PERCROScuola Superiore S. Anna1 Detailed Workplan for 2005 Pisa April 11-12, 2005 HAPTEX 2 nd Technical Meeting PERCRO

PERCRO Scuola Superiore S. Anna 1

““Detailed Workplan for 2005”Detailed Workplan for 2005”

Pisa – April 11-12, 2005

HAPTEXHAPTEX22ndnd Technical Meeting Technical Meeting

PERCROPERCRO


Role of Role of PERCROPERCRO in in HAPTEXHAPTEX – Overview – Overview

WP Role of PERCRO

WP1 • Contribution to the System Requirements• Contribution to the definition of the System Architecture

WP2 • Support on the Test Activity of the Haptic Renderer

WP4• Leader of Workpackage• Responsible for the Complete HI Specifications• Design and development of the Force Feedback Device• Responsible for the Complete HI Integration

WP5 • Contribution to the VR System Integration

WP6 • Contribution to Management and Dissemination


Plan of Activities for 2005Plan of Activities for 2005

5 Main Goals:

1. Definition of the Physical Interaction with Virtual Textiles (WP1)

2. Definition of the SW/Logical interface with the Haptic Renderer (WP1)

3. HW Interface (Mechanical & Electrical) with Tactile Actuators (WP4)

4. Specifications of the Complete Haptic Interface (WP4)

5. Preliminary Design of the Force Feedback Device (WP4)


Goal 1Goal 1Definition of the Physical Interaction with Virtual TextilesDefinition of the Physical Interaction with Virtual Textiles

The fabric hangs in air from a stand. The user draws up his fingers to fabric, pinch and rub it using the thumb and index fingertips and stretch it against the stand.

The fabric is wrapped on a soft material (like a pillow). The core of the soft material is fixed in space. The user draws up his hand to the virtual pillow. He can shrink, press, rub interacting with the palmar side of the finger (one or more than one).

The fabric is placed on a rigid wall. Its boundaries are rigidly attached on the wall. The user can press his index and thumb fingertips on the fabric and rub and stretch it.

How the user will haptically interact with the virtual textile?

CASE A CASE B CASE C

EXAMPLES OF POSSIBLE INTERACTIONS


Goal 2Goal 2Definition of the SW/Logical Interface with the Haptic RendererDefinition of the SW/Logical Interface with the Haptic Renderer

• Variables to be transmitted• Minimum refresh rate• Maximum latency• Protocol

Content:

HapticRenderer

KinestheticHaptic Interface

TactileActuators

VREngine

?

?

?

?


Goal 3Goal 3HW HW Interface Interface ((Mechanical & Electrical) with Tactile ActuatorsMechanical & Electrical) with Tactile Actuators

• Weight / Encumbrance of Tactile Actuators• Mechanical Attachment with the Force Feedback Device• Number and Type of Electrical Wires• Allowable Bending Radius of Electrical Wires

Content:


Goal 4Goal 4 Specifications of the Complete Haptic InterfaceSpecifications of the Complete Haptic Interface

• Global Forces on Contact Areas (Force Feedback)• Contact Areas• Number of Independent Force Components• Max Continuous and Peak Force Intensity• Force Accuracy, Resolution and Bandwidth

• Tracked Workspace and Max Speed of Contact Areas

• Tactile Stimulation (Tactile Feedback)• Spatial Resolution• Total number of Tactors per Contact Area• Force Accuracy, Resolution and Bandwidth per Tactor

• External Interface• With the user (limb supporting the device, wearing

requirements etc.)• Electrical & SW interface

• General Constraints• Max Allowable Weight• Allowable Minimal Distance between Fingers

Indicative List of Specifications:


Goal 4Goal 4Specifications of the Complete Haptic InterfaceSpecifications of the Complete Haptic Interface

• Contact Areas (where the forces are exerted?)• Workspace (which is the extent of movements?)• Forces (how many indipendent force components?)

Which haptic interaction?

Good Good

Good

Fair

FairNot suitable

HI configurations defined in the TA


Goal 5Goal 5Preliminary Design of the Force Feedback DevicePreliminary Design of the Force Feedback Device

Configuration A

•2 contact areas•3 independent force components per CA•6 independent actuators

•11 contact areas•1 independent force components per CA•12 independent actuators

New Device 1 New Device 2

HAPTEXSpecs

Refurbishment and adaptation of the Existing

Device

Design from scratch of a new implementation

conceptPast experience (2002)

Past experience (1994)

HAPTEXSpecs

Configuration BPERCRO will develop 2 different HI Device Configurations


Configuration AConfiguration A

Pincher• The Pincher is composed by two identical micro-manipulators.• The bases of the devices are integral with the user’s forearm.• If the bases are fixed in space, the user can perform only the flexion/extension and abduction/adduction of the palm and the flexion-extension of the finger’s articulations. • Global movements of the forearm require an extra device (like an exoskeleton, or a passive gravity balancer).• The dynamic characteristic of the device is excellent (low moving mass).

• The GRAB is composed by two identical macro-manipulators.• The bases of the two manipulators are fixed on the desktop.• The user can move his hands and fingers freely in space within the workspace limits of the two devices.• The dynamic characteristic of the device is good.

PAST EXPERIENCEGRAB


Configuration AConfiguration A

REFURBISHMENT OF EXISTING DEVICE

Activities

to allow the mechanical and electrical integration of the tactile actuators of UNEXE.

• New Dimensioning and Selection of Actuators• Redesign of the Gimbal and of the Links• Analsys of the Routing of the Electrical Wire

General Goal


Configuration BConfiguration B

PAST EXPERIENCE

Hand Exos (1994) • The Hand Exos is composed by four independent exoskeletons, one for each finger (little excluded).

• Each finger exoskeleton has 4 DOFs, 3 of which sensorized and actuated and only 1 sensorized.

• It employs 12 DC iron-less servomotors remotely located on the dorsal side of the palm and in tension tendon unilateral transmissions.

• The measure of the forces is performed by built-in force sensors based on metallic strain gauges.

DrawbacksTests performed on the device have demonstrated that the unilateral mechanical transmissions are critical for a practical use.



DESIGN FROM SCRATCH

Activities

• Analysis of the State of Art

• Architectural Design

• Preliminary Design

• Detailed Design



DESIGN FROM SCRATCH

Analysis of the State of ArtCyber Grasp (Virtual Tecnologies)• 2 coupled force components on the last two phalanxes of all fingers

• 5 DC Motors remotely located in a Fixed Box• Mechanical Transmission with Sheathed Tendons• Mass 453g• Max continous force 12N• Workspace: sphere with radius 1m from actuation

system

• the user feels disturbing forces not correlated to the simulation • high friction cable-sheath (stick-slip)• low stiffness (long tendons)• extra encumbrance of the external fixed box

Drawbacks


Analysis of the State of Art (cont)Analysis of the State of Art (cont)

Rutger Master II-ND(Rutger University)

L. R. P. Force Feedback

Data Glove

• 1 independent force component for each finger, little excluded• 4 pneumatic motors on-board• mass 80g• max force: 16N • min force 0,014N• workspace: sphere with radius 2m from air supply system

• 3 independent force components for each finger, 1 for each phalanx• 14 DC motors remotely located in a fixed box• sheathed cables mechanical transmission• mass of aluminium structure 350g

• the direction of the exerted force is dependent with the finger posture• the device doesn’t allow the complete closure of the hand• low stiffness (compressible fluid)• high friction (due to the air sealing)

• the user feels disturbing forces not correlated to the simulation• high friction cable-sheath (stick-slip)• low stiffness (long tendons)• extra encumbrance of the external fixed box

DrawbacksDrawbacks



DESIGN FROM SCRATCH

Architectural Design

Components Lay-Out

Reference Configuration

• Kinematic Isomorphic with the Physiological one

• Iron-less DC Servomotor

• Actuators located on the dorsal side of the palm

• Bilateral Long Transmissions with in Tension Tendons

• Strain Gauges for the measure of the Exerted Forces

• Class A (not PWM) Current Drivers

All the mechanical components are located on the dorsal side of the hand.

Motors

PositionSensors

ForceSensors

Linkage



DESIGN FROM SCRATCHPreliminary Design

• Identification / Selection of the Remote Center of Rotation Mechanism (RCRM)

• Identification of the Scheme for the Bilateral Tendon Transmission

• Preliminary Performance Evaluation (Stiffness, Inertia, Torque Requirements, ...)

• Selection of the DC Torque Motor and of the Position Sensors

• Preliminary Dimensioning of the Force Sensor

• Preliminary 3D Modeling of the Mechanical Assembly

Activities


Configuration BConfiguration BDESIGN FROM SCRATCH

Detailed Design

• Weight and Encumbrance Reduction• High Density Packaging of Mechanical & Electrical Components:

• Actuators• Sensors (Position, Force)• Links• Wires• Tendon Transmissions• Conditioning & Communication Electronics (embedded in the mechanics)

• Routing & Wiring of the Electrical Cables• Reliability of the Complete Device

Technical Challenges


DeadlinesDeadlines

Goal Title Deadline

1 Definition of the Physical Interaction with Virtual Textiles (WP1)

June 2005

2 Definition of the SW/Logical Interface with the Haptic Renderer (WP1) June 2005

3 HW Interface (Mechanicl & Electrical) with Tactile Actuators (WP4) Oct 2005

4 Specifications of the Complete Haptic Interface (WP4) Nov 2005

5 Preliminary Design of the Force Feedback Device (WP4) Dec 2005

Documents

PERCROScuola Superiore S. Anna1 Detailed Workplan for 2005 Pisa April 11-12, 2005 HAPTEX 2 nd Technical Meeting PERCRO