Hidemi Hosokai

Rubber gas actuator driven by hydrogen storage alloy for in-pipe inspection mobile robot with flexible structure

The authors describe rubber actuators using a hydrogen storage alloy for an in-pipe inspection robot, which is capable of moving inside pipelines with inner diameter as small as 2 in. Rubber actuators with both stretching and shrinking capability are shown for realization of such a robot. The proposed robot uses twelve actuators, including six kinds of independently controlled actuators, so that it si more flexible and adaptable in motion: it can move in an inchworm mode through pipelines, it is adaptive for changing pipe diameters, and it is able to pass over the L- and T-joints of pipelines. The robot actuators can initially be achieved and prepared by hydrogen gas. The control method is also shown, with a T-joint movement as an example.<<ETX>>

Cell Structured robotic system CEBOT: Control, planning and communication methods

Abstract The Cell Structured Robotic System CEBOT is a realization of a new class of Dynamically Reconfigurable Robotic Systems (DRRS). The modular cell structure allows unique features like dynamically reconfigurable structure, distributed intelligence, self-repairing capability, fault-tolerance, and applicability in hostile and restricted environments. We propose a concept, cell types and construction, control and sensor system structure, structure planning and communication methods for the advanced series II CEBOT.

Distributed type of actuators by shape memory alloy and its application to underwater mobile robotic mechanism

The basic idea of a new type of actuator based on a shape memory alloy (SMA) and its application to underwater mobile robots are presented. The actuator consists of a multimode SMA, so that any shape can be produced as the synthesized sum of excited modes. Thus, the actuator shows the characteristics of distributed-parameter-type actuators with a specified number of modes. A flat-belt-type SMA is employed, and its bending characteristics are examined. A method of waveform synthesis is presented. Applying the proposed distributed actuators to the underwater mobile robot, a fish-fin-like mechanism is shown to obtain thrust forces in the water. The shape of the actuator was shown experimentally to be similar to the computed shape. As a result, the distributed actuator shows the possibility of application to distributed-parameter shape control.<<ETX>>

Autonomous pipeline inspection and maintenance robot with inch worm mobile mechanism

A new type of mobile robots with the inch worm mechanism is presented in this paper for inspecting pipelines from the outside of pipe surfaces under hostile environments. This robot, Mark III, is made after the successful investigation of the prototypes, Mark I and II, which can pass over obstacles on pipelines, such as flanges and T-joints and others. Newly developed robot, Mark III, can move vertically along the pipeline and move to the adjacent pipeline for the inspection. The sensors, infra ray proximity sensor and ultra sonic sensors and others, are installed to detect these obstacles and can move autonomously controlled by the microprocessor. The control method of this robot can be carried out by the dual control mode proposed in this paper.

Cooperative route-searching behavior of multi-robot system using hello-call communication

Deals with a computer simulation study of the cooperative behavior of multirobots for investigating the characteristics of swarm intelligence generated by multirobot system. Individual robots in the multirobot system are equipped with low-level intelligence to detect obstacles, steer, proceed, and undertake a hello-call communication. This paper first clarifies the characteristics of multirobot behavior under free traveling without hello-call communication and then the characteristics of hello-call communication with respect to message transmission power over whole member robots. Introducing a marker robot to the multi-robot system, the authors find that the multirobot system can generate a communication chain to be used for searching the route to their goal. They demonstrate the swarm intelligence of the multirobots system in the case of route-searching and show the effects of robot population on the swarm intelligence.

Stable contact force control of a link manipulator with collision phenomena

A methodology using the Lyapunov direct method is proposed to analyze the stability of a one-link manipulator system which is positioned on a flexible wall with collision phenomenon. Experimental results of collision control are included. As collision is a phenomenon with energy loss, it is considered to have a stabilizing effect to a system which includes collision. However, from the point of view of robotics, a controlled system shows poor controllability, if collision occurs. The authors have adopted a Herz-type model with energy loss parameter to express the impact force between the manipulator and the wall. Using this model, they prove the stabilizing effect of collision using the Lyapunov method. An experiment was also carried out to show the possibility of stable control including collision using sensor-based force control. As a result, the stable contact control of the manipulator on the flexible object is assured.<<ETX>>

Autonomous plant maintenance robot (mechanism of Mark IV and its actuator characteristics)

Deals with the new mechanism of a maintenance robot, Mark IV. The Mark IV has a mechanism capable of inspecting surfaces of storage tanks as well as pipeline outer surfaces. The main features of Mark IV are as follows: (i) the robot has a multi-joint structure, so that it has better adaptabilities to surface curvatures of pipelines and storage tanks; (ii) the joint of the robot has shape memory alloy actuators to make the robot lighter in weight; (iii) the robot has suckers at both ends of arm, so that the robot can climb up along the wall from the ground; and (iv) a robot with the inch worm mechanism has many functional motions, such that it can pass over flanges and T-joints, and transfer to adjacent pipelines with a wider range of pipe diameters. Thus, the functional level of the maintenance robot has greatly been improved by the introduction of the Mark IV robot.<<ETX>>

Mechanism and control of mobile pipeline maintenance robot with lazy tongs mechanism

A new type of mobile pipeline maintenance robot has been designed to clarify the feasibility of lazy tongs mechanism for adaptation to various size pipelines. The robot basically consists of three modules with two joints between modules and can move straight and spirally along the surface of pipeline. The robot can change its arm length in order to move on the pipeline of various size from 25 A to 100 A, and pass over obstacles such as reducer, diffuser, flange and other plant equipment. The control of the robot is so complicated that the modified dual control mode is introduced using the coordinate transformation matrix. By calculating the position and attitude of the robot under the control mode, the manoeuvrability of passing over a reducer is shown with experimental results.

Parallel-link robot for pipe inspection

In air conditioning equipment, it is very important to diagnose in-pipe corrosion for preventing various troubles such as water leakage, deterioration of performance and so on. We have been developing a pipe diagnostic system for decreasing the time and workload of the inspection and improving the accuracy of the diagnosis, especially a pipe thickness measuring robot with ultrasonic probe which can conduct inspections from outside of the pipe. Existing inspection robots using ultrasonic probes are not suitable for measuring the entire surface of pipes because they use rails fixed to the pipe for scanning, or even if they have unfixed rails and can move along the pipe, they cannot measure joints such as elbow. Therefore, we propose a new pipe inspection robot with parallel-link mechanism, which has a circular rail for scanning the ultrasonic probe, a manipulator for setting the rail and a mobile robot for moving along the pipes. The manipulator and the mobile robot are constructed with the parallel-link mechanism. The feature of this robot is that it can pass elbows and so can measure every section of them. In this paper, we describe the robot mechanism and control method, and the results of experiments with the robot.

Path planning expert system for pipeline inspection robots

The authors discuss sensing planning based on system knowledge for pipeline inspection and intelligent control of a maintenance robot. The pipeline inspection robot can carry out inspection tasks to detect the malfunction location autonomously in a plant pipeline system. It can estimate and search failure causes. The path planning system is shown to find the optimal path for the robot from one point to another under specified criteria. Furthermore, the sensors, for example, infrared ray proximity sensors or ultrasonic sensors, are installed to detect obstacles such as flanges and T-joints, and the robot can move autonomously under microprocessor control. Using PRES (path planning expert system) and SPES (sensing planning expert system), the robot becomes intelligent enough to carry out given inspection tasks automatically.<<ETX>>