Design And Research Of A Daylight Tracking Device Driven By SMA

The problem of adaptive lighting at the entrance and exit of the tunnel has always been one of the key and difficult points in tunnel construction and application,and the main reason is that the light inside and outside of the entrance and exit is different.The strong visual difference will cause short-term blindness to the driver,which is very easy to cause traffic accidents.Sunlight lighting is an effective solution.No need for long-distance cables and power supply systems.In addition,it has better synchronization of the light intensity between the entrance and exit of the tunnel and the outside world,and more comfortable visual experience for drivers and passengers.Although solar lighting can solve the problem very well,the lack of a daylight tracking device that fits with it greatly limits the application of solar lighting.For this reason,a new type of daylight tracking device driven by SMA springs was researched and designed,which will greatly help the adaptive lighting of tunnel entrances and exits,and provided another option for the tracking part of small solar equipment.(1)Starting from the movement characteristics of daylight tracking,using sunflower as a reference prototype,a new structure combining rigid motion and flexible motion is designed.The three-dimensional displacement support module breakthrough uses SMA spring as the intelligent driving source.The structure of the flexible rod adopts a cylindrical rod with a hollow diameter of five-sevenths of the total cross-section,and a driving force of8.73 N can be applied to achieve a bending motion of 60.66°.The positioning and clamping module is designed as a structure similar to a magnetic buckle,and the clamping force exceeds 100 N.(2)Through three sets of specific experiments,the constructed SMA spring motion model and the driving stress and strain generated by electric heating are tested and verified;SMA springs with a length of 11 cm or more can generate a driving force greater than27 N.The maximum expansion and contraction amount is 70 mm at a constant load of 25 N,which can meet the requirements of the device for driving displacement.(3)Carrying out the motion simulation of the device show that it takes about 50 s to drive the telescopic drive to the maximum position,the displacement is about 52 mm,the deformation of the flexible rod is 8mm,the maximum inclination of the tracking board reaches 63°,and the maximum tracking time and tracking range meet the design requirements.(4)During the movement,the maximum load of the device is 225 MPa,and the maximum load of the flexible rod is 12 MPa,which are all within the material bearing range,and the device has good safety.The device’s error elimination capability is much higher than the existing tandem dual-axis device,the elevation angle and azimuth angle can be increased by 82.5% and 99.3% respectively,and the designed daylight tracking device is more suitable for solar lighting systems.