Heterogeneous agricultural robots: a review of collaborative sensing and control, challenges and opportunities

A critical shift towards improved efficiency is currently taking place in modern agriculture, sustainability, and intelligence, driven by population growth, resource constraints, labor shortages, and increasing environmental pressure. Agricultural robots, especially heterogeneous robotic systems, have emerged as key enablers of this transformation by enabling precise, automated, and large-scale operations. This paper presents a comprehensive review of collaborative sensing and control technologies for heterogeneous agricultural robots working in both structured agricultural environments (greenhouses, orchards, and facility cultivation) and representative field farming scenarios. Focusing on recent advances over the past three years, we systematically analyze five representative robotic platforms: sprinkler irrigation robots, unmanned ground vehicles (UGVs), unmanned aerial vehicles (UAVs), agricultural robotic arms, and underground robots, from the perspectives of sensing, control, and cooperative operation. The review highlights key control methodologies, including intelligent path planning, adaptive and learning-based control, visual navigation, multi-sensor fusion, and energy-aware optimization. Furthermore, air-ground-underground integrated systems are discussed as an emerging paradigm for full-space agricultural coverage. Beyond technological progress, this paper identifies critical challenges in heterogeneous agricultural robot systems, including cooperative communication reliability, real-time safe control under dynamic environments, energy and endurance constraints, and system-level security. Finally, future research directions are outlined, emphasizing integrated communication and sensing, dual-arm and multi-arm collaborative manipulation, and heterogeneous multi-robot cooperative control frameworks.