Robotics Technology for Planetary Missions into the 21st Century
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Engineering topics
Publications and source records attributed to Rodriguez, G..
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A telerobotic platform developed in a collaboration between NASA-JPL and MicroDexterity Systems, Inc (MDS) is described in this paper.
Describes the technological developments which are establishing the foundation for an exciting era of in situ exploration missions to planets, comets and asteroids with advanced robotic systems. Also outlines important concurrent terrestrial applications and spinoffs of the space robotics technology. These include high-precision robotic manipulators for microsurgical operations and dexterous arm control systems.
Provided is an overview of emerging technologies in miniaturized roving vehicles that enable new types of low-cost planetary missions, those which are aimed at detailed survey of extended surface areas, collection and analysis of interesting samples, and in-situ analysis of scientific data. New types of planetary surface data can be acquired at low-cost through the use of innovative technologies.
Exploration of Mars is a major thrust of NASA. Some of the important goals of this exploration are (1) the search for life and understanding of evolution of the planet, (2) the discovery of accessible water, (3) understanding how the climate has changed, and (4) developing an inventory of useful resources, as a precursor to human exploration.
Planetary aerobots are described. They are a new type of lightweight and low-cost telerobot that use phase change fluids to ascend and descend, thus allowing data acquisition from multiple sites. Potential near-term missions discussed include those to Venus, Mars, and Titan. Similarities are discussed for missions in the Earth atmosphere and deep sea.
The goal of our program is to develop, integrate and demonstrate the science and technology of remote telerobotics leading to increases in operational capability, safety, cost effectiveness and probability of success of NASA missions. To that end, the program fosters the development of innovative system concepts for on-orbit servicing and planetary surface missions which use telerobotic systems as an important central component. These concepts are carried forward into develoments which are used to evaluate and demonstrate technology in realistic flight and ground experiments.
This paper presents and overview of the telerobotic research and development activities underway at the Jet Propulsion Laboratory in support of NASA thrusts in telerobotic servicing of free flying satellites and platforms, planetary exploration, and dual use technologies enhancing both NASA ground applications and commercial competitiveness.
Complex missions require routine and unscheduled inspection for safe operation. The purpose of research in this task is to facilitate structural inspection of the planned Space Station while mitigating the need for extravehicular activity (EVA), and giving the operator supervisory control over detailed and somewhat mundane, but important tasks. The telerobotic system enables inspection relative to a given reference (e.g., the status of the facility at the time of the last inspection) and alerts the operator to potential anomalies for verification and action. There are two primary objectives of this project: (1) To develop technologies that enable well-integrated NASA ground-to-orbit telerobotics operations, and (2) to develop a prototype common architecture workstation which implements these capabilities for other NASA technology projects and planned NASA flight applications. This task develops and supports three telerobot control modes which are applicable to time delay operation: Preview teleoperation, teleprogramming, and supervised autonomy.
This paper develops methods for noninteracting control of articulated, possibly flexible, multibody space vehicles based on the diagonalized equation of motion.
A diagonal equation for robot dynamics is developed by combining recent mass matrix factorization results with classical Lagrangian mechanics.
The present recursive algorithm for solving molecular systems' dynamical equations of motion employs internal variable models that reduce such simulations' computation time by an order of magnitude, relative to Cartesian models. Extensive use is made of spatial operator methods recently developed for analysis and simulation of the dynamics of multibody systems. A factor-of-450 speedup over the conventional O(N-cubed) algorithm is demonstrated for the case of a polypeptide molecule with 400 residues.
This paper presents an approach to modeling the dynamics of flexible multibody systems such as flexible spacecraft and limber space robotic systems. A large number of degrees of freedom and complex dynamic interactions are typical in these systems. This paper uses spatial operators to develop efficient recursive algorithms for the dynamics of these systems. This approach very efficiently manages complexity by means of a hierarchy of mathematical operations.
The U.S. Army is currently spending 300 million dollars per year replacing rubber track pads. An experimental rubber compound has been developed which exhibits 2 to 3 times greater service life than standard production pad compounds. To improve the service life of the tank track pads various aspects of rubber chemistry were explored including polymer, curing and reinforcing systems. Compounds that exhibited superior physical properties based on laboratory data were then fabricated into tank pads and field tested. This paper will discuss the compounding studies, laboratory data and field testing that led to the high wear elastomer compound.
Linearized dynamics models for manipulators are useful in robot analysis, motion planning, and control applications. Techniques from the spatial operator algebra are used to obtain closed form operator expressions for two types of linearized dynamics models, the linearized inverse and forward dynamics models. Spatially recursive algorithms of O(n) and O(n-squared) complexity for the computation of the perturbation vector and coefficient matrices for the linearized inverse dynamics model are developed first. Subsequently, operator factorization and inversion identities are used to develop corresponding closed-form expressions for the linearized forward dynamics model (LFDM). Once again, these are used to develop algorithms of O(n) and O(n-squared) complexity for the computation of the perturbation vector and the coefficient matrices. The algorithms for the LFDM do not require the explicit computation of the mass matrix nor its numerical inversion and are also of lower complexity than the conventional O(n-cubed) algorithms.
This paper uses spatial operators to develop new spatially recursive dynamics algorithms for flexible multibody systems. The operator description of the dynamics is identical to that for rigid multibody systems. Assumed-mode models are used for the deformation of each individual body. The algorithms are based on two spatial operator factorizations of the system mass matrix. The first (Newton-Euler) factorization of the mass matrix leads to recursive algorithms for the inverse dynamics, mass matrix evaluation, and composite-body forward dynamics for the systems. The second (innovations) factorization of the mass matrix, leads to an operator expression for the mass matrix inverse and to a recursive articulated-body forward dynamics algorithm. The primary focus is on serial chains, but extensions to general topologies are also described. A comparison of computational costs shows that the articulated-body, forward dynamics algorithm is much more efficient than the composite-body algorithm for most flexible multibody systems.
A recently developed spatial operator algebra approach to modeling and analysis of multibody robotic systems is used to develop O(n) recursive algorithms that compute the operational space mass matrix and the operational space coriolis/centrifugal and gravity terms of an n-link serial manipulator. These algorithms enable an O(n) recursive implementation of operational space control.
The Spatial Operator Algebra framework for the dynamics of general multibody systems is described. The use of a spatial operator-based methodology permits the formulation of the dynamical equations of motion of multibody systems in a concise and systematic way. The dynamical equations of progressively more complex grid multibody systems are developed in an evolutionary manner beginning with a serial chain system, followed by a tree topology system and finally, systems with arbitrary closed loops. Operator factorizations and identities are used to develop novel recursive algorithms for the forward dynamics of systems with closed loops. Extensions required to deal with flexible elements are also discussed.