Sang-Chan Moon

Partial feedback linearization and sliding mode techniques for 2D crane control

The overhead crane is an under-actuated system because its degree of freedom is larger than that of actuators. The three state variables of trolley motion, cargo lifting motion and cargo swing are controlled by two input signals composed of trolley driving and cargo lifting forces. In the present study, a novel non-linear control scheme for an overhead crane is proposed based on the combination of two control design techniques. The cargo swing vanishing mechanism is constructed using partial feedback linearization. Control of trolley and cargo tracking is designed based on the sliding mode technique. An anti-swing structure is then merged with the tracking scheme of the trolley and cargo hoisting motions to enable indirect control of the cargo swing angle. Both simulation and experimental results show that the combined controller not only stabilizes all trajectories of system states but also guarantees the robustness in which the shapes of system responses are consistently retained despite the wide variation in crane parameters.

Detecting Lane Departure Based on GIS Using DGPS

This paper proposes a method utilizing Differential Global Position System (DGPS) with Real-Time Kinematic (RTK) and pre-built Geo-graphic Information System (GIS) to detect lane departure of a vehicle. The position of a vehicle measured by DGPS with RTK has 18 cm-level accuracy. The preconditioned GIS data giving accurate position information of the traffic lanes is used to set up coordinate system and to enable fast calculation of the relative position of the vehicle within the traffic lanes. This relative position can be used for safe driving by preventing the vehicle from departing lane carelessly. The proposed system can be a key component in functions such as vehicle guidance, driver alert and assistance, and the smart highway that eventually enables autonomous driving supporting system. Experimental results show the ability of the system to meet the accuracy and robustness to detect lane departure of a vehicle at high speed.

Adaptive sliding mode control of three dimensional overhead cranes

An overhead crane transfers the payloads of various volumes and weights depending on the each operation case. The friction factors characterized by damped coefficients can be changed in connection with operating environment. This study develops an adaptive version of sliding mode controller for the overhead cranes without priori information of cargo mass and damped aspects. The controller simultaneously executes five duties consisted of tracking the trolley and bridge, hoisting the cargo, keeping the payload swings small during the transport process, and absolutely suppressing the cargo vibrations at destinations of trolley and bridge. The simulation results indicate that the controller asymptotically stabilizes all system responses.

Assessment and Reliability Validation of Lane Departure Assistance System Based on DGPS-GIS Using Camera Vision

This paper proposes a new assessment and reliability validation method of Lane Departure Assistance System based on DGPS-GIS by measuring lanes with camera vision. Assessment of lane departure is performed with yaw speed measurement and determination method for false alarm of ISO 17361 and performance validation is executed after generating departure warning boundary line by considering deviation error of LDAS using DGPS. Distance between the wheel and the lane is obtained through line abstraction using Hough transformation of the lane image with camera vision. Evaluation validation is obtained by comparing this value with the distance obtained with LDAS. The experimental result shows that the error of the extracted distance of the LDAS is within 5 cm. Also it proves performance of LDAS based on DGPS-GIS and assures effectiveness of the proposed validation method for system reliability using camera vision.

A study about curve extraction and lane departure determination of linear curved road

Recently, intelligent vehicle are required accurate information about road condition for safety driving. However, vehicle safety systems are irregularly caused an error in judgment by road patterns. In this study, which has extracted curve road segments from line information of GIS with alignment of road. This algorithm are based modified Bezier curve method to detect curve lines from straight lines. Extracted line information are formally analyzed with lane departure warning system (LDWS) that was robust curves. For performance evaluation, the system has installed DGPS with 20 cm RMS and WAVE communication with 5.8 GHz, and implemented vehicle test in road environment with groups of curves and straight lines. Curvature LDWS improve correctness criterion by applying to predicted trajectory condition to previous algorithm. Test results are shown robust determination and confirmed false alarm did not appear. Furthermore, this algorithm are not only reduced error of functioning properly, but also detected lane departure at all-road environments in real-time.

Pose tracking control of an omni-directional wheel-type robot for a heavy-water nuclear reactor

In this paper, a PID controller is designed to solve position and orientation tracking control of a robot for a heavy-water nuclear reactor when the robot keeps track of a circular reference trajectory to show mobility for small turning radius. The four-wheel-drive robot is designed to have two omni-directional rear wheels for mobility and the tool center is located just above of the geometric center of the mobile base for stability. The complex nonlinear system dynamics of the omni-directional wheel-type robot is modeled with the RecurDyn. Using this dynamic model, a linear control theory based on a two wheel differential-drive robot is applied to design the robot controllers. The control strategy needs not only to keep track of a trajectory of a small radius, but also to locate the tools center to the proper position, with only position and orientation measurement. The co-simulation between RecurDyn and CoLink is built with the derived control strategy and some simulated results are presented.

Motion Control Algorithm Expanding Arithmetic Operation for Low-Cost Microprocessor

For precise motion control, S-curve velocity profile is generally used but it has disadvantage of relatively long calculation time for floating-point arithmetics. In this paper, we present a new generating method for velocity profile to reduce delay time of profile generation so that it overcomes such disadvantage and enhances the efficiency of precise motion control. In this approach, the velocity profile is designed based on the gamma correction expression that is generally used in image processing to obtain a smoother movement without any critical jerk. The proposed velocity profile is designed to support both T-curve and S-curve velocity profile. It can generate precise profile by adding an offset to the velocity profile with decimals under floating point that are not counted during gamma correction arithmetic operation. As a result, the operation time is saved and the efficiency is improved. The proposed method is compared with the existing method that generates velocity profile using ring buffer on a 8-bit low-cost MCU. The result shows that the proposed method has no delay in generating driving profile with good accuracy of each cycle velocity. The significance of the proposed method lies in reduction of the operation time without degrading the motion accuracy. Generated driving signal also shows to verify effectiveness of the proposed method.