Multi-Robot Systems for Electric Power Inspection: A Review of Cooperative Perception, Collaborative Planning, and Coordinated Execution

Electric power systems are expanding toward higher voltage levels, larger renewable-energy bases, denser urban substations, and increasingly complex transmission corridors. These trends make inspection more frequent and more demanding, while conventional manual patrols and single-robot deployments remain constrained by safety risks, limited coverage, endurance, and fragmented situational awareness. Multi-robot systems offer a promising pathway for electric power inspection by combining heterogeneous platforms, distributed sensing, coordinated planning, and human-supervised autonomy. This review synthesizes recent progress in multi-robot inspection for power transmission lines, substations, distribution networks, and related grid assets, with particular attention to transmission corridors and substations where heterogeneous cooperation is operationally valuable. Following a Sense–Think–Act framework, we organize the literature into three interconnected components: cooperative perception for spatial and semantic understanding of grid assets; collaborative planning and task allocation for large-scale, risk-aware inspection; and coordinated execution with human oversight in safety-critical, often energized environments. We highlight how unmanned aerial vehicles (UAVs), unmanned ground vehicles (UGVs), climbing robots, and fixed robotic stations can complement one another in inspection workflows, from wide-area patrol and defect localization to close-range verification and maintenance support. We also discuss persistent challenges, including electromagnetic compatibility, reliable localization near metallic structures, multimodal data fusion, battery endurance, communication robustness, minimum approach distances, cybersecurity, benchmark scarcity, and the need for assurance mechanisms that allow operators to understand, trust, and intervene in multi-robot decisions. Finally, we outline a roadmap for moving from isolated demonstrations toward deployable, human-centered, and grid-integrated multi-robot inspection systems.