Conceptual Design and Static Analysis of Novel Planar Spring-Loaded Cable-Loop-Driven Parallel Mechanisms

2012 ◽  
Vol 4 (2) ◽  
Author(s):  
Hanwei Liu ◽  
Clément Gosselin ◽  
Thierry Laliberté
Keyword(s):  
Numerical Simulations ◽  
Static Analysis ◽  
Conceptual Design ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Parallel Mechanisms ◽  
Design Issues ◽  
Two Degrees Of Freedom ◽  
Actuation Redundancy ◽  
Insight Into

Two novel architectures of planar spring-loaded cable-loop-driven parallel mechanisms that do not require actuation redundancy are introduced in this paper. In order to avoid redundancy in the cable-driven parallel mechanisms and require only N actuators to control N-DOF motion, a new spring-loaded cable-loop-driven mechanism is proposed. By attaching springs to the cable loops, two degrees of freedom can be controlled using only two actuators and spools are eliminated in this mechanism. Therefore, the control method can be simplified compared with conventional cable-driven mechanisms making use of spools and actuation redundancy. The mechanisms can be actuated using either linear sliders or rotary actuators driving the motion of a cable or belt loop. Kinematic and static analyses are presented for the new architectures. It is verified that the cables and springs can be kept in tension within a certain workspace. Results of numerical simulations are also given in order to provide insight into the design issues.

scholarly journals Torque Ripple Suppression of PMSM Based on Robust Two Degrees-of-Freedom Resonant Controller

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1015
Author(s):  
Mingfei Huang ◽  
Yongting Deng ◽  
Hongwen Li ◽  
Jing Liu ◽  
Meng Shao ◽  
...  
Keyword(s):  
Control Strategy ◽  
Measurement Errors ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Torque Ripple ◽  
Current Loop ◽  
Two Degrees Of Freedom ◽  
Robust Stability Analysis ◽  
Resonant Controller ◽  
Testing Environments

This paper concentrates on a robust resonant control strategy of a permanent magnet synchronous motor (PMSM) for electric drivers with model uncertainties and external disturbances to improve the control performance of the current loop. Firstly, to reduce the torque ripple of PMSM, the resonant controller with fractional order (FO) calculus is introduced. Then, a robust two degrees-of-freedom (Robust-TDOF) control strategy was designed based on the modified resonant controller. Finally, by combining the two control methods, this study proposes an enhanced Robust-TDOF regulation method, named as the robust two degrees-of-freedom resonant controller (Robust-TDOFR), to guarantee the robustness of model uncertainty and to further improve the performance with minimized periodic torque ripples. Meanwhile, a tuning method was constructed followed by stability and robust stability analysis. Furthermore, the proposed Robust-TDOFR control method was applied in the current loop of a PMSM to suppress the periodic current harmonics caused by non-ideal factors of inverter and current measurement errors. Finally, simulations and experiments were performed to validate our control strategy. The simulation and experimental results showed that the THDs (total harmonic distortion) of phase current decreased to a level of 0.69% and 5.79% in the two testing environments.

Conceptual Design of Gear Differentials for Automotive Vehicles

1994 ◽  
Vol 116 (2) ◽  
pp. 565-570 ◽  
Author(s):  
Hong-Sen Yan ◽  
Long-Chang Hsieh
Keyword(s):  
Conceptual Design ◽  
Degrees Of Freedom ◽  
Planetary Gear ◽  
Gear Train ◽  
Design Constraints ◽  
Two Degrees Of Freedom ◽  
Design Concepts ◽  
Planetary Gear Trains ◽  
Gear Trains ◽  
Gear Differential

An automotive gear differential is a joint-fractionated planetary gear train with two degrees-of-freedom. We summarize the characteristics of planetary gear trains and the design constraints of noncoupled automotive gear differentials to synthesize their corresponding kinematic graphs. Based on these graphs and the proposed respecializing process, we generate the atlas of design concepts for automotive gear differentials with any types of gear pairs. As a result, there are 4, 25, and 156 design concepts for five-, six-, and seven-bar automotive gear differentials, respectively.

scholarly journals Flatness-Based Control of a Two Degrees-of-Freedom Platform With Pneumatic Artificial Muscles

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
David Bou Saba ◽  
Paolo Massioni ◽  
Eric Bideaux ◽  
Xavier Brun
Keyword(s):  
Degrees Of Freedom ◽  
Control Method ◽  
Sliding Mode ◽  
Feedforward Control ◽  
Volume Ratio ◽  
Open Loop ◽  
Control Technique ◽  
Artificial Muscles ◽  
Two Degrees Of Freedom ◽  
Pneumatic Artificial Muscles

Pneumatic artificial muscles (PAMs) are an interesting type of actuators as they provide high power-to-weight and power-to-volume ratio. However, their efficient use requires very accurate control methods taking into account their complex and nonlinear dynamics. This paper considers a two degrees-of-freedom platform whose attitude is determined by three pneumatic muscles controlled by servovalves. An overactuation is present as three muscles are controlled for only two degrees-of-freedom. The contribution of this work is twofold. First, whereas most of the literature approaches the control of systems of similar nature with sliding mode control, we show that the platform can be controlled with the flatness-based approach. This method is a nonlinear open-loop controller. In addition, this approach is model-based, and it can be applied thanks to the accurate models of the muscles, the platform and the servovalves, experimentally developed. In addition to the flatness-based controller, which is mainly a feedforward control, a proportional-integral (PI) controller is added in order to overcome the modeling errors and to improve the control robustness. Second, we solve the overactuation of the platform by an adequate choice for the range of the efforts applied by the muscles. In this paper, we recall the basics of this control technique and then show how it is applied to the proposed experimental platform. At the end of the paper, the proposed approach is compared to the most commonly used control method, and its effectiveness is shown by means of experimental results.

Type Synthesis of Two Degrees-of-Freedom Rotational Parallel Mechanisms With a Fixed Center-of-Rotation Based on a Graphic Approach

2012 ◽  
Author(s):  
K. Wu ◽  
J. J. Yu ◽  
S. Z. Li ◽  
G. H. Zong ◽  
Xianwen Kong
Keyword(s):  
High Performance ◽  
Degrees Of Freedom ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Two Degrees Of Freedom ◽  
Center Of Rotation ◽  
Parasitic Motion ◽  
Performance Requirements ◽  
Rotary Stage ◽  
Fixed Center

Mechanisms usually have to be particularly designed to meet the high-performance requirements in terms of different applications. For instance, Two degrees of freedom (DOF) rotational parallel mechanisms (RPMs) with a fixed center-of-rotation can eliminate parasitic motion and could provide the rotary stage with excellent dynamic stability, good controllability and easy operation. Therefore, this paper mainly aims at synthesizing 2-DOF RPMs with fixed center-of-rotation, a class of special RPMs with potential excellent performances. A graphic approach based on freedom and constraint spaces is introduced firstly. The constraint spaces of a class of the existing 2-DOF RPMs are illustrated, and the corresponding type synthesis patterns are summarized by comparing the geometric properties of those spaces with the mechanism characteristic. After fully decomposing the four-dimensional constraint space into sub-constraint spaces, a general type synthesis procedure is proposed based on the freedom and constraint topology. Two novel 2-DOF RPMs with fixed center-of-rotation are constructed based on the proposed method and procedure. The proposed graphic approach proves to be effective and simple to synthesizing those parallel mechanisms with some special performance.

The Conceptual Design of Differential Mechanisms

2013 ◽  
Vol 284-287 ◽  
pp. 973-978
Author(s):  
Chia Chun Chu
Keyword(s):  
Conceptual Design ◽  
Design Process ◽  
Degrees Of Freedom ◽  
Geometric Constraints ◽  
The Other ◽  
Design Approach ◽  
Process Step ◽  
Two Degrees Of Freedom ◽  
Number Synthesis

The purpose of this paper is to present a design approach based on the geometric constraints of joints for synthesizing differential mechanisms with two degrees-of-freedom, including some mechanisms with the same functions but distinct structures. The concept of virtual axes is presented. And, there are five steps in the design process. Step 1 is to decide fundamental entities by the properties of existing mechanisms and the technique of number synthesis, and 10 suitable fundamental entities of differential mechanisms are available. Step 2 is to compose geometric constraints, and 14 items are obtained. Step 3 is to compose links, and 15 items are derived. Step 4 is to assign fixed constraints for inputs or outputs, and 15 results are found. The final step is to particularize the obtained events by the properties of existing mechanisms and the structures of fundamental entities. As a result, 8 feasible results for differential mechanisms with two degrees-of-freedom and two basic loops are obtained in which 2 are existing designs and the other 6 are novel.

scholarly journals Turning characteristics of biomimetic robotic fish driven by two degrees of freedom of pectoral fins and flexible body/caudal fin

2018 ◽  
Vol 15 (1) ◽  
pp. 172988141774995 ◽  
Author(s):  
Zonggang Li ◽  
Liming Ge ◽  
Weiqiang Xu ◽  
Yajiang Du
Keyword(s):  
Numerical Simulations ◽  
Degrees Of Freedom ◽  
Robotic Fish ◽  
Flexible Body ◽  
Caudal Fin ◽  
Two Degrees Of Freedom ◽  
Pectoral Fins ◽  
Turn On ◽  
Biomimetic Robotic Fish ◽  
Two Degree Of Freedom

This article considers the turning characteristics of robotic fish with two-degree-of-freedom pectoral fins and flexible body/caudal fin. The hydrodynamics are first established for three cases propelled by both sides of pectoral fins, flexible body/caudal fin, and composite of them. Then, the turning characteristics of such three cases are analyzed by numerical simulations and experiments. The results show that if robotic fish is cooperatively propelled by pectoral fins and flexible body, it can obtain the fast turning speed and the average turning speed is up to 0.6 rad s−1. The smallest turning speed is achieved as robotic fish is only propelled by pectoral fins; however, it can turn on the spot in this case. The presented results provide the more abundant ways of turning, the better maneuverability, and the higher turning speed for the proposed robotic fish.

scholarly journals Central pattern generator–based coupling control method for synchronously controlling the two-degrees-of-freedom robot

2019 ◽  
Vol 103 (1) ◽  
pp. 003685041987773
Author(s):  
Qiang Fu ◽  
Tianhong Luo ◽  
Chunpeng Pan ◽  
Guoguo Wu
Keyword(s):  
Central Pattern Generator ◽  
Degrees Of Freedom ◽  
Control Method ◽  
Coupling Parameter ◽  
Pattern Generator ◽  
Rhythmic Pattern ◽  
Motion Pattern ◽  
Two Degrees Of Freedom ◽  
Synchronous Control ◽  
Real Time Simulations

Synchronous control is a fundamental and significant problem for controlling a multi-joint robot. In this article, by applying two coupled Rayleigh oscillators as the referred central pattern generator models for the two joints of a two-degrees-of-freedom robot, the central pattern generator–based coupling control method is proposed for controlling the two-degrees-of-freedom robot’s joints. On these bases, the co-simulation model of the two-degrees-of-freedom robot with the proposed central pattern generator–based coupling control method is established via ADAMS and MATLAB/Simulink, and the performance of the central pattern generator–based coupling control method on synchronizing two motions of two-degrees-of-freedom robot’s joints is numerically simulated. Furthermore, the experimental setup of a two-degrees-of-freedom robot is established based on the real-time simulations system via the proposed central pattern generator–based coupling control method. And experiments are carried out on the established setup. Simulations and experimental results show that the phase of the controlled two-degrees-of-freedom robot’s joints is mutual locked to other, and their motion pattern can be adjusted through the coupling parameter in the central pattern generator–based coupling control method. In conclusion, the proposed central pattern generator–based coupling control method can control the two-degrees-of-freedom robot’s joints to produce the coordinated motions and adjust the rhythmic pattern of the two-degrees-of-freedom robot.

A Planar Spring-Loaded Cable-Loop-Driven Parallel Mechanism

2010 ◽  
Author(s):  
Hanwei Liu ◽  
Cle´ment Gosselin ◽  
Thierry Laliberte´
Keyword(s):  
Numerical Simulations ◽  
Inverse Kinematics ◽  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Static Equilibrium ◽  
Equilibrium Equations ◽  
Two Degrees Of Freedom

A novel architecture of planar spring-loaded cable-loop-driven parallel mechanism is introduced in this paper. By attaching springs to the cable loops, two degrees of freedom can be controlled using only two actuators. In this mechanism, spools are eliminated. Therefore, it is expected that the accuracy of this mechanism is improved compared with conventional cable-driven mechanisms making use of spools. The mechanism can be actuated using either linear sliders or rotary actuators driving the motion of a cable or belt. This paper presents the inverse kinematics and the static equilibrium equations for the new architecture. It is verified that the cables and the springs can be kept in tension within the workspace. Results of numerical simulations are also given.

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