Parallel robots with configurable platforms: Fundamental aspects of a new class of robotic architectures

2015 ◽  
Vol 230 (3) ◽  
pp. 463-472 ◽  
Author(s):  
Patrice Lambert ◽  
Just L Herder
Keyword(s):  
Closed Loop ◽  
Jacobian Matrix ◽  
Dynamic Performance ◽  
Parallel Robots ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
New Class ◽  
Contact Points ◽  
The Subject ◽  
High Dynamic

This paper introduces general and fundamental aspects of a new class of parallel robots termed “parallel robots with configurable platforms”. The concept behind parallel mechanisms with configurable platforms is that the rigid link (non-configurable) end-effector is replaced by an additional closed-loop chain (the configurable platform). Some of the links of this closed loop are attached to the limbs so both the position and the configuration of the platform can be fully controlled from the motors located on the base. They retain the advantages of classical parallel robots, i.e. that all the motors are grounded on the base, while offering mechanical grasping capabilities via multiple contact points. Despite the few studies that have been done yet on the subject, the possible range of applications for this type of architecture is promising since it would be suitable for any application requiring both controlled grasping capabilities and high dynamic performance. This paper provides some preliminary results regarding the topology, mobility, overconstraints, Jacobian matrix, singularities and type synthesis of parallel robots with configurable platforms.

scholarly journals A New Method for Type Synthesis of 2R1T and 2T1R 3-DOF Redundant Actuated Parallel Mechanisms with Closed Loop Units

2020 ◽  
Vol 33 (1) ◽  
Author(s):  
Yongquan Li ◽  
Yang Zhang ◽  
Lijie Zhang
Keyword(s):  
Closed Loop ◽  
Screw Theory ◽  
Line Graph ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Allocation Criteria ◽  
Grassmann Line Geometry ◽  
Moving Platform ◽  
Atlas Method

Abstract The current type synthesis of the redundant actuated parallel mechanisms is adding active-actuated kinematic branches on the basis of the traditional parallel mechanisms, or using screw theory to perform multiple getting intersection and union to complete type synthesis. The number of redundant parallel mechanisms obtained by these two methods is limited. In this paper, based on Grassmann line geometry and Atlas method, a novel and effective method for type synthesis of redundant actuated parallel mechanisms (PMs) with closed-loop units is proposed. Firstly, the degree of freedom (DOF) and constraint line graph of the moving platform are determined successively, and redundant lines are added in constraint line graph to obtain the redundant constraint line graph and their equivalent line graph, and a branch constraint allocation scheme is formulated based on the allocation criteria. Secondly, a scheme is selected and redundant lines are added in the branch chains DOF graph to construct the redundant actuated branch chains with closed-loop units. Finally, the branch chains that meet the requirements of branch chains configuration criteria and F&C (degree of freedom & constraint) line graph are assembled. In this paper, two types of 2 rotational and 1 translational (2R1T) redundant actuated parallel mechanisms and one type of 2 translational and 1 rotational (2T1R) redundant actuated parallel mechanisms with few branches and closed-loop units were taken as examples, and 238, 92 and 15 new configurations were synthesized. All the mechanisms contain closed-loop units, and the mechanisms and the actuators both have good symmetry. Therefore, all the mechanisms have excellent comprehensive performance, in which the two rotational DOFs of the moving platform of 2R1T redundant actuated parallel mechanism can be independently controlled. The instantaneous analysis shows that all mechanisms are not instantaneous, which proves the feasibility and practicability of the method.

scholarly journals Design of Closed-Loop Parameters With High Dynamic Performance for Micro-Grating Accelerometer

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 151939-151947
Author(s):  
Hui Li ◽  
Keke Deng ◽  
Shan Gao ◽  
Lishuang Feng
Keyword(s):  
Closed Loop ◽  
Dynamic Performance ◽  
High Dynamic

scholarly journals Type synthesis and kinematics analysis of a family of three translational and one rotational pick-and-place parallel mechanisms with high rotational capability

2019 ◽  
Vol 11 (6) ◽  
pp. 168781401985307
Author(s):  
Xing Zhang ◽  
Dejun Mu ◽  
Yuze Liu ◽  
Jie Bi ◽  
Hongrui Wang
Keyword(s):  
Parallel Mechanism ◽  
Jacobian Matrix ◽  
Hessian Matrix ◽  
Parallel Mechanisms ◽  
Kinematics Analysis ◽  
Type Synthesis ◽  
Lie Group Theory ◽  
Revolute Joints ◽  
Pick And Place ◽  
Pick And Place Operation

This article proposes a family of spatial three translational and one rotational parallel mechanisms (PMs) for pick-and-place operation. Their features are one independent rotation of the mechanism with four identical limbs, which are provided by the four revolute joints on the moving platform. The rotational capability of the PMs has a range of at least 180°. This article focuses on the synthesis of the PMs and kinematics analysis of the 4- P(2-SS)R parallel mechanism. First, based on the Lie group theory, three parallelograms are used in designing the PMs. The limbs are listed and two types of three translational and one rotational PMs are synthesized. Then, a typical 4- P(2-SS)R PM is selected, the 6 × 6 Jacobian matrix and the 6 × 6 × 6 Hessian matrix of the mechanism are derived for solving the displacement, velocity, and acceleration of the mechanism. Finally, singularity configurations are disclosed from the 6 × 6 Jacobian matrix, and the workspace of the mechanism is provided to illustrate the high rotational capability.

The QuadroG Robot, a Parallel Robot With a Configurable Platform for Haptic Applications

2015 ◽  
Author(s):  
Salua Hamaza ◽  
Patrice Lambert ◽  
Marco Carricato ◽  
Just Herder
Keyword(s):  
Kinematic Analysis ◽  
Degrees Of Freedom ◽  
Closed Loop ◽  
Parallel Robot ◽  
Parallel Robots ◽  
End Effector ◽  
Contact Points ◽  
Loop Chain ◽  
End Effectors ◽  
4 Degrees Of Freedom

This paper explores the fundamentals of parallel robots with configurable platforms (PRCP), as well as the design and the kinematic analysis of those. The concept behind PRCP is that the rigid (non-configurable) end-effector is replaced by a closed-loop chain, the configurable platform. The use of a closed-loop chain allows the robot to interact with the environment from multiple contact points on the platform, which reflects the presence of multiple end-effectors. This results in a robot that successfully combines motion and grasping capabilities into a structure that provides an inherent high stiffness. This paper aims to introduce the QuadroG robot, a 4 degrees of freedom PRCP which finely merges planar motion together with grasping capabilities.

Type Synthesis of Parallel Mechanisms With a Constant Jacobian Matrix

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
Yanzhi Zhao ◽  
Yachao Cao ◽  
Xianwen Kong ◽  
Tieshi Zhao
Keyword(s):  
Jacobian Matrix ◽  
Screw Theory ◽  
Velocity Analysis ◽  
Parallel Mechanisms ◽  
Input Output ◽  
Type Synthesis ◽  
Analysis And Evaluation ◽  
Analysis Design ◽  
Moving Platform ◽  
And Control

Jacobian matrix plays a key role in the analysis, design, and control of robots. For example, it can be used for the performance analysis and evaluation of parallel mechanisms (PMs). However, the Jacobian matrix of a PM generally varies with the poses of the moving platform in the workspace. This leads to a nonconstant performance index of the PM. PMs with a constant Jacobian matrix have simple kinematics and are easy to design and control. This paper proposes a method for obtaining PMs with a constant Jacobian matrix. First, the criteria for detecting invariance of a Jacobian matrix are obtained based on the screw theory. An approach to the synthesis of PMs with a constant Jacobian matrix is then proposed. Using this approach, PMs with a constant Jacobian matrix are synthesized in two steps: the limb design and the combination of the limbs. Several PMs with a constant Jacobian matrix are obtained. In addition to the translational parallel mechanisms (TPMs) with a constant Jacobian matrix in the literature, the mixed-motion PMs whose moving platform can both translate and rotate with a constant Jacobian matrix are newly identified. The input/output velocity analysis of several PMs is presented to verify that Jacobian matrix of these PMs is constant.

Singularity Analysis of 5-RPRRR Parallel Mechanisms via Grassmann Line Geometry

2009 ◽  
Author(s):  
Mehdi Tale Masouleh ◽  
Cle´ment Gosselin
Keyword(s):  
Jacobian Matrix ◽  
Singularity Analysis ◽  
Degree Of Freedom ◽  
General Mechanism ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Line Geometry ◽  
Singular Configurations ◽  
Highly Nonlinear ◽  
Grassmann Line Geometry

This paper investigates the singular configurations of five-degree-of-freedom parallel mechanisms generating the 3T2R motion and comprising five identical legs of the RPUR type. The general mechanism was recently revealed by performing the type synthesis for symmetrical 5-DOF parallel mechanisms. In this study, some simplified designs are proposed for which the singular configurations can be predicted by means of the so-called Grassmann line geometry. This technique can be regarded as a powerful tool for analyzing the degeneration of the Plu¨cker screw set. The main focus of this contribution is to predict the actuation singularity, for a general and simplified design, without expanding the determinant of the inverse Jacobian matrix (actuated constraints system) which is highly nonlinear and difficult to analyze.

scholarly journals On the Optimal Design of Parallel Robots Taking Into Account Their Deformations and Natural Frequencies

2009 ◽  
Author(s):  
Se´bastien Briot ◽  
Anatol Pashkevich ◽  
Damien Chablat
Keyword(s):  
Optimal Design ◽  
Natural Frequencies ◽  
Jacobian Matrix ◽  
Parallel Robots ◽  
Drive System ◽  
Simplified Model ◽  
Simplified Models ◽  
Vibration Model ◽  
Dynamic Performances ◽  
High Dynamic

This paper discusses the utility of using simple stiffness and vibrations models, based on the Jacobian matrix of a manipulator and only the rigidity of the actuators, whenever its geometry is optimised. In many works, these simplified models are used to propose optimal design of robots. However, the elasticity of the drive system is often negligible in comparison with the elasticity of the elements, especially in applications where high dynamic performances are needed. Therefore, the use of such a simplified model may lead to the creation of robots with long legs, which will be submitted to large bending and twisting deformations. This paper presents an example of manipulator for which it is preferable to use a complete stiffness or vibration model to obtain the most suitable design and shows that the use of simplified models can lead to mechanisms with poorer rigidity.

scholarly journals Analysis and Optimization of Dynamic Measurement Precision of Fiber Optic Gyroscope

2013 ◽  
Vol 2013 ◽  
pp. 1-9
Author(s):  
Hui Li ◽  
Liyang Cui ◽  
Zhili Lin ◽  
Chunxi Zhang
Keyword(s):  
High Precision ◽  
Control Algorithm ◽  
Closed Loop ◽  
Fiber Optic ◽  
Dynamic Performance ◽  
Dynamic Measurement ◽  
Measurement Precision ◽  
Fiber Optic Gyroscope ◽  
Detection Circuit ◽  
High Dynamic

In order to improve the dynamic performance of high precision interferometer fiber optic gyroscope (IFOG), the influencing factors of the fast response characteristics are analyzed based on a proposed assistant design setup, and a high dynamic detection method is proposed to suppress the adverse effects of the key influencing factors. The assistant design platform is built by using the virtual instrument technology for IFOG, which can monitor the closed-loop state variables in real time for analyzing the influence of both the optical components and detection circuit on the dynamic performance of IFOG. The analysis results indicate that nonlinearity of optical Sagnac effect, optical parameter uncertainty, dynamic characteristics of internal modules and time delay of signal detection circuit are the major causes of dynamic performance deterioration, which can induce potential system instability in practical control systems. By taking all these factors into consideration, we design a robust control algorithm to realize the high dynamic closed-loop detection of IFOG. Finally, experiments show that the improved 0.01 deg/h high precision IFOG with the proposed control algorithm can achieve fast tracking and good dynamic measurement precision.

From Origami to a New Class of Centralized 3-DOF Parallel Mechanisms

2007 ◽  
Author(s):  
Ernesto Rodriguez Leal ◽  
Jian S. Dai
Keyword(s):  
Closed Form ◽  
Inverse Kinematics ◽  
Jacobian Matrix ◽  
Screw Theory ◽  
Geometric Constraints ◽  
Parallel Mechanisms ◽  
Closed Form Solutions ◽  
New Class ◽  
Workspace Analysis ◽  
Inverse Kinematics Problem

This paper applies the ‘technomimetics’ concept to generate a new class of parallel mechanisms inspired by origami folds. This new class of 3-DOF (Degree of Freedom) parallel mechanisms is constructed with 3-RPRP architecture. When the geometric constraints mentioned in this paper are applied, the mechanisms will be allowed to rotate around the x and y axes and translate vertically along the z axis, while the centre of the platform remains concentric to the centre of its base. This paper investigates both position and geometry of these mechanisms and identifies the closed form solutions for the inverse kinematics problem. The differential kinematical analysis is developed by deriving the Jacobian matrix through screw theory and the singularities are identified with workspace analysis. The paper ends with isotropic configuration analysis and illustrates the characteristics of the new mechanisms.

Type synthesis of spatial 3-DoF parallel mechanisms with planar sub-chains using revised digital topological graphs and arrays

Robotica ◽  
2015 ◽  
Vol 35 (2) ◽  
pp. 370-383 ◽  
Author(s):  
Yi Lu ◽  
Nijia Ye ◽  
Ling Ding
Keyword(s):  
Closed Loop ◽  
Degree Of Freedom ◽  
Digital Topology ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Simple Derivation ◽  
Topological Graphs ◽  
Topology Graph

SUMMARYType synthesis of spatial 3-DoF (degree of freedom) parallel mechanisms (PMs) with planar sub-chains is studied using the revised digital topology graph (r-DTGs) and arrays. First, many DTGs for type synthesis of spatial 3-DoF PMs are derived from their contracted graphs (CGs). Second, a complicated derivation of the DTG and an identification of an isomorphic DTG are transformed into a simple derivation of an array and an identification of an isomorphic array using a compiled program. Third, one or more spatial closed-loop chains in the derived DTGs are changed into the planar closed-loop chains by modifying digits marked in closed-loop chains, and the DTGs are transformed into the r-DTGs for the type synthesis of the spatial 3-DoF PMs with planar sub-chains. Finally, the 52 novel spatial 3-DoF PMs with the planar sub-chains are synthesized and verified by simulation mechanisms.

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