From Irrigation Prescriptions to Verified Water Delivery: Actuation-Aware MPC and Digital Twins for Moving Variable-Rate Sprinkler Systems

Variable-rate irrigation (VRI) prescribes spatially differentiated water demand. A moving sprinkler implements these prescriptions through travel speed, valve duty, pressure, and timing. This review examines how model predictive control (MPC), state estimation, sprinkler hydraulics, application measurement, and digital twins can support the conversion of a prescription into verified water delivery. Evidence, classified by function and validation setting, distinguishes direct irrigation MPC studies from transferable sensing, modeling, and equipment evidence. Irrigation MPC has progressed from soil water regulation toward forecast-, risk-, crop-value-, and space-informed prescriptions. Verification of machine-level delivery combines explicit execution models with independent measurements. Field and bench studies show that motion, pressure, valve timing, nozzle geometry, footprint overlap, and wind constrain delivery and its measurement, while independent application feedback remains uncommon. The review proposes a command-to-delivery sequence comprising actuation time demand, projection onto the machine-attainable field, and separate residuals for projection, command tracking, and application transfer. A control-coupled digital twin is proposed as a testable layer preserving time alignment, model versioning, and residual provenance, and translating supported updates into feasible actions or safe degradation. The proposed future evaluation pathway comprises independently measured delivery and claim-matched ablation, with multi-season trials for interannual benefit claims and representative fault tests for resilience claims.