摘要
大型铸锻件表面打磨存在结构尺寸大、表面复杂、人工作业强度高等问题,现有的打磨机器人系统虽然可以实现大型铸锻件的打磨作业,但存在占地面积大、灵活性差以及设备成本高的问题;本文针对以上问题,提出了一种融合移动平台、桁架式折展结构、串联机械臂、并联自适应打磨头的大型铸锻件表面打磨机器人系统平台,具有打磨范围大、占用空间小,布置灵活等特点,可以有效兼顾各种不同尺寸的大型铸锻件表面打磨需求。基于D-H(DenavitHartenberg)法对等效后所得到的8关节串联机构进行正逆运动学分析,采用数值法分析了混联机构整体工作空间,得到单机械臂工作状态下的打磨范围;基于矢量法对末端被动式并联打磨头建立运动学模型,并进一步分析了在串联机械臂保持一定姿态时并联打磨头的工作空间;研究被动式并联打磨头末端负载与驱动关节自适应调节之间的理论联系,优化气压阻尼系统的整体负荷状态;基于机械臂运动学模型获得关节速度及加速度,以机械臂整体功耗为优化目标建立能耗函数,分析得到平面打磨时打磨机器人在不同轨迹下的整体功耗,并通过数字算例与仿真计算验证了优化方程的合理性。基于ADAMS仿真模型对上述分析进行仿真验证,证明了桁架式混联打磨机器人设计与理论分析的合理性,为大型铸锻件打磨机器人设计开发提供了参考。
Objective The demand for automated surface grinding of large castings and forgings continues to increase with production scale and quality requirements.Conventional grinding robot systems,while functional,present significant limitations:large spatial footprint,poor adaptability to diverse workpiece sizes and shapes,and high investment and maintenance costs.These constraints hinder their application in space-and cost-sensitive manufacturing.Therefore,this research introduces a truss-based hybrid grinding robot system that combines a wide operational reach with a compact layout,ensures high stiffness at the grinding head for precision,and adapts to varied workpiece sizes and complex geometries.The study presents an innovative structural configuration,a complete theoretical framework,and simulation-based validation,making contributions to industrial robotic grinding.Methods The design process started with functional decomposition,including omnidirectional mobility,an extendable and retractable structure for large workpieces,a high-reach manipulator for complex positioning,and a grinding end-effector that maintained constant contact force over varying surfaces.The system integrated:1)an omnidirectional mobile platform that allowed free movement without reorientation constraints;2)a truss-type folding structure that provided a deployable framework expanding the workspace while minimizing the idle footprint;3)a serial robotic arm that offered large reach and positioning flexibility;and 4)a parallel adaptive grinding head,a passive parallel mechanism with pneumatic damping that ensured constant-force compliance and high stiffness.The serial arm and parallel head were modeled as an equivalent eight DOF hybrid mechanism,combining the stiffness and load capacity of parallel kinematics with the reach of serial designs.Forward and inverse kinematics were developed using the Denavit‒Hartenberg(D‒H)method to map joint space to Cartesian space.The workspace of the system and the single-arm grinding range were analyzed to define operational limits and optimal deployment.The passive parallel head was modeled separately using the vector method to assess the workspace under fixed arm postures,which enabled optimization of adaptability without affecting positioning.For constant-force grinding,mechanical and pneumatic conditions for adaptive drive joint adjustment under varying end-loads were examined.Pneumatic damping was optimized so that variations on the constant-pressure side yielded stable trends on the floating side,ensuring surface-contact stability.For energy efficiency,the hybrid arm’s kinematic model derived joint velocities and accelerations during grinding tasks.An energy consumption function was formulated with total arm power as the optimization objective.Case studies of linear grinding evaluated power patterns.Finally,the design and models were validated through an ADAMS virtual prototype that simulated realistic motions to verify kinematics,workspace,constant-force behavior,and energy use.Results and Discussions Workspace analysis confirmed that the truss-folding structure greatly extended the operational range without a proportional increase in footprint,enabling grinding of large and irregular workpieces.For single-arm operation,the reachable range was quantified,supporting task allocation in dual-arm setups.The passive parallel head maintained stable floating-end pressure under constant-force control,validating pneumatic optimization and ensuring consistent surface contact for uniform removal and finish.Simulations confirmed the kinematic accuracy of the serial and parallel subsystems,with minimal deviation between theoretical and simulated outcomes.The hybrid model achieved the intended stiffness and reach.Energy analysis demonstrated that spiral grinding trajectories consumed more power than serpentine paths in straight line grinding,which highlighted the impact of trajectory on energy usage and provided guidance for task planning.The omnidirectional base enabled rapid repositioning between zones,reducing idle time and improving coverage.The truss-folding design enhanced adaptability when shifting between large flats and contoured areas without requiring full disassembly or repositioning.Conclusions The truss-based hybrid grinding robot integrates the advantages of parallel and serial configurations,delivering high stiffness and wide coverage.The folding truss design accommodates large workpieces while maintaining a compact footprint when not in operation.Complete kinematic,workspace,energy,and pneumatic control models were validated through simulation.The system adapts to varying sizes and shapes while ensuring precision and surface quality.In addition,the modeling framework is transferable to other hybrid robotic designs.In practice,this approach enhances productivity,reduces labor demands,and improves quality consistency in large-scale surface finishing.Key innovations include the following:eight-DOF hybrid mechanism modeling of a passive parallel head and serial arm as a unified analytical framework;pneumatic damping optimization for stable floating-end pressure under varying inputs,advancing constant-force compliance in grinding;integration of truss-folding structures into mobile robots to achieve large workspaces with minimal idle footprint;and trajectory-dependent energy consumption analysis that informs energy-efficient path planning.The research contributes both a practical robotic design and analytical tools applicable to various automated manufacturing processes involving large and complex workpieces.
作者
刘毅
丰宗强
毛崇博
韩伟达
杨长安
马启凡
LIU Yi;FENG Zongqiang;MAO Chongbo;HAN Weida;YANG Changan;MA Qifan(School of Mechanical Engineering,Hebei University of Technology,Tianjin 300130,China;Laboratory of Parallel Robotics and Mechatronic Systems in Hebei Province,Yanshan University,Qinhuangdao 066004,China)
出处
《工程科学与技术》
北大核心
2025年第5期320-332,共13页
Advanced Engineering Sciences
基金
国家自然科学基金项目(U2037202
52075466)。
关键词
大型铸锻件
打磨机器人
运动学分析
自适应控制
轨迹优化
large castings and forgings
polishing robot
kinematic analysis
adaptive control
trajectory optimization
作者简介
刘毅(1991-),男,博士.研究方向:机器人理论及应用、机电一体化集成与控制.E-mail:17803332154@163.com;通信作者:丰宗强,实验师,E-mail:zqf@ysu.edu.cn。
