Tuning Hybrid Incremental Dynamic Inversion Control Laws using H∞ Loop-Shaping

Nonlinear Dynamic Inversion (NDI) control techniques provide a conceptually simple and modular control framework, making it an attractive technique for designing fight control laws with shorter design cycles. However, its lack of inherent robustness guarantees shifts the burden of the design from the synthesis to the analysis part. Conversely, H ∞ Loop-Shaping provides controllers with robust stability guarantees. This work proposes a novel framework leveraging the H ∞ Loop-Shaping Design Procedure to optimise a structured linear variant of Incremental Nonlinear Dynamic Inversion (INDI) control, a Hybrid IDI controller. The Hybrid IDI controller consists of a blend between classical model-based DI and sensor-based IDI. The proposed methodology is validated through the design of a pitch-rate controller for NASA’s X-29 experimental aircraft. Results demonstrate that the approach achieves robustness guarantees comparable to standard full-order H ∞ controllers while maintaining the simplicity and modular architecture of NDI-like structures, thereby combining the advantages of both techniques.