Drift Control Research Articles

State-of-the-Art Reliability Analysis of Structural Drift Control Corresponding to the Critical Excitations

ABSTRACT As a matter of fact, structural drift is a random variable that is associated with several bases of the uncertainties related to the loading excitation and structural resistance. Hence, it seems essential to utilize the probabilistic philosophy to provide a design criterion of control the structural drift. The current study was conducted to propose a probabilistic approach to control the structural drift subjected to seismic loading. The main contribution of this manuscript is to propose a new sophisticated design criterion to control the structural drift using the reliability analysis. As-a-state-of-the-art, a new limit state function is established to be utilized for reliability analysis of the considered extreme event. To do so, several different steel frames are analyzed and investigated using the existing design criterion of the ASCE07 code. Also, the analysis of the critical excitations is conducted to deliberate the required target reliability indices for the considered limit state function. Accordingly, the reliability index spectrum is illustrated which revealed that the drift of the structures is related to the fundamental structural period. Eventually, based on the consistency of the reliability index consideration a stylish formula is proposed to control the drift reliability index corresponding to the target reliability indices constraints in the range of 2 to 4 (2 ≤ β ≤ 4). In addition to the main advantage of the proposed design criterion which is to provide a consistent range of the reliability level for different structures. Indeed, the analysis of the critical excitation shows that the reliability index spectrum varies by the fundamental frequency of the structure. Hence, in this research, a new structural drift criterion was proposed to sophisticatedly present the design criterion based on the fundamental structural period. Also, the proposed design criterion contains the deflection amplification factor to conclude the comprehensive inter-story drift control.

Detecting and tracking drift in quantum information processors

If quantum information processors are to fulfill their potential, the diverse errors that affect them must be understood and suppressed. But errors typically fluctuate over time, and the most widely used tools for characterizing them assume static error modes and rates. This mismatch can cause unheralded failures, misidentified error modes, and wasted experimental effort. Here, we demonstrate a spectral analysis technique for resolving time dependence in quantum processors. Our method is fast, simple, and statistically sound. It can be applied to time-series data from any quantum processor experiment. We use data from simulations and trapped-ion qubit experiments to show how our method can resolve time dependence when applied to popular characterization protocols, including randomized benchmarking, gate set tomography, and Ramsey spectroscopy. In the experiments, we detect instability and localize its source, implement drift control techniques to compensate for this instability, and then demonstrate that the instability has been suppressed.

Spray Backstop: A Method to Reduce Orchard Spray Drift Potential without Limiting the Spray and Air Delivery

Unmanaged spray drift from orchard pesticide application contributes to environmental contamination and causes significant danger to farmworkers, nearby residential areas, and neighbors’ crops. Most drift control approaches do not guarantee adequate and uniform canopy spray coverage. Our goal was to develop a spray backstop system that could block drifting from the top without any negative impact on spray coverage and on-target deposition. The design included a foldable mast and a shade structure that covered the trees from the top. We used a continuous loop sampling to assess and quantify the effectiveness of spray backstop on drift potential reduction. We also collected leaf samples from different sections of trees to compare on-target deposition and coverage. The results showed that the spray backstop system could significantly (p-Value < 0.01) reduce drift potential from the top (78% on average). While we did not find any statistical difference in overall canopy deposition with and without the backstop system, we observed some improvement in treetops deposition. This experiment’s output suggests that growers may be able to adjust their air-assist sprayers for a more uniform spray coverage without concern about the off-target movement of spray droplets when they employ the spray backstop system.

Active task-dependent control of ocular drift during natural fixation

Active task-dependent control of ocular drift during natural fixation

Three dimensional drift control at nano-scale in single molecule localization microscopy.

Super-resolution imaging based on single molecule localization of cellular structures on nanometer scale requires to record a series of wide-field or TIRF images resulting in a considerable recording time (typically of minutes). Therefore, sample drift becomes a critical problem and will lower the imaging precision. Herein we utilized morphological features of the specimen (mammalian cells) itself as reference markers replacing the traditionally used markers (e.g., artificial fiduciary markers, fluorescent beads, or metal nanoparticles) for sample drift compensation. We achieved sub-nanometer localization precision <1.0 nm in lateral direction and <6.0 nm in axial direction, which is well comparable with the precision achieved with the established methods using artificial position markers added to the specimen. Our method does not require complex hardware setup, extra labelling or markers, and has the additional advantage of the absence of photobleaching, which caused precision decrease during the course of super-resolution measurement. The achieved improvement of quality and resolution in reconstructed super-resolution images by application of our drift-correction method is demonstrated by single molecule localization-based super-resolution imaging of F-actin in fixed A549 cells.

WSN-Assisted UAV Trajectory Adjustment for Pesticide Drift Control

Unmanned Aerial Vehicles (UAVs) have been widely applied for pesticide spraying as they have high efficiency and operational flexibility. However, the pesticide droplet drift caused by wind may decrease the pesticide spraying efficiency and pollute the environment. A precision spraying system based on an airborne meteorological monitoring platform on manned agricultural aircrafts is not adaptable for. So far, there is no better solution for controlling droplet drift outside the target area caused by wind, especially by wind gusts. In this regard, a UAV trajectory adjustment system based on Wireless Sensor Network (WSN) for pesticide drift control was proposed in this research. By collecting data from ground WSN, the UAV utilizes the wind speed and wind direction as inputs to autonomously adjust its trajectory for keeping droplet deposition in the target spraying area. Two optimized algorithms, namely deep reinforcement learning and particle swarm optimization, were applied to generate the newly modified flight route. At the same time, a simplified pesticide droplet drift model that includes wind speed and wind direction as parameters was developed and adopted to simulate and compute the drift distance of pesticide droplets. Moreover, an LSTM-based wind speed prediction model and a RNN-based wind direction prediction model were established, so as to address the problem of missing the latest wind data caused by communication latency or a lack of connection with the ground nodes. Finally, experiments were carried out to test the communication latency between UAV and ground WSN, and to evaluate the proposed scheme with embedded Raspberry Pi boards in UAV for feasibility verification. Results show that the WSN-assisted UAV trajectory adjustment system is capable of providing a better performance of on-target droplet deposition for real time pesticide spraying with UAV.

Experimental study on damage detectable brace-type shear fuses

This paper proposes new brace-type shear fuses (BSFs) in series connection. The BSF consists of 2 perforated flat plates, 2 middle bridging plates and 2 side bridging plates and it is designed to dissipate seismic input energy efficiently via shear and bending of its steel strips. The BSF combines the advantages of buckling-restrained braces and shear slit dampers as it merely needs a single brace for installation in a braced frame, and it is damage visible and detectable. Stiffness and strength of BSFs are uncoupled so that it can be designed with sufficient flexibility, and better ductility can be realized. Five specimens were designed with different lengths and widths for the steel strips. The proposed BSFs presented good energy dissipation capacity and ductility, and it was found that the length and width of steel strip have great effect on strength, stiffness, energy dissipation capacity and deformation capacity. Formulae to predict the initial stiffness, yield load and ultimate load of the BSF are proposed. A formula predicting the damage level of a building installed with BSFs is also proposed through residual plastic rotation angle of steel strips. A six-story BSF braced frame was studied numerically to examine the effect of BSFs on maximum and residual drift control. Finally, a step-by-step design procedure was proposed for BSF braced frames.

Seismic performance of dual systems coupling moment‐resisting and buckling‐restrained braced frames

SummaryBuckling‐restrained braces (BRBs) have proven to be very effective in improving the seismic performance of existing and new structures. They provide strength, stiffness and add energy dissipation to the structure. However, being BRBs characterized by a low post‐elastic stiffness, their use may lead to residual deformations hindering the building's reparability and to excessive cumulative ductility demand possibly compromising the residual capacity of BRBs. To overcome these drawbacks, BRB frames (BRBFs) can be coupled with moment‐resisting frames (MRFs) to form dual systems. If properly designed, MRFs acting as back‐up frames allow the control of the residual drifts and the optimization of the performance of the BRBs. The contribution of this study is to provide insights into the performance and residual capacity of BRBFs‐MRFs dual systems and to shed light on the influence of the main BRB's design parameters. To this end, a nondimensional formulation of the equation of motion is introduced for a single degree of freedom system, and an extensive parametric study is performed for a set of natural ground motion records with different characteristics and scaled to various intensity levels. This allows the investigation of a wide range of configurations, considering different levels of the relative strength and ductility demand of BRBFs and MRFs, and obtains useful information for their design. Finally, two case study frames, modeled as two‐dimensional nonlinear multi‐degree of freedom systems, are analyzed, and the results were compared to those obtained from the nondimensional formulation to show the capabilities and the limitations of the adopted methodology and of the SDOF approximation.

Self-learning drift control of automated vehicles beyond handling limit after rear-end collision

Abstract Vehicles involved in traffic accidents generally experience divergent vehicle motion, which causes severe damage. This paper presents a self-learning drift-control method for the purpose of stabilizing a vehicle's yaw motions after a high-speed rear-end collision. The struck vehicle generally experiences substantial drifting and/or spinning after the collision, which is beyond the handling limit and difficult to control. Drift control of the struck vehicle along the original lane was investigated. The rear-end collision was treated as a set of impact forces, and the three-dimensional non-linear dynamic responses of the vehicle were considered in the drift control. A multi-layer perception neural network was trained as a deterministic control policy using the actor-critic reinforcement learning framework. The control policy was iteratively updated, initiating from a random parameterized policy. The results show that the self-learning controller gained the ability to eliminate unstable vehicle motion after data-driven training of about 60,000 iterations. The controlled struck vehicle was also able to drift back to its original lane in a variety of rear-end collision scenarios, which could significantly reduce the risk of a second collision in traffic.

Data-based reinforcement learning approximate optimal control for an uncertain nonlinear system with control effectiveness faults

An infinite horizon approximate optimal control problem is developed for a system with unknown drift parameters and control effectiveness faults. A data-based filtered parameter estimator with a novel dynamic gain structure is developed to simultaneously estimate the unknown drift dynamics and control effectiveness fault. A local state-following approximate dynamic programming method is used to approximate the unknown optimal value function for an uncertain system. Using a relaxed persistence of excitation condition, a Lyapunov-based stability analysis shows exponential convergence to a residual error for the parameter estimation and uniformly ultimately bounded convergence for the closed-loop system. Simulation results are presented which demonstrate the effectiveness of the developed method.

High-Speed Autonomous Drifting With Deep Reinforcement Learning

Drifting is a complicated task for autonomous vehicle control. Most traditional methods in this area are based on motion equations derived by the understanding of vehicle dynamics, which is difficult to be modeled precisely. We propose a robust drift controller without explicit motion equations, which is based on the latest model-free deep reinforcement learning algorithm soft actor-critic. The drift control problem is formulated as a trajectory following task, where the errorbased state and reward are designed. After being trained on tracks with different levels of difficulty, our controller is capable of making the vehicle drift through various sharp corners quickly and stably in the unseen map. The proposed controller is further shown to have excellent generalization ability, which can directly handle unseen vehicle types with different physical properties, such as mass, tire friction, etc.

AC and DC Differential Bridge Structure Suitable for Electrochemical Interfacial Capacitance Biosensing Applications.

This paper presents a capacitive differential bridge structure with both AC and DC excitation and balancing capability for low cost electrode-solution interfacial capacitance biosensing applications. The proposed series RC balancing structure offers higher sensitivity, lower susceptibility to common-mode interferences, and drift control. To evaluate the bridge performance in practice, possible effects of initial bridge imbalance due to component mismatches are investigated considering the required resolution of the balancing networks, sensitivity, and linearity. This evaluation is also a guideline to designing the balancing networks, balancing algorithm and the proceeding readout interface circuitry. The proposed series RC bridge structure is implemented along with a custom single frequency real-time amplification/filtering readout board with real-time data acquisition and sine fitting. The main specifications for the implemented structure are 8-bit detection resolution if the total expected fractional capacitance change at the interface is roughly 1%. The characterization and measurement results show the effectiveness of the proposed structure in achieving the design target. The implemented structure successfully achieves distinct detection levels for tiny total capacitance change at the electrode-solution interface, utilizing Microcystin-(Leucine-Arginine) toxin dilutions as a proof of concept.

Assessment for INS/GNSS/Odometer/Barometer Integration in Loosely-Coupled and Tightly-Coupled Scheme in a GNSS-Degraded Environment

With the increasing demands for seamless landvehicle navigation, systems with robust performance are required in highly urbanized areas. The traditional INS/GNSS integration is widely applied to solve this issue. However, the system still suffers from bad GNSS signal reception and INS time accumulated errors that seamlessness and stability are difficult to maintain. In this study, the performance of the low cost INS/GNSS with aiding sensors, such as an odometer and barometer, was evaluated for both the loosely-coupled (LC) scheme and tightly-coupled (TC) scheme. Moreover, considering barometric error accumulation, a vehicle-behavior based drift control method has been proposed. An experiment was conducted under harsh GNSS-degraded scenarios to assess the characteristics and performance for different sensor combinations, using single constellation (GPS) with single-frequency (L1 band) measurement. Overall, the TC scheme without additional strategies in detecting abnormal measurement encounters more challenges to achieve stable performance. In an INS/GNSS/barometer system with the proposed drift control method, error accumulation under unpredictable environmental changes was successfully mitigated in both schemes. The proposed method can maintain a height accuracy of 2-meter level root mean square even after a long term operation. In an INS/GNSS/odometer combination, improvements were observed in the horizontal and vertical direction for both schemes. According to statistical analysis, an INS/GNSS/odometer/barometercombination shows 16.57% and 6.11% in the horizontal, and 30.71% and 71.28% in the vertical for the LC scheme and TC scheme, compared with an INS/GNSS combination.

Tuning Memristivity by Varying the Oxygen Content in a Mixed Ionic–Electronic Conductor

AbstractThe rising interest shown for adaptable electronics and brain‐inspired neuromorphic hardware increases the need for new device architectures and functional materials to build such devices. The rational design of these memory components also benefits the comprehension and thus the control over the microscopic mechanisms at the origin of memristivity. In oxide‐based valence‐change memories, the control of the oxygen drift and diffusion kinetics is a key aspect in obtaining the gradual analog‐type change in resistance required for artificial synapse applications. However, only a few devices are designed with this in mind, as they are commonly built around ionic insulating active materials. This shortcoming is addressed by using a mixed ionic–electronic conductor as functional memristive material. This work demonstrates how the oxygen content in La2NiO4+δ (L2NO4), tuned through post‐annealing treatments, has a critical influence on the memory characteristics of L2NO4‐based memristive devices. The presence of interstitial oxygen point defects in L2NO4 affects both its structure and electrical properties. High oxygen stoichiometry in the pristine state leads to an increased electrical conductivity, ultimately resulting in an improved memory window with highly multilevel, analog‐type memory programing capabilities, desirable for analog computing and synaptic applications in particular.

A new control approach for automated drifting in consideration of the driving characteristics of an expert human driver

This paper presents a new control approach for automated drifting in consideration of how expert drivers conduct drifting. The expert drivers stabilize their vehicles at high sideslip angle using not prior knowledge of tire dynamics and equilibrium but current vehicle states. By mimicking how these expert drivers control their vehicles at high sideslip angle, the proposed controller is able to control the vehicle at high sideslip angle using only current vehicle states, i.e without prior knowledge of tire and drift equilibria. Specifically, the proposed controller can perform steady state drifting without the knowledge of the equilibrium of the vehicle system. The proposed controller consists of three consecutive parts. First, the supervisor determines the desired yaw rate and rear longitudinal slip ratio. Second, the upper-level controller calculates the desired front lateral force and rear longitudinal force to track the desired motions. Third, the lower-level controller converts the upper-level controller’s desired forces into steering wheel angle and gas pedal input, which are actual control inputs of vehicles. The proposed algorithm has been investigated via vehicle tests. A rear wheel driven mid-sized vehicle with limited slip differential and internal combustion engine was utilized for testbed. The test results indicate that the proposed algorithm can successfully conduct automated drift maneuvers. Furthermore, the stability of the closed-loop drift control system has been proved by using Lyapunov stability analysis and estimating Region of Attraction (RoA). The vehicle test results are superimposed on the estimate of RoA, and it has been shown that vehicle states within the estimate of RoA converge well to the desired motions. In addition, the comparison of the proposed algorithm with the previously developed drifting control algorithm was conducted. In contrast to the drifting control algorithm that was based on drift equilibrium, the proposed control algorithm is capable of conducting drift maneuvers on both high friction roads and low friction roads without prior knowledge of the tire model and road friction coefficient.

Seismic design and pseudo-dynamic tests of blind-bolted CFT frames with buckling-restrained braces

A novel dual system composed of blind bolted end plate concrete filled steel tube (BECFT) composite frames and buckling-restrained braces (BRBs) was proposed and presented in this paper. The direct displacement-based design (DDBD) method was modified and used to design the BECFT composite frames with BRBs (BRB-BECFT) at a certain seismic hazard level. Meanwhile, a series of pseudo-dynamic tests (PDTs) were conducted on two specimens of 2/3-scaled two-story, one-bay BRB-BECFT composite frames. The test observations at different seismic hazard levels were recorded. It was indicated that the BRB-BECFT frame system exhibited reasonable failure mode, good hysteretic behavior, high ductility and sufficient energy-dissipating capacity. The installation of BRBs effectively enhanced the lateral stiffness and resistance of the dual system in comparison with their bare counterparts. Moreover, the inter-story drift responses of both specimens at the frequent occurrence earthquake (FOE) and the maximum considered earthquake (MCE) levels were less than the pre-defined values, and the experimental base shears were also close to the analytical results at the MCE level, suggesting the modified DDBD method could provide good control of drifts for the dual system at a target loading level. These research results presented a good alternative for application in earthquake resistant design of braced frame structures.

СТРУКТУРНО – ФУНКЦІОНАЛЬНА МОДЕЛЬ РОБОТИ ЕЛЕКТРОННОЇ СИСТЕМИ КУРСОВОЇ СТІЙКОСТІ (ESP)

Розроблено імітаційну модель управління поведінкою транспортного засобу при заносах з використанням системи курсової стійкості (ESP). Створено динамічну імітацію роботи контуру гальмівної системи, яка дозволяє ознайомитись з роботою контуру в динаміці, що значно покращує розуміння процесу гальмування; розроблено інтерактивну схеми роботи ESP та АВS. Зона виводу інформації під час роботи моделі дозволяє візуалізувати проходження автомобілем тестової траси та отримувати індикацію швидкості автомобіля та повороту керма та індикацію втручання ESP. Таким чином, отримана комп’ютерна модель управління автомобілем при заносах з врахуванням роботи ESP. яка дозволяє спостерігати в динаміці роботу ESP та прослідковувати зв’язки, які виникають при роботі системи ESP та ABS. Застосування такого підходу дозволяє проводити імітаційне моделювання за різними сценаріями, залежно від формування різноманітних ситуацій, практично необмеженої складності.Ключові слова: імітаційна модель, заноси, керування транспортним засобом, ESP, АВS, контур гальмівної системи, швидкість, поворот керма.&#x0D;

Control of spiral drift by using feedback signals from a circular measuring domain in oscillatory media

In this paper, a non-local feedback is used to force spiral waves in the oscillatory system modeled by the complex Ginzburg-Landau equation, where the feedback signal is derived from a circular measuring domain. It is found that the spiral tip could be driven to follow an attractor after a period of drift. The existence of multiple types of attractors, which include a point attractor at the measuring center and a set of circular attractors concentric with the measuring domain, is illustrated. Which to be chosen depends on the direction of the spiral initial drift and the distance between the initial tip position and the measuring center. Here the diameter of the circular attractor has a periodic change with the size of the measuring domain, but is not affected by the movement of the measuring domain. Correlation between the tip drift and the feedback signal is analyzed, and the modulus function of the feedback signal will has a constant value after the spiral tip arrives at the attractors. If the feedback signal is generated from the measuring domain far away from the position of the initial spiral tip, the spiral breakup can be caused by the feedback control, and it fist occurs near the boundary and then invades inward until the area of the remaining spiral is small enough. The effect of the feedback gain, the delay time and the scaling parameter is also considered.

Wave Control Performance of Tide-Adapting Low-Crested Structure

Hur, D.S.; Jung, K.H.; Park, J.R., and Lee, W.D., 2019. Wave control performance of tide-adapting low-crested structure. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 116-120. Coconut Creek (Florida), ISSN 0749-0208.Low-Crested Structures (LCSs) are aesthetically apt coastal structures with wave and sand drift control functions. However, they are inappropriate in waters where the tidal range is large because the crest width and height must be above certain levels to allow the breakwater to carry out these functions. Forced wave breaking cannot be induced during high tide because the crest depth increases. Therefore, a Tide-Adapting Low-Crested Structure (TA-LCS) is proposed to overcome the problems caused by large tidal ranges. The hydraulic performance of the proposed LCS was evaluated and compared with that of a typical LCS via hydraulic model experiments. The typical LCS showed an excellent wave screening effect with an average transmission coefficient of 0.4 under the conditions of Fb/Hi=0.29–0.67 and B/Li=0.09–0.15. The wave screening performance of the new type of LCS was 9.5–28.8 % lower than that of the typical LCS. However, the wave screening performance of the new type of LCS decreased only by 9.1–10.4 % under the condition of Fb/Hi≤1 and only by 24.3 % under the condition of Fb/Hi=4. Therefore, the new type of LCS proposed in this study is expected to exhibit its wave control functions during high tide even when installed in a coastal area with a large tidal range.

Adaptive Negative Stiffness Device based nonconventional Tuned Mass Damper for seismic vibration control of tall buildings

Adaptive Negative Stiffness Device (ANSD) has been developed recently for passive vibration control of structures. ANSD emulates negative stiffness behavior (by exerting force toward the direction of motion) to a structure, so that, the combined structure-ANSD system shows smooth elasto-plastic force-deformation behavior with virtual yielding at target (“engaging”) displacement. The device has been studied analytically and its behavior has been demonstrated experimentally in simply supported bridge model and in Single Degree of Freedom (SDOF) structure considering limited input excitations. However, efficient and cost-effective exploitation of true potential of ANSD deserves further studies. With this being the eventual goal, in this study, we explore the performances of ANSD in seismic vibration control of a tall building by implementing a nonconventional Tuned Mass Damper (TMD) with drift control. In absence of a methodology for choice of ANSD parameters in literature, reported till date, we employ a tuning criteria for nonconventional TMD, on which the drift control is imposed as a constraint, given the special significance of drifts in tall buildings. The criteria of tuning and drift control are shown to be mutually conflicting and an algorithm is presented to address the same. Simplifying assumptions are made to develop the tuning criteria in presence of nonlinearity in ANSD and P−δ nonlinearity in tall building. A Reduced Order Modeling (ROM) approach for the building-ANSD system is developed to facilitate the algorithmic computations. Robustness of our design approach is shown under an acceptable level of detuning of TMD and near fault pulse type motions. Comparative assessment with a conventional design approach is presented to show the improvements. A step by step illustration of the developed methodology is briefly touched on in context of modern performance based approach. The study is a first step toward the possible utility of ANSD in controlling seismic vulnerability of tall buildings.