Surface Acoustic Wave Linear Motor Research Articles

Solid-driven mechanism and experimental study based on surface acoustic wave microfluidic

This study proposes a method to drive a solid by liquid–solid coupling and designs and manufactures a surface acoustic wave actuator to drive a wetted solid ball. The solid ball moves under surface acoustic wave microfluidic acoustic streaming. By theoretical analysis and experimental testing, the driving model is systematically examined in terms of the influence of the device frequency, input power, droplet viscosity, and other parameters on the movement of the ball. The speed at the mark end of the ball under 4.17 W of input power and driving at 60-MHz frequency in pure water reaches 0.175 m/s. Compared with the driving method of a surface acoustic wave linear motor, this wetted solid-driven method easily ensures that the solid ball drives to reach the same order of speed, avoiding numerous problems present in the existing surface acoustic wave linear motors. The proposed method provides important guidance and is of practical significance for the application of surface acoustic wave technology in micromotors and micromanipulation.

Modelling and Finite Element Simulation of a Surface Acoustic Wave Driven Linear Motor

The paper presents modeling and finite element simulation of a surface acoustic wave (SAW) linear motor. A SAW linear motor works on the principle of friction drive provided by SAW propagating on a piezoelectric stator. The SAW motor comprises of a cubical slider driven by Rayleigh wave generated on a piezoelectric substrate using an interdigital transducer (IDT) fabricated on the stator. In the study, a lithium niobate piezoelectric substrate is used as the stator on which aluminum IDTs are fabricated at the two edges and a cuboid slider is placed in the path of SAW propagation along with a preload. The characteristics such as displacement, velocity and forces acting on the slider for different amplitudes of wave excitations are studied. The slider in the SAW motor can move both in forward and reverse directions and the motor attains a saturated velocity with the continuous wave excitation.

セグメント構造ダイヤモンド状炭素膜を摩擦駆動面に用いた弾性表面波リニアモータ (第3報)

セグメント構造ダイヤモンド状炭素膜を摩擦駆動面に用いた弾性表面波リニアモータ (第3報)

Surface Acoustic Wave Linear Motor Using Segment-Structured Diamond-Like Carbon Films on Contact Surface (2nd Report)

Surface acoustic wave (SAW) linear motor is a kind of ultrasonic motors. The advantages of the SAW linear motor are thin structure, high force, high speed and precise positioning. On the other hand, the motor has a problem with wear of contact surface. The SAW linear motor consists of a LiNbO3 substrate as a stator transducer and a silicon substrate with distributed projections as a slider. However, the stator transducer material is easy to wear out due to friction drive. Moreover the silicon projections may enhance the wearing. Lifetime of the motor is reduced by the wear of the stator. To solve this problem, previously, segment-structured diamond-like carbon (S-DLC) films have been applied to the stator transducer surface. However, reduction of driving performance with S-DLC films stator was observed. Nonuniform shapes and heights of the segments are considered as the reason. Additionally, exfoliations of the S-DLC films were observed. The reason of this problem was that interlayer between the S-DLC films and LiNbO3 substrate was not optimized. In this report, we propose a new S-DLC transducer. This paper presents the new method, fabrication of the stator transducer and abrasion test result. Driving characteristic with the stator is also reported.

Ultra Low-Velocity Control of a Surface Acoustic Wave Linear Motor

A surface acoustic wave (SAW) linear motor is a kind of ultrasonic motor. The advantages of the SAW linear motor are thin structure, high thrust force, high velocity and precise positioning. The relationship between applied current and output velocity is, however, unstable in the low velocity range due to the friction drive principle. Therefore the SAW linear motor cannot obtain stable driving without feedback control in the low-velocity region. In this research, to realize low velocity, a pulse width modulation (PWM) control and flexible slider structure are employed. Flexible structure is installed to cancel vibration due to the PWM carrier wave. A lower velocity in the unstable range is realized. Moreover we change the calculation algorithm for the slider velocity measurement. As a result, the SAW linear motor can be driven at an ultra low velocity of 30μm/s. Additionally, driving characteristics are improved using a feedforward controller.

Surface Acoustic Wave Linear Motor Using Segment-Structured Diamond-Like Carbon Films on Contact Surface (1st Report)

Surface acoustic wave (SAW) linear motor is a kind of ultrasonic motors. The advantages of the SAW linear motor are thin structure, high force, high speed and precise positioning. On the other hand, the motor has a problem with wear of contact surface. The SAW linear motor consists of a LiNbO3 substrate as a stator transducer and a silicon substrate with distributed projections as a slider. However, the stator transducer material is easy to wear out due to friction drive. Moreover the silicon projections may enhance the wearing. Lifetime of the motor is reduced by the wear of the stator. To solve this problem, previously, segment-structured diamond-like carbon (S-DLC) films have been applied to the stator transducer surface. However, reduction of driving performance with S-DLC films stator was observed. Nonuniform shapes and heights of the segments are considered as the reason. Additionally, exfoliations of the S-DLC films were observed. The reason of this problem was that interlayer between the S-DLC films and LiNbO3 substrate was not optimized. In this report, we propose a new S-DLC transducer. This paper presents the new method, fabrication of the stator transducer and abrasion test result. Driving characteristic with the stator is also reported.

1113 2自由度制御を利用した弾性表面波リニアモータの速度制御(制御用センサ・アクチュエータ)

Surface acoustic wave (SAW) linear motor is a kind of ultrasonic motors. The advantages of the SAW linear motor are thin structure, high thrust force, high velocity and precise positioning. Relationship between applied voltage and output velocity, however, has non-linearity in a low-velocity area due to friction drive principle. Therefore the SAW linear motor cannot obtain stable driving without feedback control in the low-velocity area. Previously, to realize such low velocity, PWM control and flexible slider structure were employed. Flexible structure was installed to cancel vibration due to PWM carrier frequency. In this research, we change calculation algorithm for slider velocity measurement. As a result, SAW linear motor can be driven at a low velocity of 30mm/s. Additionally, driving characteristics is improved by using a feedforward controller.

21615 弾性表面波リニアモータの超低速駆動特性の改善(電磁力の制御,OS.1 実システムのモデリングと制御)

21615 弾性表面波リニアモータの超低速駆動特性の改善(電磁力の制御,OS.1 実システムのモデリングと制御)

Velocity Control of Surface Acoustic Wave Linear Motor Using PWM

Surface acoustic wave (SAW) linear motor is a kind of ultrasonic motors. The SAW linear motor has several advantages, such as thin structure, high thrust force, high velocity and precise positioning. Relationship between applied voltage and output velocity, however, had non-linearity in low velocity range due to friction drive principle. Therefore the SAW linear motor cannot obtain stable driving without feedback control at low velocity. To realize low velocity, PWM (pulse width modulation) control and flexible slider structure are employed. The flexible structure is installed to cancel vibration due to PWM carrier frequency. In this research, PWM is applied for controlling the slider velocity. Lower velocity in non-linear range is realized. Influence of the flexible structure upon precise positioning is investigated.

21008 弾性表面波リニアモータにおける低速度駆動の実現(実システムのモデリングと制御(2):電磁力関連,OS2 実システムのモデリングと制御)

21008 弾性表面波リニアモータにおける低速度駆動の実現(実システムのモデリングと制御(2):電磁力関連,OS2 実システムのモデリングと制御)

Optimum contact conditions for miniaturized surface acoustic wave linear motor

This paper reports the successful operation of a 70 MHz driving surface acoustic wave (SAW) linear motor with a miniaturized stator transducer. This paper also deals with an investigation into an optimized slider design for the miniaturized SAW linear motor. The performance of three silicon type sliders, with different projection size, was compared. Output forces of the three sliders were measured with change of pre-load. It was found that the slider with smaller projection tended to produce greater output force.

State-of-the-art surface acoustic wave linear motor and its future applications

Two merits of the surface acoustic wave (SAW) device are its high energy density and small size. However, the driving frequency is around 10 MHz or higher. In spite of the difficulties involved with high frequency, the high energy density is attractive for actuator applications. The SAW linear motor's no load speed and maximum output force were 1.1 m/s and 3.5 N using a silicon slider. The silicon slider dimensions were 4×4×0.3 mm 3. We made a lot of 30 μm diameter projections on the silicon surface. The acceleration was 1000 m/s 2. The SAW motor is expected to be a high speed, quick response, high resolution micro-actuator, and much more. High driving voltage was a problem. Our newly designed electrode proved that the driving voltage was reduced to less than 10 V to excite the traveling wave. For actual applications, the SAW device will be placed in a slider. This design is effective in terms of performance and cost. The nanotribology of the SAW motor is also an important and interesting subject.

Evaluation of a surface acoustic wave motor with a multi-contact-point slider

Previously, the surface acoustic wave linear motor has been demonstrated and its exact pre-load conditions investigated. Based on this previous research, multi-contact-point sliders were designed and tested. A maximum output force of 0.45 N, 450 times that obtained in preliminary experiments, was successfully obtained. Simple simulation results predicted that much larger thrust would be available by increasing the actual contact point area without changing the slider and the stator dimensions. The calculated output force was 10 N, roughly twenty times that observed experimentally. To realize the required stator texture of the contact surface, a silicon micro-machining technique or other conventional methods would be applicable.