Ikuro Mizumoto

Simplified adaptive model output following control for plants with unmodelled dynamics

In this paper, an adaptive model output following control utilizing almost strictly positive real (ASPR) characteristics of the plant is considered. The plant is said to be ASPR if there exists a static output feedback such that the resulting closed-loop transfer function is strictly positive real. A design scheme of an adaptive model output following control system having a simple structure is proposed for the ASPR plant. The ASPR condition imposes severe restrictions on the plant with relation to the practical application. However, we can construct an ASPR augmented plant, which is regarded as a virtually new controlled plant, by implementing a parallel feedforward compensator or pre-compensator on the plant. The design scheme of such compensators that make the non-ASPR plant virtually ASPR is proposed by taking plant uncertainties into consideration. As a result, the applicable class of the proposal can be expanded. The effectiveness of the proposed methods is confirmed through numerical simulations.

Brief paper: Adaptive output feedback control of general MIMO systems using multirate sampling and its application to a cart-crane system

In adaptive output feedback control based on almost strictly positive real conditions, a technical difficulty arises when the multi-input multi-output (MIMO) system under consideration is non-square, and in particular, has less inputs than outputs. To overcome this, we propose the idea of multirate sampled-data control-by carefully choosing faster input sampling rates, we obtain a lifted discrete-time system, which has the same number of inputs and outputs and does not give rise to the causality constraint. The adaptive control strategy is then applied to the lifted system, resulting in a multirate adaptive output feedback controller which is implementable digitally and provides closed-loop stability under certain conditions. The results reported here are validated on an experimental cart-crane system.

CONTROLLED SYNCHRONIZATION OF TWO 1-DOF COUPLED OSCILLATORS

Two 1-DOF pendulums coupled with a weak spring are considered. This system is a coupled Controlled Hamiltonian Systems that has been studied widely in these days. The control objective is to make pendulums swing synchronously with small input. To this end, Speed Gradient Energy method proposed by Fradkov is adopted to design the controller. Although experimental results showed that the method succeeded in achieving the objective, the mechanism of synchronization was not clear. In this study, the contracted dynamics of the whole system is analyzed and properties of the system are investigated. Through the investigation, a criteria to define the feedback gain of the controller is revealed. Computer simulation and experimental results showed the validity of the method.

Wind Estimation by Unmanned Air Vehicle with Delta Wing

In this paper, an algorithm to estimate wind direction by using a small and light Unmanned Air Vehicle(UAV) called KITEPLANE was proposed. KITEPLANE had a big main wing which is a kite-like delta shape and, therefore, it was easy to be disturbed by wind. However, this disadvantage implies that the KITEPLANE has an ability to sense wind and that it is expected to use the KITEPLANE as a sensor for wind estimation. In order to achieve this feature, dynamics of the KITEPLANE under wind disturbance were derived and a numerical estimation method was proposed. Devices equipped on board were also developed and the proposed method was implemented. Results of an experiment showed the effectiveness of the proposed method.

Simple adaptive control of processes with time-delay

Abstract This paper is concerned with the development of tuning guidelines and robustness evaluation tools for a simple adaptive control (SAC) scheme. The adaptive technique requires knowledge of only the relative degree of the plant and an upperbound of the process gain. This is an explicit or direct adaptive scheme. The SAC method is evaluated by simulated applications to two processes. The application of SAC to a process with time-delay is also considered in this paper. This issue has both theoretical, because of the strictly positive real (SPR) requirements, as well as practical appeal. Simulation results show the practicality and usefulness of the proposed algorithm.

Autopilot System for Kiteplane

This paper proposes an autopilot system for a small and light unmanned air vehicle called Kiteplane. The Kiteplane has a large delta-shaped main wing that is easily disturbed by the wind, which was minimized by utilizing trim flight with drift. The proposed control system for autonomous trajectory following with a wind disturbance included fuzzy logic controllers, a speed controller, a wind disturbance attenuation block, and low-level feedback controllers. The system was implemented onboard the aircraft. Experiments were performed to test the performance of the proposed system and the Kiteplane nearly succeeded in following the desired trajectory, under the wind disturbance. Although the path was not followed perfectly, the airplane was able to traverse the waypoints by utilizing a failsafe waypoint updating rule

Robust adaptive tracking control for time-varying nonlinear systems with higher order relative degree

This paper deals with a controller design problem for time-varying nonlinear systems with nonparametric uncertainties. A robust adaptive tracking control for uncertain time-varying nonlinear systems with higher order relative degree will be proposed based on the high-gain adaptive output feedback and backstepping strategies. The proposed method is useful in the case where only the output signal is available.

Brief paper: Output feedback strict passivity of discrete-time nonlinear systems and adaptive control system design with a PFC

In this paper, a passivity-based adaptive output feedback control for discrete-time nonlinear systems is considered. Output Feedback Strictly Passive (OFSP) conditions in order to design a stable adaptive output control system will be established. Further, a design scheme of a parallel feedforward compensator (PFC), which is introduced in order to realize an OFSP controlled system, will be provided and an adaptive output feedback control system design scheme with a PFC will be proposed.

Robust parallel compensator design for output feedback stabilization of plants with structured uncertainty

Abstract This paper deals with a design problem of robust parallel compensator which guarantees the existence of a constant gain output feedback controller for plants with structured uncertainty. First, robust design conditions of such a compensator are derived by using Kharitonov’s Theorem. Then, based on conditions provided, the parallel compensator is designed by utilizing the maximal range of interval perturbations of the plant. A numerical example is given to demonstrate the validity of the results.

Audio servo for robotic systems with pinnae

Sound localization is one of important abilities for robots which utilize auditory information. Binaural information such as interaural time difference (ITD) or interaural intensity difference(IID) is effective for horizontal sound localization. In order to extend this ability to vertical sound localization, spectral cues were utilized in this paper instead of increasing number of microphones. Spectral cues were the information about the vertical position of the sound source on frequency domain. Since spectral cues strongly depended on the shape of pinnae, artificial pinnae for auditory robots were designed based on diffraction-reflection model. A method to detect spectral cues was also developed. By utilizing them, a controller which made the robot orient to the sound source was proposed. Results of an experiment showed the validity of the proposed method.