Self-tuning adaptive active disturbance rejection pitch control of a manta-ray-like underwater glider

In this paper, a self-tuning adaptive active disturbance rejection control (ADRC) algorithm for the pitch angle control of a new manta-ray-like underwater glider-"NPManta II" is proposed. First, a new dynamic model of NPManta II is established, which quantifies the influence of installation error, bladder volume change and position change of the moving internal mass. Second, a linear extended state observer with parameter self tuning based on the least mean square algorithm is designed. Third, a control-switching strategy is applied during posture transition to avoid inaccurate compensation of the control input. Finally, simulations and sea trial of the proposed adaptive ADRC controller and proportional integral differential controller are presented. The results indicate that the parameter converges quickly. The adaptive ADRC controller can effectively compensate for the control input, and move the internal mass to the optimal equilibrium position quickly and accurately, thus avoiding unnecessary movements to save energy.