Model Analysis And Experimental Research On The Feed Tracking System Of Large Radio Telescope

Based on the nonlinear equilibrium equation of the cable-cabin system, a stationary model for position control of the flexible cable-cabin system with large span is established through optimal strategy on the distribution of the driving forces. Thus the unlooped control of movement of the cabin is realized by adjusting the lengths of the cables coordinately.The singularity curves are founded on the working surface of the feed. Further two schemes to eliminate the singularity are proposed. One of the schemes improves the distribution of the connecting points among the cabin and cables and the other increases redundant cables. By these ways a smooth movement of the cabin is ensured. A systemic analyzing method and the special simulating software for wind-induced vibration of the cable-cabin structure are programmed. By which the controllable precision on the cabin with the cables is estimated under wind disturbing. The estimation is valuable to the allotment on the precisions between the two control subsystems for the feed tracking. Furthermore the possibility of vortex-induced resonance of the cable-cabin structure is estimated too.Several errors of the model of the cable-cabin mechanism for unlooped control are founded and eliminated through a lot of optomechatronics experiments. Further some unlooped experiments are made. Besides the simulating on wind-induced vibration and vortex-induced vibration of the cable-cabin structure are all validated.Based on Newton-Euler method a dynamic model for Stewart platform control is constituted which involves the inertias of the platform and six legs and frictions at joints. Through the model the inverse dynamic problem of Stewart platform is solved and a foundation is made for Stewart platform control used for 500m LT. Meanwhile all the restrained forces acted at joints are found which provide analysis condition for the mechanism design. A simplified resultant force acted on the cabin by Stewart platform is given which makes it possible to eliminate the dynamic coupling between the two subsystems by means of active vibration control.According to the structures of Jacobian matrixes of kinematics, statics and dynamics, the relationships among kinematic singularity, static singularity and dynamic singularity are explored on the parallel manipulators similar with Stewart platform. It is found that the three kinds of singularities occur simultaneously.