Study On The Robust Adaptive Control Method Of Linear Motor Gantry System

Due to high-speed and high-precision features, linear motors have been widely used in transportation, military equipment, microelectronics and modern machinery manufacturing industry. However, linear motor of gantry system has kinds of parametric uncertainties and non-parametric uncertainties. In order to attenuate the influence of the uncertainties and disturbances on the system, we must take effective control strategy to achieve satisfying motion control performance.In this thesis, we consider the linear motor in dual-axis gantry system as the control object. The main work includes, firstly, a mathematical model based on the physical mechanism of linear motor is established; secondly, the model parameters of the dynamical system are obtained by designing the immersion and invariance (I&I) adaptive identifier and off-line parameter estimator based on the least squares method, respectively; thirdly, according to the cases of control direction to realize the robust adaptive control algorithm, the I&I manifold based robust adaptive controllers with known and unknown control gain are proposed, respectively, and the stability of the closed-loop system is analyzed as well; finally, in order to verify the effectiveness of the proposed algorithms, two different kinds of adaptive controllers are applied to the dual-axis linear motor gantry system. The main content of this paper includes the following aspects:(1) A mathematical model of the linear motor with parametric uncertainties and non-parametric uncertainties is established. According to the uncertainties in the model, an I&I adaptive observer which departs from the traditional adaptive control is realized by adding certain proper tuning function on parameter estimation such that the estimation error between the unknown parameters and their estimates converges to zero vicinity gradually.(2) The I&I robust adaptive controllers are proposed for the uncertainties in the linear motor system. This method avoids the complexity of the construction of Lyapunov function, which has simplicity. And the entire system is considered as a cascade of convergent estimator and disturbed system. In the presence of various disturbances, the boundedness of the parameter convergence, system state and signal are guaranteed by the robust control.(3) The I&I robust adaptive controllers with known and unknown control gain are proposed, respectively, and applied to control of the linear motor gantry system, respectively. The experimental results show that both the two controllers have good tracking performance. When the desired trajectory has an abrupt change, the output can track the change of the target quickly, which shows the better transient and steady-state performance.In this thesis, two I&I based robust adaptive controllers are proposed, which have satisfying control requirements and achieve the performance-oriented control objectives. In the presence of parametric uncertainties and various disturbances, linear motor gantry closed-loop system can track the target trajectory and have good transient and steady-state performance by using the proposed controllers.