We present an overview of formation control for multi-agent systems. Multi-agent formation cooperation is important to accomplish assigned tasks more efficiently and safely compared to a single agent. For the way information flows between agents, we divide the available results into communication-based topologies as well as vision-based formation controls. Then, we summarize the problem formulation, discuss the differences, and review the latest results on formation control schemes. Lastly, we give research recommendations for multi-intelligent agent controls in a certain period in the future.

In this paper, an anti-disturbance control for UAVs formations in a three-dimensional environment using relative information is proposed. To accurately describe the UAV cluster motion error in a three-dimensional environment, an error estimation model based on the UAV model is established to realize the UAV state estimation based on relative information. The control law to achieve the stability of the UAV formation under bounded perturbation is also derived using the backstepping control strategy. Next, to realize that the UAV formation can achieve optimal control under performance constraints, an algorithm based on model predictive control is proposed, and an ant colony algorithm is used to accelerate the solution process. Then, the stability of the UAV formation under the action of this algorithm is investigated. Finally, the superiority and effectiveness of the algorithm compared with the traditional backstepping control method are verified through comparative simulations.

Immunopathologic aspects of bullous skin diseases were studied in paraffin sections of thirty-three skin biopsy specimens utilizing monoclonal antibodies directed against histiocytes, helper/inducer T lymphocytes, and Langerhans cells in skin lesions. Laboratory examinations revealed that either more or fewer of the standard number of helper/inducer T lymphocytes (UCHL1+) were observed in the upper dermis in 84.8% of the cases examined, particularly in the various forms of pemphigus; histiocytes (MAC387+) were also found to occur in the upper dermis in 45.5% of the cases and blisters in 27.3% of the cases, particularly in pemphigus erythematosus and dermatitis herpetifomis. In 54.5% of all the cases, both UCHL1+ and MAC387+ cell infiltrates predominated in the upper dermis. These findings suggest that a cell-mediated immune response may also be important in the pathogenesis of bullous skin diseases. It may be possible that antigen from keratinocytes can produce ETAF, and that IL1 activating T lymphocytes and histiocytes also produce IL1 activating T cells, particularly helper/inducer T cells. Such activities would further promote the increase of B cell function and immunoglobulin synthesis.

The problem of vision-based fixed-wing UAV formation control under communication limitations and the presence of measurement errors was investigated. In the first part of this paper, the single UAV motion model and the process of estimating the neighboring UAV states using the Extended Kalman Filter are introduced. The second part describes how we designed a sliding mode controller considering the sensor measurement errors and discusses the sufficient conditions for the stability and formation system in the presence of state transfer time delays in the formation. The main motivation of this paper was to develop a hierarchical, globally stable sliding mode controller that could enable the considered vision-based multiple fixed-wing UAVs to achieve and maintain formation in the presence of measurement errors. To this end, the selected problem was first transformed into a state-tracking problem for UAVs in the neighborhood, and then the stability criterion was established using the Lyapunov stability theory. Finally, the effectiveness of the proposed control method was illustrated using three numerical arithmetic examples.

In service economy era, servitization has been a worldwide trend in manufacturing. As the core action of marketing, exchange determines the motivation and hierarchical division of offering servitization. According to main factors of exchange , this paper gives a hierarchical division of the concept of servitization, and classifies different terms that describe the phenomenon in the field of marketing according to the evolution of the relationship between product and service, the process and result of servitization.