双控制方式下带缆水下机器人轨迹跟踪与水动力响应分析

Analysis on hydrodynamic response of a tethered underwater robot under two control manipulations

本文首先根据已有的脐带缆运动控制方程,通过引入与工作船和水下机器人连接点处边界条件和速度耦合关系,与水下机器人运动方程一同构成完整的水动力数学模型;其次提出收放脐带缆的前馈-反馈控制方法和调节螺旋桨转速的增量式PID(Proportion Integration Differentiation)算法,建立完整的带缆水下机器人系统水动力与控制模型;最后对所提出的模型进行数值模拟实验验证与运动控制操纵下的水动力分析。数值计算结果表明:本文所提出的带缆水下机器人系统水动力与控制模型是有效可靠的,垂向运动控制过程中,水下机器人纵摇角、横摇角和沉深的模拟值与实验值最大误差分别为2°、1°和-50 mm;对于PID算法,调节螺旋桨转速控制水下机器人对给定位置信息的跟踪响应效果,模拟值与实验值相差均不大;轨迹跟踪模拟计算沿水平(X轴)方向和竖直(Z轴)方向最大相对误差分别为10%和15%;水下机器人竖向(沿Z轴)运动主要由调节脐带缆长度的前馈-反馈策略决定,沿水平(X轴)方向的运动主要由调节螺旋桨转速的PID算法控制;机器人水动力载荷受其周围流场变化的影响,而流场的变化主要由机器人运动速度的改变和螺旋桨转速变化二者共同决定。

This paper proposes a hydrodynamic mathematical model of a tethered underwater robot system by introducing boundary conditions and coupling relations into the existed governing equations for umbilical ca⁃ble systems.A feed-forward and feedback control method was used for adjusting the length of the umbilical cable while the incremental PID algorithm was applied on regulating rotating speeds of propellers for estab⁃lishing the integral hydrodynamic and control model of a tethered underwater robot.The experimental valida⁃tion and hydrodynamic responses under the two control manipulations were simulated numerically.The simu⁃lation results showed that the proposed model was valid and reliable.In the depth control,the maximum erors of pitch,roll and submerged depth of the underwater robot between simulation and experiment are 2°,1°and-50 mm respectively.The errors of trajectory tracking simulations in X direction and Z direction are 10%and 15%respectively.The motion in Z direction of the underwater robot is determined mainly by the feedforward and feedback control strategy for the cable,and the motion in X direction of the underwater robot is primarily controlled by the PID algorithm for regulating the rotational speeds of the duct propellers.The hy⁃drodynamic loadings on the robot are influenced by the flow fields around the robot,and the changes of the flow fields are determined by the changes of the robot velocity and the propellers rotating speed.