In this paper, we survey the field of robotic grasping and the work that has been done in this area over the last two decades, with a slight bias toward the development of the theoretical framework and analytical results in this area.

Robotic grasping and contact: a review

In this paper, an attempt at summarizing the evolution and the state of the art in the field of robot hands is made. In such exposition, a critical evaluation of what in the author's view are the leading ideas and emerging trends is privileged with respect to exhaustiveness of citations. The survey is focused mainly on three types of functional requirements a machine hand can be assigned in an artificial system, namely, manipulative dexterity, grasp robustness, and human operability. A basic distinction is made between hands designed for mimicking the human anatomy and physiology,and hands designed to meet restricted, practical requirements. In the latter domain, arguments are presented in favor of a -minimalistic" attitude in the design of hands for practical applications, i.e., use the least number of actuators, the simplest set of sensors, etc., for a given task. To achieve this rather obvious engineering goal is a challenge to our community. The paper illustrates some of the new sometimes difficult, problems that are brought about by building and controlling simpler, more practical devices.

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Hands for dexterous manipulation and robust grasping: a difficult road toward simplicity

In this paper we analyze in some detail the geometry of a pair of cameras, i.e., a stereo rig. Contrarily to what has been done in the past and is still done currently, for example in stereo or motion analysis, we do not assume that the intrinsic parameters of the cameras are known (coordinates of the principal points, pixels aspect ratio and focal lengths). This is important for two reasons. First, it is more realistic in applications where these parameters may vary according to the task (active vision). Second, the general case considered here, captures all the relevant information that is necessary for establishing correspondences between two pairs of images. This information is fundamentally projective and is hidden in a confusing manner in the commonly used formalism of the Essential matrix introduced by Longuet-Higgins (1981). This paper clarifies the projective nature of the correspondence problem in stereo and shows that the epipolar geometry can be summarized in one 3×3 matrix of rank 2 which we propose to call the Fundamental matrix. After this theoretical analysis, we embark on the task of estimating the Fundamental matrix from point correspondences, a task which is of practical importance. We analyze theoretically, and compare experimentally using synthetic and real data, several methods of estimation. The problem of the stability of the estimation is studied from two complementary viewpoints. First we show that there is an interesting relationship between the Fundamental matrix and three-dimensional planes which induce homographies between the images and create unstabilities in the estimation procedures. Second, we point to a deep relation between the unstability of the estimation procedure and the presence in the scene of so-called critical surfaces which have been studied in the context of motion analysis. Finally we conclude by stressing the fact that we believe that the Fundamental matrix will play a crucial role in future applications of three-dimensional Computer Vision by greatly increasing its versatility, robustness and hence applicability to real difficult problems.

The Fundamental Matrix: Theory, Algorithms, and Stability Analysis

https://hal.archives-ouvertes.fr/hal-00731127/document

An overview of 3D object grasp synthesis algorithms

The correct grasp of objects is a key aspect for the right fulfillment of a given task. Obtaining a good grasp requires algorithms to automatically determine proper contact points on the object as well as proper hand configurations, especially when dexterous manipulation is desired, and the quantification of a good grasp requires the definition of suitable grasp quality measures. This article reviews the quality measures proposed in the literature to evaluate grasp quality. The quality measures are classified into two groups according to the main aspect they evaluate: location of contact points on the object and hand configuration. The approaches that combine different measures from the two previous groups to obtain a global quality measure are also reviewed, as well as some measures related to human hand studies and grasp performance. Several examples are presented to illustrate and compare the performance of the reviewed measures.

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Grasp quality measures: review and performance

This paper uses (linearized) Kalman filters to estimate first-order geometric parameters (i.e., orientation of contact normals and location of contact points) that occur in force-controlled compliant motions. The time variance of these parameters is also estimated. In addition, transitions between contact situations can be monitored. The contact between the manipulated object and its environment is general, i.e., multiple contacts can occur at the same time, and both the topology and the geometry of each single contact are arbitrary. The two major theoretical contributions are (1) the integration of the general contact model, developed previously by the authors, into a state-space form suitable for recursive processing; and (2) the use of the reciprocity constraint between ideal contact forces and motion freedoms as the measurement equation of the Kalman filter. The theory is illustrated by full 3-D experiments. The approach of this paper allows a breakthrough in the state of the art dominated by the classical, orthogonal contact models of Mason that can only cope with a limited (albeit important) subset of all possible contact situations.

Estimating first-order geometric parameters and monitoring contact transitions during force-controlled compliant motion

This article presents a systematic and fully general model- based approach to compliant robot motion, taking into account uncertainties in the geometry of the manipulated object and the environment with which it is in contact. The emphasis is not on control but on modeling, instantaneous motion specification, and on-line uncertainty identification. The presented models are intuitive and yet sufficiently flexible to deal with multiple and time-varying motion constraints between nonpolyhedral objects.The description of the interaction between the manipulated object and its environment starts from first- and second-order approximations of the objects' geometry at the contact points. From these geometric descriptions, the manipulated object's motion freedom—and its dual, the set of possible reaction forces—is modeled up to second order (i.e., accelerations) using the similarity with the kinematics of manipulators. Geometric uncertainties of the manipulated object and the environment, also up to second order (...

Kinematic models for model-based compliant motion in the presence of uncertainty

We develop a geometric framework for the stability analysis of multifingered grasps and propose a measure of grasp stability for arbitrary perturbations and loading conditions. The measure requires a choice of metric on the group of rigid body displacements. We show that although the stability of a grasp itself does not depend on the choice of metric, comparison of the stability of different grasps depends on the metric. Finally, we provide some insight into the choice of metrics for stability analysis.

Generalized stability of compliant grasps

Total knee arthroplasty requires accurate preparation of the bone surfaces to maximize bone implant contact area in cementless surgery and to obtain proper joint kinematics and ligament balancing. Robots can make the cuts with the necessary high precision. The purpose of this article is threefold: to propose an alternative method for intraoperative registration using an intramedullary rod and an alternative method for force control using the hybrid force-velocity control scheme; to demonstrate that the accuracy and the surface flatness of the cuts machined by a robot are better than in a conventional operation; and to monitor the machining process and to try to derive some information about the local bone quality from it. The results of the laboratory study are promising: the surface flatness of the tibial plateau, calculated using a least squares method, is 0.1-0.2 mm, which is significantly better than in conventional surgery; and the high angular accuracy of the robot allows the bone cuts to be located precisely. Further, an exponential relation between milling forces and local bone density was established, so measurements of the milling forces can provide the surgeon with on-line information about the local bone quality.

https://www.tandfonline.com/doi/pdf/10.3109/10929089809149840

Machining and Accuracy Studies for a Tibial Knee Implant Using a Force-Controlled Robot

We demonstrate the recovery of 3D structure from multiple images, without attempting to determine the motion between views. The structure is recovered up to a transformation by a 3D linear group — the affine and projective group. The recovery does not require knowledge of camera intrinsic parameters or camera motion.

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S. Demey

Papers

Estimating first-order geometric parameters and monitoring contact transitions during force-controlled compliant motion

Kinematic models for model-based compliant motion in the presence of uncertainty

Generalized stability of compliant grasps

Machining and Accuracy Studies for a Tibial Knee Implant Using a Force-Controlled Robot

Affine and Projective Structure from Motion