Disturbance compensated terminal sliding mode control for hypersonic vehicles

An attitude control approach for hypersonic vehicles based on disturbance compensated terminal sliding mode(TSM) was studied. First, a modified TSM surface which switched to high gain linear sliding mode surface while in the neighborhood of equilibrium point was proposed to overcome the singularity problem of traditional TSM, and maintain the high rate of convergence. Then the error convergence property of the proposed TSM in the presence of disturbances was analyzed theoretically. To improve the robustness and precision of TSM control, extended state observer(ESO) was designed to estimate and compensate for disturbances. Finally, 6-degree of freedom numerical simulation was carried out, and the simulation results demonstrate that the control performance and robustness are improved by the proposed method.