Distributed Event-Triggered Attitude Estimation Without Angular Velocity Measurements

In this article, a distributed event-triggered attitude estimation problem is considered for multiple rigid body systems on $\mathbb {SO}(3)$. The error in attitude estimation converges asymptotically to a common orientation among multiple rigid body systems, based on relative attitude measurements under undirected graphs. To eliminate the reliance on direct angular velocity measurements, a cascaded estimation scheme is proposed, employing indirect angular velocity estimation through a single vector measurement that is readily accessible using accelerometers or magnetometers. An event-triggered condition, grounded in clock variables, is proposed to reduce the communication and computation requirements associated with the attitude estimation. Subsequently, a rigorous convergence analysis of the attitude estimation errors is conducted, relying upon a stability criterion of invariant sets for cascade-connected systems. Furthermore, a self-triggered condition is developed to overcome the challenge of continuous monitoring throughout the event detection process. Ultimately, the efficacy of the proposed framework is validated through a numerical simulation encompassing multiple small satellites.