In order to online estimate the state of charge (SOC) of lithium-ion battery pack in this paper. This article establishes a dual Kalman filter (DEKF) algorithms for it. We establish a battery model of state space expression based on Thevenin battery model and Kalman filter algorithms. We use least square method and DEKF algorithms to identify the parameters of battery model in order to improve the accuracy of battery model. It can make battery model reflect true state of internal battery well. It introduces the principle which is dual Kalman filter algorithm online estimate the state of charge. Finally, it verifies DEKF algorithm has better convergence and robustness which can effectively resolve the problems of initial estimates error and cumulative error issue.

The control system of laser engraving machine based on ARM processor realize the precise control of the two-dimensional stepping motor and the laser head. This article focuses on the proposed stepping motor speed and trajectory control algorithm, and meanwhile, the speed control adopt linear acceleration and deceleration control algorithm; Trajectory control, based on the traditional point by point comparison arc interpolation method, puts forward the improved algorithm which can effectively improve the interpolation speed and interpolation accuracy. The experimental results show that the method can improve the machining precision and machining efficiency of laser engraving machine, and also can realize the high precision carving.