Model and Control of Tendon Actuated Robots

139 Pages·2007·4.48 MB·English

ALMA MATER STUDIORUM - UNIVERSITA` DEGLI STUDI DI BOLOGNA
DIPARTIMENTO DI ELETTRONICA INFORMATICA E SISTEMISTICA
DOTTORATO DI RICERCA IN AUTOMATICA
E RICERCA OPERATIVA - ING/INF-04
XIX CICLO
PH.D. THESIS
Model and Control of Tendon Actuated Robots
Gianluca Palli
COORDINATORE TUTOR
Prof. ClaudioMelchiorri Prof. ClaudioMelchiorri
A.A. 2004/2006
Author’sWeb Page: http://www-lar.deis.unibo.it/ gpalli/
∼
Author’se-mail: [email protected]
Author’saddress:
DipartimentodiElettronicaInformaticaeSistemistica
AlmaMaterStudiorum-Universita` degliStudi diBologna
VialeRisorgimento2
40136Bologna
Italia
Thisthesiswas writteninLATEX2εonaDebian GNU/LinuxsystemwithGNU Emacs.
Copyright c 2007byGianlucaPalli. Allrightreserved.
(cid:13)
Nopartofthispublication maybereproduced ortransmitted inanyformorbyanymeans,
electronic ormechamical, including photocopy, recording oranyinformation storageand
retrievalsystem,withoutpermission inwritingfromtheauthor.
To mywifeSonia

Abstract
The use of tendons for the transmission of the forces and the movements in robotic de-
vices has been investigated from several researchers all over the world. The interest in
this kind of actuation modality is based on the possibility of optimizing the position of
theactuatorswithrespecttothemovingpartoftherobot,inthereducedweight,highreli-
ability,simplicityin themechanic designand, finally, in the reduced cost of theresulting
kinematicchain.
After a brief discussion about the benefits that the use of tendons can introduce in
the motion control of a robotic device, the design and control aspects of the UB Hand 3
anthropomorphic robotic hand are presented. In particular, the tendon-sheaths transmis-
sion system adopted in the UB Hand 3 is analyzed and the problem of force control and
friction compensationistaken intoaccount.
The implementation of a tendon based antagonistic actuated robotic arm is then in-
vestigated. Withthiskindofactuationmodality,andbyusingtransmissionelementswith
nonlinearforce/compressioncharacteristic,itispossibletoachievesimultaneousstiffness
and position control, improving in this way the safety of the device during the operation
inunknownenvironmentsandinthecaseofinteractionwithotherrobotsorwithhumans.
The problem of modeling and control of this type of robotic devices is then considered
and thestabilityanalysisofproposedcontrollerisreported.
At the end, some tools for the realtime simulation of dynamicsystems are presented.
This realtime simulation environment has been developed with the aim of improving the
reliability of the realtime control applications both for rapid prototyping of controllers
and as teachingtoolsfortheautomaticcontrolcourses.

Acknowledgments
TheauthorthankstheDepartmentofElectronics,ComputerScienceandSystems(DEIS)
oftheFacultyofEngineeroftheUniversityofBolognaforthereceivedsupport,thestaff
of the Laboratory of Automation and Robotics (LAR) and the staff of the Institute of
Robotics and Mechatronics of the German Aerospace Center (DLR) for the help in the
experimentalpartsofthethesis.
A special thank to professor Claudio Melchiorri, the author is grateful to him for the
patienceand theencouragementshownduringtheseyears.

Contents
1 Introduction 1
2 The UBHand3 Project 5
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2 Architectureand KinematicsoftheHand . . . . . . . . . . . . . . . . . 7
2.2.1 MechanicalStructure oftheHand . . . . . . . . . . . . . . . . . 7
2.2.2 FingerKinematics . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.2.3 ConfigurationoftheTendons . . . . . . . . . . . . . . . . . . . . 11
2.3 FingerControl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.4 Sensory Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.5 ActuationModule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.6 TheUBHand 3RealtimeControlSystem . . . . . . . . . . . . . . . . . 17
2.7 ExperimentalActivities . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.8 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3 Model andControl ofTendon-Sheath TransmissionSystems 25
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.2 Tendon-Sheath TransmissionCharacteristic . . . . . . . . . . . . . . . . 26
3.3 TendonDynamicModel . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.4 ExperimentalResults . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.5 The‘Three-Mass’Model . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.5.1 ValidationoftheThree-MassModel . . . . . . . . . . . . . . . . 34
3.5.2 GeometricProperties oftheModel . . . . . . . . . . . . . . . . . 35
3.6 TendonTransmissionControl . . . . . . . . . . . . . . . . . . . . . . . . 37
3.6.1 FrictionCompensation . . . . . . . . . . . . . . . . . . . . . . . 38
3.6.2 OptimalControllerDesign . . . . . . . . . . . . . . . . . . . . . 39
3.7 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4 AntagonisticActuated Robots 43
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
4.2 DynamicModelofRobotswithAntagonisticActuated Joints . . . . . . . 44
4.3 StaticFeedback Linearization . . . . . . . . . . . . . . . . . . . . . . . . 47
4.4 ControlStrategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.5 Properties oftheTransmissionElements . . . . . . . . . . . . . . . . . . 50
4.5.1 QuadraticForce-Displacement TransmissionElements . . . . . . 51
4.5.2 ExponentialForce-DisplacementTransmissionElements . . . . . 52
4.6 SimulationoftheTwo-LinkAntagonisticActuatedArm . . . . . . . . . 53
ii Contents
4.7 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
5 The DLR’s AntagonisticActuated Joint 55
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
5.2 Characterization oftheTransmissionElements . . . . . . . . . . . . . . 56
5.3 System Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
5.3.1 StaticResponse . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
5.3.2 DynamicResponse . . . . . . . . . . . . . . . . . . . . . . . . . 61
5.4 Actuator-LevelStiffness/PositionControl . . . . . . . . . . . . . . . . . 63
5.4.1 Non-BackdrivableActuators . . . . . . . . . . . . . . . . . . . . 63
5.4.2 BackdrivableActuators . . . . . . . . . . . . . . . . . . . . . . . 64
5.5 Feedback Linearization . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
5.5.1 StaticFeedback Linearization . . . . . . . . . . . . . . . . . . . 70
5.5.2 DynamicFeedback Linearization . . . . . . . . . . . . . . . . . 75
5.6 Identification oftheTransmissionElementParameters . . . . . . . . . . 78
5.6.1 OfflineIdentificationProcedure . . . . . . . . . . . . . . . . . . 78
5.6.2 OnlineIdentification Algorithm . . . . . . . . . . . . . . . . . . 80
5.7 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
6 Robots Feedback Linearization Control Based on Joint Position Measure-
ments 85
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
6.2 DynamicsofRoboticManipulators . . . . . . . . . . . . . . . . . . . . . 86
6.3 Feedback LinearizationviaFiltered Velocity . . . . . . . . . . . . . . . . 86
6.4 StabilityofFeedback LinearizationBased on VelocityEstimation . . . . 88
6.4.1 LyapunovFunctionCandidate . . . . . . . . . . . . . . . . . . . 88
6.4.2 TimeDerivativeoftheLyapunovFunctionCandidate . . . . . . . 90
6.4.3 Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
6.5 Case Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
6.6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
7 RealtimeSimulation 97
7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
7.2 RealtimeSimulationofDynamicSystems . . . . . . . . . . . . . . . . . 99
7.3 TheCOMEDIRealtimeSimulationDriver . . . . . . . . . . . . . . . . . 101
7.4 TheInverted Pendulum . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
7.4.1 TheControlSystem . . . . . . . . . . . . . . . . . . . . . . . . 102
7.4.2 TheCOMEDIDriveroftheRotary Inverted Pendulum . . . . . . 103
7.4.3 ExperimentalResults . . . . . . . . . . . . . . . . . . . . . . . . 105
7.5 TheTendon-Sheath LumpedParameterModel . . . . . . . . . . . . . . . 107
7.5.1 TheControlSystem . . . . . . . . . . . . . . . . . . . . . . . . 108
7.5.2 TheCOMEDIDriveroftheTendon-Sheath System . . . . . . . . 108
7.5.3 ExperimentalResults . . . . . . . . . . . . . . . . . . . . . . . . 110