Reconstruction Designs of the Lost Structures of the Antikythera Mechanism With Two Degrees of Freedom

2014 ◽  
Vol 6 (3) ◽  
Author(s):  
Jian-Liang Lin ◽  
Hong-Sen Yan
Keyword(s):  
Degrees Of Freedom ◽  
Planetary Motion ◽  
Mechanism Analysis ◽  
Two Degrees Of Freedom ◽  
Design Concepts ◽  
Astronomical Instruments ◽  
Solar Motion ◽  
Celestial Bodies ◽  
Astronomical Instrument ◽  
Existing Structure

The Antikythera mechanism is an ancient astronomical instrument with various functions to indicate the date of the Egyptian calendar, display the motions of celestial bodies, calculate astronomical periods, and predict eclipse events. However, the portions of the mechanism that have been excavated do not completely support its functions. In particular, the structures corresponding to the demonstration of solar and planetary motions have been lost. This paper presents a systematic reconstruction of design concepts for the lost structures with two degrees of freedom. According to the investigations of existing structure and other ancient astronomical instruments, design concepts with two degrees of freedom are generated, and three possible double-input conditions are identified. Based on a mechanism analysis, two types of reconstruction designs are developed: five-bar mechanisms with six joints and six-bar mechanisms with eight joints. Design constraints were determined in accordance with the historical literature and existing designs. Then, by applying the concepts of generalization and specialization, as well as the input conditions and manufacturing process, three, four, and seven feasible reconstruction designs are synthesized for the solar motion, inferior planetary motion, and superior planetary motion, respectively. In addition, relations for the teeth calculations are derived for detail designs.

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.

Design and Singularity Analysis for Nine-Bar Mechanism of Three Crank Hybrid Driven

2014 ◽  
Vol 496-500 ◽  
pp. 781-784
Author(s):  
Sheng Tao Song ◽  
Rui Qin Li ◽  
Yan Gao ◽  
Da Hai Li
Keyword(s):  
Mechanical Properties ◽  
Degrees Of Freedom ◽  
Singularity Analysis ◽  
Mechanism Analysis ◽  
Analysis Method ◽  
Loop Analysis ◽  
Two Degrees Of Freedom ◽  
Long Rod ◽  
Existence Conditions

With two degrees of freedom five-bar linkage as the foundation, carry on the multiple loop coupling, built three crank controllable nine bar mechanism similar to that of the crank slider pressing, which can meet the controlled flexible output, and conform to the mechanical properties of crank slider pressing mechanism. We use the loop analysis method to analyze the singularity of the mechanism. Analysis through two steps, first of all analysis on three crank existence conditions and the entire organization singularity, it is concluded that the condition of mechanism dont have singularity, and according to the singular condition carrying on research of singularity position, the long rod assembly condition is obtained.

Reconstruction Synthesis of the Lost Subsystem for the Planetary Motions of Antikythera Mechanism

2011 ◽  
Author(s):  
Hong-Sen Yan ◽  
Jian-Liang Lin
Keyword(s):  
Planetary Motion ◽  
Mechanism Analysis ◽  
Design Concepts ◽  
Design Specifications ◽  
Solid Reconstruction ◽  
Time Period ◽  
Minimum Numbers ◽  
Planetary Theories

The mechanism for the planetary motions contained in the lost subsystem of Antikythera mechanism is a strict challenge of the reconstruction design and attracts many scholars’ attentions. In the modern time, Edmunds and Morgan, and Wright successively presented the design concepts, even the solid reconstruction models. To focus on the study of lost mechanisms, this work provides a systematic procedure of the reconstruction design to synthesize all feasible designs describing the planetary motion in the lost subsystem. And all synthesized designs agree with the science and technology standards of the subject’s time period. Based on the kinematic analysis of the planetary theories in the time of Antikythera mechanism, the anomaly planetary motions that could be demonstrated by a pin-in-slot device are completely understood. By the mechanism analysis and the design concept with the minimum numbers of the members, two types of the feasible topological structures and the corresponding design specifications are obtained: Type 1 is a four-bar mechanism with five joints; Type 2 is a five-bar mechanism with seven joints. In addition, the relations of the teeth for the inferior and superior planets are discussed in each possible combination of the planet gears. Moreover, through the study of the historical literature, the astronomical theories and the existing designs, the required design constraints are concluded further. For Type 1 and Type 2 reconstruction designs, one, the design by Edmunds and Morgan, and three feasible designs are respectively synthesized in accordance with the concepts of generalization and specialization. And all feasible designs are identified further for the suitable planets through the identifications of the input types. In conclusion, all generated designs are consistent with the scientific theories and techniques of the subject’s time period and match the surviving evidences.

The scientific bases of autocontrol with vibration phase for a resonance beating-vibration system with two degrees of freedom driven by debalances

1996 ◽  
Vol 18 (2) ◽  
pp. 43-48
Author(s):  
Tran Van Tuan ◽  
Do Sanh ◽  
Luu Duc Thach
Keyword(s):  
Degrees Of Freedom ◽  
Regulation System ◽  
Vibration System ◽  
Two Degrees Of Freedom ◽  
System Operating

In the paper it is introduced a method for studying dynamics of beating-vibrators by means of digital calculation with the help of the machine in accordance with the needs by the helps of an available auto regulation system operating with high reability.

scholarly journals Two Degrees of Freedom Slip Controller with Lateral Torque Distribution

2020 ◽  
Vol 53 (2) ◽  
pp. 14450-14455
Author(s):  
Wolfgang Degel ◽  
Stefan Lupberger ◽  
Dirk Odenthal ◽  
Naim Bajcinca
Keyword(s):  
Degrees Of Freedom ◽  
Torque Distribution ◽  
Two Degrees Of Freedom

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.

scholarly journals Analysis of Dynamic Response of a Two Degrees of Freedom (2-DOF) Ball Bearing Nonlinear Model

2021 ◽  
Vol 11 (2) ◽  
pp. 787
Author(s):  
Bartłomiej Ambrożkiewicz ◽  
Grzegorz Litak ◽  
Anthimos Georgiadis ◽  
Nicolas Meier ◽  
Alexander Gassner
Keyword(s):  
Mathematical Model ◽  
Degrees Of Freedom ◽  
Ball Bearing ◽  
Hertzian Contact ◽  
Two Degrees Of Freedom ◽  
Wide Range ◽  
Shape Errors ◽  
Nonlinear Features ◽  
Fourier Transform Phase ◽  
Hertzian Contact Theory

Often the input values used in mathematical models for rolling bearings are in a wide range, i.e., very small values of deformation and damping are confronted with big values of stiffness in the governing equations, which leads to miscalculations. This paper presents a two degrees of freedom (2-DOF) dimensionless mathematical model for ball bearings describing a procedure, which helps to scale the problem and reveal the relationships between dimensionless terms and their influence on the system’s response. The derived mathematical model considers nonlinear features as stiffness, damping, and radial internal clearance referring to the Hertzian contact theory. Further, important features are also taken into account including an external load, the eccentricity of the shaft-bearing system, and shape errors on the raceway investigating variable dynamics of the ball bearing. Analysis of obtained responses with Fast Fourier Transform, phase plots, orbit plots, and recurrences provide a rich source of information about the dynamics of the system and it helped to find the transition between the periodic and chaotic response and how it affects the topology of RPs and recurrence quantificators.

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