Biped 4-UPU Parallel Mechanism

2017 ◽  
Author(s):  
Zhihuai Miao ◽  
Yan’an Yao ◽  
Xianwen Kong ◽  
Bing Li
Keyword(s):  
Parallel Mechanism ◽  
Biped Robot ◽  
Singularity Analysis ◽  
Actuation Redundancy ◽  
Rugged Terrain ◽  
Motion Modes ◽  
Physical Prototype ◽  
Pass Through ◽  
Serial Chains ◽  
Actuation Method

A novel biped robot based on a 4-UPU (universal-prismatic-universal) parallel mechanism with actuation redundancy is presented. The biped robot consists of two platforms and four UPU serial chains as limbs. The actuation method of the mechanism is determined based on the mobility and singularity analysis. The singular positions of the mechanism are identified and then eliminated using a redundant actuator. To meet different requirements, the multiple motion modes of the robot are discussed and simulated in the gait analysis. Moreover, the robot has special gaits for reset and self-rescue if overturned. Kinematic analysis of the mechanism and walking stability analysis are carried out in detail. Physical prototype experiments indicate that the proposed biped robot is feasible. Through properly planning the motion modes, the biped robot can quickly pass through rugged terrain containing slopes and obstacles.

scholarly journals Optimum Seeking of Redundant Actuators for M-RCM 3-UPU Parallel Mechanism

2020 ◽  
Author(s):  
Chen Zhao ◽  
Jingke Song ◽  
Xuechan Chen ◽  
Ziming Chen ◽  
Huafeng Ding
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Singularity Analysis ◽  
Universal Joint ◽  
Prismatic Joint ◽  
Transmission Index ◽  
Redundant Actuators ◽  
Force Transmissibility ◽  
Singular Configuration

Abstract This paper focuses on a 2R1T 3-UPU (U for universal joint and P for prismatic joint) parallel mechanism (PM) with two rotational and one translational (2R1T) degrees of freedom (DOFs) and the ability of multiple remote centers of motion (M-RCM). The singularity analysis based on the indexes of motion/force transmissibility and constraint shows that this PM has transmission singularity, constraint singularity, mixed singularity and limb singularity. To solve these singularproblems, the quantifiable redundancy transmission index (RTI) and the redundancy constraint index (RCI) are proposed for optimum seeking of redundant actuators for this PM. Then the appropriate redundant actuators are selected and the working scheme for redundant actuators near the corresponding singular configuration are given to help the PM go through the singularity.

Type synthesis of 2R2T parallel mechanisms based on motion equivalent chain method

2014 ◽  
Vol 228 (17) ◽  
pp. 3209-3217 ◽  
Author(s):  
Wei Ye ◽  
Yuefa Fang ◽  
Sheng Guo ◽  
Haibo Qu
Keyword(s):  
Parallel Mechanism ◽  
Screw Theory ◽  
Parallel Mechanisms ◽  
Motion Pattern ◽  
Type Synthesis ◽  
Constraint Force ◽  
Single Loop ◽  
Loop Chain ◽  
Serial Chains

In this paper, the motion equivalent chain method is proposed and then applied to the type synthesis of a class of 2R2T parallel mechanism. The equivalent serial chains are synthesized for a specific 2R2T motion pattern based on screw theory. Feasible limb structures that provide a constraint couple and a constraint force are enumerated according to the reciprocity of the twist and wrench systems. Several motion equivalent single loop chains are constructed with the equivalent serial chains. Using motion equivalent single loop chains to replace the equivalent serial chains, a class of 2R2T parallel mechanisms is obtained based on the foundation of motion equivalent single loop chain structures.

Research on the Configurations and Singularity of Serial-Parallel Mechanism

2011 ◽  
Vol 393-395 ◽  
pp. 265-268
Author(s):  
Jian Guo Luo ◽  
Mao Yan He
Keyword(s):  
Parallel Mechanism ◽  
Parallel Manipulator ◽  
Synthesis Method ◽  
Singularity Analysis ◽  
Degree Of Freedom ◽  
Spatial Mobility

Methods to analysis the DOF(degree of freedom) and singularity of pure serial and pure parallel manipulator, which can not be used to the serial-parallel manipulator directly, three type of practical topological units and one type of virtual topological unit adopted, Synthesis method of topological dimensionality of the spatial mobility of each topological unit integrated together, architectures of serial-paralle mechanism discussed, also the formula and process of its topological dimensionality of spatial mobility presented, singularity analysis of serial-parallel mechanism can be carried out based on the forgoing results.

Design of a new gravity balanced parallel mechanism with Schönflies motion

2016 ◽  
Vol 230 (17) ◽  
pp. 3111-3134 ◽  
Author(s):  
Long Kang ◽  
Se-Min Oh ◽  
Wheekuk Kim ◽  
Byung-Ju Yi
Keyword(s):  
Parallel Mechanism ◽  
Screw Theory ◽  
Singularity Analysis ◽  
Force Transmission ◽  
Kinematic Modeling ◽  
Potential Applications ◽  
Structure Description ◽  
Grassmann Line Geometry ◽  
Schönflies Motion ◽  
Forward Kinematic

In this paper, a new gravity-balanced 3T1R parallel mechanism is addressed. Firstly, structure description, inverse and forward kinematic modeling are performed in detail. Secondly, Jacobian derivation based on screw theory and singularity analysis using Grassmann Line Geometry is performed, and then optimal kinematic design with respect to workspace size, kinematic isotropy and maximum force transmission ratio are conducted. Thirdly, the gravity balancing design using both counterweights and springs is proposed and a prototype of this mechanism is also presented. Results of analysis show that the proposed mechanism has quite a few potential applications.

A class of reconfigurable parallel mechanisms with five-bar metamorphic linkage

2016 ◽  
Vol 231 (11) ◽  
pp. 2089-2099 ◽  
Author(s):  
Chunxu Tian ◽  
Yuefa Fang ◽  
Sheng Guo ◽  
Haibo Qu
Keyword(s):  
Potential Application ◽  
Degrees Of Freedom ◽  
Screw Theory ◽  
Parallel Mechanisms ◽  
Constraint Force ◽  
Motion Modes ◽  
Moving Platform ◽  
Five Phases ◽  
Serial Chains

This paper presents a planar five-bar metamorphic linkage which has five phases resulting from locking of motors. Reconfigurable limbs are constructed by integrating the five-bar metamorphic linage as sub-chains. The branch transition of metamorphic linkage is analyzed. By adding appropriate joints to the planer five-bar metamorphic linkage, reconfigurable limbs whose constraint can switch among no constraint, a constrained force and a constrained couple are obtained. Serial limb structures that can provide a constraint force and a constraint couple are synthesized based on screw theory. Reconfigurable limbs that have five configurations associated with the five phases of the five-bar metamorphic linkage are assembled with 4-DOF (degrees-of-freedom) serial chains. A class of reconfigurable parallel mechanisms is derived by connecting the moving platform to the base with three identical kinematic limbs. These parallel mechanisms can perform various output motion modes such as 3T, 3R, 2T1R, 1T2R, 3T1R, 2T2R, 1T3R, 2T3R, 3T2R and 3T3R. Finally, the potential application of the proposed mechanisms is analyzed and conclusions are drawn.

Design of a Novel Statically Balanced Mechanism for Laparoscope Holders With Decoupled Positioning and Orientating Manipulation

2014 ◽  
Author(s):  
Chin-Hsing Kuo ◽  
Shao-Jung Lai
Keyword(s):  
Parallel Mechanism ◽  
Design Procedure ◽  
Static Balance ◽  
Cad Model ◽  
End Effector ◽  
Surgical Incision ◽  
Physical Prototype ◽  
Position And Orientation ◽  
Insertion Length ◽  
Kinematic Properties

This paper presents a novel mechanism concept of laparoscope holders used for minimally invasive surgery (MIS). The mechanism is made of a parallelogram linkage and a parallel mechanism, which respectively serve as a robotic positioning arm and an orientating wrist of the holder. Due to its special geometry, the mechanism possesses several interesting kinematic properties. First, the laparoscope, which is held by the end-effector, can illustrate a remote center-of-motion (RCM) kinematics at the surgical incision point. Second, the position of the RCM point is solely defined by the parallelogram, whereas the orientation and insertion length of the laparoscope are governed by the parallel mechanism. Such an arrangement suggests a decoupled positioning and orientating manipulation for the holder, which is clinically helpful in laparoscopic MIS. Third, the overall mechanism including the parallelogram linkage and the parallel mechanism can be perfectly statically balanced at any configuration within the workspaces by using common linear springs. In other words, no electrical actuation or mechanical locks are required for making the laparoscope rest at any position and orientation. The design procedure for static balancing is detailed in the paper, and the theoretically perfect static balance of the mechanism is verified by a numerical example and computer simulation. Furthermore, a CAD model of the holder is constructed for evaluating its workspaces and a physical prototype is built up and tested. As a result, the prototyped holder is fully statically balanced within a sufficient workspace for practical MIS environment.

Design of a Novel Statically Balanced Mechanism for Laparoscope Holders With Decoupled Positioning and Orientating Manipulation

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Chin-Hsing Kuo ◽  
Shao-Jung Lai
Keyword(s):  
Computer Aided Design ◽  
Parallel Mechanism ◽  
Design Procedure ◽  
Theoretical Formulation ◽  
Surgical Incision ◽  
Total Potential ◽  
Physical Prototype ◽  
Aided Design ◽  
Insertion Length ◽  
Kinematic Properties

This paper presents a novel mechanism concept of laparoscope holders used for minimally invasive surgery (MIS). The mechanism is made of a parallelogram linkage and a parallel mechanism, which, respectively, serve as a robotic positioning arm and an orientating wrist of the holder. Due to its special geometry, the mechanism possesses several interesting kinematic properties. First, the laparoscope, which is held by the end-effector, can illustrate a remote center-of-motion (RCM) kinematics at the surgical incision point. Second, the position of the RCM point is solely defined by the parallelogram, whereas the orientation and insertion length of the laparoscope are governed by the parallel mechanism. Such an arrangement suggests a decoupled positioning and orientating manipulation for the holder, which is clinically helpful in laparoscopic MIS. Third, the overall mechanism including the parallelogram linkage and the parallel mechanism can be statically balanced at any configuration within the workspaces by using common linear springs. In other words, no electrical actuation or mechanical locks are required for making the laparoscope rest at any position and orientation. The design procedure for static balancing is detailed in the paper, and the theoretical formulation of the statically balanced mechanism is verified by a numerical example and computer simulation. The computer-aided design (CAD) model of the holder is constructed for evaluating its workspace and a physical prototype using commercial springs is built up and tested. It shows that the prototype that uses nonideal (commercial) springs can be statically balanced within the overall workspace, since the shortage/overshoot of the potential energy in the positioning mechanism and orientating mechanism, which are theoretically 6.8% and 5.1% of their total potential energies in maximum, are fully compensated by the friction effect.

Influence Coefficients and Singularity Analysis of a Novel 3-UPU Parallel Mechanism

2017 ◽  
Author(s):  
Ziming Chen ◽  
Dongliang Cheng ◽  
Yang Zhang ◽  
Zhiwei Yang ◽  
Jin Zhou
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Model Simulation ◽  
Hessian Matrix ◽  
Symmetry Plane ◽  
Coefficient Matrix ◽  
Singularity Analysis ◽  
Influence Coefficient ◽  
Parasitic Motion ◽  
Moving Platform

A novel 3-UPU parallel mechanism with two rotational and one translational (2R1T) degrees of freedom (DOFs) is analyzed in this paper. The base and moving platform of this mechanism are always symmetric about a middle symmetry plane. The moving platform can rotate continuously about any axis on the middle symmetry plane, so there exists no parasitic motion during the rotation. Using the kinematic influence coefficient theory and the imaginary mechanism method, the first and second order influence coefficient matrix (namely Jacobian matrix and Hessian matrix) of this mechanism are derived. The relations between the velocity and acceleration of the moving platform and the actuated links are obtained. In order to verify the correctness of the theory, two numerical examples are enumerated and varified by the 3D model simulation. The singularities of this mechanism is discussed and the singular configurations of the mechanism, including one kind of limb singularity and two kinds of platform singularities, are obtained.

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