Autonomous driving technology is expected to be applied to various applications with unmanned vehicles (UVs), such as small delivery vehicles for office supplies and smart wheelchairs. UV remote control by a cloud server (CS) would achieve cost-effective applications with a large number of UVs. In general, dead time in real-time feedback control reduces the control accuracy. On remote path tracking control by the CS, UV control accuracy deteriorates due to transmission delay and jitter through the Internet. Digital twin computing (DTC) and jitter buffer are effective to solve this problem. In our previous study, we clarified effectiveness of them in UV remote control by CS. The jitter buffer absorbs the transmission delay jitter of control signals. This is effective to achieve accurate UV remote control. Adaptive buffering time optimization according to real-time transmission characteristics is necessary to achieve more accurate UV control in CS-based remote control system with DTC and jitter buffer. In this study, we proposed a method for the adaptive optimization according to real-time transmission delay characteristics. To quantitatively evaluate the effectiveness of the method, we created a UV remote control simulator of the control system. The results of simulations quantitatively clarify that the adaptive optimization by the proposed method improves the UV control accuracy.

With the rapid deployment of the Internet of Things, where various devices are connected to communication networks, remote driving applications for Unmanned Vehicles (UVs) are attracting attention. In addition to automobiles, autonomous driving technology is expected to be applied to various types of equipment, such as small vehicles equipped with surveillance cameras to monitor building internally and externally, autonomous vehicles that deliver office supplies, and wheelchairs. When a UV is remotely controlled, the control accuracy deteriorates due to transmission delay and jitter. The accuracy must be kept high to realize UV control system by a cloud server. In this study, we investigate the effectiveness of Digital Twin Computing (DTC) for path tracking control of a UV. We show the results of simulations that use transmission delay values measured on the Internet with some cloud servers. Through the results, we quantitatively clarify that application of DTC improves control accuracy on path tracking control. We also clarify that application of jitter buffer, which absorbs the transmission delay fluctuation, can further improve the accuracy.

In this paper, we propose a novel path tracking control algorithm for an underactuated autonomous underwater vehicle (AUV). The underactuated AUV is controlled by the thrust force and the yaw torque: no sway thruster is used. To deal with this underactuated AUV problem in the path tracking, we introduce an approach angle which makes the AUV converge to the reference path. To design the path tracking controller, we obtain the vehicle's error dynamics in the body-fixed frame, and then design the path tracking controller based on the dynamic surface control (DSC) method. The proposed controller only needs the information of the position and the heading angle of the reference path. Some simulation results demonstrate the effectiveness of the proposed controller.

The problem of designing a robust adaptive control for nonlinear systems with uncertain time-varying parameters is addressed. The upper bound of uncertain parameters, considered even in control coefficients, are not required to be known. An adaptive tracking controller is presented and, using the Lyapunov theory, the closed-loop stability and tracking error convergence is shown. In order to improve the performance of the method, a robust mechanism is incorporated into the adaptive controller yielding a robust adaptive algorithm. The proposed controller guarantees the boundedness of all closed-loop signals and robust convergence of tracking error in spite of time-varying parameter uncertainties with unknown bounds. The parametric uncertain systems under consideration describes a wide class of nonlinear circuits and systems. As an application, a novel parametric model is derived for nonlinear Chua's circuit and then, the proposed method is used for its control. The effectiveness of the method is demonstrated by some simulation results.

This paper deals with a design problem of an observer-based robust preview control system for uncertain discrete-time systems. In this approach, we adopt 2-stage design scheme and we derive an observer-based robust controller with integral and preview actions such that a disturbance attenuation level is satisfactorily small for allowable uncertainties.

In this paper, we study the problem of perfect tracking control of nonminimum phase systems in magnetic levitation system. Generally, perfect tracking control schemes cannot be applied to nonminimum phase plants because of unstable pole-zero cancellations. Although the method of state matching using multirate feedforward control to realize perfect tracking control have been proposed, the oscillation restraint and the feasibility in nonminimum phase system cannot be satisfied at same time. We propose a method using the difference of state variables to generate a smooth desired state variable trajectory in the discrete-time systems. The techniques we proposed are applicable to nonminimum phase discrete-time systems and the oscillations between the sampling points are well restrained. We will show that the structure of the proposed perfect tracking controller is very simple and clear. Finally, computer simulations and experiment results based on magnetic levitation apparatus are presented.

The control problem of hybrid systems have received considerable attention. However, because of the existence of constraints and the combinatorial nature of continuous time and discrete event dynamics, the understanding of hybrid systems is rather limited at present. Only optimal control approaches were proposed based on heuristic rules. Few theoretical properties of system can be predicted until now. In this paper, we consider the tracking control problem of hybrid plants represented by MLD model to follow a family of reference signals produced by an external generator. Some new results are presented. The internal model principle of continuous system is extended to hybrid systems so as to solve the problem.

The conventional describing function of Coulo-mb friction is based on the assumption that the reference input is constant. The author proposes the describing function of Coulomb friction for the ramp reference input. The experimental results for the DC servo motor control system with ramp tracking controller are shown.

A new automated main distributing frame (AMDF) system is developed that reduces operating costs in metallic-cable main distributing frames (MDFs) used for communication networks. In this AMDF system, a robot inserts connecting-pins into the crosspoint holes of matrix-boards. This process allows jumpering to be completed within three minutes and the route-setting for line testing within one minute. The AMDF system provides approximately 2,100 office equipment cable-terminals. Parallel installation of several AMDF systems allows larger MDF systems to be constructed. This system reduces costs and achieves high reliability through three new technologies: high-density matrix-board, precision pin-handling, and a highly reliable system control. Test results for a prototype AMDF system confirm their effectiveness.