5,617 research outputs found
Motion Planning and Posture Control of Multiple n-link Doubly Nonholonomic Manipulators
The paper considers the problem of motion planning and posture control of multiple n-link doubly
nonholonomic mobile manipulators in an obstacle-cluttered and bounded workspace. The workspace
is constrained with the existence of an arbitrary number of fixed obstacles (disks, rods and curves),
artificial obstacles and moving obstacles. The coordination of multiple n-link doubly nonholonomic
mobile manipulators subjected to such constraints becomes therefore a challenging navigational
and steering problem that few papers have considered in the past. Our approach to developing
the controllers, which are novel decentralized nonlinear acceleration controllers, is based on a
Lyapunov control scheme that is not only intuitively understandable but also allows simple but
rigorous development of the controllers. Via the scheme, we showed that the avoidance of all types
of obstacles was possible, that the manipulators could reach a neighborhood of their goal and that
their final orientation approximated the desired orientation. Computer simulations illustrate these
results.
KEYWORDS: Lyapunov-based control scheme; Doubly nonholonomic manipulators; Ghost parking
bays; Minimum distance technique; Stability; Kinodynamic constraints
Coordination of multiple mobile manipulators for ordered sorting of cluttered objects
We present a coordination method for multiple mobile manipulators to sort
objects in clutter. We consider the object rearrangement problem in which the
objects must be sorted into different groups in a particular order. In clutter,
the order constraints could not be easily satisfied since some objects occlude
other objects so the occluded ones are not directly accessible to the robots.
Those objects occluding others need to be moved more than once to make the
occluded objects accessible. Such rearrangement problems fall into the class of
nonmonotone rearrangement problems which are computationally intractable. While
the nonmonotone problems with order constraints are harder, involving with
multiple robots requires another computation for task allocation. The proposed
method first finds a sequence of objects to be sorted using a search such that
the order constraint in each group is satisfied. The search can solve
nonmonotone instances that require temporal relocation of some objects to
access the next object to be sorted. Once a complete sorting sequence is found,
the objects in the sequence are assigned to multiple mobile manipulators using
a greedy allocation method. We develop four versions of the method with
different search strategies. In the experiments, we show that our method can
find a sorting sequence quickly (e.g., 4.6 sec with 20 objects sorted into five
groups) even though the solved instances include hard nonmonotone ones. The
extensive tests and the experiments in simulation show the ability of the
method to solve the real-world sorting problem using multiple mobile
manipulators.Comment: Presented at iROS 202
Research and development at ORNL/CESAR towards cooperating robotic systems for hazardous environments
One of the frontiers in intelligent machine research is the understanding of how constructive cooperation among multiple autonomous agents can be effected. The effort at the Center for Engineering Systems Advanced Research (CESAR) at the Oak Ridge National Laboratory (ORNL) focuses on two problem areas: (1) cooperation by multiple mobile robots in dynamic, incompletely known environments; and (2) cooperating robotic manipulators. Particular emphasis is placed on experimental evaluation of research and developments using the CESAR robot system testbeds, including three mobile robots, and a seven-axis, kinematically redundant mobile manipulator. This paper summarizes initial results of research addressing the decoupling of position and force control for two manipulators holding a common object, and the path planning for multiple robots in a common workspace
Pose consensus based on dual quaternion algebra with application to decentralized formation control of mobile manipulators
This paper presents a solution based on dual quaternion algebra to the
general problem of pose (i.e., position and orientation) consensus for systems
composed of multiple rigid-bodies. The dual quaternion algebra is used to model
the agents' poses and also in the distributed control laws, making the proposed
technique easily applicable to time-varying formation control of general
robotic systems. The proposed pose consensus protocol has guaranteed
convergence when the interaction among the agents is represented by directed
graphs with directed spanning trees, which is a more general result when
compared to the literature on formation control. In order to illustrate the
proposed pose consensus protocol and its extension to the problem of formation
control, we present a numerical simulation with a large number of free-flying
agents and also an application of cooperative manipulation by using real mobile
manipulators
NASA Center for Intelligent Robotic Systems for Space Exploration
NASA's program for the civilian exploration of space is a challenge to scientists and engineers to help maintain and further develop the United States' position of leadership in a focused sphere of space activity. Such an ambitious plan requires the contribution and further development of many scientific and technological fields. One research area essential for the success of these space exploration programs is Intelligent Robotic Systems. These systems represent a class of autonomous and semi-autonomous machines that can perform human-like functions with or without human interaction. They are fundamental for activities too hazardous for humans or too distant or complex for remote telemanipulation. To meet this challenge, Rensselaer Polytechnic Institute (RPI) has established an Engineering Research Center for Intelligent Robotic Systems for Space Exploration (CIRSSE). The Center was created with a five year $5.5 million grant from NASA submitted by a team of the Robotics and Automation Laboratories. The Robotics and Automation Laboratories of RPI are the result of the merger of the Robotics and Automation Laboratory of the Department of Electrical, Computer, and Systems Engineering (ECSE) and the Research Laboratory for Kinematics and Robotic Mechanisms of the Department of Mechanical Engineering, Aeronautical Engineering, and Mechanics (ME,AE,&M), in 1987. This report is an examination of the activities that are centered at CIRSSE
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