scholarly journals The Analysis and Compensation of Elastic Unbalance Torque of the Three-axis Air-bearing Simulator

2021 ◽  
Vol 2095 (1) ◽  
pp. 012083
Author(s):  
Zhanxin Li ◽  
Zizhen Cao ◽  
Wenjie Duan ◽  
Yikang Du ◽  
Haiteng Liu
Keyword(s):  
Mathematical Model ◽  
Structural Design ◽  
Structural Parameters ◽  
Center Of Mass ◽  
Air Bearing ◽  
Floating Platform ◽  
Vertical Stiffness ◽  
Before And After ◽  
Torque Curve ◽  
Initial Attitude

Abstract The most important interfering torque of a three-axis air-bearing simulator is the displacement of the center of mass in the gravity field caused by structural elasticity. In order to characterize the torque, a mathematical model of the interference moment was established. Based on the model, it is suggested that the vertical stiffness and horizontal stiffness of the structure should be equal as far as possible during the structural design, and the elastic unbalance moment can be compensated by the vertical offset of the center of mass of the air floating platform relative to the rotation center after the initial attitude leveling. ABAQUS was used to build a simulation model of the air floating platform, and the changes of the structure’s centroid before and after the gravitational field was applied were extracted by software to simulate the centroid deviation caused by the elastic deformation of the structure, which was used as the characterization to conduct discrete optimization of the structure. The optimal structural parameters were obtained. Then the disturbance torque curve and the corresponding initial centroid offset after initial centroid compensation were calculated by mathematical model. The results are of positive guiding significance to the design of three-axis air-bearing simulator.

The Finite Element Analysis and Structure Optimizing of the 42MN Flatting Mill’s Higher Beam

2010 ◽  
Vol 145 ◽  
pp. 317-320
Author(s):  
Chun Ming Zhang ◽  
Run Yuan Hao
Keyword(s):  
Mathematical Model ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Design ◽  
Structural Parameters ◽  
Element Model ◽  
Optimum Structure ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
The Mathematical Model

This text is on the basis of the investigation of the 42MN flatting mill’s higher beam, establishing the flatting mill’s higher beam’s finite element model and the mathematical model which has optimum structure. According to the results of their structure finite element analysis, weaved the relevant procedures and optimized them, obtained ideal structural parameters, this text provide better ideas and ways for the structural design of the flatting mill’s higher beam.

Structure Optimal Design of Pneumatic 6-DOF Parallel Robot Based on Natural Frequency

2010 ◽  
Vol 450 ◽  
pp. 349-352 ◽  
Author(s):  
Bo Wu ◽  
Li Xu ◽  
Xiao Dong Yu ◽  
Zhi Wei Wang ◽  
He Xu
Keyword(s):  
Mathematical Model ◽  
Optimal Design ◽  
Natural Frequency ◽  
Dynamic Equation ◽  
Structural Design ◽  
Optimization Design ◽  
Structural Parameters ◽  
Parallel Robot ◽  
Optimization Rule ◽  
Design Aspect

. In order to improve the dynamic response rapidity and positioning precision for pneumatic 6-DOF parallel robot from the structural design aspect, a mathematical model of natural frequency for the parallel robot is developed based on dynamic equation by using vibration theory. The influences of structural parameters on minimal natural frequency are analyzed by simulation and an optimization rule of structural parameters based on minimal natural frequency is proposed. The optimization rule has advantages of simplification and efficiency, which provides a new theoretical gist for optimization of structural parameters as well as for checking the results of the actual natural frequency for pneumatic 6-DOF parallel robot. And this new rule is also valuable for structural optimization design of other similar parallel robot.

TO THE STABILITY OF TANK VEHICLES IN THE BRAKE MODE

2019 ◽  
pp. 27-32
Author(s):  
Denys Popelysh ◽  
Yurii Seluk ◽  
Sergyi Tomchuk
Keyword(s):  
Mathematical Model ◽  
Control Systems ◽  
Distribution Systems ◽  
Traffic Accidents ◽  
Road Traffic ◽  
Center Of Mass ◽  
Dynamic Processes ◽  
Course Stability ◽  
The Stability ◽  
Tank Vehicles

This article discusses the question of the possibility of improving the roll stability of partially filled tank vehicles while braking. We consider the dangers associated with partially filled tank vehicles. We give examples of the severe consequences of road traffic accidents that have occurred with tank vehicles carrying dangerous goods. We conducted an analysis of the dynamic processes of fluid flow in the tank and their influence on the basic parameters of the stability of vehicle. When transporting a partially filled tank due to the comparability of the mass of the empty tank with the mass of the fluid being transported, the dynamic qualities of the vehicle change so that they differ significantly from the dynamic characteristics of other vehicles. Due to large displacements of the center of mass of cargo in the tank there are additional loads that act vehicle and significantly reduce the course stability and the drivability. We consider the dynamics of liquid sloshing in moving containers, and give examples of building a mechanical model of an oscillating fluid in a tank and a mathematical model of a vehicle with a tank. We also considered the method of improving the vehicle’s stability, which is based on the prediction of the moment of action and the nature of the dynamic processes of liquid cargo and the implementation of preventive actions by executive mechanisms. Modern automated control systems (anti-lock brake system, anti-slip control systems, stabilization systems, braking forces distribution systems, floor level systems, etc.) use a certain list of elements for collecting necessary parameters and actuators for their work. This gives the ability to influence the course stability properties without interfering with the design of the vehicle only by making changes to the software of these systems. Keywords: tank vehicle, roll stability, mathematical model, vehicle control systems.

scholarly journals Transfer and generalization of learned manipulation between unimanual and bimanual tasks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Trevor Lee-Miller ◽  
Marco Santello ◽  
Andrew M. Gordon
Keyword(s):  
Learning Transfer ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Pressure Point ◽  
Torque Generation ◽  
Before And After ◽  
Object Center ◽  
High Level ◽  
Bimanual Grasping ◽  
Partial Learning

AbstractSuccessful object manipulation, such as preventing object roll, relies on the modulation of forces and centers of pressure (point of application of digits on each grasp surface) prior to lift onset to generate a compensatory torque. Whether or not generalization of learned manipulation can occur after adding or removing effectors is not known. We examined this by recruiting participants to perform lifts in unimanual and bimanual grasps and analyzed results before and after transfer. Our results show partial generalization of learned manipulation occurred when switching from a (1) unimanual to bimanual grasp regardless of object center of mass, and (2) bimanual to unimanual grasp when the center of mass was on the thumb side. Partial generalization was driven by the modulation of effectors’ center of pressure, in the appropriate direction but of insufficient magnitude, while load forces did not contribute to torque generation after transfer. In addition, we show that the combination of effector forces and centers of pressure in the generation of compensatory torque differ between unimanual and bimanual grasping. These findings highlight that (1) high-level representations of learned manipulation enable only partial learning transfer when adding or removing effectors, and (2) such partial generalization is mainly driven by modulation of effectors’ center of pressure.

scholarly journals Vision-Based Structural FE Model Updating Using Genetic Algorithm

2021 ◽  
Vol 11 (4) ◽  
pp. 1622
Author(s):  
Gun Park ◽  
Ki-Nam Hong ◽  
Hyungchul Yoon
Keyword(s):  
Genetic Algorithm ◽  
Model Updating ◽  
Structural Parameters ◽  
Fe Model ◽  
Structural Members ◽  
Stiffness Reduction ◽  
Before And After ◽  
Scale Test ◽  
Fe Model Updating ◽  
Story Building

Structural members can be damaged from earthquakes or deterioration. The finite element (FE) model of a structure should be updated to reflect the damage conditions. If the stiffness reduction is ignored, the analysis results will be unreliable. Conventional FE model updating techniques measure the structure response with accelerometers to update the FE model. However, accelerometers can measure the response only where the sensor is installed. This paper introduces a new computer-vision based method for structural FE model updating using genetic algorithm. The system measures the displacement of the structure using seven different object tracking algorithms, and optimizes the structural parameters using genetic algorithm. To validate the performance, a lab-scale test with a three-story building was conducted. The displacement of each story of the building was measured before and after reducing the stiffness of one column. Genetic algorithm automatically optimized the non-damaged state of the FE model to the damaged state. The proposed method successfully updated the FE model to the damaged state. The proposed method is expected to reduce the time and cost of FE model updating.

Detection of Vehicle Tripped and Untripped Rollovers by a Novel Index With Mass-Center-Position Estimations

2017 ◽  
Author(s):  
Fengchen Wang ◽  
Yan Chen
Keyword(s):  
Load Transfer ◽  
Center Of Mass ◽  
Roll Motion ◽  
Mass Center ◽  
Motion Models ◽  
Center Position ◽  
Before And After ◽  
Vehicle Rollover ◽  
Lift Off ◽  
Rollover Index

This paper presents a novel mass-center-position (MCP) metric for vehicle rollover propensity detection. MCP is first determined by estimating the positions of the center of mass of one sprung mass and two unsprung masses with two switchable roll motion models, before and after tire lift-off. The roll motion information without saturation can then be provided through MCP continuously. Moreover, to detect completed rollover statues for both tripped and untripped rollovers, the criteria are derived from d’Alembert principle and moment balance conditions based on MCP. In addition to tire lift-off, three new rollover statues, rollover threshold, rollover occurrence, and vehicle jumping into air can be all identified by the proposed criteria. Compared with an existing rollover index, lateral load transfer ratio, the fishhook maneuver simulation results in CarSim® for an E-class SUV show that MCP metric can successfully predict the vehicle impending rollover without saturation for untripped rollovers. Tripped rollovers caused by a triangle road bump are also successfully detected in the simulation. Thus, MCP metric can be successfully applied for rollover propensity prediction.

Motion Simulation of Key Components in a Package Machine

2012 ◽  
Vol 557-559 ◽  
pp. 2303-2306
Author(s):  
Shu Bin Kan
Keyword(s):  
Structural Parameters ◽  
Center Of Mass ◽  
Motion Simulation ◽  
Software Environment ◽  
Optimization Result ◽  
Adams Software ◽  
Motion Characteristic ◽  
The Moment ◽  
Selection Of

The motion characteristic of key components is a decisional factor to the working reliability and stability of a package machine. In this paper, the motion simulation of a key component is carried out in the ADAMS software environment. By analysis of the force, variance of the center-of-mass and the moment of the component, the mutation point in the motion is found, and then the structure is optimized by selection of different structural parameters. The optimization result shows a significant improvement for the reliability and stability of the whole machine.

The Dynamic Characteristics of Rigid Frame Single-Rib Arch Bridge

2013 ◽  
Vol 368-370 ◽  
pp. 1426-1430
Author(s):  
Li Xiong Gu ◽  
Rong Hui Wang
Keyword(s):  
Dynamic Characteristics ◽  
Bending Strength ◽  
Dynamic Properties ◽  
Structural Parameters ◽  
Bending Stiffness ◽  
Torsional Stiffness ◽  
Lateral Stiffness ◽  
Arch Bridge ◽  
Vertical Stiffness ◽  
Rigid Frame

In this paper, by establishing the finite element model to study the dynamic characteristics of rigid frame single-rib arch bridge. By respectively changing structural parameters of the span ratios, and the compressive stiffness of arch, and the bending stiffness of arch, and the bending stiffness of bridge girder, and the layout of boom to find out the regularity of the structure on lateral stiffness, and vertical stiffness, and torsional stiffness as well as dynamic properties, it come out the results of that lateral stiffness of the structure is weaker, and increasing the span ratios and the compressive strength of arch are conducive to the improvement of the overall stiffness, and improving the bending strength of arch and layout of boom are less effect on the overall stiffness and mode shape.

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