Pressure Feedback Research Articles

A Review of Foot pressure Measurement of Diabetic and Analysis Patients

Peripheral neuropathy, the main risk factor for diabetic foot ulcers (DFU), causes loss of protective feeling and is linked to very high plantar pressures. The goal of DFU preventive techniques is to lower these elevated plantar pressures. However, there are a number of limitations to the evidence that supports the connection between plantar pressure and DFUs, which could account for the poor prediction accuracy found in prospective studies. Most research measures the vertical, as opposed to the shear, barefoot plantar pressure in lab settings as opposed to in real-world activities. Previous DFU location-specific pressure was not well studied. Prior research has mostly concentrated on walking; however activity tracking studies indicate that more time is spent on other weight-bearing tasks, when a longer duration of lower "peak" plantar pressure may be applied. This suggests that a measure of the cumulative pressure applied over time might be more pertinent than peak pressure, however more investigation is required. Further research is needed, however studies have shown that delivering pressure feedback may lessen plantar pressures. This is an emerging potential use of smart technology. To increase our knowledge of the pressures that lead to DFUs and the efficacy of therapies, more pressure assessments pertaining to location-specific pressures pertaining to all weight-bearing activities are needed.

Seasonal slow slip in landslides as a window into the frictional rheology of creeping shear zones.

Whether Earth materials exhibit frictional creep or catastrophic failure is a crucial but unresolved problem in predicting landslide and earthquake hazards. Here, we show that field-scale observations of sliding velocity and pore water pressure at two creeping landslides are explained by velocity-strengthening friction, in close agreement with laboratory measurements on similar materials. This suggests that the rate-strengthening friction commonly measured in clay-rich materials may govern episodic slow slip in landslides, in addition to tectonic faults. Further, our results show more generally that transient slow slip can arise in velocity-strengthening materials from modulation of effective normal stress through pore pressure fluctuations. This challenges the idea that episodic slow slip requires a narrow range of transitional frictional properties near the stability threshold, or pore pressure feedbacks operating on initially unstable frictional slip.

Pressure feedback system for flow separation mitigation in scramjet intakes

Shock Wave Boundary Layer Interactions (SWBLI) occur due to the convergence of a shock wave and a viscous boundary layer. The resulting separation bubble is a major setback for the performance of high-speed air intakes. This paper presents a numerical investigation into the potential of a Pressure Feedback Technique (PFT) to alleviate shock-induced flow separation within a Scramjet engine intake operating at Mach 4. The PFT is a novel self-sustaining flow control technique that combines simultaneous suction and injection. The two main output parameters used to support the hypothesis of the present study are the size of the separation bubble as well as the total pressure recovery at the isolator outlet. The most prominent observation of this study is that with the installation of the PF tubes, the total pressure recovery at the exit is noted to rise. The effectiveness of the pressure feedback technique in reducing the intensity of the separation bubbles is found to depend on the diameter of the PFT, pitch-to-diameter ratio, and PFT tube design.

Few-mode optical fiber-based flexible pressure feedback tentacle doped with fluorescence temperature pointer

Abstract In this paper, a flexible fiber pressure feedback whisker is proposed, which consists of a water droplet shaped polydimethylsiloxane (PDMS) elastomer with an embedded balloon shaped few mode fiber. The mechanical sensing performance of the device was analyzed and optimized using a combination of finite element method and beam propagation method (BPM). The built-in cladding corroded few-mode fiber increases pressure sensitivity by more than four times. The collection efficiency of fluorescence signal is improved by cladding corrosion. The PDMS elastomer was doped with upconversion nanoparticles NaYF4:Yb, Er@NaYF4 in order to achieve temperature measurement by fluorescence intensity ratio technology. The combination of fluorescence signal and interference spectrum can not only achieve real-time and accurate pressure detection at different temperatures, but also incorporate fluorescent materials into flexible bionic skin for temperature self-compensation, which has potential application value for the development of bionic fiber micro-nano sensing and control devices.

Electrification of Agricultural Machinery: One Design Case of a 4 kW Air Compressor

In response to the global pursuit of net-zero carbon emissions, the electrification of agricultural machinery is becoming a significant research and development trend. This study introduces the overall design of a 4 kW air compressor aimed at achieving a green vision for agricultural machinery. The design focuses on providing continuous and stable power and air output using a lithium-ion battery. Durability and cost-effectiveness are prioritized, with a particular emphasis on the Arduino system for integrating battery and motor systems to withstand harsh conditions and ensure ease of maintenance. A permanent magnet brushless motor was selected as the power source, paired with an optimized pulley to supply the proper torque to the air compressor. The system employs an Arduino-based feedback control sensor for air pressure regulation, ensuring energy efficiency. The primary energy source is a 48 V lithium iron phosphate battery, known for its high energy density and safety. The battery design focuses on system integration, addressing specific environmental discharge requirements. The embedded battery management system provides thermal and lifecycle parameter estimation, guaranteeing long-duration power supply and safe operation under various conditions. Unlike traditional fuel-driven systems, lithium iron phosphate batteries do not emit harmful gases, aligning with environmental standards. System integration testing demonstrated that the air pressure feedback control effectively meets the energy-saving requirements by digitally reducing power output as air accumulates in the chamber. Bench testing confirmed that the system performs as designed, achieving the desired results and advancing the goal of sustainable agricultural machinery.

Experimental investigation of aerodynamic behavior of wood chips in fluidized bed reactors as a sustainable biomass fuel

Sustainable energy solutions are necessary in the current manufacturing advancements, where a need is being pressed upon biomaterial-based processes. This study examines the aerodynamics of wood chip biomass in fluidized-bed reactors, an essential aspect of sustainable biomass fuel technologies. Through experimental investigations, the current methodology determined the minimum fluidization rates for particles of four distinct sizes and compared these with theoretical prediction-based calculations. A novel laboratory setup featuring a Differential Pressure Feedback Exhaust gas recirculation (DPFE) sensor system was developed to measure these processes continuously to advance the enhancements of the precision and reliability of the findings. Key results include the successful adaptation of the Ergun equation for wood chips, herewith accommodating observed deviations in pressure drops within specific fluidization ranges. This adaptation, along with real-time data tracking of air phase changes using a multifunction measuring device, revealed critical insights into turbulence patterns and particle movement. These results and findings are consistent with theoretical models and underscore the potential to optimize wood chip use in fluidized-bed reactors. The study's results also contribute significantly to the field of renewable energy as they offer a validated methodological approach and practical modifications to existing theoretical models.

Neuroprosthetic contact lens enabled sensorimotor system for point-of-care monitoring and feedback of intraocular pressure

The wearable contact lens that continuously monitors intraocular pressure (IOP) facilitates prompt and early-state medical treatments of oculopathies such as glaucoma, postoperative myopia, etc. However, either taking drugs for pre-treatment or delaying the treatment process in the absence of a neural feedback component cannot realize accurate diagnosis or effective treatment. Herein, a neuroprosthetic contact lens enabled sensorimotor system is reported, which consists of a smart contact lens with Ti3C2Tx Wheatstone bridge structured IOP strain sensor, a Ti3C2Tx temperature sensor and an IOP point-of-care monitoring/display system. The point-of-care IOP monitoring and warning can be realized due to the high sensitivity of 12.52 mV mmHg−1 of the neuroprosthetic contact lens. In vivo experiments on rabbit eyes demonstrate the excellent wearability and biocompatibility of the neuroprosthetic contact lens. Further experiments on a living rate in vitro successfully mimic the biological sensorimotor loop. The leg twitching (larger or smaller angles) of the living rat was demonstrated under the command of motor cortex controlled by somatosensory cortex when the IOP is away from the normal range (higher or lower).

Underwater fluid-driven soft dock for dynamic recovery of AUVs with improved pose tolerance

Recovering autonomous underwater vehicles (AUVs) by a mobile platform is a complex challenge. Traditional docking stations require strict pose deviation from the underwater vehicle. To overcome this issue, we propose a novel solution: an in-situ fluid-driven soft dock. This system comprises three soft robotic manipulators that possess guiding, capturing, and securing functionalities, respectively. We present the design, fabrication, and control methods for each manipulator considering the requirements of underwater docking operations. The theoretically allowable docking pose deviation range during AUV docking is analyzed. Additionally, the required force of soft grippers was evaluated through simulation and equivalent experimental tests. To enable dynamic recovery of AUVs while the soft robotic manipulators remain mobile on the experimental platform, we introduce a hydraulic control method based on attitude and pressure feedback. The test results indicate that the designed soft manipulators can operate and maintain good sealing performance under an external pressure of no less than 11 MPa. Moreover, the soft dock successfully recovered and secured AUVs of two different diameters in 20 dynamic tests, achieving a 90% success rate with a maximum AUV velocity of 1.6 m/s.

Bipedal robot center of pressure feedback simulation for center of mass learning

This research aims to create a walking bipedal robot with center of pressure feedback simulation for the center of mass learning, describe its feasibility for learning, describe students' motivation to learn, and describe students' science literacy after using it. The research method used ADDIE (analysis, design, development, implementation, and evaluation). The research data was obtained using a motivation scale questionnaire, science literacy scale, and feasibility scale. The research sample was 48 people; after the research obtained, the simulation of bipedal robot pressure center feedback for center of mass learning can be implemented with the principle of the robot's center of mass detected on the sole of the robot's foot equipped with a force sensitive resistor (FSR) sensor, the position of the center of mass is visible on the monitor screen as a center of mass learning, so that it can motivate students to learn and improve students' science literacy. This can be seen from the feasibility scale score, motivation scale, and science literacy scale of 4.133, 4.072, and 4.067 (scale 1 to 5), respectively, in the "good" category.

Neural adaptive dynamic surface control for position tracking of electrohydraulic servo systems based on extended state observer

High-performance motion tracking of electro-hydraulic servo systems plays an important role in developing industrial technology. However, the system itself has parameter uncertainty, uncertain nonlinearity, and measurement noise, significantly decreasing the performance of conventional controllers designed based on nominal models. To improve the tracking performance of electro-hydraulic servo systems, an adaptive dynamic surface control method combining extended state observer and radial basis function neural network is proposed. Firstly, an extended state observer combining neural network output and parameter adaptation technology is designed without the need for speed and pressure feedback to observe the system’s unknown state variables and nonlinear matched disturbance. The design of neural networks is used to approximate mismatched disturbance with significant nonlinearity online. Then, the proposed extended state observer is introduced into the neural adaptive backstepping design, effectively compensating for simultaneous matched and mismatched disturbances, thereby suppressing most of the uncertain nonlinearity of the system. Meanwhile, online update of uncertain parameters further improves the tracking performance of the controller. In addition, the introduction of dynamic surface overcomes the “explosion of complexity” issue in backstepping design. The rigorous stability of the closed-loop system is proved by the Lyapunov stability theory. Finally, the effectiveness of the proposed controller is validated through comparative experiments on valve-controlled hydraulic cylinder.

Hydrodynamic Thrust Bearing Test Rig with Novel Bearing Alignment System

Abstract This study presents the design and development of a new hydrodynamic thrust bearing test rig with a novel (patent pending) hydrodynamic pressure feedback bearing alignment control system. The bearing alignment system maintains even distribution of thrust load across the bearing thrust pads using active hydrodynamic pressure as input to manipulate bearing orientation with stepper motors. The test rig is used to conduct performance evaluation of fixed geometry hydrodynamic thrust bearings with variable taper depths. The influence of helical taper angle, rotational speed, and applied load on key performance characteristics including minimum oil film thickness (MOFT), hydrodynamic pressure distribution, and bearing temperature is presented and analyzed. A numerical model based on the Reynolds equation is used to support the experimental results obtained. Trends in performance established by the numerical analysis show mutually agreeable results compared to experimental data. The average percent deviation of the experimentally gathered change in MOFT as load is increased with respect to the numerically predicted values is 24%. Comparison of experimental to numerical pressure distribution data shows an overall average percent deviation of 32%.

A 4-DoF wearable hand device for haptic rendering of surfaces and edges

We present a 4-degrees-of-freedom (4-DoF) wearable haptic device for the palm, able to provide the sensation of interacting with slanted surfaces and edges. It is composed of a static upper body, secured to the back of the hand, and a mobile end-effector, placed in contact with the palm. They are connected by two articulated arms, actuated by four servo motors housed on the upper body and along the arms. The end-effector is a foldable flat surface that can make/break contact with the palm to provide pressure feedback, move sideways to provide skin stretch and tangential motion feedback, and fold to elicit the sensation of interacting with different curvatures. The paper presents the design of the wearable haptic device, together with its mobility, statics, and manipulability, as well as direct, inverse, and differential kinematics. We also present a position control scheme for the device, which is then quantitatively evaluated.

Pre-supernova stellar feedback in nearby starburst dwarf galaxies

Stellar feedback in dwarf galaxies remains, to date, poorly explored, yet is crucial to understanding galaxy evolution in the early Universe. In particular, pre-supernova feedback has recently been found to play a significant role in regulating and disrupting star formation in larger spiral galaxies, but it remains uncertain if it also plays this role in dwarfs. We study the ionised gas properties and stellar content of individual star-forming regions across three nearby, low-metallicity ($12+ O/H 7.5$), dwarf ($M_* odot $), starburst ($ SFR -2.8$) galaxies (J0921, KKH046, and Leo P) to investigate how massive stars influence their surroundings and how this influence changes as a function of environment. We extracted integrated spectra of 30 HII regions from archival VLT/MUSE integral field spectroscopic observations of these three dwarf starburst galaxies. We fitted the HII regions' main emission lines with Gaussian profiles to derive their oxygen abundances, electron densities, and luminosities, and we used the Stochastically Ligthing Up Galaxies ( SLUG ) code to derive the stellar mass, age, and bolometric luminosity of the stellar populations driving the HII regions. We quantified two pre-supernova stellar feedback mechanisms, namely the direct radiation pressure and photoionisation feedback, and explored how feedback strength varies with HII region properties. Our findings suggest that stellar feedback has less of an impact on evolved regions, with both the pressure of the ionised gas and the direct radiation pressure decreasing as a function of HII region size (i.e. the evolutionary stage). We find that these stellar feedback mechanisms are also dependent on the metallicity of the HII regions. These findings extend results from stellar feedback studies of more massive star-forming galaxies to the low-mass, low-metallicity regime. In addition, we conclude that the use of stochastic stellar population models significantly affects the relationships found between feedback-related pressure terms and HII region properties, and in particular that non-stochastic models can severely underestimate the bolometric luminosity of low-mass stellar populations.

Experimental study of a new technique for minimally invasive percutaneous nephrolithotomy: intelligent pressure-controlled minimally invasive percutaneous nephrolithotomy

BackgroundTo test the reliability and safety of a newly invented technique for minimally invasive percutaneous nephrolithotomy, intelligent pressure-controlled minimally invasive percutaneous nephrolithotomy (IPC-MPCNL).MethodsEighteen kidneys of nine female pigs were randomly divided into three groups. Those in Groups A and B underwent IPC-MPCNL through the new system composed of a pressure-measuring MPCNL suctioning sheath and an irrigation and suctioning platform with pressure feedback control. The infusion flow rate was 500 ml/min in Group A and 750 ml/min in Group B. Those in Group C underwent MPCNL at an infusion flow rate of 500 ml/min. The renal pelvic pressure (RPP) monitored by a ureteral catheter and that monitored by the pressure-measuring sheath in Groups A and B were compared. The RPP in Group C was monitored by a ureteral catheter.ResultsThe RPP measured by the pressure-measuring sheath and that measured by the ureteral catheter in Group A was − 5.59 ± 1.95 mmHg and 4.46 ± 2.08 mmHg, respectively. The RPP measured by the pressure-measuring sheath and that measured by the ureteral catheter in Group B was − 4.00 ± 2.01 mmHg and 5.92 ± 2.05 mmHg, respectively. Hence, the RPPs measured by the pressure-measuring sheath in Groups A and B were consistent with those measured by the ureteral catheter. The RPP in Group C was 27.75 ± 5.98 mmHg (large fluctuations).ConclusionsIPC-MPCNL can be used to accurately monitor the RPP and maintain it within a preset safe range via suction. The new technique and the new system are safe and reliable.

Design sensitivity analysis of modal frequencies of elastic structures submerged in an infinite fluid domain

SummaryThis paper presents a numerical approach for the design sensitivity analysis of modal frequencies of elastic structures submerged in an unbounded heavy fluid domain. Because the feedback of sound pressure onto the fluid‐loaded structures has to be taken into account in this case, a fully coupled scheme which combines the structural finite element method (FEM) and the acoustic boundary element method (BEM) is employed in the numerical simulation. The resulting nonlinear eigenvalue problem created by the coupled finite element and boundary element (FE‐BE) method is converted into a generalized eigenvalue problem (GEP) of reduced dimension by using a contour integral method. The design sensitivity formulation for non‐repeated eigenvalues is derived based on an adjoint method which uses both the left and right eigenvectors, and a small GEP is formed to calculate the gradients of repeated eigenvalues. The Burton‐Miller formulation is employed to shift the fictitious eigenfrequencies and their derivatives, and the parameter setting which is beneficial to the filtering of fictitious eigenfrequencies is investigated. Numerical examples are given to verify the accuracy and effectiveness of the developed method.

On the effects of photoionization feedback on second-generation star formation in globular clusters of different masses

ABSTRACT We simulate the formation of second-generation (SG) stars in young clusters with masses of 105 and $10^6\, \mathrm{M}_{\odot }$ within $30\!-\!100\, \mathrm{Myr}$ after the formation of clusters. We assume the clusters move through a uniform interstellar medium with gas densities of 10−24 and $10^{-23}\, \mathrm{g\, cm}^{-3}$ and consider the stellar winds from asymptotic giant branch (AGB) stars, gas accretion on to the cluster, ram pressure, star formation, and photoionization feedback of our stellar systems including binary stars. We find that SG stars can be formed only within the $10^6\, \mathrm{M}_{\odot }$ cluster in the high-density simulation, where the cluster can accrete sufficient pristine gas from their surrounding medium, leading to efficient cooling required for the ignition of SG formation and sufficient dilution of the AGB ejecta. Hence, our results indicate that a denser environment is another requirement for the AGB scenario to explain the presence of multiple populations in globular clusters. On the other hand, the ionizing feedback becomes effective in heating the gas in our low-density simulations. As a result, the clusters cannot accumulate a considerable amount of pristine gas at their centre. The gas mass within the clusters in these simulations is similar to that in young massive clusters (YMCs). Hence, our studies can provide a possible reason for the lack of gas, star formation, and SG stars in YMCs. Our results indicate that the ionizing stellar feedback is not a severe problem for SG formation; rather, it can help the AGB scenario to account for some observables.

Controller Design for Electrohydraulic Actuator of Heavy-Duty Automatic Transmission Using Model Predictive Control Algorithm

High-quality shifting is an inelastic demand for the automotive industry, and it is worth exploring the design of controllers that can shift precisely according to the planned shifting strategy. This paper proposes a dynamic model of the automatic transmission up/downshift process, and the transfer function based on pressure is first given. The model was verified by comparing it with the experimentally obtained fluid pressure. Subsequently, a pressure control strategy suitable for heavy-duty automatic transmission shifting was explored by establishing a model predictive controller with pressure feedback control. Meanwhile, a Kalman filter-based observer was designed to solve the inconvenient installation of internal sensors. Finally, the proposed control model was optimised using a multi-objective genetic algorithm for the controller. The simulation results indicate that the proposed control strategy can be applied to heavy-duty vehicles for improving the shift quality.

Seismically progressive motion mechanism of earth slopes considering shear band porewater pressure feedback under earthquake excitations

The complicated seismic response of earth slopes and the transition mechanism from progressive to catastrophic motion of landslides have long been recognized as one of the most challenging research topics in geotechnical earthquake engineering. In this paper, this fundamental conundrum will be tentatively unveiled from a new perspective combining the seismic slope displacement analysis with (mechanical) dynamic porewater pressure feedback of the shear band soils against the earthquake excitation. We present both the conceptual scheme and the calculation framework to numerically study the dynamic changes of porewater pressure, shear strength parameters, and hydraulic properties of the shear band soils. Their significant influences to the change of earthquake-induced landslide movement modes are systematically investigated. Different dilation angles are chosen to characterize the shear dilation and shear contraction processes in the shear band soil, while the dynamic porewater pressure feedback in the shear band soil during the continuous seismic displacement is investigated. The results show that the seismic slope displacement and failure strongly depend on the mechanical feedback of the shear band soil. When the dilation angle is positive, the porewater pressure feedback in the shear band during the slope movement is negative, and the effective resistance stress increases, which is not susceptible to catastrophic motion. On the other hand, when the dilation angle is negative, the positive porewater pressure feedback may lead to catastrophic failure. At last, the effects of shear softening/hardening combined with dilation angle evolution on the ultimate slope movement mode are also put forward.

An Asymmetric Interlocked Structure with Modulus Gradient for Ultrawide Piezocapacitive Pressure Sensing Applications

AbstractHighly sensitive electronic skin (e‐skin) sensors with considerable operating range offer great possibilities for health care, human–‐machine interfaces, and intelligent robotics. Although subtle microstructures have been used in recent years to improve the sensitivity and sensing range of e‐skin sensors, the trade‐off between these features remains a big challenge to overcome. Here, an asymmetric interlocked gradient elastic modulus (AIGM) structure is designed for the first time to provide sufficient deformation space to the traditional interlocked structure while ensuring high sensitivity, and the gradient elastic modulus further extends the sensing range of the AIGM structure‐based sensors, which exhibit a maximum sensitivity of as high as 9.89 kPa−1 with an ultrawide working range that extends to above 530 kPa at the same time. As a demo, this sensor is integrated into an intelligent adjustable mouse platform for physiological signal monitoring, pressure feedback, and modulus adjustment, providing a viable alternative for hand disease prevention.

Development, modeling, and control of a syringe-based picoliter-scale microinjection system

Microinjection, which is widely employed in modern biology and medicine research, is a crucial method for transferring biomaterial in a single cell. Despite substantial research into microinjection automation technology, how to achieve high precision, which is crucial for quantitative analysis, has gotten scant attention. This paper offers a dual-loop control syringe-based picoliter-scale injection system, with the inner being a pneumatic servo loop with a baroreceptor providing pressure feedback and the outside being a position servo loop with a microscope providing visual feedback. Specifically, significant crawling phenomenon are found throughout the characteristic test trial, rendering the gas-liquid interface uncontrollable. To mathematically characterize this phenomenon, a theoretical model is developed that accounts for static friction, capillary force, capillary cone angle, and fluid viscous force. The genetic algorithm is used to identify difficult-to-measure and calibrate parameters. Based on the established model, an integral sliding-mode controller (ISMC) with saturation function and a PID controller for the inside loop control were established, both of which have a fast convergence rate and do not overshoot. Finally, experimentation is used to validate the designed cell injection system, demonstrating that the suggested system can regulate the smallest droplet in the tip of the needle to within 0.25 pL.