混联式名优茶采摘机械臂优化设计与试验

Optimized Design and Test of Hybrid Robotic Arm for Picking of High Quality Tea

摘要:

针对名优茶采摘对高精度、高灵活性机械臂的需求,设计了一种基于Delta并联机构与3自由度串联机构的混联构型茶叶采摘机械臂。首先,结合茶园环境与茶丛生长特性,通过几何法和D-H参数法分别建立了并联与串联机构的运动学模型,基于欧拉角变换实现了混联机械臂的整体运动学求解。其次,采用NSGA-Ⅱ多目标优化算法对机械臂结构尺寸进行优化,使全域姿态可操作度、区域姿态可操作度及全局灵巧度分别提升54.3%、81.3%和57.92%。进一步通过ADAMS动力学仿真和ANSYS拓扑优化,实现了主动臂减重27.62%,同时最大应力和变形量分别控制在2.118MPa和0.015mm以内,关节驱动力矩降低13.06%。样机试验表明,该机械臂重复定位精度为0.036mm,单芽采摘成功率为79%,平均耗时2.27s,验证了混联方案在名优茶采摘中的可行性。

Abstract:

Aiming to address the demand for high-precision, high-flexibility robotic arms in the picking of premium tea, a hybrid-configuration tea-picking robotic arm based on a Delta parallel mechanism and a 3-degree-of-freedom serial mechanism was designed. Firstly, considering the tea garden environment and the growth characteristics of tea bushes, kinematic models of the parallel and serial mechanisms were established by using the geometric method and the D-H parameter method, respectively. The overall kinematic solution of the hybrid robotic arm was achieved through Euler angle transformation. Subsequently, the NSGA-Ⅱmulti-objective optimization algorithm was employed to optimize the structural dimensions of the robotic arm, resulting in improvements of 54. 3% , 81. 3% , and 57. 92% in global orientation manipulability, regional orientation manipulability, and global dexterity, respectively. Furthermore, through ADAMS dynamic simulation and ANSYS topology optimization, the mass of the active arm was reduced by 27. 62% , while the maximum stress and deformation were controlled within 2. 118 MPa and 0. 015 mm, respectively, and the joint driving torque was decreased by 13. 06% . Prototype tests demonstrated that the robotic arm achieved a repeated positioning accuracy of 0. 036 mm, a single-bud plucking success rate of 79% , and an average cycle time of 2. 27 s, verifying the feasibility of the hybrid configuration for premium tea plucking.