• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.3
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• pp.213-219
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• 2021

In this paper, an incremental twisting compensator is proposed for improving the performance of helicopter control and tested on an in-house full-scale helicopter simulator. The proposed compensator has a merit in that an incremental control input (a second-order sliding mode control input or so-called twisting control input) is simply added to improve the performance of helicopter control, while the original flight control structure remains untouched. The proposed control technique has been shown to improve the transient and steady-state response of the in-house helicopter simulator.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.5
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• pp.373-381
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• 2020

Quadrotor is simple to model because of the symmetric structure but it has the disadvantage of being relatively sensitive to the external disturbance and system uncertainty. The PID technique applied for the attitude control of quadrotor has been applied comprehensively, but it has a disadvantage that is hard to precise control in the nonlinear system. In this work, a quadrotor attitude control law using the super twisting algorithm is studied, which has robust characteristics against disturbance and system uncertainty. To evaluate the attitude performance by the proposed technique, simulation studies and actual flight tests are carried out, and compared with the conventional PID controller.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.953-959
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• 2018

This paper deals with controlling surge oscillations of a mooring vessel system under large external disturbances such as wind, waves and currents. A control synthesis based on Sliding Mode Control (SMC) with a Super-Twisting Algorithm (STA) has been applied to suppress nonlinear surge oscillations of a two-point mooring system. Despite the advantages of robustness against parameter uncertainties and disturbances for SMC, chattering is the main drawback for implementing sliding mode controllers. First-order SMC shows convergence within the desired level of accuracy, in which chattering is the main obstacle related to the destructive phenomenon. Alternatively, STA completely eliminates chattering phenomenon with high accuracy even for large disturbances. SMC based on STA is an effective tool for the motion control of a nonlinear mooring system because it avoids the chattering problems of a first-order sliding mode controller. In addition, the error trajectories of controlled mooring systems implemented by means of STA form in the bounded region. Finally, the control gain effect of STA can be observed in sliding surface and position trajectory errors.