Bingham model and equivalent damping model. These models are then used to simulate the magneto-rheological damper in a quarter car model with four degree of freedom featuring semi-active seat suspension that is subjected to bump road input and random road input. The magneto-rheological damper model is supplied with current using two control logics, on–off Skyhook logic and Proportional Integral and Differential logic. The performance of the two models are compared based on driver mass response in each case of seat suspension model and computation time. The results show that equivalent damping model can represent the magneto-rheological damper behavior with sufficient accuracy while reducing computational time by 30% irrespective of type of road input or type of control logic implemented. The reduced computational time is an added advantage when magneto-rheological damper is used in real-time.

The ride comfort optimization of mining dump truck based on eight degree of freedom

The working environment of mining dumping truck is poor and in order to improve the vibration reduction effect of mining dump trucks, a vehicle damping adjustable semi-active suspension based on connected hydro-pneumatic suspension is proposed. The 8 DOF model of hydro-pneumatic suspension and complete vehicle was established for mining dump truck. The fuzzy PID control method is used to optimize the smoothness of the vehicle by controlling the vertical acceleration of the truck, pitch angle acceleration and seat vertical acceleration. The damping performance of semi-active suspension is analyzed by Matlab/Simulink software. The simulation results show that compared with the passive suspension under the condition of random road power spectrum input, the root mean square values of the vertical acceleration of the truck and the vertical acceleration of the seat of the semi-active suspension are reduced by 25.76% and 48.7%. At the same time, the effect of vehicle vibration reduction is also obvious under the different speeds.

Dynamic modeling and simulation of 4X4 wheeled vehicle

In view of the requirements of military vehicles for high-mobility off-road performance, the dynamic modeling of 4X4 wheeled armored vehicles was carried out. The dynamic model expression expressed in matrix form was derived, and the decoupling calculation was performed by Fourier transform. After that, the power spectral density function was used to characterize the random road input of the vehicle, and the coherence of each wheel excitation in the four-wheeled vehicle was analyzed to derive the coherence coefficient. Finally, the calculation method of vibration response of vehicles under typical roads was formed by programming analysis and reasonable algorithm, and it provided theoretical support for suspension vibration isolation performance design.

Performance Analysis of Fractional Order Terminal SMC for the Half Car Model with Random Road Input

The vehicle’s active suspension system is useful to reduce the vibration and to increase the travel quality. In this paper, the fractional order terminal sliding mode controller (FOTSMC) is proposed to reduce the head acceleration of the driver and passenger with the half car model. The seat suspension and primary suspension is helping the vehicle to reduce it’s vibration. The performance of the proposed SMC is compared with other SMCs and passive system. The performance of the primary suspension is compared with and without the seat suspension. From the simulated results, the FOTSMC performs better than the fractional order SMC, terminal SMC, and passive system for all the cases. The primary suspension with a saturation limit and seat suspension performs better than the performance of the primary suspension without the saturation limit.

Handling performance of tractor-semitrailers equipped with hydraulically interconnected suspension

This paper focuses on the contribution of a hydraulically interconnected suspension on the handling performance of a tractor-semitrailer. A hydraulically interconnected suspension model is integrated with a traditional tractor-semitrailer suspension for the purpose of study, and the hydraulically interconnected suspension system is first investigated through the bench test simulation to study its nonlinear and damping characteristic. Then a static rollover test, a steady-state circular test, a pulse steer input test, a pulse road input test and a random road input test are simulated in order to fully investigate the performance of a tractor-semitrailer with hydraulically interconnected suspension. The comparison analyses are conducted among two vehicles which are a fully loaded tractor-semitrailer without hydraulically interconnected suspension, an unloaded tractor-semitrailer without hydraulically interconnected suspension, a fully loaded tractor-semitrailer with hydraulically interconnected suspension and an unloaded tractor-semitrailer with hydraulically interconnected suspension. The obtained results show that the fully loaded tractor-semitrailer has enhanced handling performance, an improved steady-state rollover threshold and unchanged ride performance with the assistance of hydraulically interconnected suspension.

Suspension hybrid control for in-wheel motor driven electric vehicle with dynamic vibration absorbing structures

This paper presents a hybrid control strategy for suspension of the in-wheel motor (IWM) driven electric vehicle (EV) to improve vehicle ride comfort and reduce IWM vibration. A quarter vehicle model with the dynamic vibration absorbing structure (DVAS) is first developed. Different from the traditional suspension system, the DVAS uses an extra spring-damper system to achieve vibration reduction. The dynamics and boundary models for two commercially available and controllable dampers are then presented. Both dampers in the suspension and the DVAS are used to allocate the hybrid control force synthesized depend on the system responses. Simulation results for excitations of both random road and bump input are finally analyzed, and the proposed hybrid controller can simultaneously improve ride comfort and reduce IWM vibration compared to the traditional suspension system.

Integrated vehicle dynamics control using semi-active suspension and active braking systems

This article presents an integrated control of yaw, roll and vertical dynamics based on a semi-active suspension and an electronic stability control with active differential braking system. During extreme manoeuvres, the probability of vehicle rollover is increased and the stability of lateral and yaw vehicle motions is deteriorated because of the saturation of tyre forces. Furthermore, when the road excitation frequencies are equal to the natural frequencies of the unsprung masses, the resonance phenomena occurs, which causes some oscillations getting revealed on responses of the yaw and lateral vehicle dynamics. In these situations, the active braking alone cannot be helpful to improve the vehicle handling and stability, considerably. In order to overcome these difficulties, a coordinated control of the semi-active suspension and the active braking is proposed, using a fuzzy controller and an adaptive sliding mode controller, respectively. A non-linear full vehicle model with 14 degrees of freedom is established and combined with the modified Pacejka tyre model. As the majority of vehicle dynamics variables and the road profile inputs cannot be measured in a cost-efficient way, a non-linear estimator based on unscented Kalman filter is designed to estimate the entire vehicle dynamics states and the road unevenness. Simulation results of the steering manoeuvres on the random road inputs show that the proposed chassis system can effectively improve the vehicle handling, stability and ride comfort.

MR-SAS and electric power steering variable universe fuzzy PID integrated control

In order to solve the problem of MR-SAS and electric power steering (EPS) integrated control, the suspension and steering system integrated dynamic model was established, and the variable universe fuzzy PID integrated controller was designed. Due to the difficulty of self-adaptive and the superiority of compound control of fuzzy control, the variable universe fuzzy PID compound controller based on fuzzy inference was designed. The fuzzy on–off control based on trapezoidal membership function was used to the fuzzy control and PID control. And the random road input and steering wheel angle step input simulation experiment was carried out in the integrated system. Compared with the passive system and separate control, experimental results show that the integrated control system has obvious superiority.

A mixed control system for active suspension for off-road vehicles

Since the passive suspension system is not enough for creating good compromise between road handling and ride comfort for off-road vehicles, this paper presents a study on the application of an active suspension system. In this work, a neuro-fuzzy controller (NFC) is developed for two and three-axle half-car off-road vehicle models. A fuzzy logic controller (FLC) is employed as a benchmark for the NFC. The system designed for this study takes in two types of road disturbances as inputs, namely pothole and random road inputs. The sprung mass vertical and pitch accelerations are the criteria employed for the evaluation of the ride comfort, while the tyre deflection is used for the road handling. The results demonstrate that the NFC has a superior performance over the FLC in creating excellent ride comfort and good road handling without compromising the rattle-space requirement. On the other hand, the NFC requires higher actuation forces than the FLC as it gives a better performance that requires more control effort.

Improved design of dynamic vibration absorber by using the inerter and its application in vehicle suspension

Inerter is a recently proposed mechanical element with two terminals. The novelty of this paper is to present the improved design which aims to add traditional dynamic vibration absorber to the vehicle body by using the inerter. Based on this background, a new vehicle suspension structure called ISD suspension, including the inerter, spring and damper has been created. A dual-mass vibration model including the ISD suspension is considered in this study. Parameters are obtained by using the genetic optimizing algorithm. The frequency-domain simulation confirms that the ISD suspension can effectively improve the damping performance of the suspension system, especially at the offset frequency of the vehicle body, which is consistent with the feature of the dynamic vibration absorber added to the vehicle body mass. At last, a prototype ball screw inerter has been designed and the bench test of a quarter-car model has been undertaken. Under the conditions of the random road input, the vehicle ride comfort evaluation of body acceleration RMS value decreases by 4% at most, the suspension deflection RMS value decreases by 16% at most, the tire dynamic load RMS value decreases by 6% at most. Power spectral density results also indicate that the ISD suspension has superior damping performance than passive suspension which proves that the proposed ISD suspension is deemed effective.