Spring Parameters Design for the New Hydraulic Actuated Quadruped Robot

2014 ◽  
Vol 6 (2) ◽  
Author(s):  
Xianbao Chen ◽  
Feng Gao ◽  
Chenkun Qi ◽  
Xinghua Tian ◽  
Jiaqi Zhang
Keyword(s):  
Hydraulic System ◽  
Stance Phase ◽  
State Of The Art ◽  
Dynamic Performance ◽  
Weight Ratio ◽  
Quadruped Robot ◽  
Hydraulic Pressure ◽  
System Pressure ◽  
Pump Pressure ◽  
Very High

More and more state-of-the-art robots have employed hydraulic actuating systems. It has a high power-to-weight ratio. Robots with these actuators can bear more payloads and achieve highly dynamic performance. However, the energy consumption is also very high and the system is very complicated comparing to the electronic motor actuated robot. A lot of research has been done to save the energy. Among which the application of springs is one of the most commonly used methods. This paper presents another use of the spring to save the energy by reducing the hydraulic system pressure of a newly built robot called the “Baby Elephant.” The configuration of the spring is designed according to the leg mechanism. The spring gives an assist force in the stance phase of the leg and exerts a passive payload in the swing phase. The maximum cylinder force is then reduced so as to bring down the pump pressure. The energy to be saved depends on how much the hydraulic pressure can be reduced. In this paper, the Baby Elephant is briefly introduced, the design of the springs on saving the energy are described. Simulations and experiments are carried out to confirm the effect.

The Study on Optimal Matching of Power System of Hybrid Hydraulic TLT

2010 ◽  
Vol 97-101 ◽  
pp. 4403-4407
Author(s):  
Li Jun Zhao ◽  
Guo Jun Li ◽  
Ji Hai Jiang
Keyword(s):  
Hydraulic System ◽  
Dynamic Performance ◽  
Reference Value ◽  
Theory Analysis ◽  
Simulated Annealing Genetic Algorithm ◽  
System Pressure ◽  
Comprehensive Performance ◽  
Optimizing Model ◽  
Single Objective ◽  
System Program

According to the running characteristic of an aircraft tractor and the specificity of serve target, the hybrid hydraulic system program is proposed. In the use of Adopting Simulated Annealing Genetic Algorithm, for the demand of aircraft tractor’s system, the multi-objective is transformed to a single objective function of the automobile’s dynamic performance and fuel economy performance by using the linear weighted method. Then the mathematical optimizing model of the powertrain is established, through calculating, reasonable parameters are gotten. The analysis of the simulation results shows that the comprehensive performance of the automobile has been remarkably promoted. On the basis of previous work, the system pressure of different weight aircraft models of traction has been optimized in order to give full play to the vehicle's performance. The research has important reference value for the theory analysis of hybrid systems and engineering applications.

scholarly journals The Influence of Valve-Pump Weight Ratios on the Dynamic Response of Leaking Valve-Pump Parallel Control Hydraulic Systems

2018 ◽  
Vol 8 (7) ◽  
pp. 1201 ◽  
Author(s):  
Haigang Ding ◽  
Jiyun Zhao ◽  
Gang Cheng ◽  
Steve Wright ◽  
Yufeng Yao
Keyword(s):  
Dynamic Response ◽  
Hydraulic System ◽  
Weight Ratio ◽  
Open Loop ◽  
Hydraulic Systems ◽  
Variable Speed ◽  
Weight Factors ◽  
Wide Range ◽  
Parallel Control ◽  
Valve Control

A new leaking valve-pump parallel control (LVPC) oil hydraulic system is proposed to improve the performance of dynamic response of present variable speed pump control (VSPC) system, which is an oil hydraulic control system with saving energy. In the LVPC, a control valve is operating at leaking status, together with a variable speed pump, to regulate the system flow of hydraulic oil simultaneously. Therefore, the degree of valve control and pump control can be adjusted by regulating the valve-pump weight ratio. The LVPC system design, mathematical model development, system parameter and control performance analysis are carried out systematically followed by an experimental for validation process. Results have shown that after introducing the valve control, the total leakage coefficient increases significantly over a wide range with the operating point and this further increases damping ratios and reduces the velocity stiffness. As the valve-pump weight ratio determines the flow distribution between the valve and the pump and the weight factors of the valve and/or the pump controls determines the response speed of the LVPC system, thus if the weight factors are constrained properly, the LVPC system will eventually have a large synthetic open-loop gain and it will respond faster than the VSPC system. The LVPC will enrich the control schemes of oil hydraulic system and has potential value in application requiring of fast response.

scholarly journals In-House Developed Kr Estimator: Implemented to Analyze the Sensitivity of Relative Permeability Data to Variations in Wetting Phase Saturation

2011 ◽  
Vol 29 (6) ◽  
pp. 817-825 ◽  
Author(s):  
Muhammad Khurram Zahoor
Keyword(s):  
Porous Medium ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Relative Permeability ◽  
State Of The Art ◽  
Data Generation ◽  
Phase Saturation ◽  
Complex Models ◽  
Relative Permeability Curves ◽  
Very High

Reservoir surveillance always requires fast, unproblematic access and solution to different relative permeability models which have been developed from time to time. In addition, complex models sometimes require in-depth knowledge of mathematics for solution prior to use them for data generation. For this purpose, in-house software has been designed to generate rigorous relative permeability curves, with a provision to include users own relative permeability models, a part from built-in various relative permeability correlations. The developed software with state-of-the-art algorithms has been used to analyze the effect of variations in residual and maximum wetting phase saturation on relative permeability curves for a porous medium having very high non-uniformity in pore size distribution. To further increase the spectrum of the study, two relative permeability models, i.e., Pirson's correlation and Brooks and Corey model has been used and the obtained results show that the later model is more sensitive to such variations.

A GLANCE BEYOND THE STANDARD MODEL: LATEST RESULTS FROM THE MEG EXPERIMENT

2014 ◽  
Vol 35 ◽  
pp. 1460390
Author(s):  
SIMEONE DUSSONI
Keyword(s):  
Beyond Standard Model ◽  
Standard Model ◽  
High Intensity ◽  
State Of The Art ◽  
Branching Ratio ◽  
Beyond The Standard Model ◽  
Upper Limit ◽  
The Standard Model ◽  
Key Features ◽  
Very High

The MEG experiment started taking data in 2009 looking for the Standard Model suppressed decay μ → e + γ, which, if observed, can reveal Beyond Standard Model physics. It makes use of state-of-the art detectors optimized for operating in conditions of very high intensity, rejecting as much background as possible. The data taking ended August 2013 and an upgrade R&D is started to push the experimental sensitivity. The present upper limit on the decay Branching Ratio (BR) is presented, obtained with the subset of data from 2009 to 2011 run, together with a description of the key features of the upgraded detector.

Reinforcement Learning for Active Noise Control in a Hydraulic System

2021 ◽  
Vol 143 (6) ◽  
Author(s):  
Eric R. Anderson ◽  
Brian L. Steward
Keyword(s):  
Reinforcement Learning ◽  
Hydraulic System ◽  
Noise Control ◽  
Control Method ◽  
Active Noise Control ◽  
Operating Point ◽  
Hydraulic Pressure ◽  
Hydraulic Systems ◽  
Active Noise ◽  
Pressure Ripple

Abstract Hydraulic pressure ripple in a pump, as a result of converting rotational power to fluid power, continues to be a problem faced when developing hydraulic systems due to the resulting noise generated. In this paper, we present simulation results from leveraging an actor-critic reinforcement learning method as the control method for active noise control in a hydraulic system. The results demonstrate greater than 96%, 81%, and 61% pressure ripple reduction for the first, second, and third harmonics, respectively, in a single operating point test, along with the advantage of feed forward like control for high bandwidth response during dynamic changes in the operating point. It also demonstrates the disadvantage of long convergence times while the controller is effectively learning the optimal control policy. Additionally, this work demonstrates the ancillary benefit of the elimination of the injection of white noise for the purpose of system identification in the current state of the art.

scholarly journals DispHred: A Server to Predict pH-Dependent Order–Disorder Transitions in Intrinsically Disordered Proteins

2020 ◽  
Vol 21 (16) ◽  
pp. 5814 ◽  
Author(s):  
Jaime Santos ◽  
Valentín Iglesias ◽  
Carlos Pintado ◽  
Juan Santos-Suárez ◽  
Salvador Ventura
Keyword(s):  
Intrinsically Disordered Proteins ◽  
State Of The Art ◽  
Disordered Proteins ◽  
Protein Disorder ◽  
Net Charge ◽  
Intrinsically Disordered ◽  
Linear Boundary Condition ◽  
Natively Unfolded ◽  
Ph Dependent ◽  
Very High

The natively unfolded nature of intrinsically disordered proteins (IDPs) relies on several physicochemical principles, of which the balance between a low sequence hydrophobicity and a high net charge appears to be critical. Under this premise, it is well-known that disordered proteins populate a defined region of the charge–hydropathy (C–H) space and that a linear boundary condition is sufficient to distinguish between folded and disordered proteins, an approach widely applied for the prediction of protein disorder. Nevertheless, it is evident that the C–H relation of a protein is not unalterable but can be modulated by factors extrinsic to its sequence. Here, we applied a C–H-based analysis to develop a computational approach that evaluates sequence disorder as a function of pH, assuming that both protein net charge and hydrophobicity are dependent on pH solution. On that basis, we developed DispHred, the first pH-dependent predictor of protein disorder. Despite its simplicity, DispHred displays very high accuracy in identifying pH-induced order/disorder protein transitions. DispHred might be useful for diverse applications, from the analysis of conditionally disordered segments to the synthetic design of disorder tags for biotechnological applications. Importantly, since many disorder predictors use hydrophobicity as an input, the here developed framework can be implemented in other state-of-the-art algorithms.

scholarly journals Evaluating State-of-the-Art LEED-NCv4 in the U.S.

2020 ◽  
Vol 10 (3) ◽  
pp. 775
Author(s):  
Pushkar
Keyword(s):  
Environmental Quality ◽  
State Of The Art ◽  
Environmental Design ◽  
The Other ◽  
Indoor Environmental Quality ◽  
Water Efficiency ◽  
New Construction ◽  
Almost All ◽  
Very High ◽  
The U.S

To date, no empirical evidence has been published on the certification achievements of Leadership in Energy and Environmental Design for New Construction (LEED-NCv4) projects. Therefore, the aim of this study was to determine the trends in LEED-NCv4 Certified, Silver, Gold, and Platinum projects in the U.S. Boxplots were used to measure the consistency of achievement points in categories; Cliff’s δ was used to measure the effect size between possible points and achieved points in categories and credits. The findings show that (1) the categories Sustainable Sites and Energy and Atmosphere were well designed, with consistency increasing from level to level and almost all their credits achieving low–very high points; (2) the categories Water Efficiency and Indoor Environmental Quality showed an average design, and certification levels were found to be inconsistent across the projects and only approximately half of the credits achieved medium or high points, whereas the other half achieved low points; and (3) the categories Location and Transportation and Materials and Resources were the worst designed, with four certification levels found to be inconsistent across the projects and most of the credits achieved low points.

scholarly journals An Analysis of Smart Contracts Security Threats Alongside Existing Solutions

Entropy ◽  
2020 ◽  
Vol 22 (2) ◽  
pp. 203
Author(s):  
Antonio López Vivar ◽  
Alberto Turégano Castedo ◽  
Ana Lucila Sandoval Orozco ◽  
Luis Javier García Villalba
Keyword(s):  
Economic Impact ◽  
State Of The Art ◽  
Public Domain ◽  
Third Parties ◽  
The State ◽  
Security Threats ◽  
Smart Contracts ◽  
Holistic View ◽  
Security Challenges ◽  
Very High

Smart contracts have gained a lot of popularity in recent times as they are a very powerful tool for the development of decentralised and automatic applications in many fields without the need for intermediaries or trusted third parties. However, due to the decentralised nature of the blockchain on which they are based, a series of challenges have emerged related to vulnerabilities in their programming that, given their particularities, could have (and have already had) a very high economic impact. This article provides a holistic view of security challenges associated with smart contracts, as well as the state of the art of available public domain tools.

scholarly journals Recent Advances in Bioplastics: Application and Biodegradation

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 920 ◽  
Author(s):  
Tanja Narancic ◽  
Federico Cerrone ◽  
Niall Beagan ◽  
Kevin E. O’Connor
Keyword(s):  
Biodegradable Polymers ◽  
Biomedical Applications ◽  
Drug Delivery Systems ◽  
State Of The Art ◽  
Weight Ratio ◽  
Challenges And Opportunities ◽  
Single Use ◽  
Art Research ◽  
Degradation Properties ◽  
Design And Application

The success of oil-based plastics and the continued growth of production and utilisation can be attributed to their cost, durability, strength to weight ratio, and eight contributions to the ease of everyday life. However, their mainly single use, durability and recalcitrant nature have led to a substantial increase of plastics as a fraction of municipal solid waste. The need to substitute single use products that are not easy to collect has inspired a lot of research towards finding sustainable replacements for oil-based plastics. In addition, specific physicochemical, biological, and degradation properties of biodegradable polymers have made them attractive materials for biomedical applications. This review summarises the advances in drug delivery systems, specifically design of nanoparticles based on the biodegradable polymers. We also discuss the research performed in the area of biophotonics and challenges and opportunities brought by the design and application of biodegradable polymers in tissue engineering. We then discuss state-of-the-art research in the design and application of biodegradable polymers in packaging and emphasise the advances in smart packaging development. Finally, we provide an overview of the biodegradation of these polymers and composites in managed and unmanaged environments.

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