Robonaut Repositioning Device

Photo of Ben Fulcher 
Alan Openshaw
Robert (RJ) Taylor - Team Leader Students: Ben Fulcher Alan Openshaw Robert (RJ) Taylor - Team Leader

Sponsor: NASA

Date: Spring 2010

Requirements:
The designed devices must adhere to several additional constraints. First, R2 should be placed onto the surface of the moon oriented parallel with the gravity vector. The designs must also account for up to 12 degrees of surface slope. Sizing and mass considerations are important as the device must fit within a 145 inch diameter circle and the center of mass of the entire Lander should not shift more than 2 inches after adding the payload. In addition, the concepts will experience forces of up to 6g in compression, 2g in tension, and 2g laterally during flight. For the purposes of attaching the design to R2, there are several "hard points" on its body that NASA would prefer the team to use. These locations are its shoulders, hips, and neck. To power the repositioning device, the Lunar Lander will provide a 24V battery. A safety factor of 1.5 is expected for all calculations.

Problem:
Reposition a humanoid Robonaut (R2) from a Lunar Lander to the surface of the moon. During the deployment sequence, R2 is required to pause a set distance above the surface in order to exercise its limbs. The Robonaut must then be placed feet first on the lunar surface. NASA has proposed two different in-flight mounting orientations for the Robonaut on the Lander: lying horizontally on the upper face of the Lander and mounted to a side face of the Lander. Repositioning and mounting devices must be designed for each mounting orientation and a final recommendation for the preferred position should be given.

Solution:
The solutions utilize a four-bar mechanism for each orientation. For the horizontal mount, the design uses an electric motor and drive system to first rotate R2 90 degrees. After R2 has been positioned parallel to gravity and NASA tests its limbs, the four bar mechanism lowers R2 to the lunar surface supported by an electric motor drive. The four bar mechanism is attached to a sub-frame that connects with R2's shoulders and hips. The vertical orientation also uses a four bar mechanism that attaches to R2's shoulders and hips. The downward motion is started with a push provided by an electric actuator, and gravity both lowers and extends R2 simultaneously. An electric brake is used to control the downward motion. A solenoid pin locks R2 and the bar mechanism upright during flight and again after rotating 90° for exercising. After NASA tests R2's limbs, the solenoid is released and gravity carries R2 to the lunar surface, again controlled by an electric brake with the possible aid of a spring and damper. R2 will need to be mounted so that it will not sustain any damage during lift-off, flight and landing. The team designed a memory or temper foam "body-surrounding" mold to secure and dampen the Robonaut. Several nylon retraining straps will also secure R2 much like seat belts secure passengers of automobiles. After the Lunar Lander safely lands on the surface, an electric current is applied to resistively heated wires, causing the wires to heat and melt through the nylon. The repositioning device then removes R2 from the foam mold and places R2 on the lunar surface.

Images related to the project:

Photo related to Robonaut Repositioning Device project
Photo related to Robonaut Repositioning Device project
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