一种用于多自由度非线性间隙值识别的改进恢复力曲线方法

Modified Restoring Force Surface Method for Clearance Identification in Nonlinear Multi-degree-of-freedom Systems

在机械系统中,间隙无处不在,由间隙引起的接触非线性往往会严重影响系统的动态响应精度,从而降低系统的动力性能。如果能利用系统动态信息识别出间隙大小,就能为机械系统的间隙控制提供依据。针对多自由度含间隙非线性系统,提出一种结合传统恢复力曲线方法与矩阵行空间正交投影技术的间隙值辨识方法。通过激励力和响应加速度得到传统意义下的恢复力,将该恢复力投影到各非线性位置上,绘制投影恢复力关于对应位置位移的曲线,由曲线的拐点就可以准确地识别间隙值。经过仿真验证了该改进方法的可行性,并与其他方法进行对比显示了该方法的优越性。在设计的含间隙悬臂梁试验台上进行参数辨识试验,验证了该方法在真实试验条件下的有效性。

Clearance is ubiquity in the mechanical system. The contact nonlinearities which are caused by the clearance can significantly affect the dynamic response, and eventually degrade the dynamic performance. If the parameter of the clearance nonlinearity can be identified by taking advantage of the equipment dynamic information, the system can be adjusted to control the influence of the clearance nonlinearity. Based on the multi-degree-of-freedom（MDOF） system with clearance, a modified method which combines the traditional restoring force surface（RFS） method and the orthogonal projection technology in the matrix row space is proposed to identify the clearance value. For the modified method, the traditional restoring force can be estimated by the excitation force and the acceleration response. The traditional restoring force should be projected on the nonlinearity location. The projection restoring force-displacement curve can be drawn, and the clearance size can be identified by inflection points. The feasibility of the proposed method is verified by the simulation, and the superiority is revealed by the comparison with other methods. The effectiveness of the proposed method is verified by the parameter identification experiments which are conducted on the designed testbed with adjustable clearance.