Mitsutaka Hikita

Robot finger design for myoelectric prosthetic hand and recognition of finger motions via surface EMG

In this paper, robot hand design aiming at application to a myoelectric prosthetic hand and recognition of finger operation via surface EMG are discussed. The robot hand with two fingers, thumb and index finger, was built to implement fundamental motions required in daily life, such as grasping and holding. The fingers are driven by the wire actuation system to imitate the humans tendon mechanism. In order to control each finger of the developed myoelectric prosthetic hand independently, using the neural network, identifier which classifies four finger operations, namely flexion and extension of the thumb in metacarpophalangeal (MP) joint and flexion and extension of the index finger in MP joint, was constructed. The recognition of each finger operation was performed using the four patterns of the neural network based identifiers in which the recognition method of finger operations differs each other, and the results were compared.

A practical approach for recognition of hand gesture and distinction of its singularity

Recognition of the singularity such as the peculiarity or the inexpertness of the unskilled operator is necessary for safe operation. In this paper, based on the surface EMG signals, we propose a gesture recognition method and a novel distinction method of the singularity in operation. In order to evaluate the proposed gesture recognition and singularity distinction methods, experiments were carried out. In the experiment for gesture recognition, the recognition of 6 kinds of hand gestures of a wrist and a finger was performed. In the experiment for singularity distinction, assuming the peculiarity or the inexpertness of the operator, the same gesture was performed quickly as unusual operation, and unusual operation was distinguished from usual operation using the defined index of the singularity.

Bilateral control for omnidirectional bending motion of the DSD forceps teleoperation system with time varying delay

Recently, robotic surgical support systems are in clinical use for minimally invasive surgery. We have developed a multi-DOF robotic forceps manipulator using a novel omnidirectional bending mechanism, and for the developed robotic forceps manipulator, we proposed a passivity based bilateral control that enables motion scaling in both position tracking and force tracking, and guarantees the stability of the teleoperation system in the presence of constant time delay, so far. In this paper, the passivity based bilateral control is improved so as to guarantee the stability of the teleoperation system not only in the presence of the constant time delay but also in the presence of the time varying delay. However, the proposed bilateral control law is applicable only to the one DOF bending motion of the robotic forceps. Therefore, using the change of coordinates, the proposed bilateral control scheme is extended so that it may become applicable to the omnidirectional bending motion of the robotic forceps. In order to verify the effectiveness of the proposed control scheme, experimental works were carried out for the developed robotic forceps.

Rotary motion generated by synthesized circular / elliptic drive with straight-move ultrasonic motors

In order to achieve more complicated movements necessary to a robot, stage of a microscope, etc., we have proposed a new rotation and movement mechanism. Combining the technology of bimorph-type vibrators with synthesization of drive voltage forms, we showed the possibility of achieving not only rotation but also movement simultaneously. The efficiencies vs. drive voltage forms were also illustrated.

Ultrasonic precise distance measurement and movement detection installed in sensor network

Based on similar technique used in millimeter-wave radar, we have proposed a novel ultrasonic measurement method. It provides information of moving objects, and can be installed in sensor network. In the future, these systems will be very useful in care environment to monitor the elderly or sick persons.

Low-loss saw gas sensor with self-temperature-compensation characteristics for sensor network

Novel SAW sensor for gasses and odors has been invented. The structure has self-temperature-compensation characteristics. Sensor network which can monitor hydrogen-gas leakage from future fuel-cell cars and environments for healthcare of old people and in hospitals has been proposed using this technology. However, sensor nodes operate under extreme low-power consumption, which requires dramatic loss reduction for SAW delay-line sensors. We have invented a new low-loss SAW delay line structure keeping the self-temperature-compensation characteristics. We will present experimental results for the former and simulation results for the latter in this paper.

Detection of sleeping and rising in care environment using sound-wave distance-measurement method at upper vocal register of 18–20 kHz

Recently sensor network which connects many sensors via small-scale private wireless network such as ZigBee and Z-Wave has been studied. It will provide home/office-circumstance monitoring, i.e. taking care of old people, preventing crime and maintaining security. We have proposed novel movement detection for the elderly using precise sound / ultra-sound distance measurement without an invasion of privacy. In the previous paper, Tx and Rx transducers transmitted and received 40-kHz ultra-sound CWs. Distance information was obtained by IFFT based on the relative amplitudes and phases of received signals. But due to short wavelength at 40 kHz, sensitivity was a bit high. In this paper, to solve this problem we focus on detection of the elderlys sleeping and rising states by using 18-20-kHz sound waves at upper vocal register. We also developed automatic-measurement system which has function of sensor node and partial function of center node of ZigBee-based sensor network. Fundamental experimental results using the measurement system are illustrated. Comparison between results at 18-20-kHz sound and 40 kHz ultra-sound waves are also presented.

Study on movement detection in care environment using precise ultrasonic distance measurement at 40 kHz installed in sensor network

Sensor network which connects many sensors via small-scale private wireless network such as ZigBee and Z-Wave has been studied all over the world these days. In the future, it will provide home/office-circumstance monitoring, i.e. taking care of old people, preventing crime and maintaining security. In this paper, we have proposed a new care-environment monitoring system using novel ultrasonic distance-measurement and movement-detection method installed in ZigBee-based sensor network. Comparison between our method at 40 kHz and the conventional millimeter-wave radar mounted on high-end vehicles will be illustrated. Developed automatic-measurement system and fundamental experimental results will be presented.

Study on achievement of simultaneous X, Y movements and theta rotation using straight-move ultrasonic vibrators

High-performance machines such as optical microscope and direct drawing machine, etc. require very complicated movements to handle objects. We have proposed a novel ultrasonic motor to achieve both X- and Y-directional movements and theta-angle rotation simultaneously for optical microscope as an example. It has a new structure constructed with straight-move shafts attached to bimorph vibrators. Three shafts, i.e. one unit, are connected perpendicularly to make circular / elliptic / straight micro-motions of shaft tip by driving voltages to bimorphs. Peripheral circuits which supply driving voltages with arbitrary amplitudes and phases have also developed. Combining the circuits and above three units arranged triangle apexes, we have achieved a new ultrasonic motor which drive the stage to move and rotate simultaneously. These technologies can be applied other high-performance machines.

Ultrasonic radar sensor installed in sensor network for care environment — Technique Advanced from millimeter-wave radar

Based on similar technique used in millimeter-wave radar, we have proposed a novel ultrasonic measurement method. It provides information of moving objects, and can be installed in sensor network. In the future, these systems will be very useful in care environment to monitor the elderly or sick persons.