Adaptive Seat Research Articles

Development of a Novel Magneto-Rheological Elastomer-Based Semi-Active Seat Suspension System

Human operators in the transportation sector are exposed to whole-body vibration (WBV) while driving. Occupational exposure to WBV, predominant at low frequencies (<20 Hz), has been linked to spinal injuries and reduced functioning. This study aims at the design development of a novel semi-active seat suspension system featuring magneto-rheological elastomers (MREs) to mitigate the WBV. The proposed suspension system allows a greater range of strokes, while ensuring the MRE remains within an acceptable level of deformation. Several MRE samples were fabricated and characterized under shear mode. Afterward, a field- and frequency-dependent phenomenological model was developed to predict the viscoelastic properties of MREs as functions of both the excitation frequency and applied magnetic field. The MRE material model was subsequently used to design and optimize an adaptive seat suspension system incorporating a C-shaped MRE-based isolator in parallel and series with passive springs. The proposed adaptive seat suspension system demonstrated a frequency shift of 29% by increasing the applied current from 0 to 2 A. Finally, a 6-DOF lumped parameter model of a seated human subject combined with the proposed semi-active suspension system featuring the MRE isolator has been formulated to investigate the vibration transmissibility from the floor to the subject’s head.

Influence of biomechanical compliance on control performance of a magnetorheological sliding seat system

We investigate the feasibility of a sliding seat with a magnetorheological (MR) energy absorber (MREA) to minimize loads transmitted to a payload in a ground vehicle for frontal impact speeds ranging as high as 7 m/s (15.7 mph). The crash pulse for a given impact speed was assumed to be a rectangular deceleration pulse having a prescribed magnitude and duration. The control objective is to bring the seat system to rest using the available stroke, while accommodating changes in impact velocity and occupant mass ranging from a 5th percentile female to a 95th percentile male. The seat system was first treated as a single-degree-of-freedom (SDOF) rigid occupant (RO) model, and two control algorithms are developed: (1) constant Bingham number control and (2) constant force control. To explore the effects of occupant compliance on the adaptive seat system performance, a multi-degree-of-freedom (MDOF) compliant occupant (CO) model was integrated with the seat mass and the same control algorithms were used. Simulation results showed that the designed adaptive controllers successfully controlled load-stroke profiles to bring the seat system to rest in the available stroke and reduced occupant decelerations. Analysis showed extensive coupling between the seat structures and occupant biodynamic response.

Adaptive Seat Cover for Motorsports and Daily Driving Situations

Adaptive Seat Cover for Motorsports and Daily Driving Situations

Reducing Lumbar Spine Vertebra Fracture Risk With an Adaptive Seat Track Load Limiter

In future fully automated vehicles, sleeping or resting will be desirable during a drive. While a horizontal position currently appears infeasible, a relaxed seating position with a reclined seatback and an inclined seat pan which enables a safe, comfortable position for sleeping or resting is possible. However, the inclined seat pan increases the forces and moments acting on the lumbar spine of the occupant and thereby the risk of lumbar vertebra fractures in a frontal crash. An energy management system integrated into the longitudinal seat adjustment (a seat track load limiter: STLL) that can reduce this risk should be investigated. When evaluating the injury reduction potential of a new restraint system such as a STLL it is important to include variations in both occupant size and crash severity. Otherwise, there is a risk of sub-optimizing, that is, the restraint system is only working for a limited number of situations. The restraint systems addressing these variations are normally referred to as adaptive restraint systems. The first objective of the study is to develop an activation strategy (adaptive release time of the STLL) for different crash severities and occupant sizes, making full use of the available stroke distance without bottoming out the STLL. The second objective is to evaluate the potential of the adaptive STLL to reduce the risk of lumbar vertebra fractures by comparing it to 1) a fixed seat and 2) a passive version of the STLL. Simulated frontal impacts were performed with two male SAFER human body models (HBMs) as occupant surrogates: mid-sized (80 kg and 1.8 m) and large (130 kg and 1.9 m). Three crash pulse severity levels were evaluated: low (40 km/h), medium (50 km/h), and high (56 km/h) impact speeds. The fracture risk was evaluated for the five lumbar vertebrae (L1–L5) in three different seat conditions: 1) a seat fixed to the sled, 2) a passive STLL that moves when a given force is exceeded, and 3) an adaptive STLL which moves at a time that depends on the occupant mass and crash pulse severity. The risk for lumbar vertebra fracture increased with crash pulse severity, while HBM size had no effect on risk. For all conditions, the passive STLL reduced injury risks compared to the fixed seat, and the adaptive STLL reduced risk even further.

Adaptive Automobile Seat Design Based on Ergonomic Principle

In order to improve the comfort of automobile seat, it is necessary to analyse and study the design method of automobile seat. A design method of adaptive automobile seat based on ergonomics principle is proposed. The height, width, depth, backrest, seat inclination and backrest inclination of automobile seat as well as the sitting posture physiology and body pressure distribution of human body are analysed. The frame of automobile seat is designed by using aluminium alloy in PROE software, the size of the energy absorption of headrest, cushion and seat are determined according to national regulations. By analyzing the back force, pillow force, seat belt force and seat belt locking, the force of automobile seat, the strength of back, head pillow and seat cushion of automobile seat are designed and the design of adaptive automobile seat is completed. The experimental results show that the proposed method has high comfort, low processing cost and high production efficiency.

System Level Crash Sled Simulations forEvaluating Helicopter Adaptive Seat Damper

This research study focuses on the finite-element based nonlinear dynamic model development and analysis for virtual evaluation of adaptive seat dampers for enhanced occupant protection during vertical crash landings of a helicopter. The current state-of-the-art helicopter crew seat has passive safety mechanisms that are highly limited in their capability to optimally adapt to each type of crash scenario due to variations in both occupant weight and crash severity level. While passive crash energy absorbers work well for a single design condition (50th percentile male occupant and fixed crash severity level), they do not offer adequate protection across a broad spectrum of crash conditions by minimizing the load transmitted to the occupant. This study reports the development of a finite-element based seat-occupant system level model using LS-DYNA3D for rotorcraft crash injury simulation. This finite element simulation model of a seated occupant with five-point belt and stroking seat is used to study occupant kinematics and spinal injury assessments to support crash sled evaluations of seat energy absorbers. The injury criteria and tolerance levels for the biomechanical effects are discussed for each of the adult-sized occupants with respect to thoracic lumbar loads. The desired objective of this analytical model development is to develop an analysis tool to study the performance effectiveness of adaptive seat energy absorbers for enhancing rotorcraft occupant crash protection

Influence of Occupant Compliance on a Vertically Stroking Helicopter Crew Seat Suspension

This study addresses the effects of compliance of an occupant seated in an adaptive seat suspension equipped with a magnetorheological energy absorber, and exposed to intense vertical shocks. A 50th percentile male occupant, exposed to shock conditions characterized by sink rates varying from 5 to , was considered. The compliance effects were examined by comparing the response of a multiple degree-of-freedom biodynamic lumped-parameter model derived from the response of a Hybrid II anthropomorphic test dummy representing a compliant-occupant model to the response of an equivalent rigid-occupant model under the same shock conditions. An experimentally validated nonlinear mathematical model of a magnetorheological energy absorber was integrated with both the compliant and rigid models of the occupants. In addition, three different control techniques were investigated based on controlling the onset of magnetorheological-energy-absorber stroking load: constant stroking-load control, terminal trajectory control, and optimal control. The internal damping of a compliant occupant proved to be a crucial parameter in determining the biodynamic response for all control techniques. An assessment of the potential of injury was conducted based on the established injury criteria for compliant occupants to evaluate the applicability of the control techniques.

ADSEAT – Adaptive seat to reduce neck injuries for female and male occupants

Neck injuries sustained in low severity vehicle crashes are of worldwide concern and the risk is higher for females than for males. The objective of the study was to provide guidance on how to evaluate protective performance of vehicle seat designs aiming to reduce the incidence of neck injuries for female and male occupants. The objective was achieved by reviewing injury risk, establishing anthropometric data of an average female, performing dynamic volunteer tests comprising females and males, and developing a finite element model, EvaRID, of an average female. With respect to injury criteria, it was concluded based on the tests that using NIC (with a lower threshold value) and Nkm (with reduced intercept values) for females would be a suitable starting point. Virtual impact simulations with seats showed that differences were found in the response of the BioRID II and EvaRID models, for certain seats.

ADSEAT - Adaptive Seat to Reduce Neck Injuries for Female and Male Occupants

Neck injuries due to low severity vehicle crashes are of worldwide concern and the risk is higher for females than for males. The objective of ADSEAT is to provide guidance on how to evaluate the protective performance of vehicle seat designs aiming to reduce the incidence of neck injuries for female and male occupants. The main achievements are: reviewing injury risk, establishing anthropometric data of an average female, performing dynamic volunteer tests comprising females and males, developing a finite element model of an average female and performing sled tests with a scaled down male dummy.

Development of Adaptive Seat Mounts for Helicopter Aircrew Body Vibration Reduction

Helicopter aircrew are exposed to high levels of vibration and noise during flight. This paper presents the investigation of adaptive seat mount approaches to reducing vibration on the helicopter seat. A flight test on a helicopter with typical pilot configurations showed that the vibration spectra on the pilot’s helmet not only included the dominant N/rev harmonic peaks of the rotor speed, but also consisted of a low-frequency resonant peak in the frequency range of human abdominal and spine resonant frequencies. Long-term exposure to this vibration may lead to occupational health issues such as damage to the pilot’s spine and neck. In order to address this issue, a novel adaptive seat mount concept was developed to mitigate the vibration levels transmitted to the aircrew. As a proof-of-concept demonstration, a miniature modal shaker was installed between the cabin floor and the seat bottom as an adaptive mount that provided the actuation authority. The objective was to reduce the vertical vibration transmitted to the aircrew helmet in order to decrease aircrew neck and spine injuries that are caused by the transmitted vibration. Extensive closed-loop control tests have been conducted on a full-scale helicopter seat and a mannequin with varying physical properties. A 10,000 lb(f) mechanical shaker was used to provide representative helicopter vibration profiles to the seat. Significant vibration reductions on the N/rev vibration peaks were achieved1 the low-frequency resonant peak was also suppressed simultaneously.

DEVELOPMENT OF SMART STRUCTURE SYSTEMS FOR HELICOPTER VIBRATION AND NOISE CONTROL

Helicopters are susceptible to high vibratory loads, excessive noise levels and poor flight stability compared to fixed-wing aircraft. The multidisciplinary nature of helicopter structures offers many opportunities for the innovative smart structure technology to improve helicopter performance. This paper provides a review of smart structures research at the National Research Council Canada for helicopter vibration and cabin noise control applications. The patented Smart Spring approach is developed to vary the blade impedance properties adaptively to reduce the vibratory hub loads transmitted to the fuselage by vibration reduction at the source. A smart gearbox strut and active structural acoustic control technologies are investigated to suppress the vibration and tonal gear meshing noise into the cabin either by modifying the vibration load transmission path, or weakening the coupling between exterior and cabin acoustic fields. Two adaptive seat mount concepts are proposed to reduce the vibration of the aircrew directly to improve ride quality of the vehicle.

An adaptive method for generating demand inputs to airline seat inventory control models

In order to increase the passenger load factor and total profit, most airlines offer several different fares to passengers on the same flight. Seat inventory control is the process of assigning the available number of seats to different fare classes. During the last three decades, various aspects of this problem have been considered in the literature. The basic input data for the existing airline seat inventory models are the demand distributions for seats in particular fare classes. Statistical data as a base for forecasting future passenger demand are very often not available (opening a new route, significant changes in fares, the appearance of competitive carriers, etc.). The current models are not able to handle cases where no prior historical data is available. This paper attempts to develop an approach to deal with this problem. The adaptive airline seat inventory control, which is proposed, is based on the Bayesian approach. The model developed is illustrated by numerical examples.

Early use of adaptable seating for patients with head trauma. Suggestion from the field.

The indivdiual who has suffered a severe head injury and is recovering from coma has unique problems in his ability to sit. These patients often lack head and trunk control and have abnormal muscle tone that further complicates any attempts at seating them. Initially, these patients require a maximum amount of head, trunk and pelvic support; as recovery progresses, external support can be reduced. Recovery of motor control in the head-injured patient will often occur at a relatively rapid rate. Changes in the amount of support may need to be made on a daily basis. Thus, manufacture of a permanent adaptive seat in the early stages of recovery is neither practical nor cost-efficient. The staff of the Brain Injury Program at Elizabethtown Hospital has developed a temporary, reusable adaptive seat insert, which is individually fitted and has the capability for adjustable external supports.