Results 1  10
of
16
On the Closure Properties of Robotic Grasping
 International Journal of Robotics Research
, 1995
"... The formclosure and forceclosure properties of robotic grasping are investigated. Loosely speaking, these properties are related to the capability of the robot to inhibit motions of the workpiece in spite of externally applied forces. In this paper, formclosure is considered as a purely geomet ..."
Abstract

Cited by 52 (6 self)
 Add to MetaCart
The formclosure and forceclosure properties of robotic grasping are investigated. Loosely speaking, these properties are related to the capability of the robot to inhibit motions of the workpiece in spite of externally applied forces. In this paper, formclosure is considered as a purely geometric property of a set of unilateral (contact) constraints, such as those applied on a workpiece by a mechanical fixture, while forceclosure is related with the capability of the particular robotic device being considered to apply forces through contacts. The concepts of partial form and forceclosure properties are introduced and discussed, and an algorithm is proposed to obtain a synthetic geometric description of partial formclosure constraints. While the literature abounds with formclosure tests, proposed algorithms for testing forceclosure are either approximate or computationally expensive. This paper proves the equivalence of forceclosure analysis with the study of the equ...
Grasp Analysis as Linear Matrix Inequality Problems
"... Three important problems in the study of grasping and manipulation by multifingered robotic hands are: (a) Given a grasp characterized by a set of contact points and the associated contact models, determine if the grasp has force closure; (b) If the grasp does not have force closure, determine if th ..."
Abstract

Cited by 33 (2 self)
 Add to MetaCart
Three important problems in the study of grasping and manipulation by multifingered robotic hands are: (a) Given a grasp characterized by a set of contact points and the associated contact models, determine if the grasp has force closure; (b) If the grasp does not have force closure, determine if the ngers are able to apply a specified resultant wrench on the object; and (c) Compute "optimal" contact forces if the answer to problem (b) is affirmative. In this paper, based on an early result by Buss, Hashimoto and Moore, which transforms the nonlinear friction cone constraints into positive definiteness of certain symmetric matrices, we further cast the friction cone constraints into linear matrix inequalities (LMIs) and formulate all three of the problems stated above as a set of convex optimization problems involving LMIs. The latter problems have been extensively studied in optimization and control community and highly efficient algorithms with polynomial time complexity are now available for their solutions. We perform simulation studies to show the simplicity and efficiency of the LMI formulation to the three problems.
On the Problem of Decomposing Grasp and Manipulation Forces in Multiple WholeLimb Manipulation
, 1994
"... By the term power grasp in the phisiology of human manipulation, a particular type of hold is indicated, that uses not only the fingertips but also the inner phalanges of the hand for constraining the object. In robotics, this concept can be extended to robotic systems composed of multiple actuated ..."
Abstract

Cited by 15 (10 self)
 Add to MetaCart
By the term power grasp in the phisiology of human manipulation, a particular type of hold is indicated, that uses not only the fingertips but also the inner phalanges of the hand for constraining the object. In robotics, this concept can be extended to robotic systems composed of multiple actuated limbs (such as arms, fingers, or legs) cooperating in the manipulation of an object. Power grasp (also indicated by "enveloping" or "wholelimb") operations that exploit any part of the limbs to contact the object are considered in this paper. In particular, the problem of decomposing the system of contact forces exerted between the robot limbs and the object, in order to apply a desired resultant force on the object (and/or to resist external disturbances) is studied. The peculiarity of wholelimb systems is that contacts occurring on links with limited mobility, such as the inner links of a robot arm or hand, and even on fixed links (a robot chest or palm), are possible. Although the pot...
Quadratically Convergent Algorithms for Optimal Dextrous Hand Grasping
 IEEE Transactions on Robotics and Automation
"... Abstract—There is a robotic balancing task, namely realtime dextroushand grasping, for which linearly constrained, positive definite programming gives a quite satisfactory solution from an engineering point of view. We here propose refinements of this approach to reduce the computational effort. T ..."
Abstract

Cited by 14 (3 self)
 Add to MetaCart
Abstract—There is a robotic balancing task, namely realtime dextroushand grasping, for which linearly constrained, positive definite programming gives a quite satisfactory solution from an engineering point of view. We here propose refinements of this approach to reduce the computational effort. The refinements include elimination of structural constraints in the positive definite matrices, orthogonalization of the grasp maps, and giving a precise Newton step size selection rule. Index Terms—Dextrous hand, gradient flow, Newton algorithm, optimal grasping, positive definite programming, Riemannian geometry, robotic hand. I.
Dextrous manipulation from a grasping pose
 ACM Transactions on Graphics
"... This paper introduces an optimizationbased approach to synthesizing hand manipulations from a starting grasping pose. We describe an automatic method that takes as input an initial grasping pose and partial object trajectory, and produces as output physically plausible hand animation that effects t ..."
Abstract

Cited by 13 (1 self)
 Add to MetaCart
This paper introduces an optimizationbased approach to synthesizing hand manipulations from a starting grasping pose. We describe an automatic method that takes as input an initial grasping pose and partial object trajectory, and produces as output physically plausible hand animation that effects the desired manipulation. In response to different dynamic situations during manipulation, our algorithm can generate a range of possible hand manipulations including changes in joint configurations, changes in contact points, and changes in the grasping force. Formulating hand manipulation as an optimization problem is key to our algorithm’s ability to generate a large repertoire of hand motions from limited user input. We introduce an objective function that accentuates the detailed hand motion and contacts adjustment. Furthermore, we describe an optimization method that solves for hand motion and contacts efficiently while taking into account longterm planning of contact forces. Our algorithm does not require any tuning of parameters, nor does it require any prescribed hand motion sequences.
Fast computation of optimal contact forces
 IEEE Transactions on Robotics
, 2007
"... Abstract — We consider the problem of computing the smallest contact forces, with pointcontact friction model, that can hold an object in equilibrium against a known external applied force and torque. It is known that the force optimization problem (FOP) can be formulated as a semidefinite programm ..."
Abstract

Cited by 8 (5 self)
 Add to MetaCart
Abstract — We consider the problem of computing the smallest contact forces, with pointcontact friction model, that can hold an object in equilibrium against a known external applied force and torque. It is known that the force optimization problem (FOP) can be formulated as a semidefinite programming problem (SDP), or a secondorder cone problem (SOCP), and so can be solved using several standard algorithms for these problem classes. In this paper we describe a custom interiorpoint algorithm for solving the FOP that exploits the specific structure of the problem, and is much faster than these standard methods. Our method has a complexity that is linear in the number of contact forces, whereas methods based on generic SDP or SOCP algorithms have complexity that is cubic in the number of forces. Our method is also much faster for smaller problems. We derive a compact dual problem for the FOP, which allows us to rapidly compute lower bounds on the minimum contact force, and to certify infeasibility of a FOP. We use this dual problem to terminate our optimization method with a guaranteed accuracy. Finally, we consider the problem of solving a family of FOPs that are related. This occurs, for example, in determining whether force closure occurs, in analyzing the worstcase contact force required over a set of external forces and torques, and in the problem of choosing contact points on an object so as to minimize the required contact force. Using dual bounds, and a warmstart version of our FOP method, we show how such families of FOPs can be solved very efficiently.
Intrinsic tactile sensing for the optimization of force distribution in a pipe crawling robot
 IEEE/ASME Transactions on Mechatronics
, 2001
"... Abstract—This paper describes a tactile sensing system based on a force/torque sensor for the feet of a pipe crawling robot. Such a sensing system is needed for better optimization of force and joint load distribution and a safer avoidance of the risk of foot slippage. While conventional tactile sen ..."
Abstract

Cited by 6 (0 self)
 Add to MetaCart
Abstract—This paper describes a tactile sensing system based on a force/torque sensor for the feet of a pipe crawling robot. Such a sensing system is needed for better optimization of force and joint load distribution and a safer avoidance of the risk of foot slippage. While conventional tactile sensing devices typically provide information concerning the spatial distribution of normal pressures, the intrinsic contact sensing system presented in this text only measures the three components of the contact force and two components of the resultant torque. These five parameters are shown to be sufficient to estimate the location of the contact point and hence the orientation of the local contact surface. Such information can then be used by the crawler’s control system for the realtime computation of an optimized foot force distribution. The intrinsic tactile sensing method has been experimentally tested on a single leg test setup, while the optimization of force distribution is already functioning in the TUM Pipe Crawling Robot (only with a different, more unripe, sensing system for the contact orientations). Index Terms—Force control, legged locomotion, robot sensing systems, service robots, tactile sensors. I.
Neural Network Control Of Force Distribution For Power Grasp
, 1991
"... The implementation of an Artificial Neural Network (ANN) based power grasp controller is discussed. Multiple points of contact between the grasped object and finger surfaces characterize power grasps and result in highly stable grasps. However, modeling is especially difficult because of the nature ..."
Abstract

Cited by 5 (2 self)
 Add to MetaCart
The implementation of an Artificial Neural Network (ANN) based power grasp controller is discussed. Multiple points of contact between the grasped object and finger surfaces characterize power grasps and result in highly stable grasps. However, modeling is especially difficult because of the nature of the contacts and the resulting closed kinematic structure. Linear programming was used to train an ANN to control the force distribution for objects using a model of the DIGITS Grasping System. Force control is implemented to insure that the maximum normal force applied to the object at the contacts is set to a prespecified level whenever possible. The ANN was able to learn the appropriate nonlinear mapping between the object size and force levels to an acceptable level of accuracy and can be used as a constanttime power grasp controller. 1 Introduction Flexibility in robotic grasping is particularly useful in task domains where the environment is unstructured, such as in planetary expl...
Modeling and Control of a Hybrid Locomotion System
 ASME Journal of Mechanical Design
, 1999
"... This paper describes a hybrid mobility system that combines the advantages of both legged and wheeled locomotion. The legs of the hybrid mobility system permit it to surmount obstacles and navigate difficult terrain, while the wheels allow efficient locomotion on prepared surfaces and provide a reli ..."
Abstract

Cited by 3 (0 self)
 Add to MetaCart
This paper describes a hybrid mobility system that combines the advantages of both legged and wheeled locomotion. The legs of the hybrid mobility system permit it to surmount obstacles and navigate difficult terrain, while the wheels allow efficient locomotion on prepared surfaces and provide a reliable passive mechanism for supporting the weight of the vehicle. We address the modeling, analysis and control of such hybrid mobility systems using the specific example of a wheelchair with two powered rear wheels, two passive front casters, and two articulated, twodegreeoffreedom legs. We exploit the redundancy in actuation to actively control and optimize the contact forces at the feet and the wheels. Our scheme for active traction optimization redistributes the contact forces so as to minimize the largest normalized ratio of tangential to normal forces among all the contacts. Simulation and experimental results for the prototype are presented to demonstrate and evaluate the approach. 1
Newton’s Algorithm in Euclidean Jordan Algebras, with Applications to Robotics
"... Abstract. We consider a convex optimization problem on linearly constrained cones in Euclidean Jordan algebras. The problem is solved using a damped Newton algorithm. Quadratic convergence to the global minimum is shown using an explicit stepsize selection. Moreover, we prove that the algorithm is ..."
Abstract

Cited by 2 (1 self)
 Add to MetaCart
Abstract. We consider a convex optimization problem on linearly constrained cones in Euclidean Jordan algebras. The problem is solved using a damped Newton algorithm. Quadratic convergence to the global minimum is shown using an explicit stepsize selection. Moreover, we prove that the algorithm is a smooth discretization of a Newton flow with Lipschitz continuous derivative. 1. Introduction. It