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Tele-Operation systems summer 2013 @ Tehran
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Tele-Operation Systems
Presence of “Linear Control Systems”Lecturer : Mansour.Nch
TeleOperation ConferenceEmail:[email protected]
Tel: +98 – 935 658 9590
Summer 2013
R(S) G(S) F(S)
H(S)
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Introduction indicates operation of a machine at a distance.
but is most commonly associated with robotics and mobile robots
but can be applied to a whole range of circumstances in which a device or machine is
operated by a person from a distance.
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Integrated Model
R(S) G(S) F(S)
H(S)
Tele-Operation System
Human Operator Environment
Xh -Xe
Fh Fe
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Diagram of the bilateral Teleoperation
Master System
Slave System
Communication System
Vm Vmd
fsfsd
I. the human operator commands via a master manipulator by exerting a force fhII. The master moves with velocity: Vm
III. the slave manipulator responds to the reference signal: VmdIV. the force fs sensed as a result of contact with the environment and/or some
external source.V. fe , is transmitted back to the master network, which results in the force fsd to
the master.
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Infrastructures needed
Communication Infrastructure
Control Infrastructure
Network Infrastructure
Security Infrastructure
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Communication Infrastructure
• This Scenario needs a high availability Connection to respond more faster! , so maybe H-system can solve this Problem
H-System
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Master Device Slave DeviceA link with high availability Connection
Usually uses Fiber-Optic TechnologyWhen Master fails , Slave Portion Detect this fault immediately
and achieve the control mechanism so fast!
This is a High Redundant Scenario
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Control Infrastructure
Human Operator
Hand Controller
Local Delay Compensation
Environment
Remote Delay Compensation
Mobile robot
H1
H2
Delay
Delay
Remote SiteLocal Site
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A big challenge: Time DelayWhen local station sends electronic bits to remote station, some delay will be appeared in system output. several methods are presented since 1957 considering time delay.
1. in 1957, Time delay problem in process control was first tackled by Smith
2. 1981, Vertut showed that the stability of teleoperation systems with delay time could be achieved by decreasing bandwidth of the system
3. In 1997, Niemeyer and Slotine used wave variables method in teleoperation systems using passivity theory
4. In 1999, Maza and Velasco-Villa predicted the state of linear systems with time-delays in the input and the state
5. Park and Cho applied sliding mode methods for controller design in teleoperation systems with delay time in 1999
6. Prediction, generally in the form of smith predictors (smith 1957), can be combined with wave-based systems to reduce the effects of the delay (Ganjefar, Momeni & Janabi-sharifi 2002)
7. In 2003 Azorin used A new control method of teleoperations with time delay
8. In 2006 Sirouspour used a LQG controller in teleoperation systems with constant time delay
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Teleoperation Types• Remote teleoperation can be classified into unilateral• and bilateral.
• Unilateral : no force feedback is available to the user.• bilateral: force feedback allows the user to have a better
feeling for the remote environment.
• This classification contributes more extensive sense of telepresence
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General Bilateral Teleoperation
• Bilateral: When the contact force is reflected via the master• actuator to the operator’s hand, the teleoperator system• is said to be bilateral or force reflecting.
• A bilateral teleoperation Components
Human Master Controller Slave Environment
Vh Vm Vmd Ve
fh fsd fs fe
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Scenario of Time Delay in WAN
• The challenge of delivering a packet to the remote station contains the following factors:
• 1. TTL • 2. bandwidth• 3. WAN Speed• 4. security parameters • 5. signal processing (Noise , etc.)
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Wave variables method• presents a modification or extension to the theory of passivity• This method is also closely related to the scattering and small
gain theories.
b
√(2b)
√(2b)
X
F
U
VF is force
X is velocityU is forward
V is backward
The basic wave transformation
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SMITH Predictor Method• For systems with a pure transport lag• allowed for a high loop gain in order to provide better accuracy
• C(s) is a proportional controller (i.e. C(s)=k)• P(s) is a first order filter with transport lag •
•C(s)=k ;
C(S) P(S) r e u y
( )1
TseP S
Ts
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( )
( ) 1
Ts
Ts
y s Ke
r s Ts Ke
( )S
A Delay Term has been appeared in characteristic equation
So, What the scenario?
In order to remedy this problem SMITH proposed a minor correction loop around the controller
C(S)e u
•
P(S)(1-e^TS) Compensation loop
C(S) P(S) r e u y
•
P(S)(1-e^TS)
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C(S) P(S) r e u y
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C(S) P(S) r e u y
•
P(S)(1-e^TS)
The closed-loop system is stable for any ∆T if:
and for a finite ∆T , if :
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Network Infrastructure• Commonly Operating in a Isolated Network• Using Cisco Technologies
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Conclusion
Velocity in master and slave (rad/s)
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Position in master and slave (rad)
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Force in Master/slave (N.m)
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Position error in master and slave (rad.)
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Velocity error in master and slave (rad./s)
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ReferencesIEEE Journals:
[1] G. Niemeyer and J.-J. E. Slotine. “Using WaveVariables for system Analysis and Robot Control”.Proc. 1997 IEEE. Int. Conf. Robotics andAutomation, Albuquerque, New Mexico, pp 1619-1625.
[2] J. H. Park and H. Cho, “Sliding–Mode Controller for Bilateral Teleoperation with Varing Time Delay
[3] Elhajj and N. Xi, “Real–Time Control of Internet Based Teleoperation with Force Reflection”, Proc. 2000 IEEE Int. Conf. Robotics and Automation, San Francisco CA, April 2000.
