Wave-variable framework for networked robotic systems with time delays and packet losses

2016 ◽  
Vol 48 (7) ◽  
pp. 1472-1484 ◽  
Author(s):  
Seng-Ming Puah ◽  
Yen-Chen Liu
Keyword(s):  
Time Delays ◽  
Robotic Systems ◽  
Packet Losses ◽  
Wave Variable

Transparent four-channel bilateral control architecture using modified wave variable controllers under time delays

Robotica ◽  
2014 ◽  
Vol 34 (4) ◽  
pp. 859-875 ◽  
Author(s):  
Da Sun ◽  
Fazel Naghdy ◽  
Haiping Du
Keyword(s):  
Time Delays ◽  
Large Time ◽  
Wave Transformation ◽  
Bilateral Teleoperation ◽  
Bilateral Control ◽  
Wave Variable ◽  
Guarantee System ◽  
Remote Environment ◽  
The Stability ◽  
Teleoperation Systems

SUMMARYStability and transparency are two critical indices of bilateral teleoperation systems. The wave variable method is a conservative approach to robustly guarantee system passivity under arbitrary constant time delays. However, the wave-variable-based reflection is an intrinsic problem in this method because it can significantly degrade system transparency and disorient the operator's perception of the remote environment. In order to enhance both the transparency and the stability of bilateral teleoperation systems in the presence of large time delays, a new four-channel (4-CH) architecture is proposed which applies two modified wave-transformation controllers to reduce wave-based reflections. Transparency and stability of the proposed system are analyzed and the improvement in these when using this method is measured experimentally. Results clearly demonstrate that the proposed method can produce high transparency and stability even in the presence of large time delays.

Control Strategies for Distributed Real-Time Control With Time Delays and Packets Losses

2004 ◽  
Author(s):  
Kun Ji ◽  
Ajit Ambike ◽  
Won-Jong Kim
Keyword(s):  
Time Delay ◽  
Real Time ◽  
Packet Loss ◽  
Time Delays ◽  
Open Loop ◽  
Current Control ◽  
Test Bed ◽  
Real Time Control ◽  
Packet Losses ◽  
Time Operation

Investigation on using network for distributed systems is an important topic in the motion control industry. This paper presents solutions to time-delay and packet-loss problems encountered in distributed real-time operation of an open-loop unstable magnetic levitation (maglev) test bed via an Ethernet. A novel model predictive control strategy with optimal controller design is developed to overcome the adverse influences of time delays and packet losses. By using the prediction of system states and the event-driven and time-driven smart actuator simultaneously, the plant receives the current control signal in every sampling interval even at the presence of time delays and packet losses. Thus we can compensate the time-delay and packet-loss in a uniform way. The simulation and experimental results demonstrated the feasibility and effectiveness of this control algorithm for NCSs with long stochastic time delays and successive packet losses.

Wave Variable Based Force Control

2007 ◽  
Author(s):  
J. Scot Hart ◽  
Gu¨nter Niemeyer
Keyword(s):  
Time Delay ◽  
Force Control ◽  
Time Delays ◽  
Communication Channel ◽  
Force Feedback ◽  
Low Frequency ◽  
Force Sensor ◽  
Wave Variable ◽  
Communication Time ◽  
Frictional Forces

Wave variable controllers maintain passive communication across time delays in telerobotics. As passive elements, wave variable controllers interact well with other passive elements, such as P.D. controllers and masses, and use a combination of force and velocity signals to apply force feedback. Currently we are exploring the use of wave variable controllers with large non-backdrivable industrial-type slave devices where dynamics are dominated by inertial and frictional forces. The objective is to integrate force sensor measurements into wave variable controllers to provide low frequency force feedback and hide the slave’s friction and inertia from the user in the presence of a communication time delay. This paper presents and uses a wave variable based approach to design force control. The resulting wave variable based force controller is converted to power variables and shown to be similar to traditional force controllers. A 1-DOF telerobotic system is used to experimentally show the wave variable based force control combines with the enhanced stability properties of the wave communication channel to produce robust slave side force control. The resulting system is better able to maintain force control with rigid environments then a traditional controller both with and without communication time delay.

GUARANTEED COST CONTROL OF NETWORKED CONTROL SYSTEMS WITH TIME-DELAYS AND PACKET LOSSES

2006 ◽  
Vol 04 (04) ◽  
pp. 691-706 ◽  
Author(s):  
SHANBIN LI ◽  
YONGQIANG WANG ◽  
FENG XIA ◽  
YOUXIAN SUN
Keyword(s):  
Control Systems ◽  
Time Delays ◽  
Cost Control ◽  
Networked Control Systems ◽  
Guaranteed Cost Control ◽  
Networked Control ◽  
Linear Matrix ◽  
Packet Losses ◽  
Markovian Jump Linear Systems ◽  
Guaranteed Cost

In this paper, the random time-delays and packet losses issues of networked control systems (NCS) within the framework of guaranteed cost control for Markovian jump linear systems (MJLSs) are addressed. A new delay-dependent sufficient condition for the existence of guaranteed cost controller and an upper bound of the cost function are presented by a new stochastic Lyapunov–Krasovskii functional. The state feedback problem for such system is formulated as a convex optimization over a set of linear matrix inequalities (LMIs) which can be very efficiently solved by interior-point methods. As examples to verify the proposed method, two plants in the networked setup are considered. The simulation results demonstrate the effectiveness of the method.

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