Robert E. Reid

The use of wave filter design in Kalman filter state estimation of the automatic steering problem of a tanker in a seaway

The problem of automatic steering control of a large tanker in a seaway is formulated within the framework of linear quadratic Gaussian (LQG) control theory. Wave disturbances are characterized by shaping filters, and Kalman filters are designed using these disturbance noise models. LQG controllers are designed to minimize a performance criterion commonly thought to be representative of propulsion losses due to steering. Performance of the controllers is determined by simulation results, which apply for deep water and are based on data from scale model tests.

MODELING AND IDENTIFICATION OF A LIGHT TRUCK ENGINE MOUNTING SYSTEM FOR RIDE QUALITY OPTIMIZATION

The need for a method to design optimal engine mounting systems is the motivation for the work described in this paper. The paper discusses several vehicle ride quality criteria and the advantages and disadvantages of different performance measures. The problem of vehicle modeling and ride quality optimization through engine mount design is formulated within the framework of linear Quadratic Gaussian (LQG) control theory using an Extended Kalman Filter (EKF) to identify vehicle parameters and to estimate the states. This estimation identification technique is demonstrated using a simple model. A 16 Degree-of-Freedom (DOF) lumped mass vehicle model is described, characterizing the natural frequencies of the engine, cab, and the frame, to be used as a baseline model in describing the vehicle motion.

An optimal controller arising from minimization of a quadratic performance criterion of indefinite form

The problem of minimizing energy loss in automatic steering of ships is considered. Two ship types are analyzed-a high-speed containership and a large oil tanker. Making use of the sufficiency conditions for existence of a stable closed-loop system, it is shown that there is no theoretical difficulty in using an exact performance criterion for energy losses due to steering with an indefinite form, rather than an approximate criterion which fits the positive semidefiniteness condition of standard linear regulator (LR) theory.

Improved LQG Steering Control of a Containership through Application of Full-Loop Transfer Recovery

This paper presents results in the application of recent developments in multivariable control theory to the problem of steering regulator design for open-seas coursekeeping of a containership. Specifically, a need for improved LQG stability margins is demonstrated, and application of Doyle and Steins full-loop transfer recovery procedure is shown to provide improved stability margins without significant loss of propulsive efficiency.

Adaptive Controller to Minimize Ship Steering Propulsion Losses: Time Series Modeling and Statistical Analysis Results

Abstract Statistical time-series and multivariable regression analysis techniques are employed to investigate the properties of a multivariable model for ship/steering and seaway disturbance dynamics. Confidence intervals for the model parameter values to be identified by least-squares in an adaptive steering autopilot scheme are calculated. Residual analysis techniques are used to verify the validity of models via data from ship/steering/seaway simulations. The sufficiency of a firstorder multivariable time-series model within a self-tuning adaptive control algorithm framework is shown to be justified by the results obtained.

Optimal adaptive filtering using finite banks of Kalman filters applied to automatic steering of ships

The problem of minimizing energy loss in adaptive automatic steering of ships is considered. The paper presents the method chosen for the adaptive state estimation phase of the overall control problem. A maximum likelihood technique is employed for adaptively selecting the best Kalman filter from a bank of filters to estimate the ship/steering and seaway model states. The bank consists of previously designed and tested filters for different seaway conditions. The use of this methodology enables the state and parameter estimation problems to be treated separately. The overall adaptive algorithm is structurally simpler than an algorithm which performs these tasks in a combined manner, such as in extended Kalman filtering. With this approach no problem of filter divergence can occur, which is a factor that improves the overall reliability of the autopilot design. Results of simulation studies presented show that the method works very efficiently in selecting the filter gains for the controller to achieve the best performance with respect to minimization of steering related propulsion losses under different seaway conditions.

Analysis of limit cycle behavior using a modified Tsypkin method

The application of a modification of Tsypkins method is demonstrated in the analysis of limit cycle behavior of a certain class of systems for which the Sinusoidal Describing Function method of analysis is not valid. A set of modified periodicity conditions is shown to be necessary, and is derived for the class of systems of interest.

Pseudo-Quickening: A New Display Technique for the Control of Higher Order Systems

The concept of the pseudo-quickened display is introduced as a technique for aiding the control of higher order systems. In this display the intensity of the cursor is employed as a cue for optimal switching of manual control input. Performance on this display is compared with performance on an unaided, a quickened, and a phase plane display. Some advantages over the conventional display in performance are demonstrated by all three aided displays. When all aided groups transferred to an unaided conventional display, only those trained with the pseudo-quickened display showed benefits of prior training. This group also performed better than those who trained only with the conventional display.

Design of the steering controller of a supertanker using linear quadratic control theory: A feasibility study

Linear quadratic (LQ) optimal control theory is applied to the design of the steering controller of a supertanker. A form of performance criterion commonly thought to be representative of propulsion losses related to steering is used as a basis for the design of controllers for course-keeping in the open-seas, for the ship in the full-load and ballast conditions at normal operating speed. The dynamics of the system are based on the use of locally linear models of the ship/steering system around an operating condition, deriving from hydrodynamic data from scale model tests. The effect of variation of the relative weightings in the performance criterion on controller performance when subjected to the seaway environment is examined using sensitivity analyses and simulation studies. The results suggest that it is possible to effect substantial propulsion savings without sacrifice in controllability using LQ techniques. It appears that linear regulator design offers a strong option to existing autopilots and more recently proposed adaptive control systems for ships of this type.