Seat Surface Research Articles

Development of a seat support mechanism for guiding users to an appropriate posture in a seated-style echocardiography robot

Abstract This paper proposes a seat support mechanism to solve the problem of misalignment between the chest examination and probe scanning areas when the patient is bent in a seated-style echocardiography robot. To guide the patient to an appropriate body position where their chest is within the examination range of the chest examination unit while minimizing the physical load of the patient, the posture of the patient must satisfy the three following conditions. (i) The breech must be in contact with the seat surface, (ii) the legs must be vertical to the floor, and (iii) the chest and mechanism must be parallel while the probe scanning and chest examination ranges must match. The human body was modeled to derive a posture that satisfies the aforementioned conditions for the height of each individual, and a seat support mechanism with four degrees of freedom was installed to guide the user to the derived posture. By installing this mechanism, the body load of the left biceps brachii, right biceps brachii, left latissimus dorsi, and right latissimus dorsi was reduced to 64.7%, 52.7%, 86.4%, and 80.2%, respectively. The sharpness of the image contours was improved to 103.8%.

Padding the seat of a wheelchair reduces ischial pressure and improves sitting comfort.

In this study, we aimed to examine whether a wheelchair cushion placed directly atop a sling seat or deflection of the sling seat compensated by a pad along with the placement of a wheelchair cushion changed sitting pressure. Additionally, we examined whether these additions changed sitting comfort. For twenty healthy adults who consented to participate, measurements were taken for three types of cushions, each with and without padding, under six conditions. The cushion types tested included air (cushion A), urethane foam (cushion U), and three-dimensional thermoplastic elastomer (cushion T). A pressure distribution measurement equipment was used for the measurements. Following the measurement, the comfort of the wheelchair cushion was measured. The ischial area pressure of the cushion A pad was significantly lower than that without the pad. Cushions U and T were for ischial area pressure with a pad, resulting in a decreasing trend in ischial area pressure with a pad compared to that without a pad; however, the difference was insignificant. For all cushions, sitting comfort was significantly better in all groups with padding than in those without. In conclusion, ischial pressure can be dispersed by placing a pad on the seat surface of a wheelchair cushion, and pads were suggested to improve sitting comfort for all cushions.

A Local Heating Profile to Manage Lower Back Pain in an Automotive Seat: A Pilot Study.

Lower back pain (LBP) is one of the most prevalent health losses in adults worldwide. Historically, heat has been successfully used for treating pain and relieving tight muscles. Given the effective contact with the occupant's back and proximity to the heat source, coupled with increasing commute times, automotive seats offer an opportunity to intervene. Fifteen adults (nine female) who experienced acute, subacute, and chronic lower back pain were recruited to examine the effectiveness of heat delivered to the lower back in providing temporary pain relief. Participants sat in a car seat for 38 min on two days, which included a 5-min baseline followed by a 33-min intervention; control, or localized. For the control condition, participants sat for 33 min without any thermal devices on, while the localized condition heated and maintained the seat surface temperature of the lower seat back area to ~45 °C. Over the 33-min control condition, the back skin temperature increased by ~1-2 °C and did not impact the subjective LBP. Heating the lower back for 33 min to ~39 °C reduced the subjective LBP by 10%. We demonstrated that lower back pain can be alleviated from an automotive seat providing heat to the lower back within normal commute times in those with lower back pain.

Study of the Improvement of Disintegration Efficiency and Antibacterial Properties of Disposable Toilet Seat Cover Sheet Made of Cellulose Fibers

The growing prevalence of disposable toilet seat covers in public restrooms stems from concerns about personal hygiene, given the direct contact between the seat and various users’ skin. To enable these disposable cover sheets to be flushed down the toilet instead of being discarded in the trash, they must possess specific properties. These include rapid water absorption for quick disintegration, strength to endure user movement or moisture on the toilet seat surface, and a comfortable texture. To address these challenges, the study investigated the disintegration characteristics of flushable cover sheets prepared under different refining conditions. Alkyl ketene dimer (AKD) was also employed to enhance water resistance, while an organic antibacterial agent was used to impart antimicrobial properties. The findings revealed that adding 0.2% AKD and 1% organic antibacterial agent to pulp stock with a freeness of about 650 mL CSF was suitable for manufacturing disposable cover sheets with disintegration characteristics like toilet tissue paper.

EXPERIMENTAL INVESTIGATION INTO MAGNETORHEOLOGICAL FINISHING OF POLYMER VALVE SEAT SURFACE FOR BALL VALVE PERFORMANCE

A polymer valve seat is an essential component of ball valves. However, a gas pipeline valve leakage during the gas or oil transportation process causes major issues. Therefore, the fine finishing of the polymer valve seat is important. This work describes the effect of the magnetorheological finishing (MRF) process on the surface characteristics of the polymer valve seat. To achieve a finely finished polymer valve seat surface, the best process parametric combination of current, workpiece rotational, and tool rotational speed are obtained using the response surface methodology. The optimum process parameters are further used to enhance surface characteristics (including surface roughness, microhardness, and surface morphology) through fine finishing. Using the optimum process conditions, the surface roughness was reduced to 110[Formula: see text]nm from 570[Formula: see text]nm in 140[Formula: see text]min of finishing on a 4878[Formula: see text]mm2 surface area of the polymer valve seat. The circularity of the valve seat surface’s dimensional correctness is investigated further. The current MRF process can fine-finish the polymer valve seat surface consistently, resulting in improved surface characteristics and functional performance.

Study on Sustainable Lightweight Design of Airport Waiting Chair Frame Structure Based on ANSYS Workbench

The airport waiting chair frames, as an important part of the overall seating, must be designed to provide comfort, safety, and aesthetic appeal. While the airport furniture industry has made progress in terms of sustainability, more efforts are needed to improve material selection, manufacturing processes, and supply chain management to support the development of sustainable furniture. This study proposes innovative ideas for the lightweight design of the frame, based on the limitations of the existing design. Firstly, structural innovations are discussed, non-traditional mesh panels and curved rounded designs are discussed, and non-introduced mesh panels and curved designs are used to enhance the strength and stability of airport waiting chairs and enhance their overall performance. Secondly, innovations in lightweighting have focused on adjusting the thickness dimensions to enhance comfort, material utilization, and sustainability as well as to achieve a lightweight and thin appearance effect. In order to determine the optimal ranges of values for the thickness of the seat surface support strip (P5), the thickness of the backrest strip (P3), and the thickness of the seat panel (P1), nine groups of chairs with different frame sizes were tested using an orthogonal experimental method. Based on the experimental results for size and topology optimization, NX2312 software modeling will be imported into ANSYS Workbench for static analysis. Using the optimized results, the use of 2.842 kg of steel was successfully reduced by 34.8% to ensure the seat’s stability. This provides a reference and idea for the digital and standardized innovative design of airport waiting chair furniture structure in the future. Through digital design and lightweight optimization, material savings and effective use of resources can be achieved, promoting the goal of sustainable development.

Smart seat cushion feasibility pilot study: automated interface pressure modulation of individuals with spinal cord Injury

This study investigates the functionality and feasibility of a novel smart seat cushion system designed for wheelchair users with spinal cord injuries. The cushion, equipped with air cells that serve as both sensors and actuators, was tested on 24 participants for its real-time pressure mapping, automated pressure redistribution, and pressure offloading functions. A commercial pressure mat was concurrently used to validate the cushion’s pressure modulation functions. Additionally, the perceived comfort of the cushion was evaluated using General Discomfort Assessment (GDA) and Discomfort Intensity (DIS) scores, which provided insights into participants’ overall comfort and discomfort levels. Real-time pressure profiles generated by the cushion resembled commercial pressure mat readings. During tests with individuals with spinal cord injury, the cushion was able to dynamically generate and display the real-time pressure profile of a seated individual with strong precision (correlation to commercial pressure mat: r ranging from 0.76 to 0.88), providing effective input into pressure modulation functions. Pressure redistribution algorithms eliminated peak pressure and reduced the overall pressure at the interface. Pressure offloading algorithms automatically identified the regions with the highest interface pressure and subsequently relieved the pressure from those areas. User feedback showed that the cushion was comfortable after redistribution and offloading. This work demonstrated the feasibility of an advanced smart seat cushion system for wheelchair users with spinal cord injuries. The cushion was capable of redistributing pressure evenly across the seating surface, ensuring user’s comfort. Additionally, it identifies and eliminates high-pressure points, further improving comfort and reducing the risk of pressure injuries.

Development of aids to relieve vulvodynia during the postpartum period.

Postpartum women live with a low quality of life due to pain caused by episiotomy and perineal laceration. In particular, they endure pain when sitting for long periods of time to breastfeed. The purpose of this study is to develop a sitting aid to alleviate postpartum vulvodynia. This study was conducted in the following four phases from July 2017 to May 2019. They are: material selection and molding, cleaning and disinfection testing, pressure distribution measurement testing, and trial testing by postpartum women. The main material was a 100% polypropylene object with a three-dimensional reticular fiber spring structure and fiber density of 3.8 kg/m2. As a result, a sitting aid that withstands washing and disinfection well in the medical field and is breathable. It had moderate resilience and elasticity and reduced pressure on the seating surface for women weighing approximately 45 kg and 55 kg, but we were skeptical about its use for women weighing more than that. The completed sitting aid is noninvasively effective in improving the quality of life of many postpartum women, but the density and thickness of the main material should be reexamined to meet the needs of women in a wider weight range. In addition, a self-administered questionnaire survey of trial users revealed that some women did not experience relief from vulvodynia even after using the sitting aid. Such women also had physical problems such as discomfort in the lower back, difficulty breastfeeding, and difficulty standing up. For women with multiple physical problems, individual causes should be addressed.

Vibration reduction of human body biodynamic response in sitting posture under vibration environment by seat backrest support.

Four-degree-of-freedom (4-DOF) human-chair coupling models are constructed to characterize the different contact modes between the head, chest back, waist back and backrest. The seat-to-head transfer ratio (STHT) is used as an evaluation metric for vibration reduction effectiveness. The simulated vibration reduction ratio of the model is close to the experimental results, which proves the validity of the model. The peak STHT is obviously reduced (P < 0.05, T-test) with seat-backrest support. The experiments show that supporting the head ( , P < 0.05, Wilcoxon matched-pairs signed ranks) has the best vibration reduction effect (21%), supporting the chest back ( , P < 0.05) has a reduced effect (11%), and supporting the waist back ( , P < 0.05) has the weakest effect (4%). When the upper torso is in full contact with the backrest, the peak STHT curve and resonance frequency are positively correlated with the contact stiffness of the seat surface and negatively correlated with the contact damping. In order to reduce the seat-to-head transfer ratio, the lowest STHT peak and lowest total energy judgments were proposed as the selection methods for the selection of the contact stiffness and damping of the backrest in two environments (periodic and non-periodic excitation), respectively.

Residual Stresses and the Microstructure of Modeled Laser-Hardened Railway Axle Seats under Fatigue

Railway wheels are usually attached to axles by press-fitting; therefore, the mechanical processes taking place during operation can result in failure, with fatal consequences for the axle seats. This manuscript describes the effect of laser hardening on the residual stress state, microstructural parameters (lattice defects—dislocations, crystallites, microstrains, etc.), and mechanical properties of laser-hardened EA1N steel railway axles under fatigue life conditions. Differences were found between ground, single-track, and multi-track hardened surfaces. Tensile residual stresses, low dislocation densities and hardnesses, and different microstructures (tempered cubic martensite) were found at the overlapped tracks and at the boundary of the heat-affected zone and bulk surface compared with the hardened zone. As a result, the surface treatment of axle seats by laser hardening improved the fatigue failure resistance compared with untreated seats. Optimal properties of the integrity of the axle seat surface were achieved, including fatigue resistance, which seems to be positively influenced mainly by sufficient hardness and the appropriate microstructure. The influence of the other investigated parameters was not evident, and was reduced by the presence of fretting corrosion and press-fitting.

Research on Automotive Seat Heating Strategy Based on Objective Thermal Comfort Evaluation

Abstract Seat heating is an essential means to improve cabin occupant thermal comfort. How to set a reasonable seat heating strategy is very important to improve occupant thermal comfort and reduce vehicle energy consumption. Based on objective thermal comfort evaluation criteria, this paper analyzes three strategies: fixed heating power, fixed seat surface temperature, and intermittent seat heating. It explores the occupant thermal comfort characteristics under different strategies. It is found that the optimum heating power or optimum seat surface temperature to maintain occupant thermal comfort varies with the initial seat temperature. Compared with the two strategies of fixed heating power and fixed seat surface temperature, the intermittent seat heating proposed in this paper can make the human body reach the optimal state of comfort in a shorter period, and the power consumption is less as the seat heating is opened for a longer time. This intermittent seat heating strategy not only adapts to different low-temperature environments outside but also provides sufficient safety guarantees while improving human thermal comfort. It can provide some references for the design of car seat heating and research on passenger cabin thermal comfort.

Dynamic characteristics of a compliant seat coupled with the human body and a manikin during the exposure to the whole-body vibration: Effect of the polyurethane foam, the track position, and the measurement location

Purpose Transmissibility is used to assess dynamic responses of the occupant-seat system, and most studies have exclusively assessed the transmissibility from the floor to the cushion or the backrest surface with the human body. Methods In this investigation, the vertical vibration transmitted from the floor to six specific locations both on the seat surface and the frame when the seat was fixed on three positions on the track was examined utilizing an SAE J826 manikin and 12 male adults (0.25 to 20 Hz) for a duration of 120 seconds at three vibration amplitudes. Results The transmissibility from the floor to the headrest frame, the cushion surface, the headrest surface, the seat back frame, and the seat back surface all exhibited a principal peak frequency within 4-5 Hz. With the exception of the cushion frame, the principal peak frequency and the peak transmissibility in transmissibilities to all positions decreased with increasing vibration amplitude, indicating the non-linearity within the occupant-seat system. It was also found modifying seat track positions minimally affected the seat transmissibility to either the surface or the frame of the seat. Conclusions Polyurethane foam amplified vibration at peak frequency, simultaneously enhancing static sitting comfort and reducing the vertical vibration transmission above peak frequency.

The impact of accelerometer location and frequency weightings on the prediction of pleasantness ratings for vertical whole-body vibrations on an aircraft seat bench

Noise and vibration are two physical factors that can reduce the perceived comfort of passengers during a flight. In this application context, vibrations are often measured using accelerometers placed at the seat rail or with a seat pad between the seat surface and the buttock of a sitting person. To develop pleasant aircraft cabin environments, it necessary to know which measurement location best reflects subjective ratings and whether the application of a frequency weighting as proposed in the ISO 2631 standard is beneficial. In this study, 40 participants rated the pleasantness of sinusoidal whole-body vibrations in the vertical direction while seated on a typical aircraft seat bench and listening to a synthetic broadband aircraft cabin noise over headphones. The vibration signals covered seven frequencies and four vibration levels and ratings were made on a verbally anchored scale. The results showed that an increase in vibration level leads to more unpleasant ratings for each of the tested frequencies, independent of the accelerometer position. Although the ISO frequency weighting underpredicts the ratings for high frequencies in both cases, applying it to the seat rail measurements seems to reflect the pleasantness ratings better than the seat pad measurements proposed in the ISO 2631 standard.

Vehicle seat surface real-time control system with linear actuator to reduce vertical impact

For regular vehicles, the vibration generated when a vehicle passes through a groove or step is dampened but still remains and causes whole-body vibration (WBV) to occupants through vehicle seat. Several epidemiological studies have clearly demonstrated that prolonged exposure to vibration from vehicles is detrimental to human health and may cause motion sickness. To reduce this whole-body vibration. We designed a simple and effective feed-forward control system with compact actuator compatible to the limited under-seat dimension and power outlet of compact general passenger cars and successfully authenticated the possibility of vertical vibration reduction by controlling the vehicle seat surface vertical displacement. In this research, we designed a real-time feed-forward control system with transfer function model estimation. This real-time control system contains a commercial DSP device providing coherence input and output with a controllable delay. With the application of transfer function model and state space model, this system successfully estimated the upcoming vibration acceleration according to the input of the vibrational acceleration time-domain data acquired from lower arm when the test vehicle passing a step. Furthermore, it is possible to process the input data and control the linear actuator precisely to reduce the vertical impact observed as setting force reduction.

Pressure Distribution Comparison among Standard Seating Surfaces and Strap Seating System

AIMS: Pressure injuries (PIs) are common issues that can be minimized through the use of pressure-redistributing support surfaces. Cushions that provide immersion and contour are considered the most effective for pressure relief; however, others are readily available on the market. The aim of this study is to determine how a wheelchair equipped with Comfort Tension Seating&amp;reg;(CTS) compares to standard sling seating, foam, and a high-end pressure redistributing contoured cushion. &#x0D; &#x0D; MATERIALS &amp;amp; METHODS: Pressure redistribution qualities as measured through peak pressure index (PPI) using pressure mapping technology were gathered on four different seating surfaces -standard sling seat, CTS, and two cushion types flat cross-section foam, contoured-cushion, and CTS. Twenty non-disabled participants trialed each cushion for five minutes each. The methods of this study are described and outcomes analyzed by comparing the PPI and comfort of the four cushions.&#x0D; &#x0D; RESULTS: A Wilcoxon signed-rank test, and related samples Friedman&amp;rsquo;s two-way analysis of variance by ranks (ANOVA) was calculated. The results show that there is a significant difference between each of the cushions in comfort and pressure redistribution. There was a statistically significant difference in mean PPI between the three groups in which the CTS performed better than the sling and flat cross-section foam, but not quite as good as the high-end contoured cushion (p &amp;lt;.001). &#x0D; &#x0D; CONCLUSION: While not as optimal as the contoured M2 foam cushion, the CTS seating surface appears to provide superior pressure-redistributing performance compared to sling and flat cross-section foam. This suggests that the CTS could be used as a support surface for many applications, except for individuals with high-level PI risk, without using tilt and recline features.

VIBRO-ACOUSTIC ASSESSMENT OF GRAIN GRINDING MACHINE FOR HEALTH RISK FACTORS ANALYSIS

Grinding machines is one of the outcomes of the agricultural sector work process mechanization aimed at reducing tedium and drudgery on the workers and improving overall productivity and production. However, the machinery drive component and mechanical energy are associated with noise and vibration, thereby inducing safety and health concerns for the operators. This study assessed and compared the vibro-acoustic characteristics caused by three different types of grinding machines; electric motor (3HP220V2800HD), diesel (R175A) and petrol (GX160) power drive engines used in grinding shops located in Wadata, Makurdi Local Government Area of Benue State in association with the risk factors to the work environment. The instrumentation design for the grinding machine operations vibro-acoustic characterization was a sound level meter (S844+), a vibrometer (VM-6360), a digital stopwatch (PC-396) and retractable measuring tape (B300-AG). The noise measurements were made at an average seating height of 1.5 m in the operator’s work position and the vibrations on the seat surface of the operator. The data obtained were analysed for noise and vibration occupational risk exposure following the ISO 9612 for acoustics guidelines and ISO 2372 for mechanical vibration and shock. The average mean values for the noise level and vibrations were statistically highest when the diesel power drive engine, followed by the petrol engine, while the electric motor had the least vibro-acoustic effect. In addition, the analysis of the variance test showed that the result obtained for the vibration and noise levels for the three categories of power source drive had p-values less than 0.05, indicating that they are significantly different from zero at a confidence level of 95%. The findings of this study mandated that all operators of the machinery under investigation wear personal protective equipment (PPE).

Quantitative measurement and application of droplets on physical surfaces based on LIF technology

Abstract Contaminated surfaces play a significant role in the transmission of respiratory infectious diseases. To address this issue, we presented a novel quantitative detection method for droplets on physical surfaces, based on the laser-induced fluorescence technique. The proposed detection method was demonstrated in a realistic high-speed train compartment scenario by simulating the process of droplet release during passengers' breathing and coughing. The experimental results showed that this method could offer high precision (10−1 mg/m2) for detecting minute substance concentrations, and its ease of operation makes it suitable for complex engineering environments. The results also revealed that under the combined effects of the indoor airflow and breathing airflow, the range of droplets released by breathing activity exceeded two rows in front of and behind the release position. Simultaneously, we observed that a large number of droplets settled on the seat surfaces on both sides of the same row as the releaser, with over 36% of these droplets concentrated on the backrest area of the seats. As the respiratory jet velocity increased, the location with the most sediment droplets (accounting for 8% of the total sedimentation) occurred on the seat directly in front of the releaser, and approximately 48% of the droplets were found on the back of this seat. Our proposed method overcomes the shortcomings of existing experimental methods in quantitatively capturing the motion characteristics of droplets in complex flow fields.

Investigating water vapor retention of fabrics and their suitability for seat coverings

PurposeWater vapor trapped in the boundary layer between a person and the clothing creates discomfort and other unpleasant sensations. When that water vapor is prevented from leaving the clothing by external vapor barriers or impermeable layers, those psychophysical states are further exacerbated. One situation where that can be problematic is in office workplaces, and the seats that workers use for many hours every day. This study aims to evaluate the impact of different fabrics that are used for seat cover on water vapor retention.Design/methodology/approachThe authors' method determines the behavior of contact surface humidity with a 50 kg sandbag on the seat to mimic the deformation of the seat materials due to the seated person's weight. Thus, the maximum increase in relative humidity (RH) after humidification of the seat surface (ΔRH-max), the time required to reach the maximum value of humidity (t-max) and the time constant (TC) after humidity starts to fall were derived.FindingsOf the three different seat covers tested, the ΔRH-max of the wool were 7.3–8.8%, compared to 27.0–29.0% of the polyvinyl chloride (PVC), indicating more moisture absorption and transmission of the wool. The TC of the acrylic cover was 224–384 min compared to the 483–558 min of the PVC, which indicated a quick drying out feature of the acrylic.Originality/valueThe ΔRH-max, t-max and TC were all significantly correlated with the RH at the back thigh skin surface of the actual human participants.

Modified Egocentric Viewpoint for Softer Seated Experience in Virtual Reality.

Users in a prolonged experience of virtual reality adopt a sitting position according to their task, as they do in the real world. However, inconsistencies in the haptic feedback from a chair they sit on in the real world and that which is expected in the virtual world decrease the feeling of presence. We aimed to change the perceived haptic features of a chair by shifting the position and angle of the users' viewpoints in the virtual reality environment. The targeted features in this study were seat softness and backrest flexibility. To enhance the seat softness, we shifted the virtual viewpoint using an exponential formula soon after a user's bottom contacted the seat surface. The flexibility of the backrest was manipulated by moving the viewpoint, which followed the tilt of the virtual backrest. These shifts make users feel as if their body moves along with the viewpoint; as a result, they would perceive pseudo-softness or flexibility consistently with the body movement. Based on subjective evaluations, we confirmed that the participants perceived the seat as being softer and the backrest as being more flexible than the actual ones. These results demonstrated that only shifting the viewpoint could change the participants' perceptions of the haptic features of their seats, although significant changes created strong discomfort.

Effect of Whole-Body Vibration Exposure in Vehicles on Static Standing Balance after Riding

This study aims to investigate the effects of whole-body vibration (WBV) exposure on the disturbance of standing balance function assuming that the cause of slip, trip and fall accidents in the land transportation industry is related to WBV exposure when traveling in vehicles. In the experiment, ten participants underwent 60 min of virtual driving in a driving simulator (DS) for WBV exposure. In addition, standing balance measurements were conducted before exposure, immediately after exposure, 2 min after exposure and 4 min after exposure. Four conditions were considered by combining two magnitudes of WBV exposure and the driver and passenger conditions. This study focused on two indexes of standing balance, namely, total length and enveloped area and the rate of change relative to the value before the vibration exposure was calculated. The rate of change remained almost constant at 1.0 in the control condition without vibration exposure, whereas that under vibration exposure conditions varied. Interestingly, the rate of change at 2 min after exposure remained high in the driver condition, but it decreased to almost 1.0 in the passenger condition. Since no difference appeared in the vibration acceleration measured at the seating surface between the driver and passenger conditions, it was believed that the difference between the driving and passenger conditions was related to fatigue caused by the accelerator-pedal operation. As a result of considering the percentage of the standing balance that returned to 1.0 after 4 min in most conditions, this study proposed that a rest period of several minutes be allowed from the experiment in which the participants were exposed to vibration at 0.5m/s2 rms for 60 min at the DS. Further basic experiments will be conducted to introduce another WBV exposure assessment, including loss of standing balance as a health indicator, to ISO 2631-1.