GROLO: Realistic Range-Based Localization for Mobile IoTs Through Global Rigidity

Abstract

We study the realistic problem of range-based localization for mobile Internet of Things (IoT) without using GPS. This problem arises from the real-world applications and is characterized by the following three challenges: 1) inaccurate devices, such as the low cost motion sensors and moving parts in the mobile IoT nodes, make it infeasible to localize the nodes using their speed and direction; 2) when a team of IoT nodes keep moving, some nodes may get lost and be disconnected from the network due to the large accumulated errors in the distances; and 3) although the theory of global rigidity ensures the position uniqueness of nodes, there are still nonlocalizable nodes in a globally rigid graph. To address these challenges, we propose a distributed localization protocol, called GROLO. GROLO is able to perform efficient distributed localization through an adaptive global rigidity formation maintenance mechanism especially designed for the resource limited IoT nodes. GROLO is able to localize all of the nodes periodically in a mobile IoT by short distance adjustment. Furthermore, GROLO requires only necessary additional neighbor distance measurements. We evaluated GROLO and other localization protocols using both simulated nodes and ten real mobile nodes in an IoT. The results show that GROLO is promising for the localization and formation control with inaccurate mobile IoT in realistic environments.