Adaptive Backstepping Attitude Control of a Rigid Body with State Quantization

Author's accepted manuscript© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In this paper, the attitude tracking control problem of a rigid body is investigated where the states are quantized. An adaptive backstepping based control scheme is developed and a new approach to stability analysis is developed by constructing a new compensation scheme for the effects of the vector state quantization. It is shown that all closed-loop signals are ensured uniformly bounded and the tracking errors converge to a compact set containing the origin. Experiments on a 2 degrees-of-freedom helicopter system illustrate the proposed control scheme.acceptedVersio

Control of Spacecraft Formation with Disturbance Rejection and Exponential Gains

We address the problem of state feedback translational motion control of a spacecraft formation through a modified sliding surface controller using variable gains and I^2 action for disturbance rejection. The exponential varying gains ensure faster convergence of the state trajectories during attitude maneuver while keeping the gains small (and the system less stiff) for station keeping. Integral action is introduced for rejection of disturbances with a constant nonzero mean such as aerodynamic drag. A direct consequence is a drop in energy consumption when affected by sensor noise and a decrease in size of the error states residual when operating close to the equilibrium point. A large number of simulation results are presented to show the control performance

Application of unscented Kalman filter for condition monitoring of an organic Rankine cycle turbogenerator

This work relates to a project focusing on energy optimiza-tion on offshore facilities. On oil and gas platforms it is common practice to employ gas turbines for power produc-tion. So as to increase the system performance and reduce emissions, a bottoming cycle unit can be designed with par-ticular emphasis on compactness and reliability. In such con-text, organic Rankine cycle turbogenerators are a promising technology. The implementation of an organic Rankine cy-cle unit is thus considered for the power system of the Drau-gen offshore platform in the northern sea, which is the case study for this project. Considering the plant dynamics, it is of paramount importance to monitor the peak temperatures within the once-through boiler serving the bottoming unit to prevent the decomposition of the working fluid. This paper accordingly aims at applying the unscented Kalman filter to estimate the temperature distribution inside the primary heat exchanger by engaging a detailed and distributed model of the system and available measurements. Simulation results prove the robustness of the unscented Kalman filter with re-spect to process noise, measurement disturbances and initial conditions. 1

Condition monitoring and maintenance for fibre rope moorings in offshore wind

The FIRM project aims to develop innovative mooring systems for floating wind farms based on fibre ropes, including new and more efficient methods for installation, condition monitoring, maintenance, and decommissioning. The project shall deliver designs for three different mooring systems. This document describes the contents of work package H7 in the FIRM project,publishedVersio

Condition Monitoring Technologies for Synthetic Fiber Ropes - a Review

This paper presents a review of different condition monitoring technologies for fiber ropes. Specifically, it presents an overview of the articles and patents on the subject, ranging from the early 70’s up until today with the state of the art. Experimental results are also included and discussed in a conditionmonitoring context,where failuremechanisms and changes in physical parameters give improved insight into the degradation process of fiber ropes. From this review, it is found that automatic width measurement has received surprisingly little attention, and might be a future direction for the development of a continuous condition monitoring system for synthetic fiber ropes

Techniques for Large, Slow Bearing Fault Detection

Large, slow turning bearings remain difficult to analyze for diagnostics and prognostics. This poses a critical problem for high value assets, such as drilling equipment top drives, mining equipment, wind turbine main rotors, and helicopter swash plates. An undetected bearing fault can disrupt service, and cause delays, lost productivity, or accidents. This paper examines a strategy for analysis of large slow bearings to improve the fault detection of condition monitoring systems. This helps reduce operations and maintenance cost associated with these bearing faults. This analysis is primarily concerned with vibration, and is compared to temperature and grease analysis. Data was available from three wind turbines, where one of the turbine was suspected of having a faulted main bearing

Condition Monitoring Technologies for Steel Wire Ropes – A Review

In this research, we review condition-monitoring technologies for offshore steel wire ropes (SWR). Such ropes are used within several offshore applications including cranes for load handling such as subsea construction at depths up to 3-4000 meters, drilling lines, marine riser tensioner lines and anchor lines. For mooring, there is a clear tendency for using fiber ropes. Especially for heavy-lift cranes and subsea deployment, winches with strong ropes of up to 180 mm in diameter may be required, which has a considerable cost per rope, especially for large water depths. Today’s practice is to discard the rope after a predetermined number of uses due to fatigue from bending over sheaves with a large safety factor, especially for systems regulated by active heave compensation (AHC). Other sources of degradation are abrasion, fretting, corrosion and extreme forces, and are typically accelerated due to undersized or poorly maintained sheaves, groove type, lack of lubrication and excessive load. Non-destructive testing techniques for SWR have been developed over a period of 100 years. Most notably are the magnetic leakage techniques (electromagnetic methods), which are widely used within several industries such as mining and construction. The content reviewed in this research is primarily the developments the last five years within the topics of electromagnetic method, acoustic emissions (AE), ultrasound, X- and γ-rays, fiber optics, optical and thermal vision and current signature analysis. Each technique is thoroughly presented and discussed for the application of subsea construction. Assessments include ability to detect localized flaws (i.e. broken wire) both internally and externally, estimated loss of metallic cross sectional area, robustness with respect to the rough offshore environment, ability to evaluate both rope and end fittings, and ability to work during operation

Control of rigid bodies : with applications to leader-follower spacecraft formations

PhD i teknisk kybernetikkPhD in Engineering Cybernetic