Design of umbrella-like mechanically deployable aerodynamic decelerators on the basis of plane-symmetric 7R linkages

The surging interest in planetary exploration underscores the need for deployable aerodynamic decelerators with a low ballistic coefficient. This study introduces a novel approach to designing and constructing mechanically deployable aerodynamic decelerators (MDADs) that utilize an umbrella-like mechanism and proposes a new mechanism of MDADs through this method. The proposed method utilizes plane-symmetric 7R (R: revolute joint) linkages, and the kinematics of these linkages are systematically analyzed using the product of exponentials method. The 7R linkage kinematics are equated to an equivalent joint, the foundation for constructing umbrella-like deployable mechanisms. Three distinct types of mechanisms are synthesized using this methodology. Subsequently, their kinematics are analyzed based on the equivalent joint, and the configurations are experimentally validated through 3D-printed models and kinematic simulations. Trajectory simulations and structural analyses are conducted to assess the performance of the deployable mechanisms and provide valuable insights into their capabilities. This research contributes to advancing deployable aerodynamic decelerator technology and offers a promising avenue for future planetary entry, descent, and landing applications. (Figure presented.)