Stable Control Method Research Articles

Fast and Stable Control Method for a Boost-forward DC-DC Converter

Fast and Stable Control Method for a Boost-forward DC-DC Converter

A high maneuvering motion strategy and stable control method for tandem twin-rotor aerial-aquatic vehicles near the water surface

The maneuverability and stealth of aerial-aquatic vehicles (AAVs) is of significant importance for future integrated air-sea combat missions. To improve the maneuverability and stealth of AAVs near the water surface, this paper proposed a high-maneuverability skipping motion strategy for the tandem twin-rotor AAV, inspired by the motion behavior of the flying fish to avoid aquatic and aerial predators near the water surface. The novel tandem twin-rotor AAV was employed as the research subject and a strategy-based ADRC control method for validation, comparing it with a strategy-based PID control method. The results indicate that both control methods enable the designed AAV to achieve high stealth and maneuverability near the water surface with robust control stability. The strategy-based ADRC control method exhibits a certain advantage in controlling height, pitch angle, and reducing impact force. This motion strategy will offer an inspiring approach for the practical application of AAVs to some extent.

Gradient‐Strained Van Der Waals Heterojunctions for High‐Efficient Photodetectors

AbstractMaximizing light‐to‐electricity conversion efficiency is a crucial challenge for the practical applications of 2D material photodetectors. However, due to the lack of stable and precise electronic structure control methods for 2D materials, the driving force of photogenerated carriers is insufficient that severely hinders the efficiency of separation and transport. Herein, a gradient‐modulated, stable and precise strain applied strategy for 2D materials is designed and constructed, which results in a significant improvement in the detect efficiency of ZnO/WSe2/graphene van der Waals heterojunction photodetectors. Different from the overall strain of all‐component materials in typical photodetectors, biaxial tensile strain is applied to WSe2 that can be precisely modulated by controlling the height of ZnO nanorods, while the strain is nearly unaffected to ZnO. As the strain modulation increases from 1.3% to 4.0%, the external quantum efficiency (EQE) of the heterojunction increases from 11.4% to 35.3%, representing a threefold increase. Furthermore, with increasing strain, the EQE can reach higher levels. Moreover, the strain‐enhanced conversion efficiency mechanism is elucidated that results from the synergistic effect of the strain‐induced WSe2 exciton convergence and the strain‐increased ZnO/WSe2 interface barrier, which enhances the carrier interface separation efficiency.

Reinforcement learning-based stable jump control method for asteroid-exploration quadruped robots

Unlike the spherical gravitational field of planets and other large solar system bodies, the gravitational field of asteroids is irregular and weak. It is challenging for a planetary rover to obtain sufficient traction forces in this environment. However, this gravitational environment is suitable for legged robots with jumping ability, but it also imposes higher demands on control methods. Therefore, this study aimed to address the problem of jump control method for asteroid-exploration quadruped robots. As the robot jumps off the surface of an asteroid, it would fly for a certain amount of time because of the low gravitational acceleration. The prolonged flight phase underscores the significance of the robot's take off and attitude control. A model-free stable jumping control method was devised in this study. This method can satisfy the control requirements for takeoff, attitude adjustment, and soft landing by using end-to-end multi-agent reinforcement learning (MARL). MARL is more advantageous than single-agent reinforcement learning in dealing with composite motion control problems under similar observation conditions. A simulated training environment was established, incorporating models of the gravitational field, task partitioning for jumping, and design of reward functions, including jump trajectory planning. The efficacy of the proposed jump control method for a quadruped robot was successfully demonstrated in the gravitational environment of an irregular rod-shaped asteroid, 216 Kleopatra.

A stable control method for planar robot with underactuated constraints via motion planning and intelligent optimization

For the planar robot with underactuated constraints, a stable control method is presented on the foundation of motion planning method and intelligent optimization, which includes two stages. (1) Designing the controllers to control the actuated manipulators to given target states. (2) Planning the motion trajectory combined with the underactuated constraints between all links, using the intelligent algorithm to find the adaptable trajectory parameters, and tracking such planned trajectories to control full manipulators to the given states simultaneously. At last, multigroup simulations demonstrate the validity of the proposed method.

A General Stable Control Method for R-Type Underactuated Robot with Three Different Initial Situations

In this paper, we propose a general control method via the intelligent algorithm for a planar R-type underactuated robot. This control method solves the unified control problem of R-type underactuated manipulator. Meanwhile, the proposed method is also applicable to cases of nonzero initial velocity and interference rejection. Our total control program includes two stages. In the first stage, we design the trajectory based on the states of the actuated link, and then the controller is designed to track the planned trajectory to realize the objective of the actuated link. In the second stage, the trajectory with adjustable parameters is planned for the actuated link. Then, the adjustable parameters are calculated by the intelligent algorithm based on the underactuated constraints. Subsequently, the controller is designed to track the second trajectory to realize the objective of the actuated manipulator and the underactuated manipulator. Finally, the performance of the proposed method is verified through simulations.

A New Optimal Design of Stable Feedback Control of Two-Wheel System Based on Reinforcement Learning

<div>The two-wheel system design is widely used in various mobile tools, such as remote-control vehicles and robots, due to its simplicity and stability. However, the specific wheel and body models in the real world can be complex, and the control accuracy of existing algorithms may not meet practical requirements. To address this issue, we propose a double inverted pendulum on mobile device (DIPM) model to improve control performances and reduce calculations. The model is based on the kinetic and potential energy of the DIPM system, known as the Euler-Lagrange equation, and is composed of three second-order nonlinear differential equations derived by specifying Lagrange. We also propose a stable feedback control method for mobile device drive systems. Our experiments compare several mainstream reinforcement learning (RL) methods, including linear quadratic regulator (LQR) and iterative linear quadratic regulator (ILQR), as well as Q-learning, SARSA, DQN (Deep Q Network), and AC. The simulation results demonstrate that the DQN and AC methods are superior to ILQR in our designed nonlinear system. In all aspects of the test, the performance of Q-learning and SARSA is comparable to that of ILQR, with some slight improvements. However, ILQR shows its advantages at 10 deg and 20 deg. In the small deflection (between 5 and 10 deg), the DQN and AC methods perform 2% better than the traditional ILQR, and in the large deflection (10–30 deg), the DQN and AC methods perform 15% better than the traditional ILQR. Overall, RL not only has the advantages of strong versatility, wide application range, and parameter customization but also greatly reduces the difficulty of control system design and human investment, making it a promising field for future research.</div>

DC-link oscillation suppression method based on q-axis voltage compensation of a 180 kW PMSM traction system for urban rail transit

Under certain working conditions, the permanent magnet synchronous motor (PMSM) traction system of urban rail transit shows negative impedance characteristics, which is easy to cause voltage resonance of DC-link and lead to instability of the system. In order to ensure the stability of the system, a DC-link oscillation suppression method based on q-axis voltage compensation is proposed. Firstly, the PMSM traction system and oscillation mechanism of DC-link are analyzed. Secondly, a stable control method based on q-axis feedforward decoupling voltage compensation is adopted to realize the decoupling control of PMSM and the suppression of DC-link oscillation. Finally, the method is verified on a 180 kW PMSM traction system, simulation and experiment verify the effectiveness of the DC-link oscillation suppression method.

A Stability and Safety Control Method in Robot-Assisted Decompressive Laminectomy Considering Respiration and Deformation of Spine

Robot-assisted decompressive laminectomy is a new strategy in clinical applications. However, a stable contact force between the bone-cutting device and lamina is needed to keep it working correctly, which may be affected by respiration and deformation. The surgeon can adapt to this dynamic process quickly, but the robot could cause a considerable force that may damage the patient. This paper proposes a compensation control method based on a respiration-spine model to first improve the stability of the contact force. The model is established based on human morphology and ventilator parameters for anaesthetised patients. The control method is a combination of a surgery sleeve and active fuzzy control to improve the robustness of the robot. The control of the sleeve is related to the thickness of the bone layer, which can be calculated from the image. Furthermore, the lower boundary of the lamina in the CT image is extracted as a safety constraint that can protect the spinal nerves. Finally, an experiment is conducted to verify the safety constraint and compare the changes in contact force with or without the control method. The statistical experiment shows that the control error is 2.47 N without the force control method, while the force control error is 0.223 N when the target control force is 2 N. The robot will hover on the surface of the spine after completing the laminectomy of the planned area. These results show that the robot can be controlled safely and stably. Note to Practitioners—The purpose of this paper is to propose a stable and safe control method for lamina grinding robots under the influence of breathing and deformation factors. Most previous research only considered one of the two factors, and both factors are considered in this paper. Unlike the surgeon, who has the ability to adapt to physiological movements, the robot may cause a considerable force to be exerted on the device, which may damage the patient. Therefore, a controller based on human experience is longitudinally designed, and position constraints are added in three directions. This application can improve the stability and safety of robot-assisted surgery, which may be suitable for remote surgery and can help rural areas solve the problem of a lack of medical resources. Spinal model bone experiments have been completed and will be tested on animals in the future.

The Appearance of Cocoa Clones Tolerant to Infection Phytophthora palmivora

Cocoa pod rot (PBK) is the main disease that attacks cocoa pods caused by P. palmivora. Fruit rot disease causes loss of cocoa yield. Cocoa pod rot disease caused by P. palmivora pathogen is not a good and stable control method. One strategy that can be used for control is to develop superior clones tolerant of P. palmivora. Breeding program to obtain P. palmivora tolerant cocoa clones by utilizing cocoa genetic resources derived from potential cultivated clones through detached pot test. The study aimed to obtain cocoa pods tolerant of pod rot using the detached pod test. The research was conducted at the Phytopathology Laboratory of the Department of Plant Pests and Diseases, Faculty of Agriculture, Andalas University. The tested cocoa clones consisted of 6 clones, e.g., Sca 12, TSH 858, ICS 60, GC 7, K TSH 858, and K ICS 60. Cocoa clones were collected from a cocoa plantation owned by PT. Host Sari Lubuk Basuk-Agam Regency. The observed variables related to P. palmivora tolerant cocoa clones were; incubation period, growth of cacao fruit spot area, and color of cocoa beans. The results showed that the TSH 858 and ICS 60 clones had an incubation period of 3 DAI, while the Sca 12, ICS 60, GC 7, K TSH 858, and K ICS 60 clones had an incubation period of 2 DAI. The TSH 858 clone grew 10.82 cm2.day 1, while the ICS 60, GC 7, K. TSH 858 and K. ICS 60 clones grew in spot area, respectively; 11.42, 12.95, 13.24 and 13.58 cm2.day-1. TSH 858 clone has potential as a tolerant clone to P. palmivora attack through detached pod test on fruit.

Research on efficient and stable control of EUV-induced hydrogen plasma

We use the numerical model to study the control method for the ion sputter flux and energy at the surface of multilayer mirrors in hydrogen plasmas induced by extreme ultraviolet (EUV) radiation. This plasma is generated via photoionization by EUV photons with wavelengths at 13.5 nm and collision ionization by high-energy electrons. An electric field is formed by applying different bias voltages to the cylindrically symmetrical cavity and sample holder, which guides the transfer of charged particles and increases their energy. The evolution of pulsed EUV-induced plasma under the field is described by a two-dimension particle-in-cell model and the Monte Carlo simulation to represent collisions between charged particles and background molecules. The results show that the distribution of the electric field varies during the pulse and point out that the secondary electrons, which gain energy from the varying field and generate more plasma by collisions with hydrogen molecules, are crucial plasma sources in this scheme. We then propose a stable and efficient control method for EUV-induced hydrogen plasma by optimizing the cavity structure as an ellipsoid and treating the surface of the cavity in contact with the plasma.

Modeling analysis, control, and type-2 fuzzy energy management strategy of hybrid fuel cell-battery-supercapacitor systems

In this paper, dynamic modeling analysis and a stable control method are presented for the hybrid energy storage systems (HESS) including the fuel cell (FC), battery (BA), and a supercapacitor (SC). First, based on the dynamical behavior of power sources, a filtered dynamical model of the DC-DC converters is presented. The objective of the suggested scheme is to avoid rapid changes in the dynamic response of power sources. Next, a robust observer-based control method is presented to obtain a stable voltage of the DC-bus and provide proper performance of the energy sources. Finally, a type-2 fuzzy algorithm is proposed for the energy management system (EMS) of the HESS. It can provide reliable situations to compensate for knowledge-based uncertainties of the fuzzy rules. The stability of the proposed method is provided by the Lyapunov approach to ensure the asymptotic stability of the closed-loop systems under the various levels of uncertainties. To show the performance and efficiency of this work, the proposed strategy is used to control a hybrid tramway including FC, battery, and SC.

Propellant-free attitude control of solar sails with variable-shape mechanisms

Solar sails can realize propellant-free attitude control if they have the ability to change their shape by moving reflective surfaces to harness the force of incident solar radiation pressure (SRP). In this paper, we formulate a stability analysis of the attitude motion of a sail spacecraft with large deformation under SRP, and propose stable attitude control methods using variable-shape mechanisms. The basic principle is that the attitude is maintained at a stable equilibrium point that suppresses the disturbance torque due to SRP and prevents disturbance angular momentum from accumulating in the reaction wheels. The equilibrium point can be shifted by moving reflective surfaces, and the attitude follows the new equilibrium point by reaction wheel control. The stability of the equilibrium points can be quickly evaluated by a stability analysis based on linearized equations of motion, and one can choose any equilibrium point by setting the reflective surfaces to a corresponding configuration. This control scheme enables the spacecraft body to be pointed towards desired directions, and even if the attitude maneuver and maintenance accumulate angular momentum in the reaction wheels, this momentum can also be unloaded without propellant by using SRP and shape variation. The dynamics formulation aims at a zero-momentum system that is generally applicable to arbitrarily shaped spacecraft, and the formulation of the stability analysis and control methods were verified by numerical simulations.

Humanoid Biped Robot Locomotion via Quadratic Programming with Compound Constraints

This paper introduces a quadratic programming-based stable motion control method for humanoid robots. This method is based on the virtual model and the optimal force distribution. We added a six-dimensional mixed constraint on the sole of the foot to prevent the robot from sliding and overturning. At the same time, a more comprehensive swing planning and pre-touchdown planning were added when the robot's legs were swinging to improve the stability of the robot's walking on the ground. Finally we verified the algorithm in the robot simulation software and proved the feasibility of the algorithm.

Research on Stable Motion Control Method of Underwater Robot Based on Collaborative Filtering Technology

As countries in the world continue to deepen marine research and development and the need for national defense construction, unmanned underwater robots are playing an increasingly important role in scientific experiments, seabed oil and gas exploration and testing, and military affairs. The motion stability of underwater robots is the key to ensure the safe and reliable operation of underwater robots, and it is the main content of stability control research to make underwater robots return to the initial state of motion after being disturbed. Therefore, it becomes very important to study stability control methods. It’s necessary. This thesis first analyzes the motion characteristics of collaborative filtering technology in water, and establishes a dynamic model of an underwater robot system composed of main thrusters, double vertical thrusters and double-sided thrusters, and performs basic fluid flow for underwater robots.

Long-term stable operation control method of dual-battery energy storage system for smoothing wind power fluctuations

Since wind output power shows obvious fluctuations characteristics, direct grid-connection will bring great challenges to the safe and stable operation of the power system. In order to achieve better economic benefits, this paper adopts the dual-battery energy storage system (DBESS) operation mode which performs charge–discharge tasks separately considering the discharge depth and frequent charge–discharge conversion on battery life. However, the extreme operation will occur when considering the imbalance of charge and discharge energy of DBESS, which will make it difficult for DBESS to maintain long-term stable operation to smooth the wind output power. Besides this paper proposes a charge–discharge operational stability index for characterizing the system operation status, based on the real-time operating conditions of the energy storage system and wind power fluctuations. To ensure the DBESS long-term operation stability, the extreme operation problems caused by charge–discharge unbalanced energy in the long-term operating process must be solved. This paper used two proposed indicators as input factors and proposed a control strategy to adaptively fine-tune the first-order low-pass filtering time constant, to charge the battery throughput power in real-time and optimize two battery packs’ State of Charge (SOC). The effectiveness of the proposed control strategy is verified from two aspects by using MATLAB/Simulink software: the SOC optimizing control effect and the power fluctuation smoothing effect.

Design and analysis of a lower extremity exoskeleton with the humanoid knee joint

Exoskeletons should have certain capabilities and characteristics such as human performance enhancement, low impedance and comfortable. In this paper we present a lower extremity exoskeleton. In order to achieve the characteristics of exoskeletons mentioned above we choose the Series Elastic Actuator (SEA) as its driver. A novel humanoid knee joint is introduced into the exoskeleton to improve the coordination between exoskeleton and human body during work progress. A stable control method is proposed to achieve the exoskeleton joint following motion. Finally, the feasibility of control algorithm is verified by simulation.

BIBO-stable implementation of adaptive function expansion bilinear filter for nonlinear active noise control

The preeminent merit of function expansion bilinear (FEB) filters is their ability to represent nonlinear distributions for active noise control (ANC) systems. Unfortunately, the huge computational burden and bounded input bounded output (BIBO) unstable problem hinder its practical applications. In this paper, we propose a general channel reduced efficient implementation algorithm for FEB filter and two BIBO stable control methods, to further reduce the computational load and overcome the unstable problem. The efficiency of the proposed methods is verified by computational complexity analyses and computer simulations for nonlinear ANC (NANC) systems. The results of computational analysis and computer simulation show the satisfied control performances with significant computational reduction.

Nonsingular terminal sliding mode controller for voltage and current control of an islanded microgrid

This paper presents a robust and effective method for voltage and current control of an islanded microgrid. The effects of external disturbances and parametric uncertainties pose challenges in voltage and current control of islanded microgrids. Therefore, adopting a robust and stable control method is imperative. Nonsingular terminal sliding mode controller (NTSMC) which is a subset of sliding mode controllers (SMC) is proposed in this paper to control the voltage. Moreover, NTSMC is robust against a wide variety of uncertainties and external disturbances. Unlike conventional SMC, NTSMC ensures finite time convergence to the equilibrium point. The proposed control method was implemented in Matlab/Simulink, and its performance was evaluated under different loads and parametric uncertainties in the presence of external disturbances. Simulation results show the desirable performance of the proposed controller in maintaining stability of the islanded microgrid with precise voltage and current control against significant uncertainties and external disturbances.

Fuzzy-backstepping control of quadruped robots

In this paper, fuzzy-backstepping control method is utilized to control quadruped robots. The backstepping control method is inherently a stable control method since its design procedure is based on the Lyapunov stability theory. However, for an acceptable performance of this controller, the feedback gains must be appropriately selected. Using fuzzy systems, these gains are adaptively tuned for best performance of the robot against uncertainties in system parameters, external disturbances, and measurement noises. Next, the stability of the robot is investigated using the Poincare map stability criterion. This is because the Lyapunov method does not guarantee stability for the periodic systems such as legged robots. The proposed method is simulated on the highly nonlinear equations of a quadruped robot. The performance of the proposed method is compared with the backstepping control to show the importance of fine-tuning the parameters using fuzzy system. The simulating results for a nine-degree-of-freedom quadruped robot show very good performance of the proposed control method, especially against uncertainties in system parameters, external disturbances, and measurement noises, which are common in robots.