A segmented attitude planning and controlling method for agile satellite based on Pseudospectral method

To fulfil the high precision requirements of the manoeuvre imaging mode of an agile satellite and solve the shortcomings of existing methods, a segmented attitude planning method based on the Pseudospectral method is proposed. First, a state equation was built by integrating the attitude constraint, time window and other restrictions. Furthermore, to guarantee the accuracy and stability of objects, a segmented strategy of an attitude trajectory approaching the imaging target using a constant angular velocity was proposed. The segmented time, three-axis position and velocity were also determined. Second, taking the global performance into account, the first section of the attitude trajectory was planned by the Legendre Pseudospectral method in order to acquire the optimal state variables and control variables. The second section of the attitude trajectory was then obtained by the constant angular velocity planning method. Next, in order to track the planning trajectory efficiently, a PD controller was designed that was suitable for a segmented planning method. High precision control parameters were obtained by the optimized method. Finally, numerical simulation results show that the proposed segmented attitude planning method successfully meets the high precision requirements of the manoeuvre imaging mode, and the feasibility and effectiveness of this method is verified.