In the standard teleoperator system, force and velocity signals are communicated between a master robot and a slave robot. It is well-known that the system can become unstable when even a small time delay exists in the communication channel. In this paper, a method based on the H 1-optimal control and-synthesis frameworks is introduced to design a controller for the teleoperator which achieves stability for a prespeci ed time-delay margin while optimizing performance speci cations. A numerical design example is included.

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Background: It has been shown that intense training can significantly improve post-stroke upperlimb functionality. However, opportunities for stroke survivors to practice rehabilitation exercises can be limited because of the finite availability of therapists and equipment. This paper presents a haptic-enabled exercise platform intended to assist therapists and moderate-level stroke survivors perform upper-limb reaching motion therapy. This work extends on existing knowledge by presenting: 1) an anthropometrically-inspired design that maximizes elbow and shoulder range of motions during exercise; 2) an unobtrusive upper body postural sensing system; and 3) a vibratory elbow stimulation device to encourage muscle movement.

This paper presents some experimental results on actuator fault-tolerant control (FTC) for a quadrotor Unmanned Aerial Vehicle (UAV) system. The strategy is based on Model Reference Adaptive Control (MRAC) where three different MRAC techniques are implemented and compared with a Linear Quadratic Regulator (LQR) baseline controller, namely the MIT rule MRAC, the Conventional MRAC (C-MRAC) and the Modified MRAC (M-MRAC). The main advantage of the MRAC strategy is that it does not require an explicit information about the fault location and/or amplitude and thus, a fault detection and diagnosis module is not needed to detect, isolate and identify the occurred faults. The performance of this MRAC-based FTC is tested in the presence of three types of actuator faults: loss of effectiveness in the total thrust, loss of effectiveness in one of the rotors and partial damage of one propeller.