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This study introduces a novel motion planning framework for over-actuated underwater vehicles that minimizes disturbances caused by thruster operation, which can degrade image quality during 3D reconstruction tasks. By leveraging the redundancy in thruster configurations, the method optimizes thrust allocations to reduce particle velocity in target regions, achieving significant improvements in image fidelity. The results demonstrate a 67% reduction in target-region particle velocity and a 55% improvement in reconstruction accuracy, validating the effectiveness of the approach through extensive trials.
Reducing underwater turbulence by 67% could revolutionize how we capture high-fidelity images in delicate environments.
Underwater robots often operate near delicate targets where high-power thrusters resuspend sediments and induce turbulence, degrading image quality at the sensor input. Conventional controllers optimize vehicle-centric objectives, such as tracking and stability, without accounting for the impact of actuation on sensing. We address this actuation-to-perception coupling by exploiting redundancy in over-actuated platforms. For an eight-thruster ROV, multiple thrust allocations can yield the same motion; we search this null space to minimize predicted disturbance in a task-relevant target region while enforcing motion constraints. Our method uses a control-oriented thruster-wake proxy derived from actuator-disk theory with directional attenuation and validated by PIV ($R^2 = 0.99$ near the wake axis; $R^2>0.82$ in the primary wake region), together with a real-time redundancy-resolving allocator running at 10 Hz (45 ms/solve). Across 440 trials, the approach reduces target-region particle velocity by 67% ($p<0.001$), improves 3D reconstruction RMSE by 55% versus a disturbance-unaware baseline ($1.9 \pm 0.4$ mm vs. $4.3 \pm 1.8$ mm), and achieves a 98.5% reconstruction success rate. The framework supports autonomous scanning, which is quantitatively evaluated, and operator-assisted inspection, which is demonstrated in the supplementary materials.
