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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
PERCRO Scuola Superiore S. Anna 2
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
PERCRO Scuola Superiore S. Anna 3
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)
PERCRO Scuola Superiore S. Anna 4
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
PERCRO Scuola Superiore S. Anna 5
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
?
?
?
?
PERCRO Scuola Superiore S. Anna 6
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:
PERCRO Scuola Superiore S. Anna 7
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:
PERCRO Scuola Superiore S. Anna 8
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
PERCRO Scuola Superiore S. Anna 9
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
PERCRO Scuola Superiore S. Anna 10
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
PERCRO Scuola Superiore S. Anna 11
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
PERCRO Scuola Superiore S. Anna 12
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.
PERCRO Scuola Superiore S. Anna 13
Configuration BConfiguration B
DESIGN FROM SCRATCH
Activities
• Analysis of the State of Art
• Architectural Design
• Preliminary Design
• Detailed Design
PERCRO Scuola Superiore S. Anna 14
Configuration BConfiguration B
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
PERCRO Scuola Superiore S. Anna 15
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
PERCRO Scuola Superiore S. Anna 16
Configuration BConfiguration B
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
PERCRO Scuola Superiore S. Anna 17
Configuration BConfiguration B
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
PERCRO Scuola Superiore S. Anna 18
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
PERCRO Scuola Superiore S. Anna 19
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