Internal Disturbances Research Articles

Analysis of the rule of window-to-wall ratio on energy demand of residential buildings in different locations in China

Building energy demands are influenced by the window-to-wall ratio (WWR). The impact of the WWR on the energy demand in the same area has been researched by software. However, the impact of the WWR on the energy demand of buildings in different locations of China has not been investigated using the energy balance equation. The equation for the indoor temperature variation under various internal and external disturbances was provided in this study. The relationship between parameters A and B and the change in indoor temperature was proven. China's Harbin, Beijing, and Chengdu air-conditioning and heating loads, as well as the impact of changing WWR on the rate of energy savings for air-conditioning and heating energy demand, were studied. After investigating the changes in the cooling and heating loads in various cities under various WWRs, the suitable relationship between the cooling and heating loads and the WWR of three urban units was discovered. The findings indicated that despite the three cities' various climates and the diverse energy demands for air conditioning and heating in each city, with the same change in the WWR of urban buildings, the change rate of the air conditioning and heating loads in each city was near. Meanwhile, the heating and cooling loads were linear with WWR.

Adaptive Neural Network Extended State Observer-Based Finite-Time Convergent Sliding Mode Control for a Quad Tiltrotor UAV

The internal and external disturbance of the quad tiltrotor UAV stem from its rotor tilting motion and wind disturbance, which affect the control stability of the quad tiltrotor UAV in full flight. This paper proposes a control law design method based on the Adaptive Neural Network Extended State Observer-based Finite-Time Convergent Sliding Mode Control (ANNESO-FTCSMC). The adaptive neural network obtains the unknown total disturbance term that needs to be compensated in the finite-time convergent sliding mode control. An extended state observer is used to estimate the state variables of the controlled plant. The stability of the ANNESO-FTCSMC controller is proved with the Lyapunov stability theory. The unknown total disturbance as the expanded state variable of the state observer has the advantage of high adaptability, and the ANNESO-FTCSMC has a strong ability to compensate for the internal and external disturbances of the system. Compared with traditional sliding mode control, ANNESO-FTCSMC does not contain switching terms, so ANNESO-FTCSMC is chattering-free and converges faster. Based on this method, the flight control system of the quad tiltrotor UAV is designed and verified by hardware-in-loop simulation. The hardware-in-loop simulation results of attitude control in different flight modes and trajectory tracking control in full flight show that the ANNESO-FTCSMC controller is suitable for the flight control of quad tiltrotor UAV. Compared with the PID controller and ADRC controller, ANNESO-FTCSMC controller has more stable flight state of quad tiltrotor UAV under different flight modes and the same total disturbance. The transition process of ANNESO-FTCSMC controller from helicopter mode to airplane mode is also smoother and will not have large fluctuations. Therefore, ANNESO-FTCSMC controller has strong anti-disturbance and robustness.

H∞ Control for Oscillator Systems With Event-Triggering Signal Transmission of Internet of Things

This article proposes to design a distributed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$H_{\infty} $ </tex-math></inline-formula> optimal control algorithm for Van der Pol oscillators with unknown internal dynamics, input constraints and external disturbances, via event-triggering signal transmission of the Internet of Things (IoT). First, the graph theory for the IoT is introduced. Second, the dynamics of Van der Pol oscillators are transformed into the tracking dynamics which cooperate via the IoT network. Third, unlike the existing online optimal control algorithms using adaptive dynamic programming, we design an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$H_{\infty} $ </tex-math></inline-formula> optimal control algorithm employing an event-triggering signal transmission mechanism to reduce the burden of communication resource and computation bandwidth of the IoT network. As the triggering condition and approximation parameter update policies are appropriately designed, the algorithm guarantees that the Zeno phenomenon is free, the consensus errors are uniformly ultimately bounded, and the external disturbance is compensated. Finally, numerical simulation results with comparison to the time-triggering algorithms confirm the effectiveness of the proposed algorithm.

Research on Automatic Driving Control of Tracked Transport Vehicle Based on Labview

HighlightsAn indirect Kalman filter algorithm is proposed to fuse GNSS/INS positioning information.Detailed kinematics and dynamics model of track vehicles was established.An MPC-based double-layer closed-loop controller combined with tracked vehicle model is designed.Tracked transport vehicle performs well in path tracking on soft soil road.Abstract. Orchards in hills and mountainous regions are more occluded and single satellite navigation is unstable. Therefore, the indirect Kalman filter information fusion algorithm was proposed to achieve high-precision positioning by establishing a state error equation based on GNSS/INS. A complete kinematics and dynamics model of tracked chassis was established. A double-layer closed-loop controller based on model predictive control (MPC) was designed. An MPC controller based on the kinematics model in the outer loop was designed to output the expected control value of the tracked transporter. The inner loop design was based on the extended state observer of the dynamic model to estimate and compensate for the internal and external disturbances of the system. The performance test was based on a tracked chassis platform. The test results presented that when driving at a speed of 0.50 m/s under soft soil road conditions, the maximum lateral deviation was 0.15 m, and the average absolute deviation was 0.05 m. This high level of control accuracy means that this control design enables the transfer vehicle to follow the navigation path precisely and complete its task. Keywords: Hills and mountainous regions, Integrated navigation, Model predictive control, Vehicle dynamics model.

Methodology for the synthesis of the system of phase synchronization of coherent demodulators with a variable structure of open communication

One of the factors of internal disturbances and obstacles in the operation of the synchronization system, which directly affect the accuracy of the estimation of the carrier frequency and the dynamics of the entire system, are transient processes caused by the system’s reaction to the transition from one stationary state to another stationary state. At the current stage of research devoted to the issue of minimizing the influence of the transient process on the operation of the phase synchronization system, increasing the speed and reducing the transient component of the phase error, which is generated by the transient processes, was solved by synthesizing the open connection of the synchronization system under the condition of minimizing the phase error in steady and transient modes of operation. In the work, a mathematical model and a technique based on it were developed, which allow the synthesis of open communication with a variable structure in the combined synchronization system of satellite telecommunications, which ensure the minimization of the influence of transient processes on the efficiency of the synchronization system. The open communication scheme with a variable structure proposed in the work allows to minimize the impact of the transient process on the efficiency of the synchronization system by reducing the time of the transient process by taking into account the level of harmful disturbances of the transient process. The evaluation of the possibility of an open connection with a variable structure in terms of the effect on the time of the transition process carried out in the work showed that by logically switching to the branch of the open connection with the corresponding values of the time operator, it is possible to achieve up to a 6.7 times reduction in the time of the transition process.

Comparative study of field-oriented control of an induction machine with inter-turn short-circuit in healthy and faulty cases

The vector control of an induction machine is among the most used controls, the inter-turn short-circuit fault is a very common fault in this type of machine. Vector controllers use current regulators that are highly insensitive to internal disturbances and can therefore mask the onset of a short-circuit fault. In this article we propose simulations allowing to study the behavior of the indirect field-oriented control when an inter-turn short-circuit fault appears. The primary aim of this article is a comparative study of the effect of this type of defect on estimated quantities such as rotor flux, slip and electromagnetic torque. The results of the simulation show that these estimated quantities can be used as fault indicators instead of the stator currents. The results of this comparative study also show that the ripple of the estimated rotor flux is a very good indicator of this type of fault in this type of regulator-machine association.

Investigating the Association of Quantitative Gait Stability Metrics With User Perception of Gait Interruption Due to Control Faults During Human-Prosthesis Interaction.

This study aims to compare the association of different gait stability metrics with the prosthesis users' perception of their own gait stability. Lack of perceived confidence on the device functionality can influence the gait pattern, level of daily activities, and overall quality of life for individuals with lower limb motor deficits. However, the perception of gait stability is subjective and difficult to acquire online. The quantitative gait stability metrics can be objectively measured and monitored using wearable sensors; however, objective measurements of gait stability associated with human's perception of their own gait stability has rarely been reported. By identifying quantitative measurements that associate with users' perceptions, we can gain a more accurate and comprehensive understanding of an individual's perceived functional outcomes of assistive devices such as prostheses. To achieve our research goal, experiments were conducted to artificially apply internal disturbances in the powered prosthesis while the prosthetic users performed level ground walking. We monitored and compared multiple gait stability metrics and a local measurement to the users' reported perception of their own gait stability. The results showed that the center of pressure progression in the sagittal plane and knee momentum (i.e., residual thigh and prosthesis shank angular momentum about prosthetic knee joint) can potentially estimate the users' perceptions of gait stability when experiencing disturbances. The findings of this study can help improve the development and evaluation of gait stability control algorithms in robotic prosthetic devices.

Deep-Reinforcement-Learning-Based Active Disturbance Rejection Control for Lateral Path Following of Parafoil System

The path-following control of the parafoil system is essential for executing missions, such as accurate homing and delivery. In this paper, the lateral path-following control of the parafoil system is studied. First, considering the relative motion between the parafoil canopy and the payload, an eight-degree-of-freedom (DOF) model of the parafoil system is constructed. Then, a guidance law containing the position deviation and heading angle deviation is proposed. Moreover, a linear active disturbance rejection controller (LADRC) is designed based on the guidance law to allow the parafoil system to track the desired path under internal unmodeled dynamics or external environmental disturbances. For the adaptive tuning of the controller parameters, a deep Q-network (DQN) is applied to the LADRC-based path-following control system, and the controller parameters can be adjusted in real time according to the system’s states. Finally, the effectiveness of the proposed method is applied to a parafoil system following circular and straight paths in an environment with wind disturbances. The simulation results show that the proposed method is an effective means to realize the lateral path-following control of the parafoil system, and it can also promote the development of intelligent controllers.

Dual-stage fast tool servo cascading a primary normal-stressed electromagnetic stage with a secondary piezo-actuated stage

The dual-stage actuation effectively extends the dynamic response and tracking accuracy of conventional fast tool servos (FTS). In this study, a normal-stressed electromagnetic stage is deliberately designed as the primary stage to cascade with a secondary piezo-actuated stage, constructing a new medium-range dual-stage FTS. Analytical models for both the normal-stressed actuator and the flexure mechanisms are established. The mechanical and electromagnetic parameters are selected and verified by finite element simulation, targeting the desired motion stroke and the maximized natural frequency. The prototype using the designed parameters is tested to have an actual stroke of 80μm and a first resonant frequency around 814 Hz. The dual-stage FTS employs a decoupled control strategy to track the desired trajectory precisely. As for the main controller, an additional disturbance observer is designed to work with the typical PID controller to compensate for both the internal nonlinear dynamics and external disturbances for each stage. The practical result demonstrates that the closed-loop bandwidth can be improved from 220 Hz to 500 Hz by cascading the secondary stage. As for the tracking of a complex trajectory with multiple frequencies, a motion error of around ±0.8μm was achieved, which is less than 30% of that obtained by the primary stage alone.

Synthesis of an Invariant Automatic Control Systems with an Internal Model

The article is devoted to the modernization of typical cascade automatic control systems with stabilizing and corrective PI controllers. Such automatic control systems, in addition to the main signal (of adjustable value), use an additional leading signal that reacts to the disturbance faster than the main one. The leading signal effectively compensates for internal disturbances arising in the system by adjusting the stabilizing controller. The temperature control system of superheated steam boiler units of thermal power plants may be taken as an example. The task of determining the configuration parameters of such dual-circuit systems is quite difficult. With a relatively low inertia of the internal circuit, the speed of the stabilizing controller is quite high, and transients in it do not affect the quality of regulation in the external circuit with a corrective controller. This makes it possible to calculate the optimal settings of the latter only by the dynamic characteristics of the inertial section using conventional methods developed for single-circuit systems. The main disadvantage of such automatic control systems is that they do not allow, with close inertia of the contours, to significantly improve the quality of working out the main impacts during the jump of the task, internal and external disturbances. To eliminate this drawback, an invariant cascade automatic control system with an internal model is proposed that takes into account the dynamics of both the internal and external contours with an inertial section of the object when choosing the structure and setting up the corrective controller. In this case, the internal model is used to fully compensate for the main feedback of the system when working out the task signal, as well as to isolate an equivalent external disturbance, for which an invariance differentiator is used to compensate. The invariant cascade automatic control system makes it possible to significantly increase the speed and accuracy compared to the standard one.

Control of Unstable Systems Using a 7 DoF Robotic Manipulator

Robotic manipulators are widely used in industrial applications, and their rigidity and flexibility are very important factors during their deployment. However, their usage is not limited to repetitive point-to-point tasks and can be used for more real-time control of various processes. This paper uses a 7-degrees-of-freedom manipulator to control an unstable system (Ball and Plate) as a proof of concept. The Ball and Plate system is widely used for testing algorithms designed for unstable systems, and many recent works have dealt with robotic manipulators as a control motion system. Robots are not usually used to control unstable systems, but bipedal robots are an exception. This paper aims to design a controller capable of stabilizing an unstable system with solid robustness while keeping actuator action values as low as possible because these robots will be indented to work for a prolonged time. An algorithm for an LQ polynomial controller is described and designed, and the whole setup is tested for ball stabilization in the center. The results show that the designed controller stabilizes the ball even with large external and internal disturbances while keeping the controller effort as low as possible.

3D hybrid formation control of an underwater robot swarm: Switching topologies, unmeasurable velocities, and system constraints

This paper addresses formation control of underactuated autonomous underwater vehicles in three-dimensional space, using a hybrid protocol that combines aspects of centralized and decentralized control with constraints that are particular to underwater vehicles, including switching topologies, unmeasurable velocities, and system constraints. Using a distributed leader–follower model, the hybrid formation protocol does not require velocity sensing, access to global information, or static and connected topologies. To handle switching jointly connected networks—that is, to tolerate temporary disconnections—a distributed observer is designed for followers to cooperatively estimate leader states using local measurements and local interactions. On this basis, a compound formation control strategy is proposed to achieve geometric convergence. Firstly, cascaded extended state observers are developed to recover the unmeasurable velocities and unknown dynamic uncertainties induced by internal model uncertainty and external disturbances. Secondly, an improved three-dimensional line-of-sight guidance law at the kinematic level is used to address the underactuated configuration and the nonzero attack and sideslip angles. Thirdly, to overcome potential instability as a result of system constraints, including velocity constraints and input saturations, two adaptive compensators in the dynamic controller are used to address the negative effects of truncation. Using the proposed approach, the estimation errors and formation tracking errors are proved to be uniformly and ultimately bounded. Additionally, the numerical simulation results verify the performance of the approach and demonstrate improvement over both distributed and centralized state-of-the-art approaches.

Energy-saving optimization on active disturbance rejection decoupling multivariable control

An industrial control process multiple-input multiple-output (MIMO) coupled system is analyzed in this study as an example of a Loss of Coolant Accident (LOCA) simulation system. Ordinary control algorithms can complete the steady state of the control system and even reduce the response time to some extent, but the entire system still consumes a large amount of energy after reaching the steady state. So a multivariable decoupled energy-saving control method is proposed, and a novel energy-saving function (economic function, Eco-Function) is specially designed based on the active disturbance rejection control algorithm. Simulations and LOCA simulation system tests show that the Eco-function algorithm can cope with the uncertainty of the multivariable system's internal parameters and external disturbances, and it can save up to 67% of energy consumption in maintaining the parameter steady state.

A Fuzzy Backstepping Attitude Control Based on an Extended State Observer for a Tilt-Rotor UAV

In order to overcome the influence of internal and external disturbances caused by rotor tilt motion and gust disturbance on the full flight mode control of a tilt-rotor unmanned aerial vehicle (UAV), a design method using fuzzy backstepping control based on an extended-state observer (FBS-ESO) is proposed. In this paper, fuzzy control is used to tune the parameters of the backstepping control law online, and the extended-state observer estimates the total disturbance of the controlled system to improve the controller’s robustness and anti-disturbance capability. This paper designs the attitude control system of a tilt-rotor UAV based on an FBS-ESO controller. The control performance of the FBS-ESO controller is tested in a hardware-in-loop simulation of the attitude control system. The simulation results show that changing the rotor tilt angle will destroy the stability of the traditional backstepping controller and active disturbance rejection controller (ADRC). In contrast, the FBS-ESO controller maintains good control performance. In addition, the performance of the FBS-ESO controller is not be significantly affected by adding external gust disturbance or changing the UAV parameters in the simulation. These disturbances significantly impact the traditional backstepping controller and ADRC. Therefore, the FBS-ESO controller has better anti-disturbance capabilities and robustness, as well as higher attitude control accuracy.

Spatio-Temporal Pattern and Influence Mechanism of Rural Human Settlements System Resilience: Case from China

The study of rural habitat systems from the perspective of resilience is of great significance in revealing the inner laws of the evolution of the rural human settlements system and promoting sustainable rural development. This study aims to explain the theoretical connotation of the rural human settlements system resilience (RHSSR), construct an evaluation system and zoning rules for rural habitat system resilience, and explore the spatial distribution pattern of rural habitat system resilience in China and the factors influencing the differences in the level of rural resilience using 30 Chinese provinces as examples to provide effective governance solutions for sustainable rural development. The results show that: (1) The RHSSR refers to the sustainability of the RHSS; i.e., the ability of a system to absorb and adapt to internal and external disturbances and shocks by adjusting the structure and scale of its internal elements, discarding the original inapplicable state to the greatest extent possible and creating a new recovery path to another new equilibrium state. (2) The overall downward trend of RHSSR in 30 Chinese provinces between 2000 and 2020 is consistent with the fact that a large number of villages have died out in China in recent years. (3) The RHSSR is higher in eastern China than in central and western China; although the regional gap is gradually narrowing. (4) An analysis of the evolutionary trend of the RHSSR shows that the northeastern and eastern regions of China belong to the major evolution area of the RHSSR; most areas in central and western China belong to the degraded vulnerable area of the RHSSR, while the potential recession area of the RHSSR is more scattered, mainly in Beijing, Tianjin, and Inner Mongolia in northern China, Chongqing, Hubei, and Qinghai in central China, and Guangdong and Fujian in the southern China region of Guangdong and Fujian. (5) The results of the analysis of geographical detectors show that the effect of the basic-driven factors in the RHSSR decreases significantly with time, while the effect of the core-driven and externally-driven factors increases, and the effect of the two factors is greater than that of the single factor. Among them, industrial structure (IS) has an important influence on the spatial differentiation of the resilience level of rural human settlements system. (6) Optimization strategies are proposed in terms of spatial planning; industrial integration and public participation for the development of different sub-regions.

Chain Network Control with Delay by an Auxiliary Loop Method

The article is devoted to the development of control algorithms for a network of agents of a chain network, each agent of which is a linear plant with state delay, subject to the action of external disturbances under conditions of a priori uncertainty. In each agent of the network, the output of the previous agent is monitored, and the signal from the leading subsystem arrives only at the first agent of the network, the communication is one-way. Taking into account the time delay in the models of each agent of the network of such a structure makes them close to real ones. In agent control systems, disturbances are compensated by implementing the principle of invariance, namely, in each network agent, compensation for the action of external disturbances acting on the network agent from the outside, as well as internal disturbances caused by various modes of operation of the plant, is carried out by generating a special disturbance signal, and then it subsequent compensation with the help of an auxiliary loop and Khalil observers. A numerical example of a chain network consisting of four linear control plants is given under the conditions of interval uncertainty of the parameters of their mathematical models, state delay and the action of external uncontrolled disturbances. Numerical simulation was carried out in Matlab Simulink. Graphs of transient processes for tracking errors of agents of the chain network are presented, confirming the theoretical conclusions and illustrating the good performance of the control algorithms for the chain network.

A Trajectory Tracking Approach for Aerial Manipulators Using Nonsingular Global Fast Terminal Sliding Mode and an RBF Neural Network

An unmanned aerial manipulator (UAM) is a novel flying robot consisting of an unmanned aerial vehicle (UAV) and a multi-degree-of-freedom (DoF) robotic arm. It can actively interact with the environment to conduct dangerous or inaccessible tasks for humans. Owing to the underactuated characteristics of UAVs and the coupling generated by the rigid connection with the manipulator, robustness and a high-precision controller are critical for UAMs. In this paper, we propose a nonsingular global fast terminal sliding mode (NGFTSM) controller for UAMs to track the expected trajectory under the influence of disturbances based on a reasonably simplified UAM system dynamics model. To achieve active anti-disturbance and high tracking accuracy in a UAM system, we incorporate an RBF neural network into the controller to estimate lumped disturbances, including internal coupling and external disturbances. The controller and neural network are derived according to Lyapunov theory to ensure the system’s stability. In addition, we propose a set of illustrative metrics to evaluate the performance of the designed controller and compare it with other controllers by simulations. The results show that the proposed controller can effectively enhance the robustness and accuracy of a UAM system with satisfactory convergence. The experimental results also verify the effectiveness of the proposed controller.

Design and full-link trajectory tracking control of underwater snake robot with vector thrusters under strong time-varying disturbances

In this paper, an underwater snake robot with vector thrusters and axis-intersect joints is designed. The dynamic model of the newly designed robot is established. A new decoupling control strategy is proposed for full-link trajectory tracking. The control strategy decouples the movements between the body and the links. The trajectory of the body (represented by the head link) is controlled by thrusters, and the rest links follow its trajectory by controlling the relative angles to the head link with servo motors on the joints. To eliminate the influence of strong time-varying external and internal disturbances, the control method based on sliding mode and a nonlinear disturbance observer with linear matrix inequality is proposed to realize the full-body trajectory tracking. The results show that the proposed method performs better than the reference under strong time-varying external and internal disturbances.

Stability Enhancement of Battery-Testing DC Microgrid: An ADRC-Based Virtual Inertia Control Approach

Power batteries play a vital role in electric vehicle (EV) industry. To evaluate their charging and discharging performance and achieve energy recovery, a power accumulator battery testing system (PABTS) based DC-microgrid (DC-MG) is proposed. However, during battery testing, frequent charging and discharging current test may endanger the stability of the PABTS DC-MG. Although, the traditional virtual inertia control (VIC) approach can stabilize the DC-bus voltage, its anti-interference ability is still limited. To solve this problem, an active disturbance rejection control (ADRC) based VIC control scheme is proposed, wherein the VIC approach provides virtual inertia for the system, and the ADRC is derived and modeled using the first-order virtual inertia equation. The external and uncertain internal disturbances in the system are considered for the total disturbance estimation. This disturbance is suppressed by feedback compensation, thereby greatly improving the system robustness. Finally, the effectiveness of the proposed ADRC-VIC method is further verified by experimental results on the laboratory hardware prototype under different scenarios.

Real-time implementation of Fuzzy Logic Controller based on chicken swarm optimization for the ball and plate system

Abstract The ball and Plate (BaP) system is the typical example of the nonlinear dynamic system that is used in a wide range of engineering applications. So, many researchers in the control field are using the Bap system to check robust controllers under several points that challenge it, such as internal and external disturbances. Our manuscript proposed a position control intelligent technique with two directions (2D) for the BaP system by optimized multi Fuzzy Logic Controllers (FLC’s) with Chicken Swarm Optimization (CSO) for each one. The gains and rules of the FLC’s can tune based on the CSO. This proposal utilizes the ability of the FLC’s to observe the position of the ball. At our work, the BaP system that belonged to Control Laboratory/Systems and Control Engineering department is used for real-time proposal implementation. The results have been showing a very good percentage enhancement in settling time, rise time, and overshoot, of the X-axis and Y-axis, respectively.