Robotic pinching by means of a pair of soft fingers with sensory feedback

It is well known that three frictionless fingers suffice to immobilize any 2D object with triangular shape but four fingers are necessary for a parallelepiped. However, it has been recently shown that only two fingers are enough to realize secure grasp of a rigid object with parallel flat surfaces in a dynamic sense if finger ends have a hemispherical shape with appropriate radius and thereby rollings are induced between finger ends and object surfaces. This paper focuses on the two problems: (1) dynamic force/torque balance of 2D polygonal objects under the effect of gravity force by means of a pair of rolling contacts and (2) concurrent realization of dynamically secure grasp and orientation control of 2D polygonal objects by using a pair of multi-fingered hands with hemispherical ends and sensory feedback signals without knowing object kinematics and mass center. It is shown that the force/torque balance can be attained by controlling both the contact positions and inducing adequate forces in both normal and tangential directions at each of contact points indirectly through finger joints without knowing object mass center and other kinematic parameters.

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“…16 and 17. A partial experimental result on this problem is found in our previous paper 18 and also a recent one. 19…”

Section: Introductionmentioning

confidence: 59%

Dynamic force/torque balance of 2D polygonal objects by a pair of rolling contacts and sensory‐motor coordination

et al. 2003

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“…OBJECT It is said that the posture control of a grasped object by means of two-fingered robotic hands requires totally three joints at least in the hand system [15]. In this section, we show that the object posture control can be realized even in the minimal DOF robotic hand with two rotational joints.…”

Section: Simulation: Posture Control Of a Graspedmentioning

confidence: 85%

A two-phased object orientation controller on soft finger operations

Inoue

Hirai

2007

2007 IEEE/RSJ International Conference on Intelligent Robots and Systems

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Abstract-The greatest characteristic of soft-fingered manipulation is its softness and flexibility during manipulating operations. In previous works, this intrinsic property had been quantitatively explained from the viewpoint of physical and mechanical perspective that the deformation energy induced by large elastic distortion automatically has a minimum equilibrium point. Hence this report first derive equations of motion of two-fingered soft finger robotic hand on the basis of energybased analysis, and explain that an equilibrium point on a combined energy function exists even in the case of manipulating motions by the hand. In this paper, the equilibrium point is called LMEEwC that is unfolded as Local Minimum of Elastic Energy with Constraints. Next, we show that the posture control of a rigid object grasped by the minimal degrees-of-freedom hand can easily be achieved by applying a two-phased controller associated with each joint angle of the hand, which is newly proposed in this report. This control scheme is constructed by two parts: a PD controller with respect to the finger angle and an integral controller with respect to the orientation of the grasped object. The characteristics of the control method of the latter part is that the desired joint angle of the hand is produced dynamically by the integral controller with respect to the object orientation. Finally, we clarify the effectiveness of the proposed control method in the case of the soft-fingered manipulation.

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“…This method is shown to be highly efficient from a computational point of view, however it is cur- rently applied for two-dimensional cases using a Coulomb friction model. The problem of controlling a robotic finger when the dynamic properties of the deformable fingerpad are unknown is discussed in [9], and the control of soft finger rolling manipulation in [5].…”

Section: Related Workmentioning

confidence: 99%

Soft Finger Model with Adaptive Contact Geometry for Grasping and Manipulation Tasks

Ciocarlie

Lackner

Allen

2007

Second Joint EuroHaptics Conference and Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems (WHC'07

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This paper presents a method for building analytical contact models for soft fingers. Friction constraints are derived based on general expressions for non-planar contacts of elastic bodies, taking into account the local geometry and structure of the objects in contact. These constraints are then formulated as a linear complementarity problem, the solution of which provides the normal and frictional forces applied at each contact, as well as the relative velocity of the bodies involved. This approach captures frictional effects such as coupling between tangential force and frictional torque. We illustrate this method by analyzing manipulation tasks performed by an anthropomorphic robotic hand equipped with soft fingerpads.

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Robotic pinching by means of a pair of soft fingers with sensory feedback

Cited by 22 publications

References 4 publications

Dynamic force/torque balance of 2D polygonal objects by a pair of rolling contacts and sensory‐motor coordination

Dynamic force/torque balance of 2D polygonal objects by a pair of rolling contacts and sensory‐motor coordination

A two-phased object orientation controller on soft finger operations

Soft Finger Model with Adaptive Contact Geometry for Grasping and Manipulation Tasks

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