Parameter estimation of large flexible aerospace structures with application to the control of the Maypole Deployable Reflector

Systems such as the Maypole deployable reflector have a distributed parameter nature. The flexible column and hoop structure and the circular antenna of 30-100 meter diameter which it supports are described by partial, rather than ordinary, differential equations. Progress completed in reduced order modelling andd controller design and digital parameter estimation and control is summarized. Topics covered include depolyment and on-orbit operation; quasi-static (steady state) operation; dynamic distributed parameter system; autoregressive moving average identification; frequency domain procedures; direct or implicit active control; adaptive observers; parameter estimation using a linear reinforcement learning factor; feedback control; and reduced order modeling for nonlinear systems

Stable Direct Adaptive Control of Linear Infinite-dimensional Systems Using a Command Generator Tracker Approach

A command generator tracker approach to model following contol of linear distributed parameter systems (DPS) whose dynamics are described on infinite dimensional Hilbert spaces is presented. This method generates finite dimensional controllers capable of exponentially stable tracking of the reference trajectories when certain ideal trajectories are known to exist for the open loop DPS; we present conditions for the existence of these ideal trajectories. An adaptive version of this type of controller is also presented and shown to achieve (in some cases, asymptotically) stable finite dimensional control of the infinite dimensional DPS

SPS flexible system control assessment analysis

Active control of the Satellite Power System (SPS0, a large mechanically flexible aerospace structure is addressed. The control algorithm is the principle component in the feedback link from sensors to actuators. An analysis of the interaction of the SPS structure and its active control system is presented

Evolving Systems: Adaptive Key Component Control and Inheritance of Passivity and Dissipativity

We propose a new framework called Evolving Systems to describe the self-assembly, or autonomous assembly, of actively controlled dynamical subsystems into an Evolved System with a higher purpose. Autonomous assembly of large, complex flexible structures in space is a target application for Evolving Systems. A critical requirement for autonomous assembling structures is that they remain stable during and after assembly. The fundamental topic of inheritance of stability, dissipativity, and passivity in Evolving Systems is the primary focus of this research. In this paper, we develop an adaptive key component controller to restore stability in Nonlinear Evolving Systems that would otherwise fail to inherit the stability traits of their components. We provide sufficient conditions for the use of this novel control method and demonstrate its use on an illustrative example

Assisted Community-Led Systematic Land Tenure Regularization

Systematic land cadastre is still an expensive and time-consuming endeavour in Mozambique. Government adopted the approach of systematic land cadastre, launching the "Terra Segura" Programme, to cover 4 thousand communities and 5 million rural parcels, out of an estimated total universe of circa 12 million parcels and plots. The initial exercises to attend this massive registration utilized traditional methods of land tenure regularization, resulting in being either too expensive or time-consuming initiatives, with serious problems of data quality. New approaches were designed and tested to create an effective sustainable cadastre, proposing an holistic approach to register the land. However, because strong evidence must be presented with regards to this holistic approach, there is a need to scale up the tests. The end goal of this scaling up exercise is to learn and disseminate lessons in local capacity development and improve the methodology and tools of the Terra Segura programme. Key Words

Integrating Systems Health Management with Adaptive Controls for a Utility-Scale Wind Turbine

Increasing turbine up-time and reducing maintenance costs are key technology drivers for wind turbine operators. Components within wind turbines are subject to considerable stresses due to unpredictable environmental conditions resulting from rapidly changing local dynamics. Systems health management has the aim to assess the state-of-health of components within a wind turbine, to estimate remaining life, and to aid in autonomous decision-making to minimize damage. Advanced adaptive controls can provide the mechanism to enable optimized operations that also provide the enabling technology for Systems Health Management goals. The work reported herein explores the integration of condition monitoring of wind turbine blades with contingency management and adaptive controls. Results are demonstrated using a high fidelity simulator of a utility-scale wind turbine

Implementation Strategy for Land Administration in Mozambique

Land administration inMozambique needs to become less bureaucratic, simpler, cheaper and more transparent. Design and implementation of traditional approaches is so time consuming that land laws are to be adapted to provide for simpler procedures. Delivery of results (maps, DUATs, spatial plans) requires unconventional approaches, both conceptual and technological. This paper proposes an implementation mechanism for the Land Sector Strategic Plan in Mozambique. A clear priority is identified in this proposal: DUAT production for 5 million parcels before 2025 combined with an land administration organisation where maintenance can be performed. This allows for the future development and introduction of a more comprehensive land governance in the related areas. Land administration is considered as a business that operates within legal frameworks. Topographic mapping and land use planning should be included in this business approach. It is considered that the implementation of the Land Sector Strategic Plan of Mozambique can be achieved by one unique, single organisation for land administration and topographic mapping operating at different levels of administration

Computation with Polynomial Equations and Inequalities arising in Combinatorial Optimization

The purpose of this note is to survey a methodology to solve systems of polynomial equations and inequalities. The techniques we discuss use the algebra of multivariate polynomials with coefficients over a field to create large-scale linear algebra or semidefinite programming relaxations of many kinds of feasibility or optimization questions. We are particularly interested in problems arising in combinatorial optimization.Comment: 28 pages, survey pape

Approximate Deadline-Scheduling with Precedence Constraints

We consider the classic problem of scheduling a set of n jobs non-preemptively on a single machine. Each job j has non-negative processing time, weight, and deadline, and a feasible schedule needs to be consistent with chain-like precedence constraints. The goal is to compute a feasible schedule that minimizes the sum of penalties of late jobs. Lenstra and Rinnoy Kan [Annals of Disc. Math., 1977] in their seminal work introduced this problem and showed that it is strongly NP-hard, even when all processing times and weights are 1. We study the approximability of the problem and our main result is an O(log k)-approximation algorithm for instances with k distinct job deadlines