Bar Linkage Research Articles

Development of Torque Sensor with High Sensitivity for Joint of Robot Manipulator Using 4-Bar Linkage Shape.

The torque sensor is used to measure the joint torque of a robot manipulator. Previous research showed that the sensitivity and the stiffness of torque sensors have trade-off characteristics. Stiffness has to be sacrificed to increase the sensitivity of the sensor. In this research, a new torque sensor with high sensitivity (TSHS) is proposed in order to resolve this problem. The key idea of the TSHS comes from its 4-bar linkage shape in which the angular displacement of a short link is larger than that of a long link. The sensitivity of the torque sensor with a 4-bar link shape is improved without decreasing stiffness. Optimization techniques are applied to maximize the sensitivity of the sensor. An actual TSHS is constructed to verify the validity of the proposed mechanism. Experimental results show that the sensitivity of TSHS can be increased 3.5 times without sacrificing stiffness.

4절링크를 기반으로 하는 신개념 ATC 메커니즘의 동역학 해석

4절링크를 기반으로 하는 신개념 ATC 메커니즘의 동역학 해석

健常者の歩行分析に基づく大腿義足用膝継手の回転中心位置の設計

In recent years, many type of trans-femoral prosthesis which has functions that support walking has been developed. Most commercially available prosthetic knee joint components for trans-femoral prosthesis users utilize four- bar linkages. Although stability of a four-bar linkage trans-femoral prosthesis has been established in level walking. However that walking pattern was unnaturalness compared with healthy subject. The purpose of this study was to design Instant center of rotation that achieves natural knee flexion by switching from knee extension moment to knee flexion moment at late stance phase. Therefore, we designed Instant center of rotation based on healthy subject gait analysis using the inverse dynamic procedure.

Система классификации плоских шарнирных четырёхзвенных механизмов

Система классификации плоских шарнирных четырёхзвенных механизмов

Complex shoulder girdle injuries following mountain bike accidents and a review of the literature

BackgroundMountain and road bike accidents are particularly common with the increased popularity of the sport. We reviewed the attendances in our emergency department over a 4-year period looking at cycling...

Self-repairing design process applied to a 4-bar linkage mechanism

Despite significant advances in modelling and design, mechanical systems almost inevitably fail at some point during their operative life. This can be due to a pre-existing design flaw, which is usually overcome in a revision, or more commonly due to some unexpected damage during operation. To overcome a failure during operation, a new method in designing machines or systems is proposed that creates a result, that is, resilient to both expected and unexpected failure. By shifting the focus from a detailed assessment of the underlying cause of failure to how that failure will manifest, a system becomes inherently resilient against a wide range of failure modes. The proposed process involves five steps: cause, detection, diagnosis, confirmation and correction. This is demonstrated with an application to a generic 4 bar linkage mechanism. Through this process, the system is able to return to a near perfect state even after a permanent deformation occurs in the mechanism. These results show the potential that this self-repairing design process has applications including robotics, manufacturing and other systems.

Optimal design of fractional-order PID controller for five bar linkage robot using a new particle swarm optimization algorithm

This paper introduces a new version of the particle swarm optimization (PSO) method. Two basic modifications for the conventional PSO algorithm are proposed to improve the performance of the algorithm. The first modification inserts adaptive accelerator parameters into the original velocity update formula of the PSO which speeds up the convergence rate of the algorithm. The ability of the algorithm in escaping from local optima is improved using the second modification. In this case, some particles of the swarm, which are named the superseding particles, are selected to be mutated with some probability. The proposed modified PSO (MPSO) is simple to be implemented, fast and reliable. To validate the efficiency and applicability of the MPSO, it is applied for designing optimal fractional-order PID (FOPID) controllers for some benchmark transfer functions. Then, the introduced MPSO is applied for tuning the parameters of FOPID controllers for a five bar linkage robot. Sensitivity analysis over the fractional order of the PID controller is also provided. Numerical simulations reveal that the MPSO can optimally tune the parameters of FOPID controllers.

Design of a statically balanced fully compliant grasper

Monolithic and thus fully compliant surgical graspers are promising when they provide equal or better force feedback than conventional graspers. In this work for the first time a fully compliant grasper is designed to exhibit zero stiffness and zero operation force. The design problem is addressed by taking a building block approach, in which a pre-existing positive stiffness compliant grasper is compensated by a negative stiffness balancer. The design of the balancer is conceived from a 4-bar linkage and explores the rigid-body-replacement method as a design approach towards static balancing. Design variables and sensitivities are determined through the use of a pseudo-rigid-body model. Final dimensions are obtained using rough hand calculations. Justification of the pseudo rigid body model as well as the set of final dimensions is done by non-linear finite element analysis. Experimental validation is done through a titanium prototype of 40mm size having an unbalanced positive stiffness of 61.2N/mm showing that a force reduction of 91.75% is achievable over a range of 0.6mm, with an approximate hysteresis of 1.32%. The behavior can be tuned from monostable to bistable. The rigid-body-replacement method proved successful in the design of a statically balanced fully compliant mechanism, thus, widening the design possibilities for this kind of mechanism.

The Design of Lift Mechanism the Tailgate for Pick-up Truck using the 4 bar Linkage

The Design of Lift Mechanism the Tailgate for Pick-up Truck using the 4 bar Linkage

Development of Exoskeleton 4-Bar Linkage Gripper for Front End Module (FEM) Assembly Process

In this paper, development of exoskeleton gripper targeted for FEM assembly process is described. This exoskeleton system is currently being under study for industry field application. The proposed gripper system is capable of robustly connecting bulky heavy-weighted FEM to exoskeleton robot system. In order to reduce the load on the exoskeleton, lightening method based on H-beam structure is used alongside with the usage of small actuators which was possible due to 4-bar linkage. Finally, performance of the developed gripper was validated through experiments.

Autonomous Chess Playing Robot

Autonomous Chess Playing Robot is a robot that can challenge a human's chess playing ability in a tangible environment with its varying difficulty level. As any other autonomous robot, ACPR is based upon three pillars, viz. electronics, programming, and mechanical design. The robot consists of a customized chess board below which LDR sensors have been fabricated on a PCB (Printed Circuit Board). Multiplexers also being laid on PCB provide a way for one-way serial communication between sensors and microcontroller. Linear sliders facilitate horizontal and vertical movement of the gripper to move a piece from one position to other. The linear sliders use rack and pinion mechanism while the gripper uses the concept of four bar linkage mechanism. The crucial element of the robot i.e. the intelligence has been incorporated with the help of MinMax algorithm supported by alpha-beta pruning. The microcontroller is connected to a computer terminal by a USB and the chess engine code runs on the computer terminal itself.

On the Synthesis of a Five Bar Linkage for Linear Trajectory Using a CAD Analysis

This paper demonstrates how to use CAD Software (Pro/ENGINEER in our case) to generate a cam profile. This cam will be used in a five bar linkage for which the input elements are synchronized through a cam-follower mechanism. The cam profile is generated so that the five bar mechanism produces a certain curve. The paper presents the synthesis method after which a simulation is executed to verify the results.

NX-Based Parametric Design of Precision Molding Machine

In this paper, NX-based parametric design of precision die-cutting machine was introduced according to enterprises' rapid design requirements. On the basis of the analysis of the classification and development trend of die cutting machine, the transmission system and stepper motors was studied, the four bar linkage mechanism was designed, and the design scheme was determined. Finally, UG/NX movement simulation was employed to show the working situation of the various mechanisms in the system, and parametric design of the whole mechanisms was realized.

Analysis Design and Roof Motion Track Simulation for Gob-Side Entry Retaining Hydraulic Support

The reliability of formwork support is directly related to gob-side entry retaining success. In this paper a dual function of supporting and filling formwork support is designed. Use SolidWorks software build 3D modeling and virtual assembly, The establishment of a movement model of the anti-four-bar linkage formwork template using numerical methods and get the motion trajectory of the roof. It has been verify that the anti-four bar linkage design of the hydraulic support is feasible.

Kinematic Analysis of Rectangular Path Generating Adjustable Four-Bar Linkage

This paper focuses on the kinematic analysis of rectangular path generating adjustable four-bar crank rocker linkage. One of the ground pivots of rocker side of the adjustable mechanism is subjected to continuous adjustment while the crank arm is given uniform angular velocity. Variations of coupler and rocker position, velocity and acceleration are computed for continuously changing phases of the adjustable four bar linkage. These kinematic parameters are compared with non-adjustable four-bar mechanism. Effect of the continuous adjustment on transmission angle and torque ratio are presented. The above procedures are implemented successfully in MATLAB environment and graphical results are presented.

Synthesis of Four Bar Slider Mechanism for Finitely Three Separated Positions

Movement of the heliostat tracking sun is able to achieve through simple four bar mechanism. Design methods for four bar linkage encompass a mathematical approach, trial and error method, function generation, motion synthesis and path synthesis. The paper presents a study of motion synthesis of four bar slider mechanism applies to heliostat movement. Mathematical equations used for the synthesis are presented and the results are compared with the graphical method. Procedure of various methods to determine the length and position of the links in case of desired positions of the coupler are presented. As a conclusion, both methods are able to achieve wanted results with an acceptable degree of accuracy. However, the graphical method is helpful to provide better insight of the system during designing the solution compared to the mathematical method.

Influence of joint clearance on kinematic and dynamic parameters of mechanism

Kinematic joints for dynamic analysis of multi-body mechanical systems assumed ideal or perfect. However, in a real mechanical kinematical joint clearance is always present. Such clearance is necessary for the component assemblage and to allow the relative motion between the connected bodies. This clearance is inevitable due to the manufacturing tolerances, material deformations, wear, and imperfections. The presence of such joint clearance degrades the performance of mechanical systems in virtue of the contact and impact forces that take place at the joint. Contact analysis is a computational bottleneck in mechanical design where the contact changes. Manual analysis is time-consuming and prone to error. To address these problems, a geometrical contact analysis method based on kinematic simulation, using CAD software is developed. An equivalent kinematic linkage mechanism is constructed according to contact position of pin and hole assembly. Results of kinematic and dynamic analysis of a four bar linkage with joint clearance shows that the contribution of joint forces at slower input speed also degrades the performance of mechanism.

Design and experimentation on passive vibration isolation systems using PZT- PDMS composite and a shape memory alloy wire integrated mechanism

Abstract Passive use of smart materials for vibration isolation of dynamic systems is drawing wide attention due to its flexibility, vast applicability and effectiveness in aerospace and automobile applications. In the present work, we design and investigate experimentally, the application of two vibration isolation systems based on such passive smart materials. First, a smart composite based on Lead Zirconate-Titanate (PZT) and Poly-dimethylsiloxane (PDMS) is considered as a conventional system. Further, a Shape Memory Alloy (SMA) wire integrated four bar linkage mechanism is chosen as a novel system for this study. In the first phase, vibration response of a single stage isolation system is obtained for a low frequency range from 10-70 Hz. The vibration isolation system comprises of neoprene rubber tubes as a spring element. Experiments are carried out with neoprene rubber blocks and piezoelectric (PZT)-PDMS composite. Finally, the piezoelectric damper is replaced by a new four bar linkage incorporating pre-stressed SMA wire in order to determine its efficiency of vibration isolation. The SMA wire undergoes pseudoelastic transformation at a temperature higher than austenite finish temperature due to loading and unloading upon induction of transverse vibrations from electro-dynamic shaker. Frequency responses and transmissibility of the proposed device are also analyzed. The experimental results project that SMA wire based passive damping system could be a very effective solution for vibration isolation. Future work will investigate the improvement of the design of SMA wire based vibration isolation system.

Design and Implementation of a 4-Bar linkage Gripper

Design of the end-effector of a robot is of high importance. This is the part of a robot that actually interacts with the object and does grip it. Without a suitable end-effector, a robot cannot function properly. Poorly designed gripper may result in slip of a component from the jaws of a gripper and even damage parts sometimes. A component may be hold with instability, and this can decrease system reliability. In this paper, discussion is made on design considerations that one needs to take into account while designing the 4-bar linkage gripper. The control system applied for it is also briefed.

Kinematic Analysis of a Spatial 6-Bar Linkage Mechanism

The door operator in metallurgical equipment is a spatial 6-bar linkage mechanism. The numerical model of motion and force of the mechanism was developed and the numerical solution was applied. A computer simulation was implemented. There is a high level of consistency between the solution and simulation. The torques required on driving crank have been studied. The influences of the self-lock conditions on the crank length and con-rod length have been explored. The effects of the length of crank and con-rode on the needed maximal torques of the crank have been studied, too. And the kinematics analysis attributes the lightening design of the slider structure on the basis of considering the sliders rigidness and intensity.