Biblio

Modbus is a popular industrial communication protocol supported by most automation devices. Despite its popularity, it is not a secure protocol because when it was developed, security was not a concern due to closed environments of industrial control systems. With the convergence of information technology and operational technology in recent years, the security of industrial control systems has become a serious concern. Due to the high availability requirements, it is not practical or feasible to do security experimentation of production systems. We present an implementation of cyber-physical systems with Modbus/TCP communication for real-time security testing. The proposed architecture consists of a process simulator, an IEC 61131-3 compliant programmable logic controller, and a human-machine interface, all communicating via Modbus/TCP protocol. We use Simulink as the process simulator. It does not have built-in support for the Modbus protocol. A contribution of the proposed work is to extend the functionality of Simulink with a custom block to enable Modbus communication. We use two case studies to demonstrate the utility of the cyber-physical system architecture. We can model complex industrial processes with this architecture, can launch cyber-attacks, and develop protection mechanisms.

This paper is devoted to the choice and justification of a joint-level controller for a joint with intrinsic elasticity. Such joints show a number of advantages in terms of shock robustness, interaction safety, energy efficiency and so on. On the other hand, the addition of elastic element, i.e. a torsion spring, leads to oscillating behaviour. Thus, more elaborate controller structure is required. Active damping injection approach is chosen in this article to improve the joint performance and achieve smooth motion. A method to select controller gains is suggested as well which allows step-wise customization, by which either the settling time can be minimized or the motion can be made fully smooth. Finally, the controller performance is verified in simulation.