DELTA: a simple and efficient parallel robot

Robotica ◽  
1990 ◽  
Vol 8 (2) ◽  
pp. 105-109 ◽  
Author(s):  
F. Pierrot ◽  
C. Reynaud ◽  
A. Fournier
Keyword(s):  
Inverse Kinematics ◽  
Research Team ◽  
Dynamic Models ◽  
Inverse Dynamics ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Kinematic Parameters ◽  
Mechanical Structure ◽  
Serial Robots ◽  
École Polytechnique

SummaryThe DELTA parallel robot, designed by an EPFL (Ecole Polytechnique Fédérale de Lausanne) research team, is a mechanical structure which has the advantage of parallel robots and ease of serial robots modeling. This paper presents solutions for a complete modeling of the DELTA parallel robot (direct and inverse kinematics, inverse statics, inverse dynamics), with few arithmetic and trigonometric operations. Our method is based on a satisfactory choice of kinematic parameters and on a few restricting hypotheses for the static and dynamic models. We give some details of each model, we present some computation results and we put the emphasis on some particular points, showing the capabilities of this mechanical structure.

A New Design of a 6-DOF Parallel Robot

1990 ◽  
Vol 2 (4) ◽  
pp. 308-315 ◽  
Author(s):  
François Pierrot ◽  
◽  
Masaru Uchiyama ◽  
Pierre Dauchez ◽  
Alain Fournier ◽  
...  
Keyword(s):  
Inverse Kinematics ◽  
Dynamic Capabilities ◽  
Inverse Dynamics ◽  
Parallel Robot ◽  
Degree Of Freedom ◽  
Mechanical Structure ◽  
Delta Robot ◽  
Good Set ◽  
Six Degree Of Freedom ◽  
Three Degree Of Freedom

This paper presents a six-degree-of-freedom parallel robot which has been recently designed. The design is based on a three-degree-of-freedom parallel robot called DELTA which was designed in Switzerland by EPFL. First, we give equations corresponding to different models of the DELTA robot: forward and inverse kinematics as well as inverse dynamics. An important feature of our method in deriving these models is to use a “good” set of parameters in order to simplify the equations. Then, in an attempt to extend the principle of the DELTA robot mechanical structure to a six-degree-offreedom parallel robot, we propose a new design called HEXA. Equations for kinematics and dynamics of the HEXA robot are presented and show that it has the same dynamic capabilities as the DELTA robot because, like the DELTA robot, it can be built with light-weight materials and easily modeled. Finally, we discuss optimization of the HEXA robot mechanical structure.

DESIGN OF A POSITION AND FORCE CONTROL SCHEME FOR 6RSS PARALLEL ROBOTS AND ITS APPLICATION IN CHEWING ROBOTS

2010 ◽  
Vol 07 (03) ◽  
pp. 477-489 ◽  
Author(s):  
L. HUANG ◽  
W. L. XU ◽  
J. TORRANCE ◽  
J. E. BRONLUND
Keyword(s):  
Force Control ◽  
Dynamic Models ◽  
Controller Design ◽  
Impedance Control ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Work Requirements ◽  
Serial Robots ◽  
Control Scheme

Parallel robots have been found in many applications where the work requirements are beyond the capabilities of serial robots. For example, mouth movements of chewing foods can be generated by a parallel robot. In this paper, the issue of dynamic position and force control of a chewing robot with a 6RSS mechanism is addressed. The kinematic and dynamic models of a generic 6RSS robot are developed and are then simplified considering the special features of a practical chewing robot and the requirements of controller design. An impedance control scheme is proposed to achieve the position and force control of the robot. A detailed description on the steps to implement the controller is also presented.

Application of the Design For Control Approach for the Integrated Design and Control of Parallel Robots

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Qing Li
Keyword(s):  
Dynamic Models ◽  
Integrated Design ◽  
Parallel Robot ◽  
Parallel Robots ◽  
System Stability ◽  
Control Approach ◽  
Mechanical Structure ◽  
Iterative Computation ◽  
Design For Control ◽  
And Control

To effectively control a complex mechanical structure for precise performance, a model-based type of controller is usually desired. In cases of controlling parallel robots, however, the iterative computation due to the complexity of the dynamic models can result in difficulties in controller implementations and system stability analysis. To avoid this problem, simplified dynamic models can be obtained through approximation, nevertheless, performance accuracy will suffer due to simplification. This paper suggests applying the effective Design For Control (DFC) approach to handle this problem. The underlying idea of the DFC approach is that, no matter how complex a system is, as long as its mechanical structure can be judiciously designed such that it results in a simple dynamic model, a simple control algorithm may be good enough for a satisfactory control performance. Through out the discussion in the paper, the integrated design and control of a two DOF parallel robot is studied as an illustration example. Experimental validation has demonstrated the effectiveness of the DFC approach.

On Force and Motion Control of Serial-Parallel Robots

1996 ◽  
Author(s):  
Shih-Liang Wang
Keyword(s):  
Control Algorithm ◽  
Virtual Work ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Joint Torque ◽  
Compact Structure ◽  
Serial Robots ◽  
S Matrix ◽  
Serial Robot ◽  
Rate Control Algorithm

Abstract A serial-parallel robot has the high stiffness and accuracy of a parallel robot, and a large workspace and compact structure of a serial robot. In this paper, the resolved force control algorithm is derived for serial-parallel robots, including a 3-articulated-arm platform robot, a linkage robot, and two cooperating serial robots. A S matrix is derived to relate joint torque to the external load. Using the principle of virtual work, S is used in resolved rate control algorithm to relate the tool velocity to joint rate. S can be easily expanded to the control of redundant actuation, and it can be used to interpret singularity. MATLAB is used to verify these control algorithms with graphical motion animation.

Experimental validation on the integrated design and control of a parallel robot

Robotica ◽  
2005 ◽  
Vol 24 (2) ◽  
pp. 173-181 ◽  
Author(s):  
Qing Li
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Dynamic Models ◽  
Integrated Design ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Approximation Techniques ◽  
Control Approach ◽  
Modeling Errors ◽  
And Control

Due to the demands from the robotic industry, robot structures have evolved from serial to parallel. The control of parallel robots for high performance and high speed tasks has always been a challenge to control engineers. Following traditional control engineering approaches, it is possible to design advanced algorithms for parallel robot control. These approaches, however, may encounter problems such as heavy computational load and modeling errors, to name it a few. To avoid heavy computation, simplified dynamic models can be obtained by applying approximation techniques, nevertheless, performance accuracy will suffer due to modeling errors. This paper suggests applying an integrated design and control approach, i.e., the Design For Control (DFC) approach, to handle this problem. The underlying idea of the DFC approach can be illustrated as follows: Intuitively, a simple control algorithm can control a structure with a simple dynamic model quite well. Therefore, no matter how sophisticate a desired motion task is, if the mechanical structure is designed such that it results in a simple dynamic model, then, to design a controller for this system will not be a difficult issue. As such, complicated control design can be avoided, on-line computation load can be reduced and better control performance can be achieved. Through out the discussion in the paper, a 2 DOF parallel robot is redesigned based on the DFC concept in order to obtain a simpler dynamic model based on a mass-balancing method. Then a simple PD controller can drive the robot to achieve accurate point-to-point tracking tasks. Theoretical analysis has proven that the simple PD control can guarantee a stable system. Experimental results have successfully demonstrated the effectiveness of this integrated design and control approach.

Optimizing the Torque Distribution of a Redundantly Actuated Parallel Robot to Study the Temporomandibular Reaction Forces During Food Chewing

2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Naser Mostashiri ◽  
Jaspreet Dhupia ◽  
Alexander Verl ◽  
John Bronlund ◽  
Weiliang Xu
Keyword(s):  
Inverse Dynamics ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Cost Functions ◽  
Measurement Tool ◽  
Redundancy Resolution ◽  
Theoretical Formulation ◽  
Temporomandibular Joints ◽  
Redundantly Actuated

Abstract Inverse dynamics solution of redundantly actuated parallel robots (RAPRs) requires redundancy resolution methods. In this paper, the Lagrange’s equations of the second kind are used to derive governing equations of a chewing RAPR. Jacobian analysis of the RAPR is presented. As redundancy resolutions, two different optimization cost functions corresponding to specific neuromuscular objectives, which are minimization of effort of the muscles of mastication and temporomandibular joints (TMJs) loads, are used to find the RAPR’s optimized actuation torque distributions. The actuation torques under the influence of experimentally determined dynamic chewing forces on molar teeth reproduced from a separate chewing experiment are calculated for realistic in vitro simulation of typical human chewing. These actuation torques are applied to the RAPR with a distributed-computed-torque proportional-derivative control scheme, allowing the RAPR’s mandible to follow a human subject’s chewing trajectory. TMJs loads are measured by force sensors, which are comparable with the computed loads from theoretical formulation. The TMJs loads for the two optimization cost functions are measured while the RAPR is chewing 3 g of peanuts on its left molars. Maximum and mean of the recorded loads on the left TMJ were higher in both cases. Moreover, the maximum and mean of the recorded loads on both TMJs were smaller for the cost function minimizing the TMJs loads. These results demonstrate validity of the model, suggesting the RAPR as a potential TMJ loads measurement tool to study the chewing characteristics of patients suffering from pain in TMJs.

Modeling of Dynamics and Model-Based Control of DELTA Direct-Drive Parallel Robot

1995 ◽  
Vol 7 (4) ◽  
pp. 344-352 ◽  
Author(s):  
Karol Miller ◽  
◽  
Boris S. Stevens ◽  
◽  
Keyword(s):  
Trajectory Tracking ◽  
Inverse Dynamics ◽  
Slight Modification ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Direct Application ◽  
Hamilton’S Principle ◽  
Direct Drive ◽  
Hamilton's Principle ◽  
Extended Space

The term ""Extended Space"" used in this article is hereby defined as a union of the operational and articulation spaces of a manipulator. The advantages in the use of such coordinates (extended space) in the description of DELTA robot is presented here and discussed in some detail. The emerging importance of parallel robots has necessitated an increased sophistication to achieve improved control. A method based on the direct application of the Hamilton's Principle in extended space, has been applied efficiently to solving the inverse problem of dynamics and implemented for real time application in the control law of the direct-drive version of DELTA parallel robot.1-3) The full dynamic model of this robot has been developed herein. The numerical efficiency and other benefits of this approach over the more classical Lagrange and Newton-Euler methods for the inverse dynamics problem solving are also briefly discussed. For similar models, the version obtained by the direct application of Hamilton's principle is found to possess 23% less mathematical operations than for the Lagrangebased model. Frictional effects. being very small in the direct-drive manipulator, are not included in the present Hamilton development but can be handled with a slight modification. Furthermore the acceleration information of the robot are not required as input states to the Hamilton model. The measurement of trajectory tracking performances for different controllers is conducted. The repeatability of the robot trajectory tracking is determined. The improvement obtained in the control algorithm's performance after the Hamilton implementation is proven to be conclusive.

Position Analysis for a Class of Novel 3-DOF Translational Parallel Robot Mechanisms

2001 ◽  
Author(s):  
Qiong Jin ◽  
Ting-Li Yang
Keyword(s):  
Path Planning ◽  
Inverse Kinematics ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Position Analysis ◽  
Dimensional Parameters ◽  
Forward And Inverse Kinematics ◽  
Topological Characteristics ◽  
Kinematic Joint

Abstract A class of new 3-DOF parallel robot mechanisms is investigated. Closed-formed solutions are developed for both the forward and inverse kinematics. Compared with known 3-DOF parallel robot mechanisms, these mechanisms are not only simple in structure with fewer solutions for position analyses but also decoupled. The mechanism decouplity, which is related to the topological characteristics, dimensional parameters, kinematic joint types and the choice of input-joints, is very useful for real control and path planning of parallel robots.

scholarly journals ARE PARALLEL ROBOTS MORE ACCURATE THAN SERIAL ROBOTS?

2007 ◽  
Vol 31 (4) ◽  
pp. 445-455 ◽  
Author(s):  
Sébastien Briot ◽  
Ilian A. Bonev
Keyword(s):  
Parallel Robot ◽  
Parallel Robots ◽  
Kinematic Accuracy ◽  
Serial Robots ◽  
Meaningful Comparison ◽  
Planar Robots

It is widely claimed that parallel robots are intrinsically more accurate than serial robots because their errors are averaged instead of added cumulatively, an assertion which has not been properly addressed in the literature. This paper addresses this void by comparing the kinematic accuracy of two pairs of serial-parallel 2-DOF planar robots. Only input errors are considered and all robots are optimized for accuracy, the only constraint being that they cover a given desired workspace. The results of this comparison seem to confirm that parallel robots are less sensitive to input errors than serial robots. However, this comparison is too limited to draw any general conclusions. Besides, it is virtually impossible to make a meaningful comparison between other pairs of serial and parallel robot. Therefore, there is no simple answer to this question of superiority.

scholarly journals Geometric Parameter Calibration for a Cable-Driven Parallel Robot Based on a Single One-Dimensional Laser Distance Sensor Measurement and Experimental Modeling

Sensors ◽  
2018 ◽  
Vol 18 (7) ◽  
pp. 2392 ◽  
Author(s):  
XueJun Jin ◽  
Jinwoo Jung ◽  
Seong Ko ◽  
Eunpyo Choi ◽  
Jong-Oh Park ◽  
...  
Keyword(s):  
Position Control ◽  
Uncertainty Modeling ◽  
Parallel Robot ◽  
Parallel Robots ◽  
The Body ◽  
Robot Kinematics ◽  
Kinematic Parameters ◽  
Body Frame ◽  
Geometric Uncertainty ◽  
Calibration Methods

A cable-driven parallel robot has benefits of wide workspace, high payload, and high dynamic response owing to its light cable actuator utilization. For wide workspace applications, in particular, the body frame becomes large to cover the wide workspace that causes robot kinematic errors resulting from geometric uncertainty. However, appropriate sensors as well as inexpensive and easy calibration methods to measure the actual robot kinematic parameters are not currently available. Hence, we present a calibration sensor device and an auto-calibration methodology for the over-constrained cable-driven parallel robots using one-dimension laser distance sensors attached to the robot end-effector, to overcome the robot geometric uncertainty and to implement precise robot control. A novel calibration workflow with five phases—preparation, modeling, measuring, identification, and adjustment—is proposed. The proposed calibration algorithms cover the cable-driven parallel robot kinematics, as well as uncertainty modeling such as cable elongation and pulley kinematics. We performed extensive simulations and experiments to verify the performance of the suggested method using the MINI cable robot. The experimental results show that the kinematic parameters can be identified correctly with 0.92 mm accuracy, and the robot position control accuracy is increased by 58%. Finally, we verified that the developed calibration sensor devices and the calibration methodology are applicable to the massive-size cable-driven parallel robot system.

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