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The LMRs' Role LMR Design Systems Outline |
LMR Design Tree 
Legged Rover Systems Though a legged system presents an ideal solution for the Small LMRs, the Medium LMRs will need a stronger support system. The heavier and larger Medium LMR would not benefit from the advantages of using a legged system. Legs reduce the work that needs to be made against friction. However, the roughness of the Martian surface is not as harsh for the larger, Medium sized LMR, as it is for the Smaller LMRs. The heavier Medium sized LMR will expend more power simply trying to stand up. This will likely incrase as the mass of the LMR increaseses with return samples. Also, as the medium LMR is not designed to enter smaller, more claustrophobic, areas on the Martian surface, it will not need the extra two collission detection leg sensors installed on the small LMRs.Wheeled LMRs The medium sized LMRs will use a wheeled system for traversing the Martian environment. One such wheeled system is the rocker bogie system used for Sojourner. This space-worhty, and rigorously tested, mobility system provides the ideal means of transportation of the medium LMRs. Using six wheels, four of which can be independently rotated for finer steering control ( 1996, Jet Propulsion Laboratory, California Institute of Technology and the National Aeronautics and Space Administration). This allows the Medium LMR to perform fairly complicated maneuvers without requiring too much maneuvering space. The wheeled system will very likely be more capable of supporting the LMRs weight and the extra weight of any samples picked up for sample return.The primary benefit of the Rocker Bogie system, however, is its ability to automatically account for objects in the LMRs path. The Rocker Bogie system is capable of negotiaing obstacles twice the diameter of the wheels. This is tremendously helpful in allowing the meidum LMR to easily navigate across complicated terrain with ease. This more than makes up for the lost frontal-leg object-detection feature available for the smaller legged LMRs. Indeed, the Rocker Bogie systems if the primary system used in NASA's future autonomous Mars missions. Hovercraft LMRs A hovercraft LMR was an early conecept we had for an LMR design. The possibility of designing a hovercraft LMR had the advantage of a smoother form of motion that would be capable of handling small obstacles. The problems of maintaining and inflated bubble and using a fan as the primary accelerating engine in the low-density martian atmosphere limit the hovercraft model of motion. Also, many practical issues, such as, ruggedness, and ensuring that the inflated bubble is not torn by the surrounding obstacles on the Martian surface, presented many problems.Nanorover LMRs This wheeled system of mobility deserves a separate entry on the mobility subtree. Nanorovers are very light-weight, very small, rovers, capable of not only traversing terrain, but also of communicaing, and taking video images of their surroundings. These nanorovers are being designed for asteroid reconnaissance missions at NASA's Jet Propulsion Laboatory and must take the low gravity and temperature exteremes of the asteroids into account. The nanorovers are capable of travelling in almost any position. They can be flip upside down and continue operating, and can maneuver their wheels to cross over obstacles. Such a mobitlity system, however, requires that the nanorovers be paritcularly small autonomous vehicles. Our medium sized LMRs will necessarilly have to be larger than these nanorovers. Source: Nanorover Technologies |
