Ground Mobile Schatz Mechanism

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Chao Liu ◽  
Shun Yao ◽  
Hao Wang ◽  
Yan-An Yao
Keyword(s):  
Stability Analysis ◽  
Opposite Direction ◽  
Relative Position ◽  
Degree Of Freedom ◽  
Landing Point ◽  
Gait Planning ◽  
Straight Line ◽  
Constant Direction ◽  
Locomotion Analysis

We put forward a novel proposition that a mechanism can move in a constant direction and change its moving directions only by one actuator and construct a single-DOF (degree of freedom) ground mobile mechanism based on the well-known Schatz mechanism. This ground mobile Schatz mechanism has six links, one of which is designed as a spoke octahedron and an other one as a tail link. When the actuator rotates in one direction, the spoke octahedron can roll on the ground to let the ground mobile Schatz mechanism to move in a straight line pushed by the tail link. When the actuator rotates in the opposite direction, the tail link can be lifted to change its landing point and the relative position between it and the spoke octahedron, then the spoke octahedron can roll in another direction pushed by the tail link. In addition, it is also an untraditional application of the Schatz mechanism that it is used as a novel ground mobile mechanism. Locomotion analysis, gait planning and stability analysis are performed, respectively, and a prototype is developed and tested.

scholarly journals Generalized emergent dark energy: observational Hubble data constraints and stability analysis

2020 ◽  
Vol 497 (2) ◽  
pp. 1590-1602
Author(s):  
A Hernández-Almada ◽  
Genly Leon ◽  
Juan Magaña ◽  
Miguel A García-Aspeitia ◽  
V Motta
Keyword(s):  
Dark Energy ◽  
Stability Analysis ◽  
Degree Of Freedom ◽  
Dark Energy Density ◽  
Homogeneous Sample ◽  
The Standard Model ◽  
Yield Values ◽  
Data Constraints ◽  
The Universe ◽  
Universe Evolution

ABSTRACT Recently, a phenomenologically emergent dark energy (PEDE) model was presented with a dark energy density evolving as $\widetilde{\Omega }_{\rm {DE}}(z) = \Omega _{\rm {DE,0}}[ 1 - {\rm {tanh}}({\log }_{10}(1+z))]$, i.e. with no degree of freedom. Later on, a generalized model was proposed by adding one degree of freedom to the PEDE model, encoded in the parameter Δ. Motivated by these proposals, we constrain the parameter space ($h,\Omega _m^{(0)}$) and ($h,\Omega _m^{(0)}, \Delta$) for PEDE and generalized emergent dark energy (GEDE), respectively, by employing the most recent observational (non-)homogeneous and differential age Hubble data. Additionally, we reconstruct the deceleration and jerk parameters and estimate yield values at z = 0 of $q_0 = -0.784^{+0.028}_{-0.027}$ and $j_0 = 1.241^{+0.164}_{-0.149}$ for PEDE and $q_0 = -0.730^{+0.059}_{-0.067}$ and $j_0 = 1.293^{+0.194}_{-0.187}$ for GEDE using the homogeneous sample. We report values on the deceleration–acceleration transition redshift with those reported in the literature within 2σ CL. Furthermore, we perform a stability analysis of the PEDE and GEDE models to study the global evolution of the Universe around their critical points. Although the PEDE and GEDE dynamics are similar to the standard model, our stability analysis indicates that in both models there is an accelerated phase at early epochs of the Universe evolution.

scholarly journals A fast high-precision six-degree-of-freedom relative position sensor

2016 ◽  
Author(s):  
Gary B. Hughes ◽  
Van P. Macasaet ◽  
Janelle Griswold ◽  
Claudia A. Sison ◽  
Philip Lubin ◽  
...  
Keyword(s):  
High Precision ◽  
Relative Position ◽  
Degree Of Freedom ◽  
Position Sensor ◽  
Six Degree Of Freedom

Ground mobile Bennett mechanism

2019 ◽  
Vol 43 (1) ◽  
pp. 69-79 ◽  
Author(s):  
Zhirui Wang ◽  
Yan-an Yao ◽  
Chao Liu
Keyword(s):  
Weight Distribution ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Dynamic Analyses ◽  
Constant Direction ◽  
Moving Direction ◽  
Series Of Experiments

This paper presents a novel application of the well-known single degree of freedom Bennett mechanism. By optimizing the link’s shape and the weight distribution of the Bennett mechanism, we put forward a ground mobile mechanism that can move in a constant direction and change its moving direction with only one actuator. A type of tumbling gait is proposed and kinematic and dynamic analyses of the gait are carried out. Finally, a series of experiments are performed on a manufactured prototype. The results verify the tumbling gait and functionality of the mobile mechanism.

A Novel Two-Layer and Two-Loop Deployable Linkage With Accurate Vertical Straight-Line Motion

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Wen-ao Cao ◽  
De Zhang ◽  
Huafeng Ding
Keyword(s):  
Screw Theory ◽  
Kinematic Model ◽  
Degree Of Freedom ◽  
Kinematics Model ◽  
Vertical Straight Line ◽  
Straight Line ◽  
Structure Decomposition

Abstract This paper presents a novel two-layer and two-loop spatial deployable linkage which can only accurately output vertical straight-line motion. First, the degree-of-freedom (DOF) of the linkage is analyzed based on structure decomposition and screw theory, and the characteristic of the straight-line motion of the linkage is verified by checking the output twist of the end platform. Then, the kinematic model of the mechanism is established based on the conditions of the straight-line motion and the single DOF. Finally, several potentially typical applications of the linkage are exhibited. The straight-line linkage has relatively simple joint layouts and kinematics model and can be used as a deployable unit to construct some special deployable mechanisms.

The Evaluation of Agreement Between Dynamics of Electric Wheelchair and Human Behavior

2004 ◽  
Vol 16 (4) ◽  
pp. 434-442 ◽  
Author(s):  
Shigenobu Shimada ◽  
◽  
Kosei Ishimura ◽  
Mitsuo Wada ◽  
Keyword(s):  
Mathematical Model ◽  
Computer Simulation ◽  
Stability Analysis ◽  
Human Behavior ◽  
User Behavior ◽  
Electric Wheelchair ◽  
Straight Line ◽  
Almost All

We studied the problem of interaction of movement between the electric wheelchair and the user. Almost all current products have indexes such as roll stability and operability, but such indexes do not always agree with user behavior because such indexes are static. Another problem arises from the fact that the disagreement of movement causes uncontrollable situations and turnover of the wheelchairs. We evaluated wheelchairs that consider user behavior, first in an experiment to understand the cause of disagreement among users during movement by measuring straight line ands turning, then, based on this result, derived a mathematical model for disagreement in wheelchair motion. Computer simulation, showed that vibration occurred within certain parameters. We present simple roll stability analysis of wheelchairs turning. Simulation confirmed the viability of our proposals.

Coupled Nonlinear Barge Motions, Part II: Stochastic Models and Stability Analysis

2005 ◽  
Vol 127 (2) ◽  
pp. 83-95 ◽  
Author(s):  
Solomon C. S. Yim ◽  
Tongchate Nakhata ◽  
Erick T. Huang
Keyword(s):  
Stability Analysis ◽  
Stochastic Stability ◽  
First Passage Time ◽  
Passage Time ◽  
Computational Effort ◽  
Degree Of Freedom ◽  
Solution Technique ◽  
Roll Motion ◽  
Wave Elevation ◽  
Stochastic Stability Analysis

A computationally efficient quasi-two-degree-of-freedom (Q2DOF) stochastic model and a stability analysis of barges in random seas are presented in this paper. Based on the deterministic 2DOF coupled roll-heave model with high-degree polynomial approximation of restoring forces and moments developed in Part I, an attempt is made to further reduce the DOF of the model for efficient stochastic stability analysis by decoupling the heave effects on roll motion, resulting in a one-degree-of-freedom (1DOF) roll-only model. Using the Markov assumption, stochastic differential equations governing the evolution of probability densities of roll-heave and roll responses for the two low-DOF models are derived via the Fokker-Planck formulation. Numerical results of roll responses for the 2DOF and 1DOF models, using direct simulation in the time domain and the path integral solution technique in the probability domain, are compared to determine the effects of neglecting the influence of heave on roll motion and assess the relative computational efforts required. It is observed that the 1DOF model is computationally very efficient and the 2DOF model response predictions are quite accurate. However, the nonlinear roll-heave coupling is found to be significant and needs to be directly taken into account, rendering the 1DOF roll-only model inadequate for practical use. The 2DOF model is impractical for long-duration real-time response computation due to the insurmountable computational effort required. By taking advantage of the observed strong correlation between measured heave and wave elevation in the experimental results, an accurate and efficient Q2DOF model is developed by expressing the heave response in the 2DOF model as a function of wave elevation, thus reducing the effective DOF to unity. This Q2DOF model is essential as it reduces the computational effort by a factor of 10−5 compared to that of the 2DOF model, thus making practical stochastic analysis possible. A stochastic stability analysis of the barge under operational and survival sea states specified by the U.S. Navy is presented using the Q2DOF model based on first passage time formulation.

Energy-efficient bio-inspired gait planning and control for biped robot based on human locomotion analysis

2016 ◽  
Vol 13 (2) ◽  
pp. 271-282 ◽  
Author(s):  
Hongbo Zhu ◽  
Minzhou Luo ◽  
Tao Mei ◽  
Jianghai Zhao ◽  
Tao Li ◽  
...  
Keyword(s):  
Energy Efficient ◽  
Biped Robot ◽  
Human Locomotion ◽  
Gait Planning ◽  
Planning And Control ◽  
Locomotion Analysis ◽  
And Control
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