The differential drive mechanism, which is one of the mechanisms of wheeled mobile robots, is simple and useful for the motion of the mobile robot. The mechanism, however, has typical disadvantages of losing mobility, falling down, etc. when the robot moves over obstacles or uneven terrains. A novel suspension mechanism presented in this paper was designed to help the robot to overcome these problems. In particular, this mechanism is very suitable for a tall robot, which is susceptible to overturning because of the disturbance caused by acceleration, deceleration, and collision. The proposed mechanism called a Multilayered Suspension Mechanism is composed of the effective and well-directed combination of springs and dampers. It is very simple and cost-effective since it has no actuator for suspension. In this paper, mechanical construction and characteristics of the mechanism are described. Then, excellence and performance of the proposed mechanism are demonstrated by simulations and experiments.

In this paper, we present an autonomous in-pipe robot navigating system using vision-based landmark recognition. We propose to use special features of the pipelines (such as elbows or branches) as landmarks by recognizing the shadows of the elbows and branches. To obtain consistent shadow images, the in-pipe robot equips with specially designed illuminator. By analyzing the shadow, the robot can easily identify these landmarks, detect the direction of the passage, and adaptively traverse through while continuously updating the map. The effectiveness of the proposed method is verified by real experiments using the in-pipe robot MRINSPECT V for inspecting inside of the miniature urban 8-inch gas pipeline structure.

In this paper we present an in-pipe robot, called MRINSPECT V (Multifunctional Robotic crawler for In-pipe inSPECTion V), which is under development for the inspection of pipelines with a nominal 8-inch inside diameter. To travel freely in every pipeline element, the robot adopts a differential driving mechanism that we have developed. Furthermore, by introducing clutches in transmitting driving power to the wheels, MRINSPECT V is able to select the suitable driving method according to the shape of the pipeline and save the energy to drive in pipelines. The robot aiming for autonomous navigation is configured with four modules serially connected. Two active driving modules are located in front and rear of the system, respectively. Passive modules are linked between the driving modules. This module-based robot can fit to narrow and winding pipelines by using the novel mechanism such as the specially designed module-joints. In this paper, the critical points in the design and construction of the proposed robot are described with the preliminary results of experiments that yield good mobility and increased efficiency.