scholarly journals Modeling, Design, and Implementation of an Underactuated Gripper with Capability of Grasping Thin Objects

Machines ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 347
Author(s):  
Long Kang ◽  
Sang-Hwa Kim ◽  
Byung-Ju Yi
Keyword(s):  
Lower Cost ◽  
Point Contact ◽  
Torsion Spring ◽  
Passive Joint ◽  
Design And Implementation ◽  
Different Types ◽  
Dynamic Simulator ◽  
Multi Body ◽  
Body Dynamic ◽  
Underactuated Finger

Underactuated robotic grippers have the advantage of lower cost, simpler control, and higher safety over the fully actuated grippers. In this study, an underactuated robotic finger is presented. The design issues that should be considered for stable grasping are discussed in detail. This robotic finger is applied to design a two-fingered underactuated gripper. Firstly, a new three-DOF linkage-driven robotic finger that combines a five-bar mechanism and a double parallelogram is presented. This special architecture allows us to put all of the required actuators into the palm. By adding a torsion spring and a mechanical stopper at a passive joint, this underactuated finger mechanism can be used to perform parallel grasping, shape-adaptive grasping, and environmental contact-based grasp. Secondly, the dynamic model of this robotic finger is developed to investigate how to select an appropriate torsion spring. The dynamic simulation is performed with a multi-body dynamic simulator to verify our proposed approach. Moreover, static grasp models of both two-point and three-point contact grasps are investigated. Finally, different types of grasping modes are verified experimentally with a two-fingered underactuated robotic gripper.

Design and Analysis of a Robotic Modular Leg Mechanism

2016 ◽  
Author(s):  
Wael Saab ◽  
Pinhas Ben-Tzvi
Keyword(s):  
Body Height ◽  
Point Contact ◽  
Dynamic Simulations ◽  
Uneven Terrain ◽  
Quadruped Robots ◽  
System A ◽  
Passive Suspension System ◽  
And Performance ◽  
Multi Body ◽  
Body Dynamic

This paper presents the design and analysis of a reduced degree-of-freedom Robotic Modular Leg (RML) mechanism used to construct a quadruped robot. This mechanism enables the robot to perform forward and steering locomotion with fewer actuators than conventional quadruped robots. The RML is composed of a double four-bar mechanism that maintains foot orientation parallel to the base and decouples actuation for simplified control, reduced weight and lower cost of the overall robotic system. A passive suspension system in the foot enables a stable four-point contact support polygon on uneven terrain. Foot trajectories are generated and synchronized using a trot and modified creeping gait to maintain a constant robot body height, horizontal body orientation, and provide the ability to move forward and steer. The locomotion principle and performance of the mechanism are analyzed using multi-body dynamic simulations of a virtual quadruped and experimental results of an integrated RML prototype.

scholarly journals Virtual Loom: a tool for the interactive 3D representation of historical fabrics

2021 ◽  
Author(s):  
Cristina Portalés ◽  
Manolo Pérez ◽  
Pablo Casanova-Salas ◽  
Jesús Gimeno
Keyword(s):  
Art History ◽  
3D Modelling ◽  
Current Version ◽  
Close Collaboration ◽  
Design And Implementation ◽  
Different Types ◽  
Interactive 3D ◽  
Silk Fabrics ◽  
Definition Of ◽  
3D Representations

Abstract3D modelling of man-made objects is widely used in the cultural heritage sector, among others. It is relevant for its documentation, dissemination and preservation. Related to historical fabrics, weaves and weaving techniques are still mostly represented in forms of 2D graphics and textual descriptions. However, complex geometries are difficult to represent in such forms, hindering the way this legacy is transmitted to new generations. In this paper, we present the design and implementation of SILKNOW’s Virtual Loom, an interactive tool aimed to document, preserve and represent in interactive 3D forms historical weaves and weaving techniques of silk fabrics, dating from the 15th to the 19th centuries. To that end, our tool only requires an image of a historical fabric. Departing from this image, the tool automatically subtracts the design, and allows the user to apply different weaves and weaving techniques. In its current version, the tool embeds five traditional weaving techniques, 39 weaves and six types of yarns, which have been defined thanks to close collaboration of experts in computer graphics, art history and historical fabrics. Additionally, users can change the color of yarns and produce different 3D representations for a given fabric, which are interactive in real time. In this paper, we bring the details of the design and implementation of this tool, focusing on the input data, the strategy to process images, the 3D modelling of yarns, the definition of weaves and weaving techniques and the graphical user interface. In the results section, we show some examples of image analysis in order to subtract the design of historical fabrics, and then we provide 3D representations for all the considered weaving techniques, combining different types of yarns.

Continuous multi-body dynamic analysis of float-over deck installation with rapid load transfer technique in open waters

2021 ◽  
Vol 224 ◽  
pp. 108729
Author(s):  
Shujie Zhao ◽  
Xun Meng ◽  
Huajun Li ◽  
Dejiang Li ◽  
Qiang Fu
Keyword(s):  
Dynamic Analysis ◽  
Load Transfer ◽  
Multi Body ◽  
Body Dynamic

scholarly journals Research on Coupled Dynamic Model of Tracked Vehicles and Its Solving Method

2015 ◽  
Vol 2015 ◽  
pp. 1-10
Author(s):  
Yuliang Li ◽  
Chong Tang
Keyword(s):  
Dynamic Performance ◽  
Tractive Force ◽  
Actual Structure ◽  
Discrete Method ◽  
Tracked Vehicles ◽  
Coupled Equations ◽  
Calculation Results ◽  
Dynamic Software ◽  
Multi Body ◽  
Body Dynamic

In order to conveniently analyze the dynamic performance of tracked vehicles, mathematic models are established based on the actual structure of vehicles and terrain mechanics when they are moving on the soft random terrain. A discrete method is adopted to solve the coupled equations to calculate the acceleration of the vehicle’s mass center and tractive force of driving sprocket. Computation results output by the model presented in this paper are compared with results given by the model, which has the same parameters, built in the multi-body dynamic software. It shows that the steady state calculation results are basically consistent, while the model presented in this paper is more convenient to be used in the optimization of structure parameters of tracked vehicles.

Modelling of a Twin-Track Vehicle Model with Modular Wheel Suspensions

2012 ◽  
Vol 165 ◽  
pp. 214-218
Author(s):  
Michael Unterreiner ◽  
Dieter Schramm
Keyword(s):  
Mathematical Modelling ◽  
Jacobian Matrix ◽  
Vehicle Model ◽  
Different Types ◽  
Multi Body ◽  
Modelling Approach

A mathematical modelling approach of a multi-body wheel suspension is presented. The wheel suspension is modelled in a modular manner so that different types of vehicles can be simulated. The inter-changeability of the wheel suspensions is achieved by calculating the translational and rotational Jacobian matrix and its partial time derivatives for the wheel carrier and the wheel. The results of modelling the kinematics of a McPherson wheel suspension are shown.

Multi-body dynamic analysis of float-over installations

2012 ◽  
Vol 51 ◽  
pp. 1-15 ◽  
Author(s):  
L. Sun ◽  
R. Eatock Taylor ◽  
Y.S. Choo
Keyword(s):  
Dynamic Analysis ◽  
Multi Body ◽  
Body Dynamic

scholarly journals Multi Body Dynamic Equations of Belt Conveyor and the Reasonable Starting Mode

Symmetry ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1489
Author(s):  
Yongbo Guo ◽  
Fansheng Wang
Keyword(s):  
Finite Element ◽  
Recursive Formula ◽  
Conservative System ◽  
Conveyor Belt ◽  
Dynamic Equations ◽  
Lagrange’S Equation ◽  
Rigid Finite Element Method ◽  
Potential Capacity ◽  
Multi Body ◽  
Body Dynamic

Based on the rigid finite element method and multibody dynamics, a discrete model of a flexible conveyor belt considering the material viscoelasticity is established. RFE (rigid finite element) and SDE (spring damping element) are used to describe the rigidity and flexibility of a conveyor belt. The dynamic differential equations of the RFE are derived by using Lagrange’s equation of the second kind of the non-conservative system. The generalized elastic potential capacity and generalized dissipation force of the SDE are considered. The forward recursive formula is used to construct the conveyor belt model. The validity of dynamic equations of conveyor belt is verified by field test. The starting mode of the conveyor is simulated by the model.

scholarly journals Hydrodynamic Analysis of Self-Propulsion Performance of Wave-Driven Catamaran

2021 ◽  
Vol 9 (11) ◽  
pp. 1221
Author(s):  
Weixin Zhang ◽  
Ye Li ◽  
Yulei Liao ◽  
Qi Jia ◽  
Kaiwen Pan
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Dynamic Model ◽  
Dynamic Structure ◽  
Ocean Waves ◽  
Static State ◽  
Small Surface ◽  
Propulsion Performance ◽  
Multi Body ◽  
Body Dynamic

The wave-driven catamaran is a small surface vehicle driven by ocean waves. It consists of a hull and hydrofoils, and has a multi-body dynamic structure. The process of moving from static state to autonomous navigation driven by ocean waves is called “self-propulsion”, and reflects the ability of the wave-driven catamaran to absorb oceanic wave energy. Considering the importance of the design of the wave-driven catamaran, its self-propulsion performance should be comprehensively analysed. However, the wave-driven catamaran’s multi-body dynamic structure, unpredictable dynamic and kinematic responses driven by waves make it difficult to analyse its self-propulsion performance. In this paper, firstly, a multi-body dynamic model is established for wave-driven catamaran. Secondly, a two-phase numerical flow field containing water and air is established. Thirdly, a numerical simulation method for the self-propulsion process of the wave-driven catamaran is proposed by combining the multi-body dynamic model with a numerical flow field. Through numerical simulation, the hydrodynamic response, including the thrust of the hydrofoils, the resistance of the hull and the sailing velocity of the wave-driven catamaran are identified and comprehensively analysed. Lastly, the accuracy of the numerical simulation results is verified through a self-propulsion test in a towing tank. In contrast with previous research, this method combines multi-body dynamics with computational fluid dynamics (CFD) to avoid errors caused by artificially setting the motion mode of the catamaran, and calculates the real velocity of the catamaran.

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