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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]

The introduction of automated L5 driving technologies will revolutionise the design of vehicle interiors and seating configurations, improving occupant comfort and experience. It is foreseen that pre-crash emergency braking and swerving manoeuvres will affect occupant posture, which could lead to an interaction with a deploying airbag. This research addresses the urgent safety need of defining the occupant's kinematics envelope during that pre-crash phase, considering rotated seat arrangements and different seatbelt configurations. The research used two different sets of volunteer tests experiencing L5 vehicle manoeuvres, based in the first instance on 22 50th percentile fit males wearing a lap-belt (OM4IS), while the other dataset is based on 87 volunteers with a BMI range of 19 to 67 kg/m2 wearing a 3-point belt (UMTRI). Unique biomechanics kinematics corridors were then defined, as a function of belt configuration and vehicle manoeuvre, to calibrate an Active Human Model (AHM) using a multi-objective optimisation coupled with a Correlation and Analysis (CORA) rating. The research improved the AHM omnidirectional kinematics response over current state of the art in a generic lap-belted environment. The AHM was then tested in a rotated seating arrangement under extreme braking, highlighting that maximum lateral and frontal motions are comparable, independent of the belt system, while the asymmetry of the 3-point belt increased the occupant's motion towards the seatbelt buckle. It was observed that the frontal occupant kinematics decrease by 200 mm compared to a lap-belted configuration. This improved omnidirectional AHM is the first step towards designing safer future L5 vehicle interiors. [ABSTRACT FROM AUTHOR]

The automobile seat is an important and unique device in the automobile system, which directly contacts the human body. The dynamic characteristics of the automobile seat are the key parameters for its vibration security and dynamic performance. Both experiments and finite element simulations are conducted to analyse the fore-and-aft operating modes of a new type of automobile seat system in this paper. The results and their correlation analysis between the experimental data and the computational models are given. By using finite element simulations, the computational results of the modes with the first 12 orders for the automobile seat are in the range 0–100 Hz, including the integral modes and the local modes of the automobile seat. An experimental method was designed to measure the seat frame mode using an impact hammer, a triaxial accelerometer, uniaxial accelerometers and a 24-channel LMS vibration test system. The experimental data were analysed by estimating the frequency response function and the modal parameters and validated using LMS Test.Lab software. The experimental results for five integral modal parameters of the automobile seat between 0 Hz and 100 Hz are given. The orthogonal experimental method is used to design nine different working states of the automobile seat with variations in the positions of different adjustable devices (the headrest, the height adjuster, the recliner and the track slide). Finally, the influences of the above-mentioned adjustable devices on the fore-and-aft operating mode are analysed by the single-factor analysis method using finite element simulations. [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]

In this study, the tensile strength of laminated fabric used as an automotive seat cover was simulated using finite element analysis (FEA). The laminated fabric has three layers and is composed of plain weave fabric and twill 2/2 at different densities, polyurethane foam, and polyamide circular knitted scrim. FEA simulation was carried out on the constructed fabric geometrically using KTEX software. The laminated fabrics were then subjected to axial stress with opposing forces. The laminated fabric is assumed to be linear and elastic in FEA. The simulation outputs were compared with real test results and their graphs. The geometrical construction of laminated fabrics is crucial to obtain beneficial results. The tensile strength results of the simulations agree well with the actual values, although the strain–stress graphs may differ in several zones. The consistency between the actual test results and simulation may provide a model for surface deformation for further studies. [ABSTRACT FROM AUTHOR]

This paper presents the validation of a 50th-percentile male multi-body human model specifically developed for rear-impact simulation. The aim is to develop a biofidelic model with the simplest architecture that can simulate the interaction of the human body with the seat during rear impact. The model was validated using the head-and-neck and torso responses of seven volunteers from the Japanese Automobile Research Institute sled tests, which were performed at an impact speed of 8 km/h with a rigid seat and without head restraint and seat belt. The results indicate that the human-body model can effectively mimic the rear-impact response of a 50th-percentile male with a good level of accuracy and has the potential to predict whiplash injury. [ABSTRACT FROM AUTHOR]

Long duration exposure to vehicle induced vibration causes various ailments to humans. Amongst the various components of the human-vehicle system, the seat suspension plays a major role in determining the level of vibration transferred to humans. However, optimising the suspension for maximising human comfort leads to poor vehicle handling characteristics. Thus, predicting human comfort through various seat suspension models is a widely researched topic. However, the appropriate seat suspension model to be used has not been identified so far. Neither has any prior work reported integrating models of all the components necessary for this analysis, namely human body, cushion, seat suspension and vehicle chassis, each with the appropriate level of complexity. This work uses a two-dimensional 12 DoF seated human body model with inclined backrest support, a nonlinear cushion model, a seat suspension model and a full vehicle model. Two kinds of road profiles – one with random roughness and one with a bump – have been used. It then compares the performance of five different seat suspension models based on a number of human comfort related parameters (seat to head transmissibility, suspension travel, seat acceleration, cushion contact force and head acceleration in both vertical and fore-aft directions) and vehicle handling parameters (vertical, rolling and pitching acceleration of chassis). The results clearly show the superiority of the configuration which involves a spring parallel to an inclined multi-stage damper. A separate analysis was also done to judge whether the integration of the vehicle model (with its associated complication) was necessary for this analysis. A comparison of the human body's internal forces, moments, acceleration, and absorbed power with and without the vehicle model clearly indicates the need of using the former. [ABSTRACT FROM AUTHOR]

Considering the influence of mount structure parameters on the quality of vehicle noise, vibration and harshness (NVH), a multi-objective optimization method of the magneto-rheological (MR) mount based on vehicle vibration control was proposed. A lumped parameter model was used to establish the relationship between the structure parameters of the MR mount and the NVH performance of the vehicle. Considering the influence of current on the magneto-rheological fluid viscosity and flow rate in damping channel, the dynamic characteristics of MR mount was obtained by the lumped parameter model. Then, a 10 degrees of freedom (DOF) vehicle model with MR mounting system was established. Finally, a co-simulation optimal platform was developed by the ISIGHT, MATLAB, and ANSYS software, and the non-dominated sorting genetic algorithm II was used to optimize the design of the mount magnetic circuit with the goal of improving the quality of vehicle NVH. The results showed that under the start/stop and the constant speed conditions, the root mean square values of vibration acceleration of the driver's seat rail of the vehicle with the optimal design magneto-rheological mount decreases by 31.6% and 7.8%, respectively compared with the initial design mount, improved the ride comfort of the vehicle. [ABSTRACT FROM AUTHOR]

This research investigates the design, modeling, and control of an improved magnetorheological rotary damper for seat suspension. A magnetorheological damper with optimized flux path is developed to improve the distribution of magnetic field. Its dynamic damping characteristics are tested by MTS machine under sinusoidal excitations. To describe the nonlinear damping characteristics of magnetorheological damper, a hysteretic model based on backbone curve is selected by comparing with other models. To verify the feasibility of seat suspension with the proposed magnetorheological damper, the simulated analysis and experimental tests are conducted. A dynamic model of scissor seat suspension with rotary damper is constructed and simplified. The performances of semi-active system show that the seat suspension with the proposed damper can reduce vibration efficiently. [ABSTRACT FROM AUTHOR]

Back pain is a commonly known problem for drivers and passengers traveling in long route vehicles, especially buses and trucks. The problem becomes more severe for people suffering from bedsores. The current embodiment is a step toward addressing this problem. This method helps to regulate blood flow and provide comfort to the drivers and bedsore patients. Pneumatic cylinder and 24 semi-circular designed aluminum buds are used in the assembly that moves up and down along with the comforter foam and sheet to serve the purpose. This design is an active way of providing comfort and has significantly helped in reducing back and lower body pain. A survey was conducted by 100 participants to analyze the comfort of the current embodiment. The age of these participants was divided into two categories. Results showed that comfort varies with age and pressure. It was concluded from the survey that young people from 20 to 30 years appreciate high pressure, whereas elderly people from 30 to 50 years like low pressure. The results from analysis of variance were found to be significant with feedback results. This system is also helpful in regulating blood flow. It was concluded that most people like high pressure and the first pattern. [ABSTRACT FROM AUTHOR]

The complicated transfer path relationship between the vibrations of a seat and the noise at the locations of the driver’s ears was estimated from the residual spectrum. For accurate quantitative estimation of the rattle noise at the locations of the driver’s ears, in particular the partial coherence function of the pure inputs to the output was modelled by considering the correlation between the inputs and the input–output. Whenever a coherence analysis was performed with the noise sources in close proximity selected as the inputs and the noise at the locations of the driver’s ears modelled as the output, the partially coherent output spectrum as a quantitative contribution of the inputs to the output was determined. In this study, we applied a coherence analysis technique to identify the sources of the rattle noise of a seat by visualizing the noise sources with an acoustic camera while excitation of the seat was carried out using a hydraulic exciter. We were able to generate the rattle noise from the headrest stay, the recliner and the front part of the slide while excitation of the seat was obtained using a hydraulic exciter with white noise. We observed that the noise was generated by utilizing a hydraulic six-axis exciter positioned at the driver’s seat of a middle-sized manual transmission vehicle. We determined that the noise measured at the locations of the driver’s ears had a frequency of 58 Hz using acoustic visualization and a coherence technique. It was selected in particular as the target frequency since the 58 Hz resonant frequency caused by the twisting mode of the seat back was identical with the frequency of the rattle noise. Finally, it was verified through a modal test that the rattle noise at 58 Hz was generated by the vibration characteristics of the seat, which depended on gaps between the headrest stay and the guide. [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]