• The Journal of Korea Robotics Society
• /
• v.6 no.2
• /
• pp.97-107
• /
• 2011

This paper describes efficient flight control algorithms for building a reconfigurable ad-hoc wireless sensor networks between nodes on the ground and airborne nodes mounted on autonomous vehicles to increase the operational range of an aerial robot or the communication connectivity. Two autonomous flight control algorithms based on adaptive gradient climbing approach are developed to steer the aerial vehicles to reach optimal locations for the maximum communication throughputs in the airborne sensor networks. The first autonomous vehicle control algorithm is presented for seeking the source of a scalar signal by directly using the extremum-seeking based forward surge control approach with no position information of the aerial vehicle. The second flight control algorithm is developed with the angular rate command by integrating an adaptive gradient climbing technique which uses an on-line gradient estimator to identify the derivative of a performance cost function. They incorporate the network performance into the feedback path to mitigate interference and noise. A communication propagation model is used to predict the link quality of the communication connectivity between distributed nodes. Simulation study is conducted to evaluate the effectiveness of the proposed reconfigurable airborne wireless networking control algorithms.

• Korean Chemical Engineering Research
• /
• v.58 no.3
• /
• pp.390-395
• /
• 2020

For some processes with saturations, economical operating points are on the saturation edges. Traditional feedback controllers cannot be used to regulate such processes on the saturation edges because there are abrupt dynamics changes and no feedback information at saturations. Optimization-based methods such as the model predictive control can treat this control problem without difficulty when the saturation levels and dynamics are known and not varying. Otherwise, an adaptation scheme to track the saturation levels and dynamics should be included. Here, for very simple methods to treat this control problem, two control methods based on the recent slope seeking method and the relay feedback method are proposed. Their performances are evaluated with simulations applying them to a second order liquid level system with saturation. Simulations show that these proposed control methods can find and maintain operating point of the saturation edge under 5% relative error.

• Korean Chemical Engineering Research
• /
• v.58 no.2
• /
• pp.184-189
• /
• 2020

Van de Vusse reactors show the maximum points in input-output steady state maps and dramatic changes in their dynamic characteristics around those maximum points. According to their operating regions, there appear sign changes in steady state gains and nonlinear characteristics such as non-minimum phase dynamics which cause difficulties in applying controllers. Many nonlinear controllers that are available and newly designed are applied to these Van de Vusse reactor processes and their performances are tested. Reactor examples with real reactions have been reported. However, due to difficulties in constructing and operating chemical reactor systems, they are not adequate to be used for real applications of control experiments and hence most of results are based on simulations studies. Here, we propose a liquid level system that realizes most of the steady state and dynamic characteristics of Van de Vusse reactor, and two nonlinear control methods that can be used as base methods to compare nonlinear controllers newly designed. Liquid level experimental system and two nonlinear control methods are very simple and can be used to test performances of nonlinear controllers in practice.