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Partial feedback linearization of underactuated mechanical systems
 In Proceedings of the IEEE International Conference on Intelligent Robots and Systems
, 1994
"... Abstract things as actuator dynamics in the model description. In this paper we discuss.the partial feedback linearization control of underactuated mechanical systems. We consider an n degree of freedom system having m actuated, or active, degrees of freedom and B = n m unactuated, or passive, de ..."
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Cited by 38 (0 self)
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Abstract things as actuator dynamics in the model description. In this paper we discuss.the partial feedback linearization control of underactuated mechanical systems. We consider an n degree of freedom system having m actuated, or active, degrees of freedom and B = n m unactuated, or passive, degrees of freedom. It is known that the portion of the dynamics corresponding to the active degrees of freedom may be linearized by nonlinear feedback. In this paper we show, alternatively, that the portion of the dynamics corresponding to the passive degrees of freedom may be linearized by nonlinear feedback under a condition that we call Strong Inertial Coupling. We derive and analyze the resulting zero dynamics which are crucial to an understanding of the response of the overall system. Simulation results are presented showing the performance of two link underactuated robots under partial feedback linearization control. 1
Smooth Planning for Freefloating Space Robots Using Polynomials
 Proc. 2005 IEEE/ICRA Intl. Conf. On Robotics and Automation
, 2005
"... Abstract�Freefloating space manipulator systems, have spacecraft actuators turned off and exhibit nonholonomic behavior due to angular momentum conservation. A path planning methodology for planar free–floating space manipulator systems is developed that allows simultaneous manipulator endpoint an ..."
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Cited by 8 (4 self)
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Abstract�Freefloating space manipulator systems, have spacecraft actuators turned off and exhibit nonholonomic behavior due to angular momentum conservation. A path planning methodology for planar free–floating space manipulator systems is developed that allows simultaneous manipulator endpoint and spacecraft attitude control using manipulator actuators only. The method is based on mapping the angular momentum to a space where it can be satisfied trivially. Smooth and continuous functions such as polynomials are employed driving the system to a desired configuration. It is shown that the method allows for smooth configuration changes in finite and prescribed time, without requiring small cyclical motions. Limitations are discussed and examples are presented. Index Terms�Space freefloating robots, nonholonomic planning, underactuated systems. I.
Pointtopoint planning: Methodologies for underactuated space robots
 IEEE International Conference on Robotics and Automation (ICRA
, 2006
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The effect of dynamic singularities on robotic control and design
 In Robotics and Automation (ICRA), 2010 IEEE International Conference on
, 2010
"... Abstract — This paper presents the definition of a new type of dynamic singularity for robotic manipulators. It is applicable to all underactuated robotic systems that can be described by Lagrange’s equations where the Lagrangian is the kinetic minus potential energy. The approach is to decompose th ..."
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Abstract — This paper presents the definition of a new type of dynamic singularity for robotic manipulators. It is applicable to all underactuated robotic systems that can be described by Lagrange’s equations where the Lagrangian is the kinetic minus potential energy. The approach is to decompose the velocity at every point in the configuration space into velocity directions that can be directly controlled and those that are uncontrolled and orthogonal to the directly controlled directions. These uncontrolled directions are controlled only through the dynamic coupling with the controlled directions and the measure of a dynamic singularity is then a measure of this degree of coupling. When this coupling is zero, the mechanism is said to be at a dynamic singularity. The practical implication is that, at such points, the dynamics are decoupled and control over the uncontrolled directions is very weak in that the mechanism will have to move away from the singularity before the inputs can affect the uncontrolled velocity directions. An example that is realistically complicated is presented and simulations show the effect on control inputs when the system is operating near a dynamic singularity. I.
A PATH PLANNING METHOD FOR UNDERACTUATED SPACE ROBOTS
"... In freefloating mode, space manipulator systems have their thrusters off, and exhibit nonholonomic behavior due to angular momentum conservation. The system is underactuated and a challenging problem is to control both the end effector location and the base attitude, using manipulator actuators onl ..."
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In freefloating mode, space manipulator systems have their thrusters off, and exhibit nonholonomic behavior due to angular momentum conservation. The system is underactuated and a challenging problem is to control both the end effector location and the base attitude, using manipulator actuators only. Here, a path planning methodology satisfying this double goal is presented. The key idea is to use high order polynomials as arguments in cosines, specifying a desired path directly in jointspace, drastically extending configuration accessibility. The initial problem is converted to one of satisfying the motion integrals by optimization techniques. This approach always leads to a path, provided that the desired change in configuration lies between physically permissible limits. The method is presented for 3D systems. The resulting paths are smooth, avoid the need for small cyclical motions, and lead to smooth changes in finite and prescribed time. 1.
Acquisitions et services bibliographiques
, 1999
"... copies of this tbesis in microform, paper or electronic formats. The author retains ownership of the copyright in this thesis. Neither the thesis nor substantial extracts fiom it may be printed or otherwise reproduced without the author ' s permission. L'auteur a accordé une Licence non ex ..."
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copies of this tbesis in microform, paper or electronic formats. The author retains ownership of the copyright in this thesis. Neither the thesis nor substantial extracts fiom it may be printed or otherwise reproduced without the author ' s permission. L'auteur a accordé une Licence non exclusive permettant à la Bibliothèque nationale du Canada de reproduire, prêter, distribuer ou vendre des copies de cette thèse sous la fome de microfichelfilm, de reproduction sur papier ou sur format
Development of teleoperation control for a freefloating robot during the grasping of a tumbling target
"... This paper addresses the singularities avoidance problem while performing a grasping maneuver in teleoperation with a manipulator mounted on a freefloating spacecraft. Firstly, the independence of the singularities of the endeffector Jacobian of a generic freefloating system from the inertial pa ..."
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This paper addresses the singularities avoidance problem while performing a grasping maneuver in teleoperation with a manipulator mounted on a freefloating spacecraft. Firstly, the independence of the singularities of the endeffector Jacobian of a generic freefloating system from the inertial parameters of the last link is demonstrated. Secondly, the possibility to represent all the singularities in the Cartesian space for a freefloating system provided with three reaction wheels is shown. Finally an optimization algorithm is presented, which provides the optimal spacecraft initial Cartesian position and attitude, to allow the operator to keep a trajectory in the vicinity of the nominal motion while satisfying operational constrains as long as possible. 1
On Configuration Planning for Freefloating Space Robots
"... Abstract. Free–floating space manipulator systems, have spacecraft actuators turned off and exhibit nonholonomic behavior due to angular momentum conservation. A path planning methodology in joint space for planar free–floating space manipulator systems is developed that allows spacecraft attitude c ..."
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Abstract. Free–floating space manipulator systems, have spacecraft actuators turned off and exhibit nonholonomic behavior due to angular momentum conservation. A path planning methodology in joint space for planar free–floating space manipulator systems is developed that allows spacecraft attitude control using manipulator motions. The method is based on mapping the angular momentum to a space where it can be satisfied trivially. Smooth and continuous functions such as polynomials are employed and the system is driven to a desired configuration. Two cases are studied. In the first, the manipulator is mounted on an arbitrary point of the spacecraft and the corresponding transformation is found. Then, a second transformation is found for the particular case where the manipulator is mounted on the center of mass of the spacecraft. It is shown that the derived transformation allows for smooth configuration changes in finite time. Limitations in reaching arbitrary final systems configurations are discussed. The application of the methodology is illustrated using an example. I.
UNDERACTUATED SPACE ROBOTS: PHYSICAL and ALGORITHMIC CONSTRAINTS in SMOOTH MOTION PLANNING
"... Space manipulator systems having spacecraft actuators turned off, operate in freefloating mode, and exhibit nonholonomic behaviour due to angular momentum conservation. The system is underactuated and a challenging problem is to control both the location of the end effector and the attitude of the ..."
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Space manipulator systems having spacecraft actuators turned off, operate in freefloating mode, and exhibit nonholonomic behaviour due to angular momentum conservation. The system is underactuated and a challenging problem is to control both the location of the end effector and the attitude of the base, using manipulator actuators only. A developed path planning method that perform this task is briefly presented and the constraints of motion, both physical and algorithmic, are examined. The physical limitations are imposed by system’s dynamic parameters. Lower and upper bounds for base rotation, due to manipulator motions, are estimated. Smooth functions such as polynomials are employed in the planning scheme, leading to smooth configuration changes in finite and prescribed time, and avoiding many small cyclical motions. Algorithmic limitations of the method in reaching arbitrary final configurations are discussed and examples are presented. KEY WORDS Space freefloating robots, underactuated, nonholonomic planning. 1.