Development And Research Of A Biomimetic Sunflower Phototropism Fiber-Optic Daylighting System

Because the resources are shortage,and the environment is seriously polluted,the solar energy has been focused by all countries for its clean and unlimited characteristics.At the present stage,there are mainly two ways to use solar energy:one is the direct use of it,and the other is the indirect use of it.In practical application,the sun tracking mechanism is one of the important factors that affect the daylighting efficiency of the fibre-optic daylighting system.At present,such problems as unnecessary incoupling torque,large tracking error and strict orthogonality between two shafts exsit in two-axis tracking mechanism.In order to overcome the weaknesses of two-axis tracking mechanism,the new mechanism of sunflower phototropism based on bionics principle was proposed.And,a new biomimetic sunflower tracking mechanism was designed.In the new tracking mechanism,sunflower was replaced by sun tracking panels.Cell division and proliferation of plant was instead of rope movement.And the sensitive parts of sunflower was replaced by the four quadrant photoelectric sensor.Eventually,the bionic process of sunflower movement was realized.And the designing of the tracking mechanism of the sunflower phototropism was completed.In order to ensure daylighting efficiency,a closed loop control model was adopted in this new tracking system.Active tracking with passive tracking was used in the control model.And the software of the system was completed under two tracking methods.Because the complicated motion of the bionic sunflower tracking mechanism was similar to the Euler disk,it was difficult to realize the active tracking control of this new tracking mechanism.Therefore,a mathematical model of the bionic sunflower tracking mechanism was constructed.The model was based on the space analytic geometry theory and the sun position algorithm.Then,the inverse position solution of tracking plate of the bionic sunflower tracking mechanism was obtained.And the active control of bionic sunflower tracking mechanism was realized.The passive tracking scheme of tracking system was designed by using photoelectric sensor module.It was used to eliminate the tracking error caused by active tracking.The stability of the bionic sunflower tracking mechanism was the premise of the tracking system to track the sun.By solving and analysing the factor of the stability of the bionic sunflower tracking mechanism in the whole work space,it was proved that the bionic tracking mechanism could operate stably.A mathematical model based on the optimization algorithm theory about azimuth axis deviation of tracking mechanism of bionic sunflower was built.And the tracking error was analyzed,in this paper.The tracking error of bionic sunflower tracking mechanism was much smaller than that of the two axis tracking mechanism,which meant that the bionic sunflower tracking mechanism was more efficient in lighting.Based on the above tracking system,the designing of the light transmission module was completed.And,the construction of the sunlight fiber-optic lighting system was finished.Moreover,the debugging of the outdoor and the testing of lighting system were accomplished.Finally,the tracking of the sun and the indoor lighting function was carried out by the bionic sunflower tracking mechanism.