# Classical Grasp Quality Evaluation: New Theory and Algorithms

Florian T. Pokorny, Danica Kragic
In IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2013

## Abstract

This paper investigates theoretical properties of a well-known $L^1$ grasp quality measure $Q$ whose approximation $Q_l^-$ is commonly used for the evaluation of grasps and where the precision of $Q_l^-$ depends on an approximation of a cone by a convex polyhedral cone with $l$ edges. We prove the Lipschitz continuity of $Q$ and provide an explicit Lipschitz bound that can be used to infer the stability of grasps lying in a neighbourhood of a known grasp. We think of $Q_l^-$ as a lower bound estimate to $Q$ and describe an algorithm for computing an upper bound $Q^+$. We provide worst-case error bounds relating $Q$ and $Q_l^-$. Furthermore, we develop a novel grasp hypothesis rejection algorithm which can exclude unstable grasps much faster than current implementations. Our algorithm is based on a formulation of the grasp quality evaluation problem as an optimization problem, and we show how our algorithm can be used to improve the efficiency of sampling based grasp hypotheses generation methods.

## Bibtex

@inproceedings{pokorny2013c, author = {Pokorny, Florian T. and Kragic, Danica}, booktitle = {IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)}, title = {Classical Grasp Quality Evaluation: New Theory and Algorithms}, year = {2013}, address = {Tokyo, Japan}, url = {http://www.csc.kth.se/~fpokorny/static/publications/pokorny2013c.pdf}, } 

## FastGrasp v0.1 (C++/Python)

This C++ library with python bindings implements fast grasp quality evaluation methods outlined in our paper

"Classical Grasp Quality Evaluation: New Theory and Algorithms", F. T. Pokorny, D. Kragic, IEEE/RSJ IROS, 2013

## RandomGrasps

This data set contains 100000 random grasp point-contact configurations formed by uniformly sampled contact points and unit surface normals as well as associated centres of mass. These contact configurations are useful for large scale statistical studies of grasp quality measures but do not necessarily correspond to specific object/hand configurations. Associated grasp quality scores are available for download for further analysis. See the following papers for use cases:

"Classical Grasp Quality Evaluation: New Theory and Algorithms", F. T. Pokorny, D. Kragic, IEEE/RSJ IROS, 2013
"Friction Coefficients and Grasp Synthesis", K. Hang, F. T. Pokorny, D. Kragic, IEEE/RSJ IROS, 2013
"Grasp Moduli Spaces", F. T. Pokorny, K. Hang, D. Kragic, RSS 2013.