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.