Unified flexible prescribed performance control for actuator-constrained systems through an event-triggered mechanism

This paper proposes a unified flexible prescribed performance control (UFPPC) scheme for actuator-constrained systems. The scheme features parameterized adjustment capability for initial prescribed performance boundaries (PPBs), which can be configured in the following four forms: e0∈−∞,+∞, e0∈−∞,Fu0, e0∈Fl0,+∞ or e0∈Fl0,Fu0, where e0 represents the initial tracking error, and Fu0 and Fl0 denote the lower and upper initial PPBs, respectively. Unlike existing FPPC schemes, the proposed scheme innovatively integrates an event-triggered mechanism (ETM) into the PPC framework, where its intuitive triggering logic enables dynamic PPB adjustment without relying on auxiliary system integration completion. Notably, PPB relaxation does not occur instantly during saturation transients but is conditionally activated based on ETM thresholds, with only unilateral PPB relaxation applied. These distinctive features not only address the fragility issue of prescribed performance control under input saturation but also significantly mitigate the performance degradation associated with the existing FPPC schemes. Simulation results validate the effectiveness and superiority of the proposed scheme.