Umberto Scarcia

The DEXMART hand: Mechatronic design and experimental evaluation of synergy-based control for human-like grasping

This paper summarizes recent activities carried out for the development of an innovative anthropomorphic robotic hand called the DEXMART Hand. The main goal of this research is to face the problems that affect current robotic hands by introducing suitable design solutions aimed at achieving simplification and cost reduction while possibly enhancing robustness and performance. While certain aspects of the DEXMART Hand development have been presented in previous papers, this paper is the first to give a comprehensive description of the final hand version and its use to replicate human-like grasping. In this paper, particular emphasis is placed on the kinematics of the fingers and of the thumb, the wrist architecture, the dimensioning of the actuation system, and the final implementation of the position, force and tactile sensors. The paper focuses also on how these solutions have been integrated into the mechanical structure of this innovative robotic hand to enable precise force and displacement control of the whole system. Another important aspect is the lack of suitable control tools that severely limits the development of robotic hand applications. To address this issue, a new method for the observation of human hand behavior during interaction with common day-to-day objects by means of a 3D computer vision system is presented in this work together with a strategy for mapping human hand postures to the robotic hand. A simple control strategy based on postural synergies has been used to reduce the complexity of the grasp planning problem. As a preliminary evaluation of the DEXMART Hand’s capabilities, this approach has been adopted in this paper to simplify and speed up the transfer of human actions to the robotic hand, showing its effectiveness in reproducing human-like grasping.

A three-fingered cable-driven gripper for underwater applications

In this paper, the design and experimental evaluation of a cable driven robotic gripper for underwater applications is presented. The gripper has three fingers and is characterised by a large workspace if compared with other similar devices reported in literature. Its kinematic configuration allows to execute both parallel and precision grasps on objects with very different dimensions. The gripper has 8 degrees of freedom actuated by only three motors by means of a suitable coupling of the joints obtained through the cable transmission. Moreover, in order to facilitate the execution of complex tasks, special force/torque sensors are mounted on the fingertips. The paper reports the main specifications deriving from the particular tasks in which the gripper is involved, and illustrates the proposed design solutions. Results obtained from real underwater experiments are provided as well, in order to demonstrate the capabilities of the gripper.

Development of robotic hands: The UB hand evolution

This video presents the evolution of the robotic hands, called UB Hands (University of Bologna Hands), developed at the Laboratory of Automation and Robotics of the University of Bologna during more than 25 years of research in this field. Starting from the UB Hand I, the first robot hand prototype developed in our labs, the different design solutions and philosophies that have been followed toward the innovative UB Hand IV, also called DEXMART Hand, recently developed within the DEXMART project are presented. Remarkable characteristics of the UB Hands are also the whole hand manipulation capabilities, the ability of reconstructing the contact forces over the whole hand surface as in the case of the UB Hand II, and the presence of force/tactile sensors as in the UB Hand IV. Moreover, the use of soft covers for the emulation of the human tissue characteristics has been studied, and the adoption of innovative design concepts based on compliant structures has been introduced in the UB Hand III and IV.

Underwater Intervention Robotics: An Outline of the Italian National Project MARIS

The Italian national project MARIS (Marine Robotics for InterventionS) pursues the strategic objective of studying, developing and integrating technologies and methodologies enabling the development of autonomous underwater robotic systems employable for intervention activities, which are becoming progressively more typical for the underwater offshore industry, for search-and-rescue operations, and for underwater scientific missions. Within such an ambitious objective, the project consortium also intends to demonstrate the achievable operational capabilities at a proof-of-concept level, by integrating the results with prototype experimental

Mechatronic Design of a Three-Fingered Gripper for Underwater Applications*

Abstract In this paper, the design and experimental evaluation of a three-fingered robotic gripper for underwater applications is presented. The gripper has some innovative features with respect to other devices known in the literature, concerning in particular the workspace, the kinematic capabilities, and the sensory equipment. The main design specifications are described, deriving from the particular tasks in which the gripper will be involved, and the proposed solutions discussed. Results obtained during real underwater experiments are provided as well, in order to demonstrate the capabilities of the gripper.

Experimental evaluation of a sEMG-based human-robot interface for human-like grasping tasks

In this paper we present a Human-Robot Interface (HRI) to control a robotic hand via myoelectric signals for grasping tasks. The system is composed by the UB Hand IV as robotic device, and by the Cerebro wearable board as acquisition hardware of the signals from surface skin electrodes. The approach implemented for the HRI relies on a pair of antagonistic flexor-extensor muscles that control both the closure and the grasp stiffness of the robotic hand. Humans accomplish a large variety of grasps thanks to precise impedance regulation: the aim of this study is to emulate this capability on a robotic hand using a users muscles driven HRI. Experiments conducted with healty subjects showed a short training time together with high success rate of grasp-related tasks, where the users of the HRI were able to naturally modulate the hands degrees of control by means of forearm muscle contractions. The results show that the system is suitable for further developments for telemanipulation and prosthetic applications.

Autonomous Underwater Intervention: Experimental Results of the MARIS Project

Autonomous underwater vehicles are frequently used for survey missions and monitoring tasks, however, manipulation and intervention tasks are still largely performed with a human in the loop. Employing autonomous vehicles for these tasks has received a growing interest in the last ten years, and few pioneering projects have been funded on this topic. Among these projects, the Italian MARIS project had the goal of developing technologies and methodologies for the use of autonomous underwater vehicle manipulator systems in underwater manipulation and transportation tasks. This work presents the developed control framework, the mechatronic integration, and the projects final experimental results on floating underwater intervention.

A new force/torque sensor for robotic applications based on optoelectronic components.

In this paper, a novel force/torque sensor is presented. The sensor is based on optoelectronic components and therefore its design is relatively simple and reliable. The sensor design make it suitable for the integration in different robotic systems, such as e.g. the fingers of robotic hands. The basic principle and the design of the sensor are described in this paper, along with a specific prototype implemented for underwater applications. Experimental data are presented and discussed to illustrate the main features of the proposed sensor, and its use as an intrinsic tactile sensor is evaluated.

Development of an haptic interface based on twisted string actuators

In this paper, a cable-driven haptic interface able to move in the six-dimensional space, suitable for applications in various robotic scenarios is presented. The device takes advantage of four force-controlled twisted string actuators to generate a linear force along the three Cartesian space dimensions while providing a considerable force-weight ratio and low inertia. The system consists of a frame fixed to the ground, where the twisted string actuation modules are arranged, and by a mechanical interface devoted to the physical connection of the actuators with the forearm of the human operator. This mechanical interface allows to secure the forearm of the user while leaving to her/him the freedom to use the hand to accomplish other tasks, such as teleoperating a robotic gripper. The four twisted string actuators allow to control the three linear DoF of the haptic interface, allowing both Cartesian position and a force regulation. Both the design, the simulation and the preliminary implementation of the haptic interface are presented in this work.

Towards simplicity: On the design of a 2-DOFs wrist mechanism for tendon-driven robotic hands

In this paper, a novel approach for simplifying the design, the prototyping and the assembly of a wrist mechanism with 2 DOFs for anthropomorphic tendon-driven robotic hands is presented. This novel design concept allows a relevant reduction of both the number of parts and their manufacturing complexity, guaranteeing at the same time the decoupling of the fingers and the wrist motion by means of a particular choice of tendons routing. The simplification of the mechanism is achieved with the partial drawback of introducing additional friction forces along the tendons, which are however compensated by the control and do not significantly affect the overall behavior of the hand. The proposed wrist design has been adopted in the development of th UB-Hand IV.