203 research outputs found
Modelado de Cadenas Cinemáticas mediante Matrices de Desplazamiento. Una alternativa al método de Denavit-Hartenberg
No full textEn este trabajo se presenta un método para el modelado de cadenas cinemáticas de robots que salva las dificultades asociadas a la elección de los sistemas de coordenadas y obtención de los parámetros de Denavit-Hartenberg. El método propuesto parte del conocimiento de la posición y orientación del extremo del robot en su configuración de reposo, para ir obteniendo en qué se transforman éstas tras los sucesivos movimientos de sus grados de libertad en secuencia descendente, desde el más alejado al más cercano a su base. Los movimientos son calculados en base a las Matrices de Desplazamiento, que permiten conocer en que se transforma un punto cuando éste es desplazado (trasladado o rotado) con respecto a un eje que no pasa por el origen. A diferencia del método de Denavit-Hartenberg, que precisa ubicar para cada eslabón el origen y las direcciones de los vectores directores de los sistemas de referencia asociados, el método basado en las Matrices de Desplazamiento precisa solo identificar el eje de cada articulación, lo que le hace más simple e intuitivo que aquel. La obtención de las Matrices de Desplazamiento y con ellas del Modelo Cinemático Directo a partir de los ejes de la articulación, puede hacerse mediante algunas simples operaciones, fácilmente programables
A data-driven kinematic model of the human hand with soft-tissue artifact compensation mechanism for grasp synergy analysis
No full textThis paper presents a methodology to accurately
record human finger postures during grasping. The main
contribution consists of a kinematic model of the human hand
reconstructed via magnetic resonance imaging of one subject
that (i) is fully parameterized and can be adapted to different
subjects, and (ii) is amenable to in-vivo joint angle recordings
via optical tracking of markers attached to the skin. The
principal novelty here is the introduction of a soft-tissue artifact
compensation mechanism that can be optimally calibrated in a
systematic way. The high-quality data gathered are employed
to study the properties of hand postural synergies in humans,
for the sake of ongoing neuro-science investigations. These
data are analyzed and some comparisons with similar studies
are reported. After a meaningful mapping strategy has been
devised, these data could be employed to define robotic hand
postures suitable to attain effective grasps, or could be used as
prior knowledge in lower-dimensional, real-time avatar hand
animation
Comparison between Standard and Modified Denavit-Hartenberg Methods in Robotics Modelling
No full textAbstract -In the present article, the matrix fundamental method of Denavit and Hartenberg standard and modified are faced, after the comparison has been made, it is demonstrated that in boot cases is similar the way how the links and joints are numerated. The links are numerated in ascending order starting from 0 fixed link to n the last thing, in the same way the joints are numerated from 1 going forward, following in the same case the cinematic chain, also the matrices product is used in the same sequence of the movements made for the mobile coordinates systems. The two methods has different forms to assign coordinates systems. In the standard D-H method the origin of the system I is along the axis of the articulation i+1, and the sequence of movements is rotation and translation in Z, after that a translation and rotation along X is made. In the modified D-H method the origin of the systems i is along the joint I, and the sequence of movements is rotation and translation along X and the rotation and translation along Z
A study on forward and inverse kinematics of 6-DOF robot
No full textMulti Degree-of-Freedom (DOF) robots have taken significant roles in the robotization of various industries. They provide significantly more accuracy in performing regular tasks compared to manual work. The robot arms comprise a microcontroller, shoulder, elbow, wrist, and a gripper. Smooth movement in the joints is required for the robot to work with precise and safe operation. An articulated robot was considered for pick and place operations performed in the CoppeliaSim simulator to study the movements. This study provided forward and inverse kinematics calculations, and then simulations were performed to analyze the movements in joints according to time.
The transformation matrices were calculated using the Denavit-Hartenberg convention, and the parameters of Denavit-Hartenberg were assigned according to the robot's kinematic model. Forward kinematics was derived, which was the final transformation matrix, and Inverse kinematics was derived for a given position and orientation of the robot. The third-order cubic polynomial with intermediate points method was used for trajectory. The simulations were performed in CoppeliaSim software with Lua Programming Language, and simulation data was saved as a .csv file for the position, velocity, and accelerations plot analysis
The thumb: Guidelines for a robotic design
No full textThe impressive manipulation capabilities of the human hand are undoubtedly related to the thumb opposition. Such a versatility is highly desirable in the context of humanoid robots, in particular when performing object manipulation. Biomechanical data, surgery procedures and rehabilitation surveys represent an excellent base from which a robotic design can be inferred. This knowledge must be understood to identify the properties required for manipulation skills, and especially, to obtain a holistic view of the thumb functionality. Several designs have been realized, that concentrated on biomimetism or on classical mechanism designs. Therefore, it is currently difficult for designers to obtain a clear overview of the properties required for a functional robot thumb. In the present case, a robotic hand with size, forces, velocity and shape comparable to the human ones, is envisioned. Unlike most of robotic designs - where the fingers are modular and the thumb is simply a finger placed in opposition — the thumb benefits from an intensive functional analysis. This paper gathers anatomy, surgery and rehabilitation data and identifies the properties required for human like manipulation. Based on this synergy, guidelines are presented that are fused and applied to the hand design of the Integrated Hand arm project of DLR
Precision Denavit–Hartenberg Parameter Calibration for Industrial Robots Using a Laser Tracker System and Intelligent Optimization Approaches
No full textPrecision object handling and manipulation require the accurate positioning of industrial robots. A common practice for performing end effector positioning is to read joint angles and use industrial robot forward kinematics (FKs). However, industrial robot FKs rely on the robot Denavit–Hartenberg (DH) parameter values, which include uncertainties. Sources of uncertainty associated with industrial robot FKs include mechanical wear, manufacturing and assembly tolerances, and robot calibration errors. It is therefore necessary to increase the accuracy of DH parameter values to reduce the impact of uncertainties on industrial robot FKs. In this paper, we use differential evolution, particle swarm optimization, an artificial bee colony, and a gravitational search algorithm to calibrate industrial robot DH parameters. A laser tracker system, Leica AT960-MR, is utilized to register accurate positional measurements. The nominal accuracy of this non-contact metrology equipment is less than 3 μm/m. Metaheuristic optimization approaches such as differential evolution, particle swarm optimization, an artificial bee colony and a gravitational search algorithm are used as optimization methods to perform the calibration using laser tracker position data. It is observed that, using the proposed approach with an artificial bee colony optimization algorithm, the accuracy of industrial robot FKs in terms of mean absolute errors of static and near-static motion over all three dimensions for the test data decreases from its measured value of 75.4 μm to 60.1 μm (a 20.3% improvement)
Modeling, electrical and software development of construction mobile manipulator (Part II)
No full textThis report presents the Final Year Project undertaken by the author over a period of one year in School of Mechanical and Aerospace Engineering. In this report, the author will be covering on the modeling process for the construction mobile manipulator and also the electrical and software development of the scale down model. In the modeling process chapter, the author will be using Denavit-Hartenberg method to model the parameters of both the designed and scale down robotic arm.Bachelor of Engineering (Mechanical Engineering
Kinematics Modeling of the Amigobot Robot
No full textIn this article authors presenting problems connected with the kinematics modeling based on Denavit-Hartenberg notation for a wheeled mobile robot. The possibility of sending data between Maple T M and Matlab T M has been discussed. Simulations of the kinematics parameters have been made and the results are shown
Characterization of behavior of steel-concrete composite members and frames with applications for design
No full textSteel-concrete composite frames are seeing increased use in practice. Their excellent structural characteristics, including high strength, stiffness, and ductility, make them an appealing option for many building configurations. However, there exist gaps in the knowledge of behavior and the design provisions for these structures. This work seeks to document composite member and frame behavior and address key design issues through targeted studies utilizing advanced computational formulations and detailed examination of experimental results.
A three-dimensional distributed plasticity beam finite element formulation suitable for nonlinear static and dynamic analyses of steel-concrete composite frames has been developed. The formulation is suitable for both concrete-filled steel tubes (CFT) and steel reinforced concrete (SRC) members, as well as steel wide-flange and hollow structural steel sections that are part of composite frames. A mixed basis for the formulation was chosen to allow for accurate modeling of both material and geometric nonlinearities. The formulation utilizes uniaxial cyclic constitutive relations for the concrete and steel that account for the salient features of each material, as well as the interaction between the two, including concrete confinement and local buckling. The accuracy of the formulation was verified against a wide variety of monotonic and cyclic experimental results of composite members, demonstrating the capability of the formulation to accurately produce realistic simulations of element and frame behavior.
Aspects of the behavior of composite columns were assessed through an examination of results from a series of experiments on full-scale slender CFT beam-columns conducted by project collaborators. Additionally, comparative computational analyses were performed using the mixed beam formulation and detailed data interpretation focusing on the beam-column interaction strength was conducted.
Several aspects of the design of steel-concrete composite structures were examined. The natural bond behavior of CFT columns was investigated through an examination of prior experimental work and new provisions were developed for the assessment of natural bond strength of CFT connections. The in-plane stability behavior of steel-concrete composite members and frames was assessed through a parametric study on small non-redundant benchmark frames, leading to the development of new elastic flexural rigidities for elastic analysis of composite members; new effective flexural rigidities for calculating the axial compressive strength of SRC members; new Direct Analysis stiffness reductions for composite members; and new recommendations for the construction of the interaction diagram for composite members.
The seismic behavior of composite moment and braced frames was assessed through static pushover and incremental dynamic analyses. The analyses were performed on a suite of 60 archetype frames that were designed according to current design provisions. Connections were assumed to be strong; however, panel zone behavior for the moment frames and bond-slip behavior for SRC columns were included in the model. Using the analysis results, system performance factors were developed for the composite frames based on the methodology described in FEMA P695.Item withdrawn by Mark Zulauf ([email protected]) on 2012-12-03T17:04:10Z
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University of Illinois Theses & Dissertations (ID: 1)
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