Francesco Chinello

Towards Wearability in Fingertip Haptics: A 3-DoF Wearable Device for Cutaneous Force Feedback

Wearability will significantly increase the use of haptics in everyday life, as has already happened for audio and video technologies. The literature on wearable haptics is mainly focused on vibrotactile stimulation, and only recently, wearable devices conveying richer stimuli, like force vectors, have been proposed. This paper introduces design guidelines for wearable haptics and presents a novel 3-DoF wearable haptic interface able to apply force vectors directly to the fingertip. It consists of two platforms: a static one, placed on the back of the finger, and a mobile one, responsible for applying forces at the finger pad. The structure of the device resembles that of parallel robots, where the fingertip is placed in between the static and the moving platforms. This work presents the design of the wearable display, along with the quasi-static modeling of the relationship between the applied forces and the platforms orientation and displacement. The device can exert up to 1.5 N, with a maximum platform inclination of 30 degree. To validate the device and verify its effectiveness, a curvature discrimination experiment was carried out: employing the wearable device together with a popular haptic interface improved the performance with respect of employing the haptic interface alone.

KUKA Control Toolbox

This article presents an open-source MATLAB toolbox for the motion control of KUKA robot manipulators. The KUKA Control Toolbox (KCT) is a collection of MATLAB functions developed at the Univer sity of Siena. The toolbox, which is compatible with all 6 degrees of freedom (DoF) small and low-payload KUKA robots that use the Eth.RSIXML, runs on a remote computer connected with the KUKA controller via transmission control Protocol/Internet Protocol (TCP/IP). KCT includes more than 40 functions, spanning operations such as forward and inverse kine matics computation, point-to-point joint and Cartesian control, trajectory gen eration, graphical display, three-dimensional (3-D) animation and diagnostics. Applicative examples show the flexibility of KCT and its easy interfacing with other toolboxes and external devices.

Two finger grasping simulation with cutaneous and kinesthetic force feedback

This paper presents an experiment of two finger grasping. The task considered is the peg-in-hole and the simulated force feedback is cutaneous or kinesthetic. The kinesthetic feedback is provided by a commercial haptic device while the cutaneous one is provided by a new haptic display proposed in this work, which allows to render at the fingertip a wide range of contact forces. The device consists of a mobile surface, which interacts with the fingertip, actuated by three wires directly connected to the motors placed on the grounded structure of the display. This work summarizes the design of the proposed display and presents the main relationships which describe its kinematics and dynamics. Results showed that cutaneous feedback exhibits improved performances when compared to visual feedback only.

A three DoFs wearable tactile display for exploration and manipulation of virtual objects

This paper describes a wearable haptic display with small dimensions and low weight, that allows to simulate on the fingertip a wide range of contact forces. The device consists of two platforms: a static one, fixed on the back side of the finger, which supports three actuators and the mechanical instrumented system, and a mobile one, which interacts directly with the fingertip. The platforms are connected by three cables whose lengths and strains are regulated by the motors. Three force sensors, placed on the mobile platform, measure the actual forces applied to the finger. This work summarizes the design of the proposed display and presents a numerical model analysing the relationship between the forces registered at the fingertip and the platforms orientation and displacement. In order to validate the device an experiment of curvature discrimination has been carried out.

Cutaneous haptic feedback to ensure the stability of robotic teleoperation systems

Cutaneous haptic feedback can be used to enhance the performance of robotic teleoperation systems while guaranteeing their safety. Delivering ungrounded cutaneous cues to the human operator conveys in fact information about the forces exerted at the slave side and does not affect the stability of the control loop. In this work we analyze the feasibility, effectiveness, and implications of providing solely cutaneous feedback in robotic teleoperation. We carried out two peg-in-hole experiments, both in a virtual environment and in a real (teleoperated) environment. Two novel 3-degree-of-freedom fingertip cutaneous displays deliver a suitable amount of cutaneous feedback at the thumb and index fingers. Results assessed the feasibility and effectiveness of the proposed approach. Cutaneous feedback was outperformed by full haptic feedback provided by grounded haptic interfaces, but it outperformed conditions providing no force feedback at all. Moreover, cutaneous feedback always kept the system stable, even in the presence of destabilizing factors such as communication delays and hard contacts.

RemoTouch: A system for remote touch experience

This paper presents some preliminary results on RemoTouch, a system allowing to perform experiences of remote touch. The system consists of an avatar equipped with an instrumented glove and a user wearing tactile displays allowing to feel the remote tactile interaction. The main features of RemoTouch are that it is a wearable system and that a human avatar is used to collect remote tactile interaction data. New paradigms of tactile communication can be designed around the RemoTouch system. Two simple experiences are reported to show the potential of the proposed remote touch architecture.

Vibrotactile haptic feedback for human-robot interaction in leader-follower tasks

In this paper we explore a vibrotactile feedback paradigm which allows the human to intuitively interact in human-robot applications. In particular we focus on a haptic bracelet which helps the human to move along trajectories that are feasible for the leader-follower formation tasks. The bracelet consists of three vibrating motors circling the forearm and represents a non invasive way to provide essential information to the human. Experiments performed on a public of 15 subjects revealed the effectiveness of the proposed device.

Soft finger tactile rendering for wearable haptics

This paper introduces a tactile rendering algorithm for wearable cutaneous devices that stimulate the skin through local contact surface modulation. The first step in the algorithm simulates contact between a skin model and virtual objects, and computes the contact surface to be rendered. The accuracy of this surface is maximized by simulating soft skin with its characteristic nonlinear behavior. The second step takes the desired contact surface as input, and computes the device configuration by solving an optimization problem, i.e., minimizing the deviation between the contact surface in the virtual environment and the contact surface rendered by the device. The method is implemented on a thimble-like wearable device.

KCT: a MATLAB toolbox for motion control of KUKA robot manipulators

The Kuka Control Toolbox (KCT) is a collection of MATLAB functions for motion control of KUKA robot manipulators, developed to offer an intuitive and high-level programming interface to the user. The toolbox, which is compatible with all 6 DOF small and low payload KUKA robots that use the Eth.RSIXML, runs on a remote computer connected with the KUKA controller via TCP/IP. KCT includes more than 30 functions, spanning operations such as forward and inverse kinematics computation, point-to-point joint and Cartesian control, trajectory generation, graphical display and diagnostics. The flexibility, ease of use and reliability of the toolbox is demonstrated through two applicative examples.

Design and development of a 3RRS wearable fingertip cutaneous device

Wearable technologies are gaining great popularity in the recent years. The demand for devices that are lightweight and compact challenges researchers to pursue innovative solutions to make existing technologies more portable and wearable. In this paper we present a novel wearable cutaneous fingertip device with 3 degrees of freedom. It is composed of two parallel platforms: the upper body is fixed on the back of the finger, housing three small servo motors, and the mobile end-effector is in contact with the volar surface of the fingertip. The two platforms are connected by three articulated legs, actuated by the motors in order to move the mobile platform toward the users fingertip and re-angle it to simulate contacts with arbitrarily oriented surfaces. Each leg is composed of two rigid links, connected to each other and then to the platforms, according to a RRS (Revolute-Revolute-Spherical) kinematic chain. With respect to other similar cable-driven devices presented in the literature, this device solves the indeterminacy due to the underactuation of the platform. This work presents the main design steps for the development of the wearable display, along with its kinematics, quasi-static modeling, and control. In particular, we analyzed the relationship between device performance and its main geometrical parameters. A perceptual experiment shows that the cutaneous device is able to effectively render different platform configurations.