State-feedback control of the SpaceHawk Earth-based lunar hopper

The SpaceHawk is an Earth-based model spacecraft designed to navigate the surface of the moon in a series of “hops”. By design, the nonholonomic dynamics of the SpaceHawk allow the use of full-state feedback linearization. The position and attitude states are decoupled via exact feedback linearization before being stabilized via proportional-derivative (PD) control. As a computationally inexpensive alternative to the exact linearization controller, an approximate linearization controller is designed to exclude the highly nonlinear attitude dynamics. Simulations show the approximate linearization controller performing comprably to the exact linearization controller despite the initial conditions being far from the origin. Satisfactory results are obtained for stability and tracking in the position and attitude states.