Formation Control Of Systems Research Articles

Cerebellar Model Articulation Neural Network-Based Distributed Fault Tolerant Tracking Control with Obstacle Avoidance for Fixed-Wing UAVs

In this paper, the distributed fault-tolerant tracking control (FTTC) and obstacle avoidance problem is investigated for multiple unmanned aerial vehicles (UAVs) considering lumped disturbances and communication link faults. Firstly, a cerebellar model articulation neural network (CMANN) is introduced to esti-mate the lumped disturbances. Meanwhile, the distributed virtual leader state observers are used to address unknown communication faults. Then, a distributed nonsingular fast terminal sliding mode formation controller is implemented to track desired trajectory, and an virtual-agent artificial potential function (VAAPF) is designed to accomplish obstacle avoidance. Furthermore, the stability of the closed loop formation control systems with obstacle avoidance is proved using graph theory and Lyapunov theory. Finally, simulation results of three fixed-wing UAVs are given to show the effectiveness and good performance of the proposed scheme.

Adaptive prescribed time control for quadrotor formation with stochastic links failure

AbstractThe formation control for multiple quadrotors subject to maintaining the formation configuration and collision avoidance in the situation of stochastic links failure is investigated in this paper. First, the distributed formation controller is designed, the position controller is developed to manage the desired formation of position, and the attitude controller is developed to control the translation and rotation movements of the quadrotor. Then, in order to avoid the collisions between multiple quadrotors and the obstacles, a potential energy function method is introduced into the quadrotor formation control combined with the nest adaptive control. Inspired by the design of event trigger controller, a communication compensation controller is designed to ensure the stability of quadrotor formation under the condition of random communication interruption and recovery. Moreover, a prescribed time function is designed, which means the convergence time of the formation system can be set in advance. The prescribed time stability of the formation control system is proved by Lyapunov theory. Finally, the simulation results verify the effectiveness and superiority of this method.

Fuzzy adaptive observer–based resilient formation control for heterogeneous multiple unmanned aerial vehicles with false data injection attacks and prescribed performance

This paper addresses the resilient formation control problem for heterogeneous multiple unmanned aerial vehicles (multi-UAV) under false data injection (FDI) attacks and prescribed performance constraints. The case of both actuator and sensor attacks is considered simultaneously, and the multi-UAV can exchange the information through a directed communication network. A fuzzy adaptive observer (FAO) is first proposed to estimate the FDI attacks and the unmeasurable velocity information for each UAV. In order to transform the formation control of heterogeneous multi-UAV into a trajectory tracking control problem of individual UAVs, a bank of distributed estimators is designed to achieve the leader’s states by only using local information among neighboring UAVs. Then, by incorporating a novel tracking error transform method and fractional-order sliding mode control technique, a resilient prescribed performance tracking controller without velocity measurements is constructed. Furthermore, it is proved that all signals of the closed-loop formation control systems are uniformly ultimately bounded (UUB) stable under FDI attacks. Finally, the simulation results are given to verify the effectiveness and superiority of the proposed control strategy.

Real-time crowd formation control in virtual scenes

This paper presents a formation control system that can be applied in many areas under defined conditions. The system allows users to simplify interaction and quickly complete formation arrangements in virtual scenarios. At the same time, the system allows the user to input specific formations to meet requirements, such as war formations in video games or formation arrangements for stage performances. It also recognizes user input through a human–computer interaction method based on gesture recognition and finds the best corresponding formation from a library of predefined and user-defined formations. The system ensures real-time user interaction and control by automatically scaling the group size and controlling the group movement according to the unit density. During formation changes, the minimum energy principle is applied to determine the ideal position of each agent in the target formation to increase the efficiency of its movement. In addition, formation stability is maintained during collision avoidance by combining potential obstacle fields with a rigid formation network. Finally, the proposed formation system is tested qualitatively and compared quantitatively with the execution efficiency of some existing interactive formation methods. The experimental results show that the method can effectively implement formation control in a virtual scene. It can automatically avoid obstacles and maintain the formation during the formation morphing process.

A Vision-Based Underwater Formation Control System Design and Implementation on Small Underwater Spherical Robots

The ocean is a significant strategic resource, and the insufficient development and use of the ocean, as well as the increase in attention to the ocean, have led to the development of underwater robot technology. The need for in-depth marine exploration and the limitations of one underwater robot has sparked research on the underwater multi-robot system. In the underwater environment, weak communication is caused by the shielding effect of the seawater medium, which makes multi-robot systems difficult to form. Hence, we combine the robot’s vision system with the leader-follower structure to form a vision-based underwater formation method, in which the visual solution serves as the control system’s feedback. By using three small underwater robot platforms, the proposed method is proved to be effective and practicable through underwater formation experiments. Furthermore, the coordination period and error of the control system are analyzed.

Finite time fault tolerant tracking control for multiple unmanned aerial vehicles with actuator faults

SummaryAn adaptive fast nonsingular integral terminal sliding mode control scheme is proposed for the distributed formation control problem of multiple unmanned aerial vehicles (UAVs) affected by actuator faults and external disturbances. In order to achieve a good cooperative tracking performance of UAVs during mission execution, the adverse effect of the lumped disturbances composed of actuator failures, wind and vortex disturbances is estimated by the cerebellar model articulation neural network, meanwhile the tangent function is introduced to eliminate the chattering of the sliding mode. Then the analysis of superior convergence performance of the fast nonsingular integral terminal sliding manifold is implemented, and the finite time stability of the closed‐loop formation flight control system is proved. Finally, the simulation experiments verify that the proposed approach is superior to the nonsingular integral terminal sliding mode control for the formation control system of faulty multiple UAVs.

Adaptive neural sliding mode control for heterogeneous ship formation keeping considering uncertain dynamics and disturbances

This paper investigates the formation keeping problem of heterogeneous ships with underactuated inputs, uncertain dynamics, and environmental disturbances. The control objective is to make the heterogeneous followers keep the desired formation while tracking a leader. To solve the problem effectively, a novel virtual leader–follower formation scheme considering the ship heterogeneity is proposed by utilizing the backstepping method, adaptive neural network, and adaptive control law. The stability of the formation control system is proved based on Lyapunov’s direct method where all tracking errors are guaranteed to be uniformly ultimately bounded. Finally, simulations and comparisons are conducted to verify the effectiveness of the proposed control law.

Terminal sliding-mode disturbance observer-based finite-time adaptive-neural formation control of autonomous surface vessels under output constraints

AbstractThis paper proposes a tracking controller for the formation construction of multiple autonomous surface vessels (ASVs) in the presence of model uncertainties and external disturbances with output constraints. To design a formation control system, the leader-following strategy is adopted for each ASV. A symmetric barrier Lyapunov function (BLF), which advances to infinity when its arguments reach a finite limit, is applied to prevent the state variables from violating constraints. An adaptive-neural technique is employed to compensate uncertain parameters and unmodeled dynamics. To overcome the explosion of differentiation term problem, a first-order filter is proposed to realize the derivative of virtual variables in the dynamic surface control (DSC). To estimate the leader velocity in finite time, a high-gain observer is effectively employed. This approach is adopted to reveal all signals of the closed-loop system which are bounded, and the formation tracking errors are semi-globally finite-time uniformly bounded. The computer simulation results demonstrate the efficacy of this newly proposed formation controller for the autonomous surface vessels.

Fixed-Time Formation Control for Unmanned Surface Vehicles with Parametric Uncertainties and Complex Disturbance

In this paper, under parametric uncertainties and complex disturbances, a leader–follower formation control strategy based on accurate disturbance observer (ADO) and a novel fixed-time fast terminal sliding mode (FTFTSM) control for unmanned surface vehicles (USVs) is proposed. The main contributions of this paper are: (1) A novel fixed-time fast terminal sliding mode tracking control (FTFTSM-TC) strategy is designed for the tracking control subsystem, which greatly improves the convergence rate of the leader USV in trajectory tracking. (2) An ADO is designed to observe lumped disturbances with the smallest approximation error. The ADO greatly reduces the interference of disturbances and improves the performance of the formation system. (3) An ADO-based fixed-time formation control (ADO-FTFC) strategy is developed for the formation control subsystem to maintain the desired formation. Stability of the formation control system is established by the Lyapunov theory. Simulation results show that the proposed control strategy is superior for the USVs formation control.

Distributed predictive formation control for autonomous underwater vehicles under dynamic switching topology

Numerous existing autonomous underwater vehicles (AUVs) formation control works have focused on the preconfigured communication topology. However, the complex marine environment reveals the limitations and unreliability of the fix topology scheme. In this paper, the formation control of AUVs is investigated under dynamic switching topology. In order to realize this objective, the 2-D Delaunay triangulation and Jaccard index are introduced. A formation control system based on intermittent broadcast, rather than the traditional distributed control system, is established based on a leader-follower strategy. During the process of formation moving, the input constraints, vehicle collision avoidance and input saturation needed to be noted. To this end, the model predictive control algorithm is employed to design the formation controller, and the stability of the formation control system is proved by the average residence time notion and Lyapunov stability. The numerical simulations are exhibited to illustrate the effectiveness of the proposed formation control schemes in connectivity preservation and formation generation.

Formation tracking control for underactuated surface vehicles with actuator magnitude and rate saturations

In this paper, a formation tracking problem with collision avoidance is investigated for underactuated surface vehicles (USVs) with actuator magnitude and rate saturations. The USVs are subject to model uncertainties and external disturbances. A nonlinear extended state observer (NESO) is used to recover the linear velocity and yaw rate as well as unknown uncertainties and disturbances. A distributed control law is designed by artificial potential functions (APFs), the NESO and a backstepping technique. The APFs combined with a strategy are employed to achieve collision avoidance. Additional controllers are employed to deal with the underactuated problem, actuator magnitude and rate saturations. The stability of formation control system and simulation results are performed to illustrate the effectiveness of the proposed strategy.

Discrete-time formation control of multiple heterogeneous underwater gliders

The formation control of underwater gliders has been widely concerned due to its practical potential in various applications of ocean observation. This paper investigates the problems of formation control of multiple heterogeneous gliders based on consensus algorithm with discrete information. A nonlinear second-order dynamic model is obtained for the complex nonlinear underactuated gliders. By combining the consensus of speed control in forward direction and path following in lateral direction, formation control protocol with unavailable velocity information and asynchronous communication is proposed for multiple gliders. The glider formation control system (GFCS) is designed to drive a fleet of gliders following a set of explicitly specified trajectories. Two cases of simulation with six heterogeneous gliders and six homogeneous gliders respectively are performed to demonstrate the methodology and verify the effectiveness and reliability of the formation control protocol for discrete-time multi-glider system, which is proved to be applicable to formation scaling and transformation of multiple gliders.

A Leader-Follower Trajectory Tracking Controller for Multi-Quadrotor Formation Flight

The aim of this work is to design a control system based on modern control methods to control flight formations of quadrotor unmanned aerial vehicles. A leader-follower methodology is implemented where the leader vehicle has some predefined trajectory, and the follower vehicles are controlled in order to track the leader while keeping a constant displacement. The formation control system, responsible for the vehicle formation, considers, at first, only the motion at a constant height, and secondly, the three-dimensional motion. In both cases, the nonlinear control laws are derived based on Lyapunov stability theory and the Backstepping method. The control laws are validated in simulation, resorting to a realistic environment and vehicle models.

Distributed bearing‐based formation control and network localization with exogenous disturbances

AbstractIn this article, we present a generalized robust stability analysis for distributed bearing‐based formation control and network localization systems in a global reference frame. Different from many existing studies under ideal circumstances, we analyze stability of bearing‐based systems with general time‐varying exogenous disturbances. In addition to analyzing stability, explicit upper‐boundary sets of bearing formation control and network localization errors are derived via Lyapunov stability analysis. By computing the upper‐boundary sets of errors, we could obtain beneficial information for reducing and estimating the bounded errors. Since various sources of disturbances exist in reality, the research on robustness issues in this direction has potential benefits for practical applications to deal with system errors.

Velocity-Free Formation Control and Collision Avoidance for UUVs via RBF: A High-Gain Approach

This paper designs an adaptive formation control system for unmanned underwater vehicles (UUVs) in the presence of unmeasurable states and environmental disturbance. To solve the problem of unmeasurable UUV states, a filtered high-gain observer (FHGO) is employed to estimate the states, despite measurement noise. Then, an adaptive control scheme is designed to achieve UUV formation collision avoidance. The radial basis function (RBF) is used to estimate the unknown disturbance. The stability of UUV formation with collision avoidance is proven by using the Lyapunov theorem. Numerical simulation is carried out to demonstrate that the proposed filtered high-gain observer is successful in estimating the states of UUVs. The control law can keep the UUV formation from collision with good performance.

Event-based rigid formation system with cooperative finite-time control

Abstract We note that most of the rigid formation control based on distance-constrained theory only guarantees exponential or asymptotic convergence of the system. In this paper, we proposed a finite-time event-based control scheme applied in rigid formation control system. Centralized finite-time event-based formation control system is designed where the next trigger time is determined by a central event-based controller, which broadcasts and updates the control input signal to all agents. Then, we build a distributed finite-time event-based control strategy, different from the above system where each agent only uses its own local information. For the above two protocols, we discussed the trigger situation, which ensures that the formation system converges in a finite time. Finally, simulation results proved the performance and effectiveness of the proposed finite-time event-based scheme.

Fault-tolerant control system for the formation of carbon products

The production of carbon products is largely resource- and energy-intensive. That is why increasing the efficiency of this production is an urgent scientific and practical task, especially in modern conditions of constant growth of energy costs. An effective way to solve this problem is to create a modern process control system, taking into account possible failures of system components. A method for the synthesis of a fault-tolerant control system for the cyclic formation of carbon products has been developed, which takes into account control errors that are caused by malfunctions of controllers under conditions of unknown disturbances. According to the cyclic nature of the technological process under consideration, a control method with iterative learning was used in the synthesis of the control system. This method considers cyclic processes based on a two-dimensional model (2D model). The proposed control algorithm ensures the convergence of the control process with the task both in time and in each work cycle in order to promote the required quality of control even in the event of unknown disturbances and errors in the performance of controllers. The synthesis of the control system is based on the solution of a system of linear matrix inequalities. Based on the combination of a control method with iterative learning and a control method that takes into account failures in controllers, a method of constructing a fault-tolerant control system for the cyclic formation of carbon products has been synthesized to ensure acceptable operation of the control object in abnormal conditions. The control system has been synthesized by solving a system of linear matrix inequalities with the MATLAB software. In the future, it is necessary to consider optimal settings of the proposed control system and examine its effectiveness in comparison with conventional fault-tolerant systems for non-cyclic processes.

Development and Simulation of Motion Control System for Small Satellites Formation

In the paper, the problem of forming and maintaining the small satellites formation in the near-earth projected circular orbits is considered. The satellite formation reconfiguration and formation-keeping control laws are proposed by employing the passivity-based output feedback control. For the complete nonlinear and time-dependent dynamics of the relative motion of a pair of satellites in elliptical orbits, new combined control algorithms, including a consensus protocol, are proposed and analyzed. A comparison of the control modes using the passivity-based output feedback control and the proportional-differential controller with and without the consensus algorithm is given. On the basis of the passification method, the algorithm is obtained ensuring the stable motion of the slave satellite relative to the orbit of the master satellite. To improve the accuracy of the satellites’ positioning, a consensus protocol based on measurements of the relative positions of the satellites is proposed and studied. Computer simulations of the proposed algorithms for options to construct formations are provided for two projected circular orbits of 8 satellites, demonstrating the efficiency of the proposed control schemes. It is shown that the resulting passivity-based output feedback control provides better accuracy than the PD controller. It is also shown that the use of the consensus protocol further increases the positioning accuracy of the satellite constellation.

Broad-RBFNN-Based Intelligence Adaptive Antidisturbance Formation Control for a Class of Cluster Aerospace Unmanned Systems with Multiple High-Dynamic Uncertainties

This paper investigates the antidisturbance formation control problem for a class of cluster aerospace unmanned systems (CAUSs) suffering from multisource high-dynamic uncertainties. Firstly, to estimate and compensate the uncertainties existing in CAUS coordinate dynamics, an adaptive antidisturbance formation control law, which is combined by a robust adaptive control law and the second order disturbance observer, has been designed. Secondly, aiming at the adverse influences caused by the nonlinear time-varying nonlinearities existing in the formation flight dynamics, the radial basis function neural network (RBFNN) is introduced. Furthermore, considering the rapidly varying characteristics of the aforementioned formation flight nonlinearities, a novel board RBFNN (B-RBFNN) has been constructed and utilized to improve the approximation and compensation performance. In virtue of the fusing of the B-RBFNN and the second-order disturbance observer-based adaptive formation control law, the rapid response rate and the higher control accuracy of the formation control system can be achieved. As a result, a novel B-RBFNN-based intelligence adaptive antidisturbance formation control algorithm has been established for CAUS trajectory coordination and formation flight. Numerical simulation results are proposed to illustrate the effectiveness and advantages of the proposed B-RBFNN-based intelligent adaptive formation control method for the CAUS.

Formation Control of Dual Auto Guided Vehicles Based on Compensation Method in 5G Networks

With commercial application of 5G networks, many researchers have started paying attention to real-time control in 5G networks. This paper focuses on dual auto guided vehicles collaborative transport scenarios and designs a formation control system in current commercial 5G networks. Firstly, the structure of the 5G network researched in this paper is introduced. Then the round-trip time of 5G networks is measured and analyzed. The result shows that although the 5G round-trip time has randomness, it is mainly concentrated in 19 ± 3 ms, and the jitter mainly in 0 ± 3 ms. The Kalman filter is applied to estimate the transmission delay and experiment result shows the effectiveness of the estimation. Furthermore, the total delay including transmission delay and execution delay in control system is discussed. After establishing the AGV kinematic and formation model, complete control system based on compensation method is proposed. Finally, an experiment is carried out. Compared to the result without formation control, maximum distance error is reduced by 82.61% on average, while maximum angle error 45.91% on average. The result shows the effectiveness of the control system in formation maintaining in 5G network.