DOF Finger Research Articles

Designing an underactuated mechanism for a 1 active DOF finger operation

In this paper a novel finger mechanism with 1 active DOF is proposed for an underactuated operation. The underacuation mechanism design is based on spring elements within the mechanism structure. The feasibility of the mechanism is verified through suitable kinematic and static analysis to give performance characteristics. The finger mechanism is able to obtain a human-like grasping operation and it can be embedded within the finger body with human-size mechanical design. The proposed finger mechanism is presented also as obtained from a synthesis procedure which is based on the analyzed characteristics. A design solution is proposed and tested through numerical simulation.

Cooperative Impedance Control of a Finger-Manipulator System in Consideration of Manipulability

In the previous study, a cooperative control algorithm was proposed for a finger-arm robot composed of a 3 DOF finger robot and a 6 DOF arm robot. However, free movement of the robot was only discused in the previous study. This paper describes a control method for a finger-arm robot in order to simulataneously achieve the manipulability control and the impedance control in a three-dimensional space. Firstly, the control loops of the passive impedance control and the active impedance control are developed by using the previous heuristic method, and the experiments are made to examine their features and effects. Secondly, the algorithm of the steepest ascent method to control the manipulability of the finger robot is also proposed for the impedance control. The effectiveness of the proposed method was shown in the optimization process of the manipulability. The proposed method gives advantages of enlarging the impedance space, singularity avoidance and avoidance of unexpected obstacles.

A two DoF finger for a biomechatronic artificial hand

Current prosthetic hands are basically simple grippers with one or two degrees of freedom, which barely restore the capability of the thumb-index pinch. Although most amputees consider this performance as acceptable for usual tasks, there is ample room for improvement by exploiting recent progresses in mechatronics design and technology. We are developing a novel prosthetic hand featured by multiple degrees of freedom, tactile sensing capabilities, and distributed control. Our main goal is to pursue an integrated design approach in order to fulfill critical requirements such as cosmetics, controllability, low weight, low energy consumption and noiselessness. This approach can be synthesized by the definition "biomechatronic design", which means developing mechatronic systems inspired by living beings and able to work harmoniously with them. This paper describes the first implementation of one single finger of a future biomechatronic hand. The finger has a modular design, which allows to obtain hands with different degrees of freedom and grasping capabilities. Current developments include the implementation of a hand comprising three fingers (opposing thumb, index and middle) and an embedded controller.

Principle of Superposition for Controlling Pinch Motions by Means of Robot Fingers with Soft Tips

This paper analyzes dynamics and control of pinch motions generated by a pair of two multi-degrees-of-freedom robot fingers with soft and deformable tips pinching a rigid object. It is shown firstly that passivity analysis leads to effective design of a feedback control signal that realizes dynamic stable pinching (grasping) even if extra terms of Lagrange’s multipliers arise from holonomic constraints of tight area-contacts between soft finger-tips and surfaces of the rigid object and exert torques and forces on the dynamics. It is shown secondly that a principle of superposition is applicable to design of additional feedback signals for controlling both the posture (rotational angle) and position (some of task coordinates of the mass center) of the object provided that the number of degrees of freedom of each finger is specified for satisfying a condition of stationary resolution on controlled position state variables. The details of feedback signals are presented in the case of a special setup consisting of one 2 DOF finger (corresponding to thumb) and another 3 DOF finger (index finger) like human pinch motion.