Genki Yamauchi

Volcanic ash observation in active volcano areas using teleoperated mobile robots - Introduction to our robotic-volcano-observation project and field experiments

Observation of an active volcano is very important to determine a strategy for estimating its eruptive activity and providing residents with an evacuation warning. However, it is too dangerous for humans to install cameras during eruptive activity to determine the status of a volcano. Furthermore, permanently installed cameras might be damaged by eruptions, and craters can emerge in unanticipated positions. To handle this situation, we proposed robotic observations in a volcanic area after an eruption using a multi-rotor UAV (unmanned aerial vehicle) and a small ground robot. Field experiments are effective at promoting this type of research and development. Therefore, we performed several field experiments at Mt. Asama. In this paper, we introduce our robotic observation project, and report on the field experiments conducted with teleoperated mobile robots in October 2012 at Mt. Asama.

Development and field test of teleoperated mobile robots for active volcano observation

When an active volcano erupts, a restricted area is typically set according to the eruption level. However, it is very important to observe eruption products inside of this area to predict the timing and scale of volcanic hazards, such as debris flows. Therefore, we propose a robotic observation system for active volcanoes that is composed of a multi-rotor unmanned aerial vehicle (UAV) and a mobile ground robot. To deliver the ground robot safely from the multi-rotor UAV to the ground, we implemented a sky-crane mechanism and confirmed the feasibility of the mechanism theoretically. In this paper, we introduce our volcano observation scenario as well as the observation system and sky-crane mechanism we have developed. Finally, we report on a field test conducted at Mount Asama in September 2013.

Positioning device for outdoor mobile robots using optical sensors and lasers

We propose a novel method for positioning a mobile robot in an outdoor environment using lasers and optical sensors. Position estimation via a noncontact optical method is useful because the information from the wheel odometer and the global positioning system in a mobile robot is unreliable in some situations. Contact optical sensors such as computer mouse are designed to be in contact with a surface and do not function well in strong ambient light conditions. To mitigate the challenges of an outdoor environment, we developed an optical device with a bandpass filter and a pipe to restrict solar light and to detect translation. The use of two devices enables sensing of the mobile robot’s position, including posture. Furthermore, employing a collimated laser beam allows measurements against a surface to be invariable with the distance to the surface. In this paper, we describe motion estimation, device configurations, and several tests for performance evaluation. We also present the experimental positioning results from a vehicle equipped with our optical device on an outdoor path. Finally, we discuss an improvement in postural accuracy by combining an optical device with precise gyroscopes.

Teleoperation of mobile robots using hybrid communication system in unreliable radio communication environments

When an active volcano erupts, it is important to have visual images of the area to be able to forecast debris floods and/or pyroclastic flows. However, restricted zones are usually established within a radius of a few kilometers of the crater because of the direct danger to humans. Therefore, we propose an observation system based on a teleoperated mobile robot that is controlled using radio communication during volcanic activity. To evaluate the system, we conducted field tests using a 3G cellular phone inside certain volcanoes. During the experiments, we faced several dangerous situations where the robot stopped all motion because of the weakness of the 3G signal. To solve this problem, we developed a hybrid communication system with multiple robots that employs two radio communication links. In the proposed system, each robot is controlled via 3G communication signals. However, if any of the robots lose the 3G link, the control signal is relayed by another neighboring robot using a local communication link. In this paper, we explain the system, introduce our newly designed robots, and present results of our operation tests.

Online slip parameter estimation for tracked vehicle odometry on loose slope

In case of volcanic eruption, a robotic volcano exploration for observing restricted areas is expected to judge the evacuation call for inhabitants. An unmanned ground vehicle (UGV) is one possibility to apply to such exploration missions. When a UGV traverses on volcanic fields, a slippage between the vehicle and the terrain occurs. This is because the volcanic environment is covered with loose soil and rocks, and there are many slopes. The slippage causes several problems for UGVs, particularly localization and terrainability. Therefore, in this research, we propose a slip estimation method based on a slip model to apply to slip-compensated odometry for tracked vehicles. First, we propose a slip model for tracked vehicles based on the force acting on a robot on a slope. The proposed slip model has two parameters: a pitch angle dependence and a constant component, and these parameters were identified by indoor slope-traveling experiments. Next, we propose a slip parameter estimation method using a particle filter technique with a velocity measurement sensor, and report on the effectiveness of our method by slope-traveling experiments. The experimental result shows that the accuracy of our position estimation method based on the slip-compensated odometry is improved in comparison with conventional methods by using the slip parameters.

Neonavigation meta-package: 2-D/3-DOF seamless global-local planner for ROS — Development and field test on the representative offshore oil plant

This paper introduces an algorithm and implementation of a new navigation package for ROS. The contribution of this work is to provide a path and motion planner package that is suitable for the complex and narrow environments. The package realizes a 2-D/3-DOF seamless globallocal planner. In this package, collision avoidance frequency can be faster than the conventional one, and planned path is always taking the global goal into account. The new navigation package is released as an open-source software on GitHub. In this paper, the field test results in the representative offshore oil plant, which has narrow corridors with projecting pieces of equipment, are shown.