A Geometrical Approach to the Inverse Kinematics of 6R Serial Robots With Offset Wrists

2015 ◽  
Author(s):  
Cuong Trinh ◽  
Dimiter Zlatanov ◽  
Matteo Zoppi ◽  
Rezia Molfino
Keyword(s):  
Inverse Kinematics ◽  
Joint Angle ◽  
Geometric Analysis ◽  
Geometrical Approach ◽  
Analysis Method ◽  
End Effector ◽  
Serial Robots ◽  
Spherical Wrist ◽  
Numerical Solver ◽  
Trigonometric Equations

The computation of the joint-angle values of a 6R serial manipulator for a given end-effector pose is more difficult for architectures lacking the conventional spherical wrist. Despite this added complexity, such arms have increasingly gained acceptance as they provide better dexterity for a number of tasks. The paper presents a geometric-analysis method for the inverse kinematics of a robot with an offset wrist. The sought postures are shown to correspond to the roots of four separate univariate trigonometric equations for the sixth joint angle. A standard numerical solver is applied to derive all sets of possible real solutions. By back-substitution, all the remaining angular variables are found in succession. Two particular arm designs are considered and full sets of solutions are obtained by the discussed approach. The method is easy to implement and can be applied to various 6R serial robots.

Joint angle variations analyses of the two link planar manipulator in welding by using inverse kinematics

Robotica ◽  
2005 ◽  
Vol 24 (3) ◽  
pp. 355-363 ◽  
Author(s):  
S. Bulut ◽  
M. B. Terzioǧlu
Keyword(s):  
Angular Velocity ◽  
Data Collection ◽  
Inverse Kinematics ◽  
Joint Angle ◽  
Joint Angles ◽  
End Effector ◽  
Fortran 90

In this paper, the joint angles of a two link planar manipulator are calculated by using inverse kinematics equations together with some geometric equalities. For a given position of the end-effector the joint angle and angular velocity of the links are derived. The analyses contains many equations which have to be solved. However, the solutions are rather cumbersome and complicated, therefore a program is written in Fortran 90 in order to do, the whole calculation and data collection. The results are given at the end of this paper.

Design and Analysis of a Biomimetic Wire-Driven Robot Arm

2011 ◽  
Author(s):  
Zheng Li ◽  
Ruxu Du ◽  
Man Cheong Lei ◽  
Song Mei Yuan
Keyword(s):  
Inverse Kinematics ◽  
Geometric Analysis ◽  
Forward Kinematics ◽  
Positioning Error ◽  
Robot Arm ◽  
End Effector ◽  
Fixed Node

Inspired by the octopus and snakes, we designed and built a wire-driven serpentine robot arm. The robot arm is made of a number of rigid nodes connected by two sets of wires. The rigid nodes act as the backbone while the wires work as the muscle, which enables the 2 DOF bending. The forward kinematics is derived using D-H method, while the inverse kinematics and its workspace can be solved by geometric analysis. To validate the design, a prototype is built. It is found that the positioning error of the robot arm is generally less than 2%. The advantage of this robot arm is that with several nodes fixed the rest nodes are still controllable. The positioning error is smaller when the fixed node is closer to the end effector.

GEOMETRIC APPROACH TO SOLVING THE INVERSE DISPLACEMENT PROBLEM OF CALIBRATED DECOUPLED 6R SERIAL ROBOTS

2014 ◽  
Vol 38 (1) ◽  
pp. 31-44 ◽  
Author(s):  
Albert Nubiola ◽  
Ilian A. Bonev
Keyword(s):  
Inverse Kinematics ◽  
Computation Time ◽  
Geometric Approach ◽  
End Effector ◽  
Forward Displacement ◽  
Displacement Problem ◽  
Robot Controller ◽  
Serial Robots ◽  
Level 3 ◽  
Direct Kinematics

This paper presents a simple but efficient way to numerically calculate the inverse displacement problem of calibrated decoupled 6R serial robots. The method is iterative and works with any type of calibrated robot model, such as level-3 models, since it requires no algebraic computation and no resolution of high-order polynomials, only the computation of the forward displacement problem of the calibrated robot model and the inverse kinematics of the nominal robot model. The method proposed can find up to eight possible solutions for a given end-effector pose. A numerical example is presented, with one million arbitrary end-effector poses of a level-3 calibrated ABB IRB 120 robot. The computation time for solving the inverse problem is analyzed, and in most cases is found to be only four times the time needed to calculate the nominal inverse kinematics and the calibrated direct kinematics. Furthermore, the method is fast enough to be implemented directly into the robot controller using the RAPID programming language.

A novel inverse kinematics method for 6-DOF robots with non-spherical wrist

2021 ◽  
Vol 157 ◽  
pp. 104180
Author(s):  
Jing Li ◽  
Hong Yu ◽  
NanYan Shen ◽  
Zhen Zhong ◽  
YiHao Lu ◽  
...  
Keyword(s):  
Inverse Kinematics ◽  
Spherical Wrist

Studies on Isotropy of Planar 5-Bar Linkages

2004 ◽  
Author(s):  
C. Amarnath ◽  
K. N. Umesh
Keyword(s):  
Geometric Approach ◽  
Geometrical Approach ◽  
End Effector ◽  
Isotropic Point ◽  
Important Requirement ◽  
Point To Point

The ability to move at reasonable ease in all directions is an important requirement in the design of manipulators. The degree of ease of mobility varies from point to point in the workspace of the manipulator’s end effector. Maximum ease of mobility is obtained at an isotropic point, and the minimum occurs at singularities. An attempt has been made here to use a geometric approach for determining the isotropic points in the workspace of planar 5-bar linkages. The geometrical approach leads to interesting observations on the location of isotropic points in the workspace. The procedure also yields a technique for the synthesis of 5-bar linkages and associated coupler points exhibiting isotropic behaviour. Additionally it has been shown that coupler points exhibiting isotropic mobility occur in pairs.

Inverse Kinematics of a 7-DOF Spraying Robot with 4R 3-DOF Non-spherical Wrist

2021 ◽  
Vol 101 (4) ◽  
Author(s):  
Yangyang Wang ◽  
Chen Zhao ◽  
Xuhao Wang ◽  
Peilun Zhang ◽  
Pan Li ◽  
...  
Keyword(s):  
Inverse Kinematics ◽  
Spherical Wrist

scholarly journals Finite-Horizon Kinetic Energy Optimization of a Redundant Space Manipulator

2021 ◽  
Vol 11 (5) ◽  
pp. 2346
Author(s):  
Alessandro Tringali ◽  
Silvio Cocuzza
Keyword(s):  
Kinetic Energy ◽  
Real Time ◽  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Computational Time ◽  
Redundant Manipulators ◽  
Space Robotics ◽  
Optimal Method ◽  
End Effector ◽  
Global Optimal

The minimization of energy consumption is of the utmost importance in space robotics. For redundant manipulators tracking a desired end-effector trajectory, most of the proposed solutions are based on locally optimal inverse kinematics methods. On the one hand, these methods are suitable for real-time implementation; nevertheless, on the other hand, they often provide solutions quite far from the globally optimal one and, moreover, are prone to singularities. In this paper, a novel inverse kinematics method for redundant manipulators is presented, which overcomes the above mentioned issues and is suitable for real-time implementation. The proposed method is based on the optimization of the kinetic energy integral on a limited subset of future end-effector path points, making the manipulator joints to move in the direction of minimum kinetic energy. The proposed method is tested by simulation of a three degrees of freedom (DOF) planar manipulator in a number of test cases, and its performance is compared to the classical pseudoinverse solution and to a global optimal method. The proposed method outperforms the pseudoinverse-based one and proves to be able to avoid singularities. Furthermore, it provides a solution very close to the global optimal one with a much lower computational time, which is compatible for real-time implementation.

A Hybrid Self-Stressed Cable-Driven Mechanism

2008 ◽  
Author(s):  
Saeed Behzadipour
Keyword(s):  
Static Loading ◽  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Tensile Force ◽  
Cable System ◽  
End Effector ◽  
Stiffness Analysis ◽  
Cable Length ◽  
Cable Drive ◽  
Forward And Inverse Kinematics

A new hybrid cable-driven manipulator is introduced. The manipulator is composed of a Cartesian mechanism to provide three translational degrees of freedom and a cable system to drive the mechanism. The end-effector is driven by three rotational motors through the cables. The cable drive system in this mechanism is self-stressed meaning that the pre-tension of the cables which keep them taut is provided internally. In other words, no redundant actuator or external force is required to maintain the tensile force in the cables. This simplifies the operation of the mechanism by reducing the number of actuators and also avoids their continuous static loading. It also eliminates the redundant work of the actuators which is usually present in cable-driven mechanisms. Forward and inverse kinematics problems are solved and shown to have explicit solutions. Static and stiffness analysis are also performed. The effects of the cable’s compliance on the stiffness of the mechanism is modeled and presented by a characteristic cable length. The characteristic cable length is calculated and analyzed in representative locations of the workspace.

Kinematics of a Fully-Decoupled Remote Center-of-Motion Parallel Manipulator for Minimally Invasive Surgery

2012 ◽  
Vol 6 (2) ◽  
Author(s):  
Chin-Hsing Kuo ◽  
Jian S. Dai
Keyword(s):  
Minimally Invasive Surgery ◽  
Minimally Invasive ◽  
Invasive Surgery ◽  
Inverse Kinematics ◽  
Parallel Manipulator ◽  
Degrees Of Freedom ◽  
Surgical Instruments ◽  
End Effector ◽  
Minimally Invasive Surgical ◽  
Inverse Kinematics Problem

A crucial design challenge in minimally invasive surgical (MIS) robots is the provision of a fully decoupled four degrees-of-freedom (4-DOF) remote center-of-motion (RCM) for surgical instruments. In this paper, we present a new parallel manipulator that can generate a 4-DOF RCM over its end-effector and these four DOFs are fully decoupled, i.e., each of them can be independently controlled by one corresponding actuated joint. First, we revisit the remote center-of-motion for MIS robots and introduce a projective displacement representation for coping with this special kinematics. Next, we present the proposed new parallel manipulator structure and study its geometry and motion decouplebility. Accordingly, we solve the inverse kinematics problem by taking the advantage of motion decouplebility. Then, via the screw system approach, we carry out the Jacobian analysis for the manipulator, by which the singular configurations are identified. Finally, we analyze the reachable and collision-free workspaces of the proposed manipulator and conclude the feasibility of this manipulator for the application in minimally invasive surgery.

Force Capabilities of Two-Degree-of-Freedom Serial Robots Equipped With Passive Isotropic Force Limiters

2015 ◽  
Author(s):  
Meiying Zhang ◽  
Thierry Laliberté ◽  
Clément Gosselin
Keyword(s):  
Human Robot Interaction ◽  
Contact Forces ◽  
Degree Of Freedom ◽  
Practical Implementation ◽  
Robot Interaction ◽  
End Effector ◽  
Serial Robots ◽  
Serial Robot ◽  
Maximum Contact ◽  
Two Degree Of Freedom

This paper proposes the use of passive force and torque limiting devices to bound the maximum forces that can be applied at the end-effector or along the links of a robot, thereby ensuring the safety of human-robot interaction. Planar isotropic force limiting modules are proposed and used to analyze the force capabilities of a two-degree-of-freedom planar serial robot. The force capabilities at the end-effector are first analyzed. It is shown that, using isotropic force limiting modules, the performance to safety index remains excellent for all configurations of the robot. The maximum contact forces along the links of the robot are then analyzed. Force and torque limiters are distributed along the structure of the robot in order to ensure that the forces applied at any point of contact along the links are bounded. A power analysis is then presented in order to support the results. Finally, examples of mechanical designs of force/torque limiters are shown to illustrate a possible practical implementation of the concept.

Sign in / Sign up

Export Citation Format

Share Document