Anthropomorphic robot hand design based on dual-mode twisting actuation

Abstract

In this study, an anthropomorphic robot hand design is newly presented by adopting two novel actuation principles, which are called dual-mode twisting actuation, EM joint locking mechanism. The robot hand is designed for the prosthetic use, so its design considerations are based on the requirements of the endusers of the commercial prosthesis. First of all, designing a light-weight and high-speed robot hand with large grasping force is still an unsolved problem. Motivated by the design challenge, this paper is devoted to proposing a design in which speedy motion and large grasping forces are both available, depending on the operational modes. For instance, the output force of a robot finger may not be necessarily large when it moves fast. The robot finger could move slowly if large force is needed. To implement this idea, we propose a new type of power transmission, referred to as dual-mode actuation with a passive clutch mechanism. To propose the design guidelines, the design parameters are derived analytically. Based on these results, a prototype of the robot finger is developed. Through experiments, the effectiveness of the proposed method is demonstrated. Second, the dexterity of the robot hand plays an important role to grasp various objects stably. The usage of a number of the actuators may lead bulky size and heavy weight or weak grasping force of the robot hand. Therefore, EM joint locking mechanism is also proposed to achieve highly dexterous motion without losing performances. This mechanism allows individual operation of each joint of the robot hand by joint locking mechanism, which implies that the enlarged workspace and various postures are available. Finally, an anthropomorphic robot hand for prosthetic applications is developed based on three proposed actuation mechanisms, which has similar performances such as weight, size, and speed to human hands. To verify the performance of the developed robot hand, the fingertip force and bending speed are...