基于MQTT- SM4掩码辅助加密算法的配电物联网安全通信

随着“坚强智能电网”、“泛在电力物联网”等战略的部署和发展建设，大量的电力采集设备、机器人、监控摄像头应用在配网作业场景中。因此，针对配网终端数量多和配网作业环境复杂多样化等因素，如何设计合适的通信架构对于保证配网数据的安全稳定传输尤为重要。首先，本文基于当前流行的物联网平台通信协议MQTT、CoAP和HTTP，从多个方面进行对比分析，并设计了一种新颖的配电物联网通信架构。进一步，针对安全性要求，我们基于国密SM4提出MQTT- SM4掩码辅助加密算法对配电物联网信息进行加密传输，通过会话密钥协商获取所需的掩码密钥和消息密钥，并协同计算出轮密钥用于加密。通过对MQTT- SM4掩码辅助加密算法进行加密测试和安全分析，仿真结果表明，本文设计方案能够有效提高配电物联网通信安全性和稳定性。     

A novel fixed-time sliding mode control for nonlinear manipulator systems based on adaptive disturbance observer

Considering that in the trajectory tracking control of a nonlinear robotic manipulator system, the control effect is easily limited by the initial state of the system, and the system has modeling error, unknown disturbance, and friction in the actual control, to overcome the above problems, a fixed-time sliding mode control (SMC) strategy based on adaptive disturbance observer (ADO) is developed in this paper. Firstly, feedforward compensation of the system is achieved by developing an ADO to accurately estimate the compound disturbances in the system. Second, a new fixed-time sliding mode (SM) surface is presented to overcome the singularity issue and accelerate the error convergence. In addition, to enhance the performance of the reaching phase, a variable exponential power reaching law (VEPRL) is developed, which can effectively adjust the convergence rate. Through rigorous theoretical analysis, it is shown that the system state can be stabilized at a fixed time, and an upper bound on the convergence time is also given. Finally, the effectiveness of the control method is verified by comparing it with different control schemes in simulation.