Flexible Control System Research Articles

Evolution of holonic control architectures towards Industry 4.0: A short overview

The flexibility claimed by the next generation production systems induces a deep modification of the behavior and the core itself of the control systems. Overconnectivity and data management abilities targeted by Industry 4.0 paradigm enable the emergence of more flexible and reactive control systems, based on the cooperation of autonomous and connected entities in the decision making process. For the last 20 years, holonic paradigm has become the core paradigm of those evolutions, and evolved in itself. This contribution aims at emphasizing the conceptual evolutions in the application of holonic paradigm in the control architectures of manufacturing systems and highlighting the current research trends in this field.

Embedded and Flexible Image File Version Control System for Managing Multiple Minor Changes

Embedded and Flexible Image File Version Control System for Managing Multiple Minor Changes

Robust finite-time non-fragile sampled-data control for T-S fuzzy flexible spacecraft model with stochastic actuator faults

In this paper, the problem of robust finite-time non-fragile sampled-data control is investigated for uncertain flexible spacecraft model with stochastic actuator faults based on Takagi-Sugeno (T-S) fuzzy model approach. Specifically, the existence of stochastic actuator faults are described by using the Bernoulli distribution. On the basis of the input-delay approach, the sampled-data system is reformulated to a continuous time-varying delay system. Further, based on Lyapunov functional approach and linear matrix inequality technique, sufficient conditions are derived for the existence of the desired state feedback controller ensuring the stochastic finite-time bounded with prescribed H∞ performance index. Finally, numerical simulations are provided for the practical flexible spacecraft control system to verify the effectiveness and applicability of the proposed control design.

Control system for a carbon fiber plate using an adaptive negative derivative feedback control algorithm

Active vibration control of flexible systems is still an open issue. Among the different techniques developed during the last decades resonant controllers are becoming more and more attractive. They concentrate the feedback action in a particular frequency range, optimizing the control effort and minimizing the spillover effect on nonmodeled dynamics. In particular, negative derivative feedback (NDF), feeding back the velocity through a modal compensator, reduces spillover at frequencies both lower and higher than the desired range of interest. Starting from this approach, the possibility to create a smart structure able to adapt the control parameters to the vibration characteristics represents a very promising solution. A NDF adaptive control logic has been designed and analyzed, both numerically and experimentally, on a carbon fiber plate test rig.

A flexible control system designed for lab-scale simulations and optimization of composting processes

Understanding and optimization of composting processes can benefit from the use of controlled simulators of various scales. The Agricultural Research Organization Composting Simulator (ARO-CS) was recently built and it is flexibly automated by means of a programmable logic controller (PLC). Temperature, carbon dioxide, oxygen and airflow are monitored and controlled in seven 9-l reactors that are mounted into separate 80-l water baths. The PLC program includes three basic heating modes (pre-determined temperature profile, temperature-feedback (“self-heating”), and carbon dioxide-dependent temperature), three basic aeration modes (airflow dependence on temperature, carbon dioxide, or oxygen) and enables all possible combinations among them. This unique high flexibility provides a robust and valuable research tool to explore a wide range of research questions related to the science and engineering of composting. In this article the logic and flexibility of the control system is presented and demonstrated and its potential applications are discussed.

Intelligent Traffic Light Based on PLC Control

The traditional traffic light system with a fixed control mode and single control function is contradicted with the current traffic section. The traditional one has been unable to meet the functional requirements of the existing flexible traffic control system. This paper research and develop an intelligent traffic light called PLC control system. It uses PLC as control core, using a sensor module for receiving real-time information of vehicles, traffic control mode for information to select the traffic lights. Of which control mode is flexible and changeable, and it also set the countdown reminder to improve the effectiveness of traffic lights, which can realize the goal of intelligent traffic diversion, intelligent traffic diversion.

Vibration suppression-based attitude control for flexible spacecraft

In this paper, a novel approach for high-accuracy attitude control in a flexible spacecraft is developed by compensating and damping the vibration of the flexible appendage. A vibration suppression-based attitude controller (VSAC) that addresses the coupling disturbance in attitude dynamics that is generated by the vibration of the flexible appendage is developed for flexible spacecraft. The proposed VSAC integrates the existing attitude control theories with vibration suppression control strategies by combining a time delay feedback controller with a PD controller. The stability of the flexible spacecraft control system under the proposed VSAC is investigated in time domain, and the damping effect of the proposed VSAC on the vibration of the flexible appendage is analyzed in frequency domain. The proposed VSAC utilizes the traditional attitude controller and vibration suppression controller, which can not only effectively improve the performance of attitude control system but also efficiently damp the vibration of the flexible appendage. Finally, numerical simulations are performed, and analysis and conclusions are presented.

Data-Based Tuning of Reduced-Order Inverse Model in Both Disturbance Observer and Feedforward With Application to Tray Indexing

Performance of traditional model-based control relies upon accurate modeling. In motion control of flexible systems, it is desirable to use the reduced-order model for ease of trajectory planning and pole placement, but its performance is constrained by modeling inaccuracies due to the existence of friction and multiple flexible modes. To improve the tracking performance, we have developed a data-based method for iterative tuning of the parameters in the reduced-order inverse model within a three-degree-of-freedom composite control structure. The proposed method solely makes use of the input-output data obtained during closed-loop experiments to fine-tune the inverse system model, and accurate system modeling is not required. Unbiasedness of the cost function gradient estimation is proven under reasonable assumptions of stochastic properties of the perturbations. Simulation and experiments are conducted to further illustrate the proposed method and show its practical appeals in industrial applications.

The Model and Parameters Based on the Operation Mode of a 500kV Multi-terminal Flexible DC Power Grid

The operating conditions of 500kV Zhangjiakou-Beijing Demonstration Project at all operation modes were studied regarding a multi-terminal flexible DC system with DC switches and a true bipolar wiring method. Based on the actual AC-DC hybrid method, this paper concluded 34 kinds of N-1 operation modes for keeping the system stable, simulated the multi-level converter valve (MMC) bank by using RTDS small-step elements, adopted an ideal voltage balancing method for the treatment of sub-units and established a MCC system simulating structure in compliance with the site. The operation modes of the system were simulated by selecting the parameters which are consistent with the line, using such parameters as the actual configurations and parameters of key elements such as the converter transformer, filter, bridge arm reactor, converter, etc. adopted in the project, and establishing a flexible DC control system with a layered structure. According to the result of the simulation, the corresponding modes of the system were provided and references were given for the feasibility study and implementation of the project.

Construction and experimental verification of a novel flexible thermal control system configuration for the autonomous on-orbit services of space missions

This paper proposed a novel flexible thermal control system (F-TCS) configuration for realizing thermal management for spacecrafts autonomous on-orbit service (A-OOS) demands. With a dual-ring topology which composes of a heat collecting bus, a heat dissipating bus, connection brunches and inter-platform service interfaces, the F-TCS may realize not only self-reconfiguration operations but also providing heat dissipation resources for other spacecrafts or cabins. The F-TCS hydraulic and thermal dynamics were modeled, a verification testbed was also established to validate the F-TCS thermal control performance. Focused on investigating the self-reconfiguration and thermal control cooperative operations, several typical A-OOS cases were imposed on the F-TCS, numerical simulations and experimental validations were respectively implemented. Both results demonstrated that the meticulously designed F-TCS is capable of offering self-topological reconfiguration with fast time response and robust temperature control performances, high systemic heat transfer efficiency is also recommended from the point of view of energy saving. The F-TCS is suggested as a promising solution for A-OOS owing to its higher reliability and promising autonomous maintenance potential which is suitable for future spacecrafts thermal management requirements.

Development of an optimal control scheme for the process of epoxy resins modification with a complicated mathematical model in the control loop.

The problem of optimal control for a highly exothermal technological process with distributed state variables and with a large dead time is discussed. The main steps of creating a flexible control system with using the object model in the control loop are considered. It is shown that heat flux calorimetry is an effective experimental technique for the development of a process model based upon corresponding multistage kinetic model. It can be also applied to multiphase reaction systems together with simplified hydrodynamic models for mass transfer phenomena description. A successful application of this approach for developing the process mathematical model and its further introduction to the corresponding control system has been demonstrated for an important industrial process ? modification of epoxy resins with butanediol-1,4 for further synthesis of epoxy-urethane polymers with improved physico-chemical and mechanical properties. The process mathematical model makes it possible to specify the optimal operating mode for each resin and implement the optimal control.

Wake-up timer and binary exponential backoff for ZigBee-based wireless sensor network for flexible movement control system of a self-lifting scaffold

Synchronous movement of attached self-lifting scaffolds is traditionally monitored with wired sensors in high-rise building construction, which limits their flexibility of movements. A ZigBee-based wireless sensor system has been suggested in this article to prove the effectiveness of wireless sensor networks in actual implementation. Two optoelectronic sensors are integrated into a ZigBee node for measuring the displacement of attached self-lifting scaffolds. The proposed wireless sensor network combines an end device and a coordinator to allow easy replacement of sensors as compared to a wired network. A wake-up timer algorithm is proposed to reduce the transmitting power during continuous wireless data communication in the wireless sensor network. Furthermore, a variant binary exponential backoff transmission algorithm for data loss avoidance is proposed. The variant binary exponential backoff algorithm reduces packet collisions during simultaneous access by increasing the randomizing moments at nodes attempting to access the wireless channels. The performance of three of the proposed modules—a cable sensor, a 315-MHz sensor, and a ZigBee sensor—is evaluated in terms of packet delivery ratio and the end-to-end delay of a ZigBee-based wireless sensor network. The experimental results show that the proposed variant binary exponential backoff transmission algorithm achieves a higher packet delivery ratio at the cost of higher delays. The average cost of the developed ZigBee-based wireless sensor network decreased by 24% compared with the cable sensor. The power consumption of ZigBee is approximately 53.75% of the 315-MHz sensor. The average current consumption is reduced by approximately 1.5 mA with the wake-up timer algorithm at the same sampling rate.

Automated microbeam observation environment for biological analysis—Custom portable environmental control applied to a vertical microbeam system

Vertical Microbeams (VMB) are used to irradiate individual cells with low MeV energy ions. The irradiation of cells using VMBs requires cells to be removed from an incubator; this can cause physiological changes to cells because of the lower CO2 concentration, temperature and relative humidity outside of the incubator. Consequently, for experiments where cells require irradiation and observation for extended time periods, it is important to provide a controlled environment. The highly customised nature of the microscopes used on VMB systems means that there are no commercially available environmentally controlled microscope systems for VMB systems. The Automated Microbeam Observation Environment for Biological Analysis (AMOEBA) is a highly flexible modular environmental control system used to create incubator conditions on the end of a VMB. The AMOEBA takes advantage of the recent “maker” movement to create an open source control system that can be easily configured by the user to fit their control needs even beyond VMB applications. When applied to the task of controlling cell medium temperature, CO2 concentration and relative humidity on VMBs it creates a stable environment that allows cells to multiply on the end of a VMB over a period of 36h, providing a low-cost (costing less than $2700 to build), customisable alternative to commercial time-lapse microscopy systems. AMOEBA adds the potential of VMBs to explore the long-term effects of radiation on single cells opening up new research areas for VMBs.

Optimal assembly of a skin panel onto the fuselage framework based on force control technology

It is important for fuselage assembly to align the skin panel onto the frame, i.e. to reduce the gaps and subsequently lessen the need for shimming, but conventional position control method cannot always meet the requirement. This study proposed a direct force control technology, which can be directly promoted to a full-rate production without making any dedicated assistance and complex finite element analysis. This strategy was based on a force sensor mounted on a flexible tooling locator to feed back the pressing force information to the controller system. To achieve a certain compressing status, the system was controlled to achieve a desired force rather than reach a specific position. After obtaining four ideal force values from an experimental study during a prototype trial-production, a force-size interval that provides a certain grey degree of confidence was proposed for the flexible tooling control system using a parameter estimation approach for small samples based on the grey distance measure. Compared with conventional position control method, force control technology can achieve better compressing status, since it enables a reduction of all gap values between the skin panel and the framework by 0.15 mm on average or even 0.2 mm at most in the same assembly process.

Design and Human-in-the-Loop Testing of Reduced-Modification Input Shapers

Many systems require a human in the control loop. When the controlled system has flexibility, the human can have significant difficulties operating the machine. Input-shaping control has been shown to improve the control of flexible systems by reducing system vibration. However, it may negatively affect the control of the driven base or vehicle that the operator is directly controlling. This brief presents a new type of input shaper that modifies the operator's command less than traditional input shapers, thereby improving the control of the driven base. A manual tracking experiment compared the tracking performance and subjective difficulty using both the new and traditional input shapers. Input shapers generally improved the tracking performance of the system's flexible element, and the new input shapers did not significantly degrade tracking of the system’s driven base.

SMS Controlled Smart Home System In IOT

This paper describes the design and development of a system that incorporates a low-cost and flexible home control and monitoring system for accessing and controlling household appliances (like lights, fans, door locks, etc., ) remotely by sending SMS using a custom made Android Smart Phone Application. The cellular communication (GSM) is a potential solution for such remote controlling activities. Remotely, the system allows the home owner to monitor and control the home appliances via mobile phone set by sending commands in the form of SMS messages. The system uses the Android Application for control of appliances and therefore the system is more adaptable and cost-effective and also providing ubiquitous access for appliance control.

Active vibration suppression in flexible spacecraft with optical measurement

With the development of the space station technology in China, the active vibration suppression of the lager flexible antennas and solar panels that mounted on the space station is demanded. The active vibration suppression is hard to achieve because these appendages are not allowed to mount actuators on it. Further, the practical goal is usually unachievable by the controller based on the unreliability or impracticality observed vibration parameters. In this paper, the active vibration suppression during the spacecraft attitude maneuver by the optical camera monitoring the dynamic behaviors of the flexible appendages is introduced under the restriction of the freedom of the actuators. The modal parameters of the flexible appendage used in the controller are obtained by the optical monitoring approach. A referenced angular velocity is set as the virtual input by the back-stepping control and Lyapunov method, and the control law is designed to track this virtual input. The constraint of the coefficient in the controller is investigated to guarantee the asymptotic convergence of the system considering angular velocity tracking error. The control manage coefficient is defined to describe the distribution coefficient of the vibration suppression in the design of control law. The relationship between the attitude maneuver accuracy and active vibration suppression is introduced. The appropriate control manage coefficient is obtained numerically. To guarantee the reliability or practicality of the designate flexible spacecraft control system, the optical measurements are used to measure the dynamic behaviors of the large flexible structures. The absence of displacement velocity sensors is compensated by the presence of appropriate dynamics in the controller. The results of simulation validate the feasibility of the proposed control strategy.

Analysis of the innovative environment of the industrial enterprise

In conditions of economic instability of one of the major problems facing managing subjects, creation of a flexible control system capable to restructuring and orientation to stable progress is. Finding of flexibility is impossible without use of system of monitoring and an assessment of a level of development of the enterprise that allows to estimate influence of internal factors of progress of the organization on its position in an environment, as well as to make a decision on duly variation of the mechanism of operation of business. Innovative activity differs integrated approach, and, consequently, mechanisms of interoperability are necessary for realization of operative management of her between the various structural divisions involved in innovative process. One of such mechanisms is the analysis of the innovative environment. Feature of the analysis of the innovative environment as tool of management of progress of the enterprise is concentration on revealing of tendencies and dynamics of progress that distinguishes it from the controlling aimed at result. The essence of the analysis consists in regular tracking results of financial and economic activity and its correction within the limits of the scheduled (design) period. By development and realization of strategy of innovative progress monitoring acts as the mechanism of coordination of actions of all involved structural divisions of the managing subject. Thus, it is possible to present the analysis of innovative progress of the enterprise as continuous supervision over a condition of the external both internal environment and processes of financial and economic activity of the enterprise with objective of the prevention of undesirable deviations on the major parameters of economic progress. The assessment of structure of the innovative environment of the enterprise will allow to analyze, first of all, financial capacity of the enterprise to innovative progress, to check correctness of the chosen direction of progress from positions of a modern and further financial condition of the enterprise. The generated procedure can become a substantial basis of formation of strategy of innovative progress and payment of new technologies. The enterprises will have effective toolkit of an assessment of innovative possibilities, as well as a choice of possibly sold strategy of progress.

Integrated Flexible Maritime Crane Architecture for the Offshore Simulation Centre AS (OSC): A Flexible Framework for Alternative Maritime Crane Control Algorithms

The Offshore Simulator Centre AS (OSC) is the world's most advanced provider of simulators for demanding offshore operations. However, even though the OSC provides very powerful simulation tools, it is mainly designed for training purposes and it does not inherently offer any flexible methods concerning the control methodology. In fact, each crane model is controlled with a dedicated control algorithm that cannot be modified, accessed, or replaced at runtime. As a result, it is not possible to dynamically switch between different control methods, nor is it possible to easily investigate alternative control approaches. To overcome these problems, a flexible and general control system architecture that allows for modeling flexible control algorithms of maritime cranes and more generally, robotic arms, was previously presented by our research group. However, in the previous work, a generic game engine was used to visualize the different models. In this work, the flexible and general control system architecture is integrated with a crane simulator developed by the OSC taking full advantage of the provided domain-consistent simulation tools. The Google Protocol Buffers protocol is adopted to realize the communication protocol. This integration establishes the base for the research of alternative control algorithms, which can be efficiently tested in a realistic maritime simulation environment. As a validating case study, an alternative control method based on particle swarm optimization (PSO) is also presented. Related simulations are carried out to validate the efficiency of the proposed integration.

An improved recursive least square–based adaptive input shaping for zero residual vibration control of flexible system

In this article, a promoted method of adaptive input shaping based on recursive least square with forgetting factor is proposed to achieve zero residual vibration of time-varying flexible systems. First, the zero residual vibration condition of the flexible system is reviewed. Then, the mathematical analysis of recursive least square–based adaptive input shaping is presented; it can be seen that the traditional recursive least square method could calculate the least square solution with all historical I/O data. That is to say, with the increase in time and larger amount of I/O data, the current data could hardly affect the results of the updated input shapers’ coefficients; thus, the problems of insufficient adaptability and noise accumulation occur. So, a forgetting factor is introduced in the recursive calculation to give less calculation weight on historical data and improve the sensitivity of the current data; thus, the above-mentioned problem could be significantly avoided. At last, the verification experiments of adaptive input shaping are implemented on a two-link flexible manipulator, which is a classical flexible system with severely time-varying dynamics; the results validate the effectiveness of the improved adaptive input-shaping method for the vibration control of these flexible systems.