A family of novel compliant linear-motion mechanisms based on compliant rolling-contact element pivot

2021 ◽  
pp. 1-26
Author(s):  
Tonglong Huo ◽  
Jingjun Yu ◽  
Hongzhe Zhao ◽  
Xian Wei

Abstract Compliant linear-motion mechanisms are of great use in precision machines, due to their excellent performances such as infinite resolution and low cost. The accuracy of the mechanisms is an important consideration for mechanical design in applications, especially in the case of large working load. Considering that COmpliant Rolling-contact Element (CORE) pivot is characterized with high bearing capacity, the paper adopts it as a building block to design a family of compliant linear-motion mechanisms for applications of heavy load. These mechanisms are achieved by replacing four rigid pivots in a parallel four-bar mechanism with CORE pivots, and the motion accuracy is improved by means of contacting surfaces design of four CORE pivots. Firstly, structures of CORE pivot are introduced and five extended arrangements for bearing heavy load are presented. Meanwhile, motion for the CORE pivot is analyzed and preconditions for achieving a pure roll are discussed. Then, configuration of the compliant linear-motion mechanisms constructed by CORE pivots is obtained, and kinematics of the mechanisms is analyzed and parametric design condition for rectilinear motion is modeled. Based on the condition, detailed topological structures of the mechanisms are designed. Finally, motion simulations and experiment tests are implemented to verify accuracy of the proposed mechanisms. The results demonstrate that the mechanisms proposed in this paper are capable of offering a high-precision linear motion and providing a promising application prospect in precision machines.

2021 ◽  
Author(s):  
Tonglong Huo ◽  
Jingjun Yu ◽  
Hongzhe Zhao ◽  
Xian Wei

Abstract Compliant linear-motion mechanisms are of great use in precision machines, due to their excellent performances such as infinite resolution and low cost. The accuracy of the mechanisms is an important consideration for mechanical design in applications, especially in the case of large working load. Considering Compliant Rolling-contact Element (CORE) pivot is characterized with high bearing capacity, the paper adopts it as a building block to design a family of compliant linear-motion mechanisms for heavy load applications. These mechanisms are achieved by replacing four rigid pivots in parallel four-bar mechanism with CORE pivots, and the motion accuracy is improved by means of contacting surfaces design of four CORE pivots. Firstly, the CORE pivot is introduced and five extended arrangements for bearing heavy load are given. Meanwhile, configuration of the compliant linear-motion mechanisms constructed by CORE pivots is obtained. In addition, kinematics of the mechanisms is analyzed and parametric design condition for achieving rectilinear motion is modeled. Based on the condition, detailed topological structures of the mechanisms are designed. Finally, motion simulations are implemented to verify accuracy of the proposed mechanisms. The results demonstrate that the mechanisms proposed in this paper are capable of offering a high-precision linear motion and providing a promising application prospect in precision machines.


Author(s):  
Luis Arturo Gómez Malagón ◽  
João Luiz Vilar Dias
Keyword(s):  

Robotica ◽  
2010 ◽  
Vol 29 (5) ◽  
pp. 733-743 ◽  
Author(s):  
Conghui Liang ◽  
Hao Gu ◽  
Marco Ceccarelli ◽  
Giuseppe Carbone

SUMMARYA mechanical design and dynamics walking simulation of a novel tripod walking robot are presented in this paper. The tripod walking robot consists of three 1-degree-of-freedom (DOF) Chebyshev–Pantograph leg mechanisms with linkage architecture. A balancing mechanism is mounted on the body of the tripod walking robot to adjust its center of gravity (COG) during walking for balancing purpose. A statically stable tripod walking gait is performed by synchronizing the motions of the three leg mechanisms and the balancing mechanism. A three-dimensional model has been elaborated in SolidWorks® engineering software environment for a characterization of a feasible mechanical design. Dynamics simulation has been carried out in the MSC.ADAMS® environment with the aim to characterize and to evaluate the dynamic walking performances of the proposed design with low-cost easy-operation features. Simulation results show that the proposed tripod walking robot with proper input torques, gives limited reaction forces at the linkage joints, and a practical feasible walking ability on a flatten ground.


2020 ◽  
Vol 2 (2) ◽  
pp. 280-293
Author(s):  
Mathew G. Pelletier ◽  
Greg A. Holt ◽  
John D. Wanjura

The removal of plastic contamination in cotton lint is an issue of top priority to the U.S. cotton industry. One of the main sources of plastic contamination showing up in marketable cotton bales, at the U.S. Department of Agriculture’s classing office, is plastic from the module wrap used to wrap cotton modules produced by the new John Deere round module harvesters. Despite diligent efforts by cotton ginning personnel to remove all plastic encountered during unwrapping of the seed cotton modules, plastic still finds a way into the cotton gin’s processing system. To help mitigate plastic contamination at the gin; an inspection system was developed that utilized low-cost color cameras to see plastic on the module feeder’s dispersing cylinders, that are normally hidden from view by the incoming feed of cotton modules. This technical note presents the design of an automated intelligent machine-vision guided cotton module-feeder inspection system. The system includes a machine-learning program that automatically detects plastic contamination in order to alert the cotton gin personnel as to the presence of plastic contamination on the module feeder’s dispersing cylinders. The system was tested throughout the entire 2019 cotton ginning season at two commercial cotton gins and at one gin in the 2018 ginning season. This note describes the over-all system and mechanical design and provides an over-view and coverage of key relevant issues. Included as an attachment to this technical note are all the mechanical engineering design files as well as the bill-of-materials part source list. A discussion of the observational impact the system had on reduction of plastic contamination is also addressed.


2006 ◽  
Vol 1 (2) ◽  
pp. 105-112 ◽  
Author(s):  
Rahul D. Sathe ◽  
David N. Ku

Over 7 million Americans suffer from chronic venous insufficiency (CVI), a disease that affects the venous system of the lower extremities. Problems associated with CVI include ulcerations, bleeding, swelling, and varicose veins, as well as deep vein thrombosis and pulmonary embolism. The presence of CVI is the result of incompetent, or malfunctioning, one-way vein valves in leg veins. There are few effective clinical therapies for treating CVI and there are currently no prosthetic vein valves commercially available. The purpose of this study was to define clinically relevant design requirements, develop functional tests for assessing a prosthetic vein valve, and design and fabricate a functional prosthetic vein valve for eventual clinical use. Engineering design methods were used to develop the valve, building a product based on well-defined consumer needs and design specifications. Emphasis was placed on creating a valve with potential clinical functionality. This clinical functionality was distilled into three major design criteria: that the valve (1) withstand backpressure of 300mmHg with less than 1.0mL∕min of leakage; (2) open with distal pressure gradients less than 5mmHg; and (3) meet criteria 1 and 2 after 500,000cycles of opening and closing. Hydrostatic testing was conducted to measure the opening pressure and reflux leak rate of the valve. Cyclic life functionality was assessed using a cyclic flow loop simulating physiologic conditions of cyclic flow and pressure found in leg veins. The valve opened with a pressure of 2.6mmHg±0.7mmHg, which matches physiologic vein valve function. The valve also withstood 300mmHg of backpressure with less than 0.5mL∕min of leakage, and maintained this performance even after 508,000cycles of opening and closing in simulated physiologic conditions. The valve’s burst pressure was a minimum of 530mmHg±10mmHg, six times greater than physiologic pressure natural vein valves experience. The valve continued to function well in an environment of vein-like tube expansion. The newly designed bi-leaflet prosthetic valve is comprised of a flexible, biocompatible material. Bench test results have shown that the valve is hydrodynamically functional and meets the mechanical design criteria for backpressure competency and opening pressure after 500,000cycles. Finally, the valve can be manufactured easily with low cost.


Author(s):  
ELIEL EDUARDO MONTIJO-VALENZUELA ◽  
SAUL DANIEL DURAN-JIMENEZ ◽  
LUIS ALBERTO ALTAMIRANO-RÍOS ◽  
JOSÉ ISAEL PÉREZ-GÓMEZ ◽  
OSCAR SALMÓN-AROCHI

The objective of this research is to manufacture a prototype of a teaching die for the specialty of precision mechanical design in mechatronic engineering, in order to achieve the skills required in unit two, regarding dies. The methodology used consists of five stages: 1. Definition of the preliminary conditions. 2. Theoretical calculations for die design. 3. Design, modeling and assembly using computer-aided software (CAD) of the parts that make up the die. 4. Validation with simulation of finite element analysis (AEF). 5. Manufacture of parts and physical assembly of the die. A functional prototype was obtained with which the teacher and student can perform calculations, designs and CAD models, AEF analysis of the static and fatigue type, manufacture of rapid prototypes using 3D printing, the identification of the parts that make up a die and their functioning. The advantage of this prototype, compared to metal die-cutting machines, is its low cost of production and manufacturing, it does not require expensive and specialized machinery for manufacturing, specific designs can be made by the students and its subsequent manufacture within the laboratories of the Technological Institute of Hermosillo.


Author(s):  
Von-Wun Soo ◽  
Tse-Ching Wang

A framework IPD (Iterative Parametric Design) is proposed to assist the iterative parametric mechanical design process. To effectively find a set of satisfiable values for the design parameters the key is to find good heuristics to adjust or tune the parametric values resulting from previous design iterations. We propose that heuristics can come from two aspects by both qualitative and quantitative reasoning. Qualitative reasoning, based on confluences, provides global control over the feasible directions of variable adjustments, while quantitative reasoning, based on the dependency network and perturbation analysis, can be used to propose actual quantity of local variable adjustments. We used the design of a helical compression spring as an example to illustrate the performance of IPD system. We show that IPD can often find a solution faster than those without guidance of qualitative and quantitative reasoning.


Author(s):  
Kun Sun ◽  
Boi Faltings

Abstract Knowledge-based CAD systems limit designers’ creativity by constraining them to work with the prototypes provided by the systems’ knowledge bases. We investigate knowledge-based CAD systems capable of supporting creative designs in the example domain of elementary mechanisms. We present a technique based on qualitative explanations which allows a designer to extend the knowledge base by demonstrating a structure which implements a function in a creative way. Structure is defined as the geometry of the parts, and function using a general logical language based on qualitative physics. We argue that the technique can accommodate any creative design in the example domain, and we demonstrate the technique using an example of a creative design. The use of qualitative physics as a tool for extensible knowledge-based systems points out a new and promising application area for qualitative physics.


2021 ◽  
pp. 1-36
Author(s):  
Shubhdildeep S. Sohal ◽  
Bijo Sebastian ◽  
Pinhas Ben-Tzvi

Abstract This paper presents a self-reconfigurable modular robot with an integrated 2-DOF active docking mechanism. Active docking in modular robotic systems has received a lot of interest recently as it allows small versatile robotic systems to coalesce and achieve the structural benefits of large systems. This feature enables reconfigurable modular robotic systems to bridge the gap between small agile systems and larger robotic systems. The proposed self-reconfigurable mobile robot design exhibits dual mobility using a tracked drive mechanism for longitudinal locomotion and a wheeled drive mechanism for lateral locomotion. The 2-DOF docking interface allows for efficient docking while tolerating misalignments. To aid autonomous docking, visual marker-based tracking is used to detect and re-position the source robot relative to the target robot. The tracked features are then used in Image-Based Visual Servoing to bring the robots close enough for the docking procedure. The hybrid-tracking algorithm allows eliminating external pixelated noise in the image plane resulting in higher tracking accuracy along with faster frame update on a low-cost onboard computational device. This paper presents the overall mechanical design and the integration details of the modular robotic module with the docking mechanism. An overview of the autonomous tracking and docking algorithm is presented along-with a proof-of-concept real world demonstration of the autonomous docking and self-reconfigurability. Experimental results to validate the robustness of the proposed tracking method, as well as the reliability of the autonomous docking procedure, are also presented.


2013 ◽  
Vol 2013 (1) ◽  
pp. 000039-000044
Author(s):  
Gary Gu ◽  
Jon Chadwick ◽  
Daniel Jin

Applications of Wafer Level Packages (WLPs) have shown tremendous growth in the rapid developing smartphones and other portable electronic devices. The technology trends lead to smaller chip size, low cost, and more integrated functions, but also face higher reliability requirements due to the reduced number of solder bumps as well as smaller bump size and height. New assembly technologies such as flexible phone board and conformal coating also brought up new thermo-mechanical reliability challenges. Based on 3D finite element modeling, the current studies focus on solder joint reliability of WLPs and compared between flex based and traditional rigid based WLP assemblies. Conformal coated and underfilled WLPs as well as some bump parameters are also studied. The parametric studies were carried out in ANSYS and all models were created by using APDL (ANSYS Parametric Design Language) scripts. Each simulation starts from stress free status set at solder reflow temperature and were subjected to thermal cyclic load between −40 and +125°C with ramp and dwell time. Creep strain was considered for solder alloys and kinematic plastic hardening was considered for other elastic-plastic materials. The solder fatigue life is estimated by using modified Coffin-Manson equation and was compared with available thermal cycling test data. The results show that underfill is still the most effective option and conformal coating can play an important role if the right material is selected. Bump parameters such as height, which have certain effects on the solder reliability on WLP-on-Rigid, have limited impact on WLP-on-Flex assembly.


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