• 摘要: Stewart平台具有六自由度运动特性,既可用于隔振,也可用作跟踪平台。但是隔振功能要求系统带宽低,而跟踪功能则要求系统带宽高,二者的矛盾使得使用具有隔振功能的Stewart平台很难实现高精度跟踪。为了解决这一技术问题,引入高带宽的倾斜校正系统,构成双阶控制结构,以提高精度。传统的双阶控制需设计解耦环节,需要独立的测量传感器实现分级控制。本文提出了一种基于单传感器的控制方法,对传统的双阶结构进行改进,避免解耦环节,实现对Stewart-TTM高精度稳定闭环。为了进一步提高系统在带宽内的跟踪精度,设计PI-PI控制器经理论分析以及实验验证:基于单传感器测量的Stewart的双阶控制结构既能够满足隔振要求,又能够实现高精度跟踪控制。

       

      Abstract: The Stewart platform has six degrees of freedom motion characteristics and can be used as both vibration isolation and tracking platform. However, the vibration isolation function requires low system bandwidth, while the tracking function requires high system bandwidth, which makes it difficult to achieve high precision tracking using the Stewart platform with vibration isolation function. To solve this technical problem, a high-bandwidth tilt correction system is introduced to form a two-stage control structure, so as to improve the accuracy. The traditional two-stage control needs to design decoupling link and independent measurement sensors to achieve hierarchical control. In this paper, a control method based on a single sensor is proposed to improve the traditional dual-order structure to avoid decoupling and achieve a high-precision closed-loop for the Stewart-TTM. In order to further improve the tracking accuracy of the system at low frequencies, a PI-PI controller is designed. Theoretical analysis and experimental verification show that the Stewart dual-stage control structure based on image measurement can not only meet the requirements of vibration isolation, but also achieve high-precision tracking control. Compared with the traditional PI controller, the PI-PI control proposed in the tilt correction system can effectively improve the tracking accuracy.