由于低速航行时舵效较低，潜航器水平控制面产生的升力不足以抵消其在近水面时所受的波吸力扰动，所以引入压载水机构改进深度控制系统的性能，从而使其具有过驱动特征.本文提出了适用于这种过驱动控制系统的复合控制策略，其中前馈控制器输入为由扰动观测器估计的不平衡力，输出为压载水质量；反馈控制器输入为深度偏差，输出为水平舵偏转角.水下压载试验结果表明，扰动观测器可以精确地估计潜航器所受的不平衡力.水池自航试验结果表明，基于复合控制策略的潜航器深度控制系统具有较好的控制性能.
Due to low effectiveness of both bow and stern planes at low speeds, the near-surface suction force experienced by an underwater vehicle can hardly be counteracted by lifting forces generated by the control surfaces. To improve the performance of depth control system, therefore, a variable water ballast mechanism is introduced and thus leads to an over-actuated characteristic. A composite control scheme is proposed for such an over-actuated control system. The input of the feedforward controller is the disturbance force, which is estimated by the disturbance observer, and the output of the feedforward controller is the mass of ballast water. Besides, the input of the feedback controller is the depth error and the output of the controller is the deflection angle of control surfaces. The results of underwater tests show that the disturbance observer can accurately estimate the unbalanced force on the underwater vehicle, and the self-propelled water tank tests also show that depth control system of underwater vehicle based on composite control strategy has good control performance.
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