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In future surveys, planetary exploration spacecraft will need to land on rock beds and slopes. Therefore, spacecraft should be equipped with landing methods to facilitate soft landings in these severe regions. However, conventional landing methods have problems such as high rebound, the impossibility of reuse, and excessive resource consumption. To overcome these problems, the authors previously invented several landing methods, but these have practical limitations. Thus, this paper proposes a novel landing mechanism called the base-extension separation mechanism (BESM), which focuses on energy conversion using springs and separable units, and discusses a single-axis falling-type small-scale model of a spacecraft with the BESM. Then, the rebound and acceleration suppression performance is evaluated through simulations. These reveal that the BESM realizes good performance under nominal conditions. The BESM is shown to have good robustness against variations in the ground stiffness, ground damping, spacecraft mass, and installed mass. The study findings reveal that the BESM is a promising method: it overcomes the drawbacks of the conventional methods and our previous inventions. In addition, the BESM generally performs better in soft landings than our previous inventions.

This paper proposes a method to prevent overshoot and undershoot (OS/US) problems for final-state control (FSC) and updating final-state control (UFSC). The FSC is an optimal feedforward control technique to drive a dynamic system to a specified state in a specific time period by an external input. The UFSC is a version of FSC that is modified to deal with a varying final state by updating the FSC control input at each sample. However, both FSC and UFSC algorithms do not guarantee that no overshoot or undershoot occurs in the transient state between the initial state and the final state. This paper proposes an OS/US prevention technique via tuning the FSC or UFSC activated time. The technique is developed by adding a constraint that all the FSC or UFSC control input should be in the same direction. In this paper, the effectiveness of the algorithm is verified by simulations for a plural-cart connection problem.

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