AN UNDERACTUATED MECHANICAL HAND PROSTHESYS BY IFToMM ITALY

This paper describes a mechanical underactuated hand, whose design is under patenting. The proposed hand can be used as robot grasping end-effector and, mainly, as a human prosthesis. The proposed underactuated mechanism is based on an adaptive scheme, hence it permits to move five fingers with only one actuator. The actuator is connected to a set of pulleys that operate five tendons. Each tendon will move the phalanxes of a finger. The proposed mechanism permits each finger to adapt its configuration to almost any object shape so that each of the fingers will grasp the object independently on the configuration of the finger itself and independently on the configuration of the other fingers. The tendons are un-extendible so that each finger will grasp an object always with the same force, regardless of object shape. The overall grasping force will be controlled just by adjusting the input actuator torque. This paper also reports preliminary kinematic and dynamic studies aiming to a validation of the feasibility of the proposed design solution. Finally an early experimental prototype is shown

Supernumerary Robotic Fingers as a Therapeutic Device for Hemiparetic Patients

Patients with hemiparesis often have limited functionality in the left or right hand. The standard therapeutic approach requires the patient to attempt to make use of the weak hand even though it is not functionally capable, which can result in feelings of frustration. Furthermore, hemiparetic patients also face challenges in completing many bimanual tasks, for example walker manipulation, that are critical to patients’ independence and quality of life. A prototype therapeutic device with two supernumerary robotic fingers was used to determine if robotic fingers could functionally assist a human in the performance of bimanual tasks by observing the pose of the healthy hand. Specific focus was placed on the identification of a straightforward control routine which would allow a patient to carry out simple manipulation tasks with some intermittent input from a therapist. Part of this routine involved allowing a patient to switch between active and inactive monitoring of hand position, resulting in additional manipulation capabilities. The prototype successfully enabled a test subject to complete various bimanual tasks using the robotic fingers in place of normal hand motions. From these results, it is clear that the device could allow a hemiparetic patient to complete tasks which would previously have been impossible to perform

An Underactuated Multi-finger Grasping Device

In this paper, a mechanical model for an underactuated multi-finger grasping device is presented. The device has single-tendon, three-phalanx fingers, all moved by only one actuator. By means of the model, both the kinematic and dynamical behaviour of the finger itself can be studied. The finger is part of a more complex mechanical system that consists of a four-finger grasping device for robots or a five-finger human hand prosthesis. Some results of both the kinematic and dynamical behaviour are also presented

Adaptive Synergies for the Design and Control of the Pisa/IIT SoftHand

In this paper we introduce the Pisa/IIT SoftHand, a novel robot hand prototype designed with the purpose of being robust and easy to control as an industrial gripper, while exhibiting high grasping versatility and an aspect similar to that of the human hand. In the paper we briefly review the main theoretical tools used to enable such simplification, i.e. the neuroscience-based notion of soft synergies. A discussion of several possible actuation schemes shows that a straightforward implementation of the soft synergy idea in an effective design is not trivial. The approach proposed in this paper, called adaptive synergy, rests on ideas coming from underactuated hand design. A synthesis method to realize a desired set of soft synergies through the principled design of adaptive synergy is discussed. This approach leads to the design of hands accommodating in principle an arbitrary number of soft synergies, as demonstrated in grasping and manipulation simulations and experiments with a prototype. As a particular instance of application of the synthesis method of adaptive synergies, the Pisa/IIT SoftHand is described in detail. The hand has 19 joints, but only uses 1 actuator to activate its adaptive synergy. Of particular relevance in its design is the very soft and safe, yet powerful and extremely robust structure, obtained through the use of innovative articulations and ligaments replacing conventional joint design. The design and implementation of the prototype hand are shown and its effectiveness demonstrated through grasping experiments, reported also in multimedia extensio

Advancing the Underactuated Grasping Capabilities of Single Actuator Prosthetic Hands

The last decade has seen significant advancements in upper limb prosthetics, specifically in the myoelectric control and powered prosthetic hand fields, leading to more active and social lifestyles for the upper limb amputee community. Notwithstanding the improvements in complexity and control of myoelectric prosthetic hands, grasping still remains one of the greatest challenges in robotics. Upper-limb amputees continue to prefer more antiquated body-powered or powered hook terminal devices that are favored for their control simplicity, lightweight and low cost; however, these devices are nominally unsightly and lack in grasp variety. The varying drawbacks of both complex myoelectric and simple body-powered devices have led to low adoption rates for all upper limb prostheses by amputees, which includes 35% pediatric and 23% adult rejection for complex devices and 45% pediatric and 26% adult rejection for body-powered devices [1]. My research focuses on progressing the grasping capabilities of prosthetic hands driven by simple control and a single motor, to combine the dexterous functionality of the more complex hands with the intuitive control of the more simplistic body-powered devices with the goal of helping upper limb amputees return to more active and social lifestyles. Optimization of a prosthetic hand driven by a single actuator requires the optimization of many facets of the hand. This includes optimization of the finger kinematics, underactuated mechanisms, geometry, materials and performance when completing activities of daily living. In my dissertation, I will present chapters dedicated to improving these subsystems of single actuator prosthetic hands to better replicate human hand function from simple control. First, I will present a framework created to optimize precision grasping – which is nominally unstable in underactuated configurations – from a single actuator. I will then present several novel mechanisms that allow a single actuator to map to higher degree of freedom motion and multiple commonly used grasp types. I will then discuss how fingerpad geometry and materials can better grasp acquisition and frictional properties within the hand while also providing a method of fabricating lightweight custom prostheses. Last, I will analyze the results of several human subject testing studies to evaluate the optimized hands performance on activities of daily living and compared to other commercially available prosthesis

Manos Robóticas Antropomórficas: una revisión

This paper presents a review on main topic regarding to anthropomorphic robotic hands developed in the last years, taking into account the more important mechatronics designs submit on the literature, and making a comparison between them. The next chapters deepen on level of anthropomorphism and dexterity in advanced actuated hands and upper limbs prostheses, as well as a brief overview on issues such as grasping, transmission mechanisms, sensory and actuator system, and also a short introduction on under-actuated robotic hands is reported.Este artículo presenta una revisión de los principales desarrollos que se han hecho en los últimos años en manos robóticas antropomórficas. Las primeras secciones tratan temas como el grado de antropomorfismo y de destreza en las manos robóticas más avanzadas, incluyendo una comparación entre ellas. También se abordan temas como la capacidad de agarre de los efectores finales, los mecanismos de trasmisión, el sistema actuador y sensórico, así como una breve introducción al tema de manos robóticas sub-actuadas. Dirección de correspondencia: Carrera 11 # 101-80, Bogotá (Colombia)

Master of Science

thesisAutonomous and teleoperated flying robots capable of perch-and-stare are desirable for reconnaissance missions. Current solutions for perch-and-stare applications utilize various methods to enable aircraft to land on a limited set of surfaces that are typically horizontal or vertical planes. Motivated by the fact that songbirds are able to sleep in trees, without requiring active muscle control to stay perched, the research presented here details a concept that allows for passive perching of rotorcraft on a variety of surfaces. This thesis presents two prototype iterations, where perching is accomplished through the integration of two components: a compliant, underactuated gripping foot and a collapsing leg mechanism that converts aircraft weight into tendon tension in order to passively actuate the foot. This thesis presents the design process and analysis of the mechanisms. Additionally, stability tests were performed on the second prototype, attached to a quadrotor, that detail the versatility of the system and ability of the system to support external moments. The results show promise that it is possible to passively perch a rotorcraft on multiple surfaces and support reasonable environmental disturbances