scholarly journals Dynamic Rocker-Bogie: Kinematical Analysis in a High-Speed Traversal Stability Enhancement

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Sunxin Wang ◽  
Yan Li
Keyword(s):  
High Speed ◽  
Stability Margin ◽  
Suspension System ◽  
Rough Terrain ◽  
Operating Modes ◽  
Uneven Terrain ◽  
Major Shortcoming ◽  
Stability Enhancement ◽  
Travel Rate ◽  
Original Configuration

The rocker-bogie suspension system has robust capabilities to deal with uneven terrain because of its distributing of the payload over its six wheels uniformly, while there is one major shortcoming to high-speed traversal over the planar terrain. This paper proposes a new dynamic rocker-bogie suspension system with two modes of operation: it can expand the span of the rocker-bogie support polygon to increase travel rate when the terrain is planar; and it can switch to its original configuration to move by low speed when it is faced with rough terrain. The analysis on dynamic stability margin and kinematical simulation on the two operating modes of rocker-bogie are employed to analyze and verify the rationality and effectiveness of the modification in the structure.

High-speed hazard avoidance for mobile robots in rough terrain

2004 ◽  
Author(s):  
Matthew J. Spenko ◽  
Karl D. Iagnemma ◽  
Steven Dubowsky
Keyword(s):  
Mobile Robots ◽  
High Speed ◽  
Rough Terrain ◽  
Hazard Avoidance

Research on a high power density mechanical-electrical-hydraulic regenerative suspension system for high-speed tracked vehicles

2021 ◽  
pp. 095440702110610
Author(s):  
Chao Wang ◽  
Weijie Zhang ◽  
Guosheng Wang ◽  
Yong Guo
Keyword(s):  
Power Density ◽  
High Power ◽  
High Speed ◽  
Excitation Amplitude ◽  
Suspension System ◽  
Level Energy ◽  
High Power Density ◽  
Damping Force ◽  
Tracked Vehicles ◽  
Energy Regeneration

High power density energy regeneration is one of the effective solutions to solve the contradiction between improving the damping performance and energy consumption of active suspension. The hydraulic commutator is used to realize hydraulic rectification and hydraulic variable speed/pump/motor with few teeth difference gear pairs is used to match the speed, combined with permanent magnet motor power generation and power supply to put forward kilowatt level high power density mechanical-electrical-hydraulic regenerative suspension system for high-speed tracked vehicles. The mathematical model and fluid-solid-thermo-magnetic multiphysics coupling model are built to analyze the damping performance and regenerative characteristics of the system under passive and semi-active working conditions. The simulation results show that the damping force of the system increases with the increase of the road excitation amplitude and the semi-active control can be realized by adjusting the duty cycle with the PWM control rectifier module. The high power density mechanical-electrical-hydraulic regenerative suspension system can realize kilowatt level energy regeneration, and the regenerative efficiency is more than 50% under low-frequency excitation. The temperature rise of the system is low during operation, which is helpful to improve the reliability and service life.

Stability Enhancement of Supercavitating Projectiles by Unsteady Air Injection

2005 ◽  
Author(s):  
Yasmin Khakpour ◽  
Miad Yazdani
Keyword(s):  
Numerical Simulation ◽  
Drag Reduction ◽  
High Speed ◽  
The Body ◽  
Air Injection ◽  
Cavity Surface ◽  
The Stability ◽  
Stability Enhancement

In this work, numerical simulation is used to study the stability enhancement of high speed supercavitating hydrofoils. Although supercavitation is known as one of the most effective methods for drag reduction, producing the cavity, either by ventilation or by cavitator at front of the body, may cause some instabilities on cavity surface and thus on the projectile’s motion. Therefore removing these instabilities comes as an important point of discussion. First of all, we calculate the sources of instabilities and measure respective forces and then present some approaches that significantly reduce these instabilities. One of these methods that could produce more stable supercavities is injecting of the air into the cavity unsteadily which varies through the projectile’s surface. This approach is provided by arrays of slots distributed on the projectile’s surface and unsteady injection is modeled over the surface. Furthermore, the position of ventilation, dramatically affects the stability like those in aerodynamics. In all approaches it is assumed that the supercavity covers the whole of the body, however the forces caused by the wakes, formed behind the body are taken into account. The calculation is performed at three cavitation numbers with respective velocities of 40 m/s, 50 m/s, 60 m/s.

A measurement method for the overturning coefficient of high-speed trains passing through complex terrain sections under strong wind conditions

2019 ◽  
Vol 234 (8) ◽  
pp. 885-895
Author(s):  
Zhaijun Lu ◽  
Weijia Huang ◽  
Mu Zhong ◽  
Dongrun Liu ◽  
Tian Li ◽  
...  
Keyword(s):  
Real Time ◽  
Complex Terrain ◽  
High Speed ◽  
Suspension System ◽  
Strong Wind ◽  
Real Time Monitoring ◽  
Monitoring Method ◽  
High Speed Trains ◽  
Strong Winds ◽  
Pass Through

Real-time monitoring of overturning coefficients is very important for ensuring the safety of high-speed trains passing through complex terrain sections under strong wind conditions. In recent years, the phenomenon of “car swaying” that occurs when trains pass through the complex terrain has brought new challenges to ensuring the safety and riding comfort of passengers. In China, more and more high-speed trains are facing strong wind environments when running in complex terrain sections. However, due to the limitation of objective conditions, so far, only a few economical and effective methods of measurement have been developed that are suitable for real-time monitoring of the overturning coefficient of commercial vehicles. Therefore, considering the applicability and universality of such a monitoring method, this study presents a method for measuring the overturning coefficient of trains using the primary suspension system under strong winds. A vehicle test was carried out to verify the accuracy of the method. The results show that after correction, the overturning coefficient obtained from the primary suspension system is generally consistent with the overturning coefficient obtained from the instrumented wheelset. The method of measuring the overturning coefficient of trains in strong wind environments with the primary suspension system is, thus, proven feasible.

scholarly journals Road Profile Estimation Using a 3D Sensor and Intelligent Vehicle

Sensors ◽  
2020 ◽  
Vol 20 (13) ◽  
pp. 3676 ◽  
Author(s):  
Tao Ni ◽  
Wenhang Li ◽  
Dingxuan Zhao ◽  
Zhifei Kong
Keyword(s):  
Real Time ◽  
Autonomous Vehicles ◽  
Active Suspension ◽  
Suspension System ◽  
Global Navigation Satellite Systems ◽  
Cloud Data ◽  
Uneven Terrain ◽  
Road Profile ◽  
Data Points ◽  
Profile Estimation

Autonomous vehicles can achieve accurate localization and real-time road information perception using sensors such as global navigation satellite systems (GNSSs), light detection and ranging (LiDAR), and inertial measurement units (IMUs). With road information, vehicles can navigate autonomously to a given position without traffic accidents. However, most of the research on autonomous vehicles has paid little attention to road profile information, which is a significant reference for vehicles driving on uneven terrain. Most vehicles experience violent vibrations when driving on uneven terrain, which reduce the accuracy and stability of data obtained by LiDAR and IMUs. Vehicles with an active suspension system, on the other hand, can maintain stability on uneven roads, which further guarantees sensor accuracy. In this paper, we propose a novel method for road profile estimation using LiDAR and vehicles with an active suspension system. In the former, 3D laser scanners, IMU, and GPS were used to obtain accurate pose information and real-time cloud data points, which were added to an elevation map. In the latter, the elevation map was further processed by a Kalman filter algorithm to fuse multiple cloud data points at the same cell of the map. The model predictive control (MPC) method is proposed to control the active suspension system to maintain vehicle stability, thus further reducing drifts of LiDAR and IMU data. The proposed method was carried out in outdoor environments, and the experiment results demonstrated its accuracy and effectiveness.

Development of a hybrid ozonation biofilm-membrane filatration process for the production of drinking water

2005 ◽  
Vol 51 (6-7) ◽  
pp. 241-248 ◽  
Author(s):  
T. Leiknes ◽  
M. Lazarova ◽  
H. Ødegaard
Keyword(s):  
Drinking Water ◽  
Organic Matter ◽  
High Speed ◽  
Membrane Surface ◽  
Drinking Water Treatment ◽  
Rotating Disk ◽  
Operating Conditions ◽  
Operating Modes ◽  
High Concentrations ◽  
Biomass Separation

Drinking water sources in Norway are characterized by high concentrations of natural organic matter (NOM), low alkalinity and low turbidity. The removal of NOM is therefore a general requirement in producing potable water. Drinking water treatment plants are commonly designed with coagulation direct filtration or NF spiral wound membrane processes. This study has investigated the feasibility and potential of a hybrid process combining ozonation and biofiltration with a rotating disk membrane for treating drinking water with high NOM concentrations. Ozonation will oxidize the NOM content removing colour and form biodegradable organic compounds, which can be removed in biological filters. A constructed water was used in this study which is representative of ozonated NOM-containing water. A rotating membrane disk bioreactor downstream the ozonation process was used to carry out both the biodegradation as well as biomass separation in the same reactor. Maintenance of biodegradation of the organic matter while controlling biofouling of the membrane and acceptable water production rates was the focus in the study. Three operating modes were investigated. Removal of the biodegradable organics was consistent throughout the study indicating that sufficient biomass was maintained in the reactor for all operating conditions tested. Biofouling control was not achieved through shear-induced cleaning by periodically rotating the membrane disks at high speed. By adding a small amount of sponges in the membrane chamber the biofouling could be controlled by mechanical cleaning of the membrane surface during disk rotation. The overall results indicate that the system can favorably be used in an ozonation/biofiltration process by carrying out both biodegradation as well as biomass separation in the same reactor.

scholarly journals Creation of a mathematical model to identify short circuits in power lines

2019 ◽  
Vol 124 ◽  
pp. 02019
Author(s):  
A.N. Alyunov ◽  
O.S. Vyatkina ◽  
I.G. Akhmetova ◽  
B.E. Umirzakov ◽  
D.A. Tashmukhamedova
Keyword(s):  
Mathematical Model ◽  
High Speed ◽  
Power Lines ◽  
Small Length ◽  
Operating Modes ◽  
Modeling Power ◽  
Instantaneous Values ◽  
Short Circuits

We consider the issues of modeling power lines using a self-adjusting mathematical model which allows analyzing the lines operating modes while tracking instantaneous values of parameters. The obtained model can be used to build high-speed protection against phase-to-phase faults in power lines with a voltage of 10–35 kV, which have a small length.

Control of ATRIAS in three dimensions: Walking as a forced-oscillation problem

2020 ◽  
Vol 39 (7) ◽  
pp. 774-796
Author(s):  
Siavash Rezazadeh ◽  
Jonathan W Hurst
Keyword(s):  
Feedback Linearization ◽  
High Speed ◽  
Forced Oscillation ◽  
Vertical Motion ◽  
Three Dimensions ◽  
Singular Perturbation Theory ◽  
Foot Placement ◽  
Uneven Terrain ◽  
Walking Control ◽  
The Stability

In this article, we present a new controller for stable and robust walking control of ATRIAS, an underactuated bipedal robot designed based on the spring-loaded inverted pendulum (SLIP) model. We propose a forced-oscillation scheme for control of vertical motion, which we prove to be stable and contractive. Moreover, we prove that, through some mild assumptions, the dynamics of the system can be written in a hierarchical form that decouples the stability analyses of the horizontal and vertical directions. We leverage these properties to find a stabilizing class of functions for foot placement. The torso control is also proved to be decoupled using singular perturbation theory and is stabilized through a feedback linearization controller. We also take advantage of the proposed framework’s flexibility and extend it to include a new reflex-based uneven-terrain walking control scheme. We test the controller for various desired walking speeds (0 to 2.5 m/s), for stepping up and down unexpected obstacles (15 cm), and for high-speed walking on a random uneven terrain (up to 10 cm of step-ups and step-downs and up to 1.8 m/s). The results show successful performance of the controller and its stability and robustness against various perturbations.

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