Tomonari Yamamoto

A high-speed locomotion mechanism using pneumatic hollow-shaft actuators for in-pipe robots

This study proposes a high-speed locomotion mechanism for a pipe-inspection robot. As a result of the narrow and complex structures of pipeline networks, it is difficult for robots to move quickly within the pipes. The new pneumatic mechanism proposed here realizes high-speed locomotion along with advantageous features for pipe inspection including a small diameter, flexibility, and low weight. First, we present the design concept of the novel locomotion mechanism using pneumatic flexible hollow-shaft actuators, which was previously developed by the authors. The prototype constructed to realize this concept and the associated mathematical model are then introduced. Second, the basic characteristics of the proposed mechanism are evaluated in terms of the holding force (generated by an expansion mechanism against the pipe wall) and the impellent force that induces forward motion in the robot. Finally, the in-pipe movement performance is confirmed. The experimental results show that the designed robot can be propelled inside a 53-mm-diameter pipe at a maximum speed of 250 mm/s, which is exceedingly faster than conventional designs.

Two axes orthogonal drive transmission for omnidirectional crawler with surface contact

In this paper, we propose an omnidirectional mobile mechanism with surface contact. This mechanism is expected to perform on rough terrain and weak ground at disaster sites. In the discussion on the drive mechanism, we explain how a two axes orthogonal drive transmission system is important and we propose a principle drive mechanism for omnidirectional motion. In addition, we demonstrated that the proposed drive mechanism has potential for omnidirectional movement on rough ground by conducting experiments with prototypes.

A self-locking-type expansion mechanism to achieve high holding force and pipe-passing capability for a pneumatic in-pipe robot

This study proposes a self-locking-type expansion mechanism for in-pipe robots. Previously, we proposed a highspeed locomotion mechanism using pneumatic hollow-shaft actuators; however, this mechanism lacked holding force and could not pass through a bent pipe. The proposed mechanism generates a large holding force and can easily pass through a bent pipe by invoking a self-locking phenomenon. We conceptualize and design the novel expansion mechanism and introduce its associated mathematical model to formulate the holding force and mechanism design. The characteristics and capabilities of the mechanism are elucidated by experiments. From the experimental results, we optimize the applied pressure and the design of the mechanism. The proposed mechanism generates a maximum holding force of 69.7 N, which is 5.2 times higher than that of the previous mechanism, and drastically improves the robots bent-pipe-passing capability. Finally, the performance of this mechanism is confirmed in a simulated pipe test. In this trial, a robot equipped with the proposed mechanism smoothly and steadily moves through complex pipe configurations, including the vertical and bent pipes.

Use of active scope camera in the Kumamoto Earthquake to investigate collapsed houses

The Kumamoto Earthquake occurred in April 2016. We conducted an investigation using the active scope camera to examine the interiors of the collapsed houses. The robot video scope can move by itself to probe narrow gaps. We could safely gather information by inserting it inside houses. We further considered the future possible improvements to the robot based on the investigation. We also determined the constraints to be considered for the robot operation in disaster areas. In addition, we created a test field imitating the features of collapsed houses. We used this field to evaluate our robot mobility and related technologies that are being developed for future applications.