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Nonlinear Adaptive Control Of Teleoperation Systems Subject To Uncertainties

Posted on:2012-06-10Degree:DoctorType:Dissertation
Country:ChinaCandidate:X LiuFull Text:PDF
GTID:1228330368498521Subject:Detection Technology and Automation
Abstract/Summary:PDF Full Text Request
In a teleoperation system, the human operator applies commands to the master. The slave receives these commands through the communication channel and accomplishes the desired task instead of human in the environments that are inaccessible or too hazardous. The most important performance requirement of teleoperation systems is transparency, i.e., the slave exactly reproduces the master’s position trajectory for the environment and the master accurately displays the slave-environment contact force to the operator,so that the operator has the sensation that he/she is directly interacting with the environment. However, in a teleoperation system, uncertainty is an important source of transparency limitations, which may lead to significant position and/or force tracking errors,or even destabilize the systems.In this dissertation, we focus on developing new nonlinear adaptive control schemes of teleoperation systems in the presence of parametric uncertainties (including dynamic parameters, kinematic parameters, linearized parameters (LP) and nonlinearized parameters (NLP)) and external disturbance. These control schemes are based on PEB (Position Error Based) and 4-CH (4-Channel) teleoperation architectures, respectively. Stability and transparency of the overall system are the subjects of our studies. The contributions of this dissertation are as follows:1) For the dynamic and kinematic parametric uncertainties in teleoperation systems, an adaptive control scheme is proposed based on PEB. The combined models of master/operator and slave/environment are built. A nonlinear adaptive control scheme based on PEB is designed, and the stability and the convergence of position tracking error of the system are studied via Lyapunov theory. Simulation and analysis show that the proposed controller can deal with both dynamic and kinematic parametric uncertainties, and the position and force tracking performances of the system are good.2) For the LP (Linearized Parameters) and NLP (Nonlinearized Parameters) uncertainties in teleoperation systems, an adaptive control scheme based on 4-CH is proposed. The nonlinear model of teleoperation systems with NLP uncertainties is developed. Adaptive controllers are designed for the master and the slave, respectively. These controllers are incorporated into 4-CH. The stability, the convergence of position tracking error and the boundedness of force tracking error are studied. Simulation and analysis demonstrate that the proposed control scheme can deal with both LP and NLP uncertainties, and the position and force tracking performances of the system are good.3) For the dynamic parametric uncertainties in teleoperation systems, an adaptive inverse dynamics control scheme based on 4-CH is proposed. The nonlinear task-space dynamic model of teleoperation systems is developed. Next, adaptive inverse dynamics controllers are designed for the master and the slave, respectively. These controllers are incorporated into 4-CH. The stability, the convergence of position and force tracking error are studied. Simulation and analysis demonstrate that the position and force tracking performances of the system are good. Besides, the proposed control scheme does not depend on exact dynamic parameters and can yield linear and decoupled closed-loop, which makes the transparency of the system is easy to study.4) For external disturbance and parametric uncertainties, a disturbance observer-based adaptive controller (DOBAC) is proposed. Nonlinear dynamic model of teleoperation systems subject to external disturbance is established. Then nonlinear disturbance observers are designed for the master and the slave, respectively, to estimate and compensate for the external disturbance. Next, based on the disturbance observers, adaptive controllers are designed to deal with the uncertain dynamic parameters. The DOBACs are incorporated into 4-CH. The stability, the convergence of position error and the boundedness of force error are studied. Simulation and analysis show that the position and force tracking performances of the system are good.
Keywords/Search Tags:uncertainties, nonlinear teleoperation systems, adaptive control, stability, transparency
PDF Full Text Request
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