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Multibody Dynamics

In Manufacturing, Multibody Dynamics, Research

Implementation of LabVIEW®-based joint-linear motion blending on a lab-manufactured 6-axis articulated robot (RS2)

Implementation of LabVIEW®-based joint-linear motion blending on a lab-manufactured 6-axis articulated robot (RS2)

Dong Sun Lee, Won Jee Chung, Chang Doo Jung, Jun Ho Jang, International Conference on Mechatronics and Automation (ICMA), August 2012, pp. 2423-2428.

  • Abstract

    For fast and accurate motion of 6-axis articulated robot, more noble motion control strategy is needed. In general, the movement strategy of industrial robots can be divided into two kinds, PTP (Point to Point) and CP (Continuous Path). In recent, industrial robots which should be co-worked with machine tools are increasingly needed for performing various jobs, as well as simple handling or welding. Therefore, in order to cope with high-speed handling of the cooperation of industrial robots with machine tools or other devices, CP should be implemented so as to reduce vibration and noise, as well as decreasing operation time. This paper will realize CP motion (especially joint-linear) blending in 3-dimensional space for a 6-axis articulated (lab-manufactured) robot (called as “RS2”) by using LabVIEW® [6] programming, based on a parametric interpolation. Another small contribution of this paper is the proposal of motion blending simulation technique based on Recurdyn® V7, in order to figure out whether the joint-linear blending motion can generate the stable motion of robot in the sense of velocity magnitude at the end-effector of robot or not. In order to evaluate the performance of joint-linear motion blending, simple PTP (i.e., linear-linear) is also physically implemented on RS2. The implementation results of joint-linear motion blending and PTP are compared in terms of vibration magnitude and travel time by using the vibration testing equipment of Medallion of Zonic®. It can be confirmed verified that the vibration peak of joint-linear motion blending has been reduced to 1/10, compared to that of PTP.

    How Multibody Dynamics Simulation Technology is Used

    RecurDyn was used to determine whether changing the velocity profile of a 6-axis articulated robot would result in stable motion of the end-effector. Efficiency of the robot is improved by implementing a control strategy that limits vibration and noise.

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In Biomechanics, Multibody Dynamics, Research

Simulation of extension, radial and ulnar deviation of the wrist with a rigid body spring model

Simulation of extension, radial and ulnar deviation of the wrist with a rigid body spring model

S. Fischli, R.W. Sellens, M. Beek, Dr. Pichora, Journal of Biomechanics, Kingston, June 2009, Volume 42, Issue 9, pp 1363-1366.

Abstract

A novel computational model of the wrist that predicts carpal bone motion was developed in order to investigate the complex kinematics of the human wrist. This rigid body spring model (RBSM) of the wrist was built using surface models of the eight carpal bones, the bases of the five metacarpal bones, and the distal parts of the ulna and radius, all obtained from computed tomography (CT) scans of a cadaver upper limb. Elastic contact conditions between the rigid bodies modeled he influence of the cartilage layers, and ligamentous structures were constructed using nonlinear, tension-only spring elements. Motion of the wrist was simulated by applying forces to the tendons of the five main wrist muscles modeled. Three wrist motions were simulated: extension, ulnar deviation and radial deviation. The model was tested and tuned by comparing the simulated displacement and orientation of the carpal bones with previously obtained CT-scans of the same cadaver arm in deviated (451 ulnar and 151 radial), and extended (571) wrist positions. Simulation results for the scaphoid, lunate, capitate, hamate and tri quetrum are presented here and provide credible prediction of carpal bone movement. These are the first reported results of such a model. They indicate promise that this model will assist in future wrist kinematics investigations. However, further optimization and validation are required to define and guarantee the validity of results.

How Multibody Dynamics Simulation Technology is Used

The high performance and robust contact modeling capabilities in RecurDyn are needed to simulate the complex interactions of bones in the wrist during the transition to various postures.

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In Manufacturing, Multibody Dynamics, Research

A New Method for Simulation of Machining Performance by Integrating Finite Element and Multi-body Simulation for Machine Tools

A New Method for Simulation of Machining Performance by Integrating Finite Element and Multi-body Simulation for Machine Tools

M. Zaeh, D. Siedl, 2007, CIRP Annals – Manufacturing Technology, 2007, Volume 56, Issue 1, pp 383–386.

Abstract

Machine tools need to work accurately and highly dynamically to keep up with the requirements of modern machining processes. Besides the technical issues, time to market is too short to build a real prototype in future. This leads to the necessity for a method which enables the forecast of the future machine performance. To predict the machining results exactly, large movements on flexible structures have to be calculated. With the specific integration of FEA and MBS for the domain of machine tools it is possible to predict the dynamic machine behaviour. The simulation system is based on the relative nodal method for large deformation problems. A model of a machine tool with all relevant components was simulated and matched with experiments to demonstrate the approach.

How Multibody Dynamics Simulation Technology is Used

This paper presents a method to predict machining performance. RecurDyn simulations can provide accurate results for flexible structures with large deformations. Implementing RecurDyn simulations into the design process can reduce time to market and reduce the money spent on physical prototypes.

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