D-SDRE Based Soft-Landing Control of a Lunar Lander with Active Momentum Exchange Impact Dampers

When a lunar lander touches down, a large impact force may have undesirable effects such as rebounding and overturning. To ensure a safe landing, active momentum exchange impact dampers (AMEIDs) are introduced in this work to enable soft-landing control. For the purpose of designing and evaluating different control strategies applied to the AMEIDs, a two-dimensional lunar lander model is derived using Lagrangian mechanics. The model is validated via a free-fall landing experiment. Using the lander dynamical model, we design a suboptimal control law by solving the discrete-time state-dependent Riccati equation (D-SDRE). The landing response of D-SDRE based controller is compared to that of open-loop control and PID control, respectively. The simulation results show that the DSDRE method mitigates the landing instability and reduces the side-slip phenomenon. © 2021 IEEE.