scholarly journals Six-degree-of-freedom pose estimation with µm/µrad accuracy based on laser multilateration

2021 ◽  
Vol 10 (1) ◽  
pp. 19-24
Author(s):  
Jan Nitsche ◽  
Matthias Franke ◽  
Nils Haverkamp ◽  
Daniel Heißelmann
Keyword(s):  
Pose Estimation ◽  
Coordinate Measuring Machine ◽  
Degree Of Freedom ◽  
End Effector ◽  
Data Rates ◽  
Measurement Principle ◽  
Measuring Machine ◽  
Position And Orientation ◽  
Six Degree Of Freedom ◽  
Adequate Measurement

Abstract. The estimation of the six-degree-of-freedom position and orientation of an end effector is of high interest in industrial robotics. High precision and data rates are important requirements when choosing an adequate measurement system. In this work, a six-degree-of-freedom pose estimation setup based on laser multilateration is described together with the measurement principle and self-calibration strategies used in this setup. In an experimental setup, data rates of 200 Hz are achieved. During movement, deviations from a reference coordinate measuring machine of 20 µm are observed. During standstill, the deviations are reduced to 5 µm.

Structural Parameters Which Reduce the Number of Manipulator Configurations

1992 ◽  
Author(s):  
Constantinos Mavroidis ◽  
Bernard Roth
Keyword(s):  
General Class ◽  
Inverse Kinematics ◽  
Structural Parameters ◽  
Degree Of Freedom ◽  
Characteristic Polynomials ◽  
End Effector ◽  
Lower Maximum ◽  
Position And Orientation ◽  
Six Degree Of Freedom

Abstract The inverse kinematics of series-chain, six-degree-of-freedom manipulators has been developed to the point where it yields all possible configurations for a given end-effector position and orientation. In this paper we use the methods of inverse kinematics to uncover the conditions on the structural parameters which cause a manipulator to yield a lower maximum number of configurations than its general class. It is shown that the following conditions can cause a diminution In the maximum number of possible configurations: parallel joint axes, perpendicular joint axes, intersecting joint axes, and Bennett geometries. Using these geometries in 6R, 5R1P, 4R2P and 3R3P chains, this paper determines the reduction in degree of their characteristic polynomials.

Accurate Motion of a Robot End-Effector Using the Curvature Theory of Ruled Surfaces

1988 ◽  
Vol 110 (4) ◽  
pp. 383-388 ◽  
Author(s):  
B. S. Ryuh ◽  
G. R. Pennock
Keyword(s):  
Trajectory Planning ◽  
Interpolation Method ◽  
Ruled Surface ◽  
Degree Of Freedom ◽  
End Effector ◽  
Straight Path ◽  
Curvature Theory ◽  
Position And Orientation ◽  
Six Degree Of Freedom ◽  
Differential Properties

In robotics, there are two methods of trajectory planning: the joint interpolation method which is appropriate for fast transition of the robot end-effector; and the cartesian interpolation method which is appropriate for slower motion of the end-effector along straight path segments. Neither method, however, is sufficient to allow a smooth, differentiable, transition of position and orientation of the end-effector. In this paper, we propose a method of trajectory planning that will permit more accurate motion of a robot end-effector. The method is based on the curvature theory of a ruled surface generated by a line fixed in the end-effector, referred to as the tool line. The orientation of the end-effector about the tool line is included in the analysis to completely describe the six degree-of-freedom motion of the end-effector. The linear and angular properties of motion of the end-effector, determined from the differential properties of the ruled surface, are utilized in the trajectory planning.

Structural Parameters Which Reduce the Number of Manipulator Configurations

1994 ◽  
Vol 116 (1) ◽  
pp. 3-10 ◽  
Author(s):  
C. Mavroidis ◽  
B. Roth
Keyword(s):  
General Class ◽  
Inverse Kinematics ◽  
Structural Parameters ◽  
Degree Of Freedom ◽  
Characteristic Polynomials ◽  
End Effector ◽  
Lower Maximum ◽  
Position And Orientation ◽  
Six Degree Of Freedom

The inverse kinematics of series-chain, six-degree-of-freedom manipulators has been developed to the point where it yields all possible configurations for a given end-effector position and orientation. In this paper we use the methods of inverse kinematics to uncover the conditions on the structural parameters which cause a manipulator to yield a lower maximum number of configurations than its general class. It is shown that the following conditions can cause a diminution in the maximum number of possible configurations: parallel joint axes, perpendicular joint axes, intersecting joint axes, and Bennett geometries. Using these geometries in 6R, 5R1P, 4R2P, and 3R3P chains, this paper determines the reduction in degree of their characteristic polynomials.

Parameterization of Three-Dimensional Rigid Body Guidance Incorporating Planar Gear Connections in a Spatial Closed-Loop Mechanism With Parallel Consecutive Axes

2008 ◽  
Author(s):  
Javier Rolda´n Mckinley ◽  
Carl Crane ◽  
David B. Dooner
Keyword(s):  
Computer Animation ◽  
Closed Loop ◽  
Three Dimensional ◽  
Motion Generation ◽  
Repetitive Motion ◽  
End Effector ◽  
Spatial Mechanism ◽  
Joint Axis ◽  
Position And Orientation ◽  
Six Degree Of Freedom

This paper introduces a reconfigurable closed-loop spatial mechanism that can be applied to repetitive motion tasks. The concept is to incorporate five pairs of non-circular gears into a six degree-of–freedom closed-loop spatial chain. The gear pairs are designed based on given mechanism parameters and a user defined motion specification of a coupler link of the mechanism. It is shown in the paper that planar gear pairs can be used if the spatial closed-loop chain is comprised of six pairs of parallel joint axes, i.e. the first joint axis is parallel to the second, the third is parallel to the fourth, ..., and the eleventh is parallel to the twelfth. This paper presents the synthesis of the gear pairs that satisfy a specified three-dimensional position and orientation need. Numerical approximations were used in the synthesis the non-circular gear pairs by introducing an auxiliary monotonic parameter associated to each end-effector position to parameterize the motion needs. The findings are supported by a computer animation. No previous known literature incorporates planar non-circular gears to fulfill spatial motion generation needs.

Knee Joint Response to Compressive Loading and Ligament Injury

1999 ◽  
Author(s):  
Jordan Lee ◽  
Frank Fronczak
Keyword(s):  
Knee Joint ◽  
Cruciate Ligament ◽  
Compressive Loading ◽  
Degree Of Freedom ◽  
Ligament Injury ◽  
Ligament Injuries ◽  
Acl Injuries ◽  
Measuring Machine ◽  
Anterior Cruciate ◽  
Six Degree Of Freedom

Abstract The knee joint is a six degree-of-freedom joint which has a complex response to loading. The joint has a characteristic behavior for particular ligament injuries such as anterior cruciate ligament failure. The response of the joint to a combination of compressive loading and secondary loadings was examined in this study. The secondary loadings were: an anterior force, a valgus moment, an internal torque, or an external torque. A goat model was used with 17 specimens testing different ligament injuries in vitro, specifically stretched or severed anterior cruciate ligaments (ACL) and lateral collateral ligaments (LCL). The femur was held fixed and the tibia loaded in a specially designed apparatus, allowing complete six degree-of-freedom joint motion. The motion of the tibia with respect to the femur was recorded using a coordinate measuring machine. The knee joint demonstrated sensitivity to ACL injuries but not to LCL injuries for the loadings examined. The response to ACL injuries was more highly dependant on the compressive load than the secondary loadings for all tests.

Measurement Method for the Symmetry Error of Double Keyway in a Wheel Hub Bore

2010 ◽  
Vol 139-141 ◽  
pp. 2087-2092
Author(s):  
Xiao Ming Zhao ◽  
Yun Feng
Keyword(s):  
Measurement Method ◽  
Geometric Analysis ◽  
Coordinate Measuring Machine ◽  
Position Error ◽  
Minimum Condition ◽  
Engineering Practice ◽  
Error Evaluation ◽  
Measurement Principle ◽  
Measuring Machine ◽  
Error Formulas

In this paper, a new measurement method is presented, This method is to use a three-coordinate measuring machine (CMM) to test the symmetry error of double keyway in a wheel hub bore. According to the minimum condition criterion of form and position error evaluation, and making use of the minimum tolerance zone of position error evaluation, two symmetry error formulas of double keyway in a wheel hub bore are deduced by geometric analysis. The problems may be encountered when using the formulas in the practical application are discussed. These formulas solve the measurement principle problem of double keyway in the engineering practice. In the end an example is put forward to verify this method and the formulas.

scholarly journals Kinematics Simulation of Gough-Stewart Parallel Manipulator by Using Simulink Package in Matlab Software

2019 ◽  
Vol 27 (2) ◽  
pp. 10-20
Author(s):  
Hassan Mohammed Alwan ◽  
Riyadh Ahmed Sarhan
Keyword(s):  
Theoretical Model ◽  
Parallel Manipulator ◽  
Degree Of Freedom ◽  
Kinematics Analysis ◽  
Matlab Software ◽  
Kinematics Simulation ◽  
Moving Platform ◽  
Position And Orientation ◽  
Six Degree Of Freedom ◽  
Forward Equations

The Gough Stewart Robotic manipulator is a parallel manipulator with six-degree of freedom, which has six equations of Kinematics (Inverse and forward), with six variables (Lengths, Position, and Orientation). In this work derived the inverse equations, which used to compute the lengths of the linkages and its changes depended on the position and orientation of the platform's center, then derived the forward equations to calculate the position and orientation of the moving platform in terms of the lengths. This theoretical model of the kinematics analysis of the Gough Stewart has been built into the Simulink package in Matlab to obtain the lengths, position, and orientation for the manipulator at any time of motion. The input parameters (Position and Orientation) in inverse blocks compared with the output parameters (Position and Orientation) in the forward blocks, which show good results.

scholarly journals A Six Degree of Freedom Epicyclic-Parallel Manipulator

2012 ◽  
Vol 4 (4) ◽  
Author(s):  
Chao Chen ◽  
Thibault Gayral ◽  
Stéphane Caro ◽  
Damien Chablat ◽  
Guillaume Moroz ◽  
...  
Keyword(s):  
Inverse Kinematics ◽  
Parallel Manipulator ◽  
Degree Of Freedom ◽  
Kinematics Analysis ◽  
End Effector ◽  
Six Dof ◽  
Six Degree Of Freedom

A new six-dof epicyclic-parallel manipulator with all actuators allocated on the ground is introduced. It is shown that the system has a considerably simple kinematics relationship, with the complete direct and inverse kinematics analysis provided. Further, the first and second links of each leg can be driven independently by two motors. The serial and parallel singularities of the system are determined, with an interesting feature of the system being that the parallel singularity is independent of the position of the end-effector. The workspace of the manipulator is also analyzed with future applications in haptics in mind.

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