Delayed Position-Feedback Controller for the Reduction of Payload Pendulations of Rotary Cranes

2003 ◽  
Vol 9 (1-2) ◽  
pp. 257-277 ◽  
Author(s):  
Ziyad N. Masoud ◽  
Ali H. Nayfeh ◽  
Amjed Al-Mousa
Keyword(s):  
Control Strategy ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Scaled Model ◽  
Heavy Equipment ◽  
Position Feedback ◽  
Out Of Plane ◽  
Rotary Crane ◽  
Rotational Degrees Of Freedom ◽  
Successful Control

In this paper, we show that, in rotary cranes, it is possible to reduce payload pendulations significantly by controlling the crane's translational and rotational degrees of freedom. Such a control can be achieved with the heavy equipment that is already part of the crane, so that retrofitting existing cranes with such a controller would require little effort. Moreover, the control is superimposed transparently on the commands of the operator. The successful control strategy is based on delayed position feedback of the payload's in-plane and out-of-plane motions. Its effectiveness is demonstrated with a fully nonlinear three-dimensional computer simulation and with an experiment on a scaled model of a rotary crane. The results demonstrate that the pendulations can be significantly reduced, and therefore the rate of operation can be greatly increased. The effectiveness of the controller is demonstrated for both rotary and gantry modes of operation.

Delayed Position-Feedback Controller for the Reduction of Payload Pendulations of Rotary Cranes

2001 ◽  
Author(s):  
Ali H. Nayfeh ◽  
Ziyad N. Masoud
Keyword(s):  
Control Strategy ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Scaled Model ◽  
Heavy Equipment ◽  
Position Feedback ◽  
Out Of Plane ◽  
Rotary Crane ◽  
Rotational Degrees Of Freedom ◽  
Successful Control

Abstract In this work, we show that in rotary cranes, it is possible to reduce payload pendulations significantly by controlling the translational and rotational degrees of freedom of the crane. Such a control can be achieved with the heavy equipment that is already part of the crane so that retrofitting existing cranes with such a controller would require a small effort. Moreover, the control is superimposed on the commands of the operator transparently. The successful control strategy is based on delayed-position feedback of the payload motion in-plane and out-of-plane of the crane. Its effectiveness is demonstrated with a fully nonlinear three-dimensional computer simulation and with an experiment on a scaled model of a rotary crane. The results demonstrate that the pendulations can be significantly reduced, and therefore the operations rate can be greatly increased. The effectiveness of the controller is demonstrated for both rotary and gantry modes of operation of the crane.

scholarly journals Jumping in frogs: assessing the design of the skeletal system by anatomically realistic modeling and forward dynamic simulation

2002 ◽  
Vol 205 (12) ◽  
pp. 1683-1702 ◽  
Author(s):  
William J. Kargo ◽  
Frank Nelson ◽  
Lawrence C. Rome
Keyword(s):  
Degrees Of Freedom ◽  
The Body ◽  
Joint Torque ◽  
Rotational Degree ◽  
Skeletal System ◽  
Dynamic Simulations ◽  
Inverse Dynamic ◽  
Maximal Distance ◽  
Out Of Plane ◽  
Rotational Degrees Of Freedom

SUMMARY Comparative musculoskeletal modeling represents a tool to understand better how motor system parameters are fine-tuned for specific behaviors. Frog jumping is a behavior in which the physical properties of the body and musculotendon actuators may have evolved specifically to extend the limits of performance. Little is known about how the joints of the frog contribute to and limit jumping performance. To address these issues, we developed a skeletal model of the frog Rana pipiens that contained realistic bones, joints and body-segment properties. We performed forward dynamic simulations of jumping to determine the minimal number of joint degrees of freedom required to produce maximal-distance jumps and to produce jumps of varied take-off angles. The forward dynamics of the models was driven with joint torque patterns determined from inverse dynamic analysis of jumping in experimental frogs. When the joints were constrained to rotate in the extension—flexion plane, the simulations produced short jumps with a fixed angle of take-off. We found that, to produce maximal-distance jumping,the skeletal system of the frog must minimally include a gimbal joint at the hip (three rotational degrees of freedom), a universal Hooke's joint at the knee (two rotational degrees of freedom) and pin joints at the ankle,tarsometatarsal, metatarsophalangeal and iliosacral joints (one rotational degree of freedom). One of the knee degrees of freedom represented a unique kinematic mechanism (internal rotation about the long axis of the tibiofibula)and played a crucial role in bringing the feet under the body so that maximal jump distances could be attained. Finally, the out-of-plane degrees of freedom were found to be essential to enable the frog to alter the angle of take-off and thereby permit flexible neuromotor control. The results of this study form a foundation upon which additional model subsystems (e.g. musculotendon and neural) can be added to test the integrative action of the neuromusculoskeletal system during frog jumping.

scholarly journals A comparison of three-dimensional rotation formalisms for least-squares and Bayesian inverse kinematics

2021 ◽  
Author(s):  
Ben Serrien ◽  
Klevis Aliaj ◽  
Todd Pataky
Keyword(s):  
Least Squares ◽  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Estimation Error ◽  
Computational Cost ◽  
Three Dimensional ◽  
Linear Least Squares ◽  
Computationally Efficient ◽  
Rotational Degrees Of Freedom ◽  
Value Decomposition

Marker-based inverse kinematics (IK) is prone to errors arising from measurementnoise and soft-tissue artefacts. Various least-squares and Bayesian methods canbe applied to limit the estimation error to a minimum. Recently proposed meth-ods like Bayesian IK come at an increased computational cost however. In thistechnical paper, we present an overview of eight different least squares or BayesianIK methods, including their accuracy and computational load for IK problemsinvolving a single rigid body and three rotational degrees-of-freedom, whose at-titude is estimated from four noisy marker positions. The results indicate thatNon-Linear Least Squares, Variational Bayesian and full Bayesian IK are supe-rior to Singular Value Decomposition in terms of accuracy, with approximatelya two-fold error reduction. However, only Non-Linear Least Squares and Varia-tional Bayesian IK are computationally efficient enough to scale towards practicaluse in biomechanical applications, with computational durations of 1-10 ms; fullyBayesian procedures required approximately 30 s for single rotation calculations.All Python code and supplementary material can be found in this paper’s GitHubrepository: https://github.com/benserrien/pybik.

A Four-Node Tetrahedral Finite Element Based on Space Fiber Rotation Concept

2019 ◽  
Vol 11 (1) ◽  
pp. 67-78
Author(s):  
Kamel Meftah ◽  
Lakhdar Sedira
Keyword(s):  
Finite Element ◽  
Strain Field ◽  
Stiffness Matrix ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Field Tensor ◽  
Tetrahedral Element ◽  
Numerical Studies ◽  
Rotational Degrees Of Freedom ◽  
Tensor Approximation

Abstract The paper presents a four-node tetrahedral solid finite element SFR4 with rotational degrees of freedom (DOFs) based on the Space Fiber Rotation (SFR) concept for modeling three-dimensional solid structures. This SFR concept is based on the idea that a 3D virtual fiber, after a spatial rotation, introduces an enhancement of the strain field tensor approximation. Full numerical integration is used to evaluate the element stiffness matrix. To demonstrate the efficiency and accuracy of the developed four-node tetrahedron solid element and to compare its performance with the classical four-node tetrahedral element, extensive numerical studies are presented.

Novel Design and Three-Dimensional Printing of Variable Stiffness Robotic Grippers

2016 ◽  
Vol 8 (6) ◽  
Author(s):  
Yang Yang ◽  
Yonghua Chen ◽  
Ying Wei ◽  
Yingtian Li
Keyword(s):  
3D Printing ◽  
Degrees Of Freedom ◽  
Shape Memory Polymer ◽  
Three Dimensional ◽  
Acrylonitrile Butadiene Styrene ◽  
Variable Stiffness ◽  
Analytical Models ◽  
Printing Process ◽  
Finger Joints ◽  
Rotational Degrees Of Freedom

In this paper, a novel robotic gripper design with variable stiffness is proposed and fabricated using a modified additive manufacturing (hereafter called 3D printing) process. The gripper is composed of two identical robotic fingers and each finger has three rotational degrees-of-freedom as inspired by human fingers. The finger design is composed of two materials: acrylonitrile butadiene styrene (ABS) for the bone segments and shape-memory polymer (SMP) for the finger joints. When the SMP joints are exposed to thermal energy and heated to above their glass transition temperature (Tg), the finger joints exhibit very small stiffness, thus allow easy bending by an external force. When there is no bending force, the finger will restore to its original shape thanks to SMP's shape recovering stress. The finger design is actuated by a pneumatics soft actuator. Fabrication of the proposed robotic finger is made possible by a modified 3D printing process. An analytical model is developed to represent the relationship between the soft actuator's air pressure and the finger's deflection angle. Furthermore, analytical modeling of the finger stiffness modulation is presented. Several experiments are conducted to validate the analytical models.

Dynamic Modelling of Blades Based on a Novel Curved Thin Walled Beam Theory

2018 ◽  
Author(s):  
Juan C. Jauregui ◽  
Diego Cardenas ◽  
Hugo Elizalde ◽  
Oliver Probst
Keyword(s):  
Computer Aided Design ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Dynamic Modelling ◽  
Beam Theory ◽  
General Description ◽  
B Splines ◽  
Out Of Plane ◽  
Thin Walled ◽  
Aided Design

There are several Thin-Walled Beam models for straight beams, but few TWB models consider beams with arbitrary curvatures. Although, a curved beam can be modelled using finite elements, the number of degrees of freedom is too large and a nonlinear dynamic solution is very cumbersome, if not impossible. In this work, a general description of arbitrary three-dimensional curves, based on the Frenet-Serret field frame, is applied to determine the dynamic stresses in wing turbines blades. The dynamic model is developed using the Isogeometric Analysis (IGA) and the in plane and out-of-plane curvature’s gradients are found in an Euler-type formulation, allowing the treatment of cases with highly-curved geometry. An Isogeometrical (IGA) formulation relies on a linear combination of Non-Uniform Rational B-Splines (NURBS) to represent not just the model’s geometry, a standard practice in most Computer-Aided Design (CAD) platforms, but also the unknown solution field of each sought variable. For the unified model hitherto described, these variables are represented by a NURBS curve.

Pendulation Reduction on Small Ship-Mounted Telescopic Cranes

2004 ◽  
Vol 10 (8) ◽  
pp. 1167-1179 ◽  
Author(s):  
Ziyad N. Masoud ◽  
Mohammed F. Daqaq ◽  
Nader A. Nayfeh
Keyword(s):  
Control System ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Working Environment ◽  
Control Technique ◽  
Horizontal Position ◽  
Position Feedback ◽  
Small Ship ◽  
Wave Induced ◽  
Control Challenge

Small ship-mounted telescopic cranes are used to load and unload cargo of limited size and weight. The wave-induced motions of the crane ship can cause large pendulations of the hoisted payload bringing the transfer operations to a complete halt. The small size of such a crane, combined with its limited maneu-verability, compared to the relatively larger motion of the host ship, poses a serious control challenge. In this work, a nonlinear control system is introduced which reduces pendulations on these cranes to the point where the transfer operations do not pose a dangerous working environment. Delayed position-feedback technique is used to reduce the payload pendulations. The presented control system uses the slewing, luffing, and telescopic degrees of freedom of the crane to drive the horizontal position of the boom tip. The saturation problem arising from the limited speed and motion of the crane actuators is another issue addressed by this control technique. To demonstrate the performance of the developed control system, numerical simulations are performed on a nonlinear three-dimensional mathematical model of the telescopic crane mounted on the USNS WATERS. The crane has four degrees of freedom: hoisting, slewing, luffing, and extension of the telescopic boom. In addition to its limited maneuverability, nonlinear hydraulic actuators are used for the luffing and extensional degrees of freedom.

scholarly journals A new meta-module design for efficient reconfiguration of modular robots

2021 ◽  
Author(s):  
Irene Parada ◽  
Vera Sacristán ◽  
Rodrigo I. Silveira
Keyword(s):  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Central Point ◽  
The Other ◽  
Three Dimensions ◽  
Modular Robots ◽  
The Novel ◽  
Modular Robot ◽  
Module Design ◽  
Rotational Degrees Of Freedom

AbstractWe propose a new meta-module design for two important classes of modular robots. The new meta-modules are three-dimensional, robust and compact, improving on the previously proposed ones. One of them applies to so-called edge-hinged modular robot units, such as M-TRAN, SuperBot, SMORES, UBot, PolyBot and CKBot, while the other one applies to so-called central-point-hinged modular robot units, which include Molecubes and Roombots. The new meta-modules use the rotational degrees of freedom of these two types of robot units in order to expand and contract, as to double or halve their length in each of the two directions of its three dimensions, therefore simulating the capabilities of Crystalline and Telecube robots. Furthermore, in the edge-hinged case we prove that the novel meta-module can also perform the scrunch, relax and transfer moves that are necessary in any tunneling-based reconfiguration algorithm for expanding/contracting modular robots such as Crystalline and Telecube. This implies that the use of meta-meta-modules is unnecessary, and that currently existing efficient reconfiguration algorithms can be applied to a much larger set of modular robots than initially intended. We also prove that the size of the new meta-modules is optimal and cannot be further reduced.

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