Research On Tip-over Stability Of Wheeled Mobile Dual-Arm Robot

The robot technology has become the focus of research at home and abroad.The development of robot technology can not only replace Chinese traditional industries and liberate people’s hands,but also improve Chinese comprehensive strength and influence.The wheeled mobile dual-arm robots are widely used in the field of mobile robots.The configuration of dual-arm and mobile-base can increase the flexibility and operability of the robot.They are widely used in families,medical treatment,shopping malls,restaurants and other fields.However,the wheeled mobile dual-arm robot is a kind of structurally unstable system.It has the possibility of tip-over under the coupling motion of arm / mobile platform and external interference especially for the mobile service robot with small-size support platform,large variation of system mass distribution and bearing additional load in work.Therefore,tip-over avoidanceis the primary condition for the mobile robot to complete the operation task normally.This paper mainly studies the tip-over stability of wheeled mobile dual-arm robot,which is analyzed and studied from four aspects: robot kinematics,robot dynamics,robot tip-over criterion and robot trajectory planning based on tip-over stability constraint.The research contents of this paper are as follows:(1)Kinematics modeling and analysis of robot.Firstly,the forward kinematics of the arm was modeled based on the screw theory,and the forward kinematics equation was deduced.Then,the inverse solution of the end of the manipulator was solved based on the combination of vector method and pose separation method.The forward and inverse kinematics model was simulated and verified with the help of MATLAB 2017 a software and ADAMS 2018 software,which showed the correctness of the kinematics modeling.Finally,the kinematics modeling of the differential mobile platform was carried out,and the Jacobian matrix of the differential mobile platform was deduced.(2)Dynamics modeling and analysis of robot.The Newton-Euler method was used to model the dynamics of the robot arm.The recurrence formula of the joint torque of the robot arm was deduced.Then,the dynamic model of the manipulator were simulated and verified based on MATLAB 2017 a software and ADAMS 2018 software.The joint torque calculation results of MATLAB software and ADAMS simulation results were compared and analyzed to verify the correctness ofrobot dynamic modeling.(3)Research on tip-over stability criterion of robot.The tip-over stability criterion for the robot was proposed from the tip-over moment of the robot based on the dynamic model of the manipulator.Then,the tip-over stability criterion proposed in this paper was compared with ZMPcriterion to verify the correctness and superiority of the proposed stability criterion.Finally,the tip-over stability of wheeled mobiledual arm robot was analyzed in three motion cases based on the stability criterion proposed in this paper.(4)Joint trajectory planning of robot based on tip-over stability constraint.Ajoint trajectory planning optimization model forthe robot was proposed.It took energy and time optimization as the optimization objective function and tip-over stability as the basic constraint condition.Then,the quintic B-spline interpolation method was used to plan the joint trajectory,and the NSGA-Ⅱoptimization algorithm was used to solve the robot joint trajectory planning optimization model to find the Pareto optimal solution.Finally,two optimization cases without considering tip-over stability constraints and considering tip-over stability constraints were set.The two optimization cases were analyzed and compared.A smooth and stable joint trajectory without overturning was planned.The system simulation experiments was conducted in Adams 2018 software to verify that considering tip-over stability constraint has practical significance to improve the stability of the robot.The research results of this paper will contribute to the follow-up research on mobile robot tip-over avoidance trajectory planning and tip-over compensation methods,and have positive academic significance for tip-over problem and trajectory planning in the field of wheeled mobile robot.Figure [61] table [11] reference [84]...