A Geometric Approach for Error Space Estimation of Planar Linkage

2021 ◽  
Author(s):  
Jianzhong Ding ◽  
Chunjie Wang
Keyword(s):  
Closed Form ◽  
Error Propagation ◽  
Evaluation Method ◽  
Geometric Approach ◽  
Simple Expression ◽  
Propagation Path ◽  
End Effector ◽  
3 Dimensional ◽  
Error Space ◽  
Four Bar Linkage

Abstract This article develops a geometric method to estimate the clearances-induced error space of any planar linkage. The error space discussed here represents the unconstrained mobility of the end-effector when actuators of the mechanism are locked, and is expressed by a connected geometry in 3-dimensional Euclidean frame {x, y, θ}. First, error space of the planar mechanism is modeled and closed-form expressions are derived. Then, levels of joints in error propagation analysis are defined and illustrated with an example of a eight-bar linkage, following which error propagation path among closed-loop structures is given. The modeling of error propagation and accumulation is introduced in detail. Moreover, a simplification technique is discussed for simple expression of the error space propagated from previous joints. This study provides a way to have a deep insight into the accuracy performance of any planar linkage and the proposed error space evaluation method is validated by case study of error space estimation of a four-bar linkage and a six-bar linkage. For the four-bar linkage, the structure with optimal accuracy is obtained. And for the six-bar linkage, the error space of the end-effector is expressed in closed form and visualized in the 3-dimensional frame. Finally, this work is concluded and advances of the proposed method are emphasized.

Studies on Isotropy of Planar 5-Bar Linkages

2004 ◽  
Author(s):  
C. Amarnath ◽  
K. N. Umesh
Keyword(s):  
Geometric Approach ◽  
Geometrical Approach ◽  
End Effector ◽  
Isotropic Point ◽  
Important Requirement ◽  
Point To Point

The ability to move at reasonable ease in all directions is an important requirement in the design of manipulators. The degree of ease of mobility varies from point to point in the workspace of the manipulator’s end effector. Maximum ease of mobility is obtained at an isotropic point, and the minimum occurs at singularities. An attempt has been made here to use a geometric approach for determining the isotropic points in the workspace of planar 5-bar linkages. The geometrical approach leads to interesting observations on the location of isotropic points in the workspace. The procedure also yields a technique for the synthesis of 5-bar linkages and associated coupler points exhibiting isotropic behaviour. Additionally it has been shown that coupler points exhibiting isotropic mobility occur in pairs.

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.

scholarly journals Controlling of a ROS-based robotic system in accordance to the assist-as-needed principle in end-effector based rehabilitation systems

2018 ◽  
Vol 4 (1) ◽  
pp. 199-202
Author(s):  
Sebastian Becker ◽  
Wiebke Hinterlang ◽  
Tim Eschert ◽  
Catherine Disselhorst-Klug
Keyword(s):  
Impedance Control ◽  
Proximal Part ◽  
The Elderly ◽  
Subjective Assessment ◽  
Robot Kinematics ◽  
Robotic Rehabilitation ◽  
End Effector ◽  
3 Dimensional ◽  
The Central Nervous System ◽  
Robotic Devices

AbstractStroke is one of the most frequent diseases among the elderly and often leads to an ongoing failure of functions in the central nervous system. Due to the plasticity of the brain affected may regain lost motor function by repetitive training. Robotic devices can be an approach to accelerate the rehabilitation process by maximizing patients’ training intensity. End-effector based robotic systems are particularly suitable for this purpose and often an advantage over exoskeletons since the proximal part of the upper limb remains under the control of the patient. Furthermore, the integration of the assistas- needed principle (AAN) into these devices enables individualized, adaptable robotic support to patients during therapy. In this study an end-effector based robotic rehabilitation device based on the Robot Operating System (ROS) framework is introduced. The system allows patients to perform 3- dimensional movements without a therapist’s assistance. With regard to the AAN, focus was based on impedance control and an additional real-time adaption of the impedance control parameters by using a feedback loop. 10 healthy subjects took part in this study to evaluate the overall concept with regard to usability and quality of the supported movement. Hence, the three most promising adaption models of AAN (without adaption, adaption according to position and time, adaption according to velocity) under three different levels of movement support (0%, 50%, 100%) were investigated by administering a self-designed questionnaire and the robot kinematics. The results showed no significant differences between the three different adaption models of AAN. However, the subjective assessment of the movements was in keeping with robot kinematics and the control approaches as well as the overall system have experienced remarkable support.

Understanding the Aortic Root Using Computed Tomographic Assessment: A Potential Pathway to Improved Customized Surgical Repair

2021 ◽  
Author(s):  
Justin T. Tretter ◽  
Yu Izawa ◽  
Diane E. Spicer ◽  
Kenji Okada ◽  
Robert H. Anderson ◽  
...  
Keyword(s):  
Aortic Root ◽  
Surgical Repair ◽  
Geometric Approach ◽  
3 Dimensional ◽  
Computed Tomographic ◽  
Contrast Enhanced ◽  
Surgical Evaluation ◽  
Multiplanar Reformatting ◽  
Selection Of Patients ◽  
Selection Of

There is continued interest in surgical repair of both the congenitally malformed aortic valve, and the valve with acquired dysfunction. Aortic valvar repair based on a geometric approach has demonstrated improved durability and outcomes. Such an approach requires a thorough comprehension of the complex 3-dimensional anatomy of both the normal and congenitally malformed aortic root. In this review, we provide an understanding of this anatomy based on the features that can accurately be revealed by contrast-enhanced computed tomographic imaging. We highlight the complimentary role that such imaging, with multiplanar reformatting and 3-dimensional reconstructions, can play in selection of patients, and subsequent presurgical planning for valvar repair. The technique compliments other established techniques for perioperative imaging, with echocardiography maintaining its central role in assessment, and enhances direct surgical evaluation. This additive morphological and functional information holds the potential for improving selection of patients, surgical planning, subsequent surgical repair, and hopefully the subsequent outcomes.

scholarly journals Analytical Calculation for Capacitances of Electrode Patterns in Touch Panels

2017 ◽  
Vol 3 (1) ◽  
Author(s):  
Bau-Jy Liang ◽  
Don-Gey Liu ◽  
Chia-Hung Yeh ◽  
Hsiao-Chun Chen ◽  
Yu-Chen Fang ◽  
...  
Keyword(s):  
Analytical Solution ◽  
Closed Form ◽  
Analytical Method ◽  
Analytical Calculation ◽  
3 Dimensional ◽  
Simulation Results ◽  
Complex Patterns ◽  
Touch Panels

AbstractIn this paper, an accurate 3-dimensional (3-D) analytical solution is proposed to calculate the projective capacitances of touch panels. In this study, both simple and complex patterns were investigated for the calculation. We propose a partition strategy to divide a pattern into many rectangular or triangular sub-patterns. Each sub-pattern can be further cut into 2-D slices. The capacitance of a 2-D slice was then solved by our closed-form formulae. The total capacitance of a pattern was obtained by integrating up all the partial capacitances of the slices. In this study, the precision of our analytical method was examined by comparing the simulation results obtained from Q3D

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.

A Three-Gear Linkage for Generating Dwell Motions

2000 ◽  
Vol 123 (4) ◽  
pp. 637-640 ◽  
Author(s):  
L. Beiner
Keyword(s):  
Closed Form ◽  
Textile Printing ◽  
Four Bar Linkage

This study deals with a three-gear four-bar linkage that transforms a uniform input crank rotation into a forward-dwell motion of the output gear. Closed-form relations allowing to synthesize a geared linkage generating an approximate dwell of specified tolerance are derived. Such intermittent motions are useful in various transport and indexing devices found in textile, printing and packaging machines.

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.

Sign in / Sign up

Export Citation Format

Share Document