Development of a DVD pickup-based four-degrees- of-freedom motion error measuring system for a single-axis linear moving platform

2009 ◽  
Vol 224 (1) ◽  
pp. 37-50 ◽  
Author(s):  
H-L Huang ◽  
C-H Liu ◽  
W-Y Jywe ◽  
M-S Wang ◽  
Y-R Jeng ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Measuring System ◽  
Motion Error ◽  
Moving Platform

Homing Sensor System Design for a 2D Long Range Nanopositioning Moving Platform

2014 ◽  
Vol 615 ◽  
pp. 57-62 ◽  
Author(s):  
Raquel Acero Cacho ◽  
Jose Antonio Albajez ◽  
José Antonio Yagüe-Fabra ◽  
Marta Torralba ◽  
Margarita Valenzuela ◽  
...  
Keyword(s):  
Sensor System ◽  
Measuring System ◽  
Experimental Characterization ◽  
Measuring Systems ◽  
Precision Measuring ◽  
Atomic Force ◽  
Ultra Precision ◽  
Moving Platform ◽  
Sensor System Design

The nanotechnology field has been developing strongly in recent years and ultra-precision measuring systems are nowadays required. A new two-dimensional moving platform with 50x50 mm range of travel, nanometer resolution and sub micrometer accuracy is being designed by the authors in order to be integrated with an Atomic Force Microscope (AFM). In this work the definition, design and experimental characterization of a homing sensor system for this 2D moving platform is presented. The homing sensor system will allow the generation of an absolute 2D reference for the platform (X-Y axis and θz rotation), defining an initial cero for the measuring system, which is based on laser encoders.

scholarly journals Simultaneous Measurement Method and Error Analysis of the Six Degrees-of-Freedom Motion Errors of a Rotary Axis

2018 ◽  
Vol 8 (11) ◽  
pp. 2232 ◽  
Author(s):  
Chuanchen Bao ◽  
Qibo Feng ◽  
Jiakun Li
Keyword(s):  
Simultaneous Measurement ◽  
Error Compensation ◽  
Degrees Of Freedom ◽  
Translational Motion ◽  
Laser Interferometry ◽  
Positioning Error ◽  
Motion Error ◽  
Measuring Device ◽  
Six Degrees Of Freedom ◽  
Rotary Axis

Error measurement of a rotary axis is the key to error compensation and to improving motion accuracy. However, only a few instruments can measure all the motion errors of a rotary axis. In this paper, a device based on laser collimation and laser interferometry was introduced for simultaneous measurement of all six degrees-of-freedom motion errors of a rotary axis. Synchronous rotation of the target and reference rotary axes was achieved by developing a proportional–integral–derivative algorithm. An error model for the measuring device was established using a homogeneous transformation matrix. The influences of installation errors, manufacturing errors, and error crosstalk were studied in detail, and compensation methods for them were proposed. After compensation, the repeatability of axial and radial motion errors was significantly improved. The repeatability values of angular positioning error and of tilt motion error around the y axis and x axis were 28.0″, 2.8″, and 3.9″. The repeatability values of translational motion errors were less than 2.8 μm. The comparison experiments show that the comparison errors of angular positioning error and tilt motion error around the y axis were 2.3″ and 2.9″, respectively. These results demonstrate the effectiveness of our method and the error compensation model.

Dynamic Modeling of a Parallel Manipulator With Three Translational Degrees of Freedom

1998 ◽  
Author(s):  
Richard Stamper ◽  
Lung-Wen Tsai
Keyword(s):  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Close Agreement ◽  
Jacobian Matrix ◽  
Parallel Manipulators ◽  
Kinematic Structure ◽  
End Effector ◽  
Moving Platform ◽  
Euler Approach ◽  
Computationally Intensive

Abstract The dynamics of a parallel manipulator with three translational degrees of freedom are considered. Two models are developed to characterize the dynamics of the manipulator. The first is a traditional Lagrangian based model, and is presented to provide a basis of comparison for the second approach. The second model is based on a simplified Newton-Euler formulation. This method takes advantage of the kinematic structure of this type of parallel manipulator that allows the actuators to be mounted directly on the base. Accordingly, the dynamics of the manipulator is dominated by the mass of the moving platform, end-effector, and payload rather than the mass of the actuators. This paper suggests a new method to approach the dynamics of parallel manipulators that takes advantage of this characteristic. Using this method the forces that define the motion of moving platform are mapped to the actuators using the Jacobian matrix, allowing a simplified Newton-Euler approach to be applied. This second method offers the advantage of characterizing the dynamics of the manipulator nearly as well as the Lagrangian approach while being less computationally intensive. A numerical example is presented to illustrate the close agreement between the two models.

scholarly journals Kinetostatic Analysis of a Simple Cable-Driven Parallel Crane

2018 ◽  
Author(s):  
Saman Lessanibahri ◽  
Philippe Cardou ◽  
Stéphane Caro
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Performance ◽  
Static Equilibrium ◽  
Bridge Crane ◽  
Static Models ◽  
Moving Platform ◽  
Simple Assembly

This paper introduces the concept of a new planar Cable-Driven Parallel Crane (CDPC) for lifting and carrying payloads with a moving hoist mechanism connected in parallel to the ceiling. In contrast to bridge-crane, CDPC is inexpensive and practicable for diverse tasks with simple assembly setup. The hoist mechanism is an under-constrained moving-platform articulated through a bi-actuated cable circuit, namely, a cable loop. The hoist is connected to a suspended moving-platform with four degrees of freedom. The power is transmitted directly from the motors fixed on frames to the hoist through the cable loop. Therefore, the dynamic performance of the robot is increased due to lower inertia of the moving-platform. However, the moving-platform undergoes some parasitic inclinations because of the cable loop. This paper investigates the parasitic inclination and its effect on the positioning of the payload. The workspace of the CDPC is studied in terms of static equilibrium. Moreover, the geometrico-static and elasto-static models of the CDPC are presented.

scholarly journals Reconfiguration Analysis of a 3-DOF Parallel Mechanism

Robotics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 66
Author(s):  
Maurizio Ruggiu ◽  
Xianwen Kong
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Operation Mode ◽  
Parallel Mechanisms ◽  
Universal Joint ◽  
Kinematic Chains ◽  
Constraint Equations ◽  
The Third ◽  
Equilateral Triangles ◽  
Moving Platform

This paper deals with the reconfiguration analysis of a 3-DOF (degrees-of-freedom) parallel manipulator (PM) which belongs to the cylindrical parallel mechanisms family. The PM is composed of a base and a moving platform shaped as equilateral triangles connected by three serial kinematic chains (legs). Two legs are composed of two universal (U) joints connected by a prismatic (P) joint. The third leg is composed of a revolute (R) joint connected to the base, a prismatic joint and universal joint in sequence. A set of constraint equations of the 1-RPU−2-UPU PM is derived and solved in terms of the Euler parameter quaternion (a.k.a. Euler-Rodrigues quaternion) representing the orientation of the moving platform and of the Cartesian coordinates of the reference point on the moving platform. It is found that the PM may undergo either the 3-DOF PPR or the 3-DOF planar operation mode only when the base and the moving platform are identical. The transition configuration between the operation modes is also identified.

Kinematic and Dynamic Analysis of a Two-Degree-of-Freedom Spherical Wrist

2010 ◽  
Vol 2 (3) ◽  
Author(s):  
M. Ruggiu
Keyword(s):  
Condition Number ◽  
Performance Index ◽  
Degrees Of Freedom ◽  
Kinematic Chain ◽  
Scanning System ◽  
Spherical Wrist ◽  
Moving Platform ◽  
Two Degree Of Freedom ◽  
Spherical Motion ◽  
Motion Generator

The present paper proposes the analysis of a spherical wrist with two degrees of freedom for scanning system applications. The wrist consists of two chains of revolute-revolute pairs. A slotted arc connecting the two chains behaves as a further revolute pair. Thus, the mechanism is an overconstrained (meaning of this definition is discussed in this work) single-loop kinematic chain composed of five revolute pairs equivalent to a spherical motion generator since all its axes intersect at a point. Throughout the paper, the kinematic analysis is developed including some details about the workspace, which depends on the design of the slotted arc. The performance index given as the inverse of the condition number is used to measure the performances of the motion of the moving platform of the wrist. The singularity poses found were examined in detail. A simplified dynamic model is proposed that provides the torques suitable for satisfying a given kinematics. Finally, the paper presents a motorized hardware model of the mechanism assembled in the laboratory.

Austrian Track Testing and Recording Car EM 250: Source for Wheel-Rail Interaction Analysis

2000 ◽  
Vol 1713 (1) ◽  
pp. 22-28
Author(s):  
Gerard Presle ◽  
Werner Hanreich ◽  
Paul Mittermayr
Keyword(s):  
Binary Data ◽  
Degrees Of Freedom ◽  
Interaction Analysis ◽  
Quality Parameters ◽  
Measuring System ◽  
Rolling Stock ◽  
Ride Quality ◽  
Track Geometry ◽  
The Impact ◽  
Track Quality

The dynamic behavior and ride quality of railway vehicles are influenced by track quality. Monitoring riding comfort and safety is a major task of the Austrian Federal Railway’s Infrastructure Division. The track testing and recording car EM 250 provides a proven measuring instrument for modern track maintenance. Equipped with an inertial measuring system and an optical track gauge measuring system, the track testing and recording car can measure the track alignment and rail profiles at speeds of up to 220 km/h. The measurements, taken every 25 cm, provide binary data files that can be processed offline. Track quality parameters are measured as functions of vehicle acceleration and are stored in a database from which they can be easily retrieved from any computer in the company. The Bureau for Applied Mechanics and Mathematics was commissioned by the Austrian Federal Railways to develop the SIMULAT program for analyzing rolling stock dynamics. In developing the model, special consideration was given to the exact mathematical description of all elements affecting vehicle dynamics. Using an optical measuring system, the track testing and recording car determines the rail cross section on the basis of readings at individual points. The simulation program links the curve with the track data, allowing the analysis of the impact of worn profiles on running stability. For the simulation, the line layout and the track geometry deviations excite the model of track and vehicle. In a followup phase, the vector of generalized degrees of freedom is evaluated, and the results are displayed with a visualization program. The simulation results were compared with data recorded during a test run and showed satisfactory correspondence.

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