TERRAIN ROUGHNESS ASSESSMENT FOR HIGH SPEED UGV NAVIGATION IN UNKNOWN HETEROGENEOUS TERRAINS

2010 ◽  
Vol 07 (02) ◽  
pp. 165-176 ◽  
Author(s):  
AHMED EL-KABBANY ◽  
A. RAMIREZ-SERRANO
Keyword(s):  
High Speed ◽  
Life Time ◽  
Closed Form Expression ◽  
Maintenance Cost ◽  
Maximum Speed ◽  
Navigation Systems ◽  
Vehicle Speed ◽  
Range Image ◽  
Transmitted Force ◽  
Terrain Roughness

This paper addresses the problem of determining the maximum allowable speed (V) of a vehicle traversing unknown off-road terrains. The calculated maximum speed achieves the fastest navigation without exceeding an allowable range of transmitted force (Fall) to the vehicle's frame. The proposed system enables the vehicle to transit between different terrains safely. The system's input are: (i) a 3D range image of the terrain and (ii) the vehicle's dimensions and characteristics (e.g., suspension parameters). First the terrain roughness is assessed; then the corresponding maximum allowable speed is calculated. In this paper a novel Roughness Index (RI) is used to represent the terrain roughness. This index is calculated based on the standard deviation of the terrain points' elevations (3D range image). A closed form expression of the maximum allowable vehicle speed is developed (as function of the vehicle's properties, Fall, RI, and probability of not exceeding Fall). The proposed system can be used as a driver assistant system to enhance the vehicle performance, increase its life time, and reduce the maintenance cost. In addition, it is a key module in Unmanned Ground Vehicles (UGVs) navigation systems; as it provides the navigation system with necessary information for path and speed planning.

scholarly journals Numerical Study of Longitudinal Inter-Distance and Operational Characteristics for High-Speed Capsular Train Systems

Vehicles ◽  
2022 ◽  
Vol 4 (1) ◽  
pp. 30-41
Author(s):  
Bruce W. Jo
Keyword(s):  
Error Rate ◽  
High Speed ◽  
Position Control ◽  
Numerical Study ◽  
Design Parameters ◽  
Maximum Speed ◽  
Integer Number ◽  
Vehicle Speed ◽  
Start Time ◽  
Distance Control

High-speed capsular vehicles are firstly suggested as an idea by Elon Musk of Tesla Company. Unlike conventional high-speed trains, capsular vehicles are individual vessels carrying passengers and freight with the expected maximum speed of near 1200 [km/h] in a near-vacuum tunnel. More individual vehicle speed, dispatch, and position control in the operational aspect are expected over connected trains. This numerical study and investigation evaluate and analyze inter-distance control and their characteristics for high-speed capsular vehicles and their operational aspects. Among many aspects of operation, the inter-distance of multiple vehicles is critical toward passenger/freight flow rate and infrastructural investment. In this paper, the system’s equation, equation of the motion, and various characteristics of the system are introduced, and in particular control design parameters for inter-distance control and actuation are numerically shown. As a conclusion, (1) Inter-distance between vehicles is a function of error rate and second car start time, the magnitude range is determined by second car start time, (2) Inter-distance fluctuation rate is a function of error rate and second car start time, however; it can be minimized by choosing the correct second car start time, and (3) If the second car start time is chosen an integer number of push-down cycle time at specific velocity error rate, the inter-distance fluctuation can be zero.

scholarly journals ANALYSIS OF SPEED AND SOCIAL-PSYCHOLOGY FACTORS OF SPEEDING BEHAVIOUR ON DRIVERS IN DKI JAKARTA

2019 ◽  
Vol 2 (3) ◽  
pp. 133
Author(s):  
Andyka Kusuma ◽  
Dewi Maulina ◽  
Almatrisa Mustika Hutami
Keyword(s):  
Social Psychology ◽  
Reaction Time ◽  
High Speed ◽  
Maximum Speed ◽  
Speed Limit ◽  
Vehicle Speed ◽  
Common Cause

Increased vehicle speed will affect the increase in reaction time and distance to stop and the increased possibility of errors that can be done by the driver. The most common cause of accidents faced by many countries is a high speed and exceeding permitted limits because they contribute to the problem of the number and number of fatalities of accident victims. Setting the maximum speed limit can reduce the risk of accidents. The higher the speed, the greater the stop distance needed, and the risk of accidents increases. Kecepatan kendaraan yang meningkat akan berpengaruh terhadap peningkatan waktu reaksi dan jarak untuk berhenti serta meningkatnya kemungkinan kesalahan yang dapat dilakukan oleh pengemudi. Faktor penyebab kecelakaan yang paling sering dihadapi oleh banyak negara adalah kecepatan tinggi dan melebihi batas yang diijinkan karena ikut berkontribusi pada permasalahan jumlah dan kefatalan korban kecelakaan. Mengatur batas kecepatan maksimum dapat menurunkan resiko kecelakaan. Semakin tinggi kecepatan, maka semakin besar jarak berhenti yang dibutuhkan dan resiko kecelakaan semakin meningkat.

scholarly journals CFD Simulation of a Hyperloop Capsule Inside a Low-Pressure Environment Using an Aerodynamic Compressor as Propulsion and Drag Reduction Method

2021 ◽  
Vol 11 (9) ◽  
pp. 3934
Author(s):  
Federico Lluesma-Rodríguez ◽  
Temoatzin González ◽  
Sergio Hoyas
Keyword(s):  
Shock Waves ◽  
Power Consumption ◽  
High Speed ◽  
Cfd Simulation ◽  
Aerodynamic Drag ◽  
Flow Behavior ◽  
Critical Conditions ◽  
Vehicle Speed ◽  
Blockage Ratio ◽  
The Cost

One of the most restrictive conditions in ground transportation at high speeds is aerodynamic drag. This is even more problematic when running inside a tunnel, where compressible phenomena such as wave propagation, shock waves, or flow blocking can happen. Considering Evacuated-Tube Trains (ETTs) or hyperloops, these effects appear during the whole route, as they always operate in a closed environment. Then, one of the concerns is the size of the tunnel, as it directly affects the cost of the infrastructure. When the tube size decreases with a constant section of the vehicle, the power consumption increases exponentially, as the Kantrowitz limit is surpassed. This can be mitigated when adding a compressor to the vehicle as a means of propulsion. The turbomachinery increases the pressure of part of the air faced by the vehicle, thus delaying the critical conditions on surrounding flow. With tunnels using a blockage ratio of 0.5 or higher, the reported reduction in the power consumption is 70%. Additionally, the induced pressure in front of the capsule became a negligible effect. The analysis of the flow shows that the compressor can remove the shock waves downstream and thus allows operation above the Kantrowitz limit. Actually, for a vehicle speed of 700 km/h, the case without a compressor reaches critical conditions at a blockage ratio of 0.18, which is a tunnel even smaller than those used for High-Speed Rails (0.23). When aerodynamic propulsion is used, sonic Mach numbers are reached above a blockage ratio of 0.5. A direct effect is that cases with turbomachinery can operate in tunnels with blockage ratios even 2.8 times higher than the non-compressor cases, enabling a considerable reduction in the size of the tunnel without affecting the performance. This work, after conducting bibliographic research, presents the geometry, mesh, and setup. Later, results for the flow without compressor are shown. Finally, it is discussed how the addition of the compressor improves the flow behavior and power consumption of the case.

Numerical Simulation of Flowfield around High Speed Trains Passing by each other at the same Speed

2011 ◽  
Vol 97-98 ◽  
pp. 698-701
Author(s):  
Ming Lu Zhang ◽  
Yi Ren Yang ◽  
Li Lu ◽  
Chen Guang Fan
Keyword(s):  
Numerical Simulation ◽  
Wind Tunnel ◽  
Flow Field ◽  
Point Source ◽  
High Speed ◽  
Stokes Equations ◽  
Field Structure ◽  
Vehicle Speed ◽  
Mesh Method ◽  
High Speed Trains

Large eddy simulation (LES) was made to solve the flow around two simplified CRH2 high speed trains passing by each other at the same speed base on the finite volume method and dynamic layering mesh method and three dimensional incompressible Navier-Stokes equations. Wind tunnel experimental method of resting train with relative flowing air and dynamic mesh method of moving train were compared. The results of numerical simulation show that the flow field structure around train is completely different between wind tunnel experiment and factual running. Two opposite moving couple of point source and point sink constitute the whole flow field structure during the high speed trains passing by each other. All of streamlines originate from point source (nose) and finish with the closer point sink (tail). The flow field structure around train is similar with different vehicle speed.

scholarly journals Specific Absolute Velocity Thresholds during Male Basketball Games Using Local Positional System; Differences between Age Categories

2021 ◽  
Vol 11 (10) ◽  
pp. 4390
Author(s):  
Carlos Sosa ◽  
Alberto Lorenzo ◽  
Juan Trapero ◽  
Carlos Ribas ◽  
Enrique Alonso ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Real Time ◽  
Effect Size ◽  
High Speed ◽  
Maximum Speed ◽  
Large Effect Size ◽  
Moderate Effect Size ◽  
Positional System ◽  
Moderate Effect ◽  
Distance Zone

The aim of this study was (I) to establish absolute specific velocity thresholds during basketball games using local positional system (LPS) and (II) to compare the speed profiles between various levels of competitions. The variables recorded were total distance (TD); meters per minute (m·min); real time (min); maximum speed (Km h−1), distance (m), percentage distance, and percentage duration invested in four speed zones (standing–walking; jogging; running; and high-speed running). Mean and standard deviation (±SD) were calculated, and a separate one-way analysis of variance was undertaken to identify differences between competitions. TD (3188.84 ± 808.37 m) is covered by standing–walking (43.51%), jogging (36.58%), running (14.68%), and sprinting (5.23%) activities. Overall, 75.22% of the time is invested standing–walking, jogging (18.43%), running (4.77%), and sprinting (1.89%). M·min (large effect size), % duration zone 2 (moderate effect size); distance zone 4 (large effect size), and % distance zone 4 (very large effect size) are significantly higher during junior than senior. However, % distance zone 1 (large effect size) and % duration zone 1 (large effect size) were largely higher during senior competition. The findings of this study reveal that most of the distance and play time is spent during walking and standing activities. In addition, the proportion of time spent at elevated intensities is higher during junior than in senior competition.

High-Speed End Milling Using a Feedforward Control Architecture

1996 ◽  
Vol 118 (2) ◽  
pp. 178-187 ◽  
Author(s):  
E. D. Tung ◽  
M. Tomizuka ◽  
Y. Urushisaki
Keyword(s):  
High Speed ◽  
Feedforward Control ◽  
End Milling ◽  
Phase Error ◽  
Cutting Speed ◽  
Frequency Domain Analysis ◽  
Maximum Speed ◽  
Drive Control ◽  
Machining Errors ◽  
Feedforward Controller

Experiments are performed for end milling aluminum at 15,000 RPM spindle speed (1,508 m/min cutting speed) and up to 3 m/min table feedrate using an experimental machine tool control system. A digital feedforward controller for feed drive control incorporates the Zero Phase Error Tracking Controller (ZPETC) and feedforward friction compensation. The controller achieves near-perfect (±3 μm) tracking over a 26 mm trajectory with a maximum speed of 2 m/min. The maximum contouring error for a 26 mm diameter circle at this speed is less than 4 μm. Tracking and contouring experiments are conducted for table feedrates as high as 10 m/min. Frequency domain analysis demonstrates that the feedforward controller achieves a bandwidth of 10 Hz without phase distortion. In a direct comparison of accuracy, the machining errors in specimens produced by the experimental controller were up to 20 times smaller than the errors in specimens machined by an industrial CNC.

The Analysis and Design of the Dynamic Information Service System Network Architecture of the SOA Based on WAVE Technology

2014 ◽  
Vol 1044-1045 ◽  
pp. 1380-1383
Author(s):  
Guang Li Yin
Keyword(s):  
Network Architecture ◽  
High Speed ◽  
Service System ◽  
Road Traffic ◽  
Rapid Development ◽  
Information Service ◽  
Advanced Technology ◽  
Living Standard ◽  
Vehicle Speed ◽  
Analysis And Design

Safety problem is one of the most attention and concern of driving. This paper in the high-speed on the road cars and car, car and road communications, vehicle real-time status, through the network information service system integration on a platform, on the use of related technologies are analyzed, the design of the software system based on SOA architecture.Keywords: network, GPS module, SOA cross platformI. IntorductionWith the development of science and technology and the improvement of people's living standard, Car popularity rate is high, it's hard to believe, families has two or three car. Whether it is the bus or private car is such rapid development, this will bring a lot of problems in road traffic, such as traffic congestion, traffic accident. These problems affect the normal life and travel, it is necessary to carry out management and provide information service for road use advanced technology. Using mobile phone GPS positioning module can obtain the vehicle speed and the basic information, through processing and optimization of information service system, the analysis of data useful, so as to divert traffic, both for the convenience of the user, but also improve the expressway management ability.

Interface Features of the DDR SDRAM Memory Test Diagnostic Device

2021 ◽  
Vol 26 (3-4) ◽  
pp. 282-290
Author(s):  
S.V. Volobuev ◽  
◽  
V.G. Ryabtsev ◽  
Keyword(s):  
Data Transmission ◽  
High Speed ◽  
Maximum Speed ◽  
Diagnostic Device ◽  
Semiconductor Memory ◽  
Storage Devices ◽  
Memory Modules ◽  
Electronic Elements ◽  
Synchronization Scheme ◽  
Test Diagnostics

The I/О synchronization scheme plays an important role in achieving maximum speed and reliability of data transmission during memory operation. This paper presents the interface architecture of the DDR SDRAM test diagnostic device. It was demonstrated that the proposed interface components provide the formation of a bidirectional synchro signal for gating written and read data when performing test diagnostics of chips and DDR SDRAM memory devices. Compared to traditional methods, the proposed interface components were made on integrated electronic elements, which reduced the size and power consumption. It has been established that the use of a multiphase synchronization system to implement the interface eliminated the use of delay lines, the disadvantages of which are large dimensions and the complexity of changing the delay time. The interface components under consideration are intended for use in test diagnostics devices that have a multiprocessor structure, which increases the speed of forming test actions and reference reactions. The performed functional modeling and debugging of strobe signal generators confirmed the feasibility of the designs. The proposed interface of the test diagnostics device allows performing test diagnostics of modern high-speed chips and semiconductor memory modules at the operating frequency, which increases the reliability of the results obtained. Interface components can be used by manufacturers of test diagnostics tools for modern high-speed storage devices.

scholarly journals Modal Kinematic Analysis of a Parallel Kinematic Robot with Low-Stiffness Transmissions

Robotics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 132
Author(s):  
Paolo Righettini ◽  
Roberto Strada ◽  
Filippo Cortinovis
Keyword(s):  
High Speed ◽  
Parallel Robots ◽  
Maximum Speed ◽  
Kinematic Structure ◽  
End Effector ◽  
New Approach ◽  
Working Space ◽  
Modes Of Vibration ◽  
Parallel Kinematic ◽  
Actuated Joints

Several industrial robotic applications that require high speed or high stiffness-to-inertia ratios use parallel kinematic robots. In the cases where the critical point of the application is the speed, the compliance of the main mechanical transmissions placed between the actuators and the parallel kinematic structure can be significantly higher than that of the parallel kinematic structure itself. This paper deals with this kind of system, where the overall performance depends on the maximum speed and on the dynamic behavior. Our research proposes a new approach for the investigation of the modes of vibration of the end-effector placed on the robot structure for a system where the transmission’s compliance is not negligible in relation to the flexibility of the parallel kinematic structure. The approach considers the kinematic and dynamic coupling due to the parallel kinematic structure, the system’s mass distribution and the transmission’s stiffness. In the literature, several papers deal with the dynamic vibration analysis of parallel robots. Some of these also consider the transmissions between the motors and the actuated joints. However, these works mainly deal with the modal analysis of the robot’s mechanical structure or the displacement analysis of the transmission’s effects on the positioning error of the end-effector. The discussion of the proposed approach takes into consideration a linear delta robot. The results show that the system’s natural frequencies and the directions of the end-effector’s modal displacements strongly depend on its position in the working space.

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