For several future imaging spacecraft, vibration isolation and suppression of its optical payloads have become a challenging problem. These spacecraft have increased performance requirements for the payload, resulting in increased fine steering and vibration isolation requirements. The vibration sources on the spacecraft, however, are increased due to the new large flexible structures and addition of rotating devices. One promising way to address both issues is through the Stewart platform. By using a hexapod with six actuated struts, it is possible to achieve both fine pointing and vibration control. Traditional vibration control algorithms rely on the knowledge of the plant and are usually computationally intensive. This paper applies a computationally efficient vibration control to the Stewart hexapod problem. This algorithm does not rely on the knowledge of the plant other than to find the adaptation rate coefficient and performs well on highly non-linear plants. A convergence analysis is presented. Results are shown for a voice-coil actuated hexapod.

No abstract

No abstract

Abstract. This work proposes a method to estimate the probability of meeting functional requirements of complex products. The method uses concepts and techniques from Systems Engineering and from Reliability. Functional interactions represented in the Functional Flow Block Diagrams (FFBD) are translated into a correspondent configuration of the reliability block diagram (RBD), according to the method's conventions. After that, a reliability value is attributed to each component block, and using reliability evaluation methods the probability of meeting a particular functional requirement is estimated. An application example is presented by missile's subsystem.