scholarly journals Modal Kinematic Analysis of a Parallel Kinematic Robot with Low-Stiffness Transmissions

Robotics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 132
Author(s):  
Paolo Righettini ◽  
Roberto Strada ◽  
Filippo Cortinovis
Keyword(s):  
High Speed ◽  
Parallel Robots ◽  
Maximum Speed ◽  
Kinematic Structure ◽  
End Effector ◽  
New Approach ◽  
Working Space ◽  
Modes Of Vibration ◽  
Parallel Kinematic ◽  
Actuated Joints

Several industrial robotic applications that require high speed or high stiffness-to-inertia ratios use parallel kinematic robots. In the cases where the critical point of the application is the speed, the compliance of the main mechanical transmissions placed between the actuators and the parallel kinematic structure can be significantly higher than that of the parallel kinematic structure itself. This paper deals with this kind of system, where the overall performance depends on the maximum speed and on the dynamic behavior. Our research proposes a new approach for the investigation of the modes of vibration of the end-effector placed on the robot structure for a system where the transmission’s compliance is not negligible in relation to the flexibility of the parallel kinematic structure. The approach considers the kinematic and dynamic coupling due to the parallel kinematic structure, the system’s mass distribution and the transmission’s stiffness. In the literature, several papers deal with the dynamic vibration analysis of parallel robots. Some of these also consider the transmissions between the motors and the actuated joints. However, these works mainly deal with the modal analysis of the robot’s mechanical structure or the displacement analysis of the transmission’s effects on the positioning error of the end-effector. The discussion of the proposed approach takes into consideration a linear delta robot. The results show that the system’s natural frequencies and the directions of the end-effector’s modal displacements strongly depend on its position in the working space.

A Novel Perspective in the Design of Cable-Driven Systems

2008 ◽  
Author(s):  
Giulio Rosati ◽  
Damiano Zanotto
Keyword(s):  
Systems Design ◽  
The Novel ◽  
End Effector ◽  
New Approach ◽  
Driven Systems ◽  
Working Space ◽  
Novel Approach ◽  
Workspace Analysis ◽  
Workspace Optimization ◽  
Novel Design

This paper deals with a novel approach to the design of cable-driven systems. This kind of robots possesses several desirable features that distinguish them from common manipulators, such as: low-inertia, cost-effectiveness, safety, easy reconfiguration and transportability. One key-issue that arises from the unilateral actuation is the design for workspace optimization. Most previous researches on cable-driven systems design focused their attention on workspace analysis for existing devices. Conversely, we introduce a new approach for improving workspace by design, introducing movable pulley-blocks rather than increasing the number of cables. By properly moving the pulley-blocks, the end-effector can be always maintained in the best part of the working space, thus enhancing robot capabilities without the need for additional cables. Furthermore, the eventuality of cable interference is strongly reduced. In this paper, the novel design concept is applied to different planar point-mass cable-driven robots, with one or more translating pulley-blocks. The maximum feasible isotropic force, along with the power dissipation and the effective mass at the end-effector are employed to compare the performances of different configurations.

DeltaBot: A New Cable-Based Ultra High Speed Robot

2003 ◽  
Author(s):  
Saeed Behzadipour ◽  
Robert Dekker ◽  
Amir Khajepour ◽  
Edmon Chan
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Manufacturing Industry ◽  
Design Procedure ◽  
Parallel Manipulators ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Manufacturing Cost ◽  
End Effector ◽  
Serial Manipulators

The growing needs for high speed positioning devices in the automated manufacturing industry have been challenged by robotic science for more than two decades. Parallel manipulators have been widely used for this purpose due to their advantage of lower moving inertia over the conventional serial manipulators. Cable actuated parallel robots were introduced in 1980’s to reduce the moving inertia even further. In this work, a new cable-based parallel robot is introduced. For this robot, the cables are used not only to actuate the end-effector but also to apply the necessary kinematic constraints to provide three pure translational degrees of freedom. In order to maintain tension in the cables, a passive air cylinder is used to push the end-effector against the stationary platform. In addition to low moving inertia, the new design benefits from simplicity and low manufacturing cost by eliminating joints from the robot’s mechanism. The design procedure and the results of experiments will be discussed in the following.

Dynamic balancing of hexapods for high-speed applications

Robotica ◽  
1999 ◽  
Vol 17 (3) ◽  
pp. 335-342 ◽  
Author(s):  
F. Xi
Keyword(s):  
Parallel Mechanism ◽  
High Speed ◽  
Dominant Factor ◽  
Kinematic Structure ◽  
Dynamic Balancing ◽  
End Effector ◽  
Tool Holder

In this paper, a method is proposed for dynamic balancing of hexapods for high-speed applications. The kinematic structure of the hexapod is based on the parallel mechanism. For high-speed applications, hexapod dynamics is the dominant factor, and dynamic balancing becomes very important. The proposed method is aimed at minimizing the changes in the hexapod inertia over the workspace by utilizing the tool holder attached to the hexapod's end-effector as a counterweight.

Direct Pose Measurement: A Suitable Way to Increase the Accuracy of Parallel Robots?

2007 ◽  
Author(s):  
Christian Munzinger ◽  
Martin Kipfmu¨ller
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Parallel Robots ◽  
Dynamic Parameters ◽  
Parallel Mechanisms ◽  
End Effector ◽  
Parallel Kinematic Machines ◽  
Machine Tool Structures ◽  
Conventional Machine ◽  
Parallel Kinematic

Parallel robots are showing a high potential for the application in machine tools requesting high stiffness and dynamics. Nevertheless, a broad use of parallel mechanisms in machine tools is nowadays avoided by the minor accuracy of parallel kinematic machines compared to conventional machine tool structures, which entails the need for complex calibration algorithms. In this paper, a strategy to avoid the calibration of parallel kinematic machines by rearranging the measurement system to the end effector is presented. Because this rearrangement entails a massive modification of the machine tools control circuit that causes stability problems, first tests of the concept have been carried out via simulation. The focus of these tests was to determine the necessary dynamic parameters of a suitable machine tool’s structure. The results of these tests are used to derive guidelines for the design of a machine tool with direct pose measurement. Finally, a design approach for a suitable machine tool is presented.

Workspace and Singularity Characteristics of 3-DOF Planar Parallel Robots

2009 ◽  
Author(s):  
Ming Huang
Keyword(s):  
Computer Simulations ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Geometric Parameters ◽  
Kinematic Structure ◽  
Link Length ◽  
End Effector ◽  
Serial Chain ◽  
Parametric Studies ◽  
Position And Orientation

A study of workspace and singularity characteristics is presented for two common types of 3-DOF planar parallel robot manipulators. The robots considered feature a kinematic structure with 3 in-parallel actuated, R-R-R and R-P-R serial chain geometries. In this study, computer simulations aided with graphic visualization were used to characterize the complete pose workspace (for ranges of both position and orientation) and the singularity inherent to the systems. Parametric studies have also been performed to ascertain the way in which both characteristics vary with respect to various geometric parameters such as pivot location, link length, and platform size for end-effector. Results are shown by way of a unique composite ratio of the available workspace to the density of singularity within that workspace.

scholarly journals Technology-Oriented Optimization of the Secondary Design Parameters of Robots for High-Speed Machining Applications

2010 ◽  
Author(s):  
Se´bastien Briot ◽  
Anatol Pashkevich ◽  
Damien Chablat
Keyword(s):  
Machine Tools ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Parallel Robots ◽  
Design Parameters ◽  
Speed Up ◽  
Parallel Kinematic ◽  
Parallel Kinematic Machine Tools ◽  
Accuracy Constraints ◽  
Three Degrees Of Freedom

In this paper, a new methodology for the optimal design of the secondary geometric parameters (shape of links, size of the platform, etc.) of parallel kinematic machine tools is proposed. This approach aims at minimizing the total mass of the robot under position accuracy constraints. This methodology is applied to two translational parallel robots with three degrees-of-freedom (DOF): the Y-STAR and the UraneSX. The proposed approach is able to speed up the design process and to help the designer to find more quickly a set of design parameters.

scholarly journals Theoretical Positioning Accuracy for Serial and Parallel Kinematic Structure

2014 ◽  
Vol 14 (5) ◽  
pp. 243-251 ◽  
Author(s):  
Eva Kurekova ◽  
Martin Halaj ◽  
Milada Omachelová ◽  
Ilja Martišovitš
Keyword(s):  
Design Phase ◽  
Plasma Cutting ◽  
Kinematic Structure ◽  
Specific Design ◽  
Positioning Accuracy ◽  
End Effector ◽  
Machine Performance ◽  
Cutting Head ◽  
Parallel Kinematic ◽  
Measurement Uncertainties

Abstract Modern production machines employ complex kinematic structures that shall enhance their performance. As those machines are very sophisticated electro-mechanical structures, their design is time consuming and financially demanding. Therefore, designers search for new possibilities how to estimate future properties of the machine as early as in the design phase. The paper gives a brief introduction to the adoption of methodology of measurement uncertainties into the design of production machines. The adapted methodology enables to estimate the theoretical positioning accuracy of the machine end effector that is one of the important indicators of machine performance. Both serial and parallel kinematic structures are considered in the paper. Methodology and sample calculations of theoretical positioning accuracy are presented for serial kinematic structure (represented by advanced plasma cutting head) and parallel kinematic structure, represented by one specific design named Tricept.

High-speed running performance: a new approach to assessment and prediction

2003 ◽  
Vol 95 (5) ◽  
pp. 1955-1962 ◽  
Author(s):  
Matthew W. Bundle ◽  
Reed W. Hoyt ◽  
Peter G. Weyand
Keyword(s):  
Oxygen Uptake ◽  
Performance Assessment ◽  
High Speed ◽  
Aerobic Power ◽  
Anaerobic Power ◽  
Maximum Speed ◽  
Treadmill Test ◽  
New Approach ◽  
Running Performance ◽  
Trained Runners

We hypothesized that allout running speeds for efforts lasting from a few seconds to several minutes could be accurately predicted from two measurements: the maximum respective speeds supported by the anaerobic and aerobic powers of the runner. To evaluate our hypothesis, we recruited seven competitive runners of different event specialties and tested them during treadmill and overground running on level surfaces. The maximum speed supported by anaerobic power was determined from the fastest speed that subjects could attain for a burst of eight steps (∼3 s or less). The maximum speed supported by aerobic power, or the velocity at maximal oxygen uptake, was determined from a progressive, discontinuous treadmill test to failure. All-out running speeds for trials of 3-240 s were measured during 10-13 constant-speed treadmill runs to failure and 4 track runs at specified distances. Measured values of the maximum speeds supported by anaerobic and aerobic power, in conjunction with an exponential constant, allowed us to predict the speeds of all-out treadmill trials to within an average of 2.5% ( R2 = 0.94; n = 84) and track trials to within 3.4% ( R2 = 0.86; n = 28). An algorithm using this exponent and only two of the all-out treadmill runs to predict the remaining treadmill trials was nearly as accurate (average = 3.7%; R2 = 0.93; n = 77). We conclude that our technique 1) provides accurate predictions of high-speed running performance in trained runners and 2) offers a performance assessment alternative to existing tests of anaerobic power and capacity.

scholarly journals Wrench-Feasible Workspace of Mobile Cable-Driven Parallel Robots

2020 ◽  
Vol 12 (3) ◽  
Author(s):  
Tahir Rasheed ◽  
Philip Long ◽  
Stéphane Caro
Keyword(s):  
Convex Hull ◽  
Case Studies ◽  
High Speed ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Static Equilibrium ◽  
Equilibrium Conditions ◽  
Cable Tension ◽  
End Effector ◽  
Novel Concept

Abstract Cable-driven parallel robots (CDPRs) hold numerous advantages over conventional parallel robots in terms of high speed and large workspace. Cable-driven parallel robots whose workspace can be further increased by the modification of their geometric architecture are known as reconfigurable cable-driven parallel robots. A novel concept of reconfigurable cable-driven parallel robots that consists of a classical cable-driven parallel robot mounted on multiple mobile bases is known as mobile CDPR. This paper proposes a methodology to trace the wrench-feasible workspace of mobile cable-driven parallel robots by determining its available wrench set. Contrary to classical cable-driven parallel robots, we show that the available wrench set of a mobile cable-driven parallel robot depends, not only on the cable tension limits but also on the static equilibrium conditions of the mobile bases. The available wrench set is constructed by two different approaches known as convex hull approach and hyperplane shifting method. Three case studies are carried out for the validation of the proposed methodology. The proposed approach is experimentally validated on a mobile cable-driven parallel robot with a point-mass end-effector and two mobile bases.

Teleoperation Hybrid Robot for Cell Micro and Nano Manipulations

2006 ◽  
Author(s):  
Florin Ionescu ◽  
Ilie Talpasanu
Keyword(s):  
Control System ◽  
High Speed ◽  
Robot Control ◽  
Three Dimensional ◽  
Haptic Interface ◽  
Kinematic Structure ◽  
Regional Structure ◽  
Working Space ◽  
Rotational Joint ◽  
And Control

In this paper is presented a developed robotic system for cell micro/nano manipulation and penetration, based on the visual/haptic interface. The operator’s motion and manipulations skills are transferred to the robot control system by direct teleoperation. The robot’s regional structure has three translational joints and one passive rotational joint for the nanorobot adjustment. The three-d.o.f piezo actuated nano robot is a compact and stiff structure, to guarantee the three-dimensional nano motion and control for sample manipulation or injection. The closed kinematic structure with two fundamental loops has been chosen for the required working space, high speed, and precision. The digraph-matroid approach is used for the model’s kinematics, and the SDS software for the robot’s simulation.

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