Sungmoo Ryew

Robotic system with active steering capability for internal inspection of urban gas pipelines

In this paper, we present a robotic system for inpipe inspection of underground urban gas pipelines. This robot is developed on the purpose of being utilized as a mobile platform for visual and Non-Destructive Testing (NDT) of the pipeline networks. The robot is configured as an articulated structure-like a snake with a tether cable. Two active driving vehicles are located in front and rear of the system, respectively. Passive modules such as a control module and other optional modules are linked between the active vehicles. It has several characteristic features superior to the others such as flexible wheeled leg mechanisms, a steering mechanism with compliance control. Especially the steering mechanism called Double Active Universal Joint (DAUJ) intrinsically prevents rolling of the robot along the driving direction and enables to control its compliance. Those features provide the robot with excellent mobility inside the highly constrained space while negotiating the complicated configurations of the pipeline networks. We outline the construction of the robot and describe its characteristic features.

Biomimetic soft actuator: design, modeling, control, and applications

A new biomimetic linear actuator named Antagonistically Driven Linear Actuator (ANTLA) that could be directly employed in both macro and microscale of robotic applications is introduced in the present work. The presented actuator provides cost effectiveness and simple fabrication process thanks to its plain construction. In addition to producing basic bidirectional rectilinear motions, the actuator is able to modulate its compliance that might be one of the critical elements of the actuator functionality for the biomimetic applications. For the test, the proposed actuator concept is fabricated and assembled in a microscale robot that generates annelid motion.

In-pipe inspection robot system with active steering mechanism

We present a robot system for in-pipe inspection of underground urban gas pipelines. The robot is configured as an articulated structure like a snake with a tether cable. Two active driving vehicles are located in front and rear of the system, and passive modules such as a control module are chained between the active vehicles. The proposed robot has outstanding mobility offered by a new steering mechanism, called double active universal joint, which makes it possible to cope with complicated configurations of underground pipelines. Characteristic features of the system are described and the construction of the system is briefly outlined.

Self-contained wall-climbing robot with closed link mechanism

A self-contained wall climbing robot, called MRWALLSPECT (Multi-functional Robot for WALL inSPECTion) II, is developed. It is designed for scanning external surfaces of gas or oil tanks with small curvature in order to find defects. The robot contains all the components for navigation in itself without any external tether cable. Although it takes the basic structure of the sliding body mechanism, the robot has its original characteristic features in the kinematic design with closed link mechanism, which is enabled by adopting a simple and robust gait pattern mimicking a biological system. By employing the proposed link mechanism, the number of actuators is reduced and high force-to-weight ratio is achieved. This paper describes its mechanism design and the overall features including hardware and software components. Also, the preliminary results of experiments are given for evaluating its performances.

Actively steerable in-pipe inspection robots for underground urban gas pipelines

We introduce the robots called MRINSPECT (multifunctional robotic crawler for inpipe inspection) III and IV which are under development for the inspection of urban gas pipelines. The proposed robots can freely move along the basic configuration of pipelines, such as horizontal or vertical pipelines. Moreover, it can travel along reducers, elbows, and steer in the branches by using steering mechanisms. Especially, their three dimensional steering capability provides outstanding mobility in navigation that is a prerequisite characteristic in urban gas pipelines. Their critical points in the design and construction are introduced with preliminary results of experiments.

Soft actuator for robotic applications based on dielectric elastomer: quasi-static analysis

In this paper a new soft actuator based on dielectric elastomer is proposed. The actuator, called an antagonistically-driven linear actuator (ANTLA), has the muscle-like characteristics capable of performing the motions such as forward/backward/controllable compliance. Due to its simplicity of configuration and ease of fabrication, it has the advantage to be scale-independently implemented in meso- or micro-scale robotic applications. Its basic concepts are introduced and a quasi-static analysis is performed with experimental verifications.

Double active universal joint (DAUJ): robotic joint mechanism for human-like motions

We present a robotic joint mechanism that makes it possible to mimic the human-like motions. The proposed robotic joint, called the double active universal joint (DAUJ), generates a two-degree of freedom motion suppressing rolling by the coupled motions of two independent motors. The mechanism design and kinematics are mentioned. Two application examples are outlined: an anthropomorphic finger and an in-pipe inspection robot. The results of basic experiments are reported to confirm the effectiveness of the proposed mechanism. Also, we briefly introduce the advantage that the compliance of the proposed mechanism can be easily controlled by modulating the engagement period of the magnetic clutch.

A wall climbing robot with closed link mechanism

A compact and robust wall climbing robot, called MRWALLSPECT, has been developed. The robot is designed for scanning external surfaces of gas or oil tanks and inspecting defects with nondestructive testing tools during navigation. It accomplishes fundamental three-degree-of-freedom locomotion such as translation and rotation over the wall with a novel closed link mechanism that we have originally devised. Its design and implementation issues are discussed and the results of tests are addressed.

Soft actuator for robotic applications based on dielectric elastomer: dynamic analysis and applications

In this paper a new soft actuator based on dielectric elastomer is proposed. The actuator, called an antagonistically-driven linear actuator (ANTLA), has the muscle-like characteristics capable of performing the motions such as forward/backward/controllable compliance. In this paper, its dynamic analysis is performed with experimental verifications, and applications for robotic actuating devices are introduced.

Microrobot actuated by soft actuators based on dielectric elastomer

In this paper a microrobot, mimicking annelid animals like the earthworm, is presented. The robot is composed of several ring-like segments. Each segment is able to generate three degree-of-freedom motions such as pan/tilt/up-down respectively, and it is actuated by three soft actuators located equidistantly along the circumferential direction. The soft actuator, called antagonistically-driven linear actuator (ANTLA), is based on polymer dielectrics and has muscle-like characteristics capable of performing motions such as forward/backward/controllable compliance. In this paper, the basic concept of the actuator is briefly reviewed and the robot, including the ring-like segment, is explained in detail with demonstrations.