研制一种基于Galfenol合金的智能悬臂梁结构,同时考虑粘合层对结构动态性能的影响,建立计及粘合层的分布参数动力学模型,该模型以电磁线圈为驱动源,为减小高频磁场造成的涡流损耗,设计一种叠片结构的U形驱动线圈对智能悬臂梁进行驱动,并通过试验对该结构下的动力学模型进行验证;由于分布参数模型状态输出变量与参考电压没有直接耦合,提出一种基于分布参数模型的滑模变结构解耦控制方法,通过对输出变量矩阵解耦可以实现输入与输出的直接耦合,同时针对柔性结构中存在的次谐波扰动,利用Lyapunov函数证明了在非匹配条件下控制系统的稳定条件,并通过仿真试验对结论进行验证,同时,以比例—积分控制作为对比试验,与提出的滑模变结构解耦控制进行对比,通过比较不同频率下的动态跟踪结果,证明了所提出的控制方法不仅解决了复合悬臂梁分布参数模型中的不耦合问题,同时可以有效抑制Galfenol合金的磁滞非线性,使系统可以较好地跟踪外界参考输入。
A smart cantilever structure based on Galfenol alloy is developed,and a dynamic distributed parameter model is built,which takes into account the influence of adhesive layer on the dynamic performance of structure.The proposed model,excited with magnetic coil,can be used to predict the dynamic behavior of the smart cantilever structure.In order to reduce the eddy current loss from high frequency magnetic field,a laminated U-shaped frame is adopted for the flux return path in the solenoid driven magnetic circuit.Since the state output variable of the distributed parameter model is not directly coupled with the reference voltage,a decoupling control method of sliding mode variable structure based on the distributed parameter model is proposed.Then direct coupling of input and output can be realized through decoupling of output variable matrix.Furthermore,in view of the subharmonic disturbance in the flexible structure,Lyapunov function is adopted to prove the stability condition of the control system under mismatch condition,and the conclusion is verified via computer simulation.Moreover,proportional-integral control is employed for comparison with the proposed control.It can be seen from the experimental tests that the proposed control method can not only solve the decoupling problem in the distributed parameter model,but also efficiently suppress the nonlinear hysteresis of Galfenol alloy,thus enabling the system to better track the external reference input.