On the Solution of Region-Based Planar Six-Bar Motion Generation for Four Finitely Separated Position

2012 ◽  
Author(s):  
Jianyou Han ◽  
Tong Yang
Keyword(s):  
Local Solution ◽  
Synthesis Problem ◽  
Motion Generation ◽  
End Effector ◽  
Numerical Example ◽  
Region Method ◽  
Solution Region ◽  
End Effectors ◽  
Four Bar Linkage ◽  
The Way

This paper addresses the synthesis problem of Watt-I and Stephenson-IIIa six-bar linkages motion generation for four specified task positions. Both of them have one thing in common — theirs floating links which used as end-effectors are connected to a coupler plane of a four-bar linkage. Once the task positions of end-effector are given, we can calculate the corresponding positions of the coupler plane. Then our focus is on the synthesis of a four bar-linkage and the way that a RR chain can be attached to constrain the links of this four-bar linkage. This synthesis problem of four-bar linkage motion generation can be settled by a solution region method. And then we can present an equation of pivot curve that each point on this curve can generate a satisfactory RR chain. A new local solution region that is more practicable is presented by the last numerical example.

Design of an Underactuated Robotic End-Effector With a Focus on Power Tool Manipulation

2014 ◽  
Author(s):  
Michael Rouleau ◽  
Dennis Hong
Keyword(s):  
Disaster Response ◽  
Degrees Of Freedom ◽  
Humanoid Robot ◽  
Servo Motor ◽  
End Effector ◽  
Design Considerations ◽  
Wide Range ◽  
End Effectors ◽  
Four Bar Linkage ◽  
Careful Design

End-effectors require careful design considerations to be able to successfully hold and use power tools while maintaining the ability to also grasp a wide range of other objects. This paper describes the design of an end effector for a humanoid robot built for disaster response scenarios. The end effector is comprised of two independently actuated fingers with two opposing stationary rigid hollow pylons built to allow the pinching of objects and to provide protection for the opposing fingers when retracted and not in use. Each finger has two degrees of freedom (DOF) and is actuated with one servo motor through the use of an underactuated four bar linkage. Using only two fingers and two actuators the end-effector has the ability to hold a power tool while also being able to simultaneously actuate the trigger of the tool independently. The combination of compliant fingers and rigid pylons along with the careful design of the palm structure creates a strong robust dexterous end-effort that is simple to control.

Solution Region Synthesis Method for Six Positions Synthesis of 5-SS Spatial Linkage

2016 ◽  
Author(s):  
Jianyou Han ◽  
Guangzhen Cui ◽  
Junjie Hu
Keyword(s):  
Systematic Approach ◽  
Synthesis Method ◽  
Degree Of Freedom ◽  
Dimensional Synthesis ◽  
End Effector ◽  
Region Method ◽  
Solution Region ◽  
The One

This paper presents a systematic approach to perform the dimensional synthesis of spatial 5-SS (spherical-spherical) link-ages for six specified positions of the end-effector. The dimensional synthesis equations for a SS link are formulated and solved. We synthesize five SS links to connect the base and end-effector, and then obtain the one-degree-of-freedom spatial 5-SS linkage, which can move through six specified positions. We use the solution region method to build the planar solution region expressing the linkages, due to there are infinite linkages for six positions synthesis. It is convenient to select the linkages from the solution region for designers. The applicability of the proposed approach is illustrated by the example.

scholarly journals Force-Free Control for Direct Teaching of a Surgical Assistant Robot End Effector with Wire-Driven Bidirectional Telescopic Mechanism

Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3498
Author(s):  
Youqiang Zhang ◽  
Cheol-Su Jeong ◽  
Minhyo Kim ◽  
Sangrok Jin
Keyword(s):  
Control Algorithm ◽  
Position Control ◽  
Friction Model ◽  
Surgical Instruments ◽  
Control Input ◽  
End Effector ◽  
Motor Current ◽  
Direct Teaching ◽  
End Effectors ◽  
Teaching Operation

This paper shows the design and modeling of an end effector with a bidirectional telescopic mechanism to allow a surgical assistant robot to hold and handle surgical instruments. It also presents a force-free control algorithm for the direct teaching of end effectors. The bidirectional telescopic mechanism can actively transmit force both upwards and downwards by staggering the wires on both sides. In order to estimate and control torque via motor current without a force/torque sensor, the gravity model and friction model of the device are derived through repeated experiments. The LuGre model is applied to the friction model, and the static and dynamic parameters are obtained using a curve fitting function and a genetic algorithm. Direct teaching control is designed using a force-free control algorithm that compensates for the estimated torque from the motor current for gravity and friction, and then converts it into a position control input. Direct teaching operation sensitivity is verified through hand-guiding experiments.

scholarly journals Magnetic Driven Two-Finger Micro-Hand with Soft Magnetic End-Effector for Force-Controlled Stable Manipulation in Microscale

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 410
Author(s):  
Dan Liu ◽  
Xiaoming Liu ◽  
Pengyun Li ◽  
Xiaoqing Tang ◽  
Masaru Kojima ◽  
...  
Keyword(s):  
Magnetic Force ◽  
Force Feedback ◽  
Soft Magnetic ◽  
End Effector ◽  
Force Microscopy ◽  
System A ◽  
Atomic Force ◽  
Afm Probe ◽  
End Effectors ◽  
Fixed End

In recent years, micromanipulators have provided the ability to interact with micro-objects in industrial and biomedical fields. However, traditional manipulators still encounter challenges in gaining the force feedback at the micro-scale. In this paper, we present a micronewton force-controlled two-finger microhand with a soft magnetic end-effector for stable grasping. In this system, a homemade electromagnet was used as the driving device to execute micro-objects manipulation. There were two soft end-effectors with diameters of 300 μm. One was a fixed end-effector that was only made of hydrogel, and the other one was a magnetic end-effector that contained a uniform mixture of polydimethylsiloxane (PDMS) and paramagnetic particles. The magnetic force on the soft magnetic end-effector was calibrated using an atomic force microscopy (AFM) probe. The performance tests demonstrated that the magnetically driven soft microhand had a grasping range of 0–260 μm, which allowed a clamping force with a resolution of 0.48 μN. The stable grasping capability of the magnetically driven soft microhand was validated by grasping different sized microbeads, transport under different velocities, and assembly of microbeads. The proposed system enables force-controlled manipulation, and we believe it has great potential in biological and industrial micromanipulation.

scholarly journals Deviation Tolerance Performance Evaluation and Experiment of Picking End Effector for Famous Tea

Agriculture ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 128
Author(s):  
Yingpeng Zhu ◽  
Chuanyu Wu ◽  
Junhua Tong ◽  
Jianneng Chen ◽  
Leiying He ◽  
...  
Keyword(s):  
Success Rate ◽  
Negative Pressure ◽  
Evaluation Method ◽  
Orthogonal Experiment ◽  
Spatial Position ◽  
End Effector ◽  
Significance Level ◽  
Growth Environment ◽  
End Effectors ◽  
Average Success Rate

Accurately obtaining the posture and spatial position of tea buds through machine vision and other technologies is difficult due to the small size, different shapes, and complex growth environment of tea buds. Therefore, end effectors are prone to problems, such as picking omission and picking error. This study designs a picking end effector based on negative pressure guidance for famous tea. This end effector uses negative pressure to guide tea buds in a top-down manner, thereby correcting their posture and spatial position. Therefore, the designed end effector has deviation tolerance performance that can improve the picking success rate. The pre-experiment is designed, the tip of apical bud is referred to as the descent position, and the negative pressure range is determined to be 0.6 to 0.9 kPa. A deviation tolerance orthogonal experiment is designed. Experimental results show that various experimental factors are ranked in terms of the significance level of the effect on the average success rate, and the significance ranking is as follows: negative pressure (P) > pipe diameter (D) > descent speed (V). An evaluation method of deviation tolerance performance is presented, and the optimal experiment factor-level combination is determined as: P = 0.9 kPa, D = 34 mm, V = 20 mm/s. Within the deviation range of a 10 mm radius, the average success rate of the negative pressure guidance of the end effector is 97.36%. The designed end effector can be applied to the intelligent picking of famous tea. This study can provide a reference for the design of similar picking end effectors for famous tea.

Parameterization of Three-Dimensional Rigid Body Guidance Incorporating Planar Gear Connections in a Spatial Closed-Loop Mechanism With Parallel Consecutive Axes

2008 ◽  
Author(s):  
Javier Rolda´n Mckinley ◽  
Carl Crane ◽  
David B. Dooner
Keyword(s):  
Computer Animation ◽  
Closed Loop ◽  
Three Dimensional ◽  
Motion Generation ◽  
Repetitive Motion ◽  
End Effector ◽  
Spatial Mechanism ◽  
Joint Axis ◽  
Position And Orientation ◽  
Six Degree Of Freedom

This paper introduces a reconfigurable closed-loop spatial mechanism that can be applied to repetitive motion tasks. The concept is to incorporate five pairs of non-circular gears into a six degree-of–freedom closed-loop spatial chain. The gear pairs are designed based on given mechanism parameters and a user defined motion specification of a coupler link of the mechanism. It is shown in the paper that planar gear pairs can be used if the spatial closed-loop chain is comprised of six pairs of parallel joint axes, i.e. the first joint axis is parallel to the second, the third is parallel to the fourth, ..., and the eleventh is parallel to the twelfth. This paper presents the synthesis of the gear pairs that satisfy a specified three-dimensional position and orientation need. Numerical approximations were used in the synthesis the non-circular gear pairs by introducing an auxiliary monotonic parameter associated to each end-effector position to parameterize the motion needs. The findings are supported by a computer animation. No previous known literature incorporates planar non-circular gears to fulfill spatial motion generation needs.

scholarly journals Synthesis of Spatial RPRP Closed Linkages for a Given Screw System

2011 ◽  
Vol 3 (2) ◽  
Author(s):  
Alba Perez-Gracia
Keyword(s):  
Design Method ◽  
Parallel Robots ◽  
Synthesis Problem ◽  
Dimensional Synthesis ◽  
End Effector ◽  
Serial Chain

The dimensional synthesis of spatial chains for a prescribed set of positions can be applied to the design of parallel robots by joining the solutions of each serial chain at the end-effector. This design method does not provide with the knowledge about the trajectory between task positions and, in some cases, may yield a system with negative mobility. These problems can be avoided for some overconstrained but movable linkages if the finite-screw system associated with the motion of the linkage is known. The finite-screw system defining the motion of the robot is generated by a set of screws, which can be related to the set of finite task positions traditionally used in the synthesis theory. The interest of this paper lies in presenting a method to define the whole workspace of the linkage as the input task for the exact dimensional synthesis problem. This method is applied to the spatial RPRP closed linkage, for which one solution exists.

Kinematic Analyses of 5-DOF 3-RCRR Parallel Mechanism

2005 ◽  
Author(s):  
Zhen Huang ◽  
Si J. Zhu
Keyword(s):  
Reference Point ◽  
Parallel Mechanism ◽  
Screw Theory ◽  
Mobility Analysis ◽  
End Effector ◽  
Numerical Example ◽  
Rotation Center ◽  
Kinematic Analyses ◽  
Base Platform ◽  
Virtual Pairs

This paper presents the kinematic analyses of a 5-DOF 3-RCRR parallel mechanism. The end-effector of this mechanism can rotate round rotation center and one reference point on it can translate in a plane parallels to the base platform. Since the traditional Kutzbach-Gru¨bler formula is not valid for this mechanism, the modified Kutzbach-Gru¨bler formula and screw theory are used in the mobility analysis. The Duffy’s spherical analytic theory is used in forward/reverse position analyses. In forward/reverse velocity/acceleration analyses, virtual mechanism principle is used to build a virtual parallel mechanism (3-PvRCRR), which is equivalent to the initial mechanism (3-RCRR) on kinematics if all rates of virtual pairs (Pv) are set to be zero. At the end, some kinematics curves are presented with a numerical example.

A Gripper for Handling Large Leather Plies Stacked on Beams

2015 ◽  
Author(s):  
David Corinaldi ◽  
Massimo Callegari ◽  
Matteo-Claudio Palpacelli ◽  
Giacomo Palmieri
Keyword(s):  
Statistical Analysis ◽  
Confidence Interval ◽  
Irregular Shape ◽  
Production Costs ◽  
Preliminary Design ◽  
Leather Industry ◽  
End Effector ◽  
Great Confidence ◽  
Four Bar Linkage

The paper presents the preliminary design of a novel gripper able to grasp large non-rigid materials that has been conceived to face the challenge of automatic handling tasks in the leather industry. The design has been driven by the requirements to limit production costs and the complexity of the grasping device. A statistical analysis of the different templates sizes has allowed to identify a fixed configuration of the gripping points able to properly pick all the sheets within a great confidence interval. According to the varying shape of the leather templates themselves, that is due to their stacking in plies on the beam, the trajectory of the gripping points has been studied and arranged. Due to the irregular shape of the large sheets that are handled, the edges of the non-rigid materials out of the gripping area might flutter during the transferring phase: a four-bar linkage has been specifically designed, so that the motion of its end-effector prevents unwanted leather creases.

scholarly journals An investigation of various actuation mechanisms in robot arm

2019 ◽  
Vol 52 (9-10) ◽  
pp. 1299-1307 ◽  
Author(s):  
J Prakash ◽  
M Ilangkumaran
Keyword(s):  
Analytical Approach ◽  
Robot Arm ◽  
Force Analysis ◽  
Linkage Mechanism ◽  
Actuation Mechanism ◽  
Research Activities ◽  
Grasping Force ◽  
Object Shapes ◽  
End Effectors ◽  
Four Bar Linkage

Many research activities have been carried out to develop a simple mechanism for grasping irregular object shapes using two- or three-fingered robot end effectors. The idea behind this work is to develop three-fingered intelligent grippers that are capable of sensing different factors like weight, effort required, compactness, robustness, and stability of the object held during the manipulations. In this paper, five different actuation mechanisms, namely, edge-cam-operated actuation mechanism, toggle-linkage-based actuation mechanism, wedge-cam-operated gripper, sliding slotted pin–ball joint arrangement, and rack-and-pinion-operated four-bar linkage mechanism, are introduced. The actuation and grasping force of the gripper are to be determined using the analytical approach (static force analysis). Finally, the effective intelligent gripper mechanism is identified based on grasping force for grasping 1 kg weight of a prespecified object.

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