Kyo Il Lee

Real-time identification of road-bank angle using differential GPS

This brief presents a new approach to identify road-bank angle in real time using differential global positioning system (GPS)-based measurements. In the proposed approach, unknown vehicle parametric variations are decoupled from road-bank angle information by appropriate identification-oriented parameterization of the lumped disturbance. Three alternative estimation approaches are then developed using the parameterized model for real-time bank angle identification. These include a parameter identification algorithm for linear systems, an adaptive observer and a disturbance observer combined with an adaptive gradient law. The estimators are augmented with intuitive projection algorithms in order to enhance the efficacy of the algorithms. The performance and accuracy of the proposed algorithms is evaluated by both numerical simulation and experimental results. The advantages and disadvantages of each of the three estimation algorithms are described.

An integrated bio cell processor for single embryo cell manipulation

In this paper, we present a novel integrated bio cell processor to handle individual embryo cells. Its functions are composed of transporting, isolation, orientation, and immobilization of cells. These functions are essential for biomanipulation of single cells, and have been typically carried out by a proficient operator. The purpose of this study is the automation of these functions for effective cell manipulation using a MEMS based bio cell processor. This device is realized with relatively simple design and fabrication process. To transport cells, microfluidic channel is employed. The isolation of a cell is performed by actuation of polypyrrole (PPy) valves. The orientation control of cells is accomplished by dielectrophoresis (DEP). By the suction from the micro-hole, the target embryo cell is immobilized. Experimental results show that this device can substitute the essential but very tiresome and repeatable embryo cell manipulation and contribute significantly to the improvement of speed and success rate of operation by facilitating the cell manipulation. The cell viability test for the device is studied through the distribution of mitochondria in mouse (B6CBA) embryo cells and cultivation of cells for 86 h after cell was manipulated by DEP.

Smooth shift control of automatic transmissions using a robust adaptive scheme with intelligent supervision

In this paper, a robust adaptive control scheme with an intelligent supervisor for vehicle powertrain systems is investigated. The control objectives are to provide smooth shift transients for passenger comfort and to improve component durability. The reaction carrier speed and the turbine speed during the inertia phase are controlled to track their desired speeds, respectively. The boundedness of all signals in the closed loop system and the convergence of the reaction carrier speed error near to zero are guaranteed by applying the Lyapunov stability analysis. The adaptive compensation controller with an intelligent supervisor is implemented to keep the turbine speed error near to zero and the deviation of the shift duration within an allowable range. The proposed control algorithm is implemented and evaluated on an experimental test setup.

Pattern Recognition and Process Planning Prismatic Workpieces by Knowledge Based Approach

Abstract FEXCAPP. a feature oriented and knowledge based generative type CAPP system is presented in the paper. For the CAD/CAPP integration, a feature recognition module based on Directed Edge Data Structure and Attributed Adjacency Graph concepts are utilized. From this features, tool approach direction, tool radius and machining sequence are determined by tree search algorithm. ROHULUS and OPS5 are used as a geometric modeller and an inference engine. And an axiomatic approach is utilized to include the tolerance and machines precision information in determining the cutting conditions. Finally. for CAP/CAM integration. NC codes are automatically generated from the process sequence file and transmitted to the NC milling machine through RS-232C.

Vehicle lateral stability management using gain-scheduled robust control

This paper deals with the design of a yaw rate controller based on gain-scheduled H∞ optimal control, which is intended to maintain the lateral stability of a vehicle. Uncertain factors such as vehicle mass and cornering stiffness in the vehicle yaw rate dynamics naturally call for the robustness of the feedback controller and thus H∞, optimization technique is applied to synthesize a controller with guaranteed robust stability and performance against the model uncertainty. In the implementation stage, the feed-forward yaw moment by driver’s steer input is estimated by the disturbance observer in order to determine the accurate compensatory moment. Finally, HILS results indicate that the proposed yaw rate controller can satisfactorily improve the lateral stability of an automobile.

Robust observer-based monitoring of a hydraulic actuator in a vehicle power transmission control system

Abstract The availability of pressure information of a hydraulic actuator makes it possible to improve the quality of vehicle power transmission via precise feedback control and to realize on-board fault diagnosis. However, the high cost of a pressure sensor has not allowed its widespread deployment despite such apparent advantages. This paper presents an observer-based algorithm to estimate the pressure output of a hydraulic actuator in a vehicle power transmission control system. The proposed algorithm builds on more readily available slip velocity and the models of a hydraulic actuator and a mechanical subsystem. The former is obtained empirically via system identification due to the complexity of the hydraulic actuator, while the latter is derived physically. The resulting robust observer is guaranteed to be stable against possible parametric variations and torque estimation errors. The hardware-in-the-loop studies demonstrate the viability of the proposed algorithm in the field of advanced vehicle power transmission control and fault diagnosis.

Nonlinear Robust Control Design for a 6 DOF Parallel Robot

A class of robust tracking controllers for a 6 DOF parallel robot in the presence of nonlinearites and uncertainties are proposed. The controls are based on Lyapunov approach and guarantees practical stability. The controls utilize the information of link displacements and its velocities rather than using the positions or angles of the 6 DOF platform. This can be done by constructing the linkspace coordinates and the workspace coordinates simultaneously by imposing geometric constraints. The controls utilize the possible bound of uncertainty, and the uniform ultimate ball size can be adjusted by a suitable choice of control parameters. The control performance of the proposed algorithms is verified through experiments.

Bandwidth Maximizing Design for Hydraulically Actuated Excavators

In this paper we address the optimal design of a multi-degree-of-freedom hydraulically actuated excavator for reducing vibration and improving dynamic bandwidth. We specifically consider the problem of maximizing the minimum fundamental frequency of a hydraulic excavator with respect to various actuator and structural design parameters, i.e. the piston areas of the hydraulic cylinders, and the masses and inertias of the mechanical links. An analytic gradient-based optimization algorithm, together with the design sensitivity equations, are derived. Detailed case studies involving a prototype hydraulic excavator are presented.

Nonlinear vehicle stability control using disturbance observer

A disturbance observer-based nonlinear vehicle sta- bility controller is proposed in this paper. The lumped distur- bance to the vehicle yaw rate dynamics has been estimated using the disturbance observer. The disturbance is due to the uncertain factors such as tire forces, vehicle parameters and hydraulic ac- tuator parameters. The estimated disturbance has been used to stabilize the lateral dynamics of the vehicle. The dynamics of the hydraulic actuator is incorporated in the vehicle stability control- ler design procedure using the model reduction technique. Modu- lar control design methodology is adopted to effectively deal with the mismatched uncertainty. Simulation results indicate that the proposed disturbance observer-based vehicle stability controller can achieve the desired reference tracking performance as well as sufficient level of robustness.

Design and Performance Evaluation of a 3-DOF Mobile Microrobot for Micromanipulation

In this paper, a compact 3-DOF mobile microrobot with sub-micron resolution is presented. It has many outstanding features: it is as small as a coin ; its precision is of sub-micrometer resolution on the plane; it has an unlimited travel range; and it has simple and compact mechanisms and structures which can be realized at low cost. With the impact actuating mechanism, this system enable both fast coarse motion and highly precise fine motion with a pulse wave input voltage controlled. The 1-DOF impact actuating mechanism is modeled by taking into consideration the friction between the piezoelectric actuator and base. This modeling technique is extended to simulate the motion of the 3-DOF mobile robot. In addition, experiments are conducted to verify that the simulations accurately represent the real system. The modeling and simulation results will be used to design the model-based controller for the target system. The developed system can be used as a robotic positioning device in the micromanipulation system that determines the position of micro-sized components or particles in a small space, or assemble them in the mesoscale structure.