Multi-purpose mobile robots with a modular layout have become a hot research topic in recent years. The safe performance of these robot's operations is relying on the low-level cyber-physical system (CPS). In this paper, the scientific goals underscore the analysis of the computational (cyber) units for low-level real-time fault monitoring. The purpose of these units is to monitor control signals issued by other (cyber) units or sensors and if there is a safety-critical problem, then predefined actions can be triggered. The safety controller was built and tested on the TalTech iseAuto platform. Based on the results, a new multi-layer universal safety system was developed. In the first layer, all signals and messages are checked to be in a suitable range or order. The second layer detects if an accident is happening using crash sensors. The third layer includes remote control switches support. If a failure or malfunction occurs, the emergency action plan is executed to stop the vehicle safely.