Junichi Kurata

Water surface measurement in a shallow channel using the transmitted image of a grating

In this work, the measurement of the depth or shape of a shallow water channel using the transmitted image of a grating is discussed. A noncontact approach, using a simple optical system is described and the angle and depth of the refracting surface may thus be determined. Other applications include simulation of air flow in engineering systems.

Navigation system for a mobile robot with a visual sensor using a fish-eye lens

Various position sensing and navigation systems have been proposed for the autonomous control of mobile robots. Some of these systems have been installed with an omnidirectional visual sensor system that proved very useful in obtaining information on the environment around the mobile robot for position reckoning. In this article, this type of navigation system is discussed. The sensor is composed of one TV camera with a fish-eye lens, using a reference target on a ceiling and hybrid image processing circuits. The position of the robot, with respect to the floor, is calculated by integrating the information obtained from a visual sensor and a gyroscope mounted in the mobile robot, and the use of a simple algorithm based on PTP control for guidance is discussed. An experimental trial showed that the proposed system was both valid and useful for the navigation of an indoor vehicle.

Dynamical locomotion analysis and a model for the peristaltic motion of earthworms

We focus an earthworm peristaltic motion that propagates the receding waves generated by contraction and expansion of arthromeres. This type of motion has the advantage of being flexible for locomotion and can be easily applied to narrow or rough areas. In this paper, peristaltic motion is analyzed from picture images of an earthworm crawling in a straight line. We also examine how to change the length of each arthromere and its diameter, when receding waves propagate the earthworm body. From our experimental results, we model the dynamics of the contractions in the circular and longitudinal muscle as a 2nd-order lag element. As a whole, such locomotive model is proposed that muscle elements are activated by the impulsive input that sequentially propagates a series of arthromeres. It is clear that the experimental results positively represent the proposed model

Path Planning for a Mobile Robot by Integrating Mapped Information

Abstract A method of a path planning for a mobile robot is proposed by using mapped information. Fundamental data on the environment are obtained by using a visual sensor, and several maps based on human factors are created from the environmental information. By integrating these maps, it is possible to plan a path based on the human factors. The algorithm to create each map, the algorithm to obtain the path by integrating all the maps and the experimental results obtained on the vision-based navigation system are discussed. It is expected that this proposed method could applied to a home-service robot.

Optical proximity sensor that uses a laser-scanning system

An optical-sensor scheme that uses a conically scanned laser-beam spot is proposed and discussed. An algorithm for distance and orientation measurements is used together with numerical-analysis techniques to measure distance to an accuracy of +/- 1 mm and orientation to +/- 1.50 degrees . The systems applications for robotic arm manipulators are discussed.

Validation of Performances on Attendant Propelled Wheelchairs with Assisting Control Based on Autonomous Propelling Model

For the demands of assisting and energy saving on attendant propelling wheelchairs, we proposed new controller to generate assisting force when attendant’s force exceeds attendants’ autonomous propelling performance in daily life. On the decision for assisting, the controller has the model of the autonomous propelling activity. For the design of the controller, an attendant-wheelchair model is proposed in this paper and the difference of the performance of the proportional controller and our proposed model based controller were analyzed by simulation. The results shows that the model based controller is superior in terms of cooperation with attendant and energy saving.

DYNAMIC MODELING FOR ATTENDANT PROPELLING WHEELCHAIRS

ABSTRACT The purpose of this study is to establish the model of attendant propelling tasks in order to design for safe and low load attendants propelled wheelchair with assist system. We propose the model of attendants with assumption that attendant and wheelchair is basic motor-load system. The validation of the proposed model identified by experiments shows well corresponding to real attendants propelling behaviour. From the results, the proposed model is used effectively for safe and low load design of assisted wheelchairs.

EVALUATION OF OPERABILITY OF AN ELECTRIC CART HANDLE WITHOUT THE BENDING MOTION OF WRISTS

ABSTRACT Most electric carts employ on oval steering handle mechanism, which is seemed to make operation difficult. When the operator turns the handle, great flexion of wrist joint is observed at both grips, causing distortion of the upper part of the body. As operator moves his upper part to avoid this inconvenience in turning the handle, the center of gravity of the cart and operator is moved to the extreme centrifugal direction. To resolve this problem, we propose a new type of handle, which can be operated with a straight-line motion, without any bending of the wrist joint, a bending torque forced upon wrist joints, a curved shape of upper body and large movement of the center of gravity of cart system. We confirmed that this type of handle was quite comfortable for electric carts by various experimental results.

EVALUATION OF HUMAN MOTOR CHARACTERISTICS IN DRIVING A WHEELCHAIR WITH HAND-RIMS

ABSTRACT A self-propelled type of wheelchair with hand-rims has a good drive assembly that is human operator and offers the convenience of mobility. The wheelchair propulsion of this type, however, causes fatigue to the operator. As a solution of this problem, wheelchairs, which are equipped with a power assist control system, are needed. In this research, the model based on the quantitative human-wheelchair system was proposed for establishing its design manual. The major factor to be considered was the influence of propelling force to the velocity of wheelchair caused by their inertia. The subject participated in a follow-up test in order to adjust the velocity of the wheelchair to the reference velocity. The motor characteristics of operators in driving a wheelchair was described in detailed with results of evaluation by using the special designed test machine.

GUIDANCE OF ELECTRIC WHEELCHAIR BY THE LEAD TYPE OPERATING DEVICE WITH DETECTING RELATIVE POSITION TO ASSISTANCE DOG

ABSTRACT A guidance control method to let an electric wheelchair follow an assistance dog is proposed. In this method, electric wheelchair employs the guidance unit composed of a lead, a winder and two potentiometers. The lead connected to the winder is reeled out or in as the relative position between the assistance dog and the guidance unit is changing. The length and the direction angle of the lead are detected by two potentiometers. Both translational and rotational signals used to control the electric wheelchair are generated by these two detected information. In this report, we described an opinion about an adjustment of the control system by some results of simulated experiment.