Hwa Soo Kim

A New Mobile Platform (RHyMo) for Smooth Movement on Rugged Terrain

This paper suggests a new performance metric for a mobile platform called as a posture variation index (PVI) to evaluate the smoothness of its movement, which is an important factor to predict undesired oscillations or shocks on a mobile platform while traveling on rugged terrain. The PVI consists of the height and pitch angle variations of center of mass of a mobile platform. By using the PVI, the movements of well-known mobile platforms are systematically analyzed. In order to ensure smooth movement as well as high terrainability on rugged terrain, a new mobile platform (RHyMo) is constructed on the basis of the kinematic and quasi-static analyses. The extensive experiments are carried out by using the RHyMo and the Rocker-Bogie platform on the artificial rugged terrain, which verify that in comparison with the Rocker-Bogie platform, the average and maximum height variations of RHyMo are reduced by 12.72% and 5.96%, respectively. Moreover, the average and maximum pitch angle variations of RHyMo are significantly reduced by 65.87% and 60.53%, respectively. The terrainability of RHyMo against a high step and steep stairs is improved with the help of the track mechanism installed in the front linkage.

Adaptive impedance control of a cleaning unit for a novel wall-climbing mobile robotic platform (ROPE RIDE)

This paper presents a new position-based adaptive impedance control (PAIC) scheme of a cleaning unit for a novel wall-climbing mobile robotic platform (ROPE RIDE), which can climb up a high-rise building with the help of a rope ascender and two propellers thrusters. To guarantee the cleaning performance of proposed ROPE RIDE, it is crucial to maintain a constant contact force between a cleaning unit and various types of walls. Compared to existing impedance control methods, the proposed PAIC method is not only simple to implement but also robust against external disturbances such as the varying wall positions and materials. Therefore, it can promise the zero steady state force tracking error even for a step-type wall. The extensive experiments in addition to simulations are performed to validate the cleaning performance as well as the stability of proposed adaptive impedance control scheme.

Design and Control of a Cleaning Unit for a Novel Wall-Climbing Robot

This paper presents the design and control of a cleaning unit installed on a novel wall-cleaning robot (ROPE RIDE: RObotic Platform Enabling Rope access In Dangerous Environment). The proposed cleaning unit is able to autonomously avoid various obstacles on the wall of a building and also performs cleaning with sufficient contact force. The prototype of a cleaning unit is systematically designed and examined to verify its impedance-controlled cleaning performance.

Conceptual design of a new stair-climbing mobile platform using a hybrid link mechanism

High mobility performance is the most important key to mobile robots. In this research, a new indoor stair-climbing mobile platform is proposed on the basis of a hybrid-link mechanism. The hybrid link mechanism combining the passive link with the active mechanism can guarantee well-balanced simplicity as well as adaptability performance in comparison with the previous passive mechanisms. First, a requirement list for a stair-climbing indoor mobile platform is made upon the related researches. Then, a new kinematic model of hybrid link mechanism is suggested by using systematic design methodology. For the optimization of design parameters such as wheel radii and link lengths, the cost function is chosen as the combination of the backward movement and the deviation of path angle during climbing up stairs. Then, the optimization of the kinematic variables for the hybrid link mechanism is carried out via generic algorithm.

Development of a new hybrid link based mobile platform

Potential performances of tele-presence mobile platforms and service robots can be greatly enhanced by improving their mobility. So, to maximize mobility becomes a very important subject for indoor mobile platform research. Many mechanisms and control methodologies are suggested, but mobility of indoor mobile platforms are still need to be improved. A stair is the most representative obstacle in indoor circumstances so that if a mobile platform freely negates a stair, this will accelerate various autonomous driving technology researches. To achieve this, a hybrid link mechanism for mobile platforms is suggested in the previous research. The hybrid link mechanism combines a passive revolute joint with an active prismatic joint and as a result, joint position and center of mass can be freely changed appropriately for a given step. In this paper, a prototype of new hybrid link mobile platform for stair climbing is manufactured based on an optimized kinematic design. Basic performance test on a plain surface and staircases are performed successfully, including climbing a stair of a 315(W) × 130(H) with active movement of slide. As the final process, stair climbing algorithm as well as position recognition process are proposed.

R-Mo: A new mobile robotic platform to reduce variations in height and pitch angle on rugged terrain

This paper presents a new mobile robotic platform (R-Mo) which can reduce unexpected variations in height as well as pitch angle of its main body while traversing rough terrains. As a measure for the smooth movement of mobile platform, the variations in height and pitch angle are chosen in this study. Then, the kinematic analysis on the Rocker-Bogie mechanism is carried out to investigate its variations in height and pitch angle on rough terrains. Based on this result, a new mobile platform is systematically designed by combining the Rocker-Bogie with the inverse four bar linkage. The extensive experiments are carried out by using the Rocker-Bogie mechanism and the proposed R-Mo against rough terrain, which validate that in comparison with the Rocker-Bogie mechanism, the average and maximum variations in height of proposed R-Mo are reduced by 12.72% and 5.96%, respectively, and the average and maximum variations in pitch angle of proposed R-Mo are considerably reduced by 65.87 % and 60.53 %, respectively.