An increasing attention has been attracted toward the development of ROV (remotely operated vehicle) systems for the purpose of investigation and operation in the ocean. It is necessary for ROV to have high maneuvering performance for these purposes. Then, it is important to construct the control system of ROV especially at low speed cruising. The authors constructed a model of low speed cruisung ROV for control law design, because there has been, as yet, no establishment for such a model. Utilizing the model, the optimal robust control theory was applied to improve the characteristics of ROV system. Basic methods for modeling the vehicle and for designing the control system were constructed. The effectiveness of these methods was confirmed.
This paper consider a modeling method for the chemical plant which produces soda and chloride by electrolysis of salt water. A mathematical model for a chloride gas generation plant is built on ARX (Auto-Regressive Exogenous) model where the input and output are opening rate of the control valves and the pressure of chlorine gas in the reaction tank, respectively. Using real measurement data for the chemical plant, the ARX model is constructed where the best order of the model is determined by AIC criterion. Finally, the simulation results are illustrated to show qualitatively the effectiveness of the mathematical model used here for the pressure of chlorine gas.
A mathematical model of a phenol polymerization process in the batch reactor is derived by considering reaction rate, mass and energy balances. Kinetic reaction parameters are estimated from experimental data and parameters of energy balances are obtained from reactor operating conditions. Simulating the process responses by using various system parameters, it is confirmed that this model well explains the real process. Then, the gain scheduling control is applied. It is found from computer simulation that this gain scheduling control system shows excellent dynamic responses than the conventional control system. This study emphasizes that developing a suitable mathematical model is very much important for control system design.
This paper is concerned with two parameter identification methods for inertial parameters of the unknown object handled by manipulators on a free-flying space robot under the condition that the robot is free to translate and rotate. One method is based on the conservation principle of linear and angular momentum, and the other on Newton-Euler equations of motion. Only the linear/angular velocities and accelerations of the satellite are used in the identification methods with no information of the force and torque utilized. The feasibility of the methods is demonstrated by a hardware experiment on the ground as well as numerical simulations.
Wheeled vehicles are known as systems with non-holonomic constraint, and their trajectory can not be easily controlled using ordinary control strategies. In this paper, we will design a path tracking controller for wheeled vehicles using exact linearization technique and time scale transformation which are developed in nonlinear system theory. In the proposed controller design, we will describe the vehicle's behavior with a nonlinear state equation, whose time scale is the distance along the desired path. Then, we will design a stabilizing controller for this nonlinear state equation using exact linearization technique. We will show, in the simulation, the vehicle with the proposed controller tracks the desired straight line as it is moving forward and/or backward. Based on this path tracking controller, we will also propose the path planning method for parking control of vehicles using forward and backward movement.
In the vibration control of flexible structures, the closed-loop system may be unstable by exciting higher modes which are neglected in the design. In this paper, we discuss a design method of robust controller of a flexible bridge based on the normalized left coprime factorization approach. We show that this method is simple and straightforward to reflect the control objectives such as robustness and performance, on the design. And the validity of the controller is confirmed by some experiments. We also show that this controller has the same structure as a full state observer and the selection of observer gain has a very important role in the design of robust controller.
This paper is concerned with robust controller design for a class of nonlinear systems. First, taking account of the nonlinearity of the systems, we propose a controller design method which consists of H∞ robust control and exact linearization via nonlinear state feedback. The latter one is designed to yield the linear system which is exactly equal to the linear approximation model of the plant around an equilibrium point. Second, applying the proposed method to a simple magnetic levitation system, we illustrate the validity of our method by experiments.
In this paper, we present two design schemes of continuous-time model reference adaptive control system (MRACS) which are robust to modeling error of a plant. At first, we present a design scheme of MRACS in which we utilize a design approach of variable structure systems (VSS). In this design scheme, we can ensure robustness property of MRACS in the presence of modelling error by choosing appropriate parameters which are decided by the designer and make the output-error between the plant and the reference model asymptotically zero. However, it is possible that the use of VSS design approach causes chattering phenomena in this design scheme. To overcome this drawback, we also propose another design scheme in which we consider the prevention of chattering phenomena.