Soon-Geul Lee

Walking Intent-Based Movement Control for JAIST Active Robotic Walker

This paper presents a novel interactive control for our assistive robotic walker, the JAIST Active Robotic Walker (JARoW), developed for elderly people in need of assistance. The aim of our research is to recognize characteristics of the users gait and to generate the movement of JARoW accordingly. Specifically, the proposed control enables JARoW to accurately generate the direction and velocity of its movement in a way that corresponds to the users variable walking behaviors. The algorithm and implementation of the control are explained in detail, and the effectiveness and usability of JARoW are verified through extensive experiments in everyday environments.

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.

Performance Evaluation Criteria for Autonomous Cleaning Robots

This paper is a report on the initial trial for its kind in the development of the performance index of the autonomous mobile cleaning robot. The unique characteristic features of the cleaning robot have been identified as autonomous mobility, dust collection, and operation noise. Along with the identification of the performance indices the standardized performance-evaluation methods including the corresponding performance evaluation platform for each indices have been developed as well. The validity of the proposed performance evaluation methods has been demonstrated by applying the proposed evaluation methods on two commercial cleaning robots available in market. The proposed performance evaluation methods can be applied to general-purpose autonomous service robots which will be introduced in the consumer market in near future.

Partial Feedback Linearization Control of the three dimensional overhead crane

Based on the partial feedback linearization, a novel nonlinear controller is analyzed and designed for three dimensional motion of overhead crane. Three control inputs composed of bridge moving, trolley travelling, and cargo hoisting forces are used to drive five state variables consisted of bridge motion, trolley movement, cargo hoisting displacement, and two cargo swing angles. The control scheme is constituted by linearly combining two components: one is got from the nonlinear feedback of actuated states and the other is received from that of un-actuated states. To verify the quality of control process, the numerical simulation is executed. The received results show that the proposed controller asymptotically stabilizes all system states.

Nonlinear controls of a rotating tower crane in conjunction with trolley motion

Based on two nonlinear control techniques composed of partial feedback linearization and sliding mode control, the robust nonlinear controllers are successfully designed in the case of crane’s complicated operation in which a combination of trolley translation and tower rotation is considered. The proposed controllers concurrently implement four duties well: rotating tower and moving trolley to desired positions from their initial positions precisely, keeping small the cargo swings during transport process, and completely suppressing them at cargo destination. The simulation results show the high qualities of system responses and asymptotical stability of all state trajectories. The robustness of two suggested controllers is also analyzed and compared through simulation.

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.

Nonlinear feedback control of container crane mounted on elastic foundation with the flexibility of suspended cable

This study constructs an original mathematical model of a shipboard container crane and proposes a nonlinear controller for the complicated operation duties in which the viscoelasticity of seawater and the flexibility of handling cable are taken into account. By using two inputs, namely, the pulling force of the trolley and the torque of the hoist, the controller simultaneously drives six outputs, including trolley motion, cable length, container swing, axial container oscillation, ship roll, and ship heave. The effects of elasticity factors and wave excitations on system performance are also investigated. The simulation and experiment results reveal that the controlled system responses remain stable and consistent despite disturbances.

Simulation and Experimental Methods for Media Transport System: Part II, Effect of Normal Force on Slippage of Paper

Many daily appliances for examples copiers, printers and ATMs contain the media transport system (MTS) and the slippage between the medium in the MTS deteriorates the performance quality of the whole system The slippage of the medium in the MTS is affected by many parameters including the friction coefficient between the feeding rollers and the medium, the velocity of the feeding rollers, and the normal force exerted on the medium by feeding rollers This paper focuses on the effect of the normal force on the slippage while the medium is being fed For this purpose, we developed a two-dimensional simulation model for a paper feeding system. Using the simulation model, we calculated the slippage of the paper for different normal forces We have also constructed a testbed of the paper feeding system to verify the simulation results Experimental results are compared with the simulation resultsKey Words: Media Transport System, Slippage, Normal Force, Friction Coefficients, Paper Modeling

Sensor-Based Incremental Boustrophedon Decomposition for Coverage Path Planning of a Mobile Robot

This paper presents a sensor-based coverage algorithm with which a robot covers an unknown rectilinear region while simultaneously constructing cell decomposition. In this algorithm, cell boundaries are indicated by combined lines of critical edges those are sensed partial contours of wall and objects in the workspace. The robot uses the laser scanner to sense critical edges. The proposed algorithm incrementally (one by one) decomposes unknown environment into cells. The constructing order of the cells is very important in this incremental cell decomposition algorithm. In order to decide next target cell from candidate cells, the robot checks redundancy of the planned path and possible position of ending points of the current cell. The key point of the algorithm is memorizing the covered space to define the next target cell from possible cells more than one. Path generation within the defined cell is determined to minimize the number of turns because the number of turns is the main factor to save time for coverage. Therefore, the long boundary of cell should be chosen as a main path of the robot. Verification of this algorithm is done by the simulation under LABVIEW environment.

Implementation of Smart Floor for multi-robot system

In this paper, we suggest a new information space concept called Smart Floor. Smart Floor is the floor storage of specific information intended for route guidance of a mobile robot. A mobile robot can reach its goal position using the information in Smart Floor as well as automatically update information for a changing environment. We constructed Smart Floor using RFID tag packaging and fabricated a mobile robot mounted with a passive RFID tag in ultra high frequency (UHF) bandwidth. The passive RFID tag is inexpensive and does not require a power supply. The primary information saved and stored in Smart Floor is direction-values and Q-values. These values are the result of applying Q-learning in an arbitrary position to the goal position in the Grid world. The research will help from Smart Floor and aid in the development of various applications for multi-robot application.