scholarly journals Spatial Straight-Line Linkages by Factorization of Motion Polynomials

2015 ◽  
Vol 8 (2) ◽  
Author(s):  
Zijia Li ◽  
Josef Schicho ◽  
Hans-Peter Schröcker
Keyword(s):  
End Effector ◽  
Single Loop ◽  
Revolute Joints ◽  
Straight Line ◽  
Prismatic Joints ◽  
Spatial Linkages ◽  
Line Trajectory ◽  
Straight Line Trajectory

We use the recently introduced factorization of motion polynomials for constructing overconstrained spatial linkages with a straight-line trajectory. Unlike previous examples of such linkages by other authors, they are single-loop linkages and the end-effector motion is not translational. In particular, we obtain a number of linkages with four revolute and two prismatic joints and a remarkable linkage with seven revolute joints one of whose joints performs a Darboux motion.

Determination of Joint Velocities of Robots by Using Screws

1984 ◽  
Vol 106 (2) ◽  
pp. 222-227 ◽  
Author(s):  
K. Sugimoto
Keyword(s):  
Screw Theory ◽  
Sampling Period ◽  
Trajectory Control ◽  
Orthogonal Basis ◽  
Industrial Robots ◽  
End Effector ◽  
Straight Line ◽  
Line Trajectory ◽  
Straight Line Trajectory

The screw theory is applied to determination of joint velocities of robot arms. The method described in this paper can be directly used for the straight line trajectory control of existing industrial robots. Joint velocities are computed by taking inner products of two kinds of screws, one of which is an element of an orthogonal basis of the screw system composed of joint screws and another is the screw representing an instantaneous motion of an end effector. The computation can be performed during a sampling period while a robot is in motion.

Optimal Synthesis and Analysis of a New Leg Mechanism: The Planetary Gear Leg

1992 ◽  
Author(s):  
Ning-Xin Chen ◽  
Shin-Ming Song
Keyword(s):  
Planetary Gear ◽  
Optimization Method ◽  
Maximum Deviation ◽  
Walking Machine ◽  
Straight Line ◽  
Force Moment ◽  
Good Energy ◽  
Line Trajectory ◽  
Leg Design ◽  
Straight Line Trajectory

Abstract The leg mechanism of a walking machine has a strong influence on the performance of the machine. A successful leg mechanism should be energy efficient, compact in size, strong and simple. In order to achieve good energy efficiency, a walking machine leg should be able to generate an exact or approximate straight line at the foot with only one driving actuator. This paper deals with the synthesis and analysis of a new leg mechanism — the planetary gear leg mechanism. Four types of planetary gear legs are studied. By the SUMT optimization method, a 20 inch tall leg is able to generate an approximate straight line trajectory with a maximum deviation of 0.12805 inches in a 20 inch stroke. The direct and inverse kinematics and velocities of the legs are analyzed. Also, the distribution of actuator force/moment during walking are studied. The results show that this leg design has great potential to be used as a practical walking machine leg.

A non-overconstrained variant of the Agile Eye with a special decoupled kinematics

Robotica ◽  
2013 ◽  
Vol 32 (6) ◽  
pp. 889-905 ◽  
Author(s):  
Chin-Hsing Kuo ◽  
Jian S. Dai ◽  
Giovanni Legnani
Keyword(s):  
Angular Displacement ◽  
Universal Joint ◽  
Special Configuration ◽  
End Effector ◽  
Revolute Joint ◽  
Revolute Joints ◽  
Prismatic Joints ◽  
Decoupled Motion ◽  
Orientation Mechanism ◽  
Actuated Joints

SUMMARYA non-overconstrained three-DOF parallel orientation mechanism that is kinematically equivalent to the Agile Eye is presented in this paper. The output link (end-effector) of the mechanism is connected to the base by one spherical joint and by another three identical legs. Each leg comprises of, in turns from base, a revolute joint, a universal joint, and three prismatic joints. The three lower revolute joints are active joints, while all other joints are passive ones. Based on a special configuration, some three projective angles of the end-effector coordinates are fully decoupled with respect to the input actuated joints, that is, by actuating any revolute joint the end-effector rotates in such a way that the corresponding projective angle changes with the same angular displacement. The fully decoupled motion is analyzed geometrically and proved theoretically. Besides, the inverse and direct kinematics solutions of the mechanism are provided based on the geometric reasoning and theoretical proof.

Effect of vibrating feeder pan geometry on radiometric separator performance

2020 ◽  
pp. 39-42
Author(s):  
S. V. Tereshchenko ◽  
◽  
D. N. Shibaeva ◽  
P. A. Shumilov ◽  
B. A. Vlasov ◽  
...  
Keyword(s):  
Operating Conditions ◽  
Central Axis ◽  
Linear Distribution ◽  
Motion Trajectories ◽  
Triangular Shape ◽  
Straight Line ◽  
Line Trajectory ◽  
The Mathematical Model ◽  
Straight Line Trajectory ◽  
Vibrating Feeder

The article offers justifies the optimized shape for the vibrating feeder pan of a radiometric separator, which ensures the maximum travelling speed and uniform flow of ore material in the zone of radiation and recording. Three shapes of pans are discussed: rectangular, parabolic and triangular. It is found that motion of ore material along an inclined rectangular-shape pan is straight-linear. Distribution of ore particles along the width of the channel, which governs the scatter of the motion trajectories relative to the central axis of the channel, depends on the runoff point of particles from the outlet feeder. Proposed for the description of the motion trajectory of ore particles along an inclined channel of parabolic shape, the mathematical model demonstrates the curved and pendulum-wise motion of an ore particle with the attenuating amplitude. The motion of an ore particle in an inclined pan with the triangular-shape channel features the minimized scatter of motion trajectories relative to the central axis of the channel. The analysis of ore motion along vibrating feeder pans with different shape channels is carried out in Rocky DEM environment with regard to interaction of ore particles with the pan surface and with each other. The simulation modeling has proved the conclusions on the efficiency of the triangularshape profile of the vibrating feeder pan as it ensures uniform single-row flow of ore particles along the straight-line trajectory. The triangular shape of the pan contributes to the increased travelling speed of ore particles and, accordingly, to the enhanced capacity of the separator. The radiometric separator efficiency can be increased 1.5 times by changing from the parabolicshape channels to the triangular-shape profiles of vibrating feeder pans at the other operating conditions of radiometric separators being equal.

Dynamic Modeling and Analysis of a Two D.O.F. Mobile Manipulator

2000 ◽  
Author(s):  
D. Naderi ◽  
A. Meghdari ◽  
M. Durali
Keyword(s):  
Dynamic Modeling ◽  
Degrees Of Freedom ◽  
Ground Surface ◽  
Mobile Manipulator ◽  
Two Degrees Of Freedom ◽  
Modeling And Analysis ◽  
Straight Line ◽  
Fixed Reference ◽  
Line Trajectory ◽  
Straight Line Trajectory

Abstract This paper presents the kinematic and dynamic modeling of a two degrees of freedom manipulator attached to a vehicle with a two degrees of freedom suspension system. The vehicle is considered to move with a constant linear speed over an irregular ground-surface while the end-effector tracks a desired trajectory in a fixed reference frame. In addition, the effects of highly coupled dynamic interaction between the manipulator and vehicle (including the suspension system’s effects) have been studied. Finally, simulation results for the end-effector’s straight-line trajectory are presented to illustrate these effects.

Dynamic Interaction Between the Manipulator and Vehicle of a Mobile Manipulator

1999 ◽  
Author(s):  
A. Meghdari ◽  
M. Durali ◽  
D. Naderi
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Interaction ◽  
Suspension System ◽  
Mobile Manipulator ◽  
Moving Vehicle ◽  
Straight Line ◽  
Fixed Reference ◽  
Line Trajectory ◽  
Time And Energy ◽  
Straight Line Trajectory

Abstract A manipulator mounted on a moving vehicle is called a mobile manipulator. A mobile manipulator with an appropriate suspension system can pass over uneven surfaces, thus having an infinite workspace. If the manipulator could operate while the vehicle is traveling, the efficiency concerning with the time and energy used for stopping and starting will be increased. This paper presents the kinematics and dynamic modeling of a one degree of freedom manipulator attached to a vehicle with a two degrees of freedom suspension system. The vehicle is considered to move with a constant linear speed over an uneven surface while the end effector tracks a desired trajectory in a fixed reference frame. In addition, the effects of dynamic interaction between the manipulator and vehicle (including the suspension system’s effects) have been studied. Simulation results from straight line trajectory are presented to illustrate these effects.

Image Reconstruction Based on TV Minimization and OS-EM Method in Linear Scan CT

2013 ◽  
Vol 684 ◽  
pp. 402-405
Author(s):  
Bin Yan ◽  
Ai Long Cai ◽  
Feng Wei ◽  
Lei Li ◽  
Xiao Qi Xi
Keyword(s):  
Computed Tomography ◽  
Reconstruction Algorithm ◽  
High Accuracy ◽  
Total Variation Minimization ◽  
Remarkable Improvement ◽  
Straight Line ◽  
Em Method ◽  
Minimization Technique ◽  
Line Trajectory ◽  
Straight Line Trajectory

A straight-line trajectory computed tomography (CT) has been investigated in this paper and a high accuracy reconstruction algorithm based on TV minimization and OS-EM method has been put forward. This new algorithm, which is called TV-OS-EM, takes the advantage of both statistic iterative algorithm OS-EM and the total variation minimization technique, and has an efficient property of de-noising and restoration. The numerical experimental results show that the new method can achieve a remarkable improvement in image quality.

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