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Dynamic Nonprehensile Manipulation: Controllability, Planning, and Experiments
 International Journal of Robotics Research
, 1998
"... We are interested in using low degreeoffreedom robots to perform complex tasks by nonprehensile manipulation (manipulation without a form or forceclosure grasp). By not grasping, the robot can use gravitational, centrifugal, and Coriolis forces as virtual motors to control more degreesof freedo ..."
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Cited by 46 (14 self)
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We are interested in using low degreeoffreedom robots to perform complex tasks by nonprehensile manipulation (manipulation without a form or forceclosure grasp). By not grasping, the robot can use gravitational, centrifugal, and Coriolis forces as virtual motors to control more degreesof freedom of the part. The extra motion freedoms of the part are exhibited as rolling, slipping, and free flight.
Controllability Tests for Mechanical Systems with Symmetries and Constraints
 J. Applied Mathematics and Computer Science
, 1997
"... This paper derives controllability tests for a large class of mechanical systems characterized by nonholonomic constraints and symmetries. Recent research in geometric mechanics has led to a single, simplified framework that describes this class of systems, which includes examples such as wheeled mo ..."
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Cited by 16 (7 self)
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This paper derives controllability tests for a large class of mechanical systems characterized by nonholonomic constraints and symmetries. Recent research in geometric mechanics has led to a single, simplified framework that describes this class of systems, which includes examples such as wheeled mobile robots; undulatory robotic and biological locomotion systems, such as paramecia, inchworms, and snakes; and the reorientation of satellites and underwater vehicles. This geometric framework has also been applied to more unusual examples, such as the snakeboard robot, the wobblestone, and the reorientation of a falling cat. Using modern results from nonlinear control theory, we develop accessibility and controllability tests based on this reduced geometric structure. We also discuss parallels between these tests and the construction of openloop control algorithms, with analogies to the generation of locomotive gaits for robotic systems. 1 Introduction M ECHANICAL systems provide a f...
Controllability of a Planar Body with Unilateral Thrusters
 IEEE Trans. on Automatic Control
, 1999
"... This note investigates the minimal number of unilateral thrusters required for different versions of nonlinear controllability of a planar rigid body. For one to three unilateral thrusters, we get a new property with each additional thruster: one thruster yields smalltime accessibility on the body& ..."
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Cited by 16 (6 self)
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This note investigates the minimal number of unilateral thrusters required for different versions of nonlinear controllability of a planar rigid body. For one to three unilateral thrusters, we get a new property with each additional thruster: one thruster yields smalltime accessibility on the body's state space TSE(2); two thrusters yield global controllability on TSE(2); and three thrusters yield smalltime local controllability at zero velocity states.
Dynamic Manipulation With a One Joint Robot
 IN PROCEEDINGS OF THE 1997 IEEE INTERNATIONAL CONFERENCE ON ROBOTICS AND AUTOMATION
, 1997
"... We are interested in using low degreeoffreedom robots to perform complex manipulation tasks by not grasping. By not grasping, the robot can use rolling, slipping, and free flight to control more degreesoffreedom of the part. To demonstrate this we study the controllability properties of planar d ..."
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Cited by 7 (1 self)
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We are interested in using low degreeoffreedom robots to perform complex manipulation tasks by not grasping. By not grasping, the robot can use rolling, slipping, and free flight to control more degreesoffreedom of the part. To demonstrate this we study the controllability properties of planar dynamic nonprehensile manipulation. We show that almost any planar object is smalltime locally controllable by point contact, and the controlling robot requires only two degreesoffreedom (a point translating in the plane). We then focus on a one joint manipulator (with a twodimensional state space) and show that even this simplest of robots, by using slipping and rolling, can control an object to a fulldimensional subset of its sixdimensional state space. We have developed a one joint robot to perform a variety of dynamic tasks, including snatching an object from a table, rolling an object on the surface of the arm, and throwing and catching.
Doctoral Dissertation! Analytical Approach to Position and Attitude Control of an Underactuated Satellite!
, 2013
"... Contents List of figures 2 ..."
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Autonomous Thruster Failure Recovery for Underactuated Spacecraft
, 2010
"... Thruster failures historically account for a large percentage of failures that have occurred on orbit. Therefore, autonomous thruster failure detection, isolation, and recovery (FDIR) is an essential component to any robust spacebased system. This thesis focuses specifically on developing thruster ..."
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Thruster failures historically account for a large percentage of failures that have occurred on orbit. Therefore, autonomous thruster failure detection, isolation, and recovery (FDIR) is an essential component to any robust spacebased system. This thesis focuses specifically on developing thruster failure recovery techniques as there exist many proven thruster FDI algorithms. Typically, thruster failures are handled through redundancyif a thruster fails, control can be allocated to other operational thrusters. However, with the increasing push to using smaller, less expensive satellites there is a need to perform thruster failure recovery without additional hardware, which would add extra mass, volume, and complexity to the spacecraft. This means that a thruster failure may cause the spacecraft to become underactuated, requiring more advanced control techniques. Therefore, the objective of this thesis is to develop and analyze thruster failure recovery techniques for the attitude and translational control of underactuated spacecraft. To achieve this objective, first, a model of a thrustercontrolled spacecraft is de
Acknowledgements
, 1998
"... iii Many people positively influenced my work on this thesis. In particular, my advisor Dr. Joel Burdick was always available for guidance, insight, wisdom and perspective. Of course, without his help, my work would not have been possible. Additionally, Dr. Richard Murray also provided much help and ..."
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iii Many people positively influenced my work on this thesis. In particular, my advisor Dr. Joel Burdick was always available for guidance, insight, wisdom and perspective. Of course, without his help, my work would not have been possible. Additionally, Dr. Richard Murray also provided much help and guidance. Also, it was his classes in differential geometry and nonlinear control that provided the initial inspiration for my research. I would also like to thank the other members of my committee, Dr. Jerry Marsden, Dr. Tom Caughey and Dr. Erik Antonsson. In retrospect, I realize that both individually and collectively the well–earned reputation of my committee could not be matched anywhere but Caltech, and I feel fortunate to have such a distinguished committee. Gábor Stépán and Shuuji Kajita have also provided inspirational scientific enthusiasm and friendship. Several (former) fellow graduate students also shared similar research interests, and many discussions with them were very valuable and enjoyable. In particular, Andrew Lewis provided quite a bit of guidance and Francesco Bullo shared an incredible enthusiasm for his (and my) work that proved very inspirational. I would also like to thank the rest of my fellow graduate students (collectively known as “SOPS”) for making my time at Caltech very enjoyable, including but not
Bilateral TimeScaling for Control of Task Freedoms of a
"... We explore the control of a nonholonomic robot subject to additional constraints on the state variables. In our problem, the user specifies the path of a sub set of the state variables (the task freedoms xp), i.e. a curve Xp(S) where s G [0,1] is a parametrization that the user chooses. We control ..."
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We explore the control of a nonholonomic robot subject to additional constraints on the state variables. In our problem, the user specifies the path of a sub set of the state variables (the task freedoms xp), i.e. a curve Xp(S) where s G [0,1] is a parametrization that the user chooses. We control the trajectory of the task freedoms by specifying a bilateral timescaling which assigns a point on the path for each t G [0, T], where T is the time to completion of the path. The timescaling is termed bilateral because there is no re striction on $(t), the task freedoms are allowed to move backwards along the path. We design a controller that satisfies the user directive and controls the remaining state variables (the shape freedoms xR) such that the constraints are satisfied. Furthermore, we attempt to reduce the number of control switchings, as these result in relatively large errors in our system state. If a constraint is close to being violated (at a switching point), we back up xp along the path for a small time interval and move x$ to an open region. We show that there are a finite number of switching points for arbitrary task freedom paths. We implement our control scheme on the Mobipulator and discuss a generalization to arbitrary systems satisfying similar properties.