To address the dual challenges of tracking accuracy and resource efficiency for quadrotor unmanned aerial vehicle (UAV) attitude control, an event-triggered based control strategy combining backstepping sliding mode control (BSMC) with a linear extended state observer (LESO) is proposed. With a quadrotor UAV dynamic model established via Euler-Newton equations, a BSMC which combines sliding mode control and backstepping is proposed to guarantee stability of UAV and a LESO is used for real-time compensation of total disturbances to improve tracking accuracy. Moreover, a time-varying threshold event-triggered (TVST) mechanism is also deliberately developed to reduce controller update frequency while maintaining the system performance. The proposed methed is an emulation one which significantly reduces the communication and computation burden and avoid the unnecessary wear and tear of the actuator. Simulations and experimental results demonstrate that the proposed control strategy achieves an effective balance between tracking accuracy and resource conservation.

Puppet is a popular declarative framework for specifying and managing complex system configurations. The Puppet framework includes a domain-specific language with several advanced features inspired by object-oriented programming, including user-defined resource types, `classes’ with a form of inheritance, and dependency management. Like most real-world languages, the language has evolved in an ad hoc fashion, resulting in a design with numerous features, some of which are complex, hard to understand, and difficult to use correctly. We present an operational semantics for $\mu$Puppet, a representative subset of the Puppet language that covers the distinctive features of Puppet, while excluding features that are either deprecated or work-in-progress. Formalizing the semantics sheds light on difficult parts of the language, identifies opportunities for future improvements, and provides a foundation for future analysis or debugging techniques, such as static typechecking or provenance tracking. Our semantics leads straightforwardly to a reference implementation in Haskell. We also discuss some of Puppet’s idiosyncrasies, particularly its handling of classes and scope, and present an initial corpus of test cases supported by our formal semantics.