Trajectory Generator for Hypersonic Vehicle Based on Flight Dynamics

This article proposes a piece of trajectory generator according to flight dynamics for strapdown inertial navigation system. First, this article uses the launch-centered earth-fixed (LCEF) frame as the reference coordinate system to introduce a high-precision flight dynamics model with six degrees of freedom. The trajectory generator proposed in this paper can output specific force, angular velocity, vehicle position, speed, attitude, angle of attack and sideslipping from the LCEF frame and local horizontal frame. The relationship between the 6DoF model and the trajectory generator was examined, and the differences were presented in comparison with traditional trajectory generation. The navigation information from the LCEF frame was converted into a local-level (LL) frame, which provided more information for the trajectory generator. Digital simulation demonstrated that total position error was less than 1 m on the generated 1100 s trajectory data. The hardware-in-the-loop (HWIL) simulation results revealed the accuracy in terms of positioning was below 10 m, and meanwhile, the speed precision was below 0.2 m/s. This proposed trajectory generator coordinated the combined systems of flight control system, the SINS, and 6DoF model. This integrated navigation simulation platform of hypersonic vehicle was designed with the input of the model. At the same time, the platform can simulate the pulse output of IMU and obtain the relevant information of satellite positioning.