Switching method to avoid algorithmic singularity in vision-based control of a space robot
27 Jul 2015-pp 271-276
TL;DR: This paper presents a novel approach for algorithmic singularity avoidance for reactionless visual servoing of a satellite mounted space robot, and presents a geometric interpretation of its occurrence, and proposes a method to avoid it.
Abstract: This paper presents a novel approach for algorithmic singularity avoidance for reactionless visual servoing of a satellite mounted space robot. Task priority approach is used to perform visual servoing while reactionless manipulation of the space robot. Algorithmic singularity is prominent in such cases of prioritizing two tasks. The algorithmic singularity is different from the kinematic and dynamic singularities as the former is an artefact of the tasks at hand, and difficult to predict. In this paper, we present a geometric interpretation of its occurrence, and propose a method to avoid it. The method involves path planning in image space, and generates a sequence of images that guides the robot towards goal avoiding algorithmic singularity. The method is illustrated through numerical studies on a 6-DOF planar dual-arm robot mounted on a service satellite.
Citations
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01 Oct 2016
TL;DR: The proposed algorithm is able to incorporate the necessary coupling between the motions of the the dual arms and the base of the robot to ensure zero base reactions and gives the flexibility to apply multiple constraints in both the image space and the configuration space.
Abstract: This work addresses path planning for reactionless visual servoing of a redundant dual-arm space robot through exploration in the image space. The planner explores the image moment based feature space, impends acceleration to the image features and extends the feature tree. A reactionless visual servoing control law is integrated to extend the tree in the configuration space simultaneously. The proposed algorithm is able to incorporate the necessary coupling between the motions of the the dual arms and the base of the robot to ensure zero base reactions. Additionally, it also gives the flexibility to apply multiple constraints in both the image space and the configuration space. The effectiveness of the proposed framework is exhibited by implementing the algorithm on a numerical model of a 14-DoF dual arm space robot.
8 citations
01 Oct 2016
TL;DR: In this article, a multi-input multi-output (MIMO) direct adaptive torque controller is presented that uses a conventional fuzzy system to provide asymptotic end-effector tracking of a reference path for a 9-DOF hyper-redundant manipulator.
Abstract: In this paper, multi-input multi-output (MIMO) direct adaptive torque controller is presented that uses a conventional fuzzy system to provide asymptotic end-effector tracking of a reference path for a 9-DOF hyper-redundant manipulator. It is illustrated via simulations that the MIMO adaptive controller, which drives the torque of each joint to control end-effector dynamic variables, can highly improve the robotic performance considering both its kinematics and dynamics while executing motion control or tracking a reference in work space. Also, it increases the robustness with respect to disturbances, sensor noise and poorly understood dynamics. The efficacy of our control algorithm affects the accuracy, stability and robustness of both motion control and path tracking.
7 citations
01 Sep 2016
TL;DR: It is illustrated via simulations that the MIMO adaptive controller, which drives the torque of each joint to control end-effector dynamic variables, can highly improve the robotic performance considering both its kinematics and dynamics while executing motion control or tracking a reference in work space.
Abstract: In this paper, a multi-input multi-output (MIMO) direct adaptive torque controller is presented that uses a conventional fuzzy system to provide asymptotic end-effector tracking of a reference path for a 7-DOF redundant robotic arm. In order to find a control strategy that is both robust and efficient with respect to disturbances, sensor noise and poorly understood dynamics, we compare this controller with two other dynamic controllers: single-input, single-output (SISO) PID controller and multi-input, multi-output (MIMO) feedback linearization controller. It is illustrated via simulations that the MIMO adaptive controller, which drives the torque of each joint to control end-effector dynamic variables, can highly improve the robotic performance considering both its kinematics and dynamics while executing motion control or tracking a reference in work space. The efficacy of our control algorithm affects the accuracy, stability and robustness of both motion control and path tracking.
2 citations
Cites methods from "Switching method to avoid algorithm..."
...Such singularity problem is strictly a function of the choice of parameterization and its avoidance has been studied by different methods as [9]–[11]....
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TL;DR: In this article, a general control framework for the constrained control of multibody systems actuated by vectorized thrusters is presented, where a cascade control scheme augmented with a constraint enforcement unit is proposed to stabilize the system while ensuring constraint satisfaction at all times.
1 citations
01 Jul 2016
TL;DR: In this paper, a MIMO direct adaptive torque controller is presented that uses a conventional fuzzy system with ∊-modification to provide the end-effector tracking of a reference path for a 9DOF hyper-redundant manipulator.
Abstract: In this paper, multi-input multi-output (MIMO) direct adaptive torque controller is presented that uses a conventional fuzzy system with ∊-modification to provide the end-effector tracking of a reference path for a 9-DOF hyper-redundant manipulator. Also, an on-line task modification method (OTMM) is applied to achieve singularity avoidance for the hyper-redundant arm at the velocity level. It is illustrated via simulations that ∊-modification provides an on-line estimation of the unknown system dynamics boundaries for adaptive control and the OTMM avoids the singularity on-line and waives offline singularity avoidance path planning and the effort to check whether the singularity is escapable for the hyper-redundant manipulator.
Cites methods from "Switching method to avoid algorithm..."
...Such singularity problem is strictly a function of the choice of parameterization and its avoidance has been studied by different methods as [9], [10], [11]....
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References
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01 Jun 1997
TL;DR: A new task-priority redundancy resolution technique is developed that overcomes the effects of algorithmic singularities and is applied to a seven-degree-of-freedom manipulator in numerical case studies to demonstrate its effectiveness.
Abstract: Practical application of the task-priority redundancy resolution technique must deal with the occurrence of kinematic and algorithmic singularities. The aim of this paper is twofold. First, the application of existing singularity-robust methods to the case of kinematically redundant arms is studied. Then, a new task-priority redundancy resolution technique is developed that overcomes the effects of algorithmic singularities. Computational aspects of the solutions are also considered in view of real-time implementation of a kinematic control algorithm. The method is applied to a seven-degree-of-freedom manipulator in numerical case studies to demonstrate its effectiveness.
647 citations
"Switching method to avoid algorithm..." refers background or methods in this paper
...The solution of (1) and (2) is obtained using task priority framework [15] as...
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...Given the prominence of algorithmic singularity [15], this section presents its geometric interpretation, which was lacking in the previous literature, for the sack of better understanding of the problem at hand....
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...The proposed work builds on [14] and the limitations of the work done [15]....
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...The methods shown in [15], [16], [17] helped in taking care of the algorithmic singularity, however, at the cost of compromise on the secondary task....
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...Throughout this phase, a singularity measure is tracked, which is defined as [15]...
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21 May 2001
TL;DR: The existence of the ZRM is very limited for a 6 DOF manipulator arm mounted on a free-flying base, but it is discussed how more operational freedom is obtained with a kinematically redundant arm.
Abstract: Presents the experimental results and post-flight analysis of reaction null-space based reactionless manipulation, or zero reaction maneuver (ZRM). The concept has been developed with an insight into the motion dynamics of free-flying multibody systems and its practical availability is clearly demonstrated with ETS-VII, a Japanese space robot. The ZRM is proven particularly useful for removing the velocity limit of manipulation due to the reaction constraint and the time loss due to waiting for the attitude recovery. The existence of the ZRM is very limited for a 6 DOF manipulator arm mounted on a free-flying base, but it is discussed how more operational freedom is obtained with a kinematically redundant arm.
154 citations
TL;DR: The use of humans to service satellites designed for servicing has been adequately demonstrated, but it appears that on-orbit servicing will not be heavily used, and, as a result, is not likely to be economically viable.
Abstract: The use of humans to service satellites designed for servicing has been adequately demonstrated on the Hubble Space Telescope and International Space Station. Currently, robotic on-orbit servicing technology is maturing with risk reduction programs such asOrbital Express. Robotic servicing appears to be technically feasible and provides a set of capabilities which range from satellite inspection to physical upgrade of components. However, given the current design and operation paradigms of satellite architectures, it appears that on-orbit servicing will not be heavily used, and, as a result, is not likely to be economically viable. To achieve the vision of on-orbit servicing, the development of a newvalue proposition for satellite architectures is necessary. This new value proposition is oriented around rapid response to technological or market change and design of satellites with less redundancy.
125 citations
"Switching method to avoid algorithm..." refers background in this paper
...I. INTRODUCTION On Orbit Services (OSS) [1], such as orbital detritus management, refurbishment and refuelling of orbiting satellites, construction in space, etc., are going to be an important part of the future’s space missions....
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...On Orbit Services (OSS) [1], such as orbital detritus management, refurbishment and refuelling of orbiting satellites, construction in space, etc....
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01 Feb 1995
TL;DR: A new formulation of the extended Jacobian method is described that is well suited numerically for systems with multiple degrees of redundancy and for more general choices of the secondary criterion.
Abstract: The extended Jacobian method resolves the redundancy of a kinematically redundant manipulator such that a secondary criterion is kept at an optimal value. This paper describes a new formulation of this algorithm that is well suited numerically for systems with multiple degrees of redundancy and for more general choices of the secondary criterion. This formulation is used here for tracing algorithmic singularities, which mark a boundary of operation for any algorithm using the same secondary criterion to resolve the redundancy. Examples of tracing algorithmic singularities are presented for both planar and spatial systems. >
80 citations
"Switching method to avoid algorithm..." refers methods in this paper
...The methods shown in [15], [16], [17] helped in taking care of the algorithmic singularity, however, at the cost of compromise on the secondary task....
[...]
24 Apr 2000
TL;DR: In this paper, an on-board autonomy "machine vision" is highly required to perform this dynamic task, since a control loop including the ground station tends to be unstable due to the communication time delay between a ground station and a space robot.
Abstract: On-orbit service such as refuelling, repairing and re-orbiting is highly required for space activities. For on-orbit service, it is one of the most important and most difficult technique to capture a "customer satellite" by a robot arm which can move dynamically in a wide range of space. An on-board autonomy "machine vision" is highly required to perform this dynamic task, since a control loop including the ground station tends to be unstable due to the communication time delay between a ground station and a space robot. An experiment was conducted using the Japanese Engineering Test Satellite VII (ETS-VII) to capture a free floating satellite on orbit first time in the world. Successful results of the experiment are presented.
72 citations