Abstract
This paper presents an adaptive actuation mechanism that can be employed for the development of anthropomorphic, dexterous robot hands. The tendon-driven actuation mechanism achieves both flexion/extension and adduction/abduction on the finger's metacarpophalangeal joint using two actuators. Moment arm pulleys are employed to drive the tendon laterally and achieve a simultaneous execution of abduction and flexion motion. Particular emphasis has been given to the modeling and analysis of the actuation mechanism. More specifically, the analysis determines specific values for the design parameters for desired abduction angles. Also, a model for spatial motion is provided that relates the actuation modes with the finger motions. A static balance analysis is performed for the computation of the tendon force at each joint. A model is employed for the computation of the stiffness of the rotational flexure joints. The proposed mechanism has been designed and fabricated with the hybrid deposition manufacturing technique. The efficiency of the mechanism has been validated with experiments that include the assessment of the role of friction, the computation of the reachable workspace, the assessment of the force exertion capabilities, the demonstration of the feasible motions, and the evaluation of the grasping and manipulation capabilities. An anthropomorphic robot hand equipped with the proposed actuation mechanism was also fabricated to evaluate its performance. The proposed mechanism facilitates the collaboration of actuators to increase the exerted forces, improving hand dexterity and allowing the execution of dexterous manipulation tasks.
Highlights
The fields of robot grasping and dexterous manipulation have received increased attention over the last years, as robots have already started to interact with their surroundings and assist humans in the execution of dexterous tasks
The human thumb’s metacarpophalangeal joint (MCP) joint along with the trapeziometacarpal and interphalangeal joints are responsible for opposition, which is the most significant motion that contributes to the dexterity of human hand (Kapandji, 1974; Nanayakkara et al, 2017)
We assess the effect of friction and we compare the experimental results with the model of the proposed adaptive finger
Summary
The fields of robot grasping and dexterous manipulation have received increased attention over the last years, as robots have already started to interact with their surroundings and assist humans in the execution of dexterous tasks. One of the most important joints in the human hand is the metacarpophalangeal joint (MCP), which allows the fingers to execute both adduction/abduction and flexion/extension motions, increasing the dexterity of the overall system. The goal of this work is to enhance the robotic finger’s performance in order to facilitate the execution of various grasping and in-hand manipulation tasks by employing less actuators without compromising dexterity, as discussed in (Bicchi, 2000). To this end, we propose a versatile, tendondriven actuation mechanism for anthropomorphic fingers. It is to be noted that the proposed mechanism can be used in other applications (e.g., development of a bio-inspired shoulder)
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