robot motion control during abrupt switchingsbetween...
Post on 01-Mar-2021
3 Views
Preview:
TRANSCRIPT
1
Torsten Kroeger 1/28 Stanford University
Robot Motion Control During Abrupt
Switchings Between Manipulation Primitives
Torsten Kroeger
Artificial Intelligence Laboratory
Department of Computer Science
Stanford University, USA
Bernd Finkemeyer
KUKA Laboratories GmbH
Augsburg, Germany
Torsten Kroeger 2/28 Stanford University
Acknowledgement
Institut für Robotik und Prozessinformatik, Prof. Wahl
Technische Universität Braunschweig, Germany
This research has mainly been conducted at
2
Torsten Kroeger 3/28 Stanford University
Sensor integration and sensor-based control at multiple levels
is key for the future advancement of robotic systems.
Introduction and Motivation
www.omron.com � www.jr3.com � www.theimagingsource.com � www.sick.com � ww.robotic.dlr.de � www.kuka.com � www.honda.com � www.activerobots.com � www.kinemedic.de
Torsten Kroeger 4/28 Stanford University
• In general, we distinguish between:
1. Trajectory-following motions
2. Sensor-guided motions (sensors in the feedback loops)
- Force/torque control
- Visual servo control
- Distance control
- 9
• In real-world robot applications, systems need to switch between
controllers at unforeseen instants.
• The theoretical tool for such switchings is hybrid switched-
system control.
• How does the real world look like?
Introduction and Motivation
3
Torsten Kroeger 5/28 Stanford UniversityICRA 2004
Torsten Kroeger 6/28 Stanford UniversityICAR 2003
4
Torsten Kroeger 7/28 Stanford UniversityAdvanced Robotics 2005
Torsten Kroeger 8/28 Stanford University
5
Torsten Kroeger 9/28 Stanford UniversityAdvanced Robotics 2005
Torsten Kroeger 10/28 Stanford University
Switching from One MP to Another
• Controllers cannot take over in any situation, e.g.,
- no valid sensor signal,
- force control without contact,
- sudden changes of the environment,
- sensor malfunctions, or
- switching to a controller yields heavy jerk.
• Many compliant motion tasks require instantaneous switchings
from one controller to another in order to achieve stability.
• Requirement: Autonomous switchings at the lowest possible
control level!
• Motion specification by Manipulation Primitives (MPs).
• This framework bases on
[Mason’81, Bruyninckx’96, Finkemeyer’02, Milighetti’05, Zieliñski‘10]
and specifies sensor-guided and sensor-guarded robot motions.
6
Torsten Kroeger 11/28 Stanford University
The Adaptive Selection Matrix
Po
sitio
n
Ve
locity
Dis
tan
ce
Fo
rce
/To
rqu
e
Fu
rth
er
ϕy
ϕz
ϕx
z
y
x
dof 01
2level
device
ϕy
dofP
ositio
n
Ve
locity
Dis
tan
ce
Fo
rce
/To
rqu
e
Fu
rth
er
ϕz
ϕx
z
y
x
device
Adaptive selection matrixClassical selection matrix
An example: Level 0 Level 1 Level 2
‘Force in z-Direction‘ Force Vision Velocity
Torsten Kroeger 12/28 Stanford University
Task Space Control Scheme
7
Torsten Kroeger 13/28 Stanford University
• Hybrid switched-control (simplified for one DOF)
Control Scheme
Torsten Kroeger 14/28 Stanford University
On-Line Trajectory Generation
www.reflexxes.com
Target-position-based on-line trajectory generation.
8
Torsten Kroeger 15/28 Stanford UniversityTarget-position-based on-line trajectory generation.
On-Line Trajectory Generation
www.reflexxes.com
Torsten Kroeger 16/28 Stanford University
On-Line Trajectory Generation
www.reflexxes.com
Target-velocity-based on-line trajectory generation.
9
Torsten Kroeger 17/28 Stanford UniversityTarget-velocity-based on-line trajectory generation.
On-Line Trajectory Generation
www.reflexxes.com
Torsten Kroeger 18/28 Stanford University
Instantaneous Controller Switching
10
Torsten Kroeger 19/28 Stanford UniversityIEEE TRO 2010
Torsten Kroeger 20/28 Stanford University
Instantaneous State Space Switching
11
Torsten Kroeger 21/28 Stanford University
Torsten Kroeger 22/28 Stanford University
Unforeseen Switching of Reference Frames
12
Torsten Kroeger 23/28 Stanford University
Reference Frame A Reference Frame B
Torsten Kroeger 24/28 Stanford University
Instantaneous Reactions to Sensor Events
13
Torsten Kroeger 25/28 Stanford University
• Stabilizing
switched-systems
Velocity-acceleration plane in state space:
ICRA 2010
Torsten Kroeger 26/28 Stanford University
Summary
• Manipulation Primitives as
- a general interface to hybrid switched-control systems for
robot motion control, and
- a “language” to specify sensor-guided and sensor-guarded
robot motions and tasks (� adaptive selection matrix).
• Reflexxes Motion Libraries provide on-line trajectory generation
algorithms to
- guarantee continuous jerk-limited motions during abrupt
switchings between Manipulation Primitives, and to
- provide a safe backup controller in a hybrid switched-system.
14
Torsten Kroeger 27/28 Stanford University
Acknowledgements
Literature
• Please google for on-line trajectory generation.
- T. Kröger. On-Line Trajectory Generation in Robotic Systems.
Springer STAR Vol. 58, 2010.
- T. Kröger, F. M. Wahl. On-Line Trajectory Generation: Basic
Concepts for Instantaneous Reactions to Unforeseen Events.
IEEE T-RO, 2010.
- T. Kröger. On-Line Trajectory Generation: Straight-Line
Trajectories. IEEE T-RO, 2011.
Torsten Kroeger 28/28 Stanford University
T. Kroeger, B. Finkemeyer:
Robot Motion Control During Abrupt Switchings Between
Manipulation Primitives.
Acknowledgements
Thank You for Your Attention!
15
Torsten Kroeger 29/28 Stanford University
The End!
top related