Balance Control Strategy Research Articles

Human foot force informs balance control strategies when standing on a narrow beam.

Despite the abundance of studies on the control of standing balance, insights about the roles of biomechanics and neural control have been limited. Previous work introduced an analysis combining the direction and orientation of foot-ground forces. The "intersection point" of the lines of actions of these forces exhibited a consistent pattern across healthy, young subjects when computed for different frequency components of the center of pressure signal. To investigate the control strategy of quiet stance, we applied this intersection point analysis to experimental data of 15 healthy, young subjects balancing in tandem stance on a narrow beam and on the ground. Data from the sagittal and frontal planes were analyzed separately. The task was modeled as a double-inverted pendulum controlled by an optimal controller with torque-actuated ankle and hip joints and additive white noise. To test our prediction that the controller that minimized overall joint effort would yield the best fit across the tested conditions and planes of analyses, experimental results were compared with simulation outcomes. The controller that minimized overall effort produced the best fit in both balance conditions and planes of analyses. For some conditions, the relative penalty on the hip and ankle joints varied in a way relevant to the balance condition or to the plane of analysis. These results suggest that unimpaired quiet balance in a challenging environment can be best described by a controller that maintains minimal effort through the adjustment of relative ankle and hip joint torques. NEW & NOTEWORTHY This study explored balance control in humans during a challenging task using the novel intersection point analysis, based on foot-ground force direction and point of application. Experimental data of subjects standing on a narrow beam in tandem stance were compared with modeling results of a double-inverted pendulum. The analysis showed that individuals minimized effort by adjusting ankle and hip torques, shedding light on the interplay of biomechanics and neural control in maintaining balance.

Measurement report: Characteristics of airborne black-carbon-containing particles during the 2021 summer COVID-19 lockdown in a typical Yangtze River Delta city, China

Abstract. Black-carbon-containing (BCc) particles are ubiquitous in ambient air, significantly contributing to particulate matter (PM) pollution. The unexpected outbreak of the COVID-19 pandemic in the summer of 2021 prompted a localized and prolonged lockdown in Yangzhou, situated in the Yangtze River Delta, China. This lockdown led to significant alteration of local anthropogenic emissions, while neighboring cities continued regular operations, providing a unique opportunity for the investigation of BCc particle characteristics influenced by varying emission conditions. Single-particle aerosol mass spectrometer (SPA-MS) analysis revealed a notable decrease in the proportion of freshly emitted BCc particles during the lockdown (LD) period. However, PM2.5 concentrations remained relatively unchanged, with an observed increase in the proportion of aged BCc particles during LD compared to the period before the lockdown (BLD). The study also underscores the significant role of regional transport in PM2.5 pollution during the campaign. Moreover, reactive trace gases (e.g., NOx, SO2, and volatile organic compounds – VOCs) could form thick coatings on pre-existing particles, likely via enhanced heterogeneous hydrolysis under high relative humidity (RH), resulting in significant BCc particle growth (∼ 600 nm), as well as PM2.5 concentration, during LD. Our study highlights that short-term, strict local emission controls may not effectively reduce PM pollution due to the complex production and transmission characteristics of BCc particles and the nonlinear responses of PM2.5 to its precursors. Achieving further effective PM2.5 reduction mandates a focus on nuanced control of BCc particles and necessitates a comprehensive and extensive approach with a regionally coordinated and balanced control strategy through joint regulation.

Walking balance control in different settings: Effects of walking speed and biological sex

BackgroundPrevious research has suggested that spatiotemporal step parameters differ between settings; however, it remains unclear how different settings influence walking balance control. Research questionHow do settings and sex influence walking balance control during walking at different speeds for young adults? MethodsForty-two adults (21 male (23 ± 4 years), 21 female (24 ± 5 years)) completed overground walking trials in four settings: laboratory (10 m), hallway, indoor open, and outdoor pathway (all 20 m) at three self-selected speeds (slow, preferred, fast) following verbal instructions. Participants wore 17 inertial sensors (Xsens Awinda, Movella, Henderson, NV) to capture total body kinematics. The number of included strides was matched across all conditions, with six strides included in each condition for all participants. Medial-lateral and anterior-posterior total body angular momentum range over each stride was calculated (HML range and HAP range). Setting × speed × sex mixed factorial analysis of variance with repeated measures on setting and speed were used for statistical analysis (α =.05). ResultsSignificant setting × speed interactions (p <.001) were present for both outcomes. HML range was greater in the laboratory and hallway compared to the indoor open and outdoor pathway settings for slow walking speed only. HAP range was lower in the outdoor pathway compared to all indoor settings at slow and preferred walking speeds. Differences in HAP range between settings was more pronounced at the slow speed condition. Across setting and speed conditions, HML range was greater for males compared to females. SignificanceYoung adults may alter their balance control strategy depending on the setting (laboratory, indoor open and outdoor pathway), particularly at slow speeds. Researchers and clinicians are cautioned not to assume walking in laboratory settings reflects walking in all settings nor that males and females can be examined as a single group.

A Fast State-of-Charge (SOC) Balancing and Current Sharing Control Strategy for Distributed Energy Storage Units in a DC Microgrid

In isolated operation, DC microgrids require multiple distributed energy storage units (DESUs) to accommodate the variability of distributed generation (DG). The traditional control strategy has the problem of uneven allocation of load current when the line impedance is not matched. As the state-of-charge (SOC) balancing proceeds, the SOC difference gradually decreases, leading to a gradual decrease in the balancing rate. Thus, an improved SOC droop control strategy is introduced in this paper, which uses a combination of power and exponential functions to improve the virtual impedance responsiveness to SOC changes and introduces an adaptive acceleration factor to improve the slow SOC balancing problem. We construct a sparse communication network to achieve information exchange between DESU neighboring units. A global optimization controller employing the consistency algorithm is designed to mitigate the impact of line impedance mismatch on SOC balancing and current allocation. This approach uses a single controller to restore DC bus voltage, effectively reducing control connections and alleviating the communication burden on the system. Lastly, a simulation model of the DC microgrid is developed using MATLAB/Simulink R2021b. The results confirm that the proposed control strategy achieves rapid SOC balancing and the precise allocation of load currents in various complex operational scenarios.

A control strategy considering buildings’ thermal characteristics to mitigate heat supply-demand mismatches in district heating systems

In district heating systems (DHS), periodic heat supply-demand mismatches (HSDM) exacerbate issues such as thermal imbalance and hydraulic instability. To mitigate these issues, this paper proposes a supply water temperature correction strategy for heating stations that considers building's thermal characteristics. Firstly, buildings are classified into energy-saving levels based on comprehensive thermal characteristic Bc and heat load index. Secondly, simulation models are developed for buildings with different thermal characteristics, and response of indoor temperature to supply-demand mismatch rates was analyzed. Then, after determining the regulation sequence and supply water temperature of heating stations, a balanced control strategy is formulated for HSDM conditions. Finally, the proposed strategy was applied to a practical combined heat and power system (CHPS) in severe cold regions. The results showed that the studied heating stations were classified into 4 types. After regulation of both insufficient and excessive heating conditions, the indoor temperature guarantee rate increased by over 20 %; the ranges of thermal imbalance degree and hydraulic imbalance degree were reduced by more than 0.09 and 0.22, respectively; the SD of supply water pressure and supply-return pressure difference were reduced by over 0.17 and 0.11, respectively. The strategy provides a reference for global balanced control of DHS under similar HSDM conditions.

Implementation of a fluid balance control strategy in critically ill patients: POINCARE-2 trial process evaluation

BackgroundPOINCARE-2 trial aimed to assess the effectiveness of a strategy designed to tackle fluid overload through daily weighing and subsequent administration of treatments in critically ill patients. Even in highly standardized care settings, such as intensive care units, effectiveness of such a complex intervention depends on its actual efficacy but also on the extent of its implementation. Using a process evaluation, we aimed to provide understanding of the implementation, context, and mechanisms of change of POINCARE-2 strategy during the trial, to gain insight on its effectiveness and inform the decision regarding the dissemination of the intervention.MethodsWe conducted a mixed-method process evaluation following the Medical Research Council guideline. Both quantitative data derived from the trial, and qualitative data from semi-structured interviews with professionals were used to explain implementation, mechanisms of change of the POINCARE-2 strategy, as well as contextual factors potentially influencing implementation of the strategy.ResultsScore of actual exposure to the strategy ranged from 29.1 to 68.2% during the control period, and from 61.9 to 92.3% during the intervention period, suggesting both potential contamination and suboptimal fidelity to the strategy. Lack of appropriate weighing devices, lack of human resources dedicated to research, pre-trial rooted prescription habits, and anticipated knowledge of the strategy have been identified as the main barriers to optimal implementation of the strategy in the trial context.ConclusionsBoth contamination and suboptimal fidelity to POINCARE-2 strategy raised concerns about a potential bias towards the null of intention-to-treat (ITT) analyses. However, optimal fidelity seemed reachable. Consequently, a clinical strategy should not be rejected solely on the basis of the negativity of ITT analyses’ results. Our findings showed that, even in highly standardized care conditions, the implementation of clinical strategies may be hindered by numerous contextual factors, which demonstrates the critical importance of assessing the viability of an intervention, prior to any evaluation of its effectiveness.Trial registrationNumber NCT02765009

Wearable accelerometers reveal objective assessment of walking symmetry and regularity in idiopathic scoliosis patients.

Scoliosis is a multifaceted three-dimensional deformity that significantly affects patients' balance function and walking process. While existing research primarily focuses on spatial and temporal parameters of walking and trunk/pelvic kinematics asymmetry, there remains controversy regarding the symmetry and regularity of bilateral lower limb gait. This study aims to investigate the symmetry and regularity of bilateral lower limb gait and examine the balance control strategy of the head during walking in patients with idiopathic scoliosis. The study involved 17 patients with idiopathic scoliosis of Lenke 1 and Lenke 5 classifications, along with 17 healthy subjects for comparison. Three-dimensional accelerometers were attached to the head and L5 spinous process of each participant, and three-dimensional motion acceleration signals were collected during a 10-meter walking test. Analysis of the collected acceleration signals involved calculating five variables related to the symmetry and regularity of walking: root mean square (RMS) of the acceleration signal, harmonic ratio (HR), step regularity, stride regularity, and gait symmetry. Our analysis reveals that, during the walking process, the three-dimensional motion acceleration signals acquired from the lumbar region of patients diagnosed with idiopathic scoliosis exhibit noteworthy disparities in the RMS of the vertical axis (RMS-VT) and the HR of the vertical axis (HR-VT) when compared to the corresponding values in the healthy control (RMS-VT: 1.6±0.41 vs. 3±0.47, P<0.05; HR-VT: 3±0.72 vs. 3.9±0.71, P<0.05). Additionally, the motion acceleration signals of the head in three-dimensional space, including the RMS in the anterior-posterior and vertical axis, the HR-VT, and the values of step regularity in both anterior-posterior and vertical axis, as well as the values of stride regularity in all three axes, are all significantly lower than those in the healthy control group (P<0.05). The findings of the analysis suggest that the application of three-dimensional accelerometer sensors proves efficacious and convenient for scrutinizing the symmetry and regularity of walking in individuals with idiopathic scoliosis. Distinctive irregularities in gait symmetry and regularity manifest in patients with idiopathic scoliosis, particularly within the antero-posterior and vertical direction. Moreover, the dynamic balance control strategy of the head in three-dimensional space among patients with idiopathic scoliosis exhibits a relatively conservative nature when compared to healthy individuals.

Effect of Progressive Balance Control Strategies on Chronic Ankle Instability in Middle-Aged Obese Women.

Chronic ankle instability (CAI) is a disease characterized by persistent feelings of instability in the ankle joint and a propensity for recurrent ankle sprains. It is often caused by ligamentous laxity or neuromuscular deficits. Middle-aged obese females represent a demographic subset at increased risk for CAI due to factors such as reduced proprioception and increased loading on the ankle joint. The gaps in the current evidence suggest that more research is needed on middle-aged obese females, who are particularly vulnerable to CAI due to physiological changes associated with poor balance. This study aims to determine the effect of progressive balance control strategies on CAI in middle-aged obese women. In this experimental study, 72 patients with CAI in middle-aged women were selected randomly using a simple random sampling method. Females aged 35-45 with a body mass index (BMI) greater than 27 kg/m2 and a history of ankle sprains greater than one and having residual symptoms. The experimental group (Group B) received progressive balance control strategies, and the conventional group (Group A) received conventional balance exercises. Foot and ankle ability measure (FAAM) scale, push-and-release test (PART), single-leg stance test (SLST), evaluations, and star excursion balance test (SEBT) were used for pre- and posttreatment. The experimental group post-intervention for static balance, dynamic balance, and postural control tests showed extremely significant improvement with a p-value of <0.0001. Between groups A and B, the dynamic balance was considered very significant, with a p-value of 0.0001. In the single-leg stance test, Group B's result was significantly greater than that ofGroup A's (63.4 + 16.1 and 63.4 + 16.1). PART results indicate that Group B is more significant than Group A (0.76 and 0.51, respectively). The study concluded that progressive balance control strategy training is effective in middle-aged obese women with CAI.

A treadmill running research protocol to assess dynamic visual acuity and balance for athletes with and without recent concussion history

Athletes interpret dynamic visual scenes quickly and accurately during physical exertion. It is important to understand how increased exertion may impact vision and cognition following sport-related concussion (SRC).Purpose To examine the effect of a treadmill running research protocol on the assessment of dynamic visual acuity (DVA) and balance for athletes with and without recent history of SRC.Methods Varsity athletes following recent SRC (CONC=12) were compared to athletes without SRC (ATHLETE=19). The DVA task presented a Tumbling ‘E’ target in four possible orientations during random walk (RW) or horizontal (H) motion at a speed of 30°/s. Participants performed DVA trials standing on a force plate (1000Hz) at four time points: 1) pre-exercise (PRE-EX), 2) immediately (POST1), 3) 10-minutes (POST10), and 4) 20-minutes post- exercise (POST20). Performance was calculated as a change in DVA score from PRE-EX and median response time (RT, ms). Balance control was analyzed using the root mean square of centre of pressure displacement (dCOP).Results Both groups maintained DVA scores for both motion types and exhibited immediate exercise-induced benefits on RT. Both groups had similar change in balance control strategy following treadmill exercise.Conclusion Both groups elicited similar exercise-induced benefits on DVA following exercise. A repeated measures assessment following vigorous exercise may provide meaningful insights about visual and neurocognitive functions for athletes returning to sport following concussion.

Sensory integration and segmental control of posture during pregnancy

BackgroundApproximately 25% of pregnant people fall, yet the underlying mechanisms of this increased fall-risk remain unclear. Prior studies examining pregnancy and balance have utilized center of pressure analyses and reported mixed results. The purpose of this study was to examine sensory and segmental contributions to postural control throughout pregnancy using accelerometer-based measures of sway. MethodsThirty pregnant people (first trimester: n = 10, second trimester: n = 10, third trimester: n = 10) and 10 healthy, nonpregnant control people stood quietly for one minute in four conditions: eyes open on a firm surface, eyes closed on a firm surface, eyes open on a foam pad, and eyes closed on foam. Postural sway was quantified using the root mean square accelerations in the anterior-posterior and medial-lateral directions from an inertial sensor at the lumbar region. Sensory sway ratios, segmental coherence and co-phase, were calculated to assess sensory contributions and segmental control, respectively. FindingsPregnant people did not display greater sway compared to healthy, nonpregnant controls. There were no group differences in vestibular, visual, or somatosensory sway ratios, and no significant differences in balance control strategies between pregnant and nonpregnant participants across sensory conditions. InterpretationThe small effects observed here contrast prior studies and suggest larger, definitive studies are needed to assess the effect of pregnancy on postural control. This study serves as a preliminary exploration of pregnant sensory and segmental postural control and highlights the need for future to hone the role of balance in fall risk during pregnancy.

Generalizability of foot placement control strategies during unperturbed and perturbed gait.

Control of foot placement is an essential strategy for maintaining balance during walking. During unperturbed, steady-state walking, foot placement can be accurately described as a linear function of the body's centre of mass (CoM) state at midstance. However, it is uncertain if this mapping from CoM state to foot placement generalizes to larger perturbations that could potentially cause falls. Recovery from these perturbations may require reactive control strategies not observed during unperturbed walking. Here, we used unpredictable changes in treadmill belt speed to assess the generalizability of foot placement mappings identified during unperturbed walking. We found that foot placement mappings generalized poorly from unperturbed to perturbed walking and differed for forward perturbation versus backward perturbation. We also used the singular value decomposition of the mapping matrix to reveal that people were more sensitive to backward versus forward perturbations. Together, these results indicate that a single linear mapping cannot describe the foot placement control during both forward and backward losses of balance induced by treadmill belt speed perturbations. Better characterization of human balance control strategies could improve our understanding of why different neuromotor disorders result in heightened fall risk and inform the design of controllers for balance-assisting devices.

Hierarchical Energy Management of DC Microgrid with Photovoltaic Power Generation and Energy Storage for 5G Base Station

For 5G base stations equipped with multiple energy sources, such as energy storage systems (ESSs) and photovoltaic (PV) power generation, energy management is crucial, directly influencing the operational cost. Hence, aiming at increasing the utilization rate of PV power generation and improving the lifetime of the battery, thereby reducing the operating cost of the base station, a hierarchical energy management strategy based on the improved dung beetle optimization (IDBO) algorithm is proposed in this paper. The first control layer provides bus voltage control to each power module. In the second control layer, a dynamic balance control strategy calculates the power of the ESSs using the proportional–integral (PI) controller and distributes power based on the state of charge (SOC) and virtual resistance. The third control layer uses the IDBO algorithm to solve the DC microgrid’s optimization model in order to achieve the minimum daily operational cost goal. Simulation results demonstrate that the proposed IDBO algorithm reduces the daily cost in both scenarios by about 14.64% and 9.49% compared to the baseline method. Finally, the feasibility and effectiveness of the proposed hierarchical energy management strategy are verified through experimental results.

Discrete control for state of charge balance in DC microgrids considering the disturbance of photovoltaics

This study examines State of Charge (SoC) balancing control in DC microgrids subject to photovoltaic (PV) fluctuations, aiming to optimize power distribution in energy storage systems influenced by PV disturbances. The proposed approach enhances both the lifespan of storage systems and microgrid stability. To mitigate voltage variation due to PV perturbation, the paper introduces an adjustment in droop control offset. Additionally, it presents a novel discrete Sliding Mode Controller (SMC) characterized by reduced parameter sensitivity, thus enhancing control responsiveness. A SoC balancing control strategy employing sliding mode control is developed to equalize SoC levels across Battery Energy Storage Systems during both charge and discharge cycles. The stability of this strategy is substantiated through the construction of a Lyapunov function. Simulations conducted in a distributed DC microgrid environment using Simulink/SimPower Systems demonstrate the efficacy of the discrete SMC and the SoC balancing algorithm, achieving uniform SoC in energy storage nodes during operation, with improved robustness against PV perturbations.

Supply and demand balance control strategy for microgrids considering uncertainty and disturbance based on online H∞ policy iteration

Abstract With the rapid growth of renewable energy generation, its proportion in power generation is increasing. Accompanied by this, due to the uncertain characteristics of renewable energy generation, the issue of imbalanced power supply and demand in microgrids has posed, which brings great challenges to the reliability of microgrid. In recent years, how to use energy storage system to solve this problem has become a hot research topic in microgrid. In this paper, an online H∞ policy iteration algorithm is proposed to control the output power of photovoltaic arrays and micro-gas turbines. At the same time, considering the uncertainty of the load demand in the microgrid system and the input disturbance of the micro gas turbine governor, the power supply and demand relationship of the microgrid can be balanced by the proposed control strategy. Finally, the effectiveness and practicality of the control strategy were demonstrated through simulation analysis.

A Two-Stage SOC Balancing Control Strategy for Distributed Energy Storage Systems in DC Microgrids Based on Improved Droop Control

A Two-Stage SOC Balancing Control Strategy for Distributed Energy Storage Systems in DC Microgrids Based on Improved Droop Control

Capacitor Voltage Balancing Control of MMC Sub-Module Based on Neural Network Prediction

The issue of sub-module (SM) capacitor voltage unbalance is a hot topic in the current research into the modular multilevel converter (MMC). An excellent strategy comprises mitigating the SM capacitor voltage imbalance by adjusting the SM on time. The traditional capacitor voltage balancing control regulates the speed to maintain accuracy. A unique SM capacitor voltage balancing control strategy is presented in this paper and is based on conventional capacitor voltage balance management and neural network prediction. Firstly, the SM capacitor voltage and arm current are speculated by operating the time series forecasting technique in real time, considering the dynamic changes in the SM capacitor voltage and arm current. Secondly, the SM capacitor voltage distinction between the actual and theoretical value is determined, and a deviation’s mixed Gaussian distribution is established to estimate its compensation voltage. Thirdly, the SM triggering sequence is anticipated by using the neural network along with the pilot values of the SM capacitor voltage, arm current, and the offset compensation value, and the control is executed. Finally, a three-phase, six-leg, eight-module, nine-level MMC model is built to verify the feasibility of the suggested approach.

A Discrete-Time Current Control Method for the High-Speed Permanent Magnet Motor Drive Using the Modular Multilevel Converter

High-speed permanent magnet motors (HSPMMs) have received attention in direct drive systems from the industry. Modular multilevel converters (MMCs) have become the most practical solution for HSPMMs in industrial applications due to the advantages of their highly modular structure, high-quality output and high reliability. In this article, the symmetrical discrete-time model of the MMC for the HSPMM drive is presented. Based on this symmetrical discrete-time model, the discrete-time current regulator has been designed. Moreover, the submodel (SM) capacitor energy balance models for MMC have been described, and the energy balance control scheme is introduced. Finally, the simulation and experimental results show that the presented discrete-time current regulator has a strong dynamic response at high speed (15 kr/min), and the SM capacitor voltage balance control is also achieved. Compared with the conventional PI current controller, the proposed discrete-time current regulator improves the current loop dynamic performance at high-speed, and the energy balance control scheme can ensure the SM capacitor voltage balance of the MMC.

Extension of Operating Range in Hybrid Cascaded H-Bridge Inverters with Capacitor Voltage Balancing Capability

In this article, a generalized control scheme is proposed to extend the operating range of three-phase hybrid cascaded H-bridge (HCHB) inverters into various voltage levels without necessitating alterations to the core structure or the integration of additional H-bridge submodules. This study addresses a critical challenge related to capacitor voltage drift at various modulation indices and power factors, which is a serious impediment to various applications. To overcome this challenge, a novel balancing control scheme has been developed based on the injection of two independent offset voltages to simultaneously control the DC-link and flying capacitors. A distinctive aspect of the proposed technique involves adjusting the common reference voltage to attain the nearest level in the same cluster, thereby mitigating the insufficiency of redundant switching states. The effectiveness of the proposed technique to regulate the capacitor voltages at various operating conditions has been verified through simulation and experimental results.

A Simple Optimal Trajectory and Thermal Balance Control Strategy for Full-Bridge Resonant Converter With Wide Voltage Range Application

A Simple Optimal Trajectory and Thermal Balance Control Strategy for Full-Bridge Resonant Converter With Wide Voltage Range Application<i />

A Novel Reinforcement Learning Balance Control Strategy for Electric Vehicle Energy Storage Battery Pack

Abstract Energy imbalance in electric vehicle energy storage battery packs poses a challenge due to design and usage variations. Traditional balancing control algorithms struggle to cope with large-scale battery data and complex nonlinear relationship modeling, which jeopardizes the stability of energy storage systems. To overcome this issue, we propose a reinforcement learning (RL)-based strategy for battery pack balancing control. Our approach begins with adaptive battery pack modeling followed by the employment of an active balancing control strategy to determine the duration of the balancing charge state and rank the balancing strength of individual battery pack cells. Subsequently, a RL network is employed to learn dynamic parameters that capture battery pack variations, enabling subsequent automatic learning and prediction of effective balancing strategies while simultaneously selecting the optimal control policy. Our simulation experiments demonstrate that our approach ensures an orderly charge and discharge process of battery pack cells, achieving an impressive balance efficiency of 91% when compared to other similar balancing control methods. Furthermore, the optimization of RL methods results in significant improvements in battery pack energy efficiency, stability, and operational costs. Notably, our method also outperforms other similar control methods in terms of energy utilization rates, establishing its superiority in this category.