Helmholtz resonance in a piezoelectric–hydraulic pump-based hybrid actuator

This paper demonstrates that a hydraulically acting Helmholtz resonator can exist in a piezoelectric–hydraulic pump (PHP) based hybrid actuator, which in turn affects the volumetric efficiency of the PHP. The simulation and experimental results illustrate the effect of Helmholtz resonance on the flow rate performance of the PHP. The study also shows how to shift the Helmholtz resonant frequency to a higher value through changing parameters such as the cylinder diameter and the effective bulk modulus of the working fluid, which will improve the volumetric efficiency and broaden the operating frequency range of the PHP actuator.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90809/1/0964-1726_20_1_015010.pd

A Three – tier bio-implantable sensor monitoring and communications platform

One major hindrance to the advent of novel bio-implantable sensor technologies is the need for a reliable power source and data communications platform capable of continuously, remotely, and wirelessly monitoring deeply implantable biomedical devices. This research proposes the feasibility and potential of combining well established, ‘human-friendly' inductive and ultrasonic technologies to produce a proof-of-concept, generic, multi-tier power transfer and data communication platform suitable for low-power, periodically-activated implantable analogue bio-sensors. In the inductive sub-system presented, 5 W of power is transferred across a 10 mm gap between a single pair of 39 mm (primary) and 33 mm (secondary) circular printed spiral coils (PSCs). These are printed using an 8000 dpi resolution photoplotter and fabricated on PCB by wet-etching, to the maximum permissible density. Our ultrasonic sub-system, consisting of a single pair of Pz21 (transmitter) and Pz26 (receiver) piezoelectric PZT ceramic discs driven by low-frequency, radial/planar excitation (-31 mode), without acoustic matching layers, is also reported here for the first time. The discs are characterised by propagation tank test and directly driven by the inductively coupled power to deliver 29 μW to a receiver (implant) employing a low voltage start-up IC positioned 70 mm deep within a homogeneous liquid phantom. No batteries are used. The deep implant is thus intermittently powered every 800 ms to charge a capacitor which enables its microcontroller, operating with a 500 kHz clock, to transmit a single nibble (4 bits) of digitized sensed data over a period of ~18 ms from deep within the phantom, to the outside world. A power transfer efficiency of 83% using our prototype CMOS logic-gate IC driver is reported for the inductively coupled part of the system. Overall prototype system power consumption is 2.3 W with a total power transfer efficiency of 1% achieved across the tiers

Laser space rendezvous and docking system study continuation

Investigations were made of a configuration for a spaceborne laser radar (ladar) to meet the requirements for rendezvous and docking with a cooperative object in synchronous orbit. An analysis was completed of laser phase locking techniques, while experimental verification was made of pulse repetition frequency and resonant scanning control loops. Data measurements on a satellite mock-up were also made. The investigation supports the original contention that a rendezvous and docking ladar can be configured to offer a cost effective and reliable solution to envisioned space missions

A smart 3D ultrasonic actuator for unmanned vehicle guidance industrial applications

A smart piezoelectric ultrasonic actuator with multidegree of freedom for unmanned vehicle guidance industrial applications is presented in this paper. The proposed actuator is aiming to increase the visual spotlight angle of digital visual data capture transducer. Furthermore research are still undertaken to integrate the actuator with an infrared sensor, visual data capture digital transducers and obtain the trajectory of motion control algorithm. The actuator consists of three main parts, the stator, rotor and housing unit. The stator is a piezoelectric ring made from S42 piezoelectric material, bonded to three electrodes made from a material that has a close Characteristics to the S42. The rotor is a ball made from steel material. The actuator working principles is based on creating micro elliptical motions of surface points, generated by superposition of longitudinal and bending vibration modes, of oscillating structures. Transferring this motion from flexible ring transducer through the three electrodes, to the attached rotor, create 3D motions. The actuator Design, structures, working principles and finite element analysis are discussed in this paper. A prototype of the actuator was fabricated and its characteristics measured. Experimental tests showed the ability of the developed prototype to provide multidegree of freedom with typical speed of movement equal to 35 rpm, a resolution of less than 5μm and maximum load of 3.5 Newton. These characteristics illustrated the potential of the developed smart actuator, to gear the spotlight angle of digital visual data capture transducers and possible improvement that such microactuator technology could bring to the unmanned vehicle guidance and machine vision industrial applications

A smart ultrasonic actuator with multidegree of freedom for autonomous vehicle guidance industrial applications

A piezoelectric ultrasonic actuator with multidegree of freedom for autonomous vehicle guidance industrial applications is presented in this paper. The actuator is aiming to increase the visual spotlight angle of digital visual data capture transducer. It consists of three main parts, the stator, rotor and housing unit. The stator is a piezoelectric ring made from S42 piezoelectric ceramics material, bonded to three electrodes made from a material that has a close Characteristics to the S42. The rotor is a ball made from stainless steel materials. The actuator working principles is based on creating micro elliptical motions of surface points, generated by superposition of longitudinal and bending vibration modes, of oscillating structures. Transferring this motion from flexible ring transducer through the three electrodes, to the attached rotor, create 3D motions. The actuator Design, structures, working principles and finite element analysis are discussed in this paper. A prototype of the actuator was fabricated and its characteristics measured. Experimental tests showed the ability of the developed prototype to provide multidegree of freedom with typical speed of movement equal to 35 rpm, a resolution of less than 5μm and maximum load of 3.5 Newton. These characteristics illustrated the potential of the developed smart actuator, to gear the spotlight angle of digital visual data capture transducers and possible improvement that such micro-actuator technology could bring to the autonomous vehicle guidance and machine vision industrial applications. Furthermore research are still undertaken to develop a universal control prototype, integrate the actuator with an infrared sensor, visual data capture digital transducers and obtain the trajectory of motion control algorithm

Switching sliding mode force tracking control of piezoelectric-hydraulic pump-based friction element actuation systems for automotive transmissions

In this study, a nonlinear sliding-mode controller is designed for force tracking of a piezoelectric-hydraulic pump (PHP)-based actuation system, which is developed to replace the current electro-hydraulic actuation systems for automatic transmission (AT) friction elements, such as band brakes or clutches. By utilizing the PHP, one can eliminate the various hydraulic components (oil pump, regulating valve and control valve) in current ATs and achieve a simpler configuration with more efficient operation. With the derived governing equation of motion of the PHP-based actuation system integrated with the friction element (band brake), a switching control law is synthesized based on the sliding-mode theory. To evaluate the effectiveness of the proposed control law, its force tracking performance for the engagement of a friction element during an AT ##IMG## [http://ej.iop.org/images/0964-1726/18/8/085004/sms306895ieqn1.gif] {1 to 2} up-shift is examined experimentally. It is shown that one can successfully track the desired force trajectory for AT shift control with small tracking error. This study demonstrates the potential of the PHP as a new controllable actuation system for AT friction elements.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65109/2/sms9_8_085004.pd

Theoretical and experimental investigation of IV-VI mid-infrared multiple quantum wells vertical cavity surface emitting lasers.

Lateral mode suppression techniques other than reduction of pump spot size need to be developed. Air-post pillar structure and electrically pumped configuration certainly need to be investigated.Throughout this research, several simulation programs have been developed. These software packages can utilize further developments of mid-infrared lasers. Also, a working prototype of optically pumped ECT-VCSEL was built, as described in chapter 6. However, the heat dissipation issue is still the prime obstacle for room temperature CW operation.Based on our findings, further fabrication development is necessary to improve the laser performance. Other alternative approaches such as edge emitting source with the same ECT configuration also need to be explored.Epi-down (wherever applicable) is a key design factor for any mid-infrared laser regardless of the design. Due to the direct contact of the active region to the heat-sink, this configuration provides the highest possible heat dissipation.The multilateral modes and poor heat dissipation are the main obstacles of room temperature operation. These issues were addressed by using an external cavity configuration and by the reduction of the pump spot size to 90mum. Nevertheless, these challenges present opportunities for the ongoing research

Model and Design of a Power Driver for Piezoelectric Stack Actuators

A power driver has been developed to control piezoelectric stack actuators used in automotive application. A FEM model of the actuator has been implemented starting from experimental characterization of the stack and mechanical and piezoelectric parameters. Experimental results are reported to show a correct piezoelectric actuator driving method and the possibility to obtain a sensor-less positioning contro