![Motivation
Model
Experiments
Conclusions
Motivation
Figure: Dextre at the tip of Canadarm2 [1].
Mike Boos Validation of Volumetric Contact Dynamics Models](https://image.slidesharecdn.com/seminar-120305211938-phpapp02/85/MASc-Seminar-Validation-of-Volumetric-Contact-Dynamics-Models-4-320.jpg)
![Motivation
Model
Experiments
Conclusions
Contact Models
28"
36"
Micro Fixture 12"
Point contact models
Electrical
Connectors
Alignment Coarse
Small contact patches only
Sleeve Alignment Bumper
Simple, convex geometries
Alignment
Pins
No rolling resistance,
SPDM
OTCM
spinning friction torque
Battery Worksite
Battery
FEM
Worksite
Too complex for real-time
Figure: ISS battery box [1].
Mike Boos Validation of Volumetric Contact Dynamics Models](https://image.slidesharecdn.com/seminar-120305211938-phpapp02/85/MASc-Seminar-Validation-of-Volumetric-Contact-Dynamics-Models-5-320.jpg)
![Motivation
Volumetric model
Model
Normal forces
Experiments
Friction forces
Conclusions
Volumetric model
fN
kv
Figure: The modified Winkler elastic foundation model [1].
Mike Boos Validation of Volumetric Contact Dynamics Models](https://image.slidesharecdn.com/seminar-120305211938-phpapp02/85/MASc-Seminar-Validation-of-Volumetric-Contact-Dynamics-Models-9-320.jpg)
![Motivation
Volumetric model
Model
Normal forces
Experiments
Friction forces
Conclusions
Volumetric properties
Bi
Kw
s nj
fs,j (s)
ni
fs,i (s)
Contact Surface S
Contact Plate Bj
Figure: The contact surface between two deformable bodies [1].
Volumetric properties
V - volume of interference Js - surface-inertia tensor
n - contact normal Jv - volume-inertia tensor
Mike Boos Validation of Volumetric Contact Dynamics Models](https://image.slidesharecdn.com/seminar-120305211938-phpapp02/85/MASc-Seminar-Validation-of-Volumetric-Contact-Dynamics-Models-10-320.jpg)
![Motivation
Volumetric model
Model
Normal forces
Experiments
Friction forces
Conclusions
Friction
f t Friction force
τ s Spinning friction torque fN
7-parameter model
Bristle stiffness and damping (σo ,
σ1 )
Slip-stick effects (µS , µC , vS ) Contact sites
Dwell-time dependency (τdw )
Figure: Surface asperities
Viscous damping (σ2 ) (‘bristles’) in contact [1].
Mike Boos Validation of Volumetric Contact Dynamics Models](https://image.slidesharecdn.com/seminar-120305211938-phpapp02/85/MASc-Seminar-Validation-of-Volumetric-Contact-Dynamics-Models-13-320.jpg)
![Motivation
Volumetric model
Model
Normal forces
Experiments
Friction forces
Conclusions
The Contensou effect
vC
ωr
C
vB
ωr
Translational friction forces v
A B
tend to ‘cancel out’ as angular vA
ωr ω
velocity increases.
vD
D
ωr
Figure: v << ωr [2]
Mike Boos Validation of Volumetric Contact Dynamics Models](https://image.slidesharecdn.com/seminar-120305211938-phpapp02/85/MASc-Seminar-Validation-of-Volumetric-Contact-Dynamics-Models-14-320.jpg)
![Motivation
Volumetric model
Model
Normal forces
Experiments
Friction forces
Conclusions
The Contensou effect
ωr
vC
C ωr
ωr
Translational friction forces v
vB
tend to ‘cancel out’ as angular vA
A ω B
velocity increases. ωr
vD
D
Figure: v >> ωr [2]
Mike Boos Validation of Volumetric Contact Dynamics Models](https://image.slidesharecdn.com/seminar-120305211938-phpapp02/85/MASc-Seminar-Validation-of-Volumetric-Contact-Dynamics-Models-15-320.jpg)
![Motivation
Volumetric model
Model
Normal forces
Experiments
Friction forces
Conclusions
The Contensou effect
ωr
vC
C ωr
Translational friction forces ωr vB
v
tend to ‘cancel out’ as angular vA
A ω B
velocity increases. ωr
vD
D
Figure: v ωr [2]
Mike Boos Validation of Volumetric Contact Dynamics Models](https://image.slidesharecdn.com/seminar-120305211938-phpapp02/85/MASc-Seminar-Validation-of-Volumetric-Contact-Dynamics-Models-16-320.jpg)
MASc Seminar: Validation of Volumetric Contact Dynamics Models
- 1. Motivation Model Experiments Conclusions Validation of Volumetric Contact Dynamics Models Mike Boos May 11, 2011 Mike Boos Validation of Volumetric Contact Dynamics Models
- 2. Motivation Model Experiments Conclusions Outline 1 Motivation 2 Model Volumetric model Normal forces Friction forces 3 Experiments Normal forces Friction forces Experimental apparatus 4 Conclusions Mike Boos Validation of Volumetric Contact Dynamics Models
- 3. Motivation Model Experiments Conclusions Outline 1 Motivation 2 Model Volumetric model Normal forces Friction forces 3 Experiments Normal forces Friction forces Experimental apparatus 4 Conclusions Mike Boos Validation of Volumetric Contact Dynamics Models
- 4. Motivation Model Experiments Conclusions Motivation Figure: Dextre at the tip of Canadarm2 [1]. Mike Boos Validation of Volumetric Contact Dynamics Models
- 5. Motivation Model Experiments Conclusions Contact Models 28" 36" Micro Fixture 12" Point contact models Electrical Connectors Alignment Coarse Small contact patches only Sleeve Alignment Bumper Simple, convex geometries Alignment Pins No rolling resistance, SPDM OTCM spinning friction torque Battery Worksite Battery FEM Worksite Too complex for real-time Figure: ISS battery box [1]. Mike Boos Validation of Volumetric Contact Dynamics Models
- 6. Motivation Model Experiments Conclusions Contact Models Point contact models Small contact patches only Simple, convex geometries No rolling resistance, spinning friction torque FEM Falling ISS battery box: Too complex for real-time real-time Mike Boos Validation of Volumetric Contact Dynamics Models
- 7. Motivation Model Experiments Conclusions Goals 1 Experimentally validate the volumetric contact dynamics model for hard-on-hard (metal) contact 2 Demonstrate parameter identification for the model Mike Boos Validation of Volumetric Contact Dynamics Models
- 8. Motivation Volumetric model Model Normal forces Experiments Friction forces Conclusions Outline 1 Motivation 2 Model Volumetric model Normal forces Friction forces 3 Experiments Normal forces Friction forces Experimental apparatus 4 Conclusions Mike Boos Validation of Volumetric Contact Dynamics Models
- 9. Motivation Volumetric model Model Normal forces Experiments Friction forces Conclusions Volumetric model fN kv Figure: The modified Winkler elastic foundation model [1]. Mike Boos Validation of Volumetric Contact Dynamics Models
- 10. Motivation Volumetric model Model Normal forces Experiments Friction forces Conclusions Volumetric properties Bi Kw s nj fs,j (s) ni fs,i (s) Contact Surface S Contact Plate Bj Figure: The contact surface between two deformable bodies [1]. Volumetric properties V - volume of interference Js - surface-inertia tensor n - contact normal Jv - volume-inertia tensor Mike Boos Validation of Volumetric Contact Dynamics Models
- 11. Motivation Volumetric model Model Normal forces Experiments Friction forces Conclusions Normal forces V Normal force vcn f n = kv V (1 + avcn )n n S Mike Boos Validation of Volumetric Contact Dynamics Models
- 12. Motivation Volumetric model Model Normal forces Experiments Friction forces Conclusions Rolling resistance V Rolling resistance torque τ r = kv a Js · ω t n ωt S Mike Boos Validation of Volumetric Contact Dynamics Models
- 13. Motivation Volumetric model Model Normal forces Experiments Friction forces Conclusions Friction f t Friction force τ s Spinning friction torque fN 7-parameter model Bristle stiffness and damping (σo , σ1 ) Slip-stick effects (µS , µC , vS ) Contact sites Dwell-time dependency (τdw ) Figure: Surface asperities Viscous damping (σ2 ) (‘bristles’) in contact [1]. Mike Boos Validation of Volumetric Contact Dynamics Models
- 14. Motivation Volumetric model Model Normal forces Experiments Friction forces Conclusions The Contensou effect vC ωr C vB ωr Translational friction forces v A B tend to ‘cancel out’ as angular vA ωr ω velocity increases. vD D ωr Figure: v << ωr [2] Mike Boos Validation of Volumetric Contact Dynamics Models
- 15. Motivation Volumetric model Model Normal forces Experiments Friction forces Conclusions The Contensou effect ωr vC C ωr ωr Translational friction forces v vB tend to ‘cancel out’ as angular vA A ω B velocity increases. ωr vD D Figure: v >> ωr [2] Mike Boos Validation of Volumetric Contact Dynamics Models
- 16. Motivation Volumetric model Model Normal forces Experiments Friction forces Conclusions The Contensou effect ωr vC C ωr Translational friction forces ωr vB v tend to ‘cancel out’ as angular vA A ω B velocity increases. ωr vD D Figure: v ωr [2] Mike Boos Validation of Volumetric Contact Dynamics Models
- 17. Motivation Volumetric model Model Normal forces Experiments Friction forces Conclusions Volumetric contact model Ball-table simulation: real-time Mike Boos Validation of Volumetric Contact Dynamics Models
- 18. Motivation Normal forces Model Friction forces Experiments Experimental apparatus Conclusions Outline 1 Motivation 2 Model Volumetric model Normal forces Friction forces 3 Experiments Normal forces Friction forces Experimental apparatus 4 Conclusions Mike Boos Validation of Volumetric Contact Dynamics Models
- 19. Motivation Normal forces Model Friction forces Experiments Experimental apparatus Conclusions Contact geometries Focus on simple geometric pairs: Cylinder-on-plane Mike Boos Validation of Volumetric Contact Dynamics Models
- 20. Motivation Normal forces Model Friction forces Experiments Experimental apparatus Conclusions Contact geometries Focus on simple geometric pairs: Cylinder-on-plane Sphere-on-plane Mike Boos Validation of Volumetric Contact Dynamics Models
- 21. Motivation Normal forces Model Friction forces Experiments Experimental apparatus Conclusions Normal force experiments Volumetric stiffness Increase force on payload quasi-statically Measure normal forces and displacements (to calculate volume of interference) fN = kv V Mike Boos Validation of Volumetric Contact Dynamics Models
- 22. Motivation Normal forces Model Friction forces Experiments Experimental apparatus Conclusions Normal force experiments Volumetric stiffness Increase force on payload quasi-statically Measure normal forces and displacements (to calculate volume of interference) Damping Drive the payload into contact plate at set velocities fN = kv V (1 + avcn ) Measure forces and displacements over time Mike Boos Validation of Volumetric Contact Dynamics Models
- 23. Motivation Normal forces Model Friction forces Experiments Experimental apparatus Conclusions Translation Static friction and bristle dynamics 1 Begin with payload at rest 2 Slowly increase force until slipping occurs Peak force can be used to estimate µS : fN µS f t t µS Also, σo = δz Mike Boos Validation of Volumetric Contact Dynamics Models
- 24. Motivation Normal forces Model Friction forces Experiments Experimental apparatus Conclusions Translation Coulomb friction and viscous damping Drive payload at different constant velocities f t fN σ2 fN µC ft ≈ fn (µC + σ2 vt ) v t Mike Boos Validation of Volumetric Contact Dynamics Models
- 25. Motivation Normal forces Model Friction forces Experiments Experimental apparatus Conclusions Translation Dwell-time dependency Static friction: Bonds between surfaces form over time when at rest. 1 Drive payload at a constant velocity 2 Bring to a stop for a set period of time 3 Slowly increase force until slipping tpeak − tstop occurs τdw ≈ ln( µµS −µC ) S −µpeak 4 Repeat, increasing the dwell time, until no change in peak force detected between iterations Mike Boos Validation of Volumetric Contact Dynamics Models
- 26. Motivation Normal forces Model Friction forces Experiments Experimental apparatus Conclusions Rotation Repeat translation experiments, rotating instead of translating Compare parameters for translation and rotation Mike Boos Validation of Volumetric Contact Dynamics Models
- 27. Motivation Normal forces Model Friction forces Experiments Experimental apparatus Conclusions Combined translation and rotation Contensou effect 1 Drive at constant tangential velocity with increasing angular velocity 2 Drive at constant angular velocity with increasing tangential velocity 3 Using parameters identified in previous experiments, model the friction forces to compare with observed Contensou effect Mike Boos Validation of Volumetric Contact Dynamics Models
- 28. Motivation Normal forces Model Friction forces Experiments Experimental apparatus Conclusions Normal force configuration Mike Boos Validation of Volumetric Contact Dynamics Models
- 29. Motivation Normal forces Model Friction forces Experiments Experimental apparatus Conclusions Friction configuration Mike Boos Validation of Volumetric Contact Dynamics Models
- 30. Motivation Normal forces Model Friction forces Experiments Experimental apparatus Conclusions Apparatus Mike Boos Validation of Volumetric Contact Dynamics Models
- 31. Motivation Model Experiments Conclusions Outline 1 Motivation 2 Model Volumetric model Normal forces Friction forces 3 Experiments Normal forces Friction forces Experimental apparatus 4 Conclusions Mike Boos Validation of Volumetric Contact Dynamics Models
- 32. Motivation Model Experiments Conclusions Conclusions Volumetric contact dynamics model discussed Experimental procedure developed for parameter identification and validation Design of experimental apparatus Mike Boos Validation of Volumetric Contact Dynamics Models
- 33. Motivation Model Experiments Conclusions References Y. Gonthier. Contact Dynamics Modelling for Robotic Task Simulation. PhD Thesis, University of Waterloo, 2007. Y. Gonthier, J. McPhee, C. Lange. On the Implementation of Coulomb Friction in a Volumetric-Based Model for Contact Dynamics. Proceedings of IDETC’07, 2007. Mike Boos Validation of Volumetric Contact Dynamics Models
- 34. Motivation Model Experiments Conclusions Research supported by Mike Boos Validation of Volumetric Contact Dynamics Models
- 35. Motivation Model Experiments Conclusions Questions Mike Boos Validation of Volumetric Contact Dynamics Models