Dynamic analysis of a skeet-inspired vehicle to achieve a spiral scanning detection motion

A short cylindrical vehicle (the ratio of length to diameter is less than 2) equipped with an outer/inner detector is developed, which is inspired by the Tennis racket theorem and Olympic skeet shooting sports to achieve a regular scanning spiral on the ground. The sensitivity of the asymmetric mass distribution of the skeet-inspired vehicle (SIV) to the spatial position of the inertial principal axis is evaluated. Subsequently, a dynamics model with six degrees of freedom for the SIV at a large initial angle of attack (≈60-90°) is established. The numerical results of solving the dynamic differential equations indicate that the special initial conditions—namely, high initial flying velocity and rotational speed—are prerequisites for achieving the regular scanning spiral. Additionally, the analysis demonstrates that asymmetric mass distribution, rather than asymmetric aerodynamics, serves as the key factor in achieving the regular scanning spiral in the present skeet-inspired vehicle. Our new strategy, using the principal axes as the initial rotation axis, offers better scanning performance (such as a larger detection area, faster scan frequency, and more stable scanning motion) compared to the other platforms (e.g., rotating decelerators with wings or parachutes) that rely on asymmetrical aerodynamics. The analyses can provide guidance for the structural design of various types of spiral scanning vehicles.