Future human and robotic planetary expeditions could benefit greatly from expanded Extra-Vehicular Activity (EVA) capabilities supporting a broad range of multiple, concurrent surface operations. Risky, expensive and complex, conventional EVAs are restricted in both duration and scope by consumables and available manpower, creating a resource management problem. A mobile, highly dexterous Extra-Vehicular Robotic (EVR) system called Centaur is proposed to cost-effectively augment human astronauts on surface excursions. The Centaur design combines a highly capable wheeled mobility platform with an anthropomorphic upper body mounted on a three degree-of-freedom waist. Able to use many ordinary handheld tools, the robot could conserve EVA hours by relieving humans of many routine inspection and maintenance chores and assisting them in more complex tasks, such as repairing other robots. As an astronaut surrogate, Centaur could take risks unacceptable to humans, respond more quickly to EVA emergencies and work much longer shifts. Though originally conceived as a system for planetary surface exploration, the Centaur concept could easily be adapted for terrestrial military applications such as de-mining, surveillance and other hazardous duties.
As our robots develop greater range, autonomy, and sensor payloads, the desire to more fully interact with the environment has led researchers to the obvious integration of manipulators on their machines. This paper explores the integration of locomotion and manipulation in diverse forms, defining and then testing seven general design rules. The kinematics study reports on system level choices for integrating limbs on robot bodies, with a critique using metrics that include workspace, strength, occlusion and view factors for perception systems and the relative proportions of the robot to its work site. The design axioms were tested with three cases of radically different mobile robots, spanning the spectrum from gantries, to wheeled vehicles, to free climbers in space. In all cases, the robot design is considered as an anatomical study, comparing relative proportions of the limbs and the robot's body. For the wheeled vehicles in particular, sub categories were considered to identify the impact of multiple arms, and the interplay of manipulation and perception requirements. The study is completed with a look at actual robot prototypes built by the authors in all archetypes, and sub types. The design axioms were tested and found to be both valid and useful as governing principles in each case.
KEYWORDS: Robots, Thermal modeling, Solar energy, Space robots, Control systems, Systems modeling, Sensors, Space operations, Servomechanisms, Capacitance
The extreme environmental conditions of low Earth orbit impact the design and control of space manipulators, requiring solutions not found in terrestrial applications. Among these conditions are the thermal and vacuum states of low Earth orbit, which are considered here. System models are offered to track thermal state as various internal and external heat transfer mechanisms act on the system. Sensory requirements for thermal management are proposed, with applications described for on line control and off line trajectory design.
Monolithic robots are poorly suited to the broad requirements and uncertainties of space automation applications. Weight limitations prohibit the selection of many robots, each capable of a few tasks. Building one generic robot limits automation to that robot's narrow application spectrum. A better approach is to fly a set of standardized components that can be reconfigured as required by the immediate needs on the Space Station, the Lunar surface, or beyond. This set of modular building blocks will weigh less than the family of equivalent monolithic machines, offer changeouts of broken components, and widen the spectrum of tasks that automation can address in space. Further advantages of the modular design philosophy include reduced mean time to repair, reduced operator training, and reduced system cost. While a number of robotic joint and link modules have been developed within the community (7 joints and 12 links at UT alone) there has yet to be an agreement on the standardized interfaces that other industries have exploited. The goal for this project was to design a modular robot standard that allows advanced controllers to communicate with each of the modules, verifying their positions and mounting orientations within the robot, while simultaneously offering a quick release capability to the operator. Two new link modules and one new joint module were designed to support this standard, and their development is reported. The design has proven merits which include a lightweight, high stiffness, on-module data storage, extra wire capacity, and assembly verification capabilities that are unique.
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