Giuseppe Maria Prisco

A virtual environment with haptic feedback for the treatment of motor dexterity disabilities

We present an immersive virtual environment (VE) including visual, auditory and haptic feedbacks, which has been designed specifically to help to recover or improve the motor dexterity of the arm and hand in patients affected by disorders of motor coordination. The realization of an effective haptic feedback on the human arm and hand is the most critical issue for such application. Innovative approaches have been followed for the monitoring of upper limb movements; the replication of forces on the human hand, the real time simulation of interactions between user upper limb and virtual objects, including the simulation of stable grasps; and the accurate synchronization of the various sensory feedbacks. The rehabilitation exercises, which have already been implemented and tested on healthy subjects are described. The major technical solutions adopted are discussed.

HI2: a two-degrees-of-freedom planar highly isotropic haptic interface for the desktop

Haptic interfaces which fit on the desktop and provide a cursor control with 2D position convey additive feel sensations to the user in GUI and allow to enhance the efficiency of the human-computer interaction for both single user and collaborative applications. The merit of such devices is determined by the adaptability of the handle to different tasks/users, the ergonomics of the 2D workspace, the overall compactness of the device with respect to the usable workspace and the quality of the force feedback. A novel device has been designed along these guidelines. A new tendon-driven 5-bar mechanism is used to improve the isotropy of the kinematic performance over the workspace and the maximum generated force while reducing the device encumbrance. The present paper illustrates the kinematic and mechanical design of the device and reports the specifications achieved by the CAD model evaluation.

Design of an Anthropomorphic Haptic Interface for the Human Arm

In this paper, methods and technical issues dealing with the design of an anthropomorphic haptic interface for the upper limb are presented. The device features seven rotational joints whose axes are aligned with the user arm degrees of freedom (d.o.f.) in order to fully preserve the freedom of movement of the human arm. Its links adhere just to the external side of the user arm, without fully wrapping it. The interface can apply forces and torques at the level of the medium part of the arm, forearm and palm of the user. Highly intuitive operation, universal applicability, large workspace and the possibility of being used together with an hand force feedback system, are the most remarkable consequences of its coherent anthropomorphic design. The system requirements and the design choices are discussed; the innovative mechanical solutions are described.

Experimental approach to virtual surfaces exploration exploiting an arm exoskeleton as haptic interface

This paper deals with the employment of an Arm Exoskeleton as Haptic Interface in order to realize the simplest non trivial kind of force-based interaction which can help Virtual Environments (VE) operators in the completion of exploratory tasks i.e. the interaction of the operator hand with rigid bodies whose position in the VE is fixed. Our interest was to record operators behaviors and feelings and to determine the set of interactions which can be reproduced in a satisfactory way with our system. The experimental results show the influence of system sampling time and force generation model on the realism of contacting and following virtual surfaces.

Preliminary considerations on the design of controllers for haptic interfaces

In this paper the design of controllers for haptic interfaces is discussed. A general methodology to model and design such kind of controllers is presented. Some useful tools for the analysis of stability and performance of haptic interfaces interacting with virtual environments are introduced. The design of a torque controller for a joint of an electrically actuated, tendon driven haptic interface is analyzed as an example.

Hall-effect sensor positional transducer

This paper presents the usage of Hall-Effect sensors for the creation of a low cost, zero friction, minimally invasive precise positional sensor. Hall-Effect sensors are generally being used for revealing the speed of geared-wheels as well as the angular position of wheels having an array of magnets mounted on. In most cases the Hall-Effect sensor have only been used as threshold sensing devices for revealing the presence of magnetic field.

Haptic control of the hand force feedback system

The Hand Force Feedback System is an anthropomorphic haptic interface for the replication of the forces arising during grasping and fine manipulation operations. It is composed of four independent finger dorsal exoskeletons which wrap up four fingers of the human hand (the little finger is excluded). Each finger possesses three electrically actuated DOF placed in correspondence with the human finger flexion axes and a passive DOF allowing finger abduction movements.

Motion Control of Tendon Driven Robotic Fingers Actuated with DC Torque Motors: Analysis and Experiments

This paper deals with the joint position control of a robotic finger designed to test the force feedback performance of an hand controller. The robotic finger is actuated with 3 DC motors located on the base link, which drive the joints by means of bidirectional cable transmissions. The focus of the work is on the analisys of the influence of the elastic cable transmission on the robot dynamics and control. Experimental data are presented to characterize the system behaviour and verify the performance of different control laws. Guidelines for the design of robotic joints actuatated with cables and DC motors are deduced.