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 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

Collaborated a Two-Master-Slave Manipulator Arm with Force Reflection for Defined Miniature Tasks

2013 ◽  
Vol 415 ◽  
pp. 166-173 ◽  
Author(s):  
Nuttapong Nuchprayool ◽  
Viboon Sangveraphunsiri
Keyword(s):  
Dynamic Model ◽  
Pid Controller ◽  
High Speed ◽  
Experimental Result ◽  
Gravity Compensation ◽  
Turn On ◽  
Working Space ◽  
Virtual Fixture ◽  
Manipulator Arm ◽  
Force Reflection

This paper presents the development of a two-master-slave manipulator arm with force reflection for miniature tasks operation. The configuration of the two-master-slave arm is shown and the dynamic model of the slave arm is analyzed. The PID controller with the gravity compensation is selected for controlling desired positions of slave-tool-tips. The movements of the slave arm can be specified with coarse and fine motion. For the coarse motion, the slave arm will be moved approach to a specified workspace area with low precision but high speed. For the fine motion, the slave arm will be controlled with low speed so that the operator feels more confident to move the slave arm, through the master arm, with higher precision within the specified workspace. While operating the manipulator system, the operator can turn on/off the virtual fixture to command force reflection at the master arm for preventing a collision between the slave arm and the obstacles inside the specified working space. The experimental result is shown that the manipulator system is able to be used in miniature tasks operation with 1 millimeter precision.

scholarly journals Kinematic Synthesis of Spatial Serial Chains Using Clifford Algebra Exponentials

2006 ◽  
Vol 220 (7) ◽  
pp. 953-968 ◽  
Author(s):  
A Perez-Gracia ◽  
J M McCarthy
Keyword(s):  
Clifford Algebra ◽  
Robotic System ◽  
Exponential Form ◽  
Kinematic Synthesis ◽  
End Effector ◽  
Dual Quaternions ◽  
Serial Chain ◽  
Joint Parameters ◽  
Position And Orientation ◽  
Serial Chains

This article presents a formulation of the design equations for a spatial serial chain that uses the Clifford algebra exponential form of its kinematics equations. This is the even Clifford algebra C+( P3), known as dual quaternions. These equations define the position and orientation of the end effector in terms of rotations or translations about or along the joint axes of the chain. Because the coordinates of these axes appear explicitly, specifying a set of task positions these equations can be solved to determine the location of the joints. At the same time, joint parameters or certain dimensions are specified to ensure that the resulting robotic system has specific features.

An Articulated Body Algorithm for Modelling and Simulation of an Underwater Vehicle Equipped With Manipulator Arm

2003 ◽  
Author(s):  
A. Meghdari ◽  
G. R. Vossoughi ◽  
M. Amir Hosseini
Keyword(s):  
Degrees Of Freedom ◽  
Underwater Vehicle ◽  
Viscous Drag ◽  
Simulation Algorithm ◽  
Underwater Environment ◽  
Manipulator Arm ◽  
Position And Orientation ◽  
Resultant Forces ◽  
Efficient Dynamic Simulation ◽  
Mobile Base

In this paper, an efficient dynamic simulation algorithm is developed for an Unmanned Underwater Vehicle (UUV) with a N degrees of freedom manipulator. In addition to the effects of mobile base, the various hydrodynamic forces exerted on these systems in an underwater environment are also incorporated into the simulation. The effects modeled in this work are added mass, viscous drag, fluid acceleration, and buoyancy forces. Also the dynamics of thrusters are developed, and an appropriate mapping matrix dependent on the position and orientation of the thrusters on the vehicle, is used to calculate resultant forces and moments of the thrusters on the center of gravity of the vehicle. It should be noted that hull-propeller and propeller-propeller interactions are considered in the modeling too. Finally the results of the simulations are presented.

Workspace and Singularity Characteristics of 3-DOF Planar Parallel Robots

2009 ◽  
Author(s):  
Ming Huang
Keyword(s):  
Computer Simulations ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Geometric Parameters ◽  
Kinematic Structure ◽  
Link Length ◽  
End Effector ◽  
Serial Chain ◽  
Parametric Studies ◽  
Position And Orientation

A study of workspace and singularity characteristics is presented for two common types of 3-DOF planar parallel robot manipulators. The robots considered feature a kinematic structure with 3 in-parallel actuated, R-R-R and R-P-R serial chain geometries. In this study, computer simulations aided with graphic visualization were used to characterize the complete pose workspace (for ranges of both position and orientation) and the singularity inherent to the systems. Parametric studies have also been performed to ascertain the way in which both characteristics vary with respect to various geometric parameters such as pivot location, link length, and platform size for end-effector. Results are shown by way of a unique composite ratio of the available workspace to the density of singularity within that workspace.

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.

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.

Development of a Parallel Manipulator-Based Multifunction Mobility Assistive Device

2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Ahmed Asker ◽  
Samy F. M. Assal
Keyword(s):  
Lower Limb ◽  
Parallel Manipulator ◽  
Upright Position ◽  
Robotic Systems ◽  
Assistive Device ◽  
Finite Element Analyses ◽  
Natural Manner ◽  
Personal Assistance ◽  
Sit To Stand ◽  
Position And Orientation

Abstract Developing robotic systems for reducing the dependence of elderly on personal assistance is one of the most recent hot topics in robotics research. This paper proposes a multifunction mobility assistive device, which consists of an assisting parallel manipulator carried over an active walker. It is developed to interactively assist in various lower limb activities, namely, sit-to-stand, walking, bed or toilet to wheelchair transfer, and support in the upright position. The assisting parallel manipulator is constructed based on two of the nonconventional structure of the 3-RPR parallel manipulator. This structure offers kinematic decoupling between the position and orientation and free of singularity suitable workspace as well as high rigidity and payload capability. Kinematic, dynamic, and finite element analyses are performed to ensure the functionality of the device. A prototype of the device is constructed to verify the applicability of the device. The prototype is shown to be suitable for assisting subjects to stand up in a natural manner.

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