Ground Position Research Articles

Analyzing Volcanic, Tectonic, and Environmental Influences on the Seismic Velocity from 25 Years of Data at Mount St. Helens

Abstract We estimate changes in the seismic velocity (dv/v) from 25 years of ambient seismic noise recorded at Mount St. Helens (MSH). At MSH, the availability of seismic stations changes frequently due to station failure and the installation of new stations. Therefore, it is difficult to combine relative measurements that do not span the same time and space. We tackle this challenge by developing a spatial imaging algorithm to normalize all ∼1400 dv/v time series onto one spatial grid. Thereby, we obtain time-dependent velocity change maps of the MSH region, which we analyze with the help of auxiliary observations, such as ground position (i.e., Global Navigation Satellite System [GNSS]), weather data, environmental observations, and regional seismicity. In the dv/v time series, we find a variety of dynamics caused by volcanic, tectonic, and environmental forcing. With the initiation of MSH’s 2004–2008 volcanic crisis, dv/v exhibits a significant increase, which we link to the deflation of the volcanic plumbing system, also observed on GNSS data. Between 2013 and 2018, when seismicity levels are elevated, we find lower velocities at depth. This phase is followed by an episode of relative quiescence, accompanied by significant dv/v increases close to the St. Helens seismic zone. We suggest a reinflation of the magmatic plumbing system after MSH’s 2004–2008 eruption lasting until about 2017. Afterward, the magmatic activity in the subsurface reduces, thereby decreasing pressure and increasing the seismic velocity. Fluctuating groundwater levels may dominate the seasonal cycles in the dv/v time series. A contrasting seasonal response between the high-elevation edifice and foothill valleys may indicate that surface freezing inhibits subsurface groundwater infiltration at higher altitudes.

An Automated Approach for Mapping Mining-Induced Fissures Using CNNs and UAS Photogrammetry

Understanding the distribution and development patterns of mining-induced fissures is crucial for environmental protection and geological hazard prevention. To address labor-intensive manual inspection, an automated approach leveraging Convolutional Neural Networks (CNNs) and Unmanned Aerial System Photogrammetry (UASP) is proposed for fissure identification and mapping. Initially, the ResNet-50 network was employed for the binary classification of the cropped UASP orthophoto images. A comparative analysis was conducted to determine the optimal model between DeepLabv3+ and U-Net. Subsequently, the identified fissures were mosaicked and spatially projected onto the original orthophoto image, incorporating precise projection data, thereby furnishing a spatial reference for environmental governance. The results indicate a classification accuracy of 93% for the ResNet-50 model, with the U-Net model demonstrating a superior identification performance. Fissure orientation and distribution patterns are influenced by the mining direction, ground position of the mining workface, and topographic undulations. Enhancing the CNN performance can be achieved by incorporating variables such as slope indices, vegetation density, and mining workface locations. Lastly, a remote unmanned approach is proposed for the automated mapping of mining-induced fissures, integrated with UAS automated charging station technology. This study contributes to the advancement of intelligent, labor-saving, and unmanned management approaches advocated by the mining industry, with potential for broad applications in mining environmental protection efforts.

Artificial ground reflector size and position effects on energy yield and economics of single‐axis‐tracked bifacial photovoltaics

AbstractArtificial ground reflectors improve bifacial energy yield by increasing both front and rear‐incident irradiance. Studies have demonstrated an increase in energy yield due to the addition of artificial reflectors; however, they have not addressed the effect of varying reflector dimensions and placement on system performance and the impact of these parameters on the reflectors' financial viability. We studied the effect of high albedo (70% reflective) artificial reflectors on single‐axis‐tracked bifacial photovoltaic systems through ray‐trace modeling and field measurements. In the field, we tested a range of reflector configurations by varying reflector size and placement and demonstrated that reflectors increased daily energy yield up to 6.2% relative to natural albedo for PERC modules. To confirm the accuracy of our model, we compared modeled and measured power and found a root mean square error (RMSE) of 5.4% on an hourly basis. We modeled a typical meteorological year in Golden, Colorado, to demonstrate the effects of artificial reflectors under a wide range of operating conditions. Seventy percent reflective material can increase total incident irradiance by 1.9%–8.6% and total energy yield by 0.9%–4.5% annually after clipping is considered with a DC–AC ratio of 1.2. Clipping has a significant effect on reflector impact and must be included when assessing reflector viability because it reduces reflector energy gain. We calculated a maximum viable cost for these improvements of up to $2.50–4.60/m2, including both material and installation, in Golden. We expanded our analysis to cover a latitude range of 32–48°N and demonstrated that higher‐latitude installations with lower energy yield and higher diffuse irradiance content can support higher reflector costs. In both modeling and field tests, and for all locations, the ideal placement of the reflectors was found to be directly underneath the module due to the optimized rear irradiance increase.

Multi-point synchronous temporary grounding wire detection device based on convolutional neural networks

To prevent grounding accidents caused by forgetting to remove the temporary grounding wires and the contact of trees with the distribution network, a multi-point synchronous temporary grounding wire detection device based on convolutional neural networks is developed. The developed device can judge the type of groundings on the test line quickly and locate the ground points accurately during the cut-out. Three-phase alternating current (AC) signals with a specific frequency are injected at multiple points on the line by multiple groups of the device controlled by Raspberry Pi 3B + and embedded Android. The device can achieve the approximate location through the impedance ranging method and the accurate location by integrating the data from multiple points. The trained EfficientNet-B0 algorithm is utilized to predict the grounding positions. The tested results of the prototype verify the accuracy and rapidity of grounding diagnosis and positioning.

Динаміка показників техніко-тактичної підготовленості дзюдоїстів 19-21 років середніх вагових категорій під впливом запропонованих моделей підготовки

Purpose: to investigate the dynamics of indicators of technical and tactical preparedness of judokas of 19-21 years old of middle weight categories under the influence of the offered models of training. Material and methods. Methods of the research: analysis and generalization of scientific and methodical literature; timekeeping; analysis of protocols and video recordings of fights of judokas of 19-21 years old of weight categories up to 60 kg, up to 66 kg; pedagogical experiment; methods of mathematical statistics. The pedagogical experiment was attended by 20 judokas aged 19-21 years (Candidate for Master of Sports, Master of Sports of Ukraine), who were divided into control and experimental groups of 10 athletes each. We analyzed 60 fights of sportsmen of the experimental and 60 fights of the control groups. Results: after the pedagogical experiment, the number of fights that ended early increased in the judokas of the experimental group (the beginning of the experiment - 66 %, the end - 77 %) and the number of fights within the allotted time and in additional time decreased. This suggests that the fights of the athletes of the experimental group are quite dynamic, and the use of combinations and counterattacks allows to finish the fight before the allotted time. Also, the number of counterattacks and combinations of techniques during fights increased statistically significantly. Thus, the number of application of the combination technique increased from 18 to 23 (t=3,61; p<0,05), and the counterattacking from 21 to 31 (t=5,73; p<0,05). Also, the increase in the total number of real attempts to perform technical actions from 104 to 138 was established. A more detailed analysis showed that in the stand position sportsmen of the experimental group performed a smaller number of real attempts to perform technical actions in comparison with the beginning of the experiment (beginning - 103, the end - 97). Also, there is an increase in the effectiveness of technical actions (beginning - 24 (23 %), end - 35 (36 %)) estimated by judges as a half-victory (beginning - 12, end - 20) and as a pure victory (beginning - 12, end - 15). In the ground position, an increase in the number of real technical actions is observed. Thus, at the beginning of the experiment this indicator was 30 attempts, at the end - 38. Due to this the total number of real attempts of technical actions increased. Also, there is an increase in the effectiveness of technical actions (beginning - 14 (47 %), end - 19 (50 %)) evaluated by judges as half a victory (beginning - 5, end - 8) and as a pure victory (beginning - 9, end - 11). Conclusions. It is established that under the influence of the offered models of technical and tactical preparation the use of combinations and counterattacks during a fight which allows to finish it earlier than the allotted time in sportsmen of the experimental group increased. The increase in the total number of real attempts to perform technical actions, as well as certain actions (throw with the emphasis of the lower leg in the thigh, picking up under one leg, turning with hands), their effectiveness was established. Also, there is a decrease in the number of throws from the knees in a fight and an increase in its effectiveness. Keywords: competitive activity, judo, training, weight categories, indicators, modeling, models.

Real-Time AI-Assisted Push-Broom Hyperspectral System for Precision Agriculture.

In the ever-evolving landscape of modern agriculture, the integration of advanced technologies has become indispensable for optimizing crop management and ensuring sustainable food production. This paper presents the development and implementation of a real-time AI-assisted push-broom hyperspectral system for plant identification. The push-broom hyperspectral technique, coupled with artificial intelligence, offers unprecedented detail and accuracy in crop monitoring. This paper details the design and construction of the spectrometer, including optical assembly and system integration. The real-time acquisition and classification system, utilizing an embedded computing solution, is also described. The calibration and resolution analysis demonstrates the accuracy of the system in capturing spectral data. As a test, the system was applied to the classification of plant leaves. The AI algorithm based on neural networks allows for the continuous analysis of hyperspectral data relative up to 720 ground positions at 50 fps.

Defending Democracy Against Populist Neo-Fascist Attacks: The Role and Problems of Public Sphere Theory

In the wake of the recent attacks on democracy by a re-invigorated populist neo-fascism there is a pressing need to articulate a middle ground position in debates between the public sphere paradigm and its critiques. This requires an engagement with tensions between consensus and conflict, rationality and emotion, and the system and the lifeworld. Furthermore, there is also a need to scrutinize the role of hybrid media system in promoting populist neo-fascist discourses and actors, but also assert its normative task to combat it. Whereas conflict and power cannot be eradicated from the political, conflict is also a destructive force which requires a set of agreed upon ethico-political principles in order for a radical democracy to function. It is also argued that emotions need to be part of the democratic fight-back, but it is also suggested that a critical realist disposition combining epistemic relativism with judgmental rationality will be crucial to counter the relativism on steroids practiced by neo-fascist actors. Finally, the hybrid media system needs to be reconnected with the lifeworld, citizen interests and democratic values through a new regulatory framework, and the tradition of public journalism could provide inspiration for a democratic fightback from within the media system.

Performance of wrestlers at the Olympic Games: gender aspect

Background and Study Aim. With the increasing popularity of freestyle wrestling, the scientific community is paying more attention to gender factors that may influence the performance and success of competitive activities.
 The aim of study to determine differences in performance indicators between male and female wrestlers in the Olympic Games 2021.
 Material and Methods. The study included 192 athletes, consisting of 96 male wrestlers and 96 female wrestlers. An analysis of match records and video footage was conducted for women's (n=113) and freestyle (n=114) wrestling at the 2021 Tokyo Olympic Games. The assessment of performance indicators utilized an expert evaluation method. Statistical analysis of the obtained data was carried out using licensed Excel spreadsheet software. For categorical data, results were expressed in absolute numbers and percentages.
 Results. Based on the analysis of competitive activities at the 2021 Olympic Games, 12 primary technical-tactical actions were identified. The most frequently employed actions were in the standing position: leg attacks, with male wrestlers performing it 35.8% of the time and female wrestlers 30.3%; in the ground position, male wrestlers employed gut wrench (7.6%), while female wrestlers used ankle lace (9.4%). It was found that male wrestlers and female wrestlers accumulated approximately the same number of points for their actions: male wrestlers (926 points) and female wrestlers (912 points). The effectiveness in the standing position was higher for male wrestlers (720 points) than for female wrestlers (621 points). In the ground positions, female wrestlers demonstrated better effectiveness (291 points) than male wrestlers (206 points). The number of points deducted for rule violations was significantly lower for female wrestlers (8 times) compared to male wrestlers (27 times). Time stoppages during challenge reviews were fewer for female wrestlers (7 times) compared to male wrestlers (18 times).
 Conclusions. The conducted research indicates differences in the performance indicators of freestyle wrestling between men and women. Male wrestlers employ more actions in the standing position (81.7%) than female wrestlers (70.7%). Correspondingly, female wrestlers execute more actions in the ground positions (29.3%) compared to male wrestlers (18.3%). The total number of actions performed is higher for male wrestlers (579) than for female wrestlers (518). Female wrestlers achieve more premature victories (32.7% of all matches) compared to male wrestlers (24.6%). The obtained results will assist coaches in better adapting to gender differences and developing specific training programs for athletes.

An Overview of Grounding Design and Grounding Fault Detection and Location Methods for a Multiphase Rectifier Generator Power Supply System

A multiphase rectifier generator is important power generation equipment in DC power systems in transportation fields such as ships and aviation. Grounding design and grounding fault detection and positioning are key technologies for the safe operation of the power system. This article aims to systematically elaborate on the current research status of its related content. Firstly, the topological structure characteristics of the multiphase rectifier generator power supply system are introduced, the advantages and disadvantages of different grounding methods, position selection, and other design schemes are analyzed, and reasonable suggestions are given for the selection of grounding resistance. Secondly, a brief introduction is given to the research progress on ground fault detection and location in the medium voltage DC integrated power systems of ships, and the characteristics of typical methods for ground fault detection and location in DC power grid systems are summarized. Finally, the future research directions are outlined.

Renegotiating the Islam and Development-Nexus in Indonesia: Fikih Peradaban as a Middle Ground between Local and Global Development Paradigms

I n 2015, the United Nations introduced the that aims at globally achieving concrete Sustainable Development Goals (SDGs). Today, sustainable development has become the dominant development narrative in 2030 Agenda, a new development paradigm international cooperation discourse, despite criticism of its top-down approach and secular bias. This explorative article discusses the potential of Indonesian Islamic concepts, such as Nahdlatul Ulama’s Islam Nusantara and Fikih Peradaban, to contribute to the sustainable development discourse from an Islamic perspective. By mapping the current intellectual debate on Fikih Peradaban, I demonstrate that Fikih Peradaban is a particularly suited approach as epistemologically and conceptually it occupies a middle ground position that mediates between local and global development paradigms. I further argue that Fikih Peradaban’s focus on the concepts of humanism, humanist Islam (or Islamic humanism), and Islamic legal reasoning in the service of all people regardless of religious affiliation may contribute to its global appeal and effectiveness. The article draws on notes taken at a conference on “Islam Nusantara and World Peace” (February 5, 2023) in Surabaya as well as notes taken at the first Fikih Peradaban conference (February 6, 2023) in Surabaya. It is also based on a close reading of official material that accompanied the latter conference. Furthermore, I embed the discussion on the nexus between Indonesian Islamic concepts and sustainable development into the broader academic and policy debate on the role of religion within sustainable development. Hence, this article is connected to the research project “Freedom and Development? Religious Actors, Freedom of Religion and Belief, and Sustainable Development” conducted by the German Institute for Global and Area Studies, Hamburg, from 2020 to 2023.
 Keywords: Indonesia, Fikih Peradaban, humanist Islam, sustainable development

Simulation of Foreign Object Detection Using Passive Inductive Sensors in a Wireless Charging System for Electric Vehicles

During wireless charging of the traction battery of electrically powered vehicles, the active area between the ground and vehicle assemblies must be monitored for inductive power transfer. If metallic foreign objects enter this area, they interact with the magnetic field and can heat up strongly, and thus become a potential source of hazard. To detect such foreign objects, measurements based on passive inductive sensors have already been carried out in advance. However, a large number of factors influence the detectability of metallic foreign objects, such as the characteristics of the magnetic field of the ground assembly coil, the size, shape, position, orientation, and material composition of the foreign objects, or the design of the sensor coils. The related practical testing effort can be reduced if the characteristics of the charging system and the foreign object detection system can be simulated. Therefore, simulation models were developed within the scope of this work and validated with the help of practical measurements. These models were used in the next step to analyze new test arrangements that had not yet been investigated by measurement. In the simulations described here, precision in the range of 1 mV could be achieved. Cumulatively, many influencing factors can be easily investigated, and results can be generated in a largely automated manner and typically in a wider variety than with practical measurements.

Electromagnetic disturbance characteristic of typical high voltage switchgear interruption process in offshore wind farm based on integrated conduction model

AbstractIn an offshore wind farm, a high‐voltage switchgear interruption in an offshore substation creates a high‐frequency, high‐amplitude overvoltage that can cause severe electromagnetic interference problems in the intelligent electronic device. To address this issue, mathematical models, vector fitting and finite element method were used to build an integrated electromagnetic disturbance conduction model, whose accuracy was verified by large current interruption tests. Through the simulation of a typical offshore wind farm's single‐phase grounding fault interruption process, the electromagnetic disturbance characteristics and the impact of the ground position are obtained. The results show that during the fault interruption process of phase B grounded, the dominant frequency of disturbance voltage can reach 4.34 MHz, and the amplitude can reach 1.12 kV. The ground grid has a large impact on the interference voltage, which can reach a maximum value of 2.28 kV under specific conditions. The disturbance voltage in the fault process mainly comes through the current transformer, while during the interruption process, it mainly comes through the ground grid. The authors provide a method to establish the integrated electromagnetic disturbance simulation model, which can improve the accuracy of the electromagnetic disturbance conduction process simulation of intelligent components.

Grounding line positions of Amery Ice Shelf based on long interferometric Sentinel-1 time series

Grounding line positions of Amery Ice Shelf based on long interferometric Sentinel-1 time series

Flight Test Analysis of UTM Conflict Detection Based on a Network Remote ID Using a Random Forest Algorithm

In an area where unmanned aerial system (UAS) traffic is high, a conflict detection system is one of the important components for the safety of UAS operations. A novel UAS traffic management (UTM) monitoring application was developed, including a conflict detection system using the inverted teardrop area detection based on real-time flight data transmitted from the network remote identification (Remote ID) modules. This research aimed to analyze the performance of the UTM-monitoring application based on flight test data using statistical and machine learning approaches. The flight tests were conducted using several types of small fixed-wing unmanned aerial vehicles (UAVs) controlled by a human pilot using a Taiwan cellular communication network in suburban and rural areas. Two types of scenarios that involved a stationary, on-the-ground intruder and a flying intruder were used to simulate a conflict event. Besides the statistical method calculating the mean and standard deviation, the random forest algorithm, including regressor and classifier modules, was used to analyze the flight parameters and timing parameters of the flight tests. The result indicates that the processing time of the UTM application was the most significant parameter to the conflict warning parameter, besides the relative distance and height between UAVs. In addition, the latency time was higher for the flight in the rural area than the suburban area and also higher for data transmitted from the flying position than the ground position. The findings of our study can be used as a reference for aviation authorities and other stakeholders in the development of future UTM systems.

Minaret Shape Micro-Strip Patch Antenna with Partial Ground Plane for Lower 5G and Wi-Max Applications

Antennas are a difficult component to design, yet they play critical functions in wireless transmission systems. To construct the required antenna, the antenna designer must overcome enormous challenges in getting all of the antenna's optimal qualities. Antenna designers must consider antenna factors like bandwidth, return loss, VSWR, gain, directivity, efficiency, and so on, for specific applications. So keep all parameter values as optimal as possible; sometimes you may need to adjust the design of the antenna from its standard shape. The present investigation describes the development of a partial ground-plane micro-strip patch antenna in the shape of a minaret for use in lower 5G and Wi-MAX networks. A microstrip patch antenna with a minaret-shaped radiating element and a partial ground plane is suggested. The suggested antenna is simple because it does not include any unwanted components on the patch, yet the significant gain is maintained by optimizing the ground plane's dimensions and position. The proposed antenna is constructed using a Rogers RT5880 (lossy) substrate, the line feeding method, and 0.035 mm thick (annealed) copper for the patch and ground components. CST Studio Suite 2018 is used for layout and modelling. The antenna is 28 x 16 x 0.79 mm3 and offers a maximum gain of 2.321 dB and a maximum directivity of 2.529 dBi. The recommended antenna has a frequency range of 3.3721 GHz to 4.2382 GHz, making it usable for both low-band 5G and Wi-MAX systems.

항공사 지상직원이 지각한 고객무례행동이 직무성과에 미치는 영향: 동료지원의 조절효과와 직무스트레스의 매개효과를 중심으로

This study aimed to verify the mediating effect of job stress to explain the mechanism of customer incivility perceived by airline ground staffs on job performance. In addition, the role of coworker support among social support was verified as a variable that can control the effect of job stress on job performance. In order to verify the research model, a survey was conducted on 235 people working in airline ground positions. As a result of the study, first, the influence relationship of customer incivility on mental stress was significant as a positive (+) relationship. In addition, the influence relationship of customer incivility on physical stress was significant as a positive (+) relationship. Second, the influence relationship of mental stress on job performance was not significant. In addition, the influence relationship of physical stress on job performance was not significant. Third, as a result of verifying the moderating effect of coworker support, it was confirmed that there was a difference in influence depending on the difference in the high and low involvement of coworker support.

Suitability mapping of solid waste disposal sites in Obio/Akpor local government area: rivers state of Nigeria

Obio/Akpor Local Government Area of Rivers State have constantly witnessed Rapid City growth and increased urbanization due to persistence rural-urban migration and the quest for human to meet their needs and wants. This has increased solid waste generation and unregulated dumping of solid wastes in unapproved sites. This prompted the need for this study which is aimed at mapping the suitability of solid waste sites in the study area with the objective of identifying the spatial locations and development of a database of suitability or otherwise of solid waste disposal sites. Ground survey and Geospatial techniques were utilized for data acquisition, manipulation and processing. Garmin 78csx GNSS receiver was used in observing the coordinates of ground positions of all solid waste disposal sites in the study area, the obtain coordinates were charted on the Google earth imagery (2022) and Open Street Map (OSM) (2022) to ensure the positions falls within the shape-file of the study area, On-Screen vectorization was perform using the point, line and polygon spatial tools in the QGIS 3.22 bialowieza software environment to determine the position and extent of solid waste sites under study. Proximity analysis was performed in QGIS environment for buffer of 200m, 500m and 1km to ascertain the suitability of solid waste collection centers and dumpsites base on global standard and proximity maps were produced. A total of (114) solid waste disposal sites were mapped, with (27) legal and (73) illegal collection points and (2) suitable and (12) unsuitable dumpsites respectively. The study also revealed that Elelenwo community in ward 6 has the highest (12) whereas Egbelu Ozodo community in ward 16 has the lowest (1) number of collection sites in the study area. Immediate review and enforcement of solid waste disposal and management laws is needed to forestall likely environmental hazards resulting from indiscriminate dumping of refuse in the study area.

Modelling Australian Rules Football as spatial systems with pairwise comparisons

Abstract Statistical analysis in competitive sport is an important tool for developing strategy and seeking competitive advantages. However, for complex team sports such as Australian Rules Football, major limitations occur when using possession event data for game analysis. First, focusing on counting possession events does not capture the impact of off-the-ball actions such as ground positioning of other players. Second, it is difficult to determine the extent that an event is due to either team’s relative proficiency or skill. Third, there is limited possession event data available from each match and modelling efforts often have low statistical power. Here we reinterpret event data into positional systems and utilise pairwise performance metrics to understand the relative team proficiency in each of these states. These metrics can then be used to construct transition probabilities between states for future games, and ultimately, absorbing probabilities of goal states. Our approach effectively predicts match outcomes using team ratings for forward, midfield and defensive systems and is sufficiently interpretable to support strategic decision-making by coaching departments in the Australian Football League (AFL).

3D cloud envelope and cloud development velocity from simulated CLOUD (C3IEL) stereo images

Abstract. A method to derive the 3D cloud envelope and the cloud development velocity from high spatial and temporal resolution satellite imagery is presented. The CLOUD instrument of the recently proposed C3IEL mission lends itself well to observing at high spatial and temporal resolutions the development of convective cells. Space-borne visible cameras simultaneously image, under multiple view angles, the same surface domain every 20 s over a time interval of 200 s. In this paper, we present a method for retrieving cloud development velocity from simulated multi-angular, high-resolution top of the atmosphere (TOA) radiance cloud fields. The latter are obtained via the image renderer Mitsuba for a cumulus case generated via the atmospheric research model SAM and via the radiative transfer model 3DMCPOL, coupled with the outputs of an orbit, attitude, and camera simulator for a deep convective cloud case generated via the atmospheric research model Meso-NH. Matching cloud features are found between simulations via block matching. Image coordinates of tie points are mapped to spatial coordinates via 3D stereo reconstruction of the external cloud envelope for each acquisition. The accuracy of the retrieval of cloud topography is quantified in terms of RMSE and bias that are, respectively, less than 25 and 5 m for the horizontal components and less than 40 and 25 m for the vertical components. The inter-acquisition 3D velocity is then derived for each pair of tie points separated by 20 s. An independent method based on minimising the RMSE for a continuous horizontal shift of the cloud top, issued from the atmospheric research model, allows for the obtainment of a ground estimate of the velocity from two consecutive acquisitions. The mean values of the distributions of the stereo and ground velocities exhibit small biases. The width of the distributions is significantly different, with higher a distribution width for the stereo-retrieved velocity. An alternative way to derive an average velocity over 200 s, which relies on tracking clusters of points via image feature matching over several acquisitions, was also implemented and tested. For each cluster of points, mean stereo and ground positions were derived every 20 s over 200 s. The mean stereo and ground velocities, obtained as the slope of the line of best fit to the mean positions, are in good agreement.

Data-Driven Variable Impedance Control of a Powered Knee-Ankle Prosthesis for Sit, Stand, and Walk with Minimal Tuning.

Although the average healthy adult transitions from sit to stand over 60 times per day, most research on powered prosthesis control has only focused on walking. In this paper, we present a data-driven controller that enables sitting, standing, and walking with minimal tuning. Our controller comprises two high level modes of sit/stand and walking, and we develop heuristic biomechanical rules to control transitions. We use a phase variable based on the user's thigh angle to parameterize both walking and sit/stand motions, and use variable impedance control during ground contact and position control during swing. We extend previous work on data-driven optimization of continuous impedance parameter functions to design the sit/stand control mode using able-bodied data. Experiments with a powered knee-ankle prosthesis used by a participant with above-knee amputation demonstrate promise in clinical outcomes, as well as trade-offs between our minimal-tuning approach and accommodation of user preferences. Specifically, our controller enabled the participant to complete the sit/stand task 20% faster and reduced average asymmetry by half compared to his everyday passive prosthesis. The controller also facilitated a timed up and go test involving sitting, standing, walking, and turning, with only a mild (10%) decrease in speed compared to the everyday prosthesis. Our sit/stand/walk controller enables multiple activities of daily life with minimal tuning and mode switching.