Kinematic analysis and self-calibration of three-legged modular parallel robots

1999 ◽  
Author(s):  
Wee K. Lim ◽  
Guilin Yang ◽  
I-Ming Chen ◽  
Song H. Yeo
2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Sven Lilge ◽  
Kathrin Nuelle ◽  
Georg Boettcher ◽  
Svenja Spindeldreier ◽  
Jessica Burgner-Kahrs

Abstract The use of continuous and flexible structures instead of rigid links and discrete joints is a growing field of robotics research. Recent work focuses on the inclusion of continuous segments in parallel robots to benefit from their structural advantages, such as a high dexterity and compliance. While some applications and designs of these novel parallel continuum robots have been presented, the field remains largely unexplored. Furthermore, an exact quantification of the kinematic advantages and disadvantages when using continuous structures in parallel robots is yet to be performed. In this paper, planar parallel robot designs using tendon actuated continuum robots instead of rigid links and discrete joints are proposed. Using the well-known 3-RRR manipulator as a reference design, two parallel continuum robots are derived. Inverse and differential kinematics of these designs are modeled using constant curvature assumptions, which can be adapted for other actuation mechanisms than tendons. Their kinematic performances are compared to the conventional parallel robot counterpart. On the basis of this comparison, the advantages and disadvantages of using continuous structures in parallel robots are quantified and analyzed. Results show that parallel continuum robots can be kinematic equivalent and exhibit similar kinematic performances in comparison to conventional parallel robots depending on the chosen design.


Author(s):  
Philipp Last ◽  
Annika Raatz ◽  
Ju¨rgen Hesselbach ◽  
Nenad Pavlovic ◽  
Ralf Keimer

Model based geometric calibration is well known to be an efficient way to enhance absolute accuracy of robotic systems. Generally its application requires redundant measurements, which are achieved by external metrology equipment in most traditional calibration techniques. However, these methods are usually time-consuming, expensive and inconvenient. Thus, so-called self-calibration methods have achieved attention from researchers, which either use internal sensors or rely on mechanical constraints instead. In this paper a new self-calibration technique is presented for parallel robots which is motivated by the idea of constrained calibration. The new approach utilizes a special machine component called the adaptronic swivel joint in order to achieve the required redundant information. Compared to similar approaches it offers several advantages. The new calibration scheme is described and verified in simulation studies using a RRRRR-structure as an example.


Author(s):  
Muhammed R. Pac ◽  
Dan O. Popa

Legged robots are more maneuverable, and can negotiate rough terrain much better than conventional locomotion using wheels. However, since the kinematic or dynamic analysis of such robots involves closed chains, it is typically more difficult to investigate the impact of design changes, such as the number, or the design of its legs, to robot performance. Most legged robots consist of 4 legs (quadrupeds) or 6 legs (hexapods). This paper discusses the kinematic analysis of an unconventional, symmetrical 5-legged robot with 2-DOF (Degrees Of Freedom) universal joints in each leg. The analysis was carried out in order to predict the mobility of the upper body platform, and investigate the number of robot actuators needed for mobility. The product of exponentials formulation with respect to the local coordinate frames is used to describe the twists of the joints. The analysis is based on the idea that the robot body platform along with the legs can be considered instantaneously as a parallel robot manipulating the ground. Hence, the analysis can be done using the Jacobian formulation of parallel robots. Simulation results confirm the mobility analysis that the robot can have at most 3-DOF for the body and that these freedoms are coupled rotations and translations in 3D space also with a dependence on the configuration of the robot.


Robotica ◽  
1992 ◽  
Vol 10 (1) ◽  
pp. 35-44 ◽  
Author(s):  
Y. Amirat ◽  
F. Artigue ◽  
J. Pontnau

SummaryThis paper presents at first a static and kinematic analysis of closed chains mechanisms which permits to deduce different possible fully parallel architectures. Then we focus on a particular parallel architecture with C5 links designed to perform precise assembly tasks. A general modeling of this C5 parallel robot is presented. Two typical assembly tasks in the automotive industry are also proposed; the first one uses the C5 links parallel robot as a left-hand device, while the second one uses it as the terminal tool of a sequential manipulator.


Author(s):  
Salua Hamaza ◽  
Patrice Lambert ◽  
Marco Carricato ◽  
Just Herder

This paper explores the fundamentals of parallel robots with configurable platforms (PRCP), as well as the design and the kinematic analysis of those. The concept behind PRCP is that the rigid (non-configurable) end-effector is replaced by a closed-loop chain, the configurable platform. The use of a closed-loop chain allows the robot to interact with the environment from multiple contact points on the platform, which reflects the presence of multiple end-effectors. This results in a robot that successfully combines motion and grasping capabilities into a structure that provides an inherent high stiffness. This paper aims to introduce the QuadroG robot, a 4 degrees of freedom PRCP which finely merges planar motion together with grasping capabilities.


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