Synthesis method of new weakly-coupled 5-DOF compliant parallel mechanism

Yajie Zhou,Jing Sun,Fengkui Zhang,Shihua Li 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8

Compared with the strongly-coupled parallel mechanism, the weakly-coupled mechanism can realize two kinds of mutually independent motions. In this paper, a new method for type synthesis of weakly-coupled compliant parallel mechanisms is proposed. The synthesis conditions, that is, the synthesis conditions of the shared flexure hinges and synthesis condition of the weakly-coupled, are given. The synthesis process is formulated. From the perspective of mechanism innovation, a new synthesis idea of weakly-coupled CPMs is introduced. New weakly-coupled CPMs without intermediate platform are obtained by sharing the flexure hinges of two compliant parallel mechanisms. To obtain five degree of freedom (5-DOFs) weakly-coupled compliant parallel mechanisms, two kinds of sub-sets of compliant mechanism blocks, a two-rotation and one-translation compliant mechanism and a twotranslation compliant mechanism are proposed. With the proposed synthesis method, two blocks are indirectly connected by sharing flexure hinges to obtain an integral mechanism. Then, new 5-DOF weakly-coupled compliant parallel mechanisms are proposed by the synthesis conditions. Additionally, finite element simulation is carried out to verify the correctness of the proposed synthesis method. Thirteen new 5-DOF weakly-coupled compliant parallel mechansims have been synthesized, which enriches the compliant parallel mechanism configurations. And, they have simple structure, compact structure, ease of control and light weight. The synthesized 5-DOF weakly-coupled compliant parallel mechanisms have potential application to pointing, vibration isolation and mirror adjustment platform.

우수한 기구학 특성을 가지는 새로운 병렬형 구형 3자유도 메커니즘의 구현

이석희(S. H. Lee),김희국(W. K. Kim),오세민(S. M. Oh),이병주(B. J. Yi) 한국정밀공학회 2004 한국정밀공학회 학술발표대회 논문집 Vol.2004 No.10월

In our pervious paper, a new parallel-type spherical 3-degree-of-freedom mechanism consisting of a two-degree-of-freedom parallel module and a serial RRR subchain was proposed[1]. In this paper, its improved version is suggested and implemented. Differently from the previous 3-dof spherical mechanism, gear chains are incorporated into the current version of the mechanism to drive the distal revolute joint of the serial subchain from the base of the mechanism and in fact, the modification significantly improves kinematic characteristics of the mechanism within its workspace. Firstly, after a brief description on its structure, the closed-form solutions of both the forward and the reverse position analysis are derived. Secondly, the first-order kinematic model of the mechanism for the inputs which are assumed to be located at the base is derived. Thirdly, through the simulations of the kinematic analysis via. kinematic isotropic index, it is confirmed that the mechanism has much more improved isotropic properties throughout the workspace of the mechanism than the previous mechanism in [1]. Lastly, the proposed mechanism is implemented to verify the results from this analysis.

Type synthesis of the fully-decoupled two-rotational and one-translational parallel mechanism

Yanbin Zhang,Xuemin Wei,Shuang Zhang,Zhenzhen Chang,Yaoguang Li 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.12

Type synthesis of parallel mechanism is regarded as the theoretical basis and source for the original innovation design of mechanical devices and robots. A new method for type synthesis of the fully-decoupled two-rotational and one-translational (2R1T) parallel mechanisms with three degrees of freedom is proposed in this paper. Based on the actuation wrench screw theory, the mathematical model mapping the input and output velocity vector space of the fully-decoupled 2R1T parallel mechanism is established. The actuation wrench screws and the actuated twist screws of the corresponding branches are derived according to the mathematic model. The forms of the unactuated screws are determined in terms of the reciprocal product theory. Structural synthesis of the branch chains is realized. Then type synthesis of parallel mechanisms is completed as well and lots of novel mechanisms are obtained. Finally, a 2RUPU-PU parallel mechanism synthesized is taken as an example to analyze its mobility and kinematics. Results show that the mechanism has two-rotational and onetranslational degrees of freedom and its Jacobian matrix is a diagonal matrix, i.e., it has the fully-decoupled kinematic characteristics. Therefore, the method proposed is correct and effective to synthesize the fully-decoupled 2R1T parallel mechanisms.

Workspace and Structural Parameter Analysis for a Novel 3-PRS Parallel Mechanism

Fuwei Sun,Junwei Zhao,Guoqiang Chen 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.12

The working space is one of the important indexes to measure the working capability of parallel mechanism. In this paper, the working space of a new type of 3-PRS parallel mechanism is studied. In the beginning, a novel 3-PRS parallel mechanism is proposed with the kinematics analyzed, and then the working space and volume are obtained by search algorithm, and the working space is drawn using MATLAB. Finally, the influence of the structural parameters on the working space is discussed, which provide theoretical basis for parameter optimization.

4족 병렬기구 보행로봇의 능수능란성에 관한 연구

김치효(Chi Hyo Kim),김성주(Sung Joo Kim),박근우(Kun Woo Park),김태성(Tae Sung Kim),이민기(Min Ki Lee) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10

This paper analyzes the dexterity of a four legged parallel walking robot. Topology design is conducted for a leg mechanism composed of four legs, base and ground, which constitute a redundant parallel mechanism. This mechanism is subdivided to four sub-mechanism composed of three legs. A motor vector is adopted to determine the 6x8 Jacobian of the redundant parallel mechanism and the 6x6 Jacobian of the sub-mechanisms, respectively. The condition number of the Jacobian matrices is used as an index to measure a dexterity. We analyze the condition numbers of the Jacobians over the positional walking space and the orientational walking space. The analysis shows that a sub-mechanism has lots of singularities within workspace but they are removed by a redundant parallel mechanism improving a dexterity. From the results, we can propose a parallel typed walking robot to enlarge walking space and stability region. The robot is designed by inserting an intermediate mechanism between upper and lower leg mechanisms. The robot is reasonably small so that it can climb from a floor to a wall.

Design and Analysis of Decoupled Parallel Mechanism with Redundant Actuator

김선호,김선호,전동수,신현표,인우성,김종원 한국정밀공학회 2009 International Journal of Precision Engineering and Vol. No.

This paper presents a redundantly actuated six degrees-of-freedom parallel kinematic mechanism with a partially decoupled architecture in its rotational motion. This mechanism is developed to eliminate kinematic complexity of original Eclipse-II known as a redundant parallel mechanism. Since the original Eclipse-II mechanism use kinematic redundancy of parallel mechanism to achieve an advantage in enlarging the workspace of the system, it needs a motion planning algorithm to choose the specific control inputs to determine the desired motion trajectory. This motion planning algorithm causes difficulty in achieving real-time control performance due to its structural complexity. However the redundant parallel mechanism presented in this paper is a redundant parallel mechanism with partially decoupled architecture in its rotational motion. Therefore modified Eclipse-II redundant parallel mechanism can realize effective real-time control performances and continuous 360-degree rotational motion in any direction of the moving platform with six degrees of freedom.

Definition of Linearly Dependent Screws in Singularity Configurations of Parallel Mechanisms and Experimental based on Computing of the System

Le Hoai Quoc,Nguyen Minh Thanh 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10

This paper examined the parallel mechanisms such as Stewart-Gough platform, for which an algorithm for determining the groups of linearly dependent screws that arise in singular condition. The algorithms to determine the model of mechanism take into account singularities configuration based on screw theory are proposed, the criterion of closeness to singularity is determined, the basic impact modeling results of parallel mechanisms. The research results on issues of singular condition of the parallel mechanism, which uses screw theory and Plucker coordinates. The experimental based on computation and determining the parameters of kinematic, dynamics and simulation for the control parallel mechanisms are considered. Speaking of which resolved the relations velocity, acceleration between the moving platform with the legs in the application; and relationship between external forces acting on the moving platform with forces on the legs of the system.

Screws on the Relative Parallel Mechanisms

Le Hoai Quoc,Nguyen Minh Thanh,Victor Glazunov,Aleksey Lastochkin 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10

In this paper, we consider screws on the relative parallel mechanisms with three parallel kinematic chains. The analysis of these mechanisms is carried out by means of screw theory. This approach allows avoiding satisfied equations by singularity analysis of mechanisms. The number of degrees of freedom of relative mechanism device is the total degrees of freedom of its constituent mechanisms. This property allows us to achieve the required number of degrees of freedom, using simple mechanisms in construction. Thus, it is possible to reduce the mutual effect that the motors have on each other when the mechanisms are in motion, placing them on the base. As a result of this, we are able to determine the optimal parameters of such a mechanism with the help of theoretical calculation.

A Compliant Parallel Mechanism with Flexure-based Joint Chains for Two Translations

최기봉,이재종,김기홍,임형준 한국정밀공학회 2012 International Journal of Precision Engineering and Vol. No.

A compliant parallel mechanism for two translations is proposed and applied to a XY fine motion stage driven by piezo actuators. Four flexure-based prismatic-prismatic joint chains are arranged in four sides of a target platform to implement the compliant parallel mechanism. Among others, two are passive joint chains for only motion guidance, and the others are active joint chains for motion guidance merging the function of the displacement amplification of a piezo actuator. Due to the active joint chains, the proposed mechanism has more compact structure than the others which have the separated mechanisms of the motion guidance and the displacement amplification. In addition, the compliant mechanism has a monolithic structure not to be assembled. The compliant mechanism is designed, verified to satisfy some design constraints using Finite element Analysis, and then combined with piezo actuators and capacitance sensors. The characteristics and the performance of the piezo-driven compliant parallel mechanism are demonstrated by experiments.

A Compliant Parallel Mechanism with Flexure-based Joint Chains for Two Translations

Choi, Kee-Bong,Lee, Jae Jong,Kim, Gee Hong,Lim, Hyung Jun 한국정밀공학회 2012 International Journal of Precision Engineering and Vol.13 No.9

A compliant parallel mechanism for two translations is proposed and applied to a XY fine motion stage driven by piezo actuators. Four flexure-based prismatic-prismatic joint chains are arranged in four sides of a target platform to implement the compliant parallel mechanism. Among others, two are passive joint chains for only motion guidance, and the others are active joint chains for motion guidance merging the function of the displacement amplification of a piezo actuator. Due to the active joint chains, the proposed mechanism has more compact structure than the others which have the separated mechanisms of the motion guidance and the displacement amplification. In addition, the compliant mechanism has a monolithic structure not to be assembled. The compliant mechanism is designed, verified to satisfy some design constraints using Finite element Analysis, and then combined with piezo actuators and capacitance sensors. The characteristics and the performance of the piezo-driven compliant parallel mechanism are demonstrated by experiments.