A cable-suspended parallel robot utilizes the basic idea of Stewart platform but replaces parallel links with cables and linear actuators with winches. It has many advantages over a conventional crane. The concept of applying a cable-suspended parallel robot into the construction and maintenance of giant telescope is presented in this paper. Compared with the mass and travel of the moving platform of the robot, the mass and deformation of the cables can be disregarded. Based on the premises, the kinematic and dynamic models of the robot are built. Through simulation, the inertia and gravity of moving platform are found to have dominant effect on the dynamic characteristic of the robot, while the dynamics of actuators can be disregarded, so a simplified dynamic model applicable to real-time control is obtained. Moreover, according to control-law partitioning approach and optimization theory, a workspace model-based controller is proposed considering the characteristic that the cables can only pull but not push. The simulation results indicate that the controller possesses good accuracy in pose and speed tracking, and keeps the cables in reliable tension by maintaining the minimum strain above a certain given value, thus ensures smooth motion and accurate localization for moving platform.
"Interaction-free measurements" (IFM) originate from the latest quantum interferometric technologies. The latest research of quantum optics demonstrates, by using the complementary wavelike and particlelike natures of photons, it is possible to make interaction-free measurements by which the presence of an object can be determined with no photons being absorbed. The paper introduces the concept of "Interaction-free Measurement" (IFM), the original Elitzur-Vaidman scheme, the "High Efficiency Interaction-free Measurement", the application of quantum Zeno effect and the improved scheme proposed by Kwiat et al. The EV scheme is implemented in a Mach-Zehnder interferometer. Theoretically this paper also draws a conclusion in IFM feasibility by analyzing the wave functions of photon at various locations in the interferometer.
The next generation of large telescope in China will be 30m class. Based on the studies of LAMOST enclosure, we carry on feasibility studies for CFGT enclosure and conclude that the dimension of enclosure will be in the range of 50-60 m. The design should be featured with optimum dome seeing performance, good wind buffet capability and reasonable cost effectiveness. All the structure frames will be made of compact space trusses, optimized in dimension and minimized in cost. Two preliminary plans for enclosure adopting "open-air" and "foldaway" approach are proposed. The folded enclosure located on a large circular air-cushion can rotate to the wind direction and act as wind screen to mitigate the effects of wind-buffeting on the telescope. A new kind of crane-robot crane will be employed into the service of telescope. The enclosure control system based on Fieldbus network controls and monitors all the devices in the enclosure, including robot crane, driving motors and sensors. The sensors send relevant parameters to computer and the computer controls the corresponding devices to ensure better performance of the enclosure. This paper describes the preliminary design for the CFGT enclosure and discusses the possible technologies to build enclosure.