Warehouses and factories are required to improve their operational efficiency by using digital technology, and autonomous machines such as collaborative robots are being introduced into human work fields. In the future, we believe that a variety of autonomous machines will be introduced into living spaces, and a world will arrive where they will cooperate and coexist with people. To operate autonomous machines in a safe and secure manner, it is important to ensure the safety of humans and to prevent loss of work efficiency when heterogeneous systems including humans are mixed in an open field where the surrounding environment may change dynamically. By using an analysis method called security failure mode and effect analysis (FMEA), we have derived the safety and security requirements that are needed for autonomous machines to cooperate and coexist with humans. By clarifying the critical paths of target systems, we proposed and prototyped “Dependable connectivity” technology to operate systems safely and securely, then we verified its effectiveness on an actual machine. This research established the framework for designing systems in which humans and autonomous machines cooperate and coexist in an open field while considering the trade-offs between efficiency, safety, and security.