机械臂柔性对接半物理仿真系统特性分析

Characteristics analysis of hardware-in-the-loop simulation system for manipulator flexible docking

摘要:

机械臂为数学模型的机械臂对接半物理(HIL)仿真系统会因为对接机构的高接触刚度导致系统不稳定,为准确模拟对接过程,提出将机械臂等效为六维弹簧机构实物来模拟机械臂的对接过程,并对该HIL系统特性进行分析. 用根轨迹法对比分析机械臂为数学模型和六维弹簧机构实物的HIL系统参数对稳定性的影响；应用-20 dB/dec段穿越理论得到系统具有良好特性时的参数配置关系,利用稳定判据得到HIL仿真系统的稳定条件,采用3D根轨迹法和仿真分析得到系统对接动力学频率模拟能力,分析了提出的HIL仿真系统的稳定性和复现精度. 实验结果表明:在对接机构接触刚度较高时,机械臂为数学模型的HIL仿真系统不稳定,而机械臂为实物的HIL仿真系统保持稳定；仿真分析结果与实验结果吻合,说明了机械臂由数学模型变为六维弹簧机构实物对改善系统特性的有效性,以及提出的HIL仿真系统分析结论的正确性.

Abstract:

Manipulator docking hardware-in-the-loop(HIL) simulation system with the manipulator as a mathematical model will cause instability due to the high contact stiffness of the docking mechanism. To accurately simulate the docking process, the manipulator is equivalent to a six-dimensional spring mechanism during the docking process and the characteristics of HIL system are analyzed. Using root locus method, the influences of HIL system parameters with a mathematical model and a six-dimensional spring mechanism on the stability are compared. Based on the -20 dB/dec crossing frequency theory, the stability criterion, the 3D root locus method and the simulation analysis, the stability and reproduction accuracy are studied from three important aspects of the parameter configuration relation, the system stability condition and the dynamics frequency simulation ability. The experimental results show that when the contact stiffness of the docking mechanism is high, the HIL simulation system with a mathematical model manipulator is unstable but the HIL simulation system with a spring mechanism manipulator is stable; the analysis results obtained from the three aspects which satisfy the stability and reproduction accuracy are consistent with the experimental results. The effectiveness of changing manipulator from a mathematical model to a six-dimensional spring mechanism is illustrated.