Albu Schaeffer DLR hand

Click here to load reader

download Albu Schaeffer DLR hand

of 51

  • date post

    18-Jan-2016
  • Category

    Documents

  • view

    10
  • download

    3

Embed Size (px)

description

DLR hand, development and control

Transcript of Albu Schaeffer DLR hand

  • Safe Physical Human-Robot Interaction

    Alin Albu-Schffer

    DLR German Aerospace CenterInstitute of Robotics and Mechatronics

  • 2Robots designed to work in human environments

    LWR I (1992)

    LWR II real (1999)

    LWR III real (2002)

    LWR II virtual (1998) LWR III virtual (2000)

    Extreme light-weight arms and hands with 1:1 load-weight ratio mobile manipulation interaction with unknown environments

    KINEMEDIC (2005)

  • 3

  • 4

  • 5Placing of Pedicle Screws

  • 6Experimental Setup with LBR II

    RobotLinear guides with

    marker arrays

    Registrationof vertebra

    Navigationsystem

    Linear guides withmarker arrays

  • 7ROKVISS

    ~15 msdelay

  • 8

  • 9Tele-Maintenance

    Oberpfaffenhofen Space

    Force-Feedback: min. 6 DoF

  • 10

    Affordable, remotely controlled operations in space with mobile (freeflying)robonauts forServicing

    andExploration

    Our Vision

  • 11

    Virtual Product Design: Assembly Scenarios

    DLR LWRas 6-DOF HapticInterface

  • 12

    User Safety Concepts

    intrinsically safe robot design redundant, error detecting electronics redundant sensors dead-man-switch, range check for measurements/commands, robust, passivity based control algorithms collision detection/reaction with joint torque sensors direct control/limitation of exerted forces and torques soft robotics compliance control collision avoidance with redundant kinematics

    collision detection and reaction

    planningcontrolcollision avoidance

    failure detection Hardware

  • 13

    Light-Weight Design

    47 Axes

    4Weight< 10 kg4Payload: 3 kg

    DLR medical robot

    47 Axes

    4Weight: 13.5 kg4Payload: 13.5 kg

    DLR light-weight robot

  • 14

    Measurement torque sensor vibration damping

    Vibration Damping

    Light-weight higher joint compliance vibrations

  • 15

    Joint Flexibility a Feature, not a Drawback?

    YES, for compliance control:Safe interaction with humansManipulation in unknown environmentsHaptics

    (Khatib Lab, Stanford Univ.)

    (Bicchi Lab, Univ. of Pisa)

  • 16

    Every motor used in bidirectional mode

    4 progressive elastic elements per joint

    direct drive to prevent gear side-effects

    tendon-driven

    motor unitminiaturisableto 28mm

    at least 30N at fingertip

    Antagonistic test joint setup

  • 17

    Passively yielding joints

    F rubber balls have progressive spring

    properties with nearly exponential characteristics

    the force with which the balls are squeezed determines the stiffness of the box

    adaptable characteristics through number and diameter of balls

  • 18

    Design Overview

  • 19

    Mechatronic Joint Design

    (redundant)

    Additionally: force-torquesensor at the wrist

  • 20

    User Safety Concepts

    intrinsically safe robot design redundant, error detecting electronics redundant sensors dead-man-switch, range check for measurements/commands, robust, passivity based control algorithms collision detection/reaction with joint torque sensors direct control/limitation of exerted forces and torques soft robotics compliance control collision avoidance with redundant kinematics

    collision detection and reaction

    planningcontrolcollision avoidance

    failure detection Hardware

  • 21

    Strategy

    Goals:

    KeyTechnology:

    StartingPoint:

    Controlapproach:

    Programmablestiffness

    (Soft Robotics)

    Movementaccuracy

    Safe human-robotinteraction

    Joint torquesensor

    Position control withactive

    vibration damping

    Light-weight robotwith elastic joints

  • 22

    Flexible Joint Robot

    State vector:f

    x{

    xdext

  • 23

    Strategy

    Goals:

    KeyTechnology:

    StartingPoint:

    Controlapproach:

    Programmablestiffness

    (Soft Robotics)

    Movementaccuracy

    Safe human-robotinteraction

    Joint torquesensor

    Position control withactive

    vibration damping

    Light-weight robotwith elastic joints

  • 24

    Position Control with Full State Feedback

    4global asymptotically stable (Lyapunov-Analysis) 4passive => robust with respect to parameter uncertainties

    q

    Passive Environmentext

    ,

    Passively controlled actuator 1 Passive rigidrobot dynamics

    Control

    Control

    Model error may cause performance degradationbut not in instability

  • 25

    Passivity

    - Power

    >t T dttytu0 )()()()( tytuT

    0>

    u(t) y(t)dynamical

    system

    System is passive, if

    The energy which can be extracted from the system is bounded

  • 26

  • 27

    User Safety Concepts

    intrinsically safe robot design redundant, error detecting electronics redundant sensors dead-man-switch, range check for measurements/commands, robust, passivity based control algorithms collision detection/reaction with joint torque sensors direct control/limitation of exerted forces and torques soft robotics compliance control collision avoidance with redundant kinematics

    collision detection and reaction

    planningcontrolcollision avoidance

    failure detection Hardware

  • 28

    Quantization of Severity of Impact Injury

    No standards for robotics

    Some borrowed indicesHead Head Injury Criterion - HIC (car crash tests) Maximum Impact Power Maximum Mean Strain Criterion Vienna Institute Index, Effective Displacement

    Index, Revised Brain Model

    mean acceleration

    !?

  • 29

    Collision Detectionf

    x{

    xdext measured signals:

    collision torqueobservable:

    gearbox friction torque / actuator failure

    computed signals:

  • 30

    Observer Implementation

    - generalized momentum

    Linear resulting observer dynamics:

    Ideal situation (no noise)

    (De Luca et. al., 2005)

  • 31

    Reaction Strategies

    strategy 1: stopping the trajectory

    strategy 2: gravity compensated torque mode

    strategy 3: impedance control mode using

    strategy 4: admittance control mode using

  • 32

    Impact Tests

  • 33

    Results on Balloon Impact

    4 residual & velocity on joint 4 for different reaction strategies

    impact at 10/s with coordinated joint motion

    no reaction

  • 34

    Results on Balloon Impact (contd)

    residual & velocity on joint 4 for different reaction strategies

    impact at 100/s with coordinated joint motion

  • 35

    Results on Dummy Head Impact

    approaching at 30/s with each joint residual gains = diag{25}

    joint 1

    2 ms

    joint torque

    observer

    0/1 detection

    acceleration

    HIC < 400

    HIC approaches critical value at 70/s

  • 36

    Strategy

    Goals:

    KeyTechnology:

    StartingPoint:

    Controlapproach:

    Programmablestiffness

    (Soft Robotics)

    Movementaccuracy

    Safe human-robotinteraction

    Joint torquesensor

    Position control withactive

    vibration damping

    Light-weight robotwith elastic joints

  • 37

    Cartesian Stiffness Control

    f

    x{xd

    ___f xd

    Kk

    Dk

    M

  • 38

    Jointtask

    0.33ms

    Slow Cart. Task

    (6-10ms)

    Fast Cart. Task (1ms)

    Cartesian Compliant Behavior

    Impedance controlStiffness controlAdmittance control

    Force Controller

    Inverse kinematics forredundant, nonholonomic

    systems

    Projection ofstiffness & damping:

    Cartesian to jointsnull-space to joints

    Cartesianstiffness & damping

    matrices

    Variable gains for joint stiffness control& vibration damping

    Robot dynamics

    Joint space

    Operational space

    Desired Torquecomputation

    Positioncontrol

    Torquecontrol

    Impedancecontrol

    1ms bus

    Directkinematics

    Jacobian

    k=max k=0Jointtask

    0.33ms

    Slow CartesianTask(6ms)

    Fast Cart. Task (1ms)

    Cartesian Compliant Behavior

    Impedance controlStiffness controlAdmittance control

    Force Controller

    Inverse kinematics forredundant robots

    Projection ofstiffness & damping:

    Cartesian to jointsnull-space to joints

    Cartesianstiffness & damping

    matrices

    Variable gains for joint stiffness control& vibration damping

    Robot dynamics

    Joint space

    Operational space

    Desired Torquecomputation

    Positioncontrol

    Torquecontrol

    Impedancecontrol

    1ms bus

    Directkinematics

    Jacobian

    k=max k=0State vector:

    ,,,

  • 39

    Application: Piston Insertion

  • 40

    Jointtask

    0.33ms

    Slow Cart. Task

    (6-10ms)

    Fast Cart. Task (1ms)

    Cartesian Compliant Behavior

    Impedance controlStiffness controlAdmittance control

    Force Controller

    Inverse kinematics forredundant, nonholonomic

    systems

    Projection ofstiffness & damping:

    Cartesian to jointsnull-space to joints

    Cartesianstiffness & damping

    matrices

    Variable gains for joint stiffness control& vibration damping

    Robot dynamics

    Joint space

    Operational space

    Desired Torquecomputation

    Positioncontrol

    Torquecontrol

    Impedancecontrol

    1ms bus

    Directkinematics

    Jacobian

    k=max k=0Jointtask

    0.33ms

    Slow Cartesi