Inverse kinematics of free-floating space robots with minimum dynamic disturbance

Robotica ◽  
1996 ◽  
Vol 14 (6) ◽  
pp. 667-675 ◽  
Author(s):  
Fengfeng Xi
Keyword(s):  
Inverse Kinematics ◽  
New Method ◽  
Space Robots ◽  
Simple Fact ◽  
Generalized Jacobian ◽  
Space Manipulator ◽  
End Effector ◽  
Dynamic Disturbance ◽  
Space Manipulators

In this paper a new method is presented for solving the inverse kinematics of free-floating space manipulators. The idea behind the method is to move the space manipulator along a path with minimum dynamic disturbance. The method is proposed to use the manipulator Jacobian instead of the generalized Jacobian of the spacecraft-manipulator system. This is based on the simple fact that, if the space manipulator moves along the so-called Zero Disturbance Path (ZDP), the spacecraft is immovable. As a result, the space manipulator can in this case be treated as a terrestrial fixed-based manipulator. Hence, the motion mapping between the joints and the end-effector can be described directly by the manipulator Jacobian. In the case that the ZDP does not exist, it can be shown that the solutions obtained by the proposed method provide a path with minimum dynamic disturbance.

A new method to solve robot inverse kinematics using Assur virtual chains

Robotica ◽  
2009 ◽  
Vol 27 (7) ◽  
pp. 1017-1026 ◽  
Author(s):  
H. Simas ◽  
R. Guenther ◽  
D. F. M. da Cruz ◽  
D. Martins
Keyword(s):  
Exponential Stability ◽  
Numerical Integration ◽  
Numerical Algorithm ◽  
Inverse Kinematics ◽  
Integration Method ◽  
Parallel Robots ◽  
New Method ◽  
Numerical Integration Method ◽  
End Effector ◽  
Novel Method

SUMMARYThis paper describes a numerical algorithm to solve the inverse kinematics of parallel robots based on numerical integration. Inverse kinematics algorithms based on numerical integration involve the drift phenomena of the solution; as a consequence, errors are generated when the end-effector location differs from that desired. The proposed algorithm associates a novel method to describe the differential kinematics with a simple numerical integration method. The methodology is presented in this paper and its exponential stability is proved. A numerical example and a real application are presented to outline its advantages.

On the Inverse Kinematics of Space Manipulators for Avoiding Dynamic Singularities

1997 ◽  
Vol 119 (2) ◽  
pp. 340-346 ◽  
Author(s):  
F. Xi ◽  
R. G. Fenton
Keyword(s):  
Conventional Method ◽  
Inverse Kinematics ◽  
Convergence Rates ◽  
Generalized Jacobian ◽  
Space Manipulators

A spacecraft-manipulator system is considered in this paper. Dynamic singularities are the singularities occurring when inverting the system generalized Jacobian required by the conventional method for solving the inverse kinematics of space manipulators. To avoid dynamic singularities, three methods are developed here based on the manipulator Jacobian, instead of the system generalized Jacobian. These methods are compared with the conventional method on the basis of their convergence rates, accuracies and sensitivities. Results of this comparison are presented in this paper.

scholarly journals GA Based Adaptive Singularity-Robust Path Planning of Space Robot for On-Orbit Detection

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Jianwei Wu ◽  
Deer Bin ◽  
Xiaobing Feng ◽  
Zhongpu Wen ◽  
Yin Zhang
Keyword(s):  
Path Planning ◽  
Space Robot ◽  
Damping Factor ◽  
Tracking Accuracy ◽  
Generalized Jacobian ◽  
Space Manipulator ◽  
End Effector ◽  
Space Environments ◽  
Damped Least Squares ◽  
Value Decomposition

As a new on-orbit detection platform, the space robot could ensure stable and reliable operation of spacecraft in complex space environments. The tracking accuracy of the space manipulator end-effector is crucial to the detection precision. In this paper, the Cartesian path planning method of velocity level inverse kinematics based on generalized Jacobian matrix (GJM) is proposed. The GJM will come across singularity issue in path planning, which leads to the infinite or incalculable joint velocity. To solve this issue, firstly, the singular value decomposition (SVD) is used for exposition of the singularity avoidance principle of the damped least squares (DLS) method. After that, the DLS method is improved by introducing an adaptive damping factor which changes with the singularity. Finally, in order to improve the tracking accuracy of the singularity-robust algorithm, the objective function is established, and two adaptive parameters are optimized by genetic algorithm (GA). The simulation of a 6-DOF free-floating space robot is carried out, and the results show that, compared with DLS method, the proposed method could improve the tracking accuracy of space manipulator end-effector.

Dynamic Singularities in Free-Floating Space Manipulators

1993 ◽  
Vol 115 (1) ◽  
pp. 44-52 ◽  
Author(s):  
E. Papadopoulos ◽  
S. Dubowsky
Keyword(s):  
Attitude Control ◽  
Dynamic Properties ◽  
Kinematic Structure ◽  
Attitude Control System ◽  
Space Manipulator ◽  
End Effector ◽  
Planning And Control ◽  
Space Manipulators ◽  
Fixed Base ◽  
And Control

Dynamic Singularities are shown for free-floating space manipulator systems where the spacecraft moves in response to manipulator motions without compensation from its attitude control system. At a dynamic singularity the manipulator is unable to move its end-effector in some inertial direction; thus dynamic singularities must be considered in the design, planning, and control of free-floating space manipulator systems. The existence and location of dynamic singularities cannot be predicted solely from the manipulator kinematic structure because they are functions of the dynamic properties of the system, unlike the singularities for fixed-base manipulators. Also analyzed are the implications of dynamic singularities to the nature of the system’s workspace.

scholarly journals Omnidirectional Analysis of Spatial Manipulator

2015 ◽  
Vol 2015 ◽  
pp. 1-11
Author(s):  
Yuquan Leng ◽  
Yang Zhang ◽  
Xu He ◽  
Wei Zhang ◽  
Haitao Luo ◽  
...  
Keyword(s):  
Theoretical Approach ◽  
Sphere Surface ◽  
Space Manipulator ◽  
End Effector ◽  
Space Manipulators ◽  
Test Platform ◽  
Utilization Ratio

Space manipulators are mainly used in the spatial loading task. According to problems of the spatial loading diversity, the testing loading installing position, and the utilization ratio of a test platform, the space manipulator is asked to evaluate the position and attitude of itself. This paper proposes the Point Omnidirectional Coefficient (POC) with unit attitude sphere/circle to describe attitude of the end-effector, which evaluates any points in the attainable space of the manipulators, in combination with the manipulation’s position message, and get relationships between its position and attitude of all points in the attainable space. It represents the mapping between sphere surface and plane for mission attitude constraints and the method for calculating volume of points space including attainable space, Omnidirectional space, and mission attitude space. Furthermore, the Manipulator Omnidirectional Coefficient based on mission or not is proposed for evaluating manipulator performance. Through analysis and simulation about 3D and 2D manipulators, the results show that the above theoretical approach is feasible and the relationships about link lengths, joints angles, attainable space, and Manipulator Omnidirectional Coefficient are drawn for guiding design.

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.

Parametric Design of a Spherical Eight-Bar Linkage Based on a Spherical Parallel Manipulator

2008 ◽  
Vol 1 (1) ◽  
Author(s):  
Gim Song Soh ◽  
J. Michael McCarthy
Keyword(s):  
Inverse Kinematics ◽  
Parallel Manipulator ◽  
Parametric Design ◽  
Degree Of Freedom ◽  
Kinematics Analysis ◽  
End Effector ◽  
Arbitrary Base ◽  
Three Degree Of Freedom ◽  
Spherical Parallel Manipulator

This paper presents a procedure that determines the dimensions of two constraining links to be added to a three degree-of-freedom spherical parallel manipulator so that it becomes a one degree-of-freedom spherical (8, 10) eight-bar linkage that guides its end-effector through five task poses. The dimensions of the spherical parallel manipulator are unconstrained, which provides the freedom to specify arbitrary base attachment points as well as the opportunity to shape the overall movement of the linkage. Inverse kinematics analysis of the spherical parallel manipulator provides a set of relative poses between all of the links, which are used to formulate the synthesis equations for spherical RR chains connecting any two of these links. The analysis of the resulting spherical eight-bar linkage verifies the movement of the system.

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