Symmetry Control of Comfortable Vehicle Suspension Based on H∞

Suspension is an important part of intelligent and safe transportation; it is the balance point between the comfort and handling stability of a vehicle under intelligent traffic conditions. In this study, a control method of left-right symmetry of air suspension based on H∞ theory was proposed, which was verified under intelligent traffic conditions. First, the control stability caused by the active suspension control system running on uneven roads needs to be ensured. To address this issue, a 1/4 vehicle active suspension model was established, and the vertical acceleration of the vehicle body was applied as the main index of ride comfort. H∞ performance constraint output indicators of the controller contained the tire dynamic load, suspension dynamic stroke, and actuator control force limit. Based on the Lyapunov stability theory, an output feedback control law with H∞-guaranteed performance was proposed to constrain multiple targets. This way, the control problem was transformed into a solution to the Riccati equation. The simulation results showed that when dealing with general road disturbances, the proposed control strategy can reduce the vehicle body acceleration by about 20% and meet the requirements of an ultimate suspension dynamic deflection of 0.08 m and a dynamic tire load of 1500 N. Using this symmetrical control method can significantly improve the ride comfort and driving stability of a vehicle under intelligent traffic conditions.

Hybrid Sliding Mode Control of Full-Car Semi-Active Suspension Systems

With the advance in technology in driving vehicles, there is currently more emphasis on developing advanced control systems for better road handling stability and ride comfort. However, one of the challenging problems in the design and implementation of intelligent suspension systems is that there is currently no solution supporting the export of generic suspension models and control components for integration into embedded Electronic Control Units (ECUs). This significantly limits the usage of embedded suspension components in automotive production code software as it requires very high efforts in implementation, manual testing, and fulfilling coding requirements. This paper introduces a new dynamic model of full-car suspension system with semi-active suspension behavior and provides a hybrid sliding mode approach for control of full-car suspension dynamics such that the road handling stability and ride comfort characteristics are ensured. The semi-active suspension model and the hybrid sliding mode controller are implemented as Functional Mock-Up Units (FMUs) conforming to the Functional Mock-Up Interface for embedded systems (eFMI) and are calibrated with a set experimental tests using a 1/5 Soben-car test bench. The methods and prototype implementation proposed in this paper allow both model and controller re-usability and provide a generic way of integrating models and control software into embedded ECUs.

Physiological Reloading Recovers Histologically Disuse Atrophy of the Articular Cartilage and Bone by Hindlimb Suspension in Rat Knee Joint

Objective This study aimed to clarify physiological reloading on disuse atrophy of the articular cartilage and bone in the rat knee using the hindlimb suspension model. Design Thirty male rats were divided into 3 experimental groups: control group, hindlimb suspension group, and reloading after hindlimb suspension group. Histological changes in the articular cartilage and bone of the tibia were evaluated by histomorphometrical and immunohistochemical analyses at 2 and 4 weeks after reloading. Results The thinning and loss of matrix staining in the articular cartilage and the decrease in bone volume induced by hindlimb suspension recovered to the same level as the control group after 2 weeks of reloading. The proportion of the noncalcified and calcified layers of the articular cartilage and the thinning of subchondral bone recovered to the same level as the control group after 4 weeks of reloading. Conclusions Disuse atrophy of the articular cartilage and bone induced by hindlimb suspension in the tibia of rats was improved by physiological reloading.

A Methodology to Investigate Powered Two-Wheeler Rider’s Comfort over Road Sections with Skew Superelevation

The proper surface water drainage not only affects vehicle movement dynamics but also increases the likelihood of an accident since inadequate drainage is associated with potential hydroplaning and splash and spray driving conditions. Nine solutions have been proposed to address hydroplaning in sections with inadequate drainage e.g. augmented superelevation and longitudinal slope, reduction of runoff length, and skew superelevation. The latter has been extensively implemented in highways recently, enhancing the safety level in the applied road segments regarding the effective drainage of the rainwater. However, the concept of the skew superelevation has raised concerns regarding the level of driver’s comfort when traveling over skew superelevation sections particularly with high speeds. These concerns were alleviated through the concept of the round-up skew superelevation which reduces both the lateral and the vertical acceleration imposed on the drivers and hence, improves comfort and traffic safety. The present study investigates the behaviour of power two-wheeler riders since they are susceptible to any changes on the pavement surface and therefore a comparison between the traditional superelevation practice and the skew superelevation concept is of paramount importance. The methodology is based on the utilization of sophisticated software to design the model of the road for several values of longitudinal slopes. Based on the values of the slopes and the use of mathematical equations, the accelerations imposed on the wheel of the motorcycle were calculated. Since the final aim of the study is the influence of the skew superelevation to the rider, it was deemed necessary to convey the calculated accelerations from the wheel to the rider. That was accomplished by implementing the quarter car suspension model adjusted to the features of two-wheeler vehicles. Finally, the accelerations derived from this process evaluated according to specific thresholds based on the literature which correspond to certain levels of comfort. The most important conclusion drawn is that the comfort of the riders is not dependent to a great extent on the form of the road gradient because the vertical acceleration imposed on the riders took similar values regardless of the value of the longitudinal slope.

Optimal Design and Analysis of Intelligent Vehicle Suspension System Based on ADAMS and Artificial Intelligence Algorithms

A complete suspension model is established, and the suspension system is simulated and optimized. The method of suspension system establishment and simulation is explained in detail, and the influence of suspension parameter changes on vehicle handling and stability is analyzed in detail. The dynamic simulation analysis of wheel parallel runout test was carried out on the system, and the suspension system was optimized by artificial intelligence algorithm. The research results provide a technical basis for the design of automobile suspension.

Adaptive Kalman Filter with L2 Feedback Control for Active Suspension Using a Novel 9-DOF Semi-Vehicle Model

In order to further improve driving comfort, this paper takes the semi-vehicle active suspension as the research object. Furthermore, combined with a 5-DOF driver-seat model, a new 9-DOF driver seat-active suspension model is proposed. The adaptive Kalman filter combined with L2 feedback control algorithm is used to improve the controller. First, a discrete 9-DOF driver seat-active suspension model is established. Then, the L2 feedback algorithm is used to solve the optimal feedback matrix of the model, and the adaptive Kalman filter algorithm is used to replace the linear Kalman filter. Finally, the improved active suspension model and algorithm are verified through simulation and test. The results show that the new algorithm and model not only significantly improve the driver comfort, but also comprehensively optimize the other performance of the vehicle. Compared with the traditional LQG control algorithm, the RMS value of the acceleration experienced by the driver’s limb are, respectively, decreased by 10.9%, 15.9%, 6.4%, and 7.5%. The RMS value of pitch angle acceleration experienced by the driver decreased by 6.4%, and the RMS value of the dynamic tire deflection of front and rear tire decreased by 32.6% and 12.1%, respectively.

Modeling and controlling a quarter-vehicle active suspension model

This paper presents an application of the LQR active suspension control algorithm for a vertical planar oscillation model developed for ¼ of a vehicle. The wheel smoothness and dynamics with the road surface are two parameters to provide control signals. A simulation model is developed here based on MATLAB software to compare and evaluate the LQR active suspension model with the passive suspension. The results obtained here shows an improvement for a number of parameters when utilizing the active suspension model including fluctuating amplitude; oscillation damping time; the displacement acceleration of the active suspension body.

Design, Modeling and Ride Analysis of Energy-Harvesting Hydraulically Interconnected Suspension

This paper introduces a novel energy-harvesting hydraulically interconnected suspension (EH-HIS) to improve the riding comfort and road handling performance for off-road vehicles while harvesting the vibration energy traditionally dissipated into heat by the oil shock absorbers. To understand the system, we built a model of the off-road vehicle equipped with the EH-HIS and conducted the performance analysis. The system model is established based on the pressure drop principle and validated by commercial simulation software AMESim. The damping characteristic and energy harvesting performance have been investigated based on the mathematical suspension model. Further, a thorough analysis is implemented to compare the dynamic responses of the vehicle equipped with the traditional suspension and EH-HIS under different driving speeds and road classes. Results show that the EH-HIS system can provide tunable asymmetric damping from 3134 Ns/ to 7558 Ns/m, which covers most of the damping range of the off-road vehicles. The average regenerative power of the half EH-HIS system reaches 438 watts, and the corresponding hydraulic efficiency reaches 19%, at a vibration input of 2 Hz frequency and 30 mm amplitude. The ride analysis shows that the vehicle equipped with the EH-HIS system on the D class road has good handling stability and better ride comfort over the traditional suspension.