Leader-follower Mode Research Articles

Research on A Global Path-Planning Algorithm for Unmanned Arial Vehicle Swarm in Three-Dimensional Space Based on Theta*–Artificial Potential Field Method

The current challenge in drone swarm technology is three-dimensional path planning and adaptive formation changes. The traditional A* algorithm has limitations, such as low efficiency, difficulty in handling obstacles, and numerous turning points, which make it unsuitable for complex three-dimensional environments. Additionally, the robustness of drone formations under the leader–follower mode is low, and effectively handling obstacles within the environment is challenging. To address these issues, this study proposes a virtual leader mode for drone formation flight and introduces a new Theta*–APF method for three-dimensional space drone swarm path planning. This algorithm optimizes the A* algorithm by transforming it into an omnidirectional forward Theta* algorithm. It also enhances the heuristic function by incorporating artificial potential field methods in a three-dimensional environment. Formation organization and control of UAVs is achieved using speed-control modes. Compared to the conventional A* algorithm, the Theta*–APF algorithm reduces the search time by about 60% and the trip length by 10%, in addition to the safer flight of the UAV formation, which is subject to artificial potential field repulsion by about 42%.

Integrated the Artificial Potential Field with the Leader–Follower Approach for Unmanned Aerial Vehicles Cooperative Obstacle Avoidance

For the formation and obstacle avoidance challenges of UAVs (unmanned aerial vehicles) in complex scenarios, this paper proposes an improved collaborative strategy based on APF (artificial potential field). This strategy combines graph theory, the Leader–Follower method, and APF. Firstly, we used graph theory to design formation topology and dynamically adjust the distances between UAVs in real time. Secondly, we introduced APF to avoid obstacles in complicated environments. This algorithm innovatively integrates the Leader–Follower formation method. The design of this attractive field is replaced by the leader’s attraction to the followers, overcoming the problem of unreachable targets in APF. Meanwhile, the introduced Leader–Follower mode reduces information exchange within the swarm, realizing a more efficient “few controlling many” paradigm. Afterwards, we incorporated rotational force to assist the swarm in breaking free from local minima. Ultimately, the stability of the integrated formation strategy was demonstrated using Lyapunov functions. The feasibility and effectiveness of the proposed strategy were validated across multiple platforms.

Collaborative pursuit-evasion game of multi-UAVs based on Apollonius circle in the environment with obstacle

In the game of a two-dimensional plane with a circular obstacle, a strategy of multi-pursuers and a single evader is studied. All the agents are Unmanned Aerial Vehicle and the evader is faster than the pursuers. The collaborative pursuit-evasion mission is divided into two stages: the encirclement stage and pursuit-evasion stage. When pursuers fly to the mission area from a distance, the formation and obstacle avoidance method based on leader-follower mode is designed for the encirclement process. In the pursuit-evasion stage, considering obstacle avoidance and manoeuver constraint, a collaborative strategy combining Apollonius circle algorithm and geometric algorithm is proposed, and the condition for the successful capture of a single superior evader is analysed. In the simulation, the influence of obstacle size and manoeuver constraint is compared and analysed in detail, which indicates that they will increase the capture time even changes the result of the game in the limited map. In addition, the complexity of the algorithm is M times higher than that of the obstacle-free case ( M is the number of obstacles in the map).

Research on a Control Strategy for a Distributed Economic Dispatch System in an Active Distribution Network, Considering Communication Packet Loss

The benefits of a distributed economic dispatch system include significant resilience, uniform processing and communication pressure, and good scalability, but, currently, there is limited in-depth research on the impact of packet loss on the communication links of a distributed economic dispatch system. To analyze how communication packet loss affects a distributed economic dispatch system and to develop appropriate scheduling approaches, in this paper, we design a fully distributed economic dispatch strategy for an active distribution network (ADN) in leader-follower mode, we use the Bernoulli stochastic process to describe the communication packet loss phenomenon, and we give sufficient conditions for the system in the form of linear matrix inequality (LMI) to be able to achieve stochastic stability. The communication packet loss probability affects the convergence performance of the system, and a high packet loss probability can cause the system to lose stability. By simulating various situations in the IEEE-14 and IEEE-39 systems, in this study, we confirm the validity and efficacy of the distributed economic dispatch control strategy and the system stability analysis method.

Compact Midwave Imaging System: Results from an Airborne Demonstration

The Compact Midwave Imaging System (CMIS) is a wide field of view, multi-angle, multi-spectral pushframe imager that relies on the forward motion of the satellite to create a two-dimensional (2D) image swath. An airborne demonstration of CMIS was successfully completed in January–February 2021 on the NASA Langley Research Center Gulfstream III. The primary objective of the four-flight campaign was to demonstrate the capability of this unique instrument to perform stereo observations of clouds and other particulates (e.g., smoke) in the atmosphere. It is shown that the midwave infrared (MWIR) spectral bands of CMIS provide a unique 24/7 capability with high resolution for accurate stereo sensing. The instrument relies on new focal plane array (FPA) technology, which provides excellent sensitivity at much warmer detector temperatures than traditional technologies. This capability enabled a compact, low-cost design that can provide atmospheric motion vectors and cloud heights to support requirements for atmospheric winds in the 2017–2027 Earth Science Decadal Survey. Applications include day/night observations of the planetary boundary layer, severe weather, and wildfires. A comparison with current space-based earth science instruments demonstrates that the SWIR/MWIR multi-spectral capability of CMIS is competitive with larger, more expensive instrumentation. Imagery obtained over a controlled burn and operating nuclear power plant demonstrated the sensitivity of the instrument to temperature variations. The system relies on a mature stereoscopic imaging technique applied to the same scene from two independent platforms to unambiguously retrieve atmospheric motion vectors (AMVs) with accurate height assignment. This capability has been successfully applied to geostationary and low-earth orbit satellites to achieve excellent accuracy. When applied to a ground-point validation case, the accuracy for the CMIS aircraft observations was 20 m and 0.3 m/s for cloud heights and motion vectors, respectively. This result was confirmed by a detailed error analysis with analytical and covariance models. The results for CMIS cases with underflights of Aeolus, CALIPSO, and Aqua provided a good validation of expected accuracies. The paper also showed the feasibility of accommodating CMIS on CubeSats to enable multiple instruments to be flown in a leader–follower mode.

Design, Development, and Testing of an Intelligent Wearable Robotic Exoskeleton Prototype for Upper Limb Rehabilitation.

Neuromotor rehabilitation and recovery of upper limb functions are essential to improve the life quality of patients who have suffered injuries or have pathological sequels, where it is desirable to enhance the development of activities of daily living (ADLs). Modern approaches such as robotic-assisted rehabilitation provide decisive factors for effective motor recovery, such as objective assessment of the progress of the patient and the potential for the implementation of personalized training plans. This paper focuses on the design, development, and preliminary testing of a wearable robotic exoskeleton prototype with autonomous Artificial Intelligence-based control, processing, and safety algorithms that are fully embedded in the device. The proposed exoskeleton is a 1-DoF system that allows flexion-extension at the elbow joint, where the chosen materials render it compact. Different operation modes are supported by a hierarchical control strategy, allowing operation in autonomous mode, remote control mode, or in a leader-follower mode. Laboratory tests validate the proper operation of the integrated technologies, highlighting a low latency and reasonable accuracy. The experimental result shows that the device can be suitable for use in providing support for diagnostic and rehabilitation processes of neuromotor functions, although optimizations and rigorous clinical validation are required beforehand.

Smartphone-Based Indoor Visual Navigation with Leader-Follower Mode

Existing indoor navigation solutions usually require pre-deployed comprehensive location services with precise indoor maps and, more importantly, all rely on dedicatedly installed or existing infrastructure. In this article, we present Pair-Navi, an infrastructure-free indoor navigation system that circumvents all these requirements by reusing a previous traveler’s (i.e., leader) trace experience to navigate future users (i.e., followers) in a Peer-to-Peer mode. Our system leverages the advances of visual simultaneous localization and mapping ( SLAM ) on commercial smartphones. Visual SLAM systems, however, are vulnerable to environmental dynamics in the precision and robustness and involve intensive computation that prohibits real-time applications. To combat environmental changes, we propose to cull non-rigid contexts and keep only the static and rigid contents in use. To enable real-time navigation on mobiles, we decouple and reorganize the highly coupled SLAM modules for leaders and followers. We implement Pair-Navi on commodity smartphones and validate its performance in three diverse buildings and two standard datasets (TUM and KITTI). Our results show that Pair-Navi achieves an immediate navigation success rate of 98.6%, which maintains as 83.4% even after 2 weeks since the leaders’ traces were collected, outperforming the state-of-the-art solutions by >50%. Being truly infrastructure-free, Pair-Navi sheds lights on practical indoor navigations for mobile users.

A Cournot game model for integrated energy service transaction in electric-gas coupled market

Based on the analysis of the game behaviours of multi-energy players, for the purpose of maximining the utility of market entities, this study establishes a Cournot game model in the electricity-gas coupled market for multi-energy players, which include the pricing model of multi-energy players in Leader-Follower mode and the operation optimization model between multi-energy players and local energy system based on Stackelberg game. Through the example analysis, it is demonstrated that the master-slave model has good convergence properties and plays a vital role in the interaction process between different decision-making bodies and find the optimal strategy, which can provide important reference information for the decision-makers and has certain practical value.

CoUAS

In the past decade, unmanned aircraft systems (UASs) have been widely used in various civilian applications, most of which involve only a single unmanned aerial vehicle (UAV). In the near future, more and more UAS applications will be facilitated by the cooperation of multiple UAVs. In such applications, it is desirable to utilize a general control platform for cooperative UAVs. However, existing open-source control platforms cannot fulfill such a demand because (1) they only support the leader-follower mode, which limits the design options for fleet control, (2) existing platforms can support only certain type of UAVs and thus lack compatibility, and (3) these platforms cannot accurately simulate a flight mission, which may cause a big gap between simulation and real-world flight. To address these issues, we propose a general control and monitoring platform for cooperative UAS, namely, CoUAS , which provides a set of core cooperation services of UAVs, including synchronization, connectivity management, path planning, energy simulation, and so on. To verify the applicability of CoUAS, we design and develop a prototype in which an embedded path planning service is provided to complete any task with the minimum flying time while considering the network connectivity and coverage. Experimental results by both simulation and field test demonstrate that the proposed system is viable.

Leader-following flocking for unmanned aerial vehicle swarm with distributed topology control

To address the flocking issues of an unmanned aerial vehicle (UAV) swarm operating at a leader-follower mode, distributed control protocols comprising both kinetic controller and topology control algorithm must be implemented. For flocking the UAV swarm, a distributed control-input method is required forboth maintaining a relatively steady state between neighboring vehicles (including velocity matching and distance maintenance) and avoiding vehicle-to-vehicle collision. Furthermore, the stability of control protocols should be analyzed using the potential energy function. In particular, a distributed $\beta~$-angle test (BAT) rule in the proposed topology-control issue may allow each UAV to determine its neighboring set by exploiting the locally sensed information, thereby significantly reducing the communication overhead of the entire swarm. In addition, node-degree bound is derived to demonstrate the feasibility of the proposed algorithm, in which the optimal value in terms of convergence is analyzed. The flocking of the flying ad-hoc network (FANET) can be achieved in a self-organizing way without the use of an external control center via the distributed control protocols. Ultimately, the proposed analysis is verified by numerical results.

Formation control for underactuated unmanned surface vehicles based on consistency theory and leader-follower mode

The formation involving multiple unmanned surface vehicles (USVs) is a new hotspot in research on USVs. Considering the formation control problem of underactuated USVs, a distributed formation control algorithm is proposed based on consistency theory and leader-follower mode. The motion processes of the reference USV with respect to each USV are obtained with a consistency algorithm. By adjusting the control input, each USV converges to the reference vehicle. Thus, the expected formation of all USVs can be guaranteed if the trajectories of these two types of USVs coincide. The entire formation uses distributed control, which has certain tolerance to special situations, such as communication delay and communication interruption. The effectiveness of the control strategy is verified through simulations.

Formation control for underactuated unmanned surface vehicles based on consistency theory and leader-follower mode

Formation control for underactuated unmanned surface vehicles based on consistency theory and leader-follower mode

Valuable strategy and firm performance in the O2O competition

When the manufacturer opens an online channel to compete with its traditional retailer, what valuable strategy can be utilized to alleviate the O2O (online to offline) competition and conflict and improve the performances of all channel members? Our research addresses this important question by initiating an innovative strategy considering the retailer's sales effort and the manufacturer's support in local advertising simultaneously in a manufacturer – retailer O2O supply chain. Our results show that although the retailer's sales effort helps improve the channel coordination and leads to a win-win solution for both the manufacturer and the retailer, investing in both the retailer's sales effort and manufacturer's support in local advertising is a more effective strategy to be employed to coordinate the O2O distribution and achieve higher profits for all parties in the manufacturer - retailer supply chain. In addition, our results also show that compared to the simultaneous mode, the Stackelberg leader-follower mode provides no competitive advantage to the manufacturer or the retailer when the retailer's sales effort and manufacturer's support in local advertising strategy is implemented to coordinate the O2O distributions.

The caging configuration design and optimization for planar moving objects using multi-fingered mechanism

ABSTRACTDue to the larger number of fingers, and the relative motion between object and fingers, the moving object caging using multi-fingered mechanism is complicated and difficulty. In this paper, a novel algorithm for planar moving objects caging configuration design and optimization using multi-fingered mechanism is proposed. In the proposed algorithm: (1) the lead finger is chosen and controlled to track the caging point nearby the moving object; (2) possible configurations of following fingers are determined according to interconnections of the multi-fingered mechanism; (3) the caging condition is applied to choose effective caging configurations. Compared to existing methods, advantages of the proposed method lie on the simple task mode – ‘leader-follower mode’ and low calculation burden. In addition, considering caging is a loose closure strategy with a certain margin, the caging margin, which is the space between the multi-fingered mechanism and the moving target, is introduced and quantified. Moreover, the caging configurations are optimized to maximize the caging margin to provide maximum local freedom for the object. For verifying the efficiency of the proposed method, it is applied in the rectangular and regular pentagonal shaped moving objects caging problems, and the simulation results illustrate the validity of the proposed algorithm.

A leader–follower formation control approach for target hunting by multiple autonomous underwater vehicle in three-dimensional underwater environments

As one of the challenging tasks of multiple autonomous underwater vehicles systems, the realization of target hunting is the great significance. The multiple autonomous underwater vehicle target hunting is studied in this article. In some research, because the hunting members cannot reach the hunting point at the same time, the hunting time is long or the target escapes. To improve the efficiency of the target hunting, the leader–follower formation algorithm is introduced. Firstly, the task is assigned based on the distance between the autonomous underwater vehicle and the target. Then, the autonomous underwater vehicles with the same task are formed based on leader–follower mode, and the formation is kept to track the target. In the final capture phase, multiple autonomous underwater vehicle system use angle matching algorithm to round up target. The simulation results show that the proposed algorithm can effectively accomplish the target hunting task, save the hunting time, and avoid the target escape. Compared with the bioinspired neural network algorithm, the proposed algorithm shows better performance.

Highly Available Dynamic Deployment Algorithm Based on Leader-Follower Mode in SDN

Controller is the core of the Software Defined Network (SDN) network architecture, how to ensure the stability of the network operation process by dynamically deploying controllers is one of the important tasks of the SDN network. This paper proposes a highly available dynamic deployment algorithm based on the leader-follower mode. First, leader and follower controllers are determined through a neighborhood leader controller election algorithm based on Paxos protocol; secondly, the leader controller performs a time optimal allocation algorithm based on load constraint to determine the distribution plan of the switches under the failed controller; finally, the slave controllers perform the switch migration operation according to the distribution result to complete network failure recovery. The simulation results show that the proposed algorithm ensures the controller not overloaded during the fault recovery, and has a lower controller average response delay than other similar algorithms.

Formation tracking control for multi-agent systems: A wave-equation based approach

This paper considers the formation tracking control problem of large-scaled Multi-Agent Systems (MAS) for which the model is based on a system of mutually independent wave Partial Differential Equations (PDEs). The spatial derivatives in the equation correspond to the underlying communication topology of the agents. A leader-follower mode is employed in the control algorithm, with which the agents on the boundary of PDEs are chosen as leaders knowing the tracking trajectory and all the other agents are followers. Each follower has only the information of its own relative position and velocity to its topological neighbors. With a designed distributed controller, the formation tracking error is bounded by a constant proportional to the acceleration of the desired trajectory. Robustness of the control law to a perturbation in the velocity measurement is also discussed. Furthermore, some simulation studies are provided to show the effectiveness of the control algorithm.

Research on three - dimensional Cooperative Formation of Sea and Air for Cruise and Rescue

Aiming at the problems of maritime traffic safety, a new model of jointing USV and UAV for Three-dimensional cruise and rescue is studied. Using the Information Fusion Technology, through the leader-follower formation mode, The collaborative fleet remote control. At the same time, it discusses how to carry out effective supervision on the responsible sea area under the complicated and changing sea conditions, especially the quick and efficient completion of the maritime search and rescue mission.

Adaptive repetitive learning control for trajectory-keeping of satellite formation flying

An adaptive repetitive control scheme is proposed for trajectory-keeping of satellite formation flying in the leader–follower mode which is described by Lawden equation. The system is parameterised by power series approximation and the unknown time-varying parameters are estimated by adaptive repetitive learning law. Through rigorous analysis by constructing a Lyapunov-like composite energy function (CEF), the stability of the closed-loop system is proved. Finally, a simulation example is provided to illustrate the effectiveness of the control algorithms proposed in this paper.

Elastic Formation Keeping Control of Unmanned Aerial Vehicle Adapting to Flight Speed

For an Unmanned Aerial Vehicle (UAV) formation in leader-follower mode, considering the relative position relationship between neighbor vehicles in the formation, an elastic distance vector is proposed. The dynamic equations of a flight speed adaptive UAV formation are established using the elastic distance vector we proposed. The state feedback controller is designed. Simulation results show that the controller can be used to control the follower vehicles to follow the leader vehicle maneuvering effectively and keep the desired formation well, most importantly, the relative distance between neighbor vehicles in the formation is adapted to the changes of flight speed.