Flexible Control Architecture Research Articles

Flexible and High-Precision Integration of Inserts by Combining Subtractive and Non-Planar Additive Manufacturing of Polymers

Additive manufacturing of polymers offers great potential for the production of complex structures. In particular, Fused Filament Fabrication (FFF) processes can be used to create functionally integrated components, in addition to easy handling, tool-free production and large material options. By combining a FFF system with a robot, inserts of different types can be integrated automatically during the printing process [1]. The low dimensional accuracy of FFF induces great difficulties during the insertion operation. Furthermore, with FFF, a planar layer structure leads to a stair-step effect when overprinting inserts with curved outer contours and reduces the adhesion to the insert. Further, the adhesion of FFF-filaments to the insert depends on the surface treatment of the insert [1]. A FFF system was combined with a robot [2] and has now been expanded to include a subtractive finishing unit and an inline process control based on a machine vision system, which enables the dimensional accuracy of the FFF components to be checked during the printing process. To be able to produce functionally integrated components, a flexible control architecture is being developed that enables the execution of additive and subtractive process steps. Optimal integration of inserts with complex geometries is facilitated by using non-planar layers in the FFF path planning. For this purpose, the filament layers of the FFF components follow the tilted or curved contours of the inserts. The modified process is demonstrated by manufacturing an integrated stator for an electric motor. A system for an additive-subtractive process for the integration of functional inserts was developed. In addition, a concept for the implementation of an improved connection of the inserts through non-planar FFF layers was created. First steps for the integration of the various system-modules and optical analysis of the dimensional accuracy and the development of a printing strategy for non-planar overprinting of the inserts have been realized.

Enhancing bioreactor arrays for automated measurements and reactive control with ReacSight

Small-scale, low-cost bioreactors provide exquisite control of environmental parameters of microbial cultures over long durations. Their use is gaining popularity in quantitative systems and synthetic biology. However, existing setups are limited in their measurement capabilities. Here, we present ReacSight, a strategy to enhance bioreactor arrays for automated measurements and reactive experiment control. ReacSight leverages low-cost pipetting robots for sample collection, handling and loading, and provides a flexible instrument control architecture. We showcase ReacSight capabilities on three applications in yeast. First, we demonstrate real-time optogenetic control of gene expression. Second, we explore the impact of nutrient scarcity on fitness and cellular stress using competition assays. Third, we perform dynamic control of the composition of a two-strain consortium. We combine custom or chi.bio reactors with automated cytometry. To further illustrate ReacSight’s genericity, we use it to enhance plate-readers with pipetting capabilities and perform repeated antibiotic treatments on a bacterial clinical isolate.

Nonconservative Distributed Control Over Real-Time Network Links

Communication technologies are being continuously developed to provide improved support of real-time links for an industrial Internet of Things. This article considers a general and flexible distributed control architecture over real-time links. No bounds are assumed on the value of delays that are modeled as random variables. An accurate modeling and analysis framework is provided and the exact value of a control performance cost function is calculated. The results provide the required tools for optimization-based design of distributed networked control systems. A case study is presented in which networked controllers are designed based on the consensus algorithm for coordination of multiple parallel power electronic converters. It is shown that consideration of the communication effects in the controller design process is crucial for achieving superior performance.

A Coalitional Distributed Model Predictive Control Perspective for a Cyber-Physical Multi-Agent Application.

Following the current technological development and informational advancement, more and more physical systems have become interconnected and linked via communication networks. The objective of this work is the development of a Coalitional Distributed Model Predictive Control (C- DMPC) strategy suitable for controlling cyber-physical, multi-agent systems. The motivation behind this endeavour is to design a novel algorithm with a flexible control architecture by combining the advantages of classical DMPC with Coalitional MPC. The simulation results were achieved using a test scenario composed of four dynamically coupled sub-systems, connected through an unidirectional communication topology. The obtained results illustrate that, when the feasibility of the local optimization problem is lost, forming a coalition between neighbouring agents solves this shortcoming and maintains the functionality of the entire system. These findings successfully prove the efficiency and performance of the proposed coalitional DMPC method.

Evaluation of process control architectures for agile manufacturing systems

Current manufacturing systems are faced with a rapidly changing environment caused by customization, which leads to smaller lot sizes. The answer to this challenging situation are agile production systems, which are able to react to new tasks very quickly. One major aspect for realizing such systems is a flexible control architecture for orchestration of machine tending tasks. The aim of this paper is to compare different approaches currently developed and applied in research and industry, e.g. centralized cloud control or head control by a master device. For evaluation, suitable requirements are determined with respect to current limitations and implementation effort.

A Biomimetic Control Method Increases the Adaptability of a Humanoid Robot Acting in a Dynamic Environment.

One of the big challenges in robotics is to endow agents with autonomous and adaptive capabilities. With this purpose, we embedded a cerebellum-based control system into a humanoid robot that becomes capable of handling dynamical external and internal complexity. The cerebellum is the area of the brain that coordinates and predicts the body movements throughout the body-environment interactions. Different biologically plausible cerebellar models are available in literature and have been employed for motor learning and control of simplified objects. We built the canonical cerebellar microcircuit by combining machine learning and computational neuroscience techniques. The control system is composed of the adaptive cerebellar module and a classic control method; their combination allows a fast adaptive learning and robust control of the robotic movements when external disturbances appear. The control structure is built offline, but the dynamic parameters are learned during an online-phase training. The aforementioned adaptive control system has been tested in the Neuro-robotics Platform with the virtual humanoid robot iCub. In the experiment, the robot iCub has to balance with the hand a table with a ball running on it. In contrast with previous attempts of solving this task, the proposed neural controller resulted able to quickly adapt when the internal and external conditions change. Our bio-inspired and flexible control architecture can be applied to different robotic configurations without an excessive tuning of the parameters or customization. The cerebellum-based control system is indeed able to deal with changing dynamics and interactions with the environment. Important insights regarding the relationship between the bio-inspired control system functioning and the complexity of the task to be performed are obtained.

Event-driven industrial robot control architecture for the Adept V+ platform.

Modern industrial robotic systems are highly interconnected. They operate in a distributed environment and communicate with sensors, computer vision systems, mechatronic devices, and computational components. On the fundamental level, communication and coordination between all parties in such distributed system are characterized by discrete event behavior. The latter is largely attributed to the specifics of communication over the network, which, in terms, facilitates asynchronous programming and explicit event handling. In addition, on the conceptual level, events are an important building block for realizing reactivity and coordination. Event-driven architecture has manifested its effectiveness for building loosely-coupled systems based on publish-subscribe middleware, either general-purpose or robotic-oriented. Despite all the advances in middleware, industrial robots remain difficult to program in context of distributed systems, to a large extent due to the limitation of the native robot platforms. This paper proposes an architecture for flexible event-based control of industrial robots based on the Adept V+ platform. The architecture is based on the robot controller providing a TCP/IP server and a collection of robot skills, and a high-level control module deployed to a dedicated computing device. The control module possesses bidirectional communication with the robot controller and publish/subscribe messaging with external systems. It is programmed in asynchronous style using pyadept, a Python library based on Python coroutines, AsyncIO event loop and ZeroMQ middleware. The proposed solution facilitates integration of Adept robots into distributed environments and building more flexible robotic solutions with event-based logic.

Source-load-storage consistency collaborative optimization control of flexible DC distribution network considering multi-energy complementarity

Due to the increasing coupling degree of the power network, natural gas network, and thermal network, this paper discusses a flexible DC power distribution network based on the consistency algorithm theory regarding the advantages and disadvantages of centralized control and distributed control. A layered network control architecture is presented. Considering the multi-time-scale control characteristics of the system, the control architecture is divided into three layers: energy management layer, bus control layer, and converter control layer. In the energy management layer, the dispatch optimization center optimizes the system operating cost through the multi-objective energy optimization management of the integrated energy system consisting of the DC distribution network, natural gas network, and heating network. In the bus control layer, the DC bus voltage is taken into account. The control characteristics are divided into three categories corresponding to three working modes according to the range of the DC bus voltage, which is used to realize the conversion mode control of every distributed device in the distribution network. In the converter control layer, based on the original droop control, the voltage and frequency deviations of every distributed device are compensated twice, and every distributed device controller communicates only with the adjacent controller to achieve the voltage and frequency consistency control with the “virtual leader” node. Finally, using the typical eight-terminal VSC flexible DC distribution network control architecture, the proposed control strategy is verified by the PSCAD/EMTDC simulation software.

Internet‐based operation of autonomous robots: The role of data replication, compression, bandwidth allocation and visualization

AbstractThe problem of remote‐controlling a mobile robot through the Internet with its associated bandwidth constraints is addressed in this paper. Our solution combines a novel communication and processing module with a unique sensor layout and a flexible control architecture to achieve a range of capabilities from traditional teleoperation to point‐and‐click autonomy. Careful management of the available bandwidth enables a demonstration of these capabilities between nodes with 20,000 km separation while also providing real‐time three‐dimensional (3D) models of the environment through the Internet. A spatially oriented compression algorithm, integral to efficient bandwidth management, is also presented. Experiments establish the effectiveness of the extended situational awareness in improving the efficiency and accuracy of driving a mobile robot through a cluttered environment over the existing 2D map or video streaming methods. © 2012 Wiley Periodicals, Inc.

Requirement analysis for autonomous systems and intelligent agents in future Danish electric power systems

Denmark has already achieved a record of 20% penetration of wind power and now moving towards even higher targets with an increasing part of the electricity produced by distributed generators (DGs). In this paper we report work from a sub activity subgrid design of the EcoGrid.dk1 project. First we review innovative control architectures in electric power systems such as Microgrids, Virtual power plants and Cell based systems. We evaluate application of autonomous systems and intelligent agents in each of these control architectures particularly in the context of Denmark's strategic energy plans. The second part formulates a flexible control architecture for electric power systems with very high penetration of distributed generation. This control architecture is based upon the requirements identified in the first part. We also present development of a software framework to test such flexible control architectures. Keywords: Electric power system, distributed control, autonomous systems, intelligent agents

A flexible control architecture for extended autonomy of robotic assistants

A major challenge in deploying robots into the real world is the design of an architectural framework which can provide extended, natural and effective interactions with people. Within this framework, key issues that need to be solved relate to the robots’ ability to engage in interactions in a natural way, to deal with multiple users, and to be continually perceptive of their surroundings. In this paper we propose a robot control architecture that addresses these issues. Our architecture has three main key features. First, it enables the representation of complex, sequential and hierarchical robot tasks, typically needed for service applications, in a behavior-based framework. Second, it provides the robot with flexibility in dealing with multiple users, such as to accommodate multiple user requests and task interruptions, over extended periods. Third, through its visual detection mechanism, the architecture allows the robot to identify when people are requesting its interaction. We demonstrate our approach on a Pioneer 3DX mobile robot, performing service tasks in a real-world environment.

Automated Nano-Assembly in the SEM I: Challenges in setting up a warehouse

This paper describes the implementation of setting up a warehouse for automated nano-assembly, i.e. the automated registration of the parts processed during the automated assembly. Starting with a brief description of the goals of the assembly process, the overall process structure and its challenges with respect to the micro- and nanoscale are explained. The warehouse task is used as an example for describing the task planning, the necessity to minimize the number of subtasks taking further constraints from the experimental setup into account. For controlling such a complex assembly process, an intelligent and flexible control and communication system architecture is necessary, which will be explained in detail. Based on these considerations, the implementation of the warehouse task and its challenges, including the representation of the parts in the control system, object recognition using generalized models and methods for part origin determination will be presented.

A system architecture for holonic manufacturing planning and control (EtoPlan)

In this paper, we present the system architecture of a flexible manufacturing planning and control system, named EtoPlan. The concept is based on the holonic control approach of building multiple and temporary hierarchies (holarchies). This paper describes the system architecture for flexible planning and control of activities and (groups of) Resources in a manufacture-to-order environment. The system architecture consists of generic control modules that can be applied on different hierarchical levels and for different kinds of manufacturing activities. The main function of the Resource Controller is the Determine Applicability function.

Metabolic engineering from a cybernetic perspective. 2. Qualitative investigation of nodal architechtures and their response to genetic perturbation

A cybernetic representation of the branch point development of Stephanopoulos and Vallino is formulated. The model systems are employed to translate the qualitative properties of the nodal control architectures characterized by Stephanopoulos and Vallino into a mathematical context. It is shown that a cybernetic model in which the objective is the independent maximization of the levels of branch point products is consistent with the characterization of a flexible node. In contrast, the rigid control architecture is shown to be equivalent to the maximization of the mathematical product of the branch point products. It has been demonstrated subsequently that cybernetic metabolic network models are capable of predicting the system response to enzymatic amplification. However, given the complicated nature of the subsequent models, a clear illustration of the basic mechanism by which such predictions are manifested is not forthwith. Thus, a second objective of the present work is the examination of the response of the flexible and rigid control architectures to genetic perturbation, specifically enzymatic overexpression, with the expressed aim of elucidating the mechanism by which a cybernetic model predicts metabolic network responsiveness. It is shown that the ramifications of genetic perturbation are transmitted through the cybernetic representation of a metabolic network via the resource allocation structure which acts as the conduit by which regulatory signals are transmitted to seemingly unconnected portions of the network. It is postulated that enzymatic overexpression under an artificial promoter represents, from the perspective of the microorganism, an uncontrollable resource drain that forces the metabolic network control architecture to reevaluate the standing resource allocation policy as implemented via the cybernetic control variables. In biological terms, the reevaluation of allocation policy implies a shift in the level and activity of network enzymes yielding, in some cases, qualitatively different network function. It is our position that, conceptually, this is equivalent to the conventional wisdom that genetic manipulation of a metabolic network is the impetus for shifts in the network functionality, i.e., enzyme levels as well as activity. Thus, this development provides a necessary intellectual precursor for the formulation and analysis of the model systems that follow.

Integration of an open architecture controller with a diamond turning machine

Older machine tools are often mechanically sound but their proprietary controls are outdated and can be economically upgraded to modern open architecture control. The objective of this paper is to present a procedure for integrating these new flexible control architectures into machine tools. As an example, this paper presents the integration of an open architecture controller and a diamond turning machine. The open architecture control permits research into various types of control such as position, velocity, force, and adaptive control that will improve the quality of manufactured optics and other high precision components. The goal of incorporating an open architecture controller into an existing diamond turning machine required the identification, integration and installation of many components. After installing these components, the machine was calibrated to improve its performance. The most important aspect in improving the overall performance of the machine was correcting its vibration characteristics. Spindle imbalance, the spindle shaft coupler and the table and slide amplifiers were found to play a significant role in producing vibration. The sidewise amplitude of acceleration was reduced from approximately 2.5 to 0.6 g due to reduction in vibration after correcting these sources. The remaining level of vibration is normal for this type of diamond turning machine allowing it to produce finishes with 90.24 nm (3.56 μin) RMS surface roughness using a radius tool and 24.13 nm (0.95 μin) RMS with the straight-edge tool.

A distributed control architecture for autonomous mobile robots - implementation of the Karlsruhe Multi-Agent Robot Architecture (KAMARA)

The main advantage of distributed controlled robots and subsystems is the decentralized task execution by the system components. In this way, properties for the design of flexible control architectures like modularity, fault-tolerance, integrability and extendibility are easily obtained; furthermore, it is possible to use the concepts of distributed knowledge and decentralized world representation. On the other hand, coordination between the components, e.g. path planning for collision avoidance between both manipulators in a two-arm system, is very difficult to guarantee. To explain these concepts, the Karlsruhe Autonomous Mobile Robot (KAMRO), which is being developed at our institute, is considered. The robot system consists of several subcomponents like two manipulators, hand-eye cameras, one overhead camera and a mobile platform. Extensions to the distributed control architecture KAMARA (KArlsruhe Multi-Agent Robot Architecture) are described that are used to overcome coordination problems, e.g. as caused by the independent task execution of both manipulator systems. Furthermore, we explain in which way the decentralized world representation can be used for parallel task execution. The intelligent control architecture described is used to replace the former control architecture of the autonomous robot KAMRO. The advantages of distributed control systems will be summarized through the actual implementation of the architecture to the robot KAMRO.

Adaptive Problem-solving for Large-scale Scheduling Problems: A Case Study

Although most scheduling problems are NP-hard, domain specific techniques perform well in practice but are quite expensive to construct. In adaptive problem-solving solving, domain specific knowledge is acquired automatically for a general problem solver with a flexible control architecture. In this approach, a learning system explores a space of possible heuristic methods for one well-suited to the eccentricities of the given domain and problem distribution. In this article, we discuss an application of the approach to scheduling satellite communications. Using problem distributions based on actual mission requirements, our approach identifies strategies that not only decrease the amount of CPU time required to produce schedules, but also increase the percentage of problems that are solvable within computational resource limitations.

Innovations in text interpretation

The field of natural language processing is developing a new concentration on interpreting extended texts, with applications in information retrieval, text categorization, and data extraction. The research that addresses these problems represents the first real task-driven focus since machine translation research in the 1960s. Text interpretation applications have already produced good results in accuracy and throughput. This new focus on task-driven text interpretation has been the driving force for a number of advances in the field, because earlier systems fell so far short of the coverage required to interpret bodies of text. The innovations behind this scale-up include work in lexicon development and representation, weak methods of corpus analysis and text pre-processing, and flexible control architectures for parsing. Together, these methods provide coverage and accuracy in interpretation by extending the knowledge that a system can use and controlling how this knowledge is applied. This paper explains the context in which this research is conducted, along with the general progress of the field and some of the details of how our own system realizes these advances.