Browse Topic: Seats and seating
Realistic seat vibration reproduction is essential for delivering authentic haptic cues and enhancing driver immersion in driving simulators. Unlike direct playback of road recordings, simulator applications require vibration synthesis that responds interactively to driver inputs and vehicle dynamics. Reproducing these vibrations at the seat is often complicated by actuator bandwidth limitations and the dynamic behaviour of the seat structure itself, which can alter the intended target response. This work presents vibration synthesis and seat dynamics compensation strategies implemented on a single-axis seat vibration reproduction system equipped with a vertical actuator. Frequency Response Functions (FRFs) were measured to characterise the system dynamics under single-axis excitation. Run-up and coast-down tests were conducted on the seat and compared to target responses measured on an actual vehicle under operational conditions. Several seat dynamics compensation strategies were evaluated, including inverse FRF filtering, energy-based matching, and manual frequency-domain equalisation. The results indicate that single-input single-output (SISO) compensation approaches can achieve reasonable performance under independent single-axis excitation when compared to alternative methods. The study presents a comparative evaluation of these methodologies and highlights their respective challenges and limitations.
Dynamic responses at critical locations of a spacecraft due to excitations expected during the ascent phase of a launch vehicle mission are usually estimated through a Coupled Loads Analysis (CLA) using the structural dynamic finite element model of the launch vehicle coupled with that of the spacecraft. Generally, the full physical structural dynamic model of a spacecraft has lakhs of degrees-of-freedom (DOFs). Coupling such a model with a similar model for the launch vehicle results in exorbitantly high computational costs for CLA. Hence, dynamic analysis of such large and complex structural assemblies usually employ sub-structure coupling or Component Mode Synthesis (CMS) methods. The most widely used CMS method for dynamic analyses is the Craig-Bampton (CB) method. Conventionally, a full launch vehicle CLA involves one level of CB-reduction wherein a reduced-order dynamic model of the spacecraft is first generated using the fixed-interface CB-method. This reduced-order model is coupled with the launch vehicle model through the interface DOFs and CLA is performed using this coupled dynamic model. For test missions of ISRO’s manned space program, a simulated Crew Module (CM) is interfaced to the launch vehicle in place of the spacecraft. For CLA of this launch vehicle, a CB-reduced model of the CM is required. The CM comprises several sub-systems, including the Crew Seat Assembly (CSA), and dynamic responses at critical locations of these sub-systems need to be obtained from CLA. Structural dynamic model of the CSA is complex and involves lakhs of DOFs. Interfacing this detailed finite element model of CSA directly with the full model of CM for CB-reduction was found infeasible considering the prohibitively high computational time and resources required. An alternate approach is utilized to overcome the problem wherein the reduced-order dynamic model of CM is generated with two levels of nested sub-structuring. The CSA is represented as a CB-reduced model within the full physical structural dynamic model of CM, which is further CB-reduced and coupled with the launch-vehicle model for CLA. This paper presents the approach adopted to extract internal point dynamic responses on CSA from a dynamic analysis using the reduced-order dynamic model of CM with two-level CB-reduction. To validate the proposed approach, structural dynamic model of a skeletal structure of CM is generated encompassing the full model of CSA. A reduced-order dynamic model of this skeletal structure is also generated with two-level CB-reduction. A typical transient force excitation is considered and dynamic responses at internal points of CSA are estimated from the reduced-order dynamic model using the proposed approach. These responses are compared with corresponding responses obtained from a similar analysis with the full physical model of the skeletal structure and validity of the approach is established. The presented approach is generic and can be conveniently extended to extract responses from any dynamic analysis with models having even more than two levels of nested sub-structuring. Using this approach, the computational time and resource requirements for dynamic analysis studies are minimized. Dynamic analysis capabilities of MSC Nastran software are used for this study.
This paper presents an integrated simulation workflow for aircraft seat development that combines (i) structural dynamics and certification load cases, (ii) occupant comfort and living-space assessment using finite-element digital humans, and (iii) airbag folding, deployment, and calibration using a coupled gas-dynamics solver suited to early-time transients. The workflow is built around a single manufacturing-aware, as-built seat model that is reused across comfort, certification, and restraint-system studies, allowing design iterations to move upstream before design freeze. Each stage is paired with validation or industrial case examples, and the airbag-calibration process is accelerated through reduced-order modeling (ROM) of parameter identification. The result is a practical virtual-seat-development methodology that is sufficiently predictive to de-risk physical testing while remaining fast enough for concept iteration and late-stage compliance support.
This paper contains Part 2 of a two-part paper series proposing potential regulatory approaches for occupant safety in Automated / Autonomous Vehicles (AVs) with unique seating configurations (stagecoach and campfire seating). Part 2 focuses on interior safety sensing, associated messaging, and ride control approaches both prior to and during a ride. Assessments are also proposed after significant vehicle braking and crash events. The proposed conditions are to be assessed in a static vehicle environment with humans segmented by occupant size and an infant dummy. On the vehicle seat and on the vehicle floor occupant detection conditions are proposed along with restraint usage detection conditions for vehicle seat belt usage, Child Restraint Seat (CRS) usage, CRS seat belt usage, and Lower Anchors and Tethers for Children (LATCH) system usage. These conditions may be detected by sensors / computer algorithms and human monitoring and thus are technology agnostic. The topics of animal detection and cargo detection are also discussed. Part 1 of this paper series (SAE paper 2026-01-0578) proposed using interior safety sensing as an alternative / a replacement for the National Highway Traffic Safety Administration (NHTSA) Federal Motor Vehicle Safety Standard 208 (FMVSS-208) Occupant Crash Protection unbelted in-position occupant compliance conditions. This paper proposes conditions involving occupant and seat belt restraint usage detection. This evaluation approach strives to prevent unbelted occupants and is an improvement over restraint countermeasures for unbelted occupants. This paper also discusses and proposes visual and audible safety messaging for prior to the ride occupant education and for occupant and restraint usage detection outcomes. Vehicle level ride control actions are suggested such as preventing a ride when improperly restrained occupants are detected. These approaches can be used in industry-wide regulatory next step contemplation for unique interior seating arrangement AVs. When adopted, these approaches would likely reside in an expanded version of FMVSS-208.
Some Automated / Autonomous Vehicles (AVs) have unique seating configurations (stagecoach and campfire seating) which present expanded occupant safety challenges. Significant portions of the National Highway Traffic Safety Administration (NHTSA) Federal Motor Vehicle Safety Standards (FMVSS) do not yet align with AVs containing unique seating. This paper series takes the NHTSA occupant safety standard approach for conventional forward-facing seat vehicles where many compliance evaluations are in the frequently occupied front row and expands it to stagecoach and campfire AVs where the rear seating row is anticipated to be frequently occupied. The approaches proposed are from a logic-based safety-focused analysis and in many cases previously published material. The goal of this paper series is to offer regulatory proposals that enable equivalent performance for these AVs to existing forward-facing seating vehicle occupant safety standards and meet Executive Order 13045 on child safety. Part 1 (this paper) focuses on occupant protection for the front and rear seating rows in stagecoach and campfire seating AVs for: front impacts (FMVSS-208), windshield mounting (FMVSS-212), windshield glazing (FMVSS-219), rear impacts (FMVSS-301/305), head restraints (FMVSS-202a), head impacts (FMVSS-201), side impacts (FMVSS-214), roof crush (FMVSS-216a), ejection mitigation (FMVSS-226), and door pinch (a potential FMVSS-118 addition). Some of the proposals address occupant performance for vehicles without traditional leg and restraint reaction surfaces. In addition, an interior safety sensing approach that assesses if occupants are properly restrained before a ride can begin is proposed as an alternative / a replacement for unbelted in-position occupant performance compliance evaluations. This document also provides regulatory condition thoughts for AVs without a usable driver seat location. Part 2 (SAE paper 2026-01-0576) discusses interior safety sensing and associated messaging. These approaches can be used in industry-wide regulatory next step contemplation and deliberation for unique interior seating arrangement AVs, including public discussions, safety research, approach proposal development, and rulemaking efforts.
Lightweighting of components has become a key challenge in the development of modern transportation systems. In the automotive and aerospace industries, the overall mass of a vehicle has a significant impact on its fuel efficiency and manufacturing cost. Therefore, the lightweight design of vehicle components is crucial in the industrial field. Topology optimization (TO) is a computational design approach aimed at achieving lightweight designs. However, most existing studies focus on simplified academic models, with limited demonstration in real-world applications. This paper presents a revised TO workflow to obtain production-ready design and a practical implementation of TO in the design of three structural components in the aerospace industry: seatback frame, seat fuselage mount, and seat spreader. The revised TO workflow incorporates the practical demands of industry, including enhanced manufacturability and cost efficiency through TO design. The resulting designs are evaluated to ensure all regulatory requirements are satisfied. Comparative results show that the designs produced by the presented TO-based design method achieve a significant weight reduction of 50% for the seatback frame. For the seat fuselage mount and seat spreader, the proposed method produced designs with a weight comparable to the baseline while satisfying stricter crashworthiness requirements. These components also ensure manufacturability, efficient fabrication cost, and compatibility with family parts. These findings demonstrate that TO can deliver production-ready solutions without compromising structural performance. The study highlights the potential of integrating TO into a revised design workflow to support performance-driven development of complex, production-ready industrial components.
Rear-facing infant seats that are positioned behind front outboard vehicle seats are at risk of being compromised by the rearward yielding of occupied front seat seatbacks during rear-impact collisions. This movement can cause the plastic shell of the infant seat to collapse and deform, increasing the risk of head injuries to the infant. Current designs of rear-facing infant seats typically do not consider the loading effects from the front seatback during rear-impact situations, which results in weak and collapsible shell structures. Moreover, regulatory compliance tests, such as FMVSS 213, do not include assessments of rear-facing infant seats under realistic rear-impact conditions. as the bench used for the regulatory test lacks realistic vehicle interior components. This study emphasizes the need for revised testing methodologies that employ sled tests with realistic seatback intrusion conditions to facilitate the development of improved infant seat designs. Research shows that rear-facing infant seats designed for real-world loading conditions can improve safety and injury outcomes for infants in severe rear-impact collisions in the presence of front-occupied seats.
The automotive industry constantly strives to enhance vehicle safety, comfort, and customer satisfaction. One of the critical aspects influencing these factors is the mitigation of Buzz, Squeak, and Rattle (BSR) issues, which can significantly impact perceived vehicle quality and user experience. This paper focuses on the BSR challenges specifically encountered in bench seat latch & striker mechanisms. Vibrations and movement, especially during vehicle operation, exacerbate Buzz, Squeak & Rattle (BSR) problems, leading to acoustic disturbances that detract from the overall ride quality. Latch and striker in seat system is prone to squeaks and rattles (S&R) due to improper fitment, environmental conditions, or mechanical stress. These issues not only compromise the auditory experience but may also raise concerns about component durability and functionality. This paper outlines the root causes of BSR phenomena in these components, emphasizing the role of design optimization, material selection, and assembly precision in addressing these challenges. By addressing these concerns, automotive manufacturers can ensure a higher standard of quality, reinforcing customer trust and satisfaction in their products.
Combining simulation with probabilistic ML enables engineers to chart the full design landscape, quantify uncertainty and uncover viable options that intuition and brute force alone would miss. Components and systems are routinely designed and validated virtually through tools like CFD and FEA before any physical prototype is built. The benefits are obvious: faster iteration, reduced cost and better products. But simulation is not cheap. Each run can take hours, consume costly GPU/CPU resources and require highly skilled engineers who are already in short supply. Licenses and compute costs can easily reach tens of thousands of dollars per seat, and most teams can complete only a few runs per day.
Increasing digitalization of the aircraft cabin, driven by the need for improved operational efficiency and an enhanced passenger experience, has led to the development of data-driven services. In order to implement these services, information from different systems is often required, which leads to a multi-system architecture. When designing a network that interconnects these systems, it is important to consider the heterogeneous device and supplier landscape as well as variations in the network architecture resulting from airline customization or cabin upgrades. The novel ARINC 853 Cabin Secure Media-Independent Messaging (CSMIM) standard addresses this challenge by specifying a communication protocol that relies on a data model to encode provided and consumed information. This paper presents an approach to integrate CSMIM-specific communication concepts into a Model-Based Systems Engineering (MBSE) framework using the Systems Modeling Language (SysML). This enables a streamlined model-based method to design and implement aircraft cabin systems interconnected through a CSMIM-based communication network as well as to create airline-customized configurations. Based on the Cabin Data and Communication Modeling Language (CDACML), a SysML mean to link system interfaces with the CSMIM data model across multiple development levels is proposed. Multiple development levels as part of the left side of the widely-accepted V-model are supported to enable a model-based handover into the system level, for example, reducing the risk for interface inconsistencies. The link to the CSMIM data model is designed such that it can be used to extract system interface definitions for implementation activities through Model-to-Text (M2T) transformations. To show the validity of the approach, a smart aircraft seat occupancy detection use case is designed using the proposed approach as part of the activities of the left side of the V-model including the development of a prototype CSMIM communication module. The communication module is then deployed on networked hardware that is configured through a M2T transformation and which is technically realizing this use case.
This SAE Aerospace Standard (AS) defines minimum performance standards and related qualification criteria for add-on child restraint systems (CRS) which provide protection for small children in passenger seats of transport category airplanes. The AS is not intended to provide design criteria that could be met only by an aircraft-specific CRS. The goal of this standard is to achieve child-occupant protection by specifying a dynamic test method and evaluation criteria for the performance of CRS under emergency landing conditions.
Ride comfort is an important factor in the development of vehicles. Understanding the characteristics of seat components allows more accurate analysis of ride comfort. This study focuses on urethane foam, which is commonly used in vehicle seats. Soft materials such as urethane foam have both elastic and viscous properties that vary with frequency and temperature. Dynamic viscoelastic measurements are effective for investigating the vibrational characteristics of such materials. Although there have been many studies on the viscoelastic properties of urethane foam, no prior research has focused on dynamic viscoelastic measurements during compression to simulate the condition of a person sitting on a seat. In this study, dynamic viscoelastic measurements were performed on compressed urethane foam. Moreover, measurements were conducted at low temperatures, and a master curve using the Williams–Landel–Ferry (WLF) formula (temperature–frequency conversion law) was created.
Automotive seating systems have become increasingly sophisticated, providing consumers with more flexible configurations and comfort functionalities. Traditional power seating, which relied on a few motors to adjust the seat position, has evolved into more technically advanced reconfigurable systems equipped with additional feedback sensors and actuators. These advancements include features such as Easy Entry, Zero Gravity, Stadium Swivel, IP Nesting, Auto Lumbar/Bolster Adjustment and Power Long Rails. All the features indicate that the overall control of seating systems now resembles robotic arm control or multi-body control, involving numerous coordinated movements. In this paper, we propose a novel control strategy for the coordinated speed control of multiple motors. Unlike traditional seating controls, which typically use direct switches or open-loop systems, we introduce a feedback approach that incorporates Kalman-filter-based speed estimation using raw signals directly from Hall Effect sensors. The new proposed method enables the simultaneous coordination and synchronization of multiple motors, ensuring that the seat moves smoothly without colliding with other objects while providing a comfortable experience for the consumer. The design of the control system is discussed in detail, the simulation results and experimental data will be presented and analyzed in relation to the real system.
At present, electric head restraints have been developed locally, so overseas mechanisms are used. In this study, two concept mechanisms were developed, and in addition, one patent for a wing-out head restraint mechanism was additionally applied. The new mechanism has had an excellent effect on cost reduction and improvement of operating noise compared to the current one.
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