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Jijie Xu

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15 papers

1 author row

IROS Conference 2010 Conference Paper

Enhanced bimanual manipulation assistance with the Personal Mobility and Manipulation Appliance (PerMMA)

Jijie Xu
Garrett Grindle
Ben Salatin
Juan Jose Vazquez Lopez
Hongwu Wang
Dan Ding
Rory A. Cooper

In this paper, we investigate the enhanced ability of manipulation with the newly developed Personal Mobility and Manipulation Appliance (PerMMA). PerMMA is a new assistive device that integrates bimanual manipulation with smart mobility to assist people with severe physical disabilities and enhance their quality of lives. Different from the fixed mounting method used in most existing systems, a novel mounting system was designed on PerMMA to enhance its capability of manipulation assistance. With a workspace characterized by essential daily living tasks, we evaluated PerMMA's performance of manipulation using a comparative study between PerMMA and classic design, such as single arm and fixed mounting, used in most existing systems. Simulation results demonstrate significant improvements with PerMMA in both of its reachability and manipulability.

IROS Conference 2009 Conference Paper

Planning fireworks trajectories for steerable medical needles to reduce patient trauma

Jijie Xu
Vincent Duindam
Ron Alterovitz
Jean Pouliot
J. Adam M. Cunha
I-Chow Hsu
Ken Goldberg

Accurate insertion of needles to targets in 3D anatomy is required for numerous medical procedures. To reduce patient trauma, a ¿fireworks¿ needle insertion approach can be used in which multiple needles are inserted from a single small region on the patient's skin to multiple targets in the tissue. In this paper, we explore motion planning for ¿fireworks¿ needle insertion in 3D environments by developing an algorithm based on Rapidly-exploring Random Trees (RRTs). Given a set of targets, we propose an algorithm to quickly explore the configuration space by building a forest of RRTs and to find feasible plans for multiple steerable needles from a single entry region. We present two path selection algorithms with different optimality considerations to optimize the final plan among all feasible outputs. Finally, we demonstrate the performance of the proposed algorithm with a simulation based on a prostate cancer treatment environment.

IROS Conference 2007 Conference Paper

Finger gaits planning for multifingered manipulation

Jijie Xu
Tak-Kuen John Koo
Zexiang Li 0001

A robotic hand may change its grasp status and relocate some of its fingers in order to perform a large scale manipulation. Such a strategy is called a finger gait. In this paper, a randomized manipulation planning algorithm is proposed to solving the finger gait planning problem. One of the most used finger gaiting primitives, finger substitution, is introduced. Because of its discrete-continuous characteristics, the kinematics model of a finger substitution is formulated into a hybrid automaton. Considering the discrete and continuous topology of the automaton, both the discrete metric and contin uous metric are defined on the state space. An improved RRT based planner is proposed to find a feasible finger substitution. Finally, simulation results verify the validity of the proposed finger gait planner.

ICRA Conference 2007 Conference Paper

Force Analysis of Whole Hand Grasp by Multifingered Robotic Hand

Jijie Xu
Michael Yu Wang
Hong Wang
Zexiang Li 0001

Under a whole hand grasp, it may not be possible to generate grasping forces in all directions. Thus, the traditional techniques developed based on fingertip contacts is inadequate. In this paper, we decompose the contact force space into four orthogonal subspaces, each with a clear physical interpretation. Based on linear matrix inequalities (LMI's) representations of grasping constraints, we address and formulate the active force closure and the active grasp feasibility problems as LMI feasibility problems. Combining the effects of both active and passive forces, we propose a new cost index for the whole hand grasping force optimization problem. We further simply the force optimization problem for a whole hand grasp, which is active force closure.

IROS Conference 2006 Conference Paper

Grasping Force Optimization for Whole Hand Grasp

Jijie Xu
Yunjiang Lou
Zexiang Li 0001

In tasks of grasping and manipulation, the hand sometimes uses not only fingertips but also fingers' inner links and the palm to achieve more robust grasp. This kind of grasp is called whole hand grasp, or power grasp. One property of whole hand grasp is that the hand may not be able to generate grasping forces in any directions, so previous fingertip grasping analysis is no longer suitable for whole hand grasp. In this paper, concepts of active force and passive force are introduced. With these concepts, the contact force space is decomposed into four orthogonal subspaces. Considering the roles of both active force and passive force, a new cost index is proposed for the whole hand grasping force optimization, which is then reformulated into a convex optimization problem involving LMIs. Finally, numerical example and simulation results verify the validity and performance of our formulation of the problem with that new proposed cost index

IROS Conference 2006 Conference Paper

Hybrid Automaton: A Better Model of Finger Gaits

Jijie Xu
Yunjiang Lou
Zexiang Li 0001

Large-scale motion of the grasped object is one of the tasks, which is involved in practical dextrous manipulation of multifingered robotic hand. When the large-scale motion can not be accomplished only by rolling and sliding of the finger, finger gaiting, or regrasping, is used. In this paper, two primitives of finger gaits are introduced. Based on the characteristic of finger gaits, we model finger gaits as a hybrid automaton. Finally, we do simulations on a three fingered hand to verify the validity of our model

IROS Conference 2005 Conference Paper

Kinematic modelling of multifingered hand's finger gaits as hybrid automaton

Jijie Xu
Zexiang Li 0001

Large-scale motion of the grasped object is one of the tasks, which is involved in practical dexterous manipulation of multifingered robotic hand. When the large-scale motion can not be accomplished only by rolling and sliding of the finger, finger gaiting, or regrasping, is used. In this paper, we propose a joint space representation of grasps, which represents a stable grasp by a set of joints values with several grasping constraints. Using primitives describing the regrasping process with the joint space representation, we build a kinematic model of finger gaiting as a hybrid automaton, by using which all grasping constraints are involved. Then, a simple but representative simulation is setup, whose results verify the validity and efficiency of the model. Finally, we state several interesting future works, which can greatly be extended based on the hybrid automaton we proposed in this paper.

ICRA Conference 2004 Conference Paper

A General Approach for Optimal Kinematic Design of Parallel Manipulators

Yunjiang Lou
Guanfeng Liu 0002
Jijie Xu
Zexiang Li 0001

This paper deals with the problem of optimal geometry design of parallel manipulators. In order to reduce the main drawbacks of parallel manipulators, relatively small workspace and more singularities, two requirements, workspace and condition number, are considered. The design problem is thus formulated to find a parallel mechanism such that its Cartesian workspace contains a prescribed workspaces with good condition numbers in it. By observing that those requirements can be locally cast into Linear Matrix Inequalities (LMIs), we formulate the design problem locally as a convex optimization problem subject to LMIs with a max-det function as its objective function. Hence, at each node of discretized space of design parameters, there is an LMI-based convex optimization problem. A two-level algorithm can be applied to solve for a set of optimal design parameters: (1) Discretize the space of design parameters into a set of discrete nodes; (2) At each node the Newton algorithm is applied to solve the max-det optimization problem. By comparing all the locally optimal costs, we can obtain a corresponding set of globally optimal design parameters correspondingly. Simulation results verify the effectiveness of the proposed approach.

ICRA Conference 2004 Conference Paper

On Quality Functions for Grasp Synthesis and Fixture Planning

Jijie Xu
Guanfeng Liu 0002
Zexiang Li 0001

Planning a proper set of contact points on a given object/workpiece so as to satisfy a certain optimality criterion is a common problem in grasp synthesis for multi-fingered robotic hands and in fixture planning for manufacturing automation. We formulate the grasp-planning problem as optimization problems with respect to several grasp quality functions. For real-time computation, a simplified min-analytic-center problem is proposed. Simulation and experimental results illustrate the validity of the proposed approach for optimal grasp planning.

ICRA Conference 2003 Conference Paper

A comparative study of geometric algorithms for real-time grasping force optimization

Guanfeng Liu 0002
Jijie Xu
Zexiang Li 0001

Real-time grasping force optimization problem can be naturally formulated as a convex optimization problem on the Riemannian manifold of positive definite matrices subject to linear constraints for which many algorithms, including gradient algorithms, Newton algorithms, and interior point algorithms, have been developed. In all these algorithms we need to specify a step size in every iteration and a valid initial point to start the recursion. In this paper we propose several strategies for selecting such a step size according to the properties of each algorithm and one method for searching a valid initial point. Simulation and experimental results show the different performances of these algorithms from computation time and convergence rates.

IROS Conference 2003 Conference Paper

A study on geometric algorithms for real-time grasping force optimization

Jijie Xu
Guanfeng Liu 0002
Xin Wang
Zexiang Li 0001

In this paper we propose several strategies for selecting such a step size according to the properties of each algorithm and a method for searching a valid initial point. By investigating the structure of the affine-scaling vector fields associated with the optimization problem, we give a detailed convergence analysis of these algorithms. Simulation and experimental results show the different performance of these algorithms from computation time and convergence rates.

IROS Conference 2003 Conference Paper

A study on quality functions for grasp synthesis and fixture planning

Jijie Xu
Guanfeng Liu 0002
Xin Wang
Zexiang Li 0001

Planning a proper set of contact points on a given object/workpiece so as to satisfy a certain optimality criterion is a common problem in grasp synthesis for multifingered robotic hands and in fixture planning for manufacturing automation. In this paper, we formulate the grasp planning problem as optimization problems with respect to two grasp quality functions. For real-time computation, a simplified Min-analytic-center problem is proposed. Simulation and experimental results illustrate the validity of the proposed approach for optimal grasp planning.

ICRA Conference 2003 Conference Paper

Convergence analysis and experimental study of geometric algorithms for real-time grasping force optimization

Guanfeng Liu 0002
Jijie Xu
Zexiang Li 0001

Real-time grasping force optimization problem can be naturally formulated as a convex optimization problem on the Riemannian manifold of positive definite matrices subject to linear constraints for which many algorithms, including gradient algorithms, Newton algorithms, and interior point algorithms, have been developed. In all these algorithms we need to specify a step size in every iteration. In this paper we propose several strategies for selecting such a step size according to the properties of each algorithm. By investigating the structure of the affine-scaling vector fields associated with the optimization problem, we give a detailed convergence analysis of these algorithms. Experimental results show the different performance of these algorithms from convergence rates.

IROS Conference 2003 Conference Paper

Kinematic synthesis of parallel manipulators: a Lie theoretic approach

Guanfeng Liu 0002
Jian Meng
Jijie Xu
Zexiang Li 0001

This paper provided a unified geometric framework for kinematic analysis and synthesis of parallel manipulators. We gave a strict definition on motion types of a mechanism based on distributions on a Lie group. We derived conditions for parallel manipulators with Lie subgroup motions using the intersection of the permissible velocity spaces, or the direct sum of the constraint force spaces of each subchain, and the integration theory on a Lie group. Several practical examples were studied in detail to verify our approach.

IROS Conference 2002 Conference Paper

Automatic real-time grasping force determination for multifingered manipulation: theory and experiments

Guanfeng Liu 0002
Jijie Xu
Zexiang Li 0001

This article deals with the problem of real-time grasping force optimization for multifingered manipulation. Based on a review of existing approaches, the BHM and the HTL algorithms, a need for a strictly possible initial solution is found to be a common problem. Two approaches, the max-det approach and min-max approach, are proposed to resolve this problem. The first approach, although efficient in most cases, suffers from the problem of singularity. The latter can resolve the singularity problem, but is relatively slow compared with the former. The two approaches are combined in real implementations to efficiently compute a strictly initial solution, which is in turn used in the HTL algorithm (also the BHM algorithm). The whole algorithm is shown to be fast, fully automatic, and applicable to a wide class of manipulation tasks irrespective of the number of fingers and also the geometry of the manipulated objects. Experiments on the HKUST hand demonstrate the convergence and speed of the algorithm.