Improved FWH Path-Planning Algorithm Based on Multi-Strategy Enhancement for AUVs Operating in Coral Reef Areas

In this paper, an improved fixed-width histogram (IFWH) algorithm with multi-strategy enhancement is proposed for simulation-based AUV path planning in complex underwater environments. A multi-constraint optimization framework considering propulsion energy consumption, obstacle threats, terrain collision risks, and maneuverability constraints is established. Chaotic population initialization, adaptive global-local search transfer, quadratic interpolation, and spiral local refinement are integrated to enhance population diversity and trajectory smoothness. Numerical simulations are conducted under current-free terrains, overlapping seabed-current conditions, and environments with static and dynamic obstacles. Compared with A*, FWH, IPSO, and SVF-RRT*, IFWH reduces the average terrain slope by 43.91%, 47.24%, 44.94%, and 43.71%, respectively, and decreases estimated propulsion energy consumption by 35.29%, 37.38%, 24.66%, and 35.93% in current-free Scenario A. Under overlapping seabed-current conditions, IFWH achieves a 100% success rate over 30 independent trials, obtaining average slope angles of 15.58° and 18.73° with propulsion energy costs of 1163.57 J and 1116.99 J, respectively. In mixed environments, all trials are completed without collision, with average planning times of 1.674 0.700 s and 0.692±0.053 s under following- and rotary-current conditions, respectively.