Toshi Takamori

On design of a redundant wire-driven parallel robot WARP manipulator

A redundant wire-driven parallel robot, the WARP manipulator, is a new robot mechanism which is suitable especially for high speed assembling of lightweight objects such as semiconductors. In this paper, a WARP manipulator was designed from the viewpoint of working space by considering conditions that the travelling plate must be abbe to generate arbitrary amounts of force and moment and the wires are not to be in contact. Simulation results of working space proved the validity of the design procedure described. A prototype of WARP manipulator was constructed. The kinematic parameters were calibrated for position control.

Artificial tactile feel display using soft gel actuators

It is difficult for the conventional tactile displays to express fine touch as a surface of cloth. A mechanical device appropriate for minute distributed stimuli on human skin does not exist. This paper proposes a ciliary device using soft high polymer gel actuators (ICPF) as a solution to this problem. This new device can generate various distributed stimuli to human sense receptors. It was experimentally confirmed that, combinations of vibratory stimuli of high frequency and low frequency produced complex tactile feels. Comparison of the artificial tactile feels and cloth material samples demonstrated that this device developed could display subtle distinction in the touch of cloth.

An actuator model of ICPF for robotic applications on the basis of physicochemical hypotheses

The ICPF (ionic conducting polymer gel film) actuator is a new high polymer gel actuator by which revolutionary robotic mechanisms are expected. Actuator models for CAE are essential to the robotic design. However, present black/gray-box models of ICPF cannot express its nonlinear characteristics with enough accuracy. In this paper, a white-box actuator model is proposed on the basis of physicochemical hypotheses on the motion principle which are supported at present. In this model, travel of sodium ions and water molecules in the actuator membrane is modeled. Internal stress is generated by swell and contraction of the gel by water content change, electrostatic force of fixed sulfonic acid groups, and momentum conservation effect. Simulation results show higher accuracy on transient response and nonlinear characteristics in comparison with conventional models.

Linear approximate dynamic model of ICPF (ionic conducting polymer gel film) actuator

The ionic conducting polymer gel film (ICPF) actuator is a perfluorosulfonic acid membrane plated with platinum on its both surfaces. It bends in water and in wet condition by applying a low voltage of 1.5 V to its surfaces. This phenomenon was discovered in 1992. The principle of the motion is still unknown. This paper discusses 2-dimensional linear approximate modelling of the ICPF actuator. The authors are proposing a dynamic model of the actuator consisting of an electrical stage, a stress generation stage and mechanical stage. In the stress generation stage, time derivative of current generates the internal stress with a second degree delay. Expansion and contraction of each surface induce bending motion in the mechanical stage. Simulation results were in agreement with actual responses.

Modeling of Nafion-Pt composite actuators (ICPF) by ionic motion

In this paper, a white-box model of Nafion-Pt composite actuators considering the following physical phenomena is proposed: 1) ionic motion by electric field, 2) water motion by ion-drag, 3) swelling and contraction of the membrane, 4) momentum effect, 5) electrostatic force, and 6) conformation change. Computer simulation showed the following results. 1) The simulated motions agreed with experimental results improving the accuracy in comparison with the conventional models, especially on the time of the maximum displacement. 2) The nonlinear relation between input voltage and the maximum displacement was explained.

A portable parallel manipulator for search and rescue at large-scale urban earthquakes and an identification algorithm for the installation in unstructured environments

Essential points in robotic facilities for search and rescue at large-scale urban earthquakes were investigated. A parallel robot driven by multiple cables is proposed for transfer of debris. It is portable and is assembled rapidly in destroyed houses. An identification algorithm of mechanism parameters peculiar to this portable robot was studied. On the basis of identification error analysis, optimal number of measurement points and the size of an identification reference frame were obtained.

Development of a distributed actuation device consisting of soft gel actuator elements

It is desirable that soft objects like organs are manipulated by soft actuation devices. This paper presents a newly developed device using a large number of actuator elements made of a soft gel material, which applies a distributed driving force on objects. The material used in the device is an ionic conducting polymer gel film and the structure of the elements is elliptical friction drive. Experimental results showed that an object placed on such a device could move at a speed of 0.62 mm/sec. This paper refers also to fundamental experiments and a concept for a more efficient drive.

On motion planning of mobile robots which coexist and cooperate with human

In this paper a motion planning method for mobile robots that coexist and cooperate with human beings to avoid collision is proposed. Human motion, which has large uncertainty, is predicted by a motion predictor using a stochastic process model to generate probability distribution maps of human existence. An evaluating function is defined considering the danger of collision and efficiency of trajectories. A genetic algorithm determines the robot trajectory by optimizing the function. This procedure is repeated for each sampling time. The robot moves maintaining high safety against various possible human motion. Simulation results revealed that robots can reach goals avoiding danger along appropriate trajectories and that this method is effective especially for the case where optimal trajectories dynamically vary according to change of human motion.

Flow and temperature measurement of natural convection in a Hele-Shaw cell using a thermo-sensitive liquid-crystal tracer

The temperature and flow field of natural convection in a Hele-Shaw cell is visualized by using a liquid-crystal tracer. The tracer photographs obtained by this method are compared with the interferograms of previous experiments using the same experimental setup, and the applicability of the present methods is validated. Quantitative data of the temperature and velocity were obtained by applying a colour-image-processing technique to the visualized images.

A new home robot positioning system (HRPS) using IR switched multi ultrasonic sensors

We propose a very fast measuring system for the location of a mobile robot in an indoor environment. The proposed localization method utilizes ultrasonic and infrared signals simultaneously. The transmitter, which is mounted on the mobile robot, transmits both ultrasonic and infrared signals at the same time. The receivers, which are located at fixed points in the ceiling of the room use the received infrared signal as a trigger to measure the time of flight of the ultrasonic signal. The location of the robot is computed by measuring its distance from three receivers. The heading of the robot is computed by measuring its position in two successive points while the robot moves from one point to the other. The performance and validity of this system are evaluated using one transmitter and six receivers located in a 6 m/spl times/4 m room. The positioning error is less than 5 cm.