Optimal Output Regulation for Square, Over-Actuated and Under-Actuated Linear Systems

This paper considers two different problems in trajectory tracking control for linear systems. First, if the control is not unique which is most input energy efficient. Second, if exact tracking is infeasible which control performs most accurately. These are typical challenges for over-actuated systems and for under-actuated systems, respectively. We formulate both goals as optimal output regulation problems. Then we contribute two new sets of regulator equations to output regulation theory that provide the desired solutions. A thorough study indicates solvability and uniqueness under weak assumptions. E.g., we can always determine the solution of the classical regulator equations that is most input energy efficient. This is of great value if there are infinitely many solutions. We derive our results by a linear quadratic tracking approach and establish a useful link to output regulation theory.Comment: 8 pages, 0 figures, final version to appear in IEEE Transactions on Automatic Contro

In search of synergies between policy-based systems management and economic models for autonomic computing

Policy-based systems management (PBM) and economics-based systems management (EBM) are two of the many techniques available for implementing autonomic systems, each having specific benefits and limitations, and thus different applicability; choosing the most appropriate technique is the first of many challenges faced by the developer. This talk begins with a critical discussion of the general design goals of autonomic systems and the main issues involved with their development and deployment. The discussion forms a backdrop for a detailed evaluation of the two techniques, in which the concepts underpinning each of PBM and EBM are reviewed and placed into context with each other as well as with the other popular techniques for autonomic computing. After considering the operation and suitability of the techniques in isolation, the focus shifts to look at how PBM and EBM could be combined in complementary ways to achieve more sophisticated and versatile control systems whilst keeping the complexity and human-configuration input low. There is then some deeper explanation of the features of PBM and a specific technology is briefly presented as a case example, focusing on its novel and advanced features. The talk ends by looking to the future of autonomic systems; identifying a possible next set of challenges and considering the roles that PBM and EBM may play in addressing these

Time-varying partitioning for predictive control design: density-games approach

The design of distributed optimization-based controllers for large-scale systems (LSSs) implies every time new challenges. The fact that LSSs are generally located throughout large geographical areas makes dicult the recollection of measurements and their transmission. In this regard, the communication network that is required for a centralized control approach might have high associated economic costs. Furthermore, the computation of a large amount of data implies a high computational burden to manage, process and use them in order to make decisions over the system operation. A plausible solution to mitigate the aforementioned issues associated with the control of LSSs consists in dividing this type of systems into smaller sub-systems able to be handled by independent local controllers. This paper studies two fundamental components of the design of distributed optimization-based controllers for LSSs, i.e., the system partitioning and distributed optimization algorithms. The design of distributed model predictive control (DMPC) strategies with a system partitioning and by using density-dependent population games (DDPG) is presented.Peer ReviewedPostprint (author's final draft

Distributed State Machine Supervision for Long-baseline Gravitational-wave Detectors

The Laser Interferometer Gravitational-wave Observatory (LIGO) consists of two identical yet independent, widely-separated, long-baseline gravitational-wave detectors. Each Advanced LIGO detector consists of complex optical-mechanical systems isolated from the ground by multiple layers of active seismic isolation, all controlled by hundreds of fast, digital, feedback control systems. This article describes a novel state machine-based automation platform developed to handle the automation and supervisory control challenges of these detectors. The platform, called \textit{Guardian}, consists of distributed, independent, state machine automaton nodes organized hierarchically for full detector control. User code is written in standard Python and the platform is designed to facilitate the fast-paced development process associated with commissioning the complicated Advanced LIGO instruments. While developed specifically for the Advanced LIGO detectors, Guardian is a generic state machine automation platform that is useful for experimental control at all levels, from simple table-top setups to large-scale multi-million dollar facilities.Comment: Version 2: 11 pages, 9 figures. Submitted to Review of Scientific Instrument

Autonomy Infused Teleoperation with Application to BCI Manipulation

Robot teleoperation systems face a common set of challenges including latency, low-dimensional user commands, and asymmetric control inputs. User control with Brain-Computer Interfaces (BCIs) exacerbates these problems through especially noisy and erratic low-dimensional motion commands due to the difficulty in decoding neural activity. We introduce a general framework to address these challenges through a combination of computer vision, user intent inference, and arbitration between the human input and autonomous control schemes. Adjustable levels of assistance allow the system to balance the operator's capabilities and feelings of comfort and control while compensating for a task's difficulty. We present experimental results demonstrating significant performance improvement using the shared-control assistance framework on adapted rehabilitation benchmarks with two subjects implanted with intracortical brain-computer interfaces controlling a seven degree-of-freedom robotic manipulator as a prosthetic. Our results further indicate that shared assistance mitigates perceived user difficulty and even enables successful performance on previously infeasible tasks. We showcase the extensibility of our architecture with applications to quality-of-life tasks such as opening a door, pouring liquids from containers, and manipulation with novel objects in densely cluttered environments

The European Regulatory Framework and its implementation in influencing organic inspection and certification systems in the EU

The report presents a review of the most important European and international legislation that set the framework for organic certification, of reports prepared by international agencies working with organic standard setting and certification, and of relevant scientific literature. It discusses problems, future challenges of the organic control systems in Europe leading to suggestions for improvement. Food quality assurance is of key importance for the future development of the Common Agricultural Policy of the EU. A large number of mandatory and voluntary assurance and certification schemes exist for agriculture and in the food industry leading to the risk of increased costs for producers and confusion of consumers. Such schemes include the setting of requirements and bodies that undertake control and provide certificates. Requirements can be divided into statutory regulations regarding food safety and good agricultural practice and standards for voluntary attributes. Basic requirements of food safety, animal health and animal welfare are controlled by the Official Food and Feed Control (OFFC) systems, governed by Council Regulation (EC) 882/2004. Third party certification provides credibility to claims related to voluntary standards and is communicated to the consumers through the use of certification marks. The EU has developed a legislative basis for quality claims in relation to geographical indications, traditional specialities and organic farming and considers introducing labelling rules in relation to animal welfare, environmental impact and the origin of raw materials. Organic certification is one of a number of overlapping and competing schemes. The development of organic standards and certification in Europe started with private standards and national rules, leading to Regulation (EEC) 2092/1991. The requirements for competent authorities, control bodies and operators in this regulation regarding the control systems are reviewed. The discussion highlights the low level of knowledge among consumers of the requirements of organic certification, a weak emphasis of the control system on operator responsibility for organic integrity, issues of competition and surveillance of control bodies, a lack of consideration of risk factors in designing the inspection systems and a lack of transparency. A total revision of the European Regulations on organic production began in 2005. One important change introduced by the new Council Regulation (EC) 834/2007 for Organic Food and Farming is that the organic control system is placed under the umbrella of Council Regulation (EC) 882/2004 on Official Food and Feed Controls. Regulation (EC) 834/2007 also requires that control bodies have to be accredited according to general requirements for bodies operating product certification systems (ISO Guide 65/EN 45011). From July 2010 packaged organic products will have to carry the new EU logo as well as the compulsory indication of the control body. The report reviews the requirements for competent authorities, control bodies and operators from the various legal sources. The discussion highlights a lack of clarity on the impact of the OFFC regulation on the organic control system including how risk based inspections are to be implemented and the potential for in-consistencies in the enforcement of the regulation. A number of international initiatives concerned with the harmonisation of organic standards and to a lesser extent certification are reviewed, such as the International Task Force on Harmonisation and Equivalence (ITF)1 Two main alternative guarantee systems for organic production have been developed and researched by a number of organisations including IFOAM, ISEAL, FAO and the EU Commission. Smallholder Group Certification based on an Internal Control System (ICS) and Participatory Guarantee Systems (PGS) could also represent ways to minimize certification costs also for European farmers, in particular for operators that market directly or through very short supply chains. Both systems also illustrate examples of certification systems with a focus on system development and improvement. , the European Organic Certifiers Council (EOOC), the International Social and Environmental Accreditation and Labelling Alliance (ISEAL) and the Anti-Fraud Initiative (AFI). The multilateral initiatives have led to a better understanding of current problems and the scope and limitations for harmonisation. They have also contributed to the sharing of tools and methods and the identification of best practice. Apart from organic farming the European Union has two other food quality schemes: Regulation (EC) 510/2006 on geographical indications and Regulation (EC) 509/2006 on traditional specialities. The report explores the potential for combining these with organic certification, and draws lessons for organic certification based on Italian experience. The final chapter summarises problems and challenges from the previous chapters. Suggestions for improvements of the organic control system focus on two issues: the need for further harmonisation of the surveillance of control bodies and enforcement of the regulation and how operators’ responsibility for further development of organic systems could be supported in the control and certification system

Legislative History of the Fair Labor Standards Act

With recent advances in power electronic technology, High-Voltage Direct Current (HVDC) transmission system has become an alternative for transmitting power especially over long distances. Multi-Terminal HVDC (MTDC) systems are proposed as HVDC systems with more than two terminals. These systems can be geographically wide. While in AC grids, frequency is a global variable, in MTDC systems, DC voltage can be considered as its dual. However, unlike frequency, DC voltage can not be equal across the MTDC system. Control of DC voltage in MTDC systems is one of the important challenges in MTDC systems. Since the dynamic of MTDC system is very fast, DC voltage control methods cannot rely only on remote information. Therefore, they can work based on either local information or a combination of local and remote information. In this thesis, first, the MTDC system is modeled. One of the models presented in this thesis considers only the DC grid, and effects of the AC grids are modeled with DC current sources, while in the other one, the connections of the DC grid to the AC grids are also considered. Next, the proposed methods in the literature for controlling the DC voltage are described and in addition to these methods, some control methods are proposed to control the DC voltage in MTDC system. These control methods include two groups. The first group (such as Multi-Agent Control methods) uses remote and local information, while the second group (such as Sliding Mode Control and H¥ control) uses local information.The proposed multi-agent control uses local information for immediate response, while uses remote information for a better fast response. Application of Multi-Agent Control systems leads to equal deviation of DC voltages from their reference values. Using remote information leads to better results comparing to the case only local information is used. Moreover, the proposed methods can also work in the absence of remote information. When AC grid is considered in the modeling, the MTDC system has anon-linear dynamic. Sliding Mode Control, a non-linear control method with high disturbance rejection capability, which is non-sensitive to the parameter variations, is applied to the MTDC system. It controls the DC voltage very fast and with small or without overshoot. Afterward, a static state feedback H¥ control is applied to the system which minimizes the voltage deviation after a disturbance and keeps the injected power of the terminals within the limits. Finally, some case studies are presented and the effectiveness of the proposed methods are shown. All simulations have been done in MATLAB and SIMULINK.QC 20140911</p