It is effective for robust control design to evaluate complementary sensitivity function if the uncertainty of a controlled object is known. The conventional adaptive control with parameter estimation provides satisfactory control performance against parameter variation but it is not sufficiently robust against unstructured uncertainty. In this paper, we propose a combined adaptive control design referring to parameter estimation against parameter variation and complementary sensitivity function against unstructured uncertainty. The proposed method includes initial estimation of uncertainties using plant input and output, and its stability is proved for an overall adaptive system. The advantage of this design is that initial adjustment of parameters in control law needs little tuning. Experiments and simulations for an oil hydraulic system are performed to verify the effectiveness.
Tuning method “K/s” of parameters for PID controller is proposed. The proposed method approximates the relationship between the manipulating variable and the controlled variable with a model by combining the time-delay and the first-order lead-lag based on the observed data under the closed-loop system. Then, the integral time and the derivative time are determined so that the open-loop transfer function comes closer to K/s by using various constants of that model; and the remaining proportional gain is determined so as to allow securing the given gain margin. In this paper, the identification method and the tuning method are described, then its effectiveness is confirmed by simulation.
This paper describes the principle and design to control an automatic guided vehicle without a servomechanism for steering. In the present method, the position, orientation and steering angle of the vehicle are fed back into the voltage applied to the steering motor, so that the vehicle can follow straight paths and circular paths. The vehicle does not need to measure the steering angle because it can be estimated by the Kalman filter. An experimental vehicle which measures its own position and orientation making use of fluorescent lamps on the ceiling is designed. Experimental results of the vehicle navigation on the straight paths and circular paths show the validity of the present method.
In this paper, an application of genetic algorithm for on-line tuning of a feedforward controller in nonlinear servo systems is described. The parameters in the feedforward controller are regarded as genes and tuned by a genetic algorithm so that the tracking error converges to zero. To achieve high speed tuning, new genetic operations such as a few individuals, quick estimation, instant selection and intentional mutation are introduced. After the tuning process is completed, the nonlinear characteristic of the plant is linearized and an equivalent dynamic inverse is made in the feedforward path. The experimental results demonstrate the effectiveness of the proposed feedforward controller for improvement of tracking performance of the nonlinear speed servo systems.
One of the essential parameters in signal timing, split is the most important variable, particularly at critical intersections where traffic congestion often occurs. There have been previous methods, in which optimum split is calculated in proportion to the critical traffic index. The problem is that determined split using these methods does not necessarily minimize the total delay time for all approaches of an intersection. In this paper, a new method of determining optimum split which satisfies this condition is proposed. In order to evaluate the validity of this approach, the experiments have been carried out, using a traffic flow simulator which simulates the behavior of each vehicle every second. These simulation experiments proved that the method presented here could decrease the queue length at the intersection, compared to the results using conventional methods which did not that efficiently.
In the No. 2 Steel making plant at Kashima Steel Works, CC-DC (Continuous Casting Direct Charge) process has been adopted to realize the synchronized operation between a caster (3CC) and a hot strip mill. In order to take advantage of this process, the BOF (Basic Oxygen Furnace) operation has been required to hit exact end-point carbon contents and metal bath temperatures, and to shorten the refining time. In addition, steel quality depends largely on the end-point hitting ratio. To meet the requirements, we have developed a new endpoint control system of BOF since the renewal of a process computer in 1992. After the adoption of the new system, the direct tapping ratio is about 70%, which results in the reduction of operational cost and the improvement of productivity.
There are demands for a versatile ship control system. The authors have developed a versatile and high performance system for ships by applying advanced control theories. The basic system utilizes a nonlinear actuator force distribution method. Command generators, determinate and indeterminate disturbance compensators, and a joystick manipulator are added to the system. Various control modes are available such as auto-speed keeping, auto-piloting, auto-position keeping, auto-tracking, and berthing. The ship control system design enables function expansion and broad application.
We describe a new control system which stabilizes a looper angle variation caused by rolling disturbances. After estimating the damping coefficient of looper system, this system determines the PI controller gain based on interpolated controller scheme. Experimental results show the usefulness of the proposed method
Skin pass mill is the equipment for the thermal-refing metal rolling of stainless plants, etc. Usually, rolling mill is elastically coupled with the motor driving a rolling mill. Shaft torsional vibration is often generated, when we attempt to get the high control performance of the rolling mill. Such a vibration causes degradation of product quality. In this paper, we propose a method of suppressing the vibrations of steel plate tension using Observer. This method has the excellent characteristic that the vibration-suppressive system is easily constructed just by adding the observer to the conventional control system. This is detailed hereunder.