Ho Moon Kim

Inspection Robot for Hanger Cable of Suspension Bridge: Mechanism Design and Analysis

Periodic maintenance of suspension bridge is critical to the safety of the bridge structure. Because most of the load on the bridge is supported by the cables, inspections on main cable or hanger are very important. In this paper, we propose a cable-climbing robot enabling convenient and safe visual inspection of the hanger cable. The robot is comprised of three identical modules assembled 120 ° apart circumferentially on a frame around the cable, and each module has three functional mechanisms, that is, driving, adhesion, and safe landing. The robot is controlled wirelessly by an operator on the ground, though ac power is supplied via a tether cable. In addition, the vision sensor consisting of three cameras provides images taken from three different directions covering the cable and the odometer made with a soft idler wheel locates the robot on the cable. The robot is able to transmit the visual images of the cable surfaces in realtime at a position, while climbing up and down. In this paper, the kinematic and force analysis of the robot is performed and its feasibility is experimentally demonstrated.

Sensing and gait planning of quadruped walking and climbing robot for traversing in complex environment

In this paper, a general study on improving adaptability of quadruped walking and climbing robot in complex environment is presented. First, a sensing system composed of range and gyroscope sensors in a novel arrangement is developed. By combining the sensing signals and the internal state of the robot, the surface geometry of the environment is sufficiently reconstructed in real-time. Secondly, a planning algorithm for the robot to overcome the reconstructed environment is conducted. Based on the reshaped surface, the planning algorithm not only provides the exact body trajectory and foot positions but also the adaptability of the robot in a specific environment. A method to improve the adaptability of the walking and climbing robot is also introduced. Thanks to the adherent ability of the robot, the center of gravity of the robot is allowed to move outside the support polygon to increase the reach-ability of the next swing leg. Finally, the effectiveness of the proposed approach is verified by the performances of the experiments in complex environments using a quadruped walking and climbing robot named MRWALLSPECT IV.

An In-pipe robot with multi-axial differential gear mechanism

This paper presents a mechanism for an in-pipe robot, called MRINSPECT VI (Multifunctional Robotic crawler for In-pipe inspection VI), which is under development for the inspection of gas pipelines with 150mm inside diameter. The mechanism is composed of multi-axial differential gear mechanism, wall pressing one, and driven by single motor. It is designed to adapt to the varying inside geometries of pipelines such as elbows by modulating the velocities of active wheels mechanically without any control effort. In this paper, the design features of the mechanism are detailed and its effectiveness is experimentally validated.

Novel robot mechanism capable of 3D differential driving inside pipelines

In this paper, novel mechanisms for an in-pipe robot are presented. Multi-axial differential gear mechanism is designed to be driven with only single motor at any elbow-pipe without additional control efforts while all three wheels keep driving power. Brake system was added to prevent slip of wheel. Active wall pressing mechanism allows controlling the contact forces. And additional rescue mechanism is designed for emergency situation. Lastly, their effectiveness is experimentally validated.

Caterpillar-based cable climbing robot for inspection of suspension bridge hanger rope

Periodic inspection of a hanger rope is needed for the effective maintenance of suspension bridge. However, it is dangerous for human workers to access the hanger rope and not easy to check the exact state of the hanger rope. In this work we have developed a wheel-based robot that can approach the hanger rope instead of the human worker and carry the inspection device which is able to examine the inside status of the hanger rope. Meanwhile, a wheel-based cable climbing robot may be badly affected by the vibration that is generated while the robot moves on the bumpy surface of the hanger rope. The caterpillar is able to safely drive with the wide contact face on the rough terrain. Accordingly, we developed the caterpillar that can be combined with the developed cable climbing robot. In this paper, the caterpillar is introduced and its performance is compared with the wheel-based cable climbing robot.

Development of cable climbing robot for maintenance of suspension bridges

In this paper, we introduce a wheel-based cable climbing robot system developed for maintenance of the suspension bridges. The robot consists of three parts: a wheel based driving mechanism, adhesion mechanism, and safe landing mechanism. The driving mechanism is a combination of pantograph mechanism, and wheels driven by motors. In addition, we propose a special design of safe landing mechanism which can assure the safety of the robot on the cables when the power is lost. Finally, the proposed robotic system is manufactured and validated in the indoor experimental environments.

Development of Cable Climbing Robotic System for Inspection of Suspension Bridge

In this paper, we propose a wheel-based cable climbing robotic system which can climb up and down the vertical cylindrical cables in the suspension bridges. Firstly, we develop climbing mechanism which includes wheels driven by motors and adhesion system.In addition,we propose a special design of adhesion mechanism which can maintain adhesion force even when the power is lost.Finally, an additional mechanism is developed for guaranteeing the safety of the robot during operations on cables.

Recognition of inside pipeline geometry by using PSD sensors for autonomous navigation

To deploy an untethered robot inside pipelines without any external assistance, it is prerequisite to recognize the pipeline elements such as straight pipeline, elbow, T-branch, and miter. This paper presents a method of recognizing pipeline elements using PSD(Position Sensitive Device) sensors. It is easy to implement, but help us collect accurate information necessary for navigating inside pipelines without heavy computation. The method is composed of three parts, which is the method for distinguishing T-branch and miter, searching the direction in T-branch and elbow, and determining the types of pipeline element, respectively. The design for the PSD sensor suite is presented and the algorithm for recognition procedures are addressed. The sensor suite is implemented in an in-pipe robot, called MRINSPECT VI, and its performances are validated.

Sensing and control of quadruped walking and climbing robot over complex environment

In this paper, we propose a method of sensing outdoor environments for a walking and climbing robot. The proposed method ensures the realtime perception of the surface geometry by integrating a range and a gyroscope with a novel arrangement of the sensors. In addition, a gait planning algorithm based on the sensing method is presented. The algorithm runs fast since it is simple, and the rich information from the sensing system helps the robot overcome the real environment, even an extremely complex one. The sensing system is implemented in a quadruped walking robot, called MRWALLSPECT IV and its effectiveness is proved experimentally.

2-2D differential gear mechanism for robot moving inside pipelines

This paper presents a mechanism for the robot moving inside of pipelines. The mechanism is composed of the 2-2D differential gear mechanism, the active adhesion mechanism, and the rescue mechanism. The 2-2D differential gear mechanism is designed to be driven with single actuator at any elbow type pipelines without any additional control efforts. The active adhesion mechanism is for providing sufficient adhesion forces of the robot on climbing over the pipelines against the gravity. In addition the rescue mechanism is designed for retrieving the robot safely in emergency situation. In this paper, three proposed mechanisms are explained in details and their effectiveness is experimentally demonstrated.