Papers by Author: Chi Cheng Cheng

Abstract: Stabilization and tracking control of nonlinear uncertain underactuated systems are always challenging problems because underacturated systems have fewer independent control actuators than degrees of freedom to be controlled. For a class of second order underactuated mechanical systems, a robust finite time control strategy is developed in this paper. The robust finite time controller is to drive the tracking error to be zero at the fixed final time. In fact, finite time convergence implies nonsmooth or non-Lipschitz continuous autonomous systems with nonuniqueness of solution. In order to prove the stability, we present a generalized Lyapunov stability proof for the second order underactuated mechanical system. By utilizing a Lyapunov stability theorem, we can achieve finite time tracking of desired reference signals for underactuated systems, which is subject to both external disturbances and system uncertainties. The proposed control scheme is demonstrated by actual experiments on a Furuta pendulum system. Based on the experiment results, the finite time convergence of system errors can be assured.

Abstract: The quadrotor helicopter is designed to easily move in particular environments because it can take off and land in limited space and easily hover at a fixed location. For this reason, a robust adaptive sliding mode controller is developed to control of a quadrotor helicopter in the presence of external disturbances and parameter uncertainties. The quadrotor helicopter system is a typical underactuated system, which has fewer independent control actuators than degrees of freedom to be controlled. The main contribution here is to afford simulation and verification for the quadrotor helicopter flight controller under the assumption of unknown parameters. By utilizing the Lyapunov stability theorem, we can achieve asymptotic tracking of desired reference commands for the quadrotor helicopter, which is subject to both external disturbances and parametric uncertainties. From the simulation results, the controller was sufficient to achieve position and attitude control of the quadrotor helicopter system, which permits possible real time applications in the near future.

Abstract: In this paper, a robust adaptive control strategy is proposed for trajectory control of an omnidirectional vehicle with three omni-wheels, which have the ability to move simultaneously with independently rotational motion. Actuators of the omnidirectional vehicle contain uncertainties and their parameters are unknown. By the Lyapunov stability, the asymptotic tracking performance can be assured. The proposed control scheme is demonstrated by actual tracking experiments using the omnidirectional vehicle system. Experimental results showed promising tracking performance for the proposed method as compared to traditional sliding mode controller.

Abstract: In order to fully understand dynamic behavior of the thickness variation and conduct off-line process tuning, a dynamic simulator for the feedforward Automatic Gauge Control (AGC) for a hot strip finishing mill in China Steel Corporation is developed. One of the major factors influencing on deviation of delivery thickness of the steel strip is the temperature variation caused by cyclic contact between the steel strip and beams, which transfer the strip in the hot rolling process. This temperature difference brings about hardness variation along the strip, which is known as skid marks. Simulation results and system analysis verify that the feedforward AGC system is capable of overcoming the high frequency thickness variation disturbed by the cyclic temperature difference, which usually cannot be effectively compensated by regular gaugemeter AGC feedback loop. A strategy to locate the optimal feedforward gain is also proposed.

Abstract: The goal of this research is to develop a design and optimization methodology for the mechatronic modules of machine tools by treating all important characteristics from all involved engineering domains in one single process. In this study, a mechatronic system of machine tools was broken into a structure and control two-level systems. In the first stage for structure design process, the Pro/E was used to build up the 3D models and the AnSys was employed to design the mechanical structure and select the optimal components for the machine tools. Next, in the control design process, a common controller type was designed by MATLAB in this stage. Then, three important parameters were established for the machine tools design to achieve the overall system performance.

Abstract: Methods of standard genetic algorithm (SGA) and adaptive genetic algorithm (AGA) are employed to improve performance of global cutting for an arbitrary closed region. Normal conditions and special types of the closed region are also analyzed and discussed by the area map. It appears that the presented GA frameworks are superior to the blind search algorithm (BSA) and are suitable for the special types of remaining closed space (RCS). By comparing three experimental results, it can be concluded that area efficiency and time reduction are trade-offs.