Skyhook surface sliding mode control on semi-active vehicle suspension systems for ride comfort enhancement

A skyhook surface sliding mode control method was proposed and applied to the control on the semi-active vehicle suspension system for its ride comfort enhancement. A two degree of freedom dynamic model of a vehicle semi-active suspension system was given, which focused on the passenger’s ride comfort perform-ance. A simulation with the given initial conditions has been devised in MATLAB/SIMULINK. The simula-tion results were showing that there was an enhanced level of ride comfort for the vehicle semi-active sus-pension system with the skyhook surface sliding mode controller

Semi-active suspension with semi-active inerter and semi-active damper

This paper investigates the application of semi-active inerter in semi-active suspension. A semi-active inerter is defined as an inerter whose inertance can be adjusted within a finite bandwidth by on-line control actions. A force-tracking approach to designing semi-active suspension with a semi-active inerter and a semi-active damper is proposed, where the target active control force derived by LQR control in the 'Reciprocal State-Space' (RSS) framework is tracked by controlling the semi-active damping coefficient and semi-active inertance. One of the advantages of the proposed method is that it is straightforward to use the acceleration information in the controller design. Simulation results demonstrate that the semi-active suspension with a semi-active inerter and a semi-active damper can track the target active control force much better than the conventional semi-active suspension (which only contains a semi-active damper) does. As a consequence, the overall performance in ride comfort, suspension deflection and road holding is improved, which effectively demonstrates the necessity and the benefit of introducing semi-active inerter in vehicle suspension.preprin

Evaluation of a semi-active gravity gradient system. Volume I - Technical summary

Semi-active gravity gradient system for attitude control of earth oriented spacecraf

Optimal control for semi-active suspension with inerter

The benefits of the inerter in passive suspension have been well demonstrated. To investigate suspension performances with the inerter in semi-active suspension, eight well studied passive suspension configurations with a parallel connection to a variable shock absorber are analyzed in this paper. By applying the optimal control theory, an optimal solution for each configuration is obtained and numerically solved by the forward/backward sweep method. The result shows that under the considered performance measure, the use of inerter can improve ride comfort in general, where the effect can even be significant for some specific configurations, but has no obvious advantage in road holding and suspension travel performance compared with the conventional semi-active suspension. © 2012 Chinese Assoc of Automati.published_or_final_versio

Robust vehicle suspension system by converting active and passive control of a vehicle to semi-active control ystem analytically

This research article deals with a simplified translational model of an automotive suspension system which is constructed by considering the translation motion of one wheel of a car. Passive Vehicle Suspension System is converted into Semi Active Vehicle System. Major advantage achieved by this system is that it adjusts the damping of the suspension system without the application of any actuator by using MATLAB® simulations. The semi-active control is found to control the vibration of suspension system very well

Improving the vibration suppression capabilities of a magneto-rheological damper using hybrid active and semi-active control

This paper presents a new hybrid active & semi-active control method for vibration suppression in flexible structures. The method uses a combination of a semi-active device and an active control actuator situated elsewhere in the structure to suppress vibrations. The key novelty is to use the hybrid controller to enable the magneto-rheological damper to achieve a performance as close to a fully active device as possible. This is achieved by ensuring that the active actuator can assist the magneto-rheological damper in the regions where energy is required. In addition, the hybrid active & semi-active controller is designed to minimize the switching of the semi-active controller. The control framework used is the immersion and invariance control technique in combination with sliding mode control. A two degree-of-freedom system with lightly damped resonances is used as an example system. Both numerical and experimental results are generated for this system, and then compared as part of a validation study. The experimental system uses hardware-in-the-loop to simulate the effect of both the degrees-of-freedom. The results show that the concept is viable both numerically and experimentally, and improved vibration suppression results can be obtained for the magneto-rheological damper that approach the performance of an active device

Semi-Active Control of Dynamically Excited Structures Using Active Interaction Control

This thesis presents a family of semi-active control algorithms termed Active Interaction Control (AIC) used for response control of dynamically excited structures. The AIC approach has been developed as a semiactive means of protecting building structures against large earthquakes. The AIC algorithms include the Active Interface Damping (AID), Optimal Connection Strategy (OCS), and newly developed Tuned Interaction Damping (TID) algorithms. All of the AIC algorithms are founded upon the same basic instantaneous optimal control strategy that involves minimization of an energybased performance index at every time instant. A typical AIC system consists of a primary structure targeted for vibration control, a number of auxiliary structures, and interaction elements that connect the auxiliary structures to the primary structure. Through actively modulating the operating states of the interaction elements according to pre-specified control logic, control forces favorable to the control strategy are reactively developed within the interaction elements and the vibration of the primary structure is thus restrained. The merits of this structural control approach include both high control performance and minimal external power requirement for the operation of the control devices. The latter is important during large earthquakes when power blackouts are likely to occur. Most encouraging is that with currently available technology this control approach can be readily implemented in real structures. In this thesis, the cause for an overattachment problem in the original OCS system is clarified and corresponding counter-measures are proposed. The OCS algorithm is reformulated within an energy framework and therefore all of the AIC control algorithms are unified under the same instantaneous optimal control strategy. To implement the AIC algorithms into multi-degree-of-freedom systems, two approaches are formulated in this thesis: the Modal Control and Nodal Control approaches. The Modal Control approach directs the control effort to certain dominant response modes, and the Nodal Control approach directly controls the response quantities in physical space. It is found that the Modal Control approach is more efficient than the Nodal Control approach. The effectiveness of the AIC control algorithms is verified through numerical simulation results for three-story, nine-story and twenty-story steel-framed buildings. The statistical behavior of the AIC system is evaluated based on a Monte Carlo simulation

Vibration isolation with smart fluid dampers: a benchmarking study

The non-linear behaviour of electrorheological (ER) and magnetorheological (MR) dampers makes it difficult to design effective control strategies, and as a consequence a wide range of control systems have been proposed in the literature. These previous studies have not always compared the performance to equivalent passive systems, alternative control designs, or idealised active systems. As a result it is often impossible to compare the performance of different smart damper control strategies. This article provides some insight into the relative performance of two MR damper control strategies: on/off control and feedback linearisation. The performance of both strategies is benchmarked against ideal passive, semi-active and fully active damping. The study relies upon a previously developed model of an MR damper, which in this work is validated experimentally under closed-loop conditions with a broadband mechanical excitation. Two vibration isolation case studies are investigated: a single-degree-of-freedom mass-isolator, and a two-degree-of-freedom system that represents a vehicle suspension system. In both cases, a variety of broadband mechanical excitations are used and the results analysed in the frequency domain. It is shown that although on/off control is more straightforward to implement, its performance is worse than the feedback linearisation strategy, and can be extremely sensitive to the excitation conditions