When a spacecraft lands, a large shock load can lead to undesirable responses such as rebound and tripping. The authors previously discussed the problem of controlling these shock responses using momentum exchange impact dampers. An active/passive hybrid momentum exchange impact damper, which included an active actuator, was proposed. The momentum exchange impact dampers' performances are evaluated by the maximum rebound height, which is proportional to the mechanical energy of the spacecraft. However, the time responses of the energies have not been explained. In addition, the effectiveness of momentum exchange impact dampers was evaluated only in a onedimensional motion simulation. This paper includes theoretical analyses, simulation studies, and experiments. The time responses of the energies of momentum exchange impact dampers are discussed. This paper proposes a robust landing gear system for spacecraft using a hybrid momentum exchange impact damper and evaluates its robustness against ground stiffness variation. First, momentum exchange impact dampers are applied to a mass-damper-spring model, which takes the ground viscosity into account. Next, the proposed model's effectiveness is verified by simulation studies and some experimental results. Finally, this paper studies two-dimensional motion analyses to address rotational motion.
When a spacecraft lands, the large shock load can lead to undesirable responses, such as rebound and trip. The authors have previously discussed the problem of controlling these shock responses using momentum exchange impact dampers (MEIDs). However, the optimal design parameters of MEIDs for spacecraft landing have not yet been addressed. These parameters are crucial for MEID applications. This paper discusses the parameters of Passive-MEID (PMEID) for a single-axis falling-type problem, which is the most fundamental problem. It is found that the rebound height is proportional to the mechanical energy of the spacecraft. Thus, the optimal design parameters of the PMEID correspond to the parameters that minimize the mechanical energy. A PMEID with the optimal design parameters is called optimal PMEID in this paper. In order to improve the performance of the optimal PMEID, this paper proposes a novel MEID -HMEID (active/passive-hybrid-MEID). The HMEID combines actuators with passive elements such as contact springs. Based on the optimal design results for the MEIDs, this paper applies a stiffness control to the HMEID in order to suppress the mechanical energy further. Simulation studies reveal that the HMEID can effectively reduce the influence of shock responses. The robustness of the HMEID against the landing ground is shown. The feasibility of the HMEID is also discussed. The HMEID is superior to a PMEID, even if the actuator has a dynamics with a large electric time constant.
This paper discusses landing response control methods of planetary exploration spacecrafts on the basis of momentum exchange principles. Concretely, the methods adopt momentum exchange impact dampers (MEIDs) that absorb the controlled object's momentum with extra masses close to the object (damper masses). For example, this paper shows
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