As the material undergoes plastic deformation, its yield limit ( x y i e l d) changes. Then, it is further deformed toward point (2), and finally, it is unloaded to (3). The following load cycle is schematized: the untouched crash unit (0) is deformed up to the yield limit (1). Figure 5 highlights the load-deformation characteristic of the crushable absorber unit, which implements the linear elastic, perfectly plastic characteristic under the imposed deformation. To simulate the nonlinear behavior of the crushable absorber, the relative velocity and position between the two beams connected by the prismatic joint are sensed and used as input for an external function modeling both the elastic and dissipative functions, leading to plastic deformation of the honeycomb material. The prismatic joint modeling the crash absorber movement is driven by an external force input moving the mobile beam with respect to the base one. discussed the design of compliant joints for passive self-leveling lunar landing gear. For dealing with leveling systems, Rippere et al. ![]() The six-legged mobile repetitive lander prototype HexaMRL integrates both lander and rover functions by exploiting electromechanical active joints. proposed the design and modeling of a new type of lunar lander gear equipped with a magnetorheological fluid damper for semi-active landing control. The Insight’s Seismic Experiment for Internal Structure of Mars (SEIS) developed a full lander with an actuated and damped cradle subsystem for seismic characterization. They also studied touchdown dynamics and validated the actuator behavior through a prototype. proposed a translation–rotation motion conversion mechanism for a lunar or planetary lander. In more recent efforts, research has explored the use of modern actuators together with more advanced numerical tools to validate them in more realistic working conditions. It is found that the proposed methodology is able to yield a compact, well-sized actuator which is numerically validated with the E元 platform as a case study. To validate the proposed ALS design methodology, a virtual test bench is used to assess the ALS performances under different load scenarios. Then, the electric motor model is numerically validated and optimized through electromagnetic finite element analysis. First, a parametric sensitivity approach is used to optimize the transmission system and the electric machine characteristics. The leg dynamic behavior is simulated through a parameterized multi-body model to investigate different landing scenarios. The actuator aims to both provide proper leg deployment functioning and compensate for the different shock absorber deformations during landing. The proposed ALS actuator is fitted within the leg’s primary strut and features a custom permanent-magnet synchronous machine rigidly coupled with a lead screw. The ALS actuator is integrated into an inverted tripod leg layout, exploiting a honeycomb crushable damper as a shock absorber. ![]() This work proposes a systematic methodology for designing an active leveling system (ALS) actuator for lunar landing application.
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