Fourth Industrial Revolution (IR4.0) depends heavily on the Internet of Things (IoT) and wireless sensor networks (WSNs). Through WSN, data in an industrial environment can be captured. Time synchronization is an important issue in WSN to ensure the correct sequence of the data collected. Besides, gauging on a common perceived time reference, local clocks on each node within any interconnected WSN should be able to initiate message exchanges. Referencing to an unsynchronized value of virtual global reference clock will render the nodes' communication and applications in WSN useless. In this work, a newly improved control theoretic consensus-based time synchronization algorithm for WSN known as time synchronization using sliding-mode control and proportional, integral, and derivative (TSMPID) is proposed. The novel algorithm uses an augmented sliding-mode control (SMC) in the skew and relative skew estimation schemes, which is a useful switching action, to provide a salient feature in guaranteeing finite-time convergence in synchronized virtual time clock estimation. A proportional, integral, and derivative (PID) term has been introduced in the offset estimation to improve the estimation performance. The main purpose is to achieve global clock synchronization with lower computational effort and reduced synchronization error. TSMPID has the characteristics of being totally distributed, asynchronous, scalable across different network topological structures and robust to ad hoc nodes deployment. Ad hoc communication link node deployment scenarios are simulated comprising five, seven, and nine WSN nodes. TSMPID requires low energy and exhibits a much lesser consensus error spike in comparison to other recent prior-art time synchronization schemes.
