Norio Inou

Group robots forming a mechanical structure-development of slide motion mechanism and estimation of energy consumption of the structural formation

This study deals with group robots forming a mechanical structure. The group robots consist of identical cellular robots with same mechanical structure and information processing. To realize the group robots in hardware, we propose a slide motion mechanism that supports a large mechanical loading. We report the performance test, and energy consumption required for transformation of the cellular robot under various configurations. This paper also discusses the shortest route with minimum energy in transformation when an initial configuration and a final one are given.

Development of pneumatic cellular robots forming a mechanical structure

This study deals with group robots forming a mechanical structure. In this paper, we address the concrete motion mechanisms of the robots. Each robot has a cubic shape with pneumatic actuators. It rotates with a corner of the robot as an axis. To realize the movement, we propose two kinds of mechanical devices. One is a stabilization mechanism that the pneumatic actuator stably forms an arched shape. The other one is a rotary selective valve for minimizing pneumatic elements. This paper also reports a demonstration of the pneumatic robots in hardware.

Flexible Hermetically-Sealed Mobile Robot for Narrow Spaces Using Hydrostatic Skeleton Driving Mechanism

Almost all of conventional mobile robots for narrow spaces exploration, e.g. rescue robots, adopt crawler or wheel mechanisms. However, in narrow spaces, such robot is often stuck because the robot body is sandwiched between both sides of a terrain. Especially, with normal crawler or wheel mechanisms, it is impossible to penetrate into narrow spaces lower than the height of the robot. In addition, sealing bushes of drive shaft cause unignorable energy loss because of rotational resistances. In order to solve these problems, this study proposes an innovative flexible robot with new hydrostatic skeleton driving mechanism. The main components of the robot are a hermetically-sealed outer cover with looped structure and flexible crawlers with hydrostatic skeleton named HS crawlers. This new robot provides remarkable advantages in narrow spaces as listed below: i) The robot can change its shape adapting to terrain; ii) All ground contact areas of the robot are driven toward the same direction. Thus, the robot is able to penetrate into narrow spaces changing its shape even if the terrain is rather narrower than the size of the robot. This paper describes the mechanisms of the robot and the detail of the HS crawler. Driving force of the HS crawler is discussed with comparison of simulation and experiment. Performance of first prototype robot is verified by experiments of wireless driving and passing narrow space. The prototype robot could pass through a space of 300 mm height, whereas the ordinary height of the robot is 420 mm

Functional Adaptation of Mandibular Bone

This study examined the human mandible from the biomechanical point of view. This chapter covers two subjects: mechanical events that occur in the human mandible during biting, and the basic behavior of the functional adaptation of bone. To estimate mechanical response in the mandible, we proposed an individual modeling method based on X-ray computed tomography (CT) data of the individual that consists of four parts. First, we extracted contour images of the mandibular shape from the X-ray CT data. Second, we made a surface model covered with polygons. Third, we provided an approximate model modified from a standard type of model. Finally, we obtained an individual finite-element model by transforming the approximate model so that it fitted the shape of the surface model. Using the model, we analyzed the stress distribution of the mandible during biting. The stress distributes in the whole area of the mandible, although there are some regions that are highly stressed. The stress distribution was compared with the bone density distribution, and a strong correlation was found. This correlation tells us that the human mandibular bone also has functional adaptation. Based on the analytical results, we discussed the mechanical rationality of the human mandible and the basic behavior of functional adaptation. To examine mechanical rationality, we determined bone robustness by calculating the ratio of stress value to bone strength for every element. The result shows that the human mandible takes a rational structure because the ratio is almost uniform throughout the mandible. To examine the basic behavior of functional adaptation, we proposed a model of functional adaptation and showed that the proposed model self-organizes a proper mechanical structure. We also showed that mechanisms of mandibular deformity can be explained successfully by the proposed model.

Cellular Robots Forming a Mechanical Structure

This paper deals with group robots called CHOBIE that cooperatively transform a mechanical structure. The CHOBIE have slide motion mechanisms with some mechanical constraints for large stiffness even in movement. First of all, a way of structural transformation including the mechanical constraints is discussed. Second, dissipative energy in the structural transformation based on experimental data of the CHOBIE is estimated. Third, for autonomy of the robots, CHOBIE II is developed and the performance test is demonstrated.

Reconfigurable group robots adaptively transforming a mechanical structure - Crawl motion and adaptive transformation with new algorithms

This paper describes group robots adaptively construct a mechanical structure. The feature of the robots is high rigidity by adopting sliding mechanisms. This study discusses algorithms of crawl motion and adaptive construction considering mechanical constraints of the robots. The proposed algorithm is based on local communication of the robots. We introduce a scheme of a temporary leader which is autonomously specified by form of the structure. The scheme decreases amount of information in communication between the robots. The experimental demonstrations are also shown in this paper

Hermetically-sealed flexible mobile robot “MOLOOP” for narrow terrain exploration

Almost all of conventional exploratory robots adopt crawler or wheel mechanisms. However, such robots are often stuck at narrow spaces. This study proposes an innovative flexible mobile robot named “MOLOOP”. This robot consists of a hermetically-sealed outer cover with double-looped structure. The robot is driven by original flexible crawlers which are composed of multiple flexible bags with loop connection. Since the whole body of the robot is quite flexible, the body can change its shape adaptively according to the terrain. However, the performances of the previous prototype are not enough in terms of the speed and the size. This report describes the performance improvement of MOLOOP aiming speed-up and miniaturization. For the purpose of using high input pressure, this study reinforces the flexible bags of the crawler by fibrous materials. This improvement contributes not only the power of the crawler but also downsizing. The new HS crawler improves the torque and speed from 0.23 Nm to 3.43 Nm and from 3.0 mm/s to 39.0 mm/s respectively. The new prototype of MOLOOP with the new crawler achieves downsizing from 370 mm to 275 mm in the width. The speed is also increased from 3.0 mm/s to 9.0 mm/s. The prototype robot successfully passed through a space with 230 mm height which is narrower than the robot width (275 mm). For the purpose of shock resistance test, we dropped the robot from 1.5 m height to a hard floor. After that, it moved without any problems.

Three-dimensional Display System of Individual Mandibular Movement

It is expected to develop an intelligible diagnostic system of temporomandibular disorders (TMD) for both medical doctors and patients. This study proposes a display system that visualizes motion of the human mandible. The system integrates two engineering methods. One is an optical motion capture technique for measuring the mandibular movements. The other is an individual modeling method based on the X-ray CT data. It is important to know exact mandibular movements for the proper diagnosis. This paper discusses experimental verification of the total performance of the system using a device of hinge movement. The verification clearly shows that precision of the model has a great effect on accuracy of the movements. The total performance of the system is achieved within an accuracy of 0.2mm at the hinge of the device. The system provides not only three-dimensional visual information of the mandibular movements as animations but also quantitative information of position, velocity and acceleration at an arbitral point of the model. The system will be useful for informed consent in medical treatments of TMD.

Patient Specific Finite Element Modeling of a Human Skull

This paper presents automated finite element modeling method and application to a biomechanical study. The modeling method produces a finite element model based on the multi-sliced image data adaptively controlling the element size according to complexity of local bony shape. The method realizes a compact and precise finite element model with a desired total number of nodal points. This paper challenges to apply this method to a human skull because of its intricate structure. To accomplish the application of the human skull, we analyze characteristics of bony shape for a mandible and a skull. Using the analytical results, we demonstrate that the proposed modeling method successfully generates a precise finite element model of the skull with fine structures.

Estimation Of Masticatory Forces ForPatient-specific Analysis Of The Human Mandible

This paper proposes an estimation method of the masticatory forces using an objective function composed of three criteria: efficiency of muscular activities, moment balance between muscular and biting forces, and reaction forces at condyles. The method is applied to a patient whose jaw has a severe deformity, and the influence of the criteria is examined. The muscular forces of the numerical result with the consideration of the all three criteria well agree to the analysis of EMG signals. Individual stress analysis under the estimated mechanical condition is also performed. There is no stress concentration and little difference in stress distribution on both left and right sides in spite of the asymmetrical mandibular shape and masticatory condition. The numerical result suggests mechanical adaptation of mandible by the masticatory forces.