Coordinated-motion control of heavy-duty industrial machines with redundancy

Robotica ◽  
1995 ◽  
Vol 13 (6) ◽  
pp. 623-633 ◽  
Author(s):  
N. Singh ◽  
H. Zghal ◽  
N. Sepehri ◽  
S. Balakrishnan ◽  
P. D. Lawrence
Keyword(s):  
Real Time ◽  
Motion Control ◽  
Performance Criterion ◽  
Hyperbolic Function ◽  
Coordinated Motion ◽  
Special Cases ◽  
Joint Limits ◽  
Joint Motions ◽  
Joint Velocity ◽  
New Criterion

SummaryAn implementation of a real-time scheme suitable for coordinated-motion control of a class of teleoperated industrial machines with redundancy is presented. An efficient gradient projection technique is adopted for the numerical solution. The scheme utilizes the redundancy to avoid the joint limits by minimizing a hyperbolic function of the joint distances from the mid-range. This new performance criterion is shown to be advantageous over similar criteria; both the joint-limit avoidance capability and the resulting joint velocity profiles can be adjusted by the appropriate choice of parameters introduced in the criterion. Previous criteria are shown to be special cases of the new criterion. Furthermore, the scheme includes a novel algorithm which incorporates the bounded joint velocities. The joint motions are determined considering both the required task in terms of the desired end-effector speed and the dynamic considerations, such as hydraulic circuit interdependency and power limitations.The feasibility and effectiveness of the implementation of the scheme is first tested through simulations of a Kaiser Spyder-like excavator machine on a PC-486 micro-computer. The robustness and real-time response of the scheme are then validated on a real-time excavator-based graphics simulator interfaced to a human operator through a joystick.

Coordinated Motion Control of Large-Scale Transporter for Conveying Heavy Frame Components in Ship-Manufacturing

2006 ◽  
Vol 505-507 ◽  
pp. 1159-1164
Author(s):  
Yun Hua Li ◽  
Li Man Yang ◽  
Gui Lin Yang
Keyword(s):  
Real Time ◽  
Motion Control ◽  
Large Scale ◽  
Steering System ◽  
Networked Control System ◽  
Dynamics Modeling ◽  
Time Data ◽  
Coordinated Motion ◽  
Modeling And Analysis ◽  
Control Methodology

A large-scale elevating transporter that has multi-wheels to be steered independently is a very complex mechatronic system. Aiming at its real-time coordinated motion control, a multi-mode steering system based on Networked Control System (NCS) is proposed to tackle the problem in the paper. Through motion synthesis, such as kinematics and dynamics modeling and analysis, and using the inherent real-time data sharing of the NCS, a cross-coupled control algorithm for improving contour accuracy is developed. This control methodology is then applied to the coordinated motion control of a practical product with multi-steering modes successfully.

scholarly journals A multi-step Lagrangian scheme for spatially inhomogeneous evolutionary games

2021 ◽  
Author(s):  
Stefano Almi ◽  
Marco Morandotti ◽  
Francesco Solombrino
Keyword(s):  
Mean Field ◽  
Evolutionary Games ◽  
Type Systems ◽  
Convergence Result ◽  
Performance Criterion ◽  
Mean Field Limit ◽  
Spatially Inhomogeneous ◽  
Convergence Results ◽  
Special Cases ◽  
Lagrangian Scheme

AbstractA multi-step Lagrangian scheme at discrete times is proposed for the approximation of a nonlinear continuity equation arising as a mean-field limit of spatially inhomogeneous evolutionary games, describing the evolution of a system of spatially distributed agents with strategies, or labels, whose payoff depends also on the current position of the agents. The scheme is Lagrangian, as it traces the evolution of position and labels along characteristics, and is a multi-step scheme, as it develops on the following two stages: First, the distribution of strategies or labels is updated according to a best performance criterion, and then, this is used by the agents to evolve their position. A general convergence result is provided in the space of probability measures. In the special cases of replicator-type systems and reversible Markov chains, variants of the scheme, where the explicit step in the evolution of the labels is replaced by an implicit one, are also considered and convergence results are provided.

The Practical Wisdom Framework: A Compass for School Leaders

2021 ◽  
pp. 002205742110288
Author(s):  
Karen Elizabeth Bohlin
Keyword(s):  
Real Time ◽  
Practical Wisdom ◽  
School Leaders ◽  
Educational Leaders ◽  
Policy Compliance ◽  
Special Cases

Educational leaders are required to respond in real time to questions, quandaries, and cases that involve individuals in different contexts. They face an array of possible choices that exist in tension. Justice and fairness must coexist with mercy and compassion; in enforcing policy, compliance must make room for flexibility in special cases. School leaders are called to adjudicate competing goods and teach others to do the same. This article examines what practical wisdom is, why it matters, and introduces a theoretically grounded Practical Wisdom Framework (PWF) to help school leaders deliberate well to create and sustain formative institutions.

On-line multi-criteria based collision-free posture generation of redundant manipulator in constrained workspace

Robotica ◽  
2002 ◽  
Vol 20 (6) ◽  
pp. 625-636 ◽  
Author(s):  
Jin-Liang Chen ◽  
Jing-Sin Liu ◽  
Wan-Chi Lee ◽  
Tzu-Chen Liang
Keyword(s):  
Null Space ◽  
Large Degree ◽  
Redundancy Resolution ◽  
Secondary Tasks ◽  
End Effector ◽  
Robotic Arms ◽  
Tracking Motion ◽  
On Line ◽  
Joint Limits ◽  
Joint Velocity

The manipulator with a large degree of redundancy is useful for realizing multiple tasks such as maneuvering the robotic arms in the constrained workspace, e.g. the task of maneuvering the end-effector of the manipulator along a pre-specified path into a window. This paper presents an on-line technique based on a posture generation rule to compute a null-space joint velocity vector in a singularity-robust redundancy resolution method. This rule suggests that the end of each link has to track an implicit trajectory that is indirectly resulted from the constraint imposed on tracking motion of the end-effector. A proper posture can be determined by sequentially optimizing an objective function integrating multiple criteria of the orientation of each link from the end-effector toward the base link as the secondary task for redundancy resolution, by assuming one end of the link is clamped. The criteria flexibly incorporate obstacle avoidance, joint limits, preference of posture in tracking, and connection of posture to realize a compromise between the primary and secondary tasks. Furthermore, computational demanding of the posture is reduced due to the sequential link-by-link computation feature. Simulations show the effectiveness and flexibility of the proposed method in generating proper postures for the collision avoidance and the joint limits as a singularity-robust null-space projection vector in maneuvering redundant robots within constrained workspaces.

scholarly journals Interactive Virtual Humans in Real-Time Virtual Environment

2006 ◽  
Vol 5 (2) ◽  
pp. 15-24 ◽  
Author(s):  
Nadia Magnenat-Thalmann ◽  
Arjan Egges
Keyword(s):  
Real Time ◽  
Linear Representation ◽  
Virtual Humans ◽  
Precise Control ◽  
Ongoing Work ◽  
The Face ◽  
Input Motion ◽  
High Level ◽  
Joint Motions ◽  
Vast Area

In this paper, we will present an overview of existing research in the vast area of IVH systems. We will also present our ongoing work on improving the expressive capabilities of IVHs. Because of the complexity of interaction, a high level of control is required over the face and body motions of the virtual humans. In order to achieve this, current approaches try to generate face and body motions from a high-level description. Although this indeed allows for a precise control over the movement of the virtual human, it is difficult to generate a natural-looking motion from such a high-level description. Another problem that arises when animating IVHs is that motions are not generated all the time. Therefore a flexible animation scheme is required that ensures a natural posture even when no animation is playing. We will present MIRAnim, our animation engine, which uses a combination of motion synthesis from motion capture and a statistical analysis of prerecorded motion clips. As opposed to existing approaches that create new motions with limited flexibility, our model adapts existing motions, by automatically adding dependent joint motions. This renders the animation more natural, but since our model does not impose any conditions on the input motion, it can be linked easily with existing gesture synthesis techniques for IVHs. Because we use a linear representation for joint orientations, blending and interpolation is done very efficiently, resulting in an animation engine especially suitable for real-time applications

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