Emulating Micro-Gravity in Laboratory Studies of Space Robotics

1994 ◽  
Author(s):  
Thomas R. J. Corrigan ◽  
Steven Dubowsky
Keyword(s):  
Experimental Test ◽  
Robotic Systems ◽  
Gravity Compensation ◽  
Space Robotics ◽  
Laboratory Studies ◽  
Space Manipulator ◽  
Supporting Structure ◽  
Dynamic Forces ◽  
Spatial System ◽  
Micro Gravity

Abstract Experimentally evaluating micro-gravity control and planning algorithms for space robotic systems on earth is difficult because gravity masks the more subtle dynamic forces which dominate in space. Previous experimental test beds for micro-gravity have been largely restricted to planar motion, or have other limitations. Recently developed is a fully spatial system called the VES which overcomes many of these problems. However, compensating for the effects of gravity with the VES is a challenge. Here, two methods of gravity compensation are presented which allow fully spatial emulation of the micro-gravity interaction between a space manipulator and its supporting structure or spacecraft. Experimental results show the effectiveness of the methods.

Modular Advantage and Kinematic Decoupling in Gravity Compensated Robotic Systems

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
Nick Eckenstein ◽  
Mark Yim
Keyword(s):  
Vertical Plane ◽  
Robotic Systems ◽  
Gravity Compensation ◽  
Pulley System ◽  
Free Length ◽  
Low Profile ◽  
Serial Chain ◽  
Manipulator Arm ◽  
Spring Method ◽  
Position And Orientation

Two new designs for gravity compensated modular robotic systems are presented and analyzed. The gravity compensation relies on using zero-free-length springs approximated by a cable and pulley system. Simple yet powerful parallel four-bar modules enable the low-profile self-contained modules with sequential gravity compensation using the spring method for motion in a vertical plane. A second module that is formed as a parallel six-bar mechanism adds a horizontal motion to the previous system that also yields a complete decoupling of position and orientation of the distal end of a serial chain. Additionally, we introduce the concept of vanishing effort where as the number of modules that comprise an articulated serial chain increases, the actuation authority required at any joint reduces. Essentially, this results in a method for distributing actuation along the length of an articulated chain. Prototypes were designed and constructed validating the analysis and accomplishing the functions of a general serial-type manipulator arm.

scholarly journals Ultrafine Particle and Fiber Production in Micro-Gravity

1986 ◽  
Vol 87 ◽  
Author(s):  
George W. Webb
Keyword(s):  
Experimental Test ◽  
Ultrafine Particles ◽  
Ultrafine Particle ◽  
Inert Gas ◽  
Reduced Gravity ◽  
Fiber Production ◽  
Evaporation And Condensation ◽  
Gravity Driven ◽  
Micro Gravity

AbstractWe have investigated the technique of evaporation and condensation of material in an inert gas (ECIIG) for the purpose of preparing ultrafine particles (of order 10 nm in diameter) with a narrow distribution of sizes. Gravity driven convection increases the rate of coalescence of the particles leading to larger sizes and a broader distribution. Here we report on analysis and experiments to investigate coalescence of particles. The possibility of reducing coalescence in micro-gravity is discussed. An experimental test in reduced gravity to be performed in a KC135 aircraft is described briefly.

scholarly journals An output-feedback global continuous control scheme with desired gravity compensation for the finite-time and exponential regulation of bounded-input robotic systems

2018 ◽  
Vol 51 (22) ◽  
pp. 108-114 ◽  
Author(s):  
Griselda I. Zamora-Gómez ◽  
Arturo Zavala-Río ◽  
Daniela J. López-Araujo ◽  
Emmanuel Nuño ◽  
Emmanuel Cruz-Zavala
Keyword(s):  
Output Feedback ◽  
Finite Time ◽  
Robotic Systems ◽  
Continuous Control ◽  
Gravity Compensation ◽  
Control Scheme ◽  
Bounded Input

Massively Parallel Granular Media Modeling of Robot-Terrain Interactions

2012 ◽  
Author(s):  
Rudranarayan M. Mukherjee ◽  
Ryan Houlihan
Keyword(s):  
Force Field ◽  
Granular Media ◽  
Robotic Systems ◽  
Massively Parallel ◽  
Discrete Element Modeling ◽  
Damping Force ◽  
Computing Systems ◽  
Massively Parallel Computing ◽  
Micro Gravity ◽  
Robotic Tools

This paper presents select results that demonstrate the feasibility of modeling the interactions of robotic systems with granular terrain through Discrete Element Modeling (DEM) using massively parallel computing systems. We report numerical simulation results of full 3D DEM simulations with the granular material modeled as a deformable bed of spherical granules. The mobility systems of the robots retain their CAD geometry and are represented as triangular meshes. The inter-granular interactions and the interactions between the CAD mesh triangles with the granules are modeled explicitly using a deformation-damping force field. The parameters of the force field are derived from physically measurable properties. We model friction, cohesion, and shearing and other interactions among the granules, and between the CAD mesh and the granules. The simulations involve granular beds with number of granules in the order of several hundred thousand to several millions. Temporally, we report simulations in the order of several seconds. These simulations were run on parallel clusters with number of processors ranging from 100 to 256. We present the findings from a number of simulations ranging including wheeled and legged mobility systems, and robotic tools in micro-gravity environments.

scholarly journals “Space Robotics”

2021 ◽  
Keyword(s):  
System Engineering ◽  
Space Science ◽  
Theory And Practice ◽  
Robotic Systems ◽  
Space Robotics ◽  
Series Space ◽  
Chinese Academy Of Sciences ◽  
Institute Of Technology ◽  
Beijing Institute ◽  
Academy Of Sciences

“Space Robotics” by Yaobing Wang belongs to the series Space Science and Technologies co-published by Beijing Institute of Technology Press, China, and Springer Nature Pte Ltd, Singapore. The Editor-in-Chief of the series, Peijian Ye, is Academician of the Chinese Academy of Sciences in Beijing and has published a collection of 10 volumes. This volume’s author, Yaobin Wang, is a research professor of Beijing Institute of Spacecraft System Engineering and Director of Beijing Key Laboratory of Intelligent Space Robotic Systems Technology and Applications. The book’s 363 pages provide a condensed combination of theory and practice as engineering guidance.

Researches on the Behavior of the Supporting Structure of Railway Traction Vehicles under the Effect of Shock Dynamic Forces

2014 ◽  
Vol 659 ◽  
pp. 237-242
Author(s):  
Ioan Sebesan ◽  
Gabriel Popa ◽  
Marius Adrian Spiroiu
Keyword(s):  
Traffic Safety ◽  
Rolling Process ◽  
Railway Vehicle ◽  
Frontal Impact ◽  
Stick Slip ◽  
Driving System ◽  
Supporting Structure ◽  
Longitudinal Dynamic ◽  
Dynamic Forces ◽  
Railway Traction

During circulation the railway vehicle is subjected to the action of dynamic forces under the effect of shocks that appear in the driving system caused by stick slip phenomenon, dynamic forces arising from the rolling process when the wheelset is passing over accidental vertical unevenness of the track and also longitudinal dynamic forces occurring in the case of buffering, respectively those caused by frontal impact (the crash forces). The present paper presents the mechanical and mathematical models which are underlying the evaluation of the magnitude of these forces as well as their effects on the resistance of supporting structure of the vehicle and on traffic safety.

A Compliant Contact Model Including Interference Geometry for Space Robotic Systems

2005 ◽  
Author(s):  
Lianzhen Luo ◽  
Meyer Nahon
Keyword(s):  
Material Properties ◽  
Geometric Parameters ◽  
Contact Dynamics ◽  
Robotic Systems ◽  
Space Robotics ◽  
Dynamics Model ◽  
Geometric Algorithm ◽  
Design Cycle ◽  
Simulation Results ◽  
Object Shapes

Modeling of contact with the environment is an essential capability for the simulation of space robotics system, which includes tasks such as berthing and docking. The effect of interbody contact on the robotics system has to be determined to predict potential problems in the design cycle. A compliant contact dynamics model is proposed here, which considers most possible contact situations for a wide diversity of possible object shapes and using interference geometry information. A uniform formula is provided to determine the contact force as a function of geometric parameters and material properties. A corresponding geometric algorithm is provided in order to obtain the necessary geometric parameters. Some simulation results are presented based on the implementation of the geometric algorithm.

scholarly journals On the Impact of Gravity Compensation on Reinforcement Learning in Goal-Reaching Tasks for Robotic Manipulators

Robotics ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 46
Author(s):  
Jonathan Fugal ◽  
Jihye Bae ◽  
Hasan A. Poonawala
Keyword(s):  
Reinforcement Learning ◽  
Autonomous Systems ◽  
Learning Technologies ◽  
Robotic Systems ◽  
Gravity Compensation ◽  
Reaching Tasks ◽  
Combined Control ◽  
Classical Control ◽  
The Impact ◽  
Target Locations

Advances in machine learning technologies in recent years have facilitated developments in autonomous robotic systems. Designing these autonomous systems typically requires manually specified models of the robotic system and world when using classical control-based strategies, or time consuming and computationally expensive data-driven training when using learning-based strategies. Combination of classical control and learning-based strategies may mitigate both requirements. However, the performance of the combined control system is not obvious given that there are two separate controllers. This paper focuses on one such combination, which uses gravity-compensation together with reinforcement learning (RL). We present a study of the effects of gravity compensation on the performance of two reinforcement learning algorithms when solving reaching tasks using a simulated seven-degree-of-freedom robotic arm. The results of our study demonstrate that gravity compensation coupled with RL can reduce the training required in reaching tasks involving elevated target locations, but not all target locations.

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