Track line state detection device and roadbed settlement detection method

The invention discloses a track line state detection device and a roadbed settlement detection method. The detection device consists of a GPS (Global Positioning System) receiving module, a strapdown inertial navigation system IMU (Inertial Measurement Unit), a laser range finder and an odometer. The strapdown inertial navigation system obtains the orientation and the horizontal attitude angle of the detection device through navigation calculation, and combined navigation calculation is carried out by using mileage information, GPS information and the strapdown inertial navigation system to obtain the real-time three-dimensional coordinates and the advancing mileage of the inertial reference in the measurement process; the inertial reference position is further optimized by using the inertia, mileage information and RTK multi-information fusion technology, the vertical distance between the strapdown inertial navigation system and the rail web feature point is obtained based on the laser ranging assembly, and