Bending Angle Measurements Research Articles

Conductive hydrogels‐based self‐sensing soft robot state perception and trajectory tracking

AbstractSoft robots face significant challenges in proprioceptive sensing and precise control due to their highly deformable and compliant nature. This paper addresses these challenges by developing a conductive hydrogel sensor and integrating it into a soft robot for bending angle measurement and motion control. A quantitative mapping between the hydrogel resistance and the robot's bending gesture is formulated. Furthermore, a nonlinear differentiator is proposed to estimate the angular velocity for closed‐loop control, eliminating the reliance on conventional sensors. Meanwhile, a controller is designed to track both structural and nonstructural trajectories. The proposed approach integrates advanced soft sensing materials and intelligent control algorithms, significantly improving the proprioception and motion accuracy of soft robots. This work bridges the gap between novel material design and practical control applications, opening up new possibilities for soft robots to perform delicate tasks in various fields. The experimental results demonstrate the effectiveness of the proposed sensing and control approach in achieving precise and robust motion control of the soft robot.

Development and Application of Shape-Memory Polymer and Alloy Composite Sheets

The authors previously developed a flexible and multi-degree-of-freedom pneumatic artificial rubber muscle that uses shape-memory polymer (SMP) sheets with an embedded electrical heating wire. The bending direction and initial shape of the muscle can be changed by utilizing the large difference in the elastic modulus below and above the glass transition temperature, shape fixity, and shape recovery of SMPs. In this study, to improve performance, we propose a shape-memory composite (SMC) sheet that consists of SMP sheets with an embedded shape-memory alloy (SMA) wire used as an electric heating wire. The mechanical properties of the previously developed SMP sheets and the proposed SMC sheets are compared through shape recovery, bending, and tensile tests using prototypes. The motion of the artificial muscle with various samples attached is evaluated through an isometric test and bending angle measurements. The experimental results confirm that the use of the SMA wire improves the production reproducibility and shape recovery of the SMP sheets without degrading other mechanical properties or actuator performance.

High sensitivity I-beam shaped polarization related vector curvature sensor with optical intensity modulation

This paper presents an innovative I-beam optical sensor combining Panda-type polarization-maintaining fiber (PMF) and thin-width polarization-maintaining photonic crystal fiber (PM-PCF), crafted using precision machining techniques like tapering and axially offset splicing. The study explores the impact of structural parameters on the device's optical performance using polarization mode coupling theory and assesses its effectiveness in vector curvature sensing, focusing on intensity sensitivity. A novel dual-parameter differential demodulation technique is proposed, achieving accurate bending angle measurements (error < 2°) through wavelength and intensity-curvature sensitivities. The experimental results highlight the device's impressive maximum intensity-curvature response of 9.36 dB/m−1. With notable responsiveness, low cross-talk, and robust polarization stability, this device holds substantial promise in the realms of fiber lasers and optical communications, serving as an ideal polarization-based, mechanically tunable optical device. Furthermore, it introduces innovative concepts and offers technological support for precision instrument measurements and related fields.

(289) Combined Therapy with Low-intensity Shockwave Therapy and Daily PDE5i Showed Better Pain Relieve and Sexual Function Improvement in Acute Phase of Peyronie Disease

Abstract Introduction To compare the efficacy and safety of daily use PDE5i and PDE5i combined with linear low-intensity shockwave therapy (Li-SWT) in the treatment of acute phase of Peyronie disease (PD). Objective 68 patients with acute PD within 6 month onset were collected. The patients were 26–56 years old with an average of 42.3 years. The patients were randomly divided into two groups, 35 of which were orally administered with 5 mg of tadalafil every night for 3 months; the other 33 received 4 times of Li-SWT with daily PDE5i. Li-SWT uses the Renova shock wave therapy device with an energy density of 0.09mJ/mm2, each time 3200 times in the penile plaque, 900 times in the left and right penile shaft, and once a week for 4 consecutive treatments as a cycle. All patients underwent ultrasound or MRI, penile bending angle measurement, improvement of subjective symptoms, and IIEF-5 scale before and after treatment. Methods 68 patients with acute PD within 6 month onset were collected. The patients were 26–56 years old with an average of 42.3 years. The patients were randomly divided into two groups, 35 of which were orally administered with 5 mg of tadalafil every night for 3 months; the other 33 received 4 times of Li-SWT with daily PDE5i. Li-SWT uses the Renova shock wave therapy device with an energy density of 0.09mJ/mm2, each time 3200 times in the penile plaque, 900 times in the left and right penile shaft, and once a week for 4 consecutive treatments as a cycle. All patients underwent ultrasound or MRI, penile bending angle measurement, improvement of subjective symptoms, and IIEF-5 scale before and after treatment. Results In the PDE5i group, the pain symptom relieve were improved in 80% patients (28 of 35 cases), while the combined group (PDE5i+Li-SWT) were improved in 90.9% patients (30 of 33 cases). The IIEF5 score in the PDE5i group improved from 13.8±7.9 to 19.5±8.1 and from 13.4±7.6 to 21.3±9.2 in the combined group, with both improvement between two groups. The plaque size were shrinkage 5 cases in PDE5i group and 12 cases in combined group, but penile curvature did not change significantly in both groups. In the PDE5i group, 5 patients had mild dizziness and back pain, while 3 patients had mild dizziness and back pain in combined group. There was no obvious adverse reaction observed for Li-SWT treatment. Conclusions Both the daily use PDE5i and the PDE5i combined with Li-SWT can improve the symptoms of acute PD patients, mainly to relieve pain and improve erectile function in some patients. The combined group had a better pain symptom relieve rate and more improvement for sexual function. The two methods can reduce PD plaque size in some cases, while both groups did not significantly change penile curvature. Both methods have good safety in the treatment of acute phase PD. Disclosure No.

Stratospheric temperature measurements from nanosatellite stellar occultation observations of refractive bending

Abstract. Stellar occultation observations from space can probe the stratosphere and mesosphere at a fine vertical scale around the globe. Unlike other measurement techniques like radiosondes and aircraft, stellar occultation has the potential to observe the atmosphere above 30 km, and unlike radio occultation, stellar occultation probes fine-scale phenomena with potential to observe atmospheric turbulence. We imaged the refractive bending angle of a star centroid for a series of occultations by the atmosphere. Atmospheric refractivity, density, and then temperature are retrieved from the bending observations with the Abel transformation and Edlén's law, the hydrostatic equation, and the ideal gas law. The retrieval technique is applied to data collected by two nanosatellites operated by Terran Orbital. Measurements were primarily taken by the GEOStare SV2 mission, with a dedicated imaging telescope, supplemented with images captured by spacecraft bus sensors, namely the star trackers on other Terran Orbital missions. The bending angle noise floor is 10 and 30 arcsec for the star tracker and GEOStare SV2 data, respectively. The most significant sources of uncertainty are due to centroiding errors due to the fairly low-resolution stellar images and telescope pointing knowledge derived from noisy satellite attitude sensors. The former mainly affects the star tracker data, while the latter limits the GEOStare SV2 accuracy, with both providing low vertical resolution. This translates to a temperature profile retrieval up to roughly 20 km for both star tracker and GEOStare SV2 datasets. In preparation of an upcoming 2023 mission designed to correct these deficiencies, SOHIP, we simulated bending angle measurements with varying magnitudes of error. The expected maximum altitude of retrieved temperature is 41 km on average for these simulated measurements with a noise floor of 0.39 arcsec. Our work highlights the capabilities of stellar occultation observations from nanosatellites for atmospheric sounding. Future work will investigate high-frequency observations of atmospheric gravity waves and turbulence, mitigating the major uncertainties observed in these datasets.

Assimilation of Radio Occultation Data Using Measurement-Based Observation Error Specification: Preliminary Results

Abstract The local spectral width (LSW) of a radio occultation (RO) observation in impact parameter representation is a useful parameter for providing information on the uncertainty associated with the RO bending angle measurement. The LSW can potentially be used to specify the bending angle observation error (BaOE) in the lower troposphere for each individual sounding. This study assesses the usefulness and limitations of LSW in representing BaOE for a global data assimilation system. A two-step scheme is proposed to derive profile-dependent BaOE from LSW. Since the LSW-based BaOE varies with each individual RO observation, it is here designated as a dynamic BaOE (DBOE) in contrast to the traditional statistics-based BaOE specification. A benchmark control run and two sensitivity experiments are conducted with continuous cycling data assimilation using the National Centers for Environmental Prediction (NCEP) Gridpoint Statistical Interpolation (GSI) and Global Forecast System (GFS). The usefulness and impact of the LSW-based DBOE are evaluated using radiosonde observations and global analyses. Results show that DBOE is able to improve the assimilation of RO data, leading to better forecast skill scores. Another experiment, in which the GSI statistical observation error of the benchmark run is replaced by the average of LSW-based DBOE, shows that the ability to assign larger weighting for high-quality observation and lower weighting for low-quality observation is the key factor for the success of the LSW-based DBOE.

A new method of retrieving atmospheric refractivity structure

ABSTRACT It is proposed to obtain information on atmospheric refractivity structure by measuring the angle of arrival (AoA) of radio signals routinely broadcast by commercial aircraft. The angle of arrival would be measured at hill-top sites using a simple two-element interferometer. Knowledge of the aircraft’s location (information conveniently contained within the broadcasts) and the AoA will enable the bending angle of the signals to be calculated. As measurable bending will only occur at grazing incidence, sources of signals either very close to the radio horizon, or at a similar height to the interferometer, are essential. The routine navigational data broadcasts from civil aircraft represent the ideal source. In areas of high air traffic density such as the UK, ~-bending angle measurements may be possible each day. Numerical weather prediction models routinely assimilate bending angles retrieved from GNSS radio occultation data, so it is anticipated that assimilation methods could be developed that are able to make good use of this new source of bending angle data. Sensitivity tests were performed to estimate the resolution of humidity retrievals assuming a target AoA accuracy of 0.01°. Simulated annealing was used to demonstrate the ability to retrieve relative humidity and mixing ratio vertical profiles using AoA measurements. It is shown that for observed AoA measurements with an accuracy of 0.01° it should be possible to retrieve relative humidity and mixing ratio vertical profiles with an accuracy of ~ and ~ g/kg respectively. An AoA accuracy of 0.01° should be achievable using hardware costing ~€10k, however further hardware development is still required.

FDM 4D printing: A low-cost approach of shape programming and assessing the shape memory properties using angle measurement methods in hot water actuation testing apparatus

With the advent of four-dimensional (4D) printing technology, manufactured components may adapt their form, size, or properties in response to external stimuli. This new 4D printing technology has opened several doors in the science, technology, engineering, and mathematics (STEM) disciplines. Fused deposition modeling (FDM) is one of the most common and cost-effective 3D printing procedures for making components out of shape-memory polymers. It is well known that programming and training are required for the 4D printing process. This work reports crucial programming methodologies that can be applied to FDM 4D printing. A detailed angle measurement scheme and the hot water actuation apparatus have been reported and discussed. This can be used to measure shape morphing in a folding or bending actuator for a variety of multifaceted applications. The angle measurement scheme presented allows for the accurate measurement of the degree of bending without causing any damage to the actuator and for real-time feedback regarding how much shape-morphing has taken place. In addition, the hot water actuation apparatus can provide high accuracy in controlling the bending angle with a simple setup. This apparatus provides a reliable and cost-effective solution to obtaining accurate bending angle measurements. Finally, when it comes to accurately measuring the shape morphing in a bending actuator, the combination of the various programming methodologies, angle measurement scheme, and hot water actuation apparatus offers a number of advantages.

Effect of Graphene Oxide on Aging Properties of Polyurethane-SBS Modified Asphalt and Asphalt Mixture.

In order to clarify the effect of the new nano-material graphene oxide on the performance of Polyurethane-SBS modified asphalt and asphalt mixture under the effect of thermal aging, the cracking process of semicircular bending test (SCB) specimens was monitored in situ based on computer vision image processing technology (OpenCV), and the modified asphalt and the cracking characteristics of the modified asphalt and mixture were further analyzed by the tests of semicircular three-point bending and aggregate contact angle measurement. The test results showed that the thermal aging effect severely damaged the composite structure formed by the cross-linking effect of Polyurethane and SBS modifier in asphalt, which intensified the degradation of Polyurethane and SBS modifier and led to great changes in the rheological properties of asphalt after aging. However, the incorporation of the new nanomaterial Graphene oxide can slow down the degradation of Polyurethane and SBS modifiers and the change of asphalt cross-linked composite structure, making the anti-cracking and anti-aging properties of Graphene oxide-Polyurethane-SBS modified asphalt mixes better than those of Polyurethane-SBS modified asphalt mixes. Therefore, the new nano-material graphene oxide added to Polyurethane-SBS modified asphalt is meaningful and feasible. Graphene oxide-polyurethane-sbs composite modified asphalt, as a new nano-material modified asphalt, is stronger against the ultraviolet and light asphalt that is prone to aging. With regards to improving the application of road projects, the results are very promising.

New impact diagnostics for cross‐validation of different observation types

AbstractNew cross‐validation diagnostics have been derived by further partitioning well‐established impact diagnostics. They are related to consistency relations, the most prominent of which indicates whether the first‐guess departures of a given observation type pull the model state into the direction of the verifying data (when processed with the ensemble estimated model error covariances). Alternatively, this can be regarded as cross‐validation between model error covariance estimates from the ensemble (which are used in the data assimilation system) and estimates diagnosed directly from the observations. A statistical cross‐validation tool has been developed that includes an indicator of statistical significance as well as a normalization that makes the statistical comparison largely independent from the total number of data and the closeness of their collocation. We also present a version of these diagnostics related to single‐observation experiments that exploits the same consistency relations but is easier to compute. Diagnostics computed within the Deutscher Wetterdienst's localized ensemble transform Kalman filter (LETKF) are presented for various kinds of bins. Results from well‐established in‐situ measurements are taken as a benchmark for more complex observations. Good agreement is found for radio‐occultation bending angle measurements, whereas atmospheric motion vectors are generally also beneficial but substantially less optimal than the corresponding in‐situ measurements. This is consistent with reported atmospheric motion vector height assignment problems. To illustrate its potential, a recent example is given where the method allowed identifying bias problems of a subgroup of aircraft measurements.Another diagnostic relationship compares the information content of the analysis increments with a theoretical optimum. From this, the information content of the LETKF increments is found to be considerably lower than those of the deterministic hybrid ensemble–variational system, which is consistent with the LETKF's limitation to the comparably low‐dimensional ensemble space for finding the optimal analysis.

Bioinspired Stretchable Fiber-Based Sensor toward Intelligent Human-Machine Interactions.

Wearable integrated sensing devices with flexible electronic elements exhibit enormous potential in human-machine interfaces (HMI), but they have limitations such as complex structures, poor waterproofness, and electromagnetic interference. Herein, inspired by the profile of Lindernia nummularifolia (LN), a bionic stretchable optical strain (BSOS) sensor composed of an LN-shaped optical fiber incorporated with a stretchable substrate is developed for intelligent HMI. Such a sensor enables large strain and bending angle measurements with temperature self-compensation by the intensity difference of two fiber Bragg gratings' (FBGs') center wavelength. Such configurations enable an excellent tensile strain range of up to 80%, moreover, leading to ultrasensitivity, durability (≥20,000 cycles), and waterproofness. The sensor is also capable of measuring different human activities and achieving HMI control, including immersive virtual reality, robot remote interactive control, and personal hands-free communication. Combined with the machine learning technique, gesture classification can be achieved using muscle activity signals captured from the BSOS sensor, which can be employed to obtain the motion intention of the prosthetic. These merits effectively indicate its potential as a solution for medical care HMI and show promise in smart medical and rehabilitation medicine.

Flexible and highly sensitive ionic skins with multiple dielectric layers for finger joint bending angle monitoring

Finger joint motion monitoring is crucial for rehabilitation training and ergonomics. Based on a multilayer dielectric structure, this study proposed flexible and highly sensitive ionic skins (sensors) for the measurement of the bending angles of finger joints. Each ionic skin, consisting silicon rubber films (multiple dielectric layers) and highly stretchable ionic conductors, was attached to the finger joint surface. The capacitance change of the skin was captured and used to measure finger joint bending angles. On this basis, the relationship between angles and capacitance variations was established. The relationship agreed with the experimental results. Furthermore, the effect of number of dielectric layers on sensitivity and linearity was discussed. The experimental results indicated that an increase in the number of dielectric layers improved sensitivity but suppressed linearity. The proposed ionic skins provided higher sensitivity and linearity than other flexible sensors. The five-layer ionic skin was four times more sensitive than existing ionic skins. The results confirmed that the multilayer dielectric structure of our ionic skins substantially enhanced the sensitivity for finger joint bending angle measurements.

A Multiscale-Based Approach to Understand Dendrite Deflection in Continuously Cast Steel Slab Samples

Dendrite bending angle measurements were conducted along two different directions on four steel slab samples collected from a conventional caster. The primary dendrites growing at the slab surface showed a transition in their growth direction as the distance from the surface increased. Numerical fluid flow simulation showed changes in the flow directions that might have caused the change in the growth direction. The bending angle measurements were also correlated with the casting process parameters. Thereafter, a multiscale approach was adopted to predict the dendrite deflection angles by correlating the macro-scale flow profile with the micro-scale bending angle formulation and subsequently corroborated with the industrial scale measurements.

A Stretchable Gold Nanowire Sensor and Its Characterization Using Machine Learning for Motion Tracking

Motion analysis techniques are well-known for quantitative and objective human skills evaluation in various applications, including sport and medical skills training and development procedures. Such analysis invariably requires reliable data acquisition and analytical tools that can effectively monitor the human body movements. This paper introduces a novel soft and stretchable strain sensor for joint angle measurement applications. The strain sensor is made of ultrathin gold nanowires, which is highly stretchable, and sensitive. However, the electrical response of the sensor involves nonlinearity and hysteresis. To tackle this problem, we propose to use a machine learning algorithm to characterise the sensor for enhancing the predictability of the sensing response. A sensor embedded hinge system is developed for automated measurement of bending angle to validate the characteristics of the developed sensing system. The sensor has a high gauge factor of about 12 and shows high durability during a repeated stress-and-release test. It could measure the bending motion with an error of less than 2°. The developed sensor, combined with the proposed machine learning algorithm, can accurately monitor the bending motion. We believe that our sensing technology has great potential to be used for the evaluation and improvement of human skills proficiency.

Flexible nanosensors for non-invasive creatinine detection based on triboelectric nanogenerator and enzymatic reaction

A creatinine nanosensor has been developed by PANI (polyaniline) and PDMS (polydimethylsiloxane). The mechanism is attributed to the coupling of the triboelectric nanogenerator (TENG) and the creatinine enzymatic reaction. After enzymatic modification, the triboelectric output from PANI and PDMS carries the information of the ambient creatinine concentration, which is due to the change of PANI electroconductivity in the enzymatic reactions. The nanosensors demonstrate high sensitivity at room temperature. The response reaches 51.42 % when creatinine concentration is 10−3 mol/L. Meanwhile, its good selectivity to creatinine is demonstrated compared with NaCl, glucose, and urea. The nanosensor also supports large flexibility in bending angle measurements (10°–40°), thereby potentially allowing creatinine detection in wearable sensing applications. Experimental results show that the flexible nanosensor can offer continuous and non-invasive detection of creatinine, paving the way for electronic skin and self-powered healthcare systems.

Integration and Testing of a Three-Axis Accelerometer in a Woven E-Textile Sleeve for Wearable Movement Monitoring.

This paper presents a method to integrate and package an accelerometer within a textile to create an electronic textile (e-textile). The smallest commercially available accelerometer sensor (2 mm × 2 mm × 0.95 mm) is used in the e-textile and is fully integrated within the weave structure of the fabric itself, rendering it invisible to the wearer. The e-textile forms the basis of a wearable woven sleeve which is applied to arm and knee joint bending angle measurement. The integrated e-textile based accelerometer sensor system is used to identify activity type, such as walking or running, and count the total number of steps taken. Performance was verified by comparing measurements of specific elbow joint angles over the range of 0° to 180° with those obtained from a commercial bending sensor from Bend Labs and from a custom-built goniometer. The joint bending angles, measured by all three sensors, show good agreement with an error of less than ~1% of reading which provides a high degree of confidence in the e-textile sensor system. Subsequently, knee joint angles were measured experimentally on three subjects with each being tested three times on each of three activities (walking, running and climbing stairs). This allowed the minimum and maximum knee joint angles for each activity to be determined. This data is then used to identify activity type and perform step counting.

Evaluation of Ionospheric Scintillation in GNSS Radio Occultation Measurements and Simulations

AbstractLike any other system relying on transionospheric propagation, Global Navigation Satellite System (GNSS) Radio Occultation (GNSS‐RO) is affected by ionospheric conditions during measurements. Regions of plasma irregularities in F region create abrupt gradients in the distribution of ionized particles. Radio signals propagated through such regions suffer from constructive and destructive contributions in phase and amplitude, known as scintillations. Different approaches have been proposed in order to model and reproduce the wave propagation through ionospheric irregularities. We present simulations considering single‐slope power law model of irregularities integrated with Multiple Phase Screen (MPS) propagation. In this work, the capability of the scintillation model to reproduce features in low‐latitude MetOp measurements in the early hours of DOY 76, 2015 is evaluated. Power spectral density (PSD) analysis, scintillation index, decorrelation time, and standard deviation of neutral bending angle are considered in the comparison between the simulations and RO measurements. The results demonstrate the capability of the simulator to replicate an equivalent error contribution to the neutral bending angle measurement in cases of moderate to strong scintillation.

Estimation of temperature-dependent yield strength and modulus of elasticity during laser bending

In this work, an inverse method is developed to estimate the temperature-dependent value of yield strength (Y) and modulus of elasticity (E) of the material during a laser bending process. The method requires measurement of bend angle of the laser scanned workpiece. The inverse model uses the bend angle computed by a direct model. The temperature-dependent Y and E are inversely estimated by minimizing the difference between actual and direct model predicted bend angles. The validation of the proposed method is demonstrated with the help of two examples. For this purpose, inversely estimated values of E and Y are used to predict bend angles for various processing conditions and predicted values are compared with actual values. In examples, actual data has been obtained from a detailed FEM simulation in lieu of shop floor experiments. Later on, the proposed method is also validated by performing shop floor experiments for AH36 steel.

A cost-effective device for online measurement of sheet metal bending angle on CNC press brakes based on capacitive sensors

Sheet metal bending on press brakes is one of the most widespread manufacturing processes. A common issue in press brake bending is the deviation of the actual bending angle from the theoretical one due to elastic spring-back of the sheet metal. This is typically rectified by a systematic trial-and-error process, which has to be based on a suitable measuring device that is flexible enough to adapt to a wide range of computer numerically controlled machines, accurate enough with respect to modern manufacturing needs and cost effective enough to be used on low cost press brakes. This work presents the development of such a device resembling a miniature robotic arm and employing capacitive sensors. Two stepping motors adapt the arm to any bending angle sheet configuration. The measuring process is commanded by a microcontroller. Statistical evidence on accuracy and repeatability of the system is provided, being better than 0.1° and 0.3° whilst cost is kept reasonable.

A cost-effective device for online measurement of sheet metal bending angle on CNC press brakes based on capacitive sensors

A cost-effective device for online measurement of sheet metal bending angle on CNC press brakes based on capacitive sensors