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This paper presents a new control scheme for dexterous manipulation of an object by a multifingered hand. The aim of this control is to ensure the tracking by the object of specific trajectories depending on the task. More specifically, we consider a decoupling control according to the motion directions in the task space. The control scheme is based on a new eigenstructure assignment method, where...
This paper presents a new control scheme for dexterous manipulation of an object by a multifingered hand. The effects of the uncertainties on the contact orientation and location are investigated and taken into account in the control design, allowing to manipulate the object robustly. The control law has three main objectives: (i) ensuring the motion control of the object, (ii) satisfying the constraints...
This paper presents an analysis of object grasping with a multifingered robot hand. Uncertainties on the contact orientation and location are investigated and taken into account to find a new grasp quality measure. This new metric allows to evaluate the controllability of the system and find the Reachable Wrench Space under Uncertainties, a new set introduced in this paper. It includes all the wrenches...
The stiffness control of an object grasped by a multi-fingered robot hand requires the modeling of the elastic behavior of the object, caused by the stiffness of the fingers. Because of the presence of rolling contacts between the fingers and the object, such a modeling is not a trivial issue, and a very different one from the case of simpler parallel manipulators. We provide here a first expression...
In this paper, the problem of force feedback control of kinematically defective manipulators (KDMs) is considered. KDMs are robot manipulators that have fewer joints than the dimension of the space in which their end-effector moves. It is well known that controlling the end-effector velocity of an n-joint KDM can be easily solved by appropriately selecting n components of the output twist, thus squaring...
We address the problem of choosing adequate contact forces to ensure the stability of a multi-fingered grasp in face of external disturbances of unknown intensity. The contact forces we look for are tightening, pre-strain forces rather than active, direction-related blocking forces. We compute such tightening forces, together with blocking forces and a lower-bound approximation of an existing grasp...
In the reinforcement learning literature, transfer is the capability to reuse on a new problem what has been learnt from previous experiences on similar problems. Adapting transfer properties for robotics is a useful challenge because it can reduce the time spent in the first exploration phase on a new problem. In this paper we present a transfer framework adapted to the case of a climbing virtual...
While realizing a task, human-beings are able to use grasping inside their environment in order to keep the most stable balance. Although such a behavior is quite natural for humans, it is very difficult to find the best formulation to adapt human motion to humanoid robots. This paper proposes a conceptually simple framework of human posture control based on optimization which takes into account grasp...
Human beings perform complex tasks while even keeping balance. Though this is evident for a human, it is very difficult to adapt human motion to humanoid robots, due to the posture redundancy. In this paper we propose a conceptually simple framework of human posture control, scoping in a general way with grasp, task achievement and being on the same time robust to external disturbances. We do this...
This paper presents a new method allowing haptic feedback in molecular docking simulations using a minimization process. These simulations, classically used by the pharmaceutical industry, for example Sanofl-Aventis, are based on the energy description of atoms to estimate the interactions between a ligand and a protein. The main drawback is that forces and torques cannot be calculated by the means...
This paper presents a new method for a six degrees of freedom haptic feedback in molecular docking simulations in virtual reality. The proposed method allows real-time haptic interaction even in the case of classical molecular simulation which implies notoriously long computation time. These simulations are classically used by the pharmaceutical industry (Sanofi-Aventis) and are based on the energetic...
This paper proposes a novel planning algorithm for image based visual servoing (IBVS). IBVS is conceptually simple but prone to fail in case of large displacements. Hence, the objective is to provide paths for reference points in the image plane, such that the camera is steered from initial position to desired position. The novel scheme guarantees that the camera is always oriented such that the object...
This paper presents a control approach for human grasp simulation in a real-time context. We consider a 12-dof hand grasping quasi-rigid objects, either for fine manipulation or perturbation rejection. The objective is to translate and rotate the object with respect to non-sliding conditions. In order to improve the visual realism and the stability of the simulation, we use a locally deformable model...
In this article, the problem of force feedback control of kinematically constrained manipulators (KCMs) is considered. For these robots, we show that the force component selection approach is not appropriate in general to solve the force control problem. Moreover, by formulating the problem in the joint space, we show how to properly design a stable force controller for KCMs subject to arbitrary external...
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