| The primary function of feed supporting and tracking system for the new generation Large Radio Telescope(LT) is implemented by cabin-cable parallel mechanism. The workspace, singularity and optimization of cable tension of the cabin-cable parallel mechanism play an important role in the systematic accuracy, which are affected by the structure itself. Therefore, it is necessary to optimize the structure. The main research works can be described as follows.1. A nonlinear equilibrium equation of the cabin-cable system is established, based on which, the cables'lengths and forces are calculated out through an optimal strategy on the distribution of the driving forces.2. The key structural parameters are found, which affect the workspace and singularity of the cabin-cable parallel mechanism. Analysis on the constraint of the structural parameters is done. By changing the structural parameters, the cabin-cable parallel mechanism satisfies the required workspace, and eliminates the singularity.3. In order to reduce cable tension difference, optimization design of cable-cabin supporting structure is carried out. The design parameters include the coordinates of the connected points between cables and cabin, the cross sectional area of the cables, the height of the towers and so on. The constraints are equilibrium equation, material intensity and bounds of variables. The objective is to minimize cable tension difference. For the further saving energy, counterweight is added with the distance changed in time from counterweight to the top of cabin in the work space, which can not only assures orientation of cabin , but also reduces cable tension difference further.4. Where is fit for building towers is chosen in the real landform. After that, optimization design of the cable-cabin supporting structure is done with results satisfying the required workspace. The LT5m model is changed after the optimization of it, which further confirms the validity of the optimal results by a lot of experiments.
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