Paper Title
Role of RV Gears in Robotic Actuation and Power Transmission: A State-of-the-Art Review

Abstract
This paper presents a comprehensive state-of-the-art review of RV (Rotate Vector) gear mechanisms and their critical role in robotic actuation and power transmission systems. RV gears have become a key enabling technology in industrial, collaborative, medical, and service robots due to their high torque density, low backlash, high stiffness, and robustness under dynamic loads. The review traces the evolution and widespread adoption of RV gear technology, explaining its fundamental structure and working principles. Key performance characteristics such as precision, efficiency, load-bearing capacity, and dynamic behaviour are critically examined and compared with other precision gear mechanisms. Recent research advances in modelling, design optimisation, and condition monitoring of RV reducers are also discussed. Furthermore, the paper identifies existing challenges, including efficiency losses, modelling complexity, manufacturing constraints, and limitations in health monitoring techniques. Based on these insights, potential future research directions are outlined to enhance the performance, reliability, and applicability of RV gear-based actuation systems for next-generation robotics. Keywords - RV Gears; Robotic Actuation; Power Transmission; Cycloidal Reducers; Precision Gear Mechanisms; Industrial Robots; Collaborative Robots; Torque Density; Backlash Reduction