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This paper presents a novel, simple and reliable control strategy for an active seat suspension, intended for use in a vehicle, which attenuates the harmful low-frequency vertical vibration at the driver’s seat. An advantage of this strategy is that it uses measurable preview information from the vehicle suspension. The control force is calculated from this preview information and controller gains obtained by optimising an objective function using a genetic algorithm (GA) approach. The objective function optimises ride comfort in terms of the Seat Effective Amplitude Transmissibility factor, taking into account constraints on both the allowable seat suspension stroke and actuator force capacity. This new controller is evaluated using both simulation and experimental tests in both the frequency and time domains. The simulation model is based upon a linear quarter vehicle model and a single degree of freedom seat suspension. Experimental tests are performed using a multi-axis simulation table and an active seat suspension. Finally, the performance of the active seat suspension is analysed and compared to a passive system, demonstrating significant acceleration attenuation of more than 10 dB across a broad frequency range. Consequently, this has the potential to improve ride comfort and hence reduce the driver’s fatigue using a reliable and cost-effective control method. [ABSTRACT FROM AUTHOR]

This paper presents a new hybrid controller which is a combination of three control schemes: fuzzy neural control, PI control and sliding mode control. The interval type 2 fuzzy model featuring updated rules via online is used in this study and in order to support the fuzzy model, a granular clustering method is applied to find groups of data related to the initial fuzzy rule. Then the output for fuzzy model is used for the PI-sliding mode controller. The combination of PI and sliding mode controls is carried out by H-infinity technique method which is rely on the modified Riccati-like equation. After developing the mathematical model, the proposed controller is applied to vibration control of a vehicle seat suspension featuring magneto-rheological (MR) damper. In order to demonstrate the effectiveness of the proposed controller, two different excitations of bump and random signals are adopted and corresponding vibration control performances are evaluated. It is demonstrated through both simulation and experiment that the proposed controller can provide much better than vibration control performance compared with the conventional controllers showing more robust stability. [ABSTRACT FROM AUTHOR]

This paper is concerned with the problem of robust H∞ reliable load-dependent control design for a class of semi-active seat suspension systems. A four degree-of-freedom human body model is considered in order to investigate the control strategy more precisely. It is assumed that the human body mass resides in an interval and can be measured online. The load-dependent approach is based on a parameter-dependent Lyapunov function. Thus the proposed method is capable of reducing the conservatism and improving the closed-loop performance. Actuator faults are also considered in the controller design process and the resulting control systems are reliable because they provide guaranteed asymptotic stability and H∞ performance in spite of the possible actuator failures. The usefulness and advantages of the controller design methodology are demonstrated through a design example. [ABSTRACT FROM PUBLISHER]

Ford Motor Company has developed a corporate engineering test procedure focused on the vibration transmissibility of the occupied automotive seat. The procedure allows Ford to assess, in a consistent manner, the performance of (1) prototype-level seats specific to new/future programs and (2) production-level competitive seats. As part of the procedure, a complete seat system is mounted to a human-rated platform using a dedicated fixture, engaged by persons matching specific anthropometric characteristics, and excited vertically, laterally, and fore-aft with external actuators under laboratory conditions. Johnson Controls is one of the few seat suppliers that have the equipment and expertise required to execute this procedure. Using Ford's procedure, the objective of this paper is to compare and contrast the test results, expressed both statistically and graphically as transfer functions, produced by these two independent facilities. Because of the proximity of the two laboratories, it was possible to use the same production level seat and the same occupants at both facilities. The results showed good agreement in all excitation directions. Based on the strength of these results, discussions concerning specific noise, vibration and harshness (NVH) and ride quality requirements, which Ford cascades to Johnson Controls on a program-by-program level, can begin from a common basis. The common understanding, while yielding a more efficient seat development process, should lead to more comfortable vehicles. [ABSTRACT FROM AUTHOR]

Discusses the application of state space modeling for the control of an industrial seat test rig. Use of the system in the automotive industry to test prototypes of new seats with respect to comfort and vibration characteristics; Description of the Time Waveform Replication process (TWR); TWR method based on a state space modeling technique and the Stable Dynamic Inversion procedure.

Seated occupants of any on/off-road vehicle are continuously exposed to undue low-frequency mechanical whole-body vibration (WBV) owing to the vibration conveyed from seat and backrest because occupants need to compromise with comfort and safety, leading to several musculoskeletal disorders and injuries in the body. Pain in the lumbar region is one of the most common problems that develop because of force transmitted from the backrest. Thus, consideration of backrest is highly essential while developing a biomechanical model for ride comfort analysis. For this purpose, a 20 degrees-of-freedom (dofs) biomechanical model has been proposed with a backrest to analyse cross-coupled segmental transmissibility. The interconnection between different segments of mass and backrest are modelled using eight linearized (direct as well as cross-coupled) stiffness and damping parameters. Biomechanical model parameters are estimated and optimized through a multi-objective firefly algorithm by minimizing the sum of squares error difference between analytical results and experimental segmental transmissibility published in the literature. Subsequently, ride comfort analysis is performed by integrating the proposed model with 7- dofs passenger car model. For different body segments, simulated results are obtained in terms of vertical accelerations and compared with ride comfort standards as per ISO 2631-1:1997. Additionally, a sensitivity analysis (±20% variation in mass, stiffness and damping) is performed to enhance the ride comfort of the occupant. The findings suggest that designers must focus on the pelvis, lower and upper back regions to improve the ride comfort of the occupants. The concepts and ideas outlined in this article are directly applicable in making human dummies, car suspension and seat design in the industry. [ABSTRACT FROM AUTHOR]

Experimental techniques and identification of dynamic properties of flexible polyurethane foam used in automotive seats are described here. In the experimental fixture a rigid block is mounted on a 3 inch cube of foam material, which serves as the only flexible component. The dynamic system is modeled as a single degree-of -freedom system. The experimental fixture is excited by a small impulse at the top of the block and by a shaker on the basement. For the first situation the foam is simplified as a linear viscoelastic material. By exciting with the shaker the nonlinear and viscoelastic properties of foam materials are considered. For these two different cases not only the model response and the impact of model parameters are analyzed but also the corresponding system parameters are identified during the experimental data. [ABSTRACT FROM PUBLISHER]