  This paper focuses on the issue of how to realize spacecraft attitude control
with guaranteed performance while conspicuously reducing the actuator acting
frequency simultaneously. The prescribed performance control (PPC) scheme is
often employed for the control with guaranteed performance. However,
conventional PPC controllers are designed from the perspective of continuous
system, which contradicts the "discrete" control logic in actual spacecraft
control system, and such a problem limited the application value of PPC scheme
in actual applications. In order to significantly lower the actuator acting
frequency while still maintaining the desired performance, a composite
event-trigger mechanism is proposed for this issue, turning off the actuator
and eliminating unnecessary control output under appropriate conditions.
Further, the proposed composite event-trigger mechanism is combined with a
prescribed performance control scheme, constructing a complete controller
structure for solving the presented issue. Meanwhile, a special performance
function is designed to provide mild transition process. Based on the proposed
scheme, a specific backstepping controller is further developed as a
validation. Finally, numerical simulation results are presented to validate the
effectiveness of the proposed scheme.
