Use Of Pressure Sensors Research Articles

State estimation of a novel brake-by-wire system based on cascade observer

Pressure regulation is the primary function of the brake-by-wire (BBW) system, and its prerequisite is the precise pressure acquisition. In autonomous vehicles(AVs), a higher fail-safe level is required that a backup pressure source is available when the main pressure source fails. So the use of pressure sensors, like the existing method, for pressure regulation will increase the cost of BBW systems in AVs. To meet the requirement of brake redundancy and the cost limit, a novel BBW system with a redundant pressure supply unit is designed and its electro-mechanical-hydraulic model is analyzed in this research. A time-domain observer (TDO) of motor speed is designed based on the periodic characteristics of motor current to get more system information. Next, the robust observer of pressure is proposed based on the existing current sensor and the derived motor speed. Its computational burden is reduced by calculating the matrices offline. The estimator developed in this paper is verified in typical pressure regulation conditions. Experimental results show that the estimation error of the motor speed is within 3% and has the potential to be improved, and the error of pressure is within 0.1 MPa, and the observer exhibits enough robustness under different initial condition perturbations.

On the mixed acoustic and vibration sensors for the cross-correlation analysis of pipe leakage signals

Pipe leak detection can be carried out by various acoustic/vibration sensors, such as acoustic pressure, velocity and acceleration sensors. The purpose of this study is to investigate the effectiveness of the mixed acoustic/vibration sensors for the determination of pipe leakage. Firstly, a propagation and attenuation model of leakage signal in the liquid-filled pipeline is established based on frequency response functions. Further, the expressions of the cross-correlation function of different sensor types are derived with respect to the differential properties of Fourier transform. Then, the influence of signal-to-noise ratio (SNR) on the cross-correlation function is analyzed. Numerical simulation is employed to generate pressure, velocity and acceleration signals by differentiating the leakage source signals. Simulation results indicate that the use of pressure sensor acts as low-pass filtering operation, whereas the velocity and acceleration sensors act as band-pass filtering. Finally, experimental work is carried out on a medium density polyethylene (MDPE) pipe. Leakage signals are collected synchronously by hydrophones and accelerometers. Experimental results show that the cross-correlation function of hydrophones fluctuates slowly with peak value being less obvious, while the cross-correlation function of accelerometers fluctuates rapidly and has a sharper peak. In comparison, there is a compromise in the fluctuation for the sake of peak sharpness in the cross-correlation function of the mixed sensors, indicating that the corresponding cross-correlation result are less affected by background noise.

Adaptation and application of the Algorithm for Inventive Problem Solving in the design of the automatic control system for pumping water station

The growing demand of visitors to hotels oriented to the ecological and cultural tourism approach represents a challenge for the optimization of water resources, in contrast to traditional hotels, these depend exclusively on water wells. This type of commercial establishment is growing in Latin American countries such as Mexico, El Salvador, Ecuador, as well as in European countries such as Spain. The solution to this problem is of great importance for this type of tourist establishments. The environmental and economic spheres are the most affected due to this problem. This is due to the waste of water and excessive payment for electricity. There are many advantages related to the automation of the pumping system: the ability to save fuel resources, reduce machine wear for maintenance and repair time. This cost and time savings will increase the profits of the hotels, while the workload of the maintenance Department is reduced because the constant monitoring of the water level in the tanks would not be necessary. This article focuses on the specific case of a hotel in the province of La Libertad in El Salvador. The data is analyzed to determine the initial conditions of the technical problem. An algorithm for Inventive Problem Solving is applied in order to develop a system that performs the water supply automatically, receives signals by means of level sensors, starts or stops the pumps (if necessary), and detects water leaks with the use of pressure sensors, reducing the waste of water and electricity.

Global positioning with animal‐borne pressure sensors

AbstractOver the past decades, tracking technologies have become more ubiquitous and helped uncover crucial spatiotemporal relationships in nature. In order to apply these technologies to small animals and reduce any potential adverse impact of devices, geopositioning methodologies compatible with lightweight devices are highly sought after. Measured by lightweight geolocators, atmospheric pressure provides an untapped opportunity for global geopositioning, as its natural temporal variation is unique to each location.In this study, we estimate the position of birds by comparing pressure data recorded by the geolocator with reference data from a global weather reanalysis database. The method produces a likelihood map of the position based on (1) a mask of the locations for which the ground‐level elevation matches the pressure measured by the geolocator and (2) a mismatch between the temporal time series measured by the geolocator and the reanalysis dataset. This new method is introduced step by step and applied to 16 tracks of nine long‐ and short‐distance migrant species.Using known positions of double‐tagged individuals (light and pressure data), we demonstrate that our method is almost three times more accurate than light‐based positioning with an average error of 44 km in our trials. In contrast to the traditional light‐based approach, pressure geolocation can provide useful information for short stationary periods (less than a day) and is not affected by the equinox problem nor by any shading effects due to weather or animal behaviour. To facilitate the application of the method, we developed an R packageGeoPressureR, together with a user guideGeopressureManualand starting codeGeoPressureTemplate.The use of pressure sensors to position animals has the potential to become widespread thanks to the combination of both affordable lightweight devices (<0.4 g) and this method to estimate position of the device precisely and accurately. In particular, such devices can now be applied to short‐distant migrants (>100 km), forest‐dwelling species, nocturnal animals and altitudinal migrants.

Performance improvement of cardiorespiratory measurements using pressure sensors with mechanical coupling techniques

Monitoring heart rate and breathing is essential in understanding the physiological processes for sleep analysis. Polysomnography (PSG) system have traditionally been used for sleep monitoring, but alternative methods can help to make sleep monitoring more portable in someone's home. This study conducted a series of experiments to investigate the use of pressure sensors placed under the bed as an alternative to PSG for monitoring heart rate and breathing during sleep. The following sets of experiments involved the addition of small rubber domes - transparent and black - that were glued to the pressure sensor. The resulting data were compared with the PSG system to determine the accuracy of the pressure sensor readings. The study found that the pressure sensor provided reliable data for extracting heart rate and respiration rate, with mean absolute errors (MAE) of 2.32 and 3.24 for respiration and heart rate, respectively. However, the addition of small rubber hemispheres did not significantly improve the accuracy of the readings, with MAEs of 2.3 bpm and 7.56 breaths per minute for respiration rate and heart rate, respectively. The findings of this study suggest that pressure sensors placed under the bed may serve as a viable alternative to traditional PSG systems for monitoring heart rate and breathing during sleep. These sensors provide a more comfortable and non-invasive method of sleep monitoring. However, the addition of small rubber domes did not significantly enhance the accuracy of the readings, indicating that it may not be a worthwhile addition to the pressure sensor system.

Improvement of Baro Sensors Matrix for Altitude Estimation.

The article presents the use of barometric sensors to precisely determine the altitude of a flying object. The sensors are arranged in a hexahedral spatial arrangement with appropriately spaced air inlets. Thanks to the solution used, the range of measurement uncertainty can be reduced, resulting in a lower probability of error during measurement by improving the accuracy of estimation. The paper also describes the use of pressure sensors in complex Tracking Vertical Velocity and Height systems, integrating different types of sensors to highlight the importance of this single parameter. The solution can find application in computational systems using different types of data in Kalman filters. The impact of pressure measurements in a geometric system with different spatial orientations of sensors is also presented. In order to compensate for local pressure differences, e.g., in the form of side wind gusts, an additional reference sensor was used, making the developed solution relevant for applications such as industrial ones.

Smart mattress integrated with pressure sensor and IoT functions for sleep apnea detection

Obstructive Sleep Apnea (OSA) is the main reason for sleep-associated respiration disorders, wherein respiration stops and begins evolved again and again at some pointing sleep. Sleep-disordered respiration can affect our common health protection and quality of life. This look targets at detecting sleep posture and sleep-disordered respiration through measuring the sensory reaction of a pressure sensor and respiration microphone sensor set up with mattresses, pillowcases, and positional sleep apnea. Three positions use of pressure sensors were used to analyze. The respiration microphone sensor is used for the duration of sleep and to measure breathing levels. In this work, we have got an advanced sleep monitoring system based on an inattentive method. Internet of Things (IoT) is used to transmit information saved in sensors and displayed in internet applications. Helps us without problems displaying gold coins and gold time periods.

Interventions for preventing and reducing the use of physical restraints of older people in general hospital settings.

Interventions for preventing and reducing the use of physical restraints of older people in general hospital settings.

Active system for reduction of noise parameters of car muffler with the use of pressure sensors based on silicon microcrystals

Purpose: The article contains the results of research and development of a system for active noise damping of an automobile engine. The proposed system of active noise suppression can significantly reduce the sound pressure level in the frequency band up to 500 Hz. The robotic principle of the developed system is based on the addition of an additional buffer tank with a variable volume in the silencer system. The use of high-temperature sensors with strain gauges based on silicon microcrystals to obtain information on the parameters of sound vibrations arising during the exhaust gas outflow made it possible to create a control system for changing the volume of the buffer tank. The results of testing the proposed system of active noise suppression of an internal combustion engine are presented. Design/methodology/approach: The active noise suppression system based on the Helmholtz resonator used tools to control general noise levels, experimental tests, complex mathematical modelling of acoustic processes in Solidworks, taking into account the conditions of propagation and attenuation of sound energy by intermediate closed volumes. Findings: The use of an additional resonator chamber with variable volume in the exhaust muffler of the internal combustion engine allowed to reduce the resonant phenomena in the zone of low-frequency pulsations of exhaust gas pressure from 57 Hz to 43 Hz at frequency drift in the range of 310… 350 Hz, which significantly improved its noise characteristics. Research limitations/implications: For further research, to improve the characteristics of the active noise suppression system, it is advisable to consider the use of several inadditional cameras of the Helmholtz resonator and to clarify the algorithm of the controller in transient modes of engine operation. Practical implications: The developed design of active noise reduction is simpler in comparison with analogs and allows reducing the noise of exhaust gases in a low-frequency range. Originality/value: To reduce the noise, a variable-volume Helmholtz resonator was used, the efficiency of which is provided by high-temperature sensors of the original design.

Integration of opencv raspberry pi 3b+ and camera sensor in access control of vehicle ignition key system

The use of sensors for safety and comfort in vehicles has increased, as in several studies that are being discussed, including the use of pressure sensors for applications in the TPMS system or face recognition system security. The purpose of this research is to reduce vehicle theft that is happening right now. This system consists of a face recognition system. This reason is based on the ineffectiveness of the vehicle handlebar / steering lock. But in this study, a vehicle safety prototype was designed with a face recognition method in the hope that this prototype was designed to provide a sense of comfort, security and also the vehicle becomes a privacy vehicle. The method used is the Local Binary Path Histogram method to detect image objects and a small camera to capture images of the face, using the Raspberry Pi as a tool control center (in which the process occurs: Scanning, Extracting, Comparing, Matching, and all have been incorporated in OpenCV). The output of this study is the face that has been recorded in the database as access to open access to vehicle security. The conclusion of this research is the process of facial recognition in real time activating the vehicle ignition lock system.

PD06-03 CATHETER-FREE WIRELESS MEASUREMENT OF FELINE BLADDER PRESSURES USING INTRAVESICAL SENSOR

You have accessJournal of UrologyUrodynamics/Lower Urinary Tract Dysfunction/Female Pelvic Medicine: Incontinence: Evaluation (Urodynamic Testing) (PD06)1 Apr 2020PD06-03 CATHETER-FREE WIRELESS MEASUREMENT OF FELINE BLADDER PRESSURES USING INTRAVESICAL SENSOR Steve Majerus*, Kangli Deng, Brett Hanzlicek, Binit Panda, James Mrowca, Dennis Bourbeau, and Margot Damaser Steve Majerus*Steve Majerus* More articles by this author , Kangli DengKangli Deng More articles by this author , Brett HanzlicekBrett Hanzlicek More articles by this author , Binit PandaBinit Panda More articles by this author , James MrowcaJames Mrowca More articles by this author , Dennis BourbeauDennis Bourbeau More articles by this author , and Margot DamaserMargot Damaser More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000833.03AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: In research animal models, catheterization for cystometry requires anesthesia which affects neuro-urological pathways, or animal restraint, limiting measurement time and social behaviors surrounding natural bladder filling and micturition. To overcome this, we developed a catheter-free, wireless, intravesical pressure sensor for use in conscious, untethered felines. This study validated sensor function and physiologic outcomes over 4-week implantations, including (to our knowledge) the first untethered catheter-free wireless recordings of bladder pressure during bladder filling and voiding. METHODS: Sensor performance was first validated on the bench. Sensors were then encapsulated in layers of medical epoxy and silicone and sterilized by ethylene oxide gas prior to implantation. Implantations were performed on 6 male felines: 2 were sham (no device), 2 implants were inactive devices, and 2 used active devices measuring 18 mm x 12 mm x 5.6 mm. Devices were implanted into the bladder lumen through a 10-cm detrusor incision, which was stretched on insertion and then sutured. Anesthetized cystometry and urine collection was performed immediately before and after surgery, and at 2 and 4 weeks after implantation. Conscious data collection and behavioral video recordings were performed 3 times/week. Data collection used a small animal-worn radio harness which received sensor transmissions and logged data to a MicroSD card. Devices were explanted after 4 weeks. RESULTS: All animals showed a similar decrease in bladder capacity following surgery (sham surgery and implant). All devices remained patent without obstructing the bladder for 4 weeks; one device stopped transmitting at 12 days and one worked through 4 weeks. Wireless pressure data was linearly correlated with spontaneous reflex contractions during anesthetized urodynamics (R2 = 0.96). Conscious data recording was performed on 11 occasions, producing over 200 minutes of catheter-free pressure recordings. Animals entered and used litter boxes freely while data were recorded to the radio harness. Recorded pressures during voiding were confirmed against simultaneous video recording. CONCLUSIONS: Small wireless, intravesical sensors permitted catheter-free recordings of bladder pressure in felines for 30 days, including voluntary voiding contractions. Translation of this technology could enable urethrally-inserted sensors for catheter-free, wireless ambulatory urodynamics over longer time periods than is feasible with catheters. Source of Funding: This work was funded by the NIH Stimulating Peripheral Activity to Relieve Conditions (SPARC) program, NIH grant number OT2OD023873. © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e155-e155 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Steve Majerus* More articles by this author Kangli Deng More articles by this author Brett Hanzlicek More articles by this author Binit Panda More articles by this author James Mrowca More articles by this author Dennis Bourbeau More articles by this author Margot Damaser More articles by this author Expand All Advertisement PDF downloadLoading ...

SPARC: Catheter‐Free Wireless Measurement of Feline Bladder Pressures Using Intravesical Sensor

Introduction and ObjectiveIn research animal models, catheterization for cystometry requires anesthesia which affects neuro‐urological pathways, or animal restraint, limiting measurement time and social behaviors surrounding natural bladder filling and micturition. To overcome this, we developed a catheter‐free, wireless, intravesical pressure sensor for use in conscious, untethered felines. This study validated sensor function and physiologic outcomes over 4‐week implantations, including (to our knowledge) the first untethered catheter‐free wireless recordings of bladder pressure during bladder filling and voiding.MethodsSensor performance was first validated on the bench. Sensors were then encapsulated in layers of medical epoxy and silicone and sterilized by ethylene oxide gas prior to implantation. Implantations were performed on 6 male felines: 2 were sham (no device), 2 implants were inactive devices, and 2 used active devices measuring 18 mm × 12 mm × 5.6 mm. Devices were implanted into the bladder lumen through a 10‐cm detrusor incision, which was stretched on insertion and then sutured. Anesthetized cystometry and urine collection was performed immediately before and after surgery, and at 2 and 4 weeks after implantation. Conscious data collection and behavioral video recordings were performed 3 times/week. Data collection used a small animal‐worn radio harness which received sensor transmissions and logged data to a MicroSD card. Devices were explanted after 4 weeks.ResultsAll animals showed a similar decrease in bladder capacity following surgery (sham surgery and implant). All devices remained patent without obstructing the bladder for 4 weeks; one device stopped transmitting at 12 days and one worked through 4 weeks. Wireless pressure data was linearly correlated with spontaneous reflex contractions during anesthetized urodynamics (R2 = 0.96). Conscious data recording was performed on 11 occasions, producing over 200 minutes of catheter‐free pressure recordings. Animals entered and used litter boxes freely while data were recorded to the radio harness. Recorded pressures during voiding were confirmed against simultaneous video recording.ConclusionsSmall wireless, intravesical sensors permitted catheter‐free recordings of bladder pressure in felines for 30 days, including voluntary voiding contractions. Translation of this technology could enable urethrally‐inserted sensors for catheter‐free, wireless ambulatory urodynamics over longer time periods than is feasible with catheters.Support or Funding InformationThis work was funded by the NIH Stimulating Peripheral Activity to Relieve Conditions (SPARC) program, NIH grant number OT2OD023873.

Flow-speed-controlled quality optimisation for one-shot-hybrid RTM parts

This work describes a model-based methodology to improve the bonding quality between the metal and composite constituents of one-shot-hybrid resin transfer moulding (OSH-RTM) parts. In order to reduce void induced defects in the interface an ideal flow front velocity needs to be achieved. This ideal flow front velocity is characterised by capillary rise experiments at the used carbon fibre textile. The flow front velocity during mould filling is controlled by the use of pressure sensors and Darcy’s law. Therefore, viscosity characterisation of the resin system and permeability measurements of the preform were carried out. The interface of the produced OSH-RTM roof bar for a car is tested on a component test rig imitating the load of a side impact at a car. A t-test was carried out to prove that the flow-speed-controlled injection strategy is advantageous compared to a constant mass flow injection by means of a higher maximum load transferable by the interface of the hybrid part.

A self-healing, robust adhesion, multiple stimuli-response hydrogel for flexible sensors.

Ionic hydrogels have great application potential in human index monitoring and wound treatment, such as in wearable sensors, wound dressings, and ionic skin. However, the design of a hydrogel achieving the synergistic characteristics of excellent mechanical properties, robust adhesion, and multiple stimuli-responses remains a critical challenge. Herein, by introducing negatively charged clay nanosheets, we report a smart ionic Gelatin/PAAm/Clay hydrogel (GPNs gel) with a high conductivity of 10.87 mS cm-1. The as-prepared gel exhibits excellent self-healing properties, robust adhesion (interfacial toughness of up to 485 J m-2 with pigskin), and multiple stimuli-responses driven by salt ions, pH, and stress. Based on this hydrogel, a capacitive sensor has also been designed, which provides linear responses over a wide range (applied pressure up to 2 kPa) and sensitively monitors human motion. In addition, the gel also displays good biocompatibility with human lung embryonic (MRC-5) cells. These characteristics demonstrate that the GPNs gel is an ideal candidate for developing flexible sensor devices.

Electronic Design of a Cotton Harvester Yield Monitor Calibration System

Several yield monitors are available for use on cotton harvesters, but none are able to maintain yield measurement accuracy across cultivars and field conditions that vary spatially and/or temporally. Thus, the utility of yield monitors as tools for on-farm research is limited unless steps are taken to calibrate the systems as cultivars and conditions change. This technical note details the electronic system design for a harvester-based yield monitor calibration system for basket-type cotton strippers. The system was based upon the use of pressure sensors to measure the weight of the basket by monitoring the static pressure in the hydraulic lift cylinder circuit. To ensure accurate weighing, the system automatically lifted the basket to a target lift height, allowed the basket time to settle, then weighed the contents of the basket. The software running the system was split into two parts that were run on an embedded low-level micro-controller and a mobile computer located in the harvester cab. The system was field tested under commercial conditions and found to measure basket load weights within 2.5% of the reference scale. As such, the system was proven to be capable of providing an on-board auto-correction to a yield monitor for use in multi-variety field trials.

Man-Machine-Interface Software Design of a Cotton Harvester Yield Monitor Calibration System

Several yield monitors are available for use on cotton harvesters, but none are able to maintain yield measurement accuracy across cultivars and field conditions that vary spatially and/or temporally. Thus, the utility of yield monitors as tools for on-farm research is limited unless steps are taken to calibrate the systems as cultivars and conditions change. This technical note details the man-machine-interface software system design portion of a harvester-based yield monitor calibration system for basket-type cotton strippers. The system was based upon the use of pressure sensors to measure the weight of the basket by monitoring the static pressure in the hydraulic lift cylinder circuit. To ensure accurate weighing, the system automatically lifted the basket to a target lift height, allowed basket time to settle, then weighed the contents of the basket. The software running the system was split into two parts that were run on an embedded low-level micro-controller, and a mobile computer located in the harvester cab. The system was field tested under commercial conditions and found to measure basket load weights within 2.5% of the reference scale. As such, the system was proven to be capable of providing an on-board auto-correction to a yield monitor for use in multi-variety field trials.

Embedded Micro-Controller Software Design of a Cotton Harvester Yield Monitor Calibration System

Several yield monitors are available for use on cotton harvesters, but none are able to maintain yield measurement accuracy across cultivars and field conditions that vary spatially and/or temporally. Thus, the utility of yield monitors as tools for on-farm research is limited unless steps are taken to calibrate the systems as cultivars and conditions change. This technical note details the embedded micro-controller software system design portion of a harvester-based yield monitor calibration system for basket-type cotton strippers. The system was based upon the use of pressure sensors to measure the weight of the basket by monitoring the static pressure in the hydraulic lift cylinder circuit. To ensure accurate weighing, the system automatically lifted the basket to a target lift height, allowed the basket time to settle, and then weighed the contents of the basket. The software running the system was split into two parts, which were run on an embedded low-level micro-controller and a mobile computer located in the harvester cab. The system was field tested under commercial conditions and found to measure basket load weights within 2.5% of the reference scale. As such, the system was proven to be capable of providing an on-board auto-correction to a yield monitor for use in multi-variety field trials.

Исследование рельсового электромагнитного источника плазменной струи

Abstract The study of elements of rail electromagnetic accelerator (railgun), aimed at studying the mechanism of formation of the dense and free from impurities plasma jet with high kinetic energy is presented. The accelerator was tested with pulsed gas inlet, different shape and length of electrodes, as well as with an additional magnetic field created by external conductors with current. The method controlling of plasma jet parameters on test bench with the use of pressure sensor and infrared video camera was developed. The dependence of the pressure of deuterium plasma flow on distance to the accelerator was investigated. The kinetic energy of the jet was estimated.

An Implantable Sensorized Lead for Continuous Monitoring of Cardiac Apex Rotation.

Changes in the pattern or amplitude of cardiac rotation have been associated with important cardiovascular diseases, including Heart Failure (HF) which is one of the major health problems worldwide. Recent advances in echocardiographic techniques have allowed for non-invasive quantification of cardiac rotation; however, these examinations do not address the continuous monitoring of patient status. We have presented a newly developed implantable, transvenous lead with a tri-axis (3D) MEMS gyroscope incorporated near its tip to measure cardiac apex rotation in the three-dimensional space. We have named it CardioMon for its intended use for cardiac monitoring. If compared with currently proposed implantable systems for HF monitoring based on the use of pressure sensors that can have reliability issues, an implantable motion sensor like a gyroscope holds the premise for more reliable long term monitoring. The first prototypal assembly of the CardioMon lead has been tested to assess the reliability of the 3D gyroscope readings. In vitro results showed that the novel sensorized CardioMon lead was accurate and reliable in detecting angular velocities within the range of cardiac twisting velocities. Animal experiments will be planned to further evaluate the CardioMon lead in in vivo environments and to investigate possible endocardial implantation sites.

EVALUATION OF AGRICULTURAL TRACTOR SEAT COMFORT WITH A NEW PROTOCOL BASED ON PRESSURE DISTRIBUTION ASSESSMENT.

Professional drivers have been found to be at a high risk of developing low back pain due to prolonged sitting and vehicle vibration. In a previous survey carried out on 1,155 tractor drivers, tractor vibration and/or incorrect posture while driving were found to cause low back disorders in more than 80% of the interviewed drivers. In this context, the present research introduces a new evaluation protocol to assess the ergonomic characteristics of agricultural tractor seats through the use of pressure sensors, taking into account both static and dynamic conditions. The degree of comfort was defined by analyzing the pressure distribution exerted by a sample of 12 drivers sitting on two seats in five different operating conditions. The pressure distribution values thus obtained were compared with the corresponding pressures recorded with the 12 drivers sitting on a reference seat (rigid seat, backrest, and suspension) designed for the purpose. From the comparison, it was possible to define a comfort index (CI) that allowed an objective assessment of the two seats. Statistical analysis showed that the CIs of the two seats were significantly different in all five operating conditions. Moreover, the two seats showed different CIs as a function of the operating condition. Although less comfortable, one seat showed almost constant CI values in all five operating conditions. Conversely, the other seat showed a progressively decreasing CI from the static condition to the uneven ground condition.