Design of a fully modular and backdrivable dexterous hand

Abstract

This paper presents the mechatronic design of a new anthropomorphic hand. It has been developed in the context of a multidisciplinary project which aims at understanding how humans perform the manipulation of objects in order to replicate grasping and in-hand movements with an artificial hand. This has required the development of a new hand with a high level of both anthropomorphism and dexterity. The hand must exactly replicate the kinematics of the human hand, adding up to 24 degrees of mobility and 20 degrees of freedom, which is a design challenge if a high level of dexterity must be guaranteed. Three key concepts have guided the mechanical design: modularity, backdrivability and mechanical simplicity. A modular approach simplifies the complex hand assembly and permits us to concentrate our efforts on one basic unit which will be replicated throughout the hand. Mechanical simplicity and backdrivability ensure a good natural mechanical behavior, essential for stable control of contact forces. Likewise, a better controllability will enhance the dexterity of the hand. A thorough mechanical design assures backdrivability through the whole mechanism, including actuators and transmission of movement to the joints. Experimental results confirm the validity of the design approach and will open new lines of research into robotic hands.

Force sensing strategy for the backdrivable and dexterous CEA hand

“…Two key concepts have guided the mechanical design: modularity and backdrivability. For an in-depth explanation of the design rationale and a detailed mathematical modeling, information can be found in [16] and [17].…”

“…A detailed calculation of these elements is shown in [17]. All geometric parameters are optimized in order to maximize the force output of the 3 Axes Unit when integrated into the fingers, as well as the range of directions along which forces can be exerted taking into account the restriction given by f 2 , f 3 < 0 (the cables related to the second and third actuators can only pull).…”

Vision and force/torque integration for realtime estimation of fast-moving object under intermittent contacts

“…Although we expect that this will bring us numerous benefits, there are a number of technical issues to be resolved before we demonstrate the practical use of coordinated manipulation with human-like dexterity. From a hardware perspective, there has been much progress in recent years in new designs of complex manipulation systems such as anthropomorphic robotic hands that are capable of highly coordinated manipulation tasks with a large number of degrees of freedom [4][5][6][7]. On the other hand, there is a consensus (see, for example, A Roadmap for US Robotics [1]) that we are still far behind in some key technology areas such as perception, robust high fidelity sensing and planning and control to achieve highly dexterous object manipulation capabilities.…”

On task-decoupling by robust eigenstructure assignment for dexterous manipulation

“…From these emerging needs, roboticists have proposed new mechanical designs and multifingered hands have been developed. Various strategies have been proposed to control these mechanical systems and dexterous manipulation is an active field of research [1]- [3].…”

“…the actuators are synergistically coupled and obeying the minimal intervention principle [10]. To our knowledge, no other works relate task 1 specifications and synergies with the control law for dexterous manipulation. Task decoupling is an issue that has been investigated in several application domains since the 1980s [11] [12], but was not applied in dexterous manipulation.…”