Takefumi Kanda

A Bending Pneumatic Rubber Actuator Realizing Soft-bodied Manta Swimming Robot

This paper shows a new design and prototyping method for a bending pneumatic rubber actuator and its application to a soft-bodied manta swimming robot. The design is based on optimal design using non-linear finite element method, in which geometrical and material non-linearity are considered and fabrication process is based on a rapid and efficient prototyping system using a CAD/CAM based rubber molding process. In this paper, the characteristics of several possible actuators are analyzed and evaluated to lead to an optimal actuator design. The actuator works very well with smooth and soft motion. The manta swimming robot in which the developed actuators are embedded is also designed based on non-linear finite element method. The developed manta swimming robot is made only of rubber and it swims in water smoothly as if it was a living fish. The experimental results of the manta robot motion show that good agreement with those of analytical results.

Single Process to Deposit Lead Zirconate Titanate (PZT) Thin Film by a Hydrothermal Method

The hydrothermal method to deposit lead zirconate titanate (PZT) thin film is a new method reported by Tsurumi et al.. in 1991. This method consists of two linked processes. We have found that the film deposited by the first process is not PZT but separated lead zirconate (PZ) and lead titanate (PT). In this paper, we report that a PZT thin film was successfully deposited by a single process. The chemical construction and composition of the film were analyzed. The Zr/(Zr+Ti) ratio of the PZT film was controlled by changing the ionic composition of the solution.

A flat type touch probe sensor using PZT thin film vibrator

Abstract We fabricated a touch probe sensor, having a flat configuration and using a PZT thin film vibrator. This sensor is intended for use in high-precision surface shape measuring tools at low contact force, for example, scanning probe microscopes (SPMs). The sensor consists of an oscillator vibrating in the longitudinal direction. According to our calculations higher sensitivity can be obtained by using longitudinal vibration than by using bending vibration. The vibration was excited and detected by a hydrothermally deposited PZT thin film device. The length of the vibrator was 9.8 mm, and its resonance frequency was 304.35 kHz. When the driving voltage was 3 V p–p at the resonance frequency, the vibration amplitude at the tip of the sensor was 126 nm o–p . We used the flat configuration and miniaturized the oscillator to increase the quantity ratio of piezo film in comparison to the base material, thus improving the sensitivity. The sensitivity and the resolution were evaluated experimentally, with the vertical resolution estimated to be 2.4 nm. This sensor device will be effective for use in high-speed and high-resolution surface shape measuring tools without damage to nano scale construction.

Performance of hydrothermal PZT film on high intensity operation

Hydrothermally deposited PZT film transducers were examined for large vibration amplitude level at resonance frequency. It was demonstrated that the hydrothermal PZT film has superior performance in terms of linearity and maximum vibration velocity. The linearity of frequency response around resonance was excellent and superior than bulk material up to high intensity operation. The maximum vibration velocity of a flexural transducer was 1.3 m/sec. Concerning a longitudinal transducer, two deposition processes were tried. The maximum vibration velocities were 0.53 m/sec and 0.9 m/sec. These values were almost two times larger than bulk PZT materials for high power applications.

New pneumatic rubber actuators to assist colonoscope insertion

Inserting an endoscope into colon requires very technical procedure and it is difficult in some cases even for experienced doctors. Although active colonoscopes have been researched, these instruments are still in the development stage. Mechanisms for this application are required to be soft enough not to injure the colon wall and being deformable enough to adapt to the curves of the colon. In addition, the mechanisms must generate distributed force adequate for traveling. These requirements are difficult to be satisfied using conventional mechanisms and actuators. We have designed and developed two types of new driving mechanism using pneumatic rubber actuators and made their feasibility tests. One mechanism is thin tube wave generator: introducing pulse pneumatic flows to a thin rubber tube causes traveling deformation waves on the tube surface, which drives an object placed on the tube. The other mechanism is round bubbler: a rubber tube which has four chambers in it is wound around the colonoscope to cause traveling deformation waves on the scope surface by sending pneumatic pressures to each chamber sequentially. In this paper, first, we discuss the driving mechanisms, pneumatic control systems, and basic characteristics of these two mechanisms. Then, based on the basic experimental discussions, we fabricated special rubber mechanisms to fit around a conventional colonoscope, and conducted insertion experiments using an intestinum model and an existing colonoscope under various conditions. The experimental results are very promising

A Cylindrical Micro-Ultrasonic Motor Using Micromachined Bulk Piezoelectric Vibrator with Glass Case

A cylindrical piezoelectric vibrator 0.8 mm in diameter was fabricated by micromachining. In this paper, a micro ultrasonic motor 1.8 mm in casing diameter that uses this micro-machined cylindrical bulk piezoelectric vibrator is introduced. This motor consists of the piezoelectric vibrator, a glass case, a bearing, and a rotor. The vibration velocity of the cylindrical vibrator was 715 mm/s when the driving frequency was 69 kHz and the driving voltage was 40 Vp–p. Since the stator transducer is fixed at the end of the cylinder, it is easy to support the vibrator, and the motor has a simple structure. In addition, the vibrator and rotor were supported by glass case. As the case was made of glass, a suitable vibration mode of the driving of the motor was obtained. We have fabricated and evaluated the cylindrically shaped traveling micro-ultrasonic motor using this vibrator.

Elastic Pectoral Fin Actuators for Biomimetic Underwater Vehicles

This paper describes the development of two new types of pectoral fins made of elastic materials. The fins were designed to have flexibility and multifunctionality for use not only as propulsive devices in biomimetic underwater vehicles but in other applications such as grippers, thus avoiding the environmental damage often caused by rigid fins. We developed an actively controlled pneumatic fin and a passively controlled flexible fin.

A mobile jack robot for rescue operation

This paper reports a research and development of a rescue robot using a high-pressure hydraulic actuator. We developed a practical and simple rescue robot, which used a high-pressure hydraulic actuator which generates 100 kN force at 70 MPa to drive a mechanism of jack. The objective of the robot is to jack up debris to keep or to make space of moving courses for other rescue robots and rescue tools, and to rescue victims under debris. The robot jacks up to 33 kN load. We demonstrated that the robot can jack up over 20 kN to jack up a fallen tree of 20 kN.

Development of intelligent McKibben actuator

The aim of this study is to develop an intelligent McKibben actuator with an integrated soft displacement sensor inside, so that displacement of this actuator can be controlled without having any extra devices attached. In addition, the high compliance which is a positive feature of the McKibben actuator is still conserved. This paper consists of four main parts. First of all, different types of soft displacement sensors made out of rubber were composed, and tested for their functional characteristics. Secondly, the intelligent McKibben actuator was developed with the soft displacement sensor incorporated within. Then, experiments of the position servo control with a single intelligent McKibben actuator were carried out. At last a robot arm mechanism was designed with two intelligent McKibben actuators, and those experimental results showed a great potential for its future applications.

Vibration Velocity Limitation of Transducer Using Titanium-Based Hydrothermal Lead Zirconate Titanate Thick Film

High-intensity vibration operation of a titanium based lead zirconate titanate (PZT) thick film longitudinal vibrator fabricated using a hydrothermal method is described in this paper. Higher limitation of vibration velocity is very important for high output power actuators. For sensors, linearity of the frequency response is an important factor. To investigate the performance of the PZT film material, we changed the deposition process of the hydrothermal method and increased the thickness of the PZT film. As a result, the maximum vibration velocity of the longitudinal vibrator was 2.5 m/s (0 to peak value). This value was almost 3-fold that of bulk PZT material. The vibration velocity was limited by the value of maximum stress. The maximum stress of the hydrothermal PZT transducer was larger than that of the bulk PZT transducer. At such high-intensity vibration of over 2 m/s or driving voltage of 150 Vp-p, the frequency response curves were not linear and the jumping phenomenon was observed.