A bilateral control system for flexible master-slave arms with time-varying delay affected by contact force from an obstacle is considered in this study. The proposed bilateral control system is constructed using a rigid master arm, a flexible slave arm actuated by a high-geared servomotor, and a communication network that causes the time-varying delay. The flexible slave arm is affected by contact force from the obstacle during motion. PD and PDS controllers are designed for controlling the rigid master and flexible slave arms, respectively. A Lyapunov function is used in order to prove the stability and passivity of the proposed system. Finally, performance of the proposed bilateral control system is verified by numerical simulations.
Due to advances in mission complexity and increased requirements for autonomous control of small satellites, high-level computing performance of on-board computers, as well as the necessary software implementation to maintain essential functionality, is more frequently required for small satellites. To satisfy these requirements, we developed a high-performance and compact on-board computer for micro and nano-satellites using commercial off-the-shelf (COTS) components including a structure to increase the reliability by sharing software to enhance reusability. The capability of small satellites can be dramatically improved by having common standards for high computing performance and a low-cost platform for the on-board computers. Additionally, the mission potential of small satellites can then be expanded. When the same platform is utilized recursively, the reliability of the platform will increase through repeated verification. In this paper, we describe the concept of a high-performance, low-cost on-board computer system using COTS devices, the sharing of software resources, and a practical on-orbit evaluation of the system.
Design methods of asymptotically stable adaptive consensus control of multi-agent systems composed of the first-order and the second-order regression models are presented based on inverse optimal control criterion. The proposed control schemes are derived as solutions of certain H∞ control problems, where estimation errors of tuning parameters are regarded as external disturbances to the process. The resulting control systems are robust to uncertain system parameters and the desirable consensus tracking is achieved asymptotically via adaptation schemes and L2-gain design parameters together with an introduction of a generating model of a leader.
This paper proposes a sliding mode control with an ellipsoidal sliding surface for vehicle distance control. The performance of two different sliding surfaces, namely ones that are ellipsoidal and linear, is evaluated under the same conditions. Each controller, regardless of sliding surface, is designed to achieve a similar level of control performance. It is shown through simulation that the sliding mode control with the ellipsoidal sliding surface proposed by the authors has advantages over conventional sliding mode control with a linear sliding surface, in that it is smoother and has lower energy consumption. Furthermore, a boundary layer width adaptation law is applied to prevent chattering.
The aim of this paper is to give an extension of the paper [T. Matsuda et al. Proc. 33rd IASTED Modelling, Identification and Control, 809-004, 2014], which gives a robust stability condition for a system with disconnected stability regions. The considered system depends on only one uncertain parameter. In this paper, an explicit algorithm to derive the stability ranges for disconnected stability regions is given. We also extend the result to the case that the system depends on multiple uncertain parameters. A numerical example shows that the proposed method can be applied to robust stability analysis of the lateral dynamics of an aircraft even if all the coefficients of the characteristic polynomial vary. The numerical example also shows that the stability ranges derived by the proposed method are larger than those by a former method.