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MAGISTER-P: A 6 URS MAGISTER-P: A 6 URS

Parallel Haptic Device with Open Parallel Haptic Device with Open Control ArchitectureControl Architecture

J. M. SabaterJ. M. Sabater

Miguel Hernández UniversityMiguel Hernández University

Elche, Alicante (Spain)Elche, Alicante (Spain)

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IntroductionIntroduction

Definitions:Definitions:Haptic Display: Haptic Display: A device configured to provide haptic

information to a human is called a haptic display.

Impedance Display.- Impedance Display.- A mechanical device which is configured to render a commanded force while providing a measurement of its position and/or velocity.

Admittance Display.- Admittance Display.- A device configured to track a commanded position or velocity while providing a measurement of force is called an admittance display.

Parallel Platform:Parallel Platform: 6 URS Parallel-Platform: 6 URS Parallel-Platform: Parallel platform whose kinematics

chains are composed by a Universal joint, an articulated parallelogram with a Rotational driven joint, and a Spherical joint.

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Parallel Platforms as haptic devicesParallel Platforms as haptic devices

Advantages:Advantages:Low InertiaLow InertiaHigh stiffness High stiffness Low friction Low friction Gravitationnal counterbalancing Gravitationnal counterbalancing High ratio load/power High ratio load/power work as admittance work as admittanceEasy constructionEasy construction

Disadvantages:Disadvantages:Small workspaceSmall workspaceDifficult controlDifficult controlNumerical dinamic modelNumerical dinamic modelDifficult real-time implementationDifficult real-time implementation

transparency

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Features:

• 6 dof with large workspace.

• Low friction and sensed inertia.

• Open control architecture with C-interface

• Cable transmission without gears.•Transmission rate= 13

• High bandwidth

•Work Modes.

• As Impedance Display

• As Admittance Display

• Aluminium structure with low weight.

• Hardware architecture• Pc controlled multi-axis board

• DC motors

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Theoretical Frame for kinematics algorithmsTheoretical Frame for kinematics algorithms

Geometrical Model

Multibody Theory: Constraint Vector

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Inverse KinematicsInverse Kinematics

Geometrical Solution: Geometrical Solution: The movement of the device is defined by the time variation of C angle between the even and odd links.

A reference system must be assigned to each link.

Auxiliar reference system:

Geometrical Model

2..0,

0

)2/3/)1*2cos((

)2/3/)1*2cos((

1

1

1

iir

ir

s joystick

joystickBn

2..0,

0

)2/3/)*2cos((

)2/3/)*2cos((

0

0

0

iir

ir

s base

baseAn

ABn

ABnnz r

ru

Annz

Annzn

xsu

suu

0

0

BnBn

ABn ssArr 0111

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Inverse Kinematics (ii)Inverse Kinematics (ii)

Even links reference system:

Odd links reference system:

are obtained by a rotation of around vector

are obtained rotating the vector around

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Forward KinematicsForward Kinematics

Multibody theory:Multibody theory:Constraint vector of a 6 URS parallel platformConstraint vector of a 6 URS parallel platform

Newton-Raphson methodNewton-Raphson method

0,,

191

x

P

D

K

q

tCq

q

tq

tqq

jj

q,

qqq

jjj

1

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Simulations of an Impedance DisplaySimulations of an Impedance Display

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MAGISTER-P: Control ModesMAGISTER-P: Control Modes

Open loop:Open loop:

Position loop:Position loop:

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Force - Position experimentForce - Position experiment

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THANKS FOR YOUR ATTENTIONTHANKS FOR YOUR ATTENTION