Design and Analysis of a Sixteen-Legged Vehicle With Reconfigurable Close-Chain Leg Mechanisms

2019 ◽  
Vol 11 (5) ◽  
Author(s):  
Jianxu Wu ◽  
Yan-an Yao ◽  
Yibin Li ◽  
Sen Wang ◽  
Qiang Ruan
Keyword(s):  
Sensitivity Analysis ◽  
Kinematic Analysis ◽  
Walking Speed ◽  
Gluteus Maximus ◽  
Degree Of Freedom ◽  
Probability Analysis ◽  
Dynamic Simulations ◽  
Closed Chain ◽  
Legged Vehicle ◽  
Leg Mechanisms

In order to exert the advantages of simplified control and integral rigidity, a novel 16-legged walking vehicle is proposed as a carrying platform based on closed-chain mechanisms. Considering the demand for mobility of one degree-of-freedom leg mechanism, we adopt the reconfigurable approach for trajectory flexibility. Serving as a walking module, the whole close-chain leg mechanism is designed to construct the walking vehicle. On the basis of kinematic analysis and sensitivity analysis, the reconfigurable leg with “gluteus maximus” is presented for increasing the obstacle-surmounting ability. In terms of the whole vehicle, the reconfiguration assignments and strategies are analyzed to satisfy the different climbing requirements. The obstacle-climbing capabilities of the legged units are evaluated through the probability analysis. In slope-climbing process, the supporting and the propelling regions for reconfiguration are discussed and obtained with two decision conditions. A series of dynamic simulations and experiments are performed to testify the walking stability, the walking speed, the steering performance, the terrain adaptability, and the obstacle-surmounting capability.

The Design of Looped-Synchronous Mechanism With Duplicated Spatial Assur-Groups

2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Xu Wang ◽  
Weizhong Guo
Keyword(s):  
Optimization Method ◽  
Degree Of Freedom ◽  
Transmission Ratio ◽  
Main Body ◽  
Prime Mover ◽  
Dynamic Simulations ◽  
Closed Chain ◽  
Stator Blade ◽  
Assur Group ◽  
Aero Engines

The looped-synchronous mechanism (LSM) is a special one degree-of-freedom (DOF) closed chain of transmission with a large number of duplicated units that synchronizes the motion of many output links. This kind of mechanism can be found in many applications such as stator blade adjusting mechanisms for various aero-engines. The LSMs are composed of a large number of links and joints and must be designed by specific means. Spatial Assur-group, which is a concept extended from traditional Assur-group(in planar scope), and usually with a little number of parts and joints, is used in this work to design LSM. First, based on the formula of DOF of spatial Assur-group, all possible combinations are listed and two feasible combinations are chosen as the main body of each unit of LSM, combining with a prime mover to meet the requirement to be inexpandable and adjustable. Second, the condition for transmission ratio of the used Assur-group to be 1 is distilled for being synchronous and looped under the situation that all units of LSM have the same topology. To meet the condition, the needed dimensional conditions are researched and mathematical deduction is used to figure out the possibilities. Third, after confirming that it is impossible to meet the condition strictly, an optimization method in the environment of Simulink is used to approach the condition as close as possible. Finally, numerical and dynamic simulations are carried out to verify the effectiveness of the mentioned methods.

Kinematic and Workspace Modelling of a 6-PUS Parallel Mechanism

2018 ◽  
Author(s):  
Jérôme Landuré ◽  
Clément Gosselin
Keyword(s):  
Kinematic Analysis ◽  
Parallel Mechanism ◽  
Inverse Kinematic ◽  
Degree Of Freedom ◽  
Accurate Description ◽  
Transmission Ratio ◽  
Inverse Kinematic Problem ◽  
Jacobian Matrices ◽  
Six Degree Of Freedom

This article presents the kinematic analysis of a six-degree-of-freedom six-legged parallel mechanism of the 6-PUS architecture. The inverse kinematic problem is recalled and the Jacobian matrices are derived. Then, an algorithm for the geometric determination of the workspace is presented, which yields a very fast and accurate description of the workspace of the mechanism. Singular boundaries and a transmission ratio index are then introduced and studied for a set of architectural parameters. The proposed analysis yields conceptual architectures whose properties can be adjusted to fit given applications.

scholarly journals Automated Generation of Linkage Loop Equations for Planar One Degree-of-Freedom Linkages, Demonstrated up to 8-Bar

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Brian E. Parrish ◽  
J. Michael McCarthy ◽  
David Eppstein
Keyword(s):  
Kinematic Analysis ◽  
Degree Of Freedom ◽  
Common Edge ◽  
Adjacency Graph ◽  
Automated Generation ◽  
Cycle Basis ◽  
Revolute Joints

In this paper, we present an algorithm that automatically creates the linkage loop equations for planar one degree of freedom, 1DOF, linkages of any topology with revolute joints, demonstrated up to 8 bar. The algorithm derives the linkage loop equations from the linkage adjacency graph by establishing a rooted cycle basis through a single common edge. Divergent and convergent loops are identified and used to establish the fixed angles of the ternary and higher links. Results demonstrate the automated generation of the linkage loop equations for the nine unique 6-bar linkages with ground-connected inputs that can be constructed from the five distinct 6-bar mechanisms, Watt I–II and Stephenson I–III. Results also automatically produced the loop equations for all 153 unique linkages with a ground-connected input that can be constructed from the 71 distinct 8-bar mechanisms. The resulting loop equations enable the automatic derivation of the Dixon determinant for linkage kinematic analysis of the position of every possible assembly configuration. The loop equations also enable the automatic derivation of the Jacobian for singularity evaluation and tracking of a particular assembly configuration over the desired range of input angles. The methodology provides the foundation for the automated configuration analysis of every topology and every assembly configuration of 1DOF linkages with revolute joints up to 8 bar. The methodology also provides a foundation for automated configuration analysis of 10-bar and higher linkages.

A Novel 3-DOF Parallel Robot and its Kinematic Analysis

2014 ◽  
Vol 607 ◽  
pp. 759-763
Author(s):  
Xiao Bo Liu ◽  
Xiao Dong Yuan ◽  
Xiao Feng Wei ◽  
Wei Ni
Keyword(s):  
Motion Control ◽  
Kinematic Analysis ◽  
Degrees Of Freedom ◽  
Parallel Robot ◽  
Degree Of Freedom ◽  
The Novel ◽  
Forward Displacement ◽  
Simulation Based ◽  
Simulation Results

This paper deals with the design and analysis of a novel and simple two-translation and one-rotation (3 degrees of freedom, 3-dof) mechanism for alignment. Firstly, degree of freedom of the parallel robot is solved based on the theory of screw. Secondly considering the demand of motion control, we have conducted the analysis on the 3-dof parallel robot, which includes inverse displacement, forward displacement, and simulation based on SolidWorks Motion. The simulation results indicate that the novel 3-dof robot is suitable for performing the required operations.

Forward/Reverse Velocity and Acceleration Analysis for a Class of Lower-Mobility Parallel Mechanisms

2006 ◽  
Vol 129 (4) ◽  
pp. 390-396 ◽  
Author(s):  
Si J. Zhu ◽  
Zhen Huang ◽  
Hua F. Ding
Keyword(s):  
Kinematic Analysis ◽  
Jacobian Matrix ◽  
Hessian Matrix ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Analysis Method ◽  
Rear Part ◽  
Lower Mobility ◽  
Acceleration Analysis

This paper proposes a novel kinematic analysis method for a class of lower-mobility mechanisms whose degree-of-freedom (DoF) equal the number of single-DoF kinematic pairs in each kinematic limb if all multi-DoF kinematic pairs are substituted by the single one. For such an N-DoF (N<6) mechanism, this method can build a square (N×N) Jacobian matrix and cubic (N×N×N) Hessian matrix. The formulas in this method for different parallel mechanisms have unified forms and consequently the method is convenient for programming. The more complicated the mechanism is (for instance, the mechanism has more kinematic limbs or pairs), the more effective the method is. In the rear part of the paper, mechanisms 5-DoF 3-R(CRR) and 5-DoF 3-(RRR)(RR) are analyzed as examples.

Kinematic sensitivity analysis of a novel micro-mechanism for displacement amplification

2018 ◽  
Vol 42 (4) ◽  
pp. 436-443 ◽  
Author(s):  
Sohail Iqbal ◽  
Afzaal Malik ◽  
Rana I Shakoor
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Modal Analysis ◽  
Geometric Parameters ◽  
Small Displacement ◽  
Extended Finite Element ◽  
Dynamic Simulations ◽  
Element Analysis ◽  
Amplification Mechanism ◽  
Kinematic Sensitivity

This research article presents the design and analysis of a displacement amplification mechanism based on a microelectromechanical system (MEMS). The mechanism, compared to generic displacement mechanisms, is smaller and capable of amplifying input displacement by a factor of 6.8. Finite element analysis (FEA) is performed with commercial software Intellisuite using the extended finite element method (XFEM) technique to verify the analytical results from mathematical models. Kinematic response and kinematic sensitivity analysis of the amplification mechanism are computationally carried out to predict the effect of different geometric parameters on the performance of the proposed mechanism. The analysis predicts that length and angle of flexure are the two key geometric parameters significantly affecting the amplification factor (AF), with length having a direct relationship and angle of flexure having an inverse relationship. A significant increase in the AF is seen for a flexure length up to 550 μm and angle below 5°. Based on the sensitivity analysis, the design is optimized, and geometric parameters are finalized. Modal analysis and dynamic simulations, including direct-integration transient and steady-state modal analysis, are performed on the mechanism under the application of 25 g. The mechanism can be integrated with any conventional actuating mechanism in a microsystem where the amplification of a small displacement at the output is desired.

Reverse Kinematic Analysis of the Spatial Six Axis Robotic Manipulator With Consecutive Joint Axes Parallel

2007 ◽  
Author(s):  
Javier Rolda´n Mckinley ◽  
Carl Crane ◽  
David B. Dooner
Keyword(s):  
Kinematic Analysis ◽  
Closed Loop ◽  
Degree Of Freedom ◽  
Repetitive Motion ◽  
Spatial Mechanism ◽  
Joint Axis ◽  
Specific Geometry ◽  
Noncircular Gears ◽  
Six Degree Of Freedom ◽  
The Given

This paper introduces a reconfigurable one degree-of-freedom spatial mechanism that can be applied to repetitive motion tasks. The concept is to incorporate five pairs of noncircular gears into a six degree-of-freedom closed-loop spatial chain. The gear pairs are designed based on the given mechanism parameters and the user defined motion specification of a coupler link of the mechanism. It is shown in the paper that planar gear pairs can be used if the spatial closed-loop chain is comprised of six pairs of parallel joint axes, i.e. the first joint axis is parallel to the second, the third is parallel to the fourth, …, and the eleventh is parallel to the twelfth. This paper presents the detailed reverse kinematic analysis of this specific geometry. A numerical example is presented.

Design of a High-Speed Spherical Four-Bar Mechanism for Use in a Motion Common in Assembly Processes

2007 ◽  
Author(s):  
Andrew P. Murray ◽  
Franc¸ois Pierrot
Keyword(s):  
Sensitivity Analysis ◽  
High Speed ◽  
Mechanical Design ◽  
Degree Of Freedom ◽  
Kinematic Synthesis ◽  
Control Scheme ◽  
Smooth Motion ◽  
Spherical Mechanism

In this paper, we present the mechanical design of a spherical four-bar mechanism for performing a motion common in manufacturing and assembly processes. The mechanism is designed to create, in a single, smooth motion, the combined rotation of a body by 90 degrees about one axis with a 90 degree rotation about an axis perpendicular to the first. A spherical four-bar mechanism is pursued as the basis for the design because the reorientation is produced mechanically rather than via a control scheme typical when higher degree of freedom systems are utilized. The design initiates with the kinematic synthesis of the spherical mechanism to guide a body through two orientations. The next step in the design is to refine the spherical fourbar based on manufacturing and operational concerns. As one of the challenges of utilizing these four-bars is tuning the starting and ending angle for the mechanism’s motion, a sensitivity analysis is performed to gauge the needed accuracy. Finally, there are details and a discussion of the proposed mechanical design.

Kinematic Analysis of Robotic Bevel-Gear Trains

1984 ◽  
Vol 106 (3) ◽  
pp. 371-375 ◽  
Author(s):  
F. Freudenstein ◽  
R. W. Longman ◽  
C.-K. Chen
Keyword(s):  
Kinematic Analysis ◽  
Industrial Robot ◽  
General Procedure ◽  
Bevel Gear ◽  
Degree Of Freedom ◽  
Gear Train ◽  
End Effector ◽  
Gear Trains ◽  
Three Degree Of Freedom

A general procedure has been developed for the kinematic analysis of complex bevel-gear trains in which the motion of the arm can be of mobility two or greater (i.e. the arm can rotate about two or more nonparallel, intersecting axes). The analysis of a three-degree-of-freedom gear train used in guiding the motion of the end effector of a recently developed industrial robot is described in detail.

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