Abstract: In order to solve the problem of reduced docking accuracy of the refueling port caused by residual vibration at the end during the operation of the autonomous filling arm of the oil tank truck, which affects the efficiency and safety of the operation, the parameters of the spring type balance mechanism in the filling arm are designed and optimized. First, a dynamic model of an autonomous refueling arm considering joint flexibility is established, and the influencing factors of residual vibration are analyzed based on simulation tests. Then, the maximum output tension required by the balance mechanism is calculated based on the derivation of the balance torque of the filling arm, and the initial design parameters and range of the balance mechanism are determined accordingly. Finally, the optimization of the design parameters for balance mechanism is achieved with the objective of minimizing the bias torque of the filling arm and the volume of the balance mechanism based on genetic algorithm. The numerical test results show that compared to the filling arm without a balance mechanism installed, the driving torque of the arm joint and the end effector following deviation are reduced in the filling arm with an optimized balance mechanism installed. Moreover, when the hydraulic cylinder extension distance R_i=‒40, the maximum amplitude at the end of the filling arm in the Z-axis is reduced by 10.67mm, which is 71.2% less than the maximum amplitude received without a balance mechanism installed. The time required for complete attenuation of the vibration amplitude is also reduced by 5.18s compared to the filling arm without a balance mechanism, which verifies the effectiveness and superiority of the designed and optimized balance mechanism in suppressing residual vibration at the end of the filling arm. The experimental results further verified the effectiveness of parameter optimization for the balance mechanism of the autonomous refueling arm.

Key words: autonomous filling arm, balance mechanism, flexible joints, residual vibration suppression, parameter optimization