Landing Gear Design, Fabrication, and Testing for the Ingenuity Mars Helicopter

Abstract

This paper describes the development of the landing gear system for the Ingenuity Mars Helicopter. Ingenuity is a 1.8 kg co-axial helicopter which demonstrated the first powered, controlled flight at Mars on April 19, 2021. As part of the Mars 2020 mission, Ingenuity was deployed from the Perseverance Rover, which landed at Jezero Crater in February 2021. To ensure safe, autonomous landings on unfamiliar terrain in variable weather conditions without the need for an onboard obstacle avoidance system, the landing gear was designed to provide no less than 50 mm ground clearance when landing at velocities up to 2 m/s vertically, 0.5 m/s horizontally, and with angular rates up to 40 deg/s. The system consists of a composite central interface plate, spring-loaded deployment hinges, suspension spring flexures and dampers, and four hollow composite landing legs and feet, all of which were uniquely designed for conditions at Mars. Traveling with the Perseverance Rover required the landing legs to be folded into four unique positions within a compact not-to-exceed volume beneath the belly pan of the rover. During deployment from the Perseverance Rover, the helicopter's landing legs deployed passively and latched securely before Ingenuity could be released onto the Martian surface. In order to reduce bounce and angular rates upon landing, each leg employs a titanium spring flexure coupled with an annealed 1100-series aluminum damper which yields as the leg deflects by as much as 17 degrees, providing up to 80 mm of vertical travel. During the development and verification process of the landing gear system, an extensive test campaign was performed to validate structural properties, landing dynamics, and reliable actuation of the deployment mechanisms. A testbed to simulate varied Martian surface conditions was fabricated in a Vicon motion capture lab at AeroVironment's Simi Valley facility to evaluate touchdown dynamics across a wide range of landing conditions. In this paper, the authors will describe: 1.The conditions and surfaces that the landing gear system was designed to withstand; 2.Unique design features of the composite interface plate and leg hub, carbon clevis, deployment mechanism, suspension spring and damper, hollow carbon fiber leg tubes, and feet; 3.The unique challenges and solutions involved in stowing the landing gear within the strict and complex constraints of the available space and reliably deploying the landing gear in preparation for release onto the Martian surface; 4.Test procedures and results for the landing gear system's development and verification campaigns.