Masaya Takasaki

• Saitama University

Recently, touch panels have been used to operate smartphones and personal computers. When touch panels are used to operate devices, somatosensory feedback cannot be enjoyed. This lack of somatosensory feedback increases the reliance on visual feedback to provide a sense of operation. This may reduce device operation performance. Therefore, it is ne...

In a mass measurement system using relay feedback of displacement, an object to be measured was guided mechanically by leaf springs to restrict its motion to a single translation. Such a mechanical guide produces restoring force that affects the estimation of mass based on the measured periods of oscillation. However, such effects on mass measureme...

Recently, fMRI is essential technology for cognitive neuroscience aiming to understand a relationship between brain activity and tactile sensation. However, most measuring instruments and experimental devices cannot be brought in the MRI room because high magnetic field is generated. In this study, to develop a tactile device that can be used in hi...

The characteristics of a differentially-operated optical displacement sensor developed for wind-tunnel using magnetic suspension are studied both analytically and experimentally. The target sensor measures the three-dimensional displacement of the suspended object (floator) from the variations of the shadow of the floator. It is composed of eight o...

DC magnetic suspension operated by transmitted power is introduced to AC magnetic suspension system using magnetic resonant coupling for dynamic stabilization. The traget AC magnetic suspension system has a self-stabilization property. Although restoring force is produced without active control in this system, damping is necessary for dynamic stabi...

A differentially-operated optical displacement sensor was developed for wind-tunnel using magnetic suspension. It utilizes the variation of the floator’s shadow due to the movement of the floator and can measure 3-DoF displacement. This sensor was composed of eight optical systems. Since adjustments by software were necessary, there was variation i...

Previously, an underwater ultrasonic motor with suspended rotor has been reported. The rotor (also called opposing block) has tilted surfaces that imitate impeller. On the other hand, rotation of rotor without the tilted surfaces was observed. The rotor has through holes. In this study, effect of hole shape on rotational characteristics was experim...

A three-degree-of-freedom AC magnetic suspension system using magnetic resonant coupling was fabricated. The AC magnetic suspension system can produce restoring force without active control. This system is dynamically stabilized by adding indirect damping, which is produced by suspending to the stator with viscoelastic support mechanisms. A non-con...

An experimental apparatus is designed for studying the basic characteristics of AC magnetic suspension using magnetic resonant coupling. In finite element analysis, physical properties have been investigated for fabricating the experimental device. Analyses have been conducted for designing the electromagnet actuator. Since the generation of vibrat...

This paper presents the isolation of vibration through the acceleration feedback of the Kalman filter. In this paper, vibration isolation was analyzed both analytically and experimentally through the estimation of the Kalman filter (KF). A negative stiffness mechanism was used to reduce the level of vibration for the developed dynamic system. The t...

A mass measurement system with a relay feedback of velocity has been developed to achieve measurement without gravity. In this system, mass is estimated from the periods of oscillation in the relay-feedback system. Originally, the velocity of the object was solely fed back, which caused the orbit of the object to drift easily. A restoring force com...

Mass measurement using relay feedback of velocity and restoring force compensation is investigated for determining the mass of an object under weightless conditions. In the measurement system, the velocity of the object is fed back through a relay with hysteresis and the force acting on the object is switched from a positive value to a negative val...

A miniaturized force measurement device with zero-compliance mechanism is designed and fabricated using MEMS technology. Zero-compliance mechanism consists of two suspensions connected in series through a detection point. When a force is applied to an object suspended by this mechanism, the position of the object can be kept constant by controlling...

The bellows pneumatic actuator, which is made by folding a non-stretch film, has been proposed for various applications because it is easy to fabricate and is extremely thin and light. However, it has subpar durability performance, especially in the folded part of the film. In this study, we propose an actuator with a pod structure that possesses h...

Click sensation is the feedback by sound and haptic feeling during pressing down an input device such as a button or a switch. In our daily lives, perceiving a click sensation causes us to recognize completion of an operation. Recently, however, input devices using touch screens, such as smartphones, have become widespread, and these devices do not...

Recently, touch screens and physical buttons that can be operated with small amount of force are used to operate information devices. Some of them provide feedback on completing their operation through somatic sensation. An example of that is a button that has a click sensation induced by stiffness change. However, the quantitative evaluation of th...

An interaction through a negative-stiffness spring is introduced into a dual-mass dynamic vibration absorber (DVA) to lower its resonance frequency. DVA is one of the practical vibration control devices. In principles, it consists of an absorption mass and a spring. It can eliminate vibration at a specified frequency that equals the resonance frequ...

A newly developed AC magnetic suspension system is designed and fabricated to investigate the performances. A new concept of design is revealed for operating the apparatus differentially where the floator is kept at a constant position despite changing the parameters of the upper stator electromagnets. An extensive finite element analysis is conduc...

In order to apply soft actuators to extreme environments, the actuators mainly composed of polyimide (PI) was developed. Previous PI film actuators had problems with the life of repeated operation and the difficulty of manufacturing. To solve these problems, a soft actuator was fabricated by using a heat compressed air molding of PI films. By press...

Nowadays, aspiration pneumonia has become one of the most fatal cause of death in Japan. The aspiration pneumonia is mainly caused by dysphagia, however the quantitative evaluation and effective treatmenat have not been developped yet. In the present study, we try to propose a novel method to quantitatively grasp the swallowing state by utilizing m...

A prototype of a soft actuator for extreme environments was fabricated, and driven in a cryogenic temperature environment. Previous soft actuators cannot be used for robots in extreme environments because resin, the main fabrication material, exhibits weak environmental characteristics. Therefore, this study proposes the application of polyimide (P...

A first-order-reset element (FORE) controller is modified to adjust the vibration attenuation characteristic of a magnetic suspension system. The proportional-derivative (PD) feedback control is the simplest control method of stabilizing magnetic suspension systems. In the PD-controlled system, restoring force is produced with the proportional elem...

One of the practical vibration control devices is dynamic vibration absorber (DVA). In principles it consists of an absorption mass and a spring. It can eliminate vibration at a specified frequency that equals the resonant frequency of DVA. To eliminate low frequency vibration, it is necessary to increase the absorption mass or lower the spring con...

A magnetic suspension system using rotational flux-path control mechanism is developed. In the developed fluxpath control mechanism, a pair of gear-shaped flux control plates are attached to the top and bottom of a permanent magnet (magnetic source); they are surrounded by a ferromagnetic outer yoke with teeth facing the control plates. The gear-sh...

Recently, physical buttons that can be operated with a small amount of force are used to operate information devices. Some of them can involve user’s recognition of completing their operation easily. An example of such attempt is the button with nonlinearity in the relationship between stroke and reaction force. There, however, is not enough quanti...

An AC magnetic suspension system operated differentially has been designed and developed to investigate the characteristics of AC magnetic suspension using magnetic resonance coupling. This device enables the floator to keep a constant position despite changing the parameters of the stator electromagnets by differential operation. A permanent magne...

In the assembly of micro components, a slight impact during assembly affects product performance. This work focuses on the assembly of parts including magnetized components. In the assembly of such parts, the attractive force acting between the parts causes a difficulty of assembly without collision. For this reason, such a work is conducted by ski...

The fundamental characteristics and performances of alternating current (AC) magnetic suspension using magnetic resonant coupling are studied analytically and experimentally. Nowadays, wireless power transfer to the suspended object is required during non-contact suspension in some applications. Therefore, magnetic resonant coupling has been introd...

In near-field levitation, an object can be levitated vertically upward above vibrating surface of an ultrasonic transducer. On the other hand, it has been reported that an object can be suspended vertically downward under the vibrating surface in the air. We call this phenomenon ultrasonic suspension. However, there is no detailed explanation about...

A multi-degree-of-freedom zero-compliance mechanism is developed for measuring micro force with a cantilever. The force acting on a tip of the cantilever is usually estimated from the displacement of the tip caused by the force. However, the position and attitude of the tip vary after force acts on the tip from the original ones. To keep them invar...

Accelerometer using zero-compliance mechanism is proposed. The zero-compliance mechanism is a series connection of a positive-stiffness suspension and a negative-stiffness suspension with the same amplitude of stiffness. In the proposed accelerometer, an inertial mass is suspended with this mechanism. Force acting on the inertial mass is proportion...

The insertion of elastic ferromagnetic substance into the gap has been proposed to increase the attractive force of a magnetic suspension for vibration isolation system. The vibration isolation system with a series connection of a positive-stiffness and a negative-stiffness suspensions (zero-compliance vibration isolation system) has been studied e...

An AC magnetic suspension system operated differentially has been designed and developed to investigate the characteristics of AC magnetic suspension using magnetic resonance coupling. This device enables the floator to keep a constant position despite changing the parameters of the stator electromagnets by differential operation. A permanent magne...

A mass measurement system using relay feedback of velocity was developed. In this system, the velocity of the object was fed back through a relay with hysteresis. Although the efficacy of the proposed method has been already confirmed experimentally, it was subject to a drift mainly because only the velocity was fed back. To prevent such a drift, a...

A vibration isolation device with an active dynamic vibration absorber is developed to remove vibration induced by a cryopump. Cryopump is used to make high-vacuum and low-temperature environments for precise measurement. However, it induces vibrations with multiple frequencies, which may deteriorate measurement accuracy. This study focuses on remo...

The stabilization of a magnetic suspension system is achieved by using a low-pass filter (LPF) with a nonlinear integrator without any other element. A proportional-derivative (PD) control is commonly used as the simplest method of stabilizing a magnetic suspension system. Meanwhile, a first-order reset element (FORE) was applied to improve transie...

The principle of a zero-compliance mechanism was used to develop a three-dimensional force measurement instrument. In each axis, the point of force is suspended by a zero-compliance mechanism. A vertical axis force estimation operation imitates the structure of a double series magnetic suspension system. An electromagnet directly controls the movem...

An active dynamic vibration absorber is introduced to a cyropump system achieving ultra-high vacuum and extremely low temperature environments for fine observation and high-accuracy measurement. In a cryopump, a so-called displacer moves reciprocally for alternative adiabatic expansion and exhaust of helium gas. Such a motion induces vibration in t...

A vibration reducing effect of a magnetic suspension system using a first-order-reset element (FORE) in the controller is enhanced by a modified reset function. The proportional-derivative (PD) feedback control is the simplest control method of stabilizing the magnetic suspension systems which consists of two elements. In the PD-controlled systems,...

A 3-degree-of-freedom zero-compliance mechanism is applied to a force measurement device using a cantilever. Force measurement using a cantilever has advantages of high resolution because of the low stiffness of the cantilever. However, it has a problem that the measurement conditions change because the point of force is displaced when force acts o...

In the assembly of micro components, a slight impact during assembly greatly affects product performance. This work focuses on the assembly of parts including magnetized components. In the assembly of such parts, the attractive force acting between the parts causes a difficulty of assembly without collision. For this reason, such a work is conducte...

The world's smallest moon lander (OMOTENASHI) will be launched by NASA's space launch system. The lander impacts to the moon at 100km/h. The landing impact is absorbed by crushable materials and an airbag consisted of an external cover and an air chamber made by polyimide films. However, the coexistence of tough glued strength and lightweight will...

When a ferromagnetic object in a vacuum chamber or a container filled with liquid is suspended magneticaly, it is difficult to measure the displacement of the ferromagnetic object from the outside of the container with an eddy current sensor or an optical sensor. This study proposes to apply sensorless series double magnetic suspension to cope with...

A variable stiffness element made of polyimide (PI) films was developed. The element is composed of laminated PI films and a PI balloon. Variable stiffness is realized by jamming transition. Jamming transition change a state of elements inside a balloon from a fluid to a solid by decreasing the internal pressure of the element, and variable stiffne...

An existing laterally control flux-path mechanism has a seesaw mechanism to move a flux-path control plate. Therefore, the size of the apparatus is rather large. To reduce a size of suspension system, a novel flux-path control mechanism is proposed which adjusts the flux reaching the floator by rotational motion mechanism. The principle of the adju...

People have strong tickling sensation when someone touches sensitive body-parts (e.g., neck, ribs) although such strong tickling sensation is attenuated when they do the same stimulation by themselves. In general, the sense of agency, which is the sense that we are generating or managing actions of our body, is considered to be a key factor of prod...

In general, experimental participants are asked to gaze at a rubber or fake hand when inducing rubber hand illusion (RHI). However, in our previous studies, some experimental participants have reported that the bodily illusion was easily induced if they saw the fake hand, which was moving synchronously with their own hand, in their peripheral visio...

A magnetic suspension system with three flux-path control mechanisms are developed to achieve three-dimensional positioning of the suspended object (floator). In the flux-control mechanism, a ferromagnetic control plate is located in the lateral direction of the magnetic source (permanent magnet). It was shown that the attractive force acting on th...

This paper focuses on compatibility of zero-compliance and zero-power characteristics in a single system. To realize such compatibility, a horizontal zero-compliance system is developed, in which a zero-power controlled voice coil motor is connected with a normal spring (positive stiffness) in series. Since the zero-power control results zero-curre...

Via holes are drilled for interlayer connection in printed circuit boards (PCBs). PCB needs washing process to remove impurities after being drilled. Water remains in via holes in PCB after the process. For removing water, application of focused ultrasonic waves has been proposed. Previously, it has been pointed out that dewatering success rate dep...

This paper exhibits the development of a vibration isolation system using an active dynamic vibration absorber (ADVA) as an accelerometer in a low-frequency range; whereas, it operates as a vibration control device in a high-frequency range. The control signal of the ADVA gives an information of the low-frequency acceleration. At the same time, in...

Force measurement using zero-compliance mechanism is proposed and studied experimentally. A zero-compliance mechanism is composed of two suspensions connected in series; one of them is operated to cancel the deflection of the other so that the total length of the suspension is maintained even if force acts between the ends. In the proposed measurem...

A compact active three-degree-of-freedom magnetic suspension system is fabricated which has a new configuration of magnetic poles. The fabricated magnetic suspension system has a differential structure consisting of an upper and a lower electromagnets. The electromagnet consists of four poles with coils and a single common pole whose opposite plane...

A three-dimensional force measurement instrument is designed and developed by considering the basic principle of zero compliance mechanism. In the proposed system, the point of force and the detection point are connected in series and suspended with leaf springs. One of the suspensions operates to cancel the displacement of the other. If any force...

A basic single-degree-of-freedom magnetic suspension system consists of one floator, one electromagnet and one amplifier. For multi-degrees-of-freedom control, multiple electromagnets and multiple amplifiers are necessary, which increases the cost of total system. As a means of overcoming this problem, parallel magnetic suspension has been proposed...

Reduction of vibration in passively supported lateral directions by varying stiffness control is discussed in a vertically active magnetic suspension system. In the target system, one pair of electromagnets is arranged in differential driving mode to actively control the vertical motion of the floator. Usually the floator is prone to vibrate in the...

A novel force measurement instrument is designed and fabricated to validate multi-dimensional force measurement using zero compliance mechanism. In each axis, there is a point of force and a detection point for zero-compliance force measurement. Both the detection point and the point of force are suspended in series and attached with the base frame...

Cryopump is a vacuum apparatus used in various high-accuracy measurement systems such as those for detecting gravity wave and observing micro motion of molecules. However, the pump induces vibrations with multiple frequencies, which may deteriorate measurement accuracy. To overcome this problem, a vibration isolation apparatus with an active dynami...

Our previous studies found that small particles scattered at the bottom of a water-filled rectangular container form several lines at specific positions when laterally oscillating the container at specific frequencies. A fluid analysis focusing on the fluid behavior at the bottom of container elucidated that the small particles tend to gather at th...

Our previous studies discovered that small particles scattered at the bottom of a water-filled rectangular container align at specific positions when the container is laterally oscillated at specific frequencies. Also, a batch manipulation method of submillimeter-scale small particles was proposed by using this unique phenomenon. In the present stu...

Previously, a tactile display using surface acoustic wave which is a kind of ultrasonic vibration has been developed and can render tactile sensation like roughness. Basic principle is friction reduction induced by the wave and its control. Switching the wave at certain intervals results in vibrations on user's finger surface. To consider realistic...

Our previous studies have proposed active self-touch in which experimental participants can voluntarily touch a fake/virtual body as well as their own body by using a robotic master-salve system when experimentally manipulating sense of body ownership. This paper introduces a novel experimental platform that can control temperature displayed to the...

In this paper, we explained a pneumatic film actuator fabricated by molding process. In our previous research, a bending type actuator have been developed. The bending motion is occurred by pleated structure. The structure is formed by folding process of films. The folding process is performed manually and is complicated. Additionally, the pleated...

A switching stiffness control and a modified variable stiffness control were applied to reduce vibration in the lateral directions in active magnetic suspension system with electromagnets operated in the differential mode. The magnetic suspension system using the attractive force between magnetized bodies is inherently unstable in the normal direct...

A zero-compliance mechanism is fabricated which uses a one-piece parallel spring movement and a voice coil motor to achieve force measurement. The conceptual zero-compliance mechanism is a series connection of a spring with positive stiffness and a spring with negative stiffness whose amplitude is equal to the positive one. When force acting on the...

A new over-flow prevention valve with a trigger mechanism is designed, fabricated and studied experimentally to evaluate its performances. Loading arms are used to transfer combustible fluid such as oil between tankers and tanks. A loading arm is equipped with an over-flow prevention valve for safety. This valve stops the fluid flow when the fluid...

A wind-tunnel system for spinning body has been proposed to measure hydrodynamic forces acting on the body. In the proposed system, the body is suspended and rotated by electromagnets. The forces are measured from the control signal for suspension. In the previously fabricated apparatus, eight electromagnets were placed around a wind-tunnel. An opt...

This paper treats a relay-feedback mass measurement system that uses a relay with hysteresis and feeds back the velocity of the object. The measurement system has an on-off relay with hysteresis and switches force acting on the object in relation to its velocity. Such nonlinear control induces a limit cycle. The mass of the object is determined fro...

Parallel magnetic suspension has been proposed which levitates multiple floators with a single power amplifier. This study applies this concept to a multi-degree-of-freedom system. In such systems, multiple electromagnets are used to stabilize multi-degree-of-freedom motions of the floator. In conventional system, each electromagnet is driven by th...

A novel flux control magnetic suspension system that places control plates beside the magnetic source (permanent magnet) is proposed. In a conventional flux-path control magnetic suspension system, the control plates were inserted between the magnetic source and the suspended object (floator). In contrast, the control plates were placed beside the...

Parallel magnetic suspension that controls multiple floators or multi-degree-of-freedom motions with a single power amplifier has already been realized. This study focuses on zero-power control in a two-degree-of-freedom parallel magnetic suspension system. The zero-power control is achieved by feeding back the integral of the control current. The...

Accelerometer using zero-compliance mechanism is purposed in this paper. This accelerometer is invented to measure long-period and small oscillations such as ground motions and building vibrations with a high resolution. The zero-compliance mechanism is composed of two suspensions with positive stiffness and negative stiffness. Force acting on the...

Many kinds of viscous liquid are used in industrial processes. Viscosity causes resistance to fluid flow. The higher the viscosity of a liquid is, the higher will viscous resistance is. Highly viscous liquid is hard to flow. Several methods are available to control the viscosity of a liquid which has many industrial applications. This study focuses...

Parallel magnetic suspension that controls multiple floators or multi-degree-of-freedom motions with a single power amplifier has already been realized. In this system, all of the suspended points move simultaneously even when a disturbance acts on one of the suspended points solely because all electromagnet’s coils are connected. This paper studie...

Double series magnetic suspension is applied to force measurement. In a double series magnetic suspension system, two floators are suspended with a single electromagnet. When the position of the second floator is regulated, for example by PID control, the second floator is maintained at the original position against an external force acting on it w...

A wind tunnel system for a spinning body was developed for the measurement of the hydrodynamic forces acting on the body. In that system a ferromagnetic sphere (body) was suspended and rotated by electromagnets. The forces acting on the body were measured from the control signal for suspension. However this existing arrangement is not still appropr...

Currently, pumps are used in various fields to supply air and liquid. These pumps include sliding parts and there is a limit of life time due to friction and wear. To solve this problem, a number of pumps using ultrasonic vibration have been proposed. A common feature of ultrasonic pumps is having no sliding parts. Therefore, the life time seems lo...

A new overflow-prevention valve for combustible fluid is developed which uses a trigger mechanism. Loading arms for combustible fluid are used for transferring oil from a tanker to tanks and vice versa. The loading arm has a valve for preventing overflow. Overflow- prevention valves cannot use any electric component to avoid combustion. Therefore,...

Switching stiffness control is applied to attenuate vibration in the lateral directions in an active magnetic suspension system with electromagnets operated in differential mode. The magnetic suspension system using the attractive force between magnetized bodies is inherently unstable in the normal direction so that feedback control is necessary to...

An active vibration isolation system with an active dynamic vibration absorber has been developed where an air actuator is used as a control device in a low-frequency range and a dynamic absorber used as an actuator in a high-frequency range. In this system, acceleration is measured by the dynamic vibration absorber in a low-frequency range and a l...

The controllability and observability of parallel magnetic suspension systems are investigated analytically. A parallel magnetic suspension system has multiple floators and electromagnets driven by a single amplifier. In this paper, the multiplicity is set to an arbitrary counting number n. Parallel systems are classified into four types based on t...

A positioning device for placing a magnetized component on a ferromagnetic plate without collision has been fabricated. When the magnetized component approaches to the plate, the attractive force between them increases sharply as the gap decreases. It sometimes causes them to collide. To prevent such collision, a force compensation control is appli...

Ultrasonic vibration can generally be excited by piezoelectric materials and can propagate in solids coupled to these materials. Some researchers have applied ultrasonic vibration, when excited on solid surfaces, to the realization of tactile displays. Users touch the display surface with a normal direction vibration. The squeeze film effect, which...

A novel alternate-current (AC) magnetic suspension using magnetic resonant coupling is proposed and studied both theoretically and experimentally. An AC magnetic suspension with energy transfer function has been developed to achieve magnetic suspension and energy transfer to the suspended object simultaneously. However, the energy transfer efficien...

Ultrasonic vibration can generally be excited by piezoelectric materials and can propagate in elastic medium coupled to them. Some researchers have applied ultrasonic vibration to realization of tactile displays. Users touch display surface on which the vibtation is excited. Under the touch, the friction between the surface and the user's finger ca...

The controllability of parallel magnetic suspension system with series-connected coils is investigated analytically. A parallel magnetic suspension system has multiple floators and electromagnets driven by a single amplifier. Parallel systems are classified into four types based on the output of the power amplifier and the connection of the coils....