Modeling the Dynamics of Five-Axis Machine Tool Using the Multibody Approach

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Hoai Nam Huynh ◽  
Yusuf Altintas
Keyword(s):  
Rigid Body ◽  
Machine Tool ◽  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Dynamic Performance ◽  
Body Motion ◽  
Proposed Model ◽  
Multibody Dynamic ◽  
Machining Operations ◽  
Five Axis

Abstract A systematic modeling of multibody dynamics of five-axis machine tools is presented in this article. The machine is divided into major subassemblies such as spindle, column, bed, tool changer, and longitudinal and rotary drives. The inertias and mass center of each subassembly are calculated from the design model. The subassemblies are connected with elastic springs and damping elements at contact joints to form the complete multibody dynamic model of the machine that considers the rigid body kinematics and structural vibrations of the machine at any point. The unknown elastic joint parameters are estimated from the experimental modal analysis of the machine tool. The resulting position-dependent multibody dynamic model has the minimal number of degrees-of-freedom that is equivalent to the number of measured modes, as opposed to thousands used in finite element models. The frequency response functions of the machine can be predicted at any posture of the five-axis machine, which are compared against the directly measured values to assess the validity of model. The proposed model can predict the combined rigid body motion and vibrations of the machine with computational efficiency, and hence, it can be used as a digital twin to simulate its dynamic performance in machining operations and tracking control tests of the servo drives.

scholarly journals Modeling Legged Microrobot Locomotion Based on Contact Dynamics and Vibration in Multiple Modes and Axes

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Jinhong Qu ◽  
Clark B. Teeple ◽  
Kenn R. Oldham
Keyword(s):  
Rigid Body ◽  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Beam Theory ◽  
Contact Dynamics ◽  
Body Motion ◽  
Small Scale ◽  
Robot Locomotion ◽  
Actuation Scheme ◽  
Dynamics And Vibration

A dynamic model is developed for small-scale robots with multiple high-frequency actuated compliant elastic legs and a rigid body. The motion of the small-scale robots results from dual-direction motion of piezoelectric actuators attached to the legs, with impact dynamics increasing robot locomotion complexity. A dynamic model is developed to describe the small-scale robot motion in the presence of variable properties of the underlying terrain. The dynamic model is derived from beam theory with appropriate boundary and loading conditions and considers each robot leg as a continuous structure moving in two directions. Robot body motion is modeled in up to five degrees-of-freedom (DOF) using a rigid body approximation for the central robot chassis. Individual modes of the resulting multimode robot are treated as second-order linear systems. The dynamic model is tested with two different centimeter-scale robot prototypes having an analogous actuation scheme to millimeter-scale microrobots. In accounting for the interaction between the robot and ground, a dynamic model using the first two modes of each leg shows good agreement with experimental results for the centimeter-scale prototypes, in terms of both magnitude and the trends in robot locomotion with respect to actuation conditions.

Dynamic Model of the Piston-Ring Assembly Using Curved Beam Finite Elements

2011 ◽  
Author(s):  
Mohannad Hakeem ◽  
Nabil G. Chalhoub ◽  
Peter Schihl
Keyword(s):  
Rigid Body ◽  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Piston Ring ◽  
Translational Motion ◽  
Total Duration ◽  
Variable Structure ◽  
Body Motion ◽  
Curved Beam ◽  
Connecting Rod

A dynamic model for the crankshaft/connecting-rod/piston-assembly for a single cylinder engine is developed. The model considers the rigid body motion of the crank-slider mechanism including the piston secondary motions such as the piston-slap and piston-tilting. The formulation considers the ring to have three rigid body degrees of freedom in addition to its longitudinal and in-plane transverse deformations. The structural flexibility terms are approximated by using curved beam finite element method. The dynamic model has a variable structure whereby the number of degrees of freedom depends on the piston-liner and piston-ring interactions. Its formulation does not include frictional losses. The simulation results illustrate the piston secondary motions along with the ring tilting angles relative to the piston orientation for the total duration of the engine cycle. In addition, they exhibit the translational motion of the ring within the piston groove.

Structural Control of an Ultra-Large Semi-Submersible Floating Offshore Wind Turbine

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Zhixin Zhao ◽  
Wenhua Wang ◽  
Dongdong Han ◽  
Wei Shi ◽  
Yulin Si ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Dynamic Model ◽  
Structural Control ◽  
Degrees Of Freedom ◽  
Vibration Suppression ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Floating Platform ◽  
Floating Offshore Wind Turbine ◽  
Proposed Model

Abstract A braceless semi-submersible floating platform is proposed for a Technical University of Denmark (DTU) 10-MW wind turbine at moderate water depths with reference to an existing National Renewable Energy Laboratory (NREL) 5-MW braceless semi-submersible floating platform, and a servo control system for a 10-MW semi-submersible floating offshore wind turbine (FOWT) is introduced. To control the ultimate and fatigue loads of the FOWT, a fore-aft tuned mass damper (TMD) installed in the nacelle of the 10-MW semi-submersible FOWT was investigated for vibration alleviation and load reduction. Considering the hydrodynamic and mooring effect, a four degrees-of-freedom (DOFs) (platform surge and pitch motions, tower fore-aft bending, and TMD translation) simplified dynamic model for the 10-MW semi-submersible FOWT is established based on D’Alembert’s principle. Then, the parameter estimation is conducted based on the Levenberg–Marquardt (LM) algorithm, and the simplified dynamic model was further verified by comparing the output responses with FAST and the proposed model. Furthermore, the exhaustive search (ES) and genetic algorithm (GA) are embedded into the simplified dynamic model to optimize the TMD parameters. Finally, a fully coupled time-domain simulation for all the selected environmental conditions is conducted in FAST, and the vibration suppression performance of the optimized TMD design for the 10-W semi-submersible FOWT was further examined and analyzed.

Coordinated Motion Planning of Legged Mobile Manipulator for Tracking the Given End-Effector’s Trajectory

2019 ◽  
Author(s):  
Kondalarao Bhavanibhatla ◽  
Sulthan Suresh-Fazeela ◽  
Dilip Kumar Pratihar
Keyword(s):  
Motion Planning ◽  
Degrees Of Freedom ◽  
Robotic System ◽  
Simulation Software ◽  
Body Motion ◽  
Whole Body ◽  
Mobile Manipulator ◽  
Coordinated Motion ◽  
Multibody Dynamic ◽  
The Given

Abstract In this paper, a novel algorithm is presented to achieve the coordinated motion planning of a Legged Mobile Manipulator (LMM) for tracking the given end-effector’s trajectory. LMM robotic system can be obtained by mounting a manipulator on the top of a multi-legged platform for achieving the capabilities of both manipulation and mobility. To exploit the advantages of these capabilities, the manipulator should be able to accomplish the task, while the hexapod platform moves simultaneously. In the presented approach, the whole-body motion planning is achieved in two steps. In the first step, the robotic system is assumed to be a mobile manipulator, in which the manipulator has two additional translational degrees of freedom at the base. The redundancy of this robotic system is solved by treating it as an optimization problem. Then, in the second step, the omnidirectional motion of the legged platform is achieved with a combination of straight forward and crab motions. The proposed algorithm is tested through a numerical simulation in MATLAB and then, validated on a virtual model of the robot using multibody dynamic simulation software, MSC ADAMS. Multiple trajectories of the end-effector have been tested and the results show that the proposed algorithm accomplishes the given task successfully by providing a singularity-free whole-body motion.

Tool Path Planning and NC Generation of Tilted Plane Machining Features for Five-Axis Machining

2011 ◽  
Vol 697-698 ◽  
pp. 309-313 ◽  
Author(s):  
Chen Hua She ◽  
Yueh Hsun Tsai
Keyword(s):  
Machine Tool ◽  
Degrees Of Freedom ◽  
Tool Path ◽  
Simulation Software ◽  
Free Form ◽  
Parent Child Relationship ◽  
Machining Feature ◽  
Machining Errors ◽  
Tilted Plane ◽  
Five Axis

Designs of free-form surface products are becoming increasingly complex. In traditional three-axis machine tool machining, errors that are caused by repetitive positioning and the costs of fixture jig design and manufacturing are critical. Since multi-axis machining provides two more rotational degrees of freedom than a three-axis machine tool, the former can solve these problems, and has therefore become the trend of precision cutting. As multi-axis machined parts often have holes and grooves on the tilted plane, this work proposes a method for machining tilted working plane features and for NC generation on a five-axis machine. The developed module can provide common geometric features, allowing the user to alter the machining feature and sequence on the tilted plane quickly using the parent-child relationship in a tree diagram, and plan the tool path. The postprocessor module developed in this paper can transform the tool path into an NC program required for machining. Finally, solid cutting simulation software is utilized to confirm the feasibility and correctness of the tool path and NC data of the tilted plane machining feature.

Nonlinear Model Based Estimation of Rigid-Body Motion Via an Indirect Measurement of an Elastic Appendage

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
M. Senesh ◽  
A. Wolf ◽  
O. Gottlieb
Keyword(s):  
Nonlinear System ◽  
Rigid Body ◽  
Nonlinear Model ◽  
Estimation Procedure ◽  
Indirect Measurement ◽  
Body Motion ◽  
System Parameters ◽  
Model Based ◽  
Proposed Model ◽  
Linear And Nonlinear

In this paper, we develop and implement a nonlinear model based procedure for the estimation of rigid-body motion via an indirect measurement of an elastic appendage. We demonstrate the procedure by motion analysis of a compound planar pendulum from indirect optoelectronic measurements of markers attached to an elastic appendage that is constrained to slide along the rigid-body axis. We implement a Lagrangian approach to derive a theoretical nonlinear model that consistently incorporates several generalized forces acting on the system. Identification of the governing linear and nonlinear system parameters is obtained by analysis of frequency and damping backbone curves from controlled experiments of the decoupled system elements. The accuracy of the proposed model based procedures is evaluated and its results are compared with those of a previously reported point cluster estimation procedure. Two cases are investigated to yield 1.7% and 3.4% errors between measured motion and its model based estimation for experimental configurations, with a slider mass to pendulum frequency ratios of 12.8 and 2.5, respectively. Motion analysis of system dynamics with the point cluster method reveals a noisy signal with a maximal error of 3.9%. Thus, the proposed model based estimation procedure enables accurate evaluation of linear and nonlinear system parameters that are not directly measured.

Control of Flexible Payloads Grasped by Actuated Grippers Undergoing Large Rigid-Body Motions: Part II — Controllability and Observability

2002 ◽  
Author(s):  
Edward J. Park ◽  
James K. Mills
Keyword(s):  
Rigid Body ◽  
Dynamic Model ◽  
Time Scale ◽  
Body Motion ◽  
Deformation Control ◽  
Scale Modeling ◽  
Fixed Interface ◽  
Controllability And Observability ◽  
Scale Behavior ◽  
Selection Of

Part I of this work models the dynamics of a flexible payload grasped by an actuated gripper undergoing large rigid body motion by a robotic manipulator. In Part II, the controllability and observability conditions of the system are discussed. In Part I, the dynamic model of the actuated flexible payload is derived using the component mode synthesis (CMS) method with addition of actuator constraint, fixed-interface vibration and quasi-static modes. Here, the two-time scale modeling (TSM) technique is employed taking advantage of the two-time scale behavior between the quasi-static modes and vibration modes in the dynamic model. Due to the complexity of the resulting system, the controllability and observability conditions are not trivial. Hence, the controllability and observability study addressed herein becomes essential in showing the advantages of using the CMS and TSM techniques in control system design for the problem. A simulation example demonstrates that simultaneous vibration and quasi-static deformation control is achievable by proper selection of each type of modes.

RTCP Detection for Five-Axis CNC Machine Tool Dynamic Performance Based on 8-shape Trajectory

2019 ◽  
Author(s):  
Qicheng Ding ◽  
Wei Wang ◽  
Zhong Jiang ◽  
Jing Zhang ◽  
Li Du ◽  
...  
Keyword(s):  
Machine Tool ◽  
Dynamic Performance ◽  
Cnc Machine Tool ◽  
Cnc Machine ◽  
Five Axis

Accuracy evaluation of rotary axes of five-axis machine tools with a single setup of a double ball bar

2016 ◽  
Vol 231 (3) ◽  
pp. 427-436 ◽  
Author(s):  
Xiaogeng Jiang ◽  
Robert J Cripps
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Dynamic Performance ◽  
Second Step ◽  
Accuracy Evaluation ◽  
Rotary Axes ◽  
Double Ball Bar ◽  
Ball Bar ◽  
Five Axis ◽  
Rotary Type

A double ball bar (DBB) is used extensively to evaluate the geometric and dynamic performance of three-axis machine tools by means of the XY, YZ and XZ planar circular tests. However, research using a DBB to test the rotary axes of five-axis machine tools simply, quickly and effectively is scarce. In this paper, a method having two steps to identify the imprecision of the rotary axes caused by the position-independent geometric errors (PIGEs) is presented for a tilting rotary type five-axis machine tool using a DBB. The first step is designed to evaluate two rotary axes with one setup. Its advantage of fast diagnosis effectively reduces the machine down time, and thus can be employed as a quick testing approach of the machine tool. However, if some of the diagnosed errors fall outside their tolerances, a more accurate but slower check needs to be carried out due to the limitation of the first step. The second step aims to test the two rotary axes separately, each in two sub-steps. By means of varying the position of the pivot, the A- and C-axes can be tested individually. Both steps are performed with only one axis moving, thus simplifying the error analysis. Implementation of the proposed methods was carried out on a Hermle C600U five-axis machine tool. To show the validity of the method, the identified PIGEs are compensated for in each step, which suggests that the first step can be used as a fast and preliminary indication of a five-axis machine tool’s performance, whilst the second can be carried out if a more thorough evaluation is needed.

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