The Kinematics of A-Pair Jointed Serial Linkages

Author(s):  
James D. Robinson ◽  
M. John D. Hayes

A new kinematic pair called an algebraic screw pair, or A-pair, is introduced that utilizes the self-motions inherent to a specific configuration of Griffis-Duffy platform. Using the A-pair as a joint in a hybrid parallel-serial kinematic chain results in a sinusoidal coupling of rotation and translation between adjacent links. This motion affects both the direct and inverse kinematics of such chains. Presented in this paper are the direct kinematics of chains using A-pairs and an algorithm for the inverse kinematics of a 4A-pair chain.

2011 ◽  
Vol 35 (4) ◽  
pp. 491-503 ◽  
Author(s):  
James D. Robinson ◽  
M. John D. Hayes

The algebraic screw pair, or A-pair, represents a new class of kinematic constraint that exploits the self-motions inherent to a specific configuration of Griffis-Duffy platform. Using the A-pair as a joint in a hybrid parallel-serial kinematic chain results in a sinusoidal coupling of rotation and translation between adjacent links. The resulting linkage is termed an A-chain. This paper reveals the dynamic equations of motion of a single A-pair and examines the impact of the inertial properties of the legs of the A-pair on the dynamics. A numerical example illustrates the impact of the leg effects from different perspectives and shows that while the gravity effects of the legs are significant, it may be possible to neglect the leg kinetic energy from the dynamics model.


1992 ◽  
Vol 114 (3) ◽  
pp. 406-413 ◽  
Author(s):  
V. Murthy ◽  
K. J. Waldron

The generalized lobster arm is a six revolute open kinematic chain with 3 consecutive intersecting pairs of axes. A new solution of the inverse position kinematics problem of this arm which takes advantage of its specific geometry is presented. A comparison is made with the direct position kinematics problem of the series-parallel dual mechanism. The equations governing the two problems show strong similarity and can each be reduced to a sixteenth degree univariate polynomial equation. The dual series-parallel mechanism is the one that exhibits, with the lobster arm, the symmetry that exists between the wrench and the velocity motor. Although the results presented here have intrinsic interest, a more generally important feature is the relationship between the solutions to the inverse kinematics of the serial mechanism and the direct kinematics of the parallel mechanism. Although the series-parallel duality has not been shown to hold in the position domain, except in terms of very general characteristics, it is shown here that the two solutions are of the same degree and have other features in common.


2006 ◽  
Vol 129 (3) ◽  
pp. 320-325 ◽  
Author(s):  
Farhad Tahmasebi

Closed-form direct and inverse kinematics of a new three-degree-of-freedom (DOF) parallel manipulator with inextensible limbs and base-mounted actuators are presented. The manipulator has higher resolution and precision than the existing three-DOF mechanisms with extensible limbs. Since all of the manipulator actuators are base mounted, higher payload capacity, smaller actuator sizes, and lower power dissipation can be obtained. The manipulator is suitable for alignment applications where only tip, tilt, and piston motions are significant. The direct kinematics of the manipulator is reduced to solving an eighth-degree polynomial in the square of the tangent of the half-angle between one of the limbs and the base plane. Hence, there are at most 16 assembly configurations for the manipulator. In addition, it is shown that the 16 solutions are eight pairs of reflected configurations with respect to the base plane. Numerical examples for the direct and inverse kinematics of the manipulator are also presented.


2019 ◽  
Vol 10 (1) ◽  
pp. 22
Author(s):  
Jiahong He ◽  
Weilun Xu ◽  
Bingtuan Gao

This paper proposes a self-insulating joint design based on the cable-driven parallel-series (CDPS) mechanism and electrical insulation analysis. The design provides the motions, mechanic support, and electrical insulation for robotic arms in live-line operation, which can maintain the equipment without manual intervention and power interruption. This CDPS mechanism can integrate four degrees of freedom (DOFs) motion in one joint, while the traditional series joint can only realize one DOF independently. The cable forces in the CDPS are calculated by the inverse kinematics to ensure the safe and flexible operation of the mechanism. The self-insulating joint has certain advantages over other designs because the electrical insulation is integrated into the joint instead of the traditional extra insulation layer. This integration reduces the weight of the arm mechanic structure. In addition, the structural complexity and weight are further reduced by separating the actuators and motors from the joint by using CDPS. Electric field distribution near the joint is calculated by the charge simulation method to analyze the insulation performance under the voltage of 35 kV. The cable forces and electric field distribution of the mechanism are measured to validate the simulation models. The inverse kinematics and insulation models of the self-insulating joint can provide detailed information for the mechanic and insulation design of the robotic arms.


2011 ◽  
Vol 58-60 ◽  
pp. 1902-1907 ◽  
Author(s):  
Xin Fen Ge ◽  
Jing Tao Jin

The intrinsically redundant series manipulator’s kinematics were studied by the exponential product formula of screw theory, the direct kinematics problem and Inverse kinematics problems were analyzed, and the intrinsically redundant series manipulator’s kinematics solution that based on exponential product formulas were proposed; the intrinsically redundant series manipulator’s kinematics is decomposed into several simple sub-problems, then analyzed sub-problem, and set an example to validate the correctness of the proposed method. Finally, comparing the exponential product formula and the D-H parameters, draw that they are essentially the same in solving the manipulator’s kinematics, so as to the algorithm of the manipulator’s kinematics based on exponential product formulas are correct, and the manipulator’s kinematics process based on exponential product formula is more simple and easier to real-time control of industrial.


Author(s):  
Farhad Tahmasebi

Closed-form direct and inverse kinematics of a new three degree-of-freedom (DOF) parallel manipulator with inextensible limbs and base-mounted actuators are presented. The manipulator has higher resolution and precision than the existing three DOF mechanisms with extensible limbs. Since all of the manipulator actuators are base-mounted; higher payload capacity, smaller actuator sizes, and lower power dissipation can be obtained. The manipulator is suitable for alignment applications where only tip, tilt, and piston motions are significant. The direct kinematics of the manipulator is reduced to solving an eighth-degree polynomial in the square of tangent of half-angle between one of the limbs and the base plane. Hence, there are at most sixteen assembly configurations for the manipulator. In addition, it is shown that the sixteen solutions are eight pairs of reflected configurations with respect to the base plane. Numerical examples for the direct and inverse kinematics of the manipulator are also presented.


2003 ◽  
Vol 13 (02) ◽  
pp. 119-127 ◽  
Author(s):  
Antonio Carlos Padoan ◽  
Guilherme de A. Barreto ◽  
Aluizio F. R. Araújo

In this paper we proposed an unsupervised neural architecture, called Temporal Parametrized Self Organizing Map (TEPSOM), capable of learning and reproducing complex robot trajectories and interpolating new states between the learned ones. The TEPSOM combines the Self-Organizing NARX (SONARX) network, responsible for coding the temporal associations of the robotic trajectory, with the Parametrized Self-Organizing (PSOM) network, responsible for an efficient interpolation mechanism acting on the SONARX neurons. The TEPSOM network is used to model the inverse kinematics of the PUMA 560 robot during the execution of trajectories with repeated states. Simulation results show that the TEPSOM is more accurate than the SONARX in the reproduction of the learned trajectories.


Author(s):  
M. Sailaja ◽  
R. D. V. Prasad

Nowadays the robot technology is advancing rapidly and the use of robots in industries has been increasing. In designing a robot manipulator, kinematicsplays a vital role. The kinematic problem of manipulator control is divided into two types, direct kinematics and inverse kinematics. Robot inverse kinematics, which is important in robot path planning, is a fundamental problem in robotic control. Past solutions for this problem have been through the use of various algebraic or algorithmic procedures, which may be less accurate and time consuming. Artificial neural networks have the ability to approximate highly non-linear functions applied in robot control. The neural network approach deserves examination because of the fundamental properties of computation speed, and they can generalize untrained solutions. In the present work an attempt has been made to evaluate the problemof robot inverse kinematics of Stanford manipulator using artificial neural network approach. Finally two programs are written using C language to solve inverse kinematic problem of Stanford manipulator using Back propagation method of artificial neural network. In this network, the input layer has six nodes, the hidden layer has three nodes, and the output layer has two nodes. And also Elbow manipulator was modelled and its direct kinematics was analysed.


2014 ◽  
Vol 697 ◽  
pp. 327-333
Author(s):  
Shi Yin Qiu ◽  
Rui Bo Yuan ◽  
Guan You Wang ◽  
Yong Da Ma ◽  
Zhen Ling Long ◽  
...  

A simple method for measuring and calculating the finger joint angular displacement was proposed to serve as the basis for designing dexterous hand and rehabilitation robot hand. The direct kinematics model and the inverse kinematics equation of the finger were established at the beginning of this paper. Then, the trajectory of the fingertip, from which the coordinates of the fingertip were extracted by using AutoCAD, was captured by camera. Finally, the trajectory coordinates of the fingertip were substituted into the inverse kinematics equations to solve the angular displacements of the proximal interphalangeal (PIP), distal interphalangeal (DIP) and metacarpophalangeal (MCP) joints. The calculating precision testing of the finger joint angular displacement needs to substitute the angular displacements calculated before into the direct kinematics equations of the finger to calculate the trajectory of the fingertip. Then, the average Euclidean distance between the calculated trajectory and the real trajectory was computed to test the calculating precision of the finger joint angular displacement. The average Euclidean distance of each fingers is less than 0.05mm, which proves the high calculating precision of the finger joint angular displacement and the efficiency of the method presented in this paper.


2012 ◽  
Vol 591-593 ◽  
pp. 1593-1598
Author(s):  
Jian Jun Li ◽  
Yan Ding Wei ◽  
Xiao Jun Zhou

A new structure of 6-RSPS simulator platform which can be rotated infinitely is presented. The solution of direct kinematics problem of parallel structure is the fundamental problem. For the solution of this problem, according to the links vector diagram, the relationship of the position and orientation of the platform between the length of links and the rotate angle of the under-hinge is derived. BP network is applied, then using the previous data obtained by inverse kinematics as the training data and testing data of BP network, get the direct kinematics solution. Simulation results verified that the solution of direct kinematics applied the BP network can be meet the requirements completely, and the error percentages are within the acceptable range.


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