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Distributed control is the most popular control strategy for controlling numerous slave devices. However, the performance of slave devices is hard to improve because the control algorithm is handled by the commercial slave devices. Therefore, this paper proposes a hybrid control structure that follows the concept of centralized control strategy and handles part of the control loop on the master computer in a distributed control system through EtherCAT fieldbus. In this study, different advanced control methods such as robust control and learning control were applied to handle the position control loop of a scanning mirror system in a selective laser melting (SLM) system with stringent demand of position error around 40 µm based on EtherCAT fieldbus. By designing a proper controller, the experiment results showed that the tracking performance was significantly improved. The tracking error dropped by about 80% after the proposed hybrid control structure was applied. By applying the proposed hybrid control structure, one can improve the high-performance-requirement devices, while reducing the calculation burden of the master computer for other low-performance-requirement devices by retaining the benefit of distributed control. [ABSTRACT FROM AUTHOR]

In this paper, a cascade control structure with the modified Smith delay compensator for controlling nonsquare MIMO process is proposed. The proposed structure is designed with two disturbance estimators and a setpoint tracking controller. The estimators reject the disturbances in the forward path. These estimators also take part in delay compensation. The design of setpoint tracking controllers and disturbance estimators uses simple mathematical calculations as compared to the conventional IMC-based controllers. In the proposed design, Grey wolf optimization technique has been used to optimize the predictor. The closed-loop system produces the desired servo and regulatory response. The internal stability and robustness of the proposed MIMO cascade control structure have been analyzed. An example of a physical process has been included to illustrate the novelty of the proposed control strategy over multivariable PID controllers in terms of the time-domain performance and delay compensation. query Please check the edit made in the article title. [ABSTRACT FROM AUTHOR]

Current link state routing is based on routing decisions made through distributed interactions among routers. Link state is disseminated by means of flooding, which possesses a few limitations, such as excessive message overhead and network-wide computation. Thus, we propose LSC, an extended link state routing protocol with centralized control, in this paper to address this problem. In LSC, link state advertisements (LSAs) are communicated between a centralized element (CE) and a forwarding engine (FE) rather than traditional flooding. Multiple CEs form a separate control network as a representation of the control plane. Through this control network, LSAs are disseminated to FEs in a determinate manner. We also propose a signaling protocol for independent path convergence in the control network, as well as a routing control algorithm to prevent unnecessary routing updates in the forwarding network. We implement a prototype LSC and evaluate its performance. Our experiments show that with the use of real topologies, LSC can accelerate network convergence and reduce message overhead compared with OSPF. Moreover, LSC is robust because having multiple CEs can prevent the occurrence of a single point of failure. LSC also scales well with network size by adding additional CEs to share in the processing load. [ABSTRACT FROM AUTHOR]

The power system is presently experiencing vital changes: it is advancing from a centralized structure to a decentralized one, primarily because of the enormous advancement of distributed renewable energy sources, so future power system obliges new control strategies. These systems must have the capacity to withstand new requirements, for example, the exceedingly disseminated nature, the irregularity of renewable energy sources and the restricted data transfer capacity for communications. Multi agent systems (MAS) have attributes that meet these prerequisites. A certain degree of distributed or collective intelligence can be accomplished through the connection of these agents with one another, participating or contending to achieve their objectives. This paper introduces outline of the fundamental ideas of MAS and its different platforms. Also, it provides a comprehensive survey on the power system applications in which MAS technique has been applied. For each power system application, technical details are also discussed. [ABSTRACT FROM AUTHOR]

With an increasing number of assistive robots operating in human domains, research efforts are being made to design control systems that optimize the efficiency of multi-robot operations. As part of the EU funded RoboEarth project, this paper discusses the design of such a system, where a variety of existing components are selected and combined into one cohesive control architecture. The architecture's main design principle stems from Radestock's 'separation of concerns', which dictates the separation of software architectures into four disjunct components; coordination, configuration, communication and computation. For the system's coordinating component a Golog based planning layer is integrated with a custom made execution module. Here, the planning layer selects and parametrizes abstract action plans, where the execution layer subsequently grounds and executes the involved actions. Plans and plan related context are represented in the OWL-DL logics representation, which allows engineers to model plans and their context using first-order logic principles and accompanying design tools. The communication component is established through the RoboEarth Cloud Engine, enabling global system accessibility, secure data transmissions and the deployment of heavy computations in a Cloud based computing environment. We desire these computations, such as kinematics, motion planning and perception, to all run on the Cloud Engine, allowing robots to remain lightweight, the instant sharing of data between robots and other algorithms and most importantly, the reuse of these algorithms for a variety of multi-robot operations. A first design of the system has been implemented and evaluated for its strengths and weaknesses through a basic, but fundamental real-world experiment. [ABSTRACT FROM AUTHOR]

When the traditional RRT algorithm is used to control the position of the legged robot synchronously, its adaptability is poor and it is easy to be disturbed by the surrounding environment, which leads to the low stability of the robot when avoiding obstacles. The position synchronization control algorithm of the legged robot based on DSP centralized control is proposed. The parameter on-line fuzzy self-tuning PID algorithm is used in the position loop of the control system of the robot car controller to improve the adaptive ability of the robot. The inverse Fourier transform of cross power spectrum is used to determine the position and orientation angle of the robot, and the displacement theorem of the robot is used to control the position of the robot synchronously. The experimental results show that the proposed algorithm can effectively synchronize and control the robot running safely and accurately in obstacle-free environment. The average time is 18 s, the maximum robustness is 0.45, and the maximum control error rate is 0.25. It has the advantages of high control efficiency, high robustness and small error, which ensures the stable operation of the robot. [ABSTRACT FROM AUTHOR]

This manuscript presents an application of the multi-layer control scheme to guide a formation of unmanned aerial vehicles (UAV) in positioning and trajectory tracking missions. In such case, each part of the formation control problem is dealt by an individual layer, which is independent module dealing with a specific part of the navigation problem. These layers are responsible to generate the desired path of the formation, to provide the desired posture of the robots, and to establish the control signal of each robot to reach their desired positions. The formation controller here introduced is able to coordinate the robots to the desired formation, including the possibility of time-varying position and/or shape, while a nonlinear underactuated controller previously proposed is responsible to guide the UAVs to their desired positions. The stability analysis of the closed-loop system is demonstrated in the sense of Lyapunov, resulting that the formation errors are ultimately bounded. In the sequel, a strategy to guide a formation of multiple unmanned aerial vehicles (MUAV) to accomplish positioning and trajectory-tracking tasks is also proposed. Delaunay triangulation is here used to split the platoon of UAVs in N-triangles, which are individually guided by the multi-layer control scheme (MLCS). The advantage of the MLCS in such proposal is the maintenance of the the Jacobian matrix order, regardless of the number of robots in the formation, which reduces the complexity of the control problem. Simulation results demonstrate the ability to accomplish the aforementioned tasks, thus validating the proposal. [ABSTRACT FROM AUTHOR]

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The behavior of a net of interconnected, communicating processes is described in terms of the joint actions in which the processes can participate. A distinction is made between centralized and decentralized action systems. In the former, a central agent with complete information about the state of the system controls the execution of the actions; in the latter no such agent is needed. Properties of joint action systems are expressed in temporal logic. Centralized action systems allow for simple description of system behavior. Decentralized (two-process) action systems again can be mechanically compiled into a collection of CSP processes. A method for transforming centralized action systems into decentralized ones is described. The correctness of this method is proved, and its use is illustrated by deriving a process net that distributedly sorts successive lists of integers. [ABSTRACT FROM AUTHOR]