Modern suspension systems for automotive vehicles and their test methods

This article provides a discussion on various solutions used in modern suspension systems of automotive vehicles. The mechanical dependent suspension system and some solution of adaptive, semi-active and active suspension system has been described. The paper also presents shortly test methods used to evaluation of technical conditions of this system

Comparison of different gas models to calculate the spring force of a hydropneumatic suspension

When developing any simulation model some compromise must be made between computational efficiency and the accuracy of the model. This study compares the performance of three ideal gas (IG) law variations (IG with the energy equation (EE), isothermal and adiabatic), and two real gas approaches (Benedict Webb Rubin (BWR) equation with and without the EE) to model the spring force of a hydropneumatic suspension. These models are compared with experimental data obtained from laboratory tests on a single hydropneumatic suspension unit. Both the BWR and IG models with the EE offer a significant improvement in correlation compared to the models without the EE. The real gas BWR approach offers a small improvement over the IG approach under the test conditions. The best (BWR with EE) and worst (IG isothermal) models are then used to model the spring forces in a full vehicle model of a 4 × 4 Sports Utility vehicle (SUV). The data is again compared with experimental results and the BWR model with the EE correlates significantly better than the IG isothermal model. It is thus concluded that the inclusion of the EE will yield significantly better results and it should only be omitted if the parameters investigated are not sensitive to errors in the spring model.http://www.elsevier.com/locate/jterrahb201

Design of Cab Suspensions and Semi-Active Seat Damping Control Strategies for Tractor Semi-Trailers

This thesis uses a high fidelity vertical plane ride model of the tractor semi-trailer to study the effect of different cab design configurations and semi-active seat damper control strategies on the driver’s ride comfort. The secondary suspensions of a tractor have been an area of particular interest because of the considerable ride comfort improvements they provide. A gap exists in the current engineering domain of an easily configurable high fidelity low computational cost simulation tool to analyze the ride of a tractor semi-trailer. A 15 degree of freedom model of the tractor semi-trailer was used to develop a simulation tool in the Matlab/Simulink environment. The simulation tool developed was verified against TruckSim. The contributions of the different modes of vibration to the ride comfort were analyzed. It is shown in this work that the ride at the driver’s seat can be significantly improved by relocating the cab mounts near the nodes of the 1st mode of bending of the tractor frame and by employing a full cab suspension. The developed simulation tool was used to quantify the improvements in the driver ride comfort. To develop seat isolation systems, the truck seat was modeled as a base excited 1 d.o.f. system. It is shown in this work that two optimal solutions exist depending on the spatial characteristics of the base excitation. One of the optimal solutions can be physically realized in the form of a passive spring and a passive damper in parallel. The other optimal solution can be approximated by a passive spring and a continuously variable damper in parallel. A fuzzy logic based switch mechanism was developed to switch between two realizations of the optimal solutions. A recursive least square estimator was developed to estimate the seat load and the stiffness of the spring using the same signals as the controller thus allowing universal application of the seat damper controller. The resultant controller is shown to provide the best ride comfort over various types of road surfaces. A model predictive controller for the seat damper was also developed for this work. A novel method was developed to model the bounds on the seat suspension stroke as hard constraints of the optimization problem. An efficient scheme was developed to include the frequency weighted acceleration in the performance index of the optimization problem. It is shown in this work that the MPC based seat damper controller provides better ride comfort in some specific scenarios. This work contributes towards the furthering the knowledge-base of the issues encompassing the ride quality of a tractor semi-trailer. The efficacy of the developed tractor semi-trailer ride simulation tool as a design and analysis tool is presented in this work

Slow active suspension control for rollover prevention

Rollover prevention in Sports Utility Vehicles (SUV‟s) offers a great challenge in vehicle safety. By reducing the body roll angle of the vehicle the load transfer will increase and thus decrease the lateral force that can be generated by the tires. This decrease in the lateral force can cause the vehicle to slide rather than to roll over. This study presents the possibility of using slow active suspension control to reduce the body roll and thus reduce the rollover propensity of a vehicle fitted with a hydro-pneumatic suspension system. The slow active control is obtained by pumping oil into and draining oil out of each hydro-pneumatic suspension unit individually. A real gas model for the suspension units as well as for the accumulator that supplies the oil is incorporated in a validated full vehicle Adams model. This model is then used to simulate a double lane change manoeuvre performed by a SUV at 60 km/h and it is shown that a significant improvement in body roll can be obtained with relatively low energy requirements. The proposed control is successfully implemented on a Land Rover Defender test vehicle. A Proportional-Derivative (PD) controller is used to control on-off solenoid operated valves and the flow is adjusted using the lateral acceleration as a parameter. Experimental results confirm that a significant improvement in body roll is possible. AFRIKAANS : Omrolvoorkoming in Sportnutsvoertuie bied geweldige uitdagings in terme van voertuigveiligheid. Deur die rolhoek van die voertuig te verminder word die laterale lasoordrag verhoog en word die laterale krag wat die bande kan genereer minder. As die laterale krag genoeg verminder sal die voertuig eerder gly as omrol. Die studie ondersoek die moontlikheid om stadig-aktiewe suspensiebeheer op 'n voertuig met 'n hidropneumatiese suspensie te gebruik om bakrol te verminder en dus die omrolgeneigdheid van die voertuig te verlaag. Die beheer word toegepas deur olie in elke hidropneumaties suspensie-eenheid individueel in te pomp of te dreineer. 'n Werklike gas model word gebruik om die supensie-eenhede asook die akkumulator, wat die olie aan die suspensie voorsien, te modeleer. Hierdie modelle word in 'n gevalideerde volvoertuig ADAMS model geïnkorporeer en 'n dubbel laanverwisseling word gesimuleer teen 60 km/h. Die resultate toon dat 'n beduidende verbetering in die rolhoek moontlik is met relatiewe lae energievereistes. Die voorgestelde beheer is suksesvol op 'n Land Rover Defender geïmplimenteer en 'n Proportioneele-Differensiaal (PD) beheerder word gebruik om die aan-af solenoїde kleppe te beheer terwyl die vloei aangepas word na gelang van die laterale versnelling. Eksperimentele resultate bevestig dat 'n beduidende verbetering in bakrol moontlik is.Dissertation (MEng)--University of Pretoria, 2012.Mechanical and Aeronautical Engineeringunrestricte

Volume 3 – Conference

We are pleased to present the conference proceedings for the 12th edition of the International Fluid Power Conference (IFK). The IFK is one of the world’s most significant scientific conferences on fluid power control technology and systems. It offers a common platform for the presentation and discussion of trends and innovations to manufacturers, users and scientists. The Chair of Fluid-Mechatronic Systems at the TU Dresden is organizing and hosting the IFK for the sixth time. Supporting hosts are the Fluid Power Association of the German Engineering Federation (VDMA), Dresdner Verein zur Förderung der Fluidtechnik e. V. (DVF) and GWT-TUD GmbH. The organization and the conference location alternates every two years between the Chair of Fluid-Mechatronic Systems in Dresden and the Institute for Fluid Power Drives and Systems in Aachen. The symposium on the first day is dedicated to presentations focused on methodology and fundamental research. The two following conference days offer a wide variety of application and technology orientated papers about the latest state of the art in fluid power. It is this combination that makes the IFK a unique and excellent forum for the exchange of academic research and industrial application experience. A simultaneously ongoing exhibition offers the possibility to get product information and to have individual talks with manufacturers. The theme of the 12th IFK is “Fluid Power – Future Technology”, covering topics that enable the development of 5G-ready, cost-efficient and demand-driven structures, as well as individual decentralized drives. Another topic is the real-time data exchange that allows the application of numerous predictive maintenance strategies, which will significantly increase the availability of fluid power systems and their elements and ensure their improved lifetime performance. We create an atmosphere for casual exchange by offering a vast frame and cultural program. This includes a get-together, a conference banquet, laboratory festivities and some physical activities such as jogging in Dresden’s old town.:Group 8: Pneumatics Group 9 | 11: Mobile applications Group 10: Special domains Group 12: Novel system architectures Group 13 | 15: Actuators & sensors Group 14: Safety & reliabilit

Relative ride vibration of off-road vehicles with front-, rear- and both axles torsio-elastic suspension

Wheeled off-road vehicles are known to transmit higher magnitudes of low frequency whole-body vibration (WBV), which have been associated with an array of health disorders among human drivers apart from fatigue and reduced work rate. In this study, the ride performance potentials of a torsio-elastic suspension employed in the front-, rear-, and both axles of an off-road vehicle are investigated. A three-dimensional ride dynamic model of the vehicle is formulated and analyzed under excitations arising from correlated random elevations of two terrain tracks. The model validity is demonstrated on the basis of reported field measured data of a rear-suspended frame-steered articulated forestry vehicle. The ride responses are evaluated in terms of unweighted and weighted root mean square (rms) accelerations along the translational and rotational axes near the driver seat. The results show that fully-suspended vehicle can yield substantial reductions in vibration along all the axes, and suspension in the axle in the proximity of driver cabin is relatively more effective in limited the WBV exposure. It is further shown that the linkage suspension helps preserve roll stability while providing adequate ride performance