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Nelson Woo

In Machinery, Machinery General, Research

Auto-positioning of sliding planes based on virtual force

Auto-positioning of sliding planes based on virtual force

Eun Ho Kim, Kyung Woon Kwak, Young Kook Kim, Soohyun Kim, Byung Man Kwak, In Gwun Jang, Kyung Soo Kim, International Journal of Control, Automation and Systems, August 2013, Volume 11, Issue 4, pp 798-804.

Abstract

In this paper, an auto-positioning algorithm for sliding planes is newly proposed in two different forms: the General Virtual Force Algorithm (GVFA) and the Applied Virtual Force Algorithm (AVFA). The proposed algorithm is then applied to an auto-positioning spreader which can slide on the top surface of a container with 3 degrees of freedom (DOF). This enables the spreader to handle containers even on a wavy open sea, where the inevitable swinging motion of a spreader leads to significant misalignment from the container during landing. With numerical simulation and experiments using a 1/20 scale model, it is verified that the proposed algorithms provide a robust and reliable solution for in-plane path-finding. Considering the limited space and cost for sensor equipment, however, using AVFA with 8 sensors can be a better solution for an actual application regardless of the slight sacrifice in performance in terms of operation time and energy consumed.

How Multibody Dynamics Simulation Technology is Used

A newly proposed auto-positioning algorithm for sliding planes was tested using RecurDyn and scale testing. Scale testing was able to validate the RecurDyn model. RecurDyn simulations were able to prove that the algorithms provide a robust and reliable solution for path finding.

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In Nonlinear Dynamic System Theory, Research

Dynamics and Control Research of Rotary Table Based on Virtual Prototype

Dynamics and Control Research of Rotary Table Based on Virtual Prototype

Zifan Fang, Dexin Wu, Huapan Xiao, Hui Li, Kongde He, Weihua Yang, Intelligent Human-Machine Systems and Cybernetics (IHMSC) 5th International Conference, Hangzhou, August 2013, Volume 2, pp. 457-462.

In Machinery, Machinery General, Research

Dynamic Analysis of Needle Roller Bearings on Torque Loss

Dynamic Analysis of Needle Roller Bearings on Torque Loss

Atsushi Suzuki, Hideki Sugiura, Miki Mizono, Mizuho Inagaki, Tsune Kobayashi, Journal of System Design and Dynamics, 2013, Volume 7, No. 4, pp 405-415.

Abstract

Automatic transmissions consist of several planetary gear sets that are utilized to change gears. Needle roller bearings are widely employed in planetary gears used under high-load and high-speed conditions, and thus the torque loss of these bearings is an important issue in designing high-efficiency transmissions. In this paper, a dynamic analysis is conducted using a multibody dynamics model to investigate friction losses in the needle roller bearings that support pinions. This numerical model takes into consideration the detailed conditions of contact and friction between the needle rollers and other parts. A discrete sphere model is used in the contact analysis to simulate the load distribution for the needle rollers. The friction coefficient is defined as a function of sliding velocity, and is used to describe the experimentally determined relationship between the skew angle and thrust force of needle rollers. The measurements obtained for the axial force of a pinion validate the predictions of the numerical model. A numerical analysis is conducted to evaluate the radial and cage pocket clearances of needle roller bearings, and it is found that the cage pocket clearance is a dominant factor affecting the friction loss of pinion. An increase in loss is caused by the thrust force generated by the skew of the needle rollers. Consequently, the cage pocket clearance needs to be small so as to lessen the friction loss of the bearing.

How Multibody Dynamics Simulation Technology is Used

RecurDyn is used to analyze the design of needle roller bearings in the planetary gears of an automatic transmission. Dynamic analysis in RecurDyn yielded the mechanisms of skew motion, the thrust force of the needle rollers, the axial force of the pinion and the friction torque. As a result, the design could be changed to reduce torque loss in the needle roller bearings.

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April 8, 2013: FunctionBay Joins the MathWorks Connections Program

FOR IMMEDIATE RELEASE

FunctionBay Joins the MathWorks Connections Program

RecurDyn/Control and Simulink Used Together to Cosimulate High-Fidelity Mechanical Models Controlled by Complex Control Systems

April 8, 2013, Pangyo Seven Venture Valley, South Korea – FunctionBay, due to its MATLAB control systems interface RecurDyn/Control, has gained membership to the MathWorks Connections Program. Joining the MathWorks Connections Program certifies RecurDyn as a complimentary product to MATLAB and Simulink, and ensures closer collaboration between FunctionBay and MathWorks in order to deliver greater benefit to end users.

Analysts use RecurDyn/Control and Simulink to cosimulate high-fidelity mechanical models being controlled by complex control systems. This eliminates the need to oversimplify mechanical plant models in the control system model, allowing for more accurate results when evaluating the performance of the combined system. The technology is typically applied to vehicles, robots, and machinery, among other applications.

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In Machinery, Machinery with Belts/Chains/Cables, Research

Modelling of Gear Meshing: A Numerical Approach for Dynamic Behavior Estimation of Thin Gears

Modelling of Gear Meshing: A Numerical Approach for Dynamic Behavior Estimation of Thin Gears

Francesca Cura, Carlo Rosso, Topics in Nonlinear Dynamics, April 2013, Volume 35, Conference Proceedings of the Society for Experimental Mechanics Series, pp. 319-333.

Abstract

The paper deals with the numerical analysis of thin gears. In particular, a brief overview of literature modeling techniques is reported in order to understand the best way for analyzing the dynamic behavior of gears. Then a multibody commercial software is used for implementing different complexity levels of models. The study starts with a simplified model that considers rigid the gears and concentrates the stiffness in the contact between teeth. The second, and more complex, model considers the stiffness in the contact and adds the compliance of the teeth. Stiffness of tooth is depicted as a rotational stiffness placed at the tooth root. Then, the third model increases the complexity, in fact the second model is complicated introducing the compliance of the gear body. In order to do that, a modal analysis of the gears is conducted and the synthetized modal shapes of the gears are introduced in the multibody model. The comparison highlights how the dynamic behavior of thin gears is really important in the meshing force estimation, in fact the transmission error becomes more irregular and the contact forces increase. As a second aspect, this analysis emphasizes the influence of the contact damping and the contact friction in the backlash phenomenon.

How Multibody Dynamics Simulation Technology is Used

The transmission dynamics of very thin gears is studied using a fully rigid model, RFlex and FFlex. It is concluded that the compliance of the gear bodies could deeply affect the transmission behavior. These dynamics could easily be missed if the gears were assumed to be rigid bodies.

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