六自由度水下机械臂设计与分析

Design and analysis of six-degree-of-freedom underwater manipulator

为了解决有缆水下机器人(ROV)上搭载的机械臂作业范围不大、水下作业能力有限的问题,对六自由度(6-DOF)水下机械臂进行了研究,设计了一种带有平动开合功能夹持手爪的六自由度水下机械臂,实现了主手对从手的关节驱动器(液压缸或摆动缸)进行位置控制的目的。首先,基于多目标优化规则对夹持手爪进行了计算,求解出液压缸最短行程在20 mm时即可实现手爪的120 mm平动开合范围目标;然后,建立了六自由度机械臂活动关节的D-H数学模型,对机械臂的正、逆运动学进行了求解;最后,采用Solid works软件对设计的机械臂进行了干涉检查,并利用MATLAB软件仿真分析了6个活动关节的运动轨迹,采用蒙特卡洛法求解了机械臂的工作空间范围,并进行了样机测试和水下实验。研究结果表明:机械臂的仿真模型位姿与三维模型位姿一致,机械臂的6个活动关节速度和加速度曲线都是光滑平顺的、无突变点,不存在超调现象;设计的六自由度水下机械臂夹持手爪可以按照预定指令进行120 mm开合运动,ROV上的从机械臂能够跟随主机械臂运动,加减速性能良好,各关节转角范围满足设计要求,可为下一步机械臂的结构优化奠定基础。

In order to solve the problems of small working range and limited underwater working ability of the robot arm mounted on the remote operated vehicle(ROV),the design of the six-degree-of-freedom(6-DOF)underwater robot arm was studied.A six-degree-of-freedom underwater manipulator with translational opening and closing function was designed,which realizes the position control of the joint driver(hydraulic cylinder or swing cylinder)of the slave hand by the master hand.Firstly,based on the multi-objective optimization rules,the clamping claw was calculated,and the 120 mm translation opening range of the claw could be achieved when the shortest stroke of the hydraulic cylinder was 20 mm.Then,the D-H mathematical model of the movable joint of the 6-DOF robot arm was established to solve the forward and reverse kinematics of the robot arm.Finally,the designed robot arm was checked by Solid works software,and the motion track of six active joints was simulated and analyzed by MATLAB software,and the workspace range of the robot arm was solved by Monte Carlo method.The prototype test and underwater experiment was carried out.The research results show that the position and attitude of the simulation model of the mechanical arm are the same as that of the three-dimensional model,the speed and acceleration curves of the six active joints of the mechanical arm are smooth,without catastrophe point,and there is no overshoot phenomenon.The clamping claw of the 6-DOF underwater robot arm can perform 120 mm opening and closing motion according to the predetermined command,the slave arm on the ROV can follow the movement of the main arm,and the acceleration and deceleration performance is good.The range of rotation angles of each joint meets the design requirements,which lays a foundation for the next structural optimization of the robot arm.