Browsing by Author "Huang, JT"

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Contact friction compensation for robots using genetic learning algorithms
(1998-10-01)
Liaw, DC
;
Huang, JT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, the issues of contact friction compensation for constrained robots are presented. The proposed design consists of two loops. The inner loop is for the inverse dynamics control which linearizes the system by canceling nonlinear dynamics, while the outer loop is for friction compensation. Although various models of friction have been proposed in many engineering applications, frictional force can be modeled by the Coulomb friction pins the viscous force. Based on such a model, an on-line genetic algorithm is proposed to learn the friction coefficients for friction model. The friction compensation control input is also implemented in terms of the friction coefficients to cancel the effect of unknown friction. By the guidance of the fitness function, the genetic learning algorithm searches for the best-fit value in a way like the natural surviving laws. Simulation results demonstrate that the proposed on-line genetic algorithm can achieve good friction compensation even under the conditions of measurement noise and system uncertainty. Moreover, the proposed control scheme is also found to be feasible for friction compensation of friction model with Stribeck effect and position-dependent friction model.
Contact friction compensation for robots using genetic learning algorithms
(1998-10-01)
Liaw, DC
;
Huang, JT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
In this paper, the issues of contact friction compensation for constrained robots are presented. The proposed design consists of two loops. The inner loop is for the inverse dynamics control which linearizes the system by canceling nonlinear dynamics, while the outer loop is for friction compensation. Although various models of friction have been proposed in many engineering applications, frictional force can be modeled by the Coulomb friction pins the viscous force. Based on such a model, an on-line genetic algorithm is proposed to learn the friction coefficients for friction model. The friction compensation control input is also implemented in terms of the friction coefficients to cancel the effect of unknown friction. By the guidance of the fitness function, the genetic learning algorithm searches for the best-fit value in a way like the natural surviving laws. Simulation results demonstrate that the proposed on-line genetic algorithm can achieve good friction compensation even under the conditions of measurement noise and system uncertainty. Moreover, the proposed control scheme is also found to be feasible for friction compensation of friction model with Stribeck effect and position-dependent friction model.
Global stabilization of axial compressors using nonlinear cancellation and backstepping designs
(1998-12-01)
Liaw, DC
;
Huang, JT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Issues concerning the global stabilization of axial compressors are presented Instead of locally stabilizing the bifurcated rotating stall equilibria to avoid suddern performance drop, control schemes are proposed to globally stabilize the unstalled nominal operating paints. These are achieved by employing nonlinear cancellation and backstepping designs via either throttle or direct mass flow rate control if the compressor characteristic satisfies the 'left-tilt' property. The designs not only guarantee a safe operation close to the maximum achievable pressure rise, but the bifurcated system equilibria are also found to be stabilized due to the elimination of the jump phenomenon. Though both throttle and direct mass flow rate control schemes can be implemented for global stabilization, numerical simulations demonstrate that direct mass flow rate control achieves better post-stall system behaviour.
Robust stabilization of a centrifugal compressor with spool dynamic's
(2002)
Liaw, DC
;
Song, CC
;
Huang, JT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Issues. of global stabilization of a centrifugal compressor with spool dynamics are presented. Control schemes are designed for systems with and without system uncertainty. While actuating only the close-coupled valve or the throttle as the single control input, backstepping tools axe first used to achieve global stability of the working equilibrium for systems without uncertainty. The uncertainties in the spool dynamics and the compressor characteristic are known to be likely to happen in practical applications. Under such circumstances, the compressor torque and the close-coupled valve are then employed to achieve robust global stability of the working equilibrium via the Lyapunov redesign method. Numerical simulations are given to demonstrate the main results.
Robust stabilization of a centrifugal compressor with spool dynamics
(2004-11-01)
Liaw, DC
;
Song, CC
;
Huang, JT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Issues of global stabilization of a centrifugal compressor with spool dynamics are presented. Control schemes are designed for systems with and without system uncertainty. While activating only the close-coupled valve or the throttle as the single control input, backstepping tools are first used to achieve global stability of the working equilibrium for systems without uncertainty. The uncertainties in the spool dynamics and the compressor characteristic are known to be likely to happen in practical applications. Under such circumstances, the compressor torque and the close-coupled valve are then employed to achieve robust global stability of the working equilibrium via the Lyapunov redesign method. Numerical simulations are given to demonstrate the main results.
Robust stabilization of axial flow compressor dynamics via sliding mode design
(2001-09-01)
Liaw, DCR
;
Huang, JT
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Issues of the robust stabilization for axial-flow Compressor dynamics with respect to the uncertainty in axisymmetric characteristics are presented. This is achieved by the design of sliding mode controllers. By assuming an actuation directly modulating the mass flow such as the close-coupled valve, the domain of attraction for the unstalled operating equilibrium will be enlarged to a great extent. Nonlocal robust stability of the operating equilibrium, with respect to the uncertainty in the unstable branch of axisymmetric compressor characteristic, is also provided by the proposed control laws. Moreover, it is demonstrated that the robust control scheme can be employed to fulfill the task of stall recovery. The proposed stabilization design does not require an explicit fin-in for compressor characteristic.