Robust, near time-optimal control of nonlinear second order systems with model uncertainty

Author(s):  
K.H. You ◽  
E.B. Lee
1991 ◽  
Vol 113 (3) ◽  
pp. 363-370 ◽  
Author(s):  
W. S. Newman ◽  
K. Souccar

A technique is presented for controlling second-order, nonlinear systems using a combination of bang-bang time-optimal control, sliding-mode control, and feedback linearization. Within the control loop, a state space evaluation of the system classifies the instantaneous dynamics into one of three regions, and one of three corresponding control algorithms is invoked. Using a prescribed generation of desirable sliding surfaces, the resulting combined controller produces nearly time-optimal performance. The combination controller is provably stable in the presence of model uncertainty. Experimental data are presented for the control of a General Electric GP132 industrial robot. The method is shown to achieve nearly time-optimal motion that is robust to modeling uncertainties. Representative transients compare favorably to bang-bang control and PD control.


2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Wookjin Sung ◽  
Jiecai Luo ◽  
Kwanho You

In this paper, we suggest how to enlarge the maximum controllable region for unstable linear systems with mixed control actions. Using the impulsive action as an alternating control input, it is shown how the collaborative control inputs (bang-bang and impulsive action) work to augment the controllable region of unstable second order systems. However, the weakness resides in the sensitivity to model uncertainty and the time-consuming work to construct the switch curves (bang-bang switch curve and impulse firing curve). We suggest an efficient way to approximate the switch curves. It overcomes the shortcomings from the use of original switch curves, which are constructed through time backward computation. Simulation results show how the approximate switch curves can be used to determine the optimal control values for an augmented maximum controllable region.


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