Clearance-Induced Position Uncertainty of Planar Linkages and Parallel Manipulators

2017 ◽  
Author(s):  
Kwun-Lon Ting ◽  
Kuan-Lun Hsu
Keyword(s):  
Kinematic Model ◽  
Parallel Manipulators ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Position Uncertainty ◽  
Joint Clearances ◽  
Planar Linkages ◽  
Oscillation Characteristics ◽  
Linkage Model ◽  
Input Error

The paper presents a simple and effective kinematic model and methodology, based on Ting’s N-bar rotatability laws [2629], to assess the extent of the position uncertainty caused by joint clearances for any linkage and manipulators connected with revolute or prismatic pairs. The model is derived and explained with geometric rigor based on Ting’s rotatability laws. The significant contribution includes (1) the clearance link model for P-joint that catches the translation and oscillation characteristics of the slider within the clearance and separates the geometric effect of clearance from the input error, (2) a simple uncertainty linkage model that features a deterministic instantaneous structure mounted on non-deterministic flexible legs, (3) the generality of the method, which is effective for multiloop linkages and parallel manipulators. The discussion is carried out through symmetrically constructed planar eight-bar parallel robots. It is found that the uncertainty region of a three-leg parallel robot is enclosed by a hexagon, while that of its serial counterpart is enclosed by a circle inscribed by the hexagon. A numerical example is also presented. The finding and proof, though only based on three-leg planar 8-bar parallel robots, may have a wider implication suggesting that based on kinematics, parallel robots tends to inherit more position uncertainty than their serial counterparts. The use of more loops in parallel robots cannot fully offset the adverse effect on position uncertainty caused by the use of more joints.

Clearance-Induced Position Uncertainty of Planar Linkages and Parallel Manipulators

2017 ◽  
Vol 9 (6) ◽  
Author(s):  
Kwun-Lon Ting ◽  
Kuan-Lun Hsu ◽  
Jun Wang
Keyword(s):  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Target Position ◽  
Parallel Manipulators ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Joint Clearance ◽  
Position Uncertainty ◽  
Kinematic Effect ◽  
Joint Clearances

The paper presents a simple and effective kinematic model and methodology to assess and evaluate the extent of the position uncertainty caused by joint clearances for multiple-loop linkage and manipulators connected with revolute or prismatic pairs. The model is derived and explained with geometric rigor based on Ting's rotatability laws. The significant contributions include (1) the clearance link model for a P-joint that catches the translation and oscillation characteristics of the slider within the clearance and separates the geometric effect of clearances from the input error, (2) the generality of the method, which is effective for multiloop linkages and parallel manipulators, and (3) settling the dispute on the position uncertainty effect to parallel and serial robots due to joint clearance. The discussion is illustrated and carried out through symmetrically configured planar 8 bar parallel robots. It is found that at a target position, the uncertainty region of a three degrees-of-freedom (DOF) three-leg parallel robot is enclosed by a hexagon with curve edges, while that of its serial counterpart is enclosed by a circle included in the hexagon. A numerical example is presented. The finding and proof, though only based on three-leg planar 8 bar parallel robots, may have a wider implication suggesting that based on the kinematic effect of joint clearance, parallel robots tends to inherit more position uncertainty than their serial counterparts. The use of more loops in not only parallel robots but also single-DOF linkages cannot fully offset the adverse effect on position uncertainty caused by the use of more joints.

Rotatability of the Floating Link on Multi-Loop Planar Linkages

2020 ◽  
Vol 12 (6) ◽  
Author(s):  
Cody Leeheng Chan ◽  
Kwun-Lon Ting
Keyword(s):  
Rotation Angle ◽  
Parallel Manipulators ◽  
Orientation Error ◽  
Joint Rotation ◽  
Position Uncertainty ◽  
End Effector ◽  
Uncertainty Model ◽  
Branch Formation ◽  
Joint Clearances ◽  
Planar Linkages

Abstract This paper proposes a method to deal with the orientation uncertainty problem affected by joint clearances. To solve this problem, it is necessary to establish the theory of mobility of the floating link of multi-loop linkages. Since the theory of the mobility of floating link is yet complete, this paper provides a simple treatment to determine the rotatability between any two links, adjoined or not, in planar multi-loop linkages. The rotation angle of the floating link with respect to the reference link is defined so that there is no ambiguity in analyzing the rotation range of the floating link. Based on the joint rotation space (JRS) method, one may identify not only the branch formation but also the rotatability between any two links on each of the branches. It is a visualized method that reveals the rotation characteristic of multi-loop linkages. This paper demonstrates the rotation range of the floating link with respect to the reference link on six-bar Stephenson linkages, 2-degree-of-freedom (DOF). 7-bar linkages, and 3-DOF. Eight-bar parallel manipulators. This might be the first paper to deal with the rotatability of 3-DOF planar multi-loop linkages. This paper uses the method to predict the clearance-induced angle uncertainty of the 8-bar parallel manipulators, which determines the worst orientation error of the end-effector and fills up the void of the joint clearance uncertainty model proposed by Ting et al. (2017, “Clearance-Induced Position Uncertainty of Planar Linkages and Parallel Manipulators,” J. Mech. Rob., 9, p. 061001).

scholarly journals Control of a 3-RRR Planar Parallel Robot Using Fractional Order PID Controller

2020 ◽  
Vol 17 (6) ◽  
pp. 822-836
Author(s):  
Auday Al-Mayyahi ◽  
Ammar A. Aldair ◽  
Chris Chatwin
Keyword(s):  
Fractional Order ◽  
Material Handling ◽  
State Of The Art ◽  
Kinematic Model ◽  
Parallel Robot ◽  
Inverse Kinematic ◽  
Open Loop ◽  
Parallel Robots ◽  
The State ◽  
Revolute Joints

Abstract3-RRR planar parallel robots are utilized for solving precise material-handling problems in industrial automation applications. Thus, robust and stable control is required to deliver high accuracy in comparison to the state of the art. The operation of the mechanism is achieved based on three revolute (3-RRR) joints which are geometrically designed using an open-loop spatial robotic platform. The inverse kinematic model of the system is derived and analyzed by using the geometric structure with three revolute joints. The main variables in our design are the platform base positions, the geometry of the joint angles, and links of the 3-RRR planar parallel robot. These variables are calculated based on Cayley-Menger determinants and bilateration to determine the final position of the platform when moving and placing objects. Additionally, a proposed fractional order proportional integral derivative (FOPID) is optimized using the bat optimization algorithm to control the path tracking of the center of the 3-RRR planar parallel robot. The design is compared with the state of the art and simulated using the Matlab environment to validate the effectiveness of the proposed controller. Furthermore, real-time implementation has been tested to prove that the design performance is practical.

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.

Kinematic uncertainty analysis of a cable-driven parallel robot based on an error transfer model

2021 ◽  
pp. 1-23
Author(s):  
Jun Gao ◽  
Bin Zhou ◽  
Bin Zi ◽  
Sen Qian ◽  
Ping Zhao
Keyword(s):  
Uncertainty Analysis ◽  
Kinematic Model ◽  
Evidence Theory ◽  
Parallel Robot ◽  
Fast Response ◽  
Inverse Kinematic ◽  
Parallel Robots ◽  
Transfer Model ◽  
The Given ◽  
Error Transfer

Abstract Cable-driven parallel robots (CDPRs) are a kind of mechanism with large workspace, fast response, and low inertia. However, due to the existence of fixed pulleys, it is unavoidable to bring uncertain cable lengths and lead to pose errors of the end-effector (EE). The inverse kinematic model of a CDPR for picking up medicines is established by considering radii of fixed pulleys. The influence of radii of fixed pulleys on errors of cable lengths is explored. Error transfer model of the CPDR is constructed, and uncertain sources of cable lengths are analyzed. Based on evidence theory and error transfer model, an evidence theory-based uncertainty analysis method (ETUAM) is presented. The structural performance function for kinematic response is derived based on error transfer model. Belief and plausibility measures of joint focal elements under the given threshold are obtained. Kinematic error simulations show that errors of cable lengths become larger with the increase of radii of fixed pulleys. Compared with the vertex method and Monte Carlo method, numerical examples demonstrate the accuracy and efficiency of the ETUAM when it comes to the kinematic uncertainty analysis of the CDPR.

scholarly journals Modeling Parallel Robot Kinematics for 3T2R and 3T3R Tasks Using Reciprocal Sets of Euler Angles

Robotics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 68 ◽  
Author(s):  
Moritz Schappler ◽  
Svenja Tappe ◽  
Tobias Ortmaier
Keyword(s):  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Robot Kinematics ◽  
Euler Angles ◽  
Gradient Descent Algorithm ◽  
Kinematic Models ◽  
Rotational Degrees Of Freedom ◽  
Definition Of

Industrial manipulators and parallel robots are often used for tasks, such as drilling or milling, that require three translational, but only two rotational degrees of freedom (“3T2R”). While kinematic models for specific mechanisms for these tasks exist, a general kinematic model for parallel robots is still missing. This paper presents the definition of the rotational component of kinematic constraints equations for parallel robots based on two reciprocal sets of Euler angles for the end-effector orientation and the orientation residual. The method allows completely removing the redundant coordinate in 3T2R tasks and to solve the inverse kinematics for general serial and parallel robots with the gradient descent algorithm. The functional redundancy of robots with full mobility is exploited using nullspace projection.

Types Synthesis of Redundant Actuation Parallel Robot

2011 ◽  
Vol 219-220 ◽  
pp. 953-956
Author(s):  
Jin Liang Gong ◽  
Yan Fei Zhang ◽  
Xiu Ting Wei
Keyword(s):  
Parallel Manipulators ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Redundant Actuation ◽  
View Point ◽  
Output Link ◽  
Practical Applications ◽  
Plücker Coordinates ◽  
Theoretical View ◽  
Kinematic Joint

Redundant parallel robots have been under increasing developments from a theoretical view point as well as for practical applications. Compared with the traditional parallel manipulators, they have such merits of more load, faster speed and higher accuracy. The method about how to build up redundant actuation parallel robot is introduced. Considering that the kinematic joint and limb are basic elements to constitute a proper parallel robot mechanism, special Plücker coordinates is adopted to describe the displacements of the output link of a limb or the robot mechanism. Then the principle for design of the redundant actuation parallel robot mechanisms is presented and example of the 2RRR&2PP parallel robot mechanism is brought forth and analyzed by this method.

Kinematic Isotropic Configuration of Spatial Cable-Driven Parallel Robots

2011 ◽  
Vol 1 (4) ◽  
pp. 61-86
Author(s):  
Hamoon Hadian ◽  
Abbas Fattah
Keyword(s):  
Parallel Manipulators ◽  
Parallel Robot ◽  
Numerical Approach ◽  
Parallel Robots ◽  
Degree Of Freedom ◽  
Tension Index ◽  
Symbolic Method ◽  
Three Degree Of Freedom ◽  
Cable Robots

In this paper, the authors study the kinematic isotropic configuration of spatial cable-driven parallel robots by means of four different methods, namely, (i) symbolic method, (ii) geometric workspace, (iii) numerical workspace and global tension index (GTI), and (iv) numerical approach. The authors apply the mentioned techniques to two types of spatial cable-driven parallel manipulators to obtain their isotropic postures. These are a 6-6 cable-suspended parallel robot and a novel restricted three-degree-of-freedom cable-driven parallel robot. Eventually, the results of isotropic conditions of both cable robots are compared to show their applications.

Actuation-Coordinated Mobile Parallel Robots With Hybrid Mobile and Manipulation Function

2021 ◽  
Author(s):  
Dongming Gan ◽  
Jiaming Fu ◽  
Mo Rastgaar ◽  
Byung-Cheol Min ◽  
Richard Voyles
Keyword(s):  
Parallel Mechanism ◽  
Inverse Dynamics ◽  
Parallel Manipulators ◽  
Extreme Environment ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Mobile Manipulators ◽  
Large Area ◽  
Base Size ◽  
Inverse Dynamics Analysis

Abstract Mobile robots with manipulation capability are a key technology that enables flexible robotic interactions, large area covering and remote exploration. This paper presents a novel class of actuation-coordinated mobile parallel robots (ACMPRs) that utilize parallel mechanism configurations and perform hybrid moving and manipulation functions through coordinated wheel actuators. The ACMPRs differ with existing mobile manipulators by their unique combination of the mobile wheel actuators and the parallel mechanism topology through prismatic joint connections. The common motion of the wheels will provide the mobile function while their differentiation will actuate the parallel manipulator function. This new concept reduces the actuation requirement and increases the manipulation accuracy and mobile motion stability through the coordinated and connected wheel actuators comparing with existing mobile parallel manipulators. The relative wheel location on the base frame also enables a reconfigurable base size with variable moving stability on the ground. The basic concept and general type synthesis are introduced and followed by the kinematics and inverse dynamics analysis of a selected three limb ACMPR. A numerical simulation also illustrates the dynamics model and the motion property of the new mobile parallel robot. The work provides a basis for introducing this new class of robots for potential applications in surveillance, industrial automation, construction, transportation, human assistance, medical applications and other operations in extreme environment such as nuclear plants, Mars, etc.

Kinematic Isotropic Configuration of Spatial Cable-Driven Parallel Robots

2013 ◽  
pp. 266-290
Author(s):  
Hamoon Hadian ◽  
Abbas Fattah
Keyword(s):  
Parallel Manipulators ◽  
Parallel Robot ◽  
Numerical Approach ◽  
Parallel Robots ◽  
Degree Of Freedom ◽  
Tension Index ◽  
Symbolic Method ◽  
Three Degree Of Freedom ◽  
Cable Robots

In this paper, the authors study the kinematic isotropic configuration of spatial cable-driven parallel robots by means of four different methods, namely, (i) symbolic method, (ii) geometric workspace, (iii) numerical workspace and global tension index (GTI), and (iv) numerical approach. The authors apply the mentioned techniques to two types of spatial cable-driven parallel manipulators to obtain their isotropic postures. These are a 6-6 cable-suspended parallel robot and a novel restricted three-degree-of-freedom cable-driven parallel robot. Eventually, the results of isotropic conditions of both cable robots are compared to show their applications.

Sign in / Sign up

Export Citation Format

Share Document