scholarly journals Dynamics and Control of a Novel 3 -DOF Parallel Manipulator with Actuation Redundancy

2013 ◽  
Vol 10 (6) ◽  
pp. 552-562 ◽  
Author(s):  
Xue-Mei Niu ◽  
Guo-Qin Gao ◽  
Xin-Jun Liu ◽  
Zhi-Da Bao
Author(s):  
Paolo Gallina ◽  
Aldo Rossi ◽  
Robert L. Williams

Abstract A hybrid parallel/serial manipulator architecture was introduced in a companion paper where the translational freedoms are provided by a cable-direct-driven robot (CDDR) and the rotational freedoms are provided by a serial wrist mechanism. While the companion paper presents kinematics and statics, the current paper presents a dynamics model and simulated control for planar CDDRs. Examples are presented to compare the planar 3-cable CDDR with one degree of actuation redundancy and the 4-cable CDDR with two degrees of actuation redundancy. It was found that the 4-cable tracking error was worse than for the 3-cable case, due to increased inertia with an additional actuator. Also, the controller architecture considers including and not including a feedforward reference acceleration term with the overall mass matrix; the performance of the controller with the feedforward term is clearly preferable.


1998 ◽  
Vol 122 (3) ◽  
pp. 299-303 ◽  
Author(s):  
Jose´ Marı´a Rico Martı´nez ◽  
Joseph Duffy

Simple expressions for the forward and inverse acceleration analyses of a six degree of freedom in-parallel manipulator are derived. The expressions are obtained by firstly computing the “accelerator” for a single Hooke-Prismatic-Spheric, HPS for short, connector chain in terms of the joint velocities and accelerations. The accelerator is a function of the line coordinates of the joint axes and of a sequence of Lie products of the same line coordinates. A simple expression for the acceleration of the prismatic actuator is obtained by forming the Klein form, or reciprocal product, with the accelerator and the coordinates of the line of the connector chain. Since the Klein form is invariant, the resulting expression can be applied directly to the six HPS connector chains of an in-parallel manipulator. As a required intermediate step, this contribution also derives the corresponding solutions for the forward and inverse velocity analyses. The authors believe that this simple method has applications in the dynamics and control of these in-parallel manipulators where the computing time must be minimized to improve the behavior of parallel manipulators. [S1050-0472(00)01303-9]


Author(s):  
José María Rico Martínez ◽  
Joseph Duffy

Abstract A very simple novel expression for the accelerations of the six prismatic actuators, of the HPS connector chains, of a 6 degree of freedom in-parallel manipulator is derived. The expression is obtained by firstly computing the “accelerator” for a single HPS connector chain in terms of the joint velocities and accelerations. The accelerator is a function of the line coordinates of the joint axes and of a sequence of Lie products of the same line coordinates. A simple expression for the acceleration of the prismatic actuator is obtained by forming the Klein form, or reciprocal product, with the accelerator and the coordinates of the line of the connector chain. Since the Klein form is invariant, the resulting expression can be applied directly to the six HPS connector chains of an in-parallel manipulator. The authors believe that this simple method has important applications in the dynamics and control of these in-parallel manipulators where the computing time must be minimized to improve the behavior of parallel manipulators.


2018 ◽  
Vol 4 (5) ◽  
pp. 7
Author(s):  
Shivam Dwivedi ◽  
Prof. Vikas Gupta

As the four-wheel steering (4WS) system has great potentials, many researchers' attention was attracted to this technique and active research was made. As a result, passenger cars equipped with 4WS systems were put on the market a few years ago. This report tries to identify the essential elements of the 4WS technology in terms of vehicle dynamics and control techniques. Based on the findings of this investigation, the report gives a mechanism of electronically controlling the steering system depending on the variable pressure applied on it. This enhances the controlling and smoothens the operation of steering mechanism.


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