Abstract
Fracture Robots (FracBots) prototype has been successfully designed, developed, fabricated and tested in the laboratory. They are magnetic induction (MI)-based wireless sensor nodes that have the inter-node wireless communication, sensing and localization estimation capabilities. FracBots are miniature devices that can operate as wireless underground sensor networks (WUSNs) inside hydraulic fractures to collect and communicate important data and generate real-time mapping. The energy source of the FracBots is a major challenge since the operational environment is the hydraulic fractures which impose a restriction on the size that doesn't allow enough space for the battery. In addition, the capability to extract the energy from a designate source is another key-role feature that has to be a function of the FracBots. In this regard, energy consumption analysis and evaluation has been done to ensure that all the FracBots have the required energy to work properly during the operation inside the hydraulic fractures. The electronic design of the FracBots must be highly efficient and capable of dramatically reducing power consumption. Thus, FracBots design is composed of ultra-low power electronic chips that enable a switch among an active mode, a deep sleep mode and a shutdown mode with automatic wake-up features (Low Power Modes (LPMs). Also, it includes an energy management unit that harvests surplus power stemming from the base station. This feature reduces the power consumption and ensure continuous operation. Based on our energy model and electronic design, deep analysis of the harvested and consumed energy is conducted in a laboratory testbed. Results of this study show the capability of the FracBots to harvest the required energy to operate and perform all the communications and sensing functionalities. Using ultra-low power electronic chips based on ferromagnetic technology (FRAM) and energy management unit reduce the power consumption of the FracBots by 50% at least.
