Current Issue

  • Regular PapersApril 1, 2024

    Interval Reduced-order Switched Positive Observers for Uncertain Switched Positive Linear Systems

    Naohisa Otsuka*, Daiki Kakehi, and Przemysław Ignaciuk

    International Journal of Control, Automation, and Systems 2024; 22(4): 1105-1115

    https://doi.org/10.1007/s12555-023-0103-6

    Abstract

    Abstract : In this paper, existence conditions and a design procedure of reduced-order switched positive observers for continuous- and discrete-time switched positive linear systems with uncertainty are established. In the analyzed class, arbitrary switching is permitted, whereas the uncertainty expressed via matrix inequalities concerns both the initial state and system parameters. Positive lower and positive upper interval switched observers are obtained. The proposed observers are of (n− p) order, where n is the dimension of the state vector and p is the rank of the output matrix, i.e., p-dimensional measurement information. Moreover, as a special case, existence conditions and a design procedure of reduced-order positive observers for uncertain positive linear systems without switching are provided. The theoretical findings are illustrated by two numerical examples for continuous- and discrete-time systems.

  • Regular PapersApril 1, 2024

    Robust Output Tracking Control of Uncertain Nonaffine Systems With Guaranteed Tracking Error Bounds

    Zhixiang Chen, Wenyan Bai*, and Lingjian Kong

    International Journal of Control, Automation, and Systems 2024; 22(4): 1116-1128

    https://doi.org/10.1007/s12555-021-0974-3

    Abstract

    Abstract : This paper considers the output tracking problem for uncertain nonaffine systems. A robust output tracking controller for a class of uncertain nonaffine strict-feedback systems with guaranteed tracking error bounds is proposed. First, a diffeomorphism is employed to convert the strict-feedback nonaffine system with mismatched uncertainties into a feedback linearization nonaffine system (FLNS). Second, for the transformed FLNS, an error transformation and sliding surface technique are combined to transform the constrained tracking problem of a highorder system into an unconstrained stabilization problem of a first-order system when visualizing the guaranteed tracking error bound as a tracking error constraint. Then, a saturated approximate dynamic inversion scheme and an extended state observer are combined to achieve the stabilization of the transformed first-order nonaffine system. The stability of the closed-loop system is analyzed rigorously and it is sufficient to guarantee that the tracking error constraint can be achieved and all system states are semi-globally uniformly bounded for the original system. Simulation results clarify and verify the effectiveness of the proposed method.

  • Regular PapersApril 1, 2024

    Robust Positive Consensus for Heterogeneous Multi-agent Systems

    Ruonan Li, Yutao Tang, and Shurong Li*

    International Journal of Control, Automation, and Systems 2024; 22(4): 1129-1137

    https://doi.org/10.1007/s12555-022-1201-6

    Abstract

    Abstract : This paper investigates a robust positive consensus problem for a class of heterogeneous high-order multi-agent systems subject to external inputs. Compared with existing multi-agent consensus results, the most distinct feature of the formulated problem is that the state variables of all heterogeneous agents are confined in the positive orthant. To solve this problem, we present a two-step design procedure. By constructing an auxiliary multi-agent system as positive local reference generators, we incorporate the reference generator into an applicable decentralized robust tracking controller for each agent. The proposed distributed algorithm is proven to ensure a robust consensus fulfilling certain prescribed pattern for the multi-agent system under switching topology in the sense of finite-gain stability with respect to the external inputs. A simulation example is finally given to illustrate the effectiveness of our design.

  • Regular PapersApril 1, 2024

    Event-triggering Formation Control for Second-order Multi-agent Systems With Sampled Position Data

    Jing Liu*, Zhen Li, Jia-Bao Liu, and Jian-an Fang

    International Journal of Control, Automation, and Systems 2024; 22(4): 1138-1149

    https://doi.org/10.1007/s12555-022-0165-x

    Abstract

    Abstract : This paper addresses the problem of event-triggering formation control (ETFC) for second-order multiagent systems (MASs) with sampled position data. Firstly, two types of distributed control strategies based on the sampled position data are proposed to solve the observer-based formation control problems. These novel formation control strategies allow the event-triggering conditions to be intermittently examined at random sampling instants, where the data transmission is driven by an event-triggering control protocol. Under this framework, both timeinvariant and time-varying formation controls are considered. Then, based on the algebraic graph theory and matrix theory, some sufficient conditions are given to ensure that the second- order MASs achieve the specified formation shape. Finally, simulation results are provided to show the effectiveness of the theoretical analysis.

  • Regular PapersApril 1, 2024

    Stochastic Consensus for Heterogeneous Multi-agent Networks With Constraints and Communication Noises

    Haokun Hu, Lipo Mo*, and Fei Long

    International Journal of Control, Automation, and Systems 2024; 22(4): 1150-1162

    https://doi.org/10.1007/s12555-022-1055-y

    Abstract

    Abstract : The mean-square consensus of the discrete-time heterogeneous multi-agent systems (HMASs) with convex position constraints, nonconvex velocity constraints and communication noises is reported in this paper, where the dynamics of HMASs are composed of first-order or second-order difference equations, and the noises are assumed to be martingale difference sequences. Firstly, a new algorithm is designed based on the information from neighbor agents with noises, and the original system is changed into an equivalent one by introducing a coordinate transformation. Secondly, when the communication graph is joint strongly connected, it is proved that mean-square consensus can be achieved by the properties of stochastic matrix, projection operator and martingale, and the position and velocity states of agents stay at the corresponding constraint sets. Specially, the situations of a network containing only first-order agents or second-order agents are considered, respectively. Finally, the correctness of the theoretical results is verified by numerical simulations.

  • Regular PapersApril 1, 2024

    Robust Control for Bidirectional Stabilization System With Time Delay Estimation

    Shu-sen Yuan, Wen-xiang Deng*, Jian-yong Yao, and Guo-lai Yang

    International Journal of Control, Automation, and Systems 2024; 22(4): 1163-1175

    https://doi.org/10.1007/s12555-022-0807-z

    Abstract

    Abstract : In this paper, to address the problem of high precision tracking control for bidirectional stabilization system of marching all-electric tank, a continuous nonsingular terminal sliding mode (CNTSM) control method combined with time delay estimation (TDE) technique is presented. First, the nonlinear mathematical model of the bidirectional stabilization system with consideration of actuator dynamics is established. Second, the TDE method is invoked to estimate the unknown system dynamics and provide fascinating model-free structures. Then, a CNTSM surface and a fast TSM reaching law are constructed to guarantee finite-time convergence. The proposed controller no longer requires system dynamics benefiting from TDE, while ensuring high accuracy, fast convergence and good robustness against lumped uncertainty due to the CNTSM manifold and the fast TSM reaching law. The stability and finite-time convergence of the closed-loop system are analyzed applying Lyapunov theory. Extensive comparative results verify the superiority with the proposed controller.

  • Regular PapersApril 1, 2024

    Dynamic Event-triggered Distributed Observer Based Output Regulation of Heterogeneous Multi-agent Systems

    Kairui Chen, Zhangmou Zhu, Xianxian Zeng, and Jianhui Wang*

    International Journal of Control, Automation, and Systems 2024; 22(4): 1176-1185

    https://doi.org/10.1007/s12555-023-0013-7

    Abstract

    Abstract : In this paper, the output regulation problem for heterogeneous linear multi-agent systems is investigated, where each agent suffers from the detectability deficiency problem. Specifically, each agent has access to only partial output information of the exosystem, which bring about challenges to estimate full states of the exosystem. By using the observability decomposition technique, unobservable states in each agent are extracted. Then, a kind of distributed observer with dynamic event-triggered mechanism is developed to estimate full states of the exosystem for each agent cooperatively. Besides, the Zeno behavior is voided strictly when executing the event-triggered strategy. Furthermore, the distributed observer is employed to solve the output regulation problem of heterogeneous multi-agent systems based on the feedforward output regulation technique. Finally, a numerical example is conducted to verify the correctness of the proposed control algorithm.

  • Regular PapersApril 1, 2024

    Robust Fault Detection Scheme for Asynchronous Switched Systems via Sliding Mode Observer

    Shafqat Ali, Yuchen Jiang*, Hao Luo*, Muhammad Taskeen Raza, Shah Faisal, and Faizan Shahid

    International Journal of Control, Automation, and Systems 2024; 22(4): 1186-1200

    https://doi.org/10.1007/s12555-023-0121-4

    Abstract

    Abstract : This work studies the fault detection problem for continuous-time asynchronous switched systems. For residual signal generation, we design a fault detection sliding mode observer such that residual characterizes the fault sensitivity level by H_ performance, and its robustness to process disturbance is determined by H∞ performance. Specifically, the challenge entails addressing the phenomenon of asynchronous switching between the controlled object and the observer, where there is a delay between the switching of the subsystems and the observer. A piece-wise Lyapunov function and average dwell time approach are applied to resolve the asynchronous switching stability within matched and unmatched periods. A feasible solution is derived based on linear matrix inequalities. For effective fault detection, a residual evaluation scheme is provided with a threshold. Finally, simulation results on a buck-boost converter are furnished to validate the usefulness of the proposed approach.

  • Regular PapersApril 1, 2024

    Practical Tracking Control for High-order Nonlinear Systems With Dynamic Uncertainties and Unknown Powers via Event-triggered Mechanism

    Jiling Ding, Weihai Zhang*, and Junsheng Zhao

    International Journal of Control, Automation, and Systems 2024; 22(4): 1201-1211

    https://doi.org/10.1007/s12555-022-1248-4

    Abstract

    Abstract : This paper studies the problem of output regulation for a class of high-order nonlinear systems with dynamic uncertainties and unknown powers. Based on the characters of input-to-state stable Lyapunov function and the technique of changing supply rate, a partial-state feedback controller is designed under event-triggered mechanism framework. In the proposed control law, an adaptive dynamic gain is constructed to deal with system uncertainties and eliminate the bad effect of the event-triggered sampling error, and a term of higher power is introduced to compensate the unknown system powers. It is verified that the output tracking error converges into any prescribed small set of the origin and all the closed-loop signals are globally bounded by the proposed partialstate feedback controller, while the Zeno phenomenon is avoided. The effectiveness of the proposed scheme is verified by some simulation results.

  • Regular PapersApril 1, 2024

    Hedonic Coalition Formation for Distributed Task Allocation in Heterogeneous Multi-agent System

    Lexing Wang, Tenghai Qiu*, Zhiqiang Pu, Jianqiang Yi, Jinying Zhu, and Wanmai Yuan

    International Journal of Control, Automation, and Systems 2024; 22(4): 1212-1224

    https://doi.org/10.1007/s12555-022-1182-5

    Abstract

    Abstract : Due to the complexity of tasks in the real world, multiple agents with different capabilities tend to cooperate to handle diverse requirements of these tasks by forming coalitions. To solve the problem of finding optimal heterogeneous coalition compositions, this paper proposes a novel distributed hedonic coalition formation game method to solve the task allocation problem for multiple heterogeneous agents. Firstly, to quantify the intention of an agent joining each coalition, a utility function for each agent is designed based on the cost and the reward with regard to the given tasks, where the heterogeneous requirements of tasks are also considered. Then, a preference relation related to the utility function is designed for the self-interested agents autonomously choose to join or leave a coalition. Subsequently, a theorem is presented, and analyses have been conducted to show that the proposed method achieves a Nash-stable solution in the heterogeneous system. Further, to develop a Nash stable partition result, a distributed hedonic coalition formation algorithm containing prioritization and consensus stages is designed for each agent to make decisions. The algorithm is implemented based on local interactions with neighbor agents under a connected communication network. Finally, simulations are conducted to verify the performance of the proposed method. Results show that the proposed method has the feasibility in solving heterogeneous composition and the broader scalability in different scenarios.

  • Regular PapersApril 1, 2024

    Nonlinear Robust Adaptive Control of Electro-hydrostatic Actuators With Continuous Friction Compensation

    Jiahui Liu, Jianyong Yao*, and Wenxiang Deng

    International Journal of Control, Automation, and Systems 2024; 22(4): 1225-1237

    https://doi.org/10.1007/s12555-022-1120-6

    Abstract

    Abstract : Electro-hydrostatic actuators (EHAs) have gradually been applied in the flight control systems of multielectric/all-electric aircraft due to the high power-to-volume ratio and the absence of throttling loss as well as overflow loss. However, the existence of high-order dynamics, system nonlinearities, and uncertainties significantly limits the tracking performance of EHAs. This article developed a robust adaptive controller with continuous friction compensation to improve the precise control performance of an EHA with a variable load, nonlinear friction, parametric uncertainties, and unmodeled disturbances. A nonlinear robust control law is used to attenuate various disturbances, and an adaptive law is adopted to cope with parametric uncertainties. Additionally, a continuous friction model is used to describe the friction behavior of an EHA to achieve effective friction compensation and further enhance the motion performance. Moreover, the upper bounds of the matched and mismatched uncertainties can be updated in real-time via adaptive laws, which can reduce design conservatism to some degree. The Lyapunov stability analysis reveals that asymptotic performance can be guaranteed despite the presence of unmodeled disturbances and parametric uncertainties. Furthermore, the applicability of the designed control algorithm with continuous friction compensation is demonstrated with experimental results.

  • Regular PapersApril 1, 2024

    Time-optimal and Smooth Trajectory Planning for Multi-axis Motion Systems Based on ISC Similarity

    Tie Zhang*, Jia Cheng, and Yanbiao Zou

    International Journal of Control, Automation, and Systems 2024; 22(4): 1238-1251

    https://doi.org/10.1007/s12555-022-1082-8

    Abstract

    Abstract : Aiming at time-optimal smooth trajectory planning for multi-axis motion systems, this paper proposes a planning algorithm based on improved sqrt-cosine (ISC) similarity in the phase plane. The improved sqrt-cosine similarity algorithm and the kinematic constraint of the interpolated trajectories are used to find the time-optimal smooth trajectory. In the proposed algorithm, the trajectory of the multi-axis motion system workbench is represented by scalar path coordinates. And it is re-discretized by adjusting the spacing of the discrete points several times to obtain trajectories with different numbers of discrete points. The corresponding time-optimal trajectories in the phase plane are planned through a numerical integration-like algorithm. The similarity between the timeoptimal trajectories is then compared using an improved sqrt-cosine similarity algorithm to find the trajectories with high similarity. Finally, the time-optimal smooth trajectory is obtained by the acceleration constraint of the interpolated trajectory. Experiments on a two-axis motion system have shown that the time-optimal trajectory planned by the proposed algorithm satisfied the constraints of dynamics and kinematics, effectively reduced the planning calculation time, and obtained a smooth trajectory. In experiments, compared with numerical integration-like timeoptimal trajectory planning algorithm, the maximum accelerations in the Z-axis, X-axis, and vertical directions of the two-axis motion system have been reduced by 37.66%, 11%, and 31.42%, respectively.

  • Regular PapersApril 1, 2024

    Finite-time Secondary Frequency Modulation of Microgrid Based on Event Triggering Mechanism

    Chenglong Zhou, Ze Li* , Guozeng Cui, Yifan Chen, and Wangjun Hao

    International Journal of Control, Automation, and Systems 2024; 22(4): 1252-1263

    https://doi.org/10.1007/s12555-021-1096-7

    Abstract

    Abstract : This paper designs a ratio consistency algorithm based on event triggering mechanism aiming at the frequency recovery deviation caused by traditional droop control in microgrid. It achieves secondary frequency modulation in microgrid by adjusting the active power setting value. The max-min consistency algorithm is proposed to realize asymptotic consistency of distributed power supply in a finite time. Communication delay is added to ensure the accuracy of frequency update and verifies the robustness of the algorithm against itself. Meanwhile, the validity of event triggering conditions is verified. Finally, the simulation examples are carried out to prove the correctness and superiority of the proposed finite-time control strategy.

  • Regular PapersApril 1, 2024

    Maritime Targets Tracking in Heavy-tailed Clutter With Unknown and Time-varying Density

    Liwei Shi*, Yu Kuang, and Miaomiao He

    International Journal of Control, Automation, and Systems 2024; 22(4): 1264-1276

    https://doi.org/10.1007/s12555-022-0638-y

    Abstract

    Abstract : In order to solve the problem of maritime targets tracking in heavy-tailed sea clutter with unknown and time-varying clutter density, a multi-scan clutter sparsity estimator based amplitude-aided probability hypothesis density (MCSE-APHD) method is proposed in this paper. Firstly, the proposed method eliminates the targetoriginated measurements from multi-scan cumulative measurement set and estimates the spatial distribution density of clutter online. And the estimated clutter density parameter is fed to the tracker. Secondly, the amplitude-aided likelihood function as well as the estimated clutter parameter is established to update the Gaussian mixture posterior intensity of the state using the probability hypothesis density algorithm. The simulation results verify the effectiveness of the proposed algorithm.

  • Regular PapersApril 1, 2024

    A Novel Rate-dependent Direct Inverse Preisach Model With Input Iteration for Hysteresis Compensation of Piezoelectric Actuators

    Yutong Sun, Haifeng Ma*, Yangmin Li, Zhanqiang Liu, and Zhenhua Xiong

    International Journal of Control, Automation, and Systems 2024; 22(4): 1277-1288

    https://doi.org/10.1007/s12555-022-1024-5

    Abstract

    Abstract : This paper proposes the design and validation of a novel rate-dependent direct inverse Preisach model with input iteration (RDIPMII) dedicated to feedforward compensation of hysteresis nonlinearity in piezoelectric
    actuators (PEAs). Unlike existing similar works, the proposed RDIPMII avoids deriving the parameters of the inverse compensator from the hysteresis model, and could be directly employed as the inverse compensator. Furthermore, RDIPMII is capable of achieving rate-dependent inverse compensation while reducing the experimental burden in identifying models by the use of newly proposed data expression method (DEM). In addition, by integrating iterative learning control (ILC), RDIPMII accomplishes online input iteration to further suppress the hysteresis effect. The feasibility and efficiency of the presented scheme are demonstrated through experimental investigations conducted on a PEA.

  • Regular PapersApril 1, 2024

    A Novel Approach to Coupling Terms to Avoid Obstacles in a Manipulator Movement Reproduction

    Byung Su Kim and Min Cheol Lee*

    International Journal of Control, Automation, and Systems 2024; 22(4): 1289-1300

    https://doi.org/10.1007/s12555-023-0419-2

    Abstract

    Abstract : Many people have attempted to generate specific movements based on the concept that neural networks in the brain and spinal cord create multiple sets of temporal templates. Dynamic movement primitives (DMPs) are inspired by the motion control of biological systems and can be mathematically represented as stable nonlinear dynamic systems in the form of motion primitives. One way to improve the work efficiency of robots in various industries is to leverage the ability of DMPs to generalize learned trajectories to enable them to perform a wider range of tasks. This study discusses obstacle avoidance techniques using DMPs and proposes a novel approach to obstacle avoidance. DMPs have the ability to generalize and have extensions that make them valuable in generalizing in unforeseen situations. Obstacle avoidance in DMPs has been approached in various ways, with previous research utilizing potential field methods as typical obstacle avoidance techniques. We added a formulated coupling term to DMPs to avoid obstacles. This novel approach proposes modeling obstacles as point clouds, objects surrounded by bounding boxes or smooth standard shapes, and adding a new coupling term to smoothly avoid obstacles without disrupting the existing reference movement’s topology while closely following a reference trajectory. This study also discusses the determination of the magnitude and direction of a desired repelling force against obstacles. Overall, this study discusses obstacle avoidance techniques using DMPs and introduces a novel approach that improves obstacle avoidance in DMPs. The goal of this study is to confirm the effectiveness of the proposed approach by implementing previous and newly proposed algorithms for semi-elliptical trajectories and applying them to robot manipulators.

  • Regular PapersApril 1, 2024

    A Theoretical Conversion of Torque Controllers for Handling a Position Servo-actuated Robot Manipulator Model

    Gabriela Zepeda*, Rafael Kelly, and Carmen Monroy

    International Journal of Control, Automation, and Systems 2024; 22(4): 1301-1312

    https://doi.org/10.1007/s12555-022-1243-9

    Abstract

    Abstract : Traditional robot control theory assumes implicitly that robot manipulators are equipped with ideal torque actuators (i.e., torque-driven robots). However, it is important to note that both industrial robots and economical didactic ones do not typically feature such torque actuators. In contrast, many robotics laboratories engaged in academic and research activities employ robots equipped with position servo actuators, which do not support torque control input commands. This paper aims to bridge the gap between theory and practical implementation of robot control from an automatic control perspective. To achieve this goal, a new method is introduced for converting any torque requesting control system, designed for torque–driven robots, to be directly applied to robots using proportional embedded control with position servo actuators (servo–actuated robots lack direct torque input for control). The method relies on the inverse dynamics approach, considering the comprehensive nonlinear model of a position servo–actuated robot structure. This model encompasses servos dynamics, inheriting both the advantages and disadvantages associated with model–based control algorithms.

  • Regular PapersApril 1, 2024

    A Fault-tolerant Synchronous Sliding Mode Control for a 4-DOF Parallel
    Manipulator With Uncertainties and Actuator Faults

    Duc Thien Tran, Nguyen Thanh Nha, Ngo Van Thuyen, Le Hoang Lam, and Kyoung Kwan Ahn*

    International Journal of Control, Automation, and Systems 2024; 22(4): 1313-1323

    https://doi.org/10.1007/s12555-023-0153-9

    Abstract

    Abstract : This paper proposes a novel fault-tolerant synchronous sliding mode control for a 4-DOF parallel manipulator against uncertainties such as modelling error and actuator faults. The proposed control is developed with the consensus approach, sliding mode control, and extended state observer to manage the tracking objective and guarantee the synchronous requirements. The consensus approach combines the tracking and synchronous errors, which helps to integrate both the tracking and synchronous requirements into cross-coupling errors. Firstly, the kinematics and dynamics of the parallel manipulator are described according to the geometric and Euler Lagrange approaches with the challenges. Secondly, the Lyapunov approach is implemented to verify the stability and robustness of the proposed control in theory. Then, some simulations are conducted in MATLAB Simulink with the robotic dynamics generated by converting the design model in SOLIDWORKs into SIMSCAPE. The comparisons between the proposed control and other controllers are made by creating simulations to evaluate the advantages of the proposed approach.

  • Regular PapersApril 1, 2024

    A Path Planning Method for Unmanned Surface Vessels in Dynamic Environment

    Jiabin Yu*, Zhihao Chen, Zhiyao Zhao, Jiping Xu, and Yang Lu

    International Journal of Control, Automation, and Systems 2024; 22(4): 1324-1336

    https://doi.org/10.1007/s12555-022-1172-7

    Abstract

    Abstract : A path planning method for unmanned surface vessels (USV) in dynamic environment is proposed to address the impact of dynamic environments on path planning results and the lack of dynamic obstacle avoidance capabilities. First, the considering ocean current rapidly exploring random tree (RRT*) (COC-RRT*) algorithm was proposed for global path planning. The RRT* algorithm has been enhanced with the integration of the virtual field sampling algorithm and ocean current constraint algorithm. The COC-RRT* algorithm optimizes the global planning path by adjusting the path between the parent nodes and child nodes. Second, according to the limitations of the International Regulations for Preventing Collisions at Sea (COLREGs), the improved dynamic window approach (DWA) is applied for local path planning. To enhance the ability of avoid dynamic obstacles, the dist function in the DWA algorithm has been improved. Simulation experiments were conducted in three scenarios to validate the proposed algorithm. The experimental results demonstrate that, in comparison with other algorithms, the proposed algorithm effectively avoids dynamic obstacles and mitigates the influence of the space-varying ocean current environment on the path-planning outcome. Additionally, the proposed algorithm exhibits high efficiency and robustness. The results verified the effectiveness of the proposed algorithm in dynamic environments.

  • Regular PapersApril 1, 2024

    Planning and Execution of Dynamic Whole-body Locomotion for a Wheeled Biped Robot on Uneven Terrain

    Yaxian Xin*, Yibin Li, Hui Chai, Xuewen Rong, and Jiuhong Ruan

    International Journal of Control, Automation, and Systems 2024; 22(4): 1337-1348

    https://doi.org/10.1007/s12555-022-0866-1

    Abstract

    Abstract : To improve the adaptability of the wheeled biped robot (WBR) to uneven terrain, firstly an integrated modeling method for wheeled-legs is proposed. The under-actuated part is effectively restrained by defining the interaction force between the WBR and the trunk. The mapping relationship between the wheeled leg’s end force and the joint torques in the balanced state is built. Based on this premise, a control framework that does not rely on external sensors is proposed, and the trunk pose is used as the task space to plan the generalized force output of the wheeled legs and calculate the joint torques. Since the joint space position is not constrained, the leg wheels will be based on the terrain conditions and are adaptively stretched and adjusted back and forth. To further improve the terrain adaptability, a slope estimator and a stabilizer are constructed to deal with the attitude fluctuation caused by the sudden change of terrain. The control framework is proved to verify by simulations and experiment.

  • Regular PapersApril 1, 2024

    Distributed Formation Control for Multiple Quadrotor UAVs Based on Distributed Estimator and Singular Perturbation System

    Ning Li*, Hongbin Wang, Qianda Luo, and Wei Zheng

    International Journal of Control, Automation, and Systems 2024; 22(4): 1349-1359

    https://doi.org/10.1007/s12555-022-1157-6

    Abstract

    Abstract : In this paper, the leader-follower distributed formation control of quadrotor unmanned aerial vehicles (UAVs) with communication constraints is studied, in which the leader’s information can only be obtained by one follower quadrotor UAV. To make every follower quadrotor UAV get the leader’s information, a distributed estimator was designed for each follower to estimate the leader’s information. Therefore, the requirements of communication topology can be reduced, and the accuracy and speed of formation control can be improved under the condition of reducing the communication of quadrotor UAVs. An improved integral sliding mode control protocol is provided by introducing a multi-time scale singularly perturbed system to ensure that follower quadrotor UAVs can keep a predetermined formation while tracking the desired trajectory. Then, the stability analysis of the proposed controller is conducted using singularly perturbed and Lyapunov theory. Simulation results of different formations show that multiple quadrotor UAVs can complete formation tasks efficiently and accurately.

  • Regular PapersApril 1, 2024

    Variable Impedance Control for a Single Leg of a Quadruped Robot Based on Contact Force Estimation

    Yanan Fan*, Zhongcai Pei, and Zhiyong Tang

    International Journal of Control, Automation, and Systems 2024; 22(4): 1360-1370

    https://doi.org/10.1007/s12555-022-0601-y

    Abstract

    Abstract : A quadruped robot interacts with the ground during the stance phase. This interaction will have a great impact on the feet, torso and joints of the robot, thus affecting the stability of its movement and reducing its adaptability in complex environments with features such as uneven terrain. The contact between each foot of the quadruped robot and the ground should not only control the movement trajectory of the leg but also control the force between the leg and the ground to comply with the environmental constraints. In general, the environment is constantly changing, whereas the traditional impedance control parameters are fixed and thus impose fixed-point constraints. To improve the compliance of the feet of a robot and achieve flexible interactions with the ground in various complex environments, such as pipelines, ruins and forests, variable impedance control is proposed. Based on variable inertia, damping and stiffness parameters, a new Lyapunov function is selected to analyse the stability of the closed-loop system. Furthermore, a force estimator is applied to estimate the contact forces, thereby reducing the burden of structural design and the cost of the robot. The effectiveness of the proposed variable impedance control scheme and contact force estimator is verified through numerical simulations in MATLAB.

  • Regular PapersApril 1, 2024

    Cascade Antidisturbance Control of Hydraulically Driven Bipedal Robots for High Dynamic Locomotion by Using Model Prediction and Task Hierarchical Optimization

    Jie Huang, Huajie Hong, Nan Wang, Hongxu Ma, Honglei An, and Lin Lang*

    International Journal of Control, Automation, and Systems 2024; 22(4): 1371-1384

    https://doi.org/10.1007/s12555-021-1105-x

    Abstract

    Abstract : The development of hydraulically driven heavy legs that can withstand external interference for realizing the high-velocity dynamic walking of bipedal robots with eight degrees-of-freedom is challenging. Therefore, in this study, a cascade antidisturbance algorithm was proposed for highly dynamic trajectory tracking based on model prediction and task hierarchical optimization. First, in the upper layer, the time-sharing control framework of underactuated robots based on the single rigid body model ignoring the legs was designed. Linear model predictive control (MPC) was designed to calculate the contact force spin to control the posture and height of floating base in the stand phase. The desired foot location principle was used to control the forward and lateral velocity in the swing phase. Next, in the lower layer, task hierarchical optimization control (THOC) was designed to track the contact force spin predicted by MPC. The relaxation variable of the force spin was designed in the optimized variable and subsequently used to compensate for the contact force between single rigid body and whole-body dynamic models. Thus, the tie relationship was developed between the upper MPC and lower THOC. The control robustness of the proposed model under high-velocity locomotion and disturbance was verified by performing simulation experiments investigating high-velocity walking and external impact, and the fast walking velocity was increased from 2.15 m/s of nonlinear MPC to 2.5 m/s with accurate velocity tracking.

  • Regular PapersApril 1, 2024

    A Real-time Path Planning Algorithm for Mobile Robots Based on Safety Distance Matrix and Adaptive Weight Adjustment Strategy

    Xinpeng Zhai, Jianyan Tian*, and Jifu Li

    International Journal of Control, Automation, and Systems 2024; 22(4): 1385-1399

    https://doi.org/10.1007/s12555-022-1016-5

    Abstract

    Abstract : The fusion of the A* and the dynamic windowing algorithm is commonly used for the path planning of mobile robots in dynamic environments. However, the planned path has the problems of redundancy and low security. This paper proposes a path planning algorithm based on the safety distance matrix and adaptive weight adjustment strategy to address the above problems. Firstly, the safety distance matrix and new heuristic function are added to the traditional A* algorithm to improve the safety of global path. Secondly, the weight of the evaluation sub-function in the dynamic window algorithm is adjusted through an adaptive weight adjustment strategy to solve the problem of path redundancy. Then, the above two improved algorithms are fused to make the mobile robot have dynamic obstacle avoidance capability by constructing a new global path evaluation function. Finally, simulations are performed on grid maps, and the fusion algorithm is applied to the actual mobile robot path planning based on the ROS. Simulation and experimental results show that the fusion algorithm achieves optimization of path safety and length, enabling the robot to reach the end point safely with real-time dynamic obstacle avoidance capability.

  • Regular PapersApril 1, 2024

    Group-aggregation of Hierarchical Containment Control for Homogeneous Multi-agent Systems in Precision Agriculture

    Jingshu Sang, Dazhong Ma*, Xiangpeng Xie, and Xuguang Hu

    International Journal of Control, Automation, and Systems 2024; 22(4): 1400-1408

    https://doi.org/10.1007/s12555-022-1071-y

    Abstract

    Abstract : The mixed planting, as one of the diversification strategies, provides the substitute for many costly inputs, such as fertilizers, pesticides, imported pollinators and irrigation. However, the lack of the farming technology and the expansion of the farming scale have resulted in extremely mismatch between desired yield and manpower. This paper considers groups of agents orderly moving into precise regions, which is suitable for simultaneously planting of different crops. The hierarchical containment control strategy with group-aggregation behavior is proposed under the transformed three-layer topology. Particularly, the dynamic hierarchical containment control protocol is designed such that a novel group-aggregation cooperation in the convex hull can be achieved. A new coupling strength coefficient based on the transformed three-layer topology is defined in the proposed control protocol. Finally, two examples are provided to demonstrate the effectiveness of the proposed dynamic hierarchical containment control protocol for agricultural settings.

  • Regular PapersApril 1, 2024

    Iterative Algorithm for Feedback Nonlinear Systems by Using the Maximum Likelihood Principle

    Huafeng Xia

    International Journal of Control, Automation, and Systems 2024; 22(4): 1409-1417

    https://doi.org/10.1007/s12555-022-1002-y

    Abstract

    Abstract : This paper aims to find a maximum likelihood least squares-based iterative algorithm to solve the identification issues of closed-loop input nonlinear equation-error systems. By adopting the key term separation technique, the parameters of the forward channel are identified separately from the parameters of the feedback channel to address the cross-product terms. The hierarchical identification principle is introduced to decompose the original system into two subsystems for reduced computational complexity. The iterative estimation theory and the maximum likelihood principle are applied to design a new least-squares algorithm with high estimation accuracy by taking full use of all the measured input-output data at each iterative computation. Compared with the recursive least-squares (RELS) method. The simulation results verify theoretical findings, and the proposed algorithm can generate more accurate parameter estimates than the RELS algorithm.

  • Regular PapersApril 1, 2024

    Fault-tolerant Trajectory Tracking Control Based on DDPG Algorithm for Underwater Vehicle With Propeller Faults

    Jiao Qin, Maiying Zhong*, Wendong Gai, and Zhongjun Ding

    International Journal of Control, Automation, and Systems 2024; 22(4): 1418-1429

    https://doi.org/10.1007/s12555-022-1017-4

    Abstract

    Abstract : Due to the complexity of the underwater vehicle itself and its operating environment, it is difficult for fault detection and diagnosis (FDD) unit to obtain accurate fault information in time, which brings difficulties to the implementation of subsequent fault-tolerant control (FTC). Aiming at this question, a novel FTC method is proposed in this paper, which does not rely on FDD units and does not require any prior knowledge of faults. Firstly, a nonlinear continuous time system will be established to describe the underwater vehicle system dynamics with external disturbance, model uncertainties, propeller saturation and unknown propeller faults. To be specific, the nominal controller and fault-tolerant controller are designed respectively. When there is no fault, a nominal controller is used to realize the trajectory tracking control of the underwater vehicle and a quadratic performance index is used to describe and monitor the system performance. Based on the approximation ability of neural networks, a deep deterministic policy gradient (DDPG) algorithm is used to generate the controller compensation signal when the tracking performance degradation caused by propeller fault exceeds the pre-set threshold, so as to realize FTC. Finally, the effectiveness and feasibility of our proposed scheme are verified by simulation.

  • Regular PapersApril 1, 2024

    H∞ Exponential Synchronization of Switched Cellular Neural Networks Based on Disturbance Observer-based Control

    Linlin Hou*, Pengfei Ma, Xuan Ma, and Haibin Sun

    International Journal of Control, Automation, and Systems 2024; 22(4): 1430-1441

    https://doi.org/10.1007/s12555-022-0917-7

    Abstract

    Abstract : The problem of H∞ exponential synchronization for switched cellular neural networks that are subjected to multiple exogenous disturbances is investigated. The exogenous disturbances are rejected and attenuated by combining disturbance observer-based control with H∞ control. Based on the admissible edge-dependent average dwell time scheme and the Lyapunov-Krasovskii functional technique, a synchronization criterion formulated by linear matrix inequalities is procured for switched cellular neural networks with external disturbances. Finally, the effectiveness of the obtained results is verified through a numerical simulation.

  • Regular PapersApril 1, 2024

    Suboptimal Relational Tree Configuration and Robust Control Based on the Leader-follower Model for Self-organizing Systems Without GPS Support

    Zhi-gang Xiong, Ya-Song Luo*, Zhong Liu, and Zhi-kun Liu

    International Journal of Control, Automation, and Systems 2024; 22(4): 1442-1454

    https://doi.org/10.1007/s12555-022-0505-x

    Abstract

    Abstract : This paper surveys the formation acquisition and maintenance of multi-agent systems, while the communication graph is obtained without human designations. Given that all agents move along unpredictable paths during formation acquisition, the systems adopt the leader-follower model. For better expression of the graph construction, a relational tree is introduced to describe the follower-leader pairs. Then, a distributed method is proposed for suboptimal relational tree configuration. By utilizing particle swarm optimization (PSO), the search for follower-leader pairs is converted to permutation optimization. Based on principal component analysis (PCA), the entire group is divided into several small groups, and the optimization can be implemented in each group, thus releasing the computation burden. To acquire the formation defined by the suboptimal relational tree, a second nonlinear controller subject to the loss of GPS information is established. The controller takes the reference in the local velocity frame as inputs, and proportional and differential components are introduced to provide a soft control. In addition, adaptive parameters are designed for robust control. By tuning the parameters autonomously, self-organized systems can work well in various scenarios even without manual adjustment of parameters. Mathematical and numerical analyses are conducted to prove the feasibility of the proposed strategy.

  • Technical Notes and CorrespondenceApril 1, 2024

    Integral-event-triggered H∞ Blood Glucose Control of Type 1 Diabetes via Artificial Pancreas

    Shen Yan and Yue Cai*

    International Journal of Control, Automation, and Systems 2024; 22(4): 1455-1460

    https://doi.org/10.1007/s12555-022-0561-2

    Abstract

    Abstract : This technical note is concerned with the event-triggered H∞ blood glucose regulation issue of type 1 diabetes by using networked artificial pancreas (AP). In order to improve the service life of AP, an integral-eventtriggered scheme (IETS) is presented to reduce the releasing rate of control signal and the updating times of insulin pump. Compared with the normal event-triggered scheme (ETS), the proposed scheme can generate a larger interevent time by utilizing the integration of the triggering condition in normal ETS. To maintain the blood glucose concentration (BGC) within standard range, the co-design conditions of triggering parameter and H∞ controller are derived by linear matrix inequalities (LMIs). Finally, the validity of the developed strategy is verified through some simulation results.

IJCAS
April 2024

Vol. 22, No. 4, pp. 1105~1460

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