Hybrid-model-based stiffness analysis of a three-revolute-prismatic-spherical parallel kinematic machine

2016 ◽  
Vol 231 (14) ◽  
pp. 2561-2576 ◽  
Author(s):  
Jun Zhang ◽  
Yan Q Zhao ◽  
Hai W Luo
Keyword(s):  
High Speed ◽  
Experimental Tests ◽  
Design Parameters ◽  
Parallel Kinematic Machine ◽  
Modeling Methodology ◽  
Parallel Kinematic ◽  
Stiffness Characteristics ◽  
And Performance ◽  
High Dynamics ◽  
Spring Constants

A three-revolute-prismatic-spherical parallel kinematic machine is proposed as an alternative solution for high-speed machining tool due to its high rigidity and high dynamics. Considering the parallel kinematic machine module as a typical compliant parallel mechanism, whose three limb assemblages have bending, extending and torsional deflections, this article proposes a hybrid modeling methodology to establish an analytical stiffness model for the three-revolute-prismatic-spherical device. The developed analytical model is further used to evaluate the stiffness mapping of the three-revolute-prismatic-spherical module over a given work plane which is then validated by experimental tests. The simulations and experiments indicate that the present hybrid methodology can predict the three-revolute-prismatic-spherical parallel kinematic machine’s stiffness in a quick and accurate manner. The solution for eigenvalue problem of the stiffness matrix leads to the stiffness characteristics of the parallel module including eigenstiffnesses and the corresponding eigenscrews as well as the equivalent screw spring constants. Based on the eigenscrew decomposition, the parallel kinematic machine is physically interpreted as a rigid platform suspending by six screw springs. The minimum, maximum and average of the screw spring constants are chosen as indices to assess the three-revolute-prismatic-spherical parallel kinematic machine’s stiffness performance. The distributions of the proposed indices throughout the workspace reveal a strong dependency on the mechanism’s configurations. At the final stage, the effects of some design parameters on system stiffness characteristics are investigated with the purpose of providing useful information for the conceptual design and performance improvement of the parallel kinematic machine.

A modified elasto-dynamic model based static stiffness evaluation for a 3-PRS PKM

2015 ◽  
Vol 230 (3) ◽  
pp. 353-366 ◽  
Author(s):  
Yan-Qin Zhao ◽  
Jun Zhang ◽  
Ling-Yan Ruan ◽  
Hai-Wei Luo ◽  
Xiao-Liu Yu
Keyword(s):  
Dynamic Model ◽  
Stiffness Matrix ◽  
Performance Enhancement ◽  
Element Formulation ◽  
Parallel Kinematic Machine ◽  
Design Variables ◽  
Parallel Kinematic ◽  
And Performance ◽  
Global Stiffness Matrix ◽  
Spring Constants

This paper proposes a modified elasto-dynamic model for a three-prismatic revolute spherical parallel kinematic machine, in which the flexibility of the prismatic revolute spherical limb structures are accounted in and modeled as a hollowed spatial beam with nonuniform cross section. The governing equations are derived through substructure synthesis and finite element formulation. The stiffness matrix of the platform is then extracted from global stiffness matrix and its characteristics at typical configurations are calculated to reveal complicated coupling effects of diagonal and nondiagonal elements of the stiffness matrix. The concept of principle stiffness and coupled stiffness are proposed and their distributions over the workspace are predicted with numerical simulations in a quick manner. Then the stiffness of the platform is physically interpreted as a kinematically unconstrained rigid body suspended by six screw springs with equivalent spring constants and pitches through eigenscrew decomposition. The distributions of screw spring constants over the workspace are then plotted to demonstrate a duality property. At last, the effects of some design variables such as structural and dimensional parameters on system rigidity performance are investigated with the purpose of providing useful information for the structural design and performance enhancement of the parallel kinematic machine.

Modal Analysis and Modeling of a Parallel Kinematic Machine

1999 ◽  
Author(s):  
David S. Hardage ◽  
Gloria J. Wiens
Keyword(s):  
Finite Element ◽  
Resonant Frequency ◽  
Structural Dynamics ◽  
Preliminary Data ◽  
Element Model ◽  
Parallel Kinematic Machine ◽  
Parallel Kinematic ◽  
Machine Configuration ◽  
Stiffness Characteristics ◽  
The Finite Element Model

Abstract This paper presents the results of a mini-modal survey on the Hexel Tornado 2000, a parallel kinematic machine tool located at Sandia National Laboratories, and discusses the finite element model that is used to simulate the structural dynamics of this machine. Preliminary data suggests a dependency of resonant frequency and stiffness characteristics on machine configuration.

Thermomechanical Interaction Between Thin Bare-Die Package and Thermal Solution in Next-Generation Mobile Computing Platforms

2019 ◽  
Vol 141 (1) ◽  
Author(s):  
Aastha Uppal ◽  
Jerrod Peterson ◽  
Je-Young Chang ◽  
Xi Guo ◽  
Frank Liang ◽  
...  
Keyword(s):  
Design Parameters ◽  
Next Generation ◽  
Mobile Platforms ◽  
Robust Modeling ◽  
Modeling Methodology ◽  
Bga Packages ◽  
Thermal Solution ◽  
Computing Platforms ◽  
And Performance ◽  
On Chip

The demands for both thinner bare-die ball grid array (BGA) packages and thinner thermal solutions have added complexity for the thermal enabling design and material options associated with system on chip packages in mobile personal computer (PC) platforms. The thermomechanical interactions between the bare-die package and the thermal solution are very critical, creating the needs for: (1) an in-depth thermomechanical characterization to understand their impacts on product quality and performance and (2) a simple and yet robust modeling methodology to analyze design parameters using a commercially available software. In this paper, experimental metrologies and modeling methodology are developed with the details of contents documented. Validation of the newly developed tools and recommendation/guidance are also discussed for detailed assessments of thermomechanical tradeoffs for optimal design spaces for next-generation mobile platforms.

Research and Development of Minitype Twin-Bladed Air Turbine

2009 ◽  
Author(s):  
Shih-Chun Wang ◽  
Kuang-Yuh Huang
Keyword(s):  
High Speed ◽  
Turbine Blades ◽  
Design Parameters ◽  
Operational Parameters ◽  
Micro Fabrication ◽  
Air Turbine ◽  
Speed Performance ◽  
Operational Energy ◽  
And Performance

In order to improve the machining efficiency of ultra-precision and micro fabrication technology, a high speed spindle is essential for the minitype tools widely applied in systems such as PCB drilling machines, micro fabrication machines, dental handpieces, etc. To realize the high speed performance, the air driven turbine is verified to be more feasible than the electromagnetic actuator. Furthermore, the operational efficiency and quality of the high speed spindle are significantly influenced by the turbine blades and the bearings respectively. Through detailed configurational studies and performance analyses on diverse minitype turbine blades, we have derived the efficiency- and quality-influential parameters. And based on optimization results, we have developed a novel type of twin bladed air turbine (TB-air turbine), which consists of two parallel blades with an angular offset. The offseted twin blades can efficiently and smoothly transform pneumatic energy into rotational energy. Therefore, steady driving force and less dynamic unbalance are able to be easily achieved for reducing nervous disturbances such as vibration, noise, and wear. By applying finite element analytical method, the operational performances and quality of the new developed twin bladed air turbine such as rotational speed, torque, vibration and noise were analyzed for comprehending influences of the design parameters and the operational parameters. While the inlet angle, the blade shape and its geometric parameters are the dominant design parameters; the inlet pressure and mass flow rate, and the outlet pressure are the main operational parameters. Through the turbine blades, the pneumatic energy will be transformed into operational energy in form of the flow field and the pressure distribution and the energy loss in form of turbulence. Also by integrating knowledge of production technology, a neat design of the turbine blades suitable for automatic manufacturing process is developed. And furthermore, through an elaborate layout of the flow guiding, a minimum rotational runout can be effectively achieved without any complicate and costly dynamic balancing process. Consequently, it has significantly depressed the stream noise and raised the operation lifetime of bearings. According to our experimental verification, the vibration and the stream noise of our TB-air turbines are 60% and 50% lower than traditional counterparts respectively. Our developed minitype spindle with novel TB-air turbine can efficiently realize high speed rotation with high torque, less vibration and less noise.

Comparative Analysis of a Redundant Pentapod Parallel Kinematic Machine

2015 ◽  
Vol 7 (3) ◽  
Author(s):  
Arta Alagheband ◽  
Masih Mahmoodi ◽  
James K. Mills ◽  
Beno Benhabib
Keyword(s):  
Comparative Analysis ◽  
Dynamic Stiffness ◽  
Degree Of Freedom ◽  
Parallel Kinematic Machine ◽  
High Stiffness ◽  
Parallel Kinematic ◽  
Parallel Kinematic Mechanisms ◽  
Stiffness Characteristics ◽  
Kinematic Mechanisms ◽  
Platform Tilt

Parallel kinematic mechanisms (PKMs) provide high stiffness and compact structures that are suitable for a large number of applications, including 5-axis milling. This paper presents a new pentapod-based PKM with an additional redundant degree-of-freedom (DOF) capable of reaching platform tilt angles of at least 90 deg over a large workspace. The proposed new PKM has a 6DOF 4 × SPRR + 1 × PSPR architecture. It is compared herein to Metrom® Pentapod as well as to several other pertinent PKMs in terms of workspace and dynamic stiffness. It is shown that the proposed mechanism can yield a tangibly larger workspace volume, when compared to those PKMs, while maintaining its high stiffness characteristics.

scholarly journals Kinematic Analysis and Trajectory Planning of the Orthoglide 5-Axis

2015 ◽  
Author(s):  
S. Caro ◽  
D. Chablat ◽  
P. Lemoine ◽  
P. Wenger
Keyword(s):  
Trajectory Planning ◽  
Kinematic Analysis ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Inverse Kinematic ◽  
Hybrid Architecture ◽  
Parallel Kinematic Machine ◽  
Control Loop ◽  
Parallel Kinematic

The subject of this paper is about the kinematic analysis and the trajectory planning of the Orthoglide 5-axis. The Orthoglide 5-axis a five degrees of freedom parallel kinematic machine developed at IRCCyN and is made up of a hybrid architecture, namely, a three degrees of freedom translational parallel manipulator mounted in series with a two degrees of freedom parallel spherical wrist. The simpler the kinematic modeling of the Orthoglide 5-axis, the higher the maximum frequency of its control loop. Indeed, the control loop of a parallel kinematic machine should be computed with a high frequency, i.e., higher than 1.5 MHz, in order the manipulator to be able to reach high speed motions with a good accuracy. Accordingly, the direct and inverse kinematic models of the Orthoglide 5-axis, its inverse kinematic Jacobian matrix and the first derivative of the latter with respect to time are expressed in this paper. It appears that the kinematic model of the manipulator under study can be written in a quadratic form due to the hybrid architecture of the Orthoglide 5-axis. As illustrative examples, the profiles of the actuated joint angles (lengths), velocities and accelerations that are used in the control loop of the robot are traced for two test trajectories.

Design Parameter Sensitivity for a Mountain Bike Rear Shock

2006 ◽  
Author(s):  
Robin C. Redfield
Keyword(s):  
High Speed ◽  
Current Trend ◽  
Graph Model ◽  
Bond Graph ◽  
Design Parameters ◽  
Mountain Biking ◽  
Mountain Bike ◽  
Suspension Systems ◽  
Experimental Response ◽  
And Performance

As the sport of mountain biking matures, equipment continually evolves to afford better biking performance, enjoyment, and safety. In the arena of suspension systems, mountain bikes have moved from rigid suspensions with large, knobby tires to front fork suspensions, and finally full suspensions. Suspensions have gone from elastomeric compliance to air and coil springs with adjustable travel. Damping has progressed from fixed to adjustable rebound, compression, and lockout. The current trend is to add force or frequency dependent damping to minimize response of a suspension from pedal input. A bond graph model of a mountain bike rear shock is developed incorporating adjustable rebound and low-speed compression, high-speed compression, and rider controlled, compression damping initiation. An air shock with a nitrogen charge is modeled with velocity across the shock as input. The dynamic equations that come from the bond graph are simulated to predict key forces, pressures, and flow-rates. Experimental response (forces, displacements, and velocities) of the modeled shock is acquired subject to periodic velocity inputs. The experimental response is used to tune the design parameters of the model and for validation. A sensitivity analysis is then undertaken to determine how significant key design parameters are to the performance of the shock. Once validated, the model is used to better understand the physics and performance of the mountain bike shock and to relate performance to the requirements of expert mountain bikers.

scholarly journals Technology-Oriented Optimization of the Secondary Design Parameters of Robots for High-Speed Machining Applications

2010 ◽  
Author(s):  
Se´bastien Briot ◽  
Anatol Pashkevich ◽  
Damien Chablat
Keyword(s):  
Machine Tools ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Parallel Robots ◽  
Design Parameters ◽  
Speed Up ◽  
Parallel Kinematic ◽  
Parallel Kinematic Machine Tools ◽  
Accuracy Constraints ◽  
Three Degrees Of Freedom

In this paper, a new methodology for the optimal design of the secondary geometric parameters (shape of links, size of the platform, etc.) of parallel kinematic machine tools is proposed. This approach aims at minimizing the total mass of the robot under position accuracy constraints. This methodology is applied to two translational parallel robots with three degrees-of-freedom (DOF): the Y-STAR and the UraneSX. The proposed approach is able to speed up the design process and to help the designer to find more quickly a set of design parameters.

An Analysis of Rigid Sidewall Surface Effect Craft for High-Speed Personnel Transportation

1970 ◽  
Vol 7 (01) ◽  
pp. 55-68
Author(s):  
Eugene R. Miller
Keyword(s):  
High Speed ◽  
Surface Effect ◽  
Transportation Cost ◽  
Total Power ◽  
Design Parameters ◽  
Economic Criterion ◽  
Calm Water ◽  
And Performance ◽  
Commercial Applications ◽  
Sidewall Surface

A number of commercial applications have been proposed for rigid sidewall surface effect craft. The transport of crews to offshore operations is an application which is well-suited to the immediate use of moderately sized craft of this type. Because the crews are paid while they are in transit, high speeds are required to minimize the total transportation costs. The characteristics and performance of rigid sidewall surface effect craft suitable for crew transport operations are developed. The major design parameters studied include pay-load, total power, and machinery type. Performance estimates are made for operations in both calm water and waves. An economic model is developed to simulate crewboat operations. Cost estimates are based on current technology and price levels. The total unit transportation cost is used as the economic criterion in the determination of the relative merit of various craft. For the purpose of comparison the characteristics and costs of planing hull crewboats for the same mission are developed. It is concluded that rigid sidewall surface effect craft have the potential of being economically superior to planing boats for crew transport operations.

scholarly journals Sensitivity Analysis of the Orthoglide, a 3-DOF Translational Parallel Kinematic Machine

2004 ◽  
Author(s):  
Ste´phane Caro ◽  
Philippe Wenger ◽  
Fouad Bennis ◽  
Damien Chablat
Keyword(s):  
Sensitivity Analysis ◽  
Kinematic Analysis ◽  
Design Parameters ◽  
Analysis Method ◽  
Parallel Kinematic Machine ◽  
Vector Method ◽  
End Effector ◽  
Singular Configurations ◽  
Parallel Kinematic ◽  
Position And Orientation

This paper presents a sensitivity analysis of the Orthoglide, a 3-DOF translational Parallel Kinematic Machine. Two complementary methods are used to analyze its sensitivity to its dimensional and angular variations. First, a linkage kinematic analysis method is used to have a rough idea of the influence of the dimensional variations on the location of the end-effector, and shows that the variations in design parameters of the same type from one leg to another one have the same influence on the end-effector. However, this method does not allow the designer to know the influence of the variations in the parallelograms. Thus, a differential vector method is used to study the influence of the dimensional and angular variations in the parts of the manipulator, and particularly the variations in the parallelograms, on the position and orientation of the end-effector. It turns out that the isotropic kinematic configuration of the manipulator is the least sensitive one to its geometrical variations, contrary to the closest configurations to its kinematic singular configurations, which are the most sensitive to geometrical variations.

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