Voice Coil Actuator Research Articles

Creating Realistic Virtual Textures from Contact Acceleration Data.

Modern haptic interfaces are adept at conveying the large-scale shape of virtual objects, but they often provide unrealistic or no feedback when it comes to the microscopic details of surface texture. Direct texture-rendering challenges the state of the art in haptics because it requires a finely detailed model of the surface's properties, real-time dynamic simulation of complex interactions, and high-bandwidth haptic output to enable the user to feel the resulting contacts. This paper presents a new, fully realized solution for creating realistic virtual textures. Our system employs a sensorized handheld tool to capture the feel of a given texture, recording three-dimensional tool acceleration, tool position, and contact force over time. We reduce the three-dimensional acceleration signals to a perceptually equivalent one-dimensional signal, and then we use linear predictive coding to distill this raw haptic information into a database of frequency-domain texture models. Finally, we render these texture models in real time on a Wacom tablet using a stylus augmented with small voice coil actuators. The resulting virtual textures provide a compelling simulation of contact with the real surfaces, which we verify through a human subject study.

Strength Analysis of Flexure Hinge Mechanism in XY Table

A new 2-DOF positioning table of high speed and accuracy, directly driven by voice coil actuator, is put forward. And a novel elastic decoupling mechanism is used in the table. As the key component of the elastic decoupling mechanism, the flexure hinge is studied, including its stiffness, maximum stress and inherence frequency. The analysis results show that the flexure hinge meets the design requirement.

Development of Microscopic Hardness and Stiffness Investigation System with MicroRobot

In order to investigate micro hardness and stiffness in a special chamber, the development of a small-force generator mechanism and a piezodriven microrobot is described in this paper. This small-force generator is simply composed of a Voice Coil Actuator (VCA) and the tandem leaf spring mechanism. The small force can be controlled by an electrical current, which is supplied to the coil and positioned precisely at the balance point with the parallel leaf spring with no mechanical friction. The full bridge strain gauges on both sides of the double leaf spring can detect a small force that is applied to the sample with a microindenter. This handmade small device can produce and verify small forces up to 17 mN with good linearity and a 50 µN resolution. The displacement of the indenter head can be also measured by the Linear Valuable Differential Transformer (LVDT) on the machine for monitoring the depth behavior of the indenter during the whole dwell time. The small force generator with the indenter can be implemented on the piezodriven microrobot to check the microscopic hardness and stiffness. This microrobot can move around the measurement area precisely step by step with 1 µm steps on a metal plate, so that the sample can be scanned with microscopic resolution in situ, such as in an SEM chamber. In the experiment results, the basic performance of microelasticity investigations with a certified hardness block was successfully checked and the indentation load-depth characteristics were precisely acquired on the path of the microrobot.

Concept, modeling, and performance prediction of a low-cost, large deformable mirror

While it is attractive to integrate a deformable mirror (DM) for adaptive optics (AO) into the telescope itself rather than using relay optics within an instrument, the resulting large DM can be expensive, particularly for extremely large telescopes. A low-cost approach for building a large DM is to use voice-coil actuators connected to the back of the DM through suction cups. Use of such inexpensive voice-coil actuators leads to a poorly damped system with many structural modes within the desired bandwidth. Control of the mirror dynamics using electro-mechanical sensors is thus required for integration within an AO system. We introduce a distributed control approach, and we show that the "inner" back sensor control loop does not need to function at low frequencies, leading to significant cost reduction for the sensors. Incorporating realistic models of low-cost actuators and sensors together with an atmospheric seeing model, we demonstrate that the low-cost mirror strategy is feasible within a closed-loop AO system.

Process control for ultrasonic hole-drilling in hard brittle materials

Ultrasonic drilling offers a solution to bore sub-millimetre holes of high diameter-to depth ratio in difficult to machine brittle materials. A key aspect of the process is to maintain a proper gap between tool and work piece. This paper presents the successful solution developed to address this issue. In our approach, we vibrate the work piece and control the motion of the tool, which is constrained by an aerostatic bearing and generated by a voice coil actuator. We use the voice coil to measure the force acting between tool and work piece. We measure the tool displacement with an Eddy current sensor. Using the two sensor measurements, we developed a control algorithm in which the tool is displaced in such a way as to maintain the tool-work piece interaction force constant. The paper presents experimental details of the characterization of the control loop and results of drilling experiments.

Development of Wearable Micro-actuator Array for 3-D Virtual Tactile Displays

A novel 4 by 4 array of electromagnetic micro-actuators operating on the principle of voice-coil actuators is presented. The intended application of the array is dynamic tactile stimulation, where multiple actuators generate an illusion of touching a moving pattern. In comparison to earlier designs [1-3], the device has smaller dimensions of 2.28 mm in diameter and 7 mm in length, which allowed its use in an array capable of hosting up to a 5 by 5 set of actuators with a rectangular shape covering an area of 18 mm by 21 mm. Using finite element analysis of several conceptual designs of actuators [1,4,5], it was established that the voice-coil type device (where the coil is the moving part) has most beneficial characteristics for the envisioned application. These include sufficient force over a relatively large distance, allowing tactile stimulation of surfaces with irregular shape, fast response, and small foot-print that matches the density of the tactile sensory neurons in the human finger. Eexperimental evaluation of the operation of neighboring actuators spaced at 3.3 mm apart, indicates that there is no crosstalk between the actuators. The resulting density exceeds that of previously reported alternative designs based on moveable permanent magnets [4,6]. Static force measurement indicate that each micro-actuator can produce at least 26 mN of repulsive force over a stroke of 2100 μm with a peak force of 34 mN. The driving circuit operates at 13.5V and generates a vibration frequency of up to 265 Hz without significant change of the force-displacement characteristics. In the higher frequency range (above 100 Hz) the actuator provides at least 15 mN of force over a slightly reduced stroke of 2300 μm, and a peak force of 21 mN. All of the above parameters meet the required threshold values of tactile human perception known from [2] and [3].

Tip-tilt mirror suspension: Beam steering for advanced laser interferometer gravitational wave observatory sensing and control signals

We describe the design of a small optic suspension system, referred to as the tip-tilt mirror suspension, used to isolate selected small optics for the interferometer sensing and control beams in the advanced LIGO gravitational wave detectors. The suspended optics are isolated in all 6 degrees of freedom, with eigenmode frequencies between 1.3 Hz and 10 Hz. The suspended optic has voice-coil actuators which provide an angular range of ±4 mrad in the pitch and yaw degrees of freedom.

Large angle and high linearity two-dimensional laser scanner based on voice coil actuators

A large angle and high linearity two-dimensional laser scanner with an in-house ingenious deflection angle detecting system is developed based on voice coil actuators direct driving mechanism. The specially designed voice coil actuators make the steering mirror moving at a sufficiently large angle. Frequency sweep method based on virtual instruments is employed to achieve the natural frequency of the laser scanner. The response shows that the performance of the laser scanner is limited by the mechanical resonances. The closed-loop controller based on mathematical model is used to reduce the oscillation of the laser scanner at resonance frequency. To design a qualified controller, the model of the laser scanner is set up. The transfer function of the model is identified with MATLAB according to the tested data. After introducing of the controller, the nonlinearity decreases from 13.75% to 2.67% at 50 Hz. The laser scanner also has other advantages such as large deflection mirror, small mechanical structure, and high scanning speed.

3-D Analytical Calculation of the Torque Between Perpendicular Magnetized Magnets in Magnetic Suspensions

This paper presents novel equations that enable the direct analytical calculation of the interaction torque between perpendicularly magnetized cuboidal permanent magnets in free space. These expressions complement the expressions for the interaction force and stiffness that are already available in literature and are computationally inexpensive due to their analytical nature. They are suitable in the design and analysis of ironless structures such as certain types of magnetic bearings or for obtaining the peeling torque on the magnets in devices such as voice coil actuators or electron beam focusing devices.

손 떨림 방지를 위한 OIS 액추에이터의 설계

Recently mobile phone camera become generally spread, it is required to develop high resolution, multi-functional camera module for obtaining high image quality. To satisfy this demand, number of pixels has been increased and pixel size decreased in small mobile phone cameras. As a result, image quality is seriously dropped by blur phenomena. Especially when hand tremble is occurred, image quality is dropped by camera shake. Therefore, to obtain high quality image, it is necessary to compensate user`s hand tremble. In this paper, we propose voice coil actuator for compensating hand tremble, which can apply optical image stabilization (OIS) system. Sensitivity analysis and size optimization are performed to obtain high driving force. Finally, it is confirmed that the optimized electromagnetic circuit can be applied in OIS system.

Design of a Direct-Drive XY Table System: Electromechanical and Dynamic Optimization

This paper presents the electromechanical system modeling of a direct-drive precision positioning XY table used for wire bonding. The XY table is directly driven by voice coil actuator (VCA) and therefore the equivalent circuit of VCA was built to construct the co-simulation platform of electromechanical system. By use of finite element analysis (FEA) and co-simulation method based on ADAMS and MATLAB/SIMULINK software, the spring as the key component in the decoupling mechanism was optimized and the matching law of stiffness and preload was given. The mechanical model of decoupling mechanism was then built up and the matching law was validated by theoretical analysis. The damp-spring-mass system of y-axis table further illustrated the matching law. For the complex electromechanical coupling system, the method of co-simulation could reflect the actual properties of system better compared with the oversimplified analytical model. The achieved results would be helpful to the dynamic design of the kind of manufacturing equipment and provide theoretical guidance for the control system development and testing.

Digital Control of PID for Voice Coil Actuator and System Simulation

This paper introduced the principle and method of designing for Voice Coil Actuator based on the characteristic of Voice Coil Actuator. The Digital Control Of PID For Voice Coil Actuator are presented to servo the system of one dimension, System simulation results were given out.

Characterization of a traceable profiler instrument for areal roughness measurement

A two-dimensional profiler instrument was designed and realized at the PTB (Physikalisch-Technische Bundesanstalt). The main function of the instrument is to provide traceable results in the field of roughness measurement. It is equipped with a linear moving stylus which is guided by precision air bearings. The moving part of the stylus has weight around 1 g and is carried by a magnetic field. The contacting force of the tip onto the surface under test is controlled by a small voice coil actuator in a closed control loop. Vertical movements of the stylus are captured by two different, completely independent measurement systems, covering a range of 100 µm. The first one is an interferometer, which provides a traceable signal, and the second one is an inductive measurement system. The signal from the inductive measurement system is calibrated by the interferometer. The sample under test is carried within the x–y-plane by a linear guided table with low noise air bearings. These air bearings are preloaded by vacuum and a constant gap is achieved by gas pressure controllers. Both axes of the table are driven by linear voice coil actuators and their movement in the plane is measured by linear encoders. The sample carrier is equipped with two axes tilt compensation, by which the sample under test can be levelled automatically using the measurement system of the stylus. Real-time data acquisition, manual handling and automated procedures are managed by a programmable controller and proprietary software written in LabVIEW. After measurement, data from the system can be directly transferred into the smd- or sdf-format. Results of measurements on different samples to characterize the metrological behaviour of the instrument will be reported. To characterize the uncertainty of the instrument, a model is applied, which is in accordance with approved rules for contact stylus instruments.

A Hand-held Instrument to Maintain Steady Tissue Contact during Probe-Based Confocal Laser Endomicroscopy

Probe-based confocal laser endomicroscopy (pCLE) provides high-resolution in vivo imaging for intraoperative tissue characterization. Maintaining a desired contact force between target tissue and the pCLE probe is important for image consistency, allowing large area surveillance to be performed. A hand-held instrument that can provide a predetermined contact force to obtain consistent images has been developed. The main components of the instrument include a linear voice coil actuator, a donut load-cell, and a pCLE probe. In this paper, detailed mechanical design of the instrument is presented and system level modeling of closed-loop force control of the actuator is provided. The performance of the instrument has been evaluated in bench tests as well as in hand-held experiments. Results demonstrate that the instrument ensures a consistent predetermined contact force between pCLE probe tip and tissue. Furthermore, it compensates for both simulated physiological movement of the tissue and involuntary movements of the operator's hand. Using pCLE video feature tracking of large colonic crypts within the mucosal surface, the steadiness of the tissue images obtained using the instrument force control is demonstrated by confirming minimal crypt translation.

Experimental Investigations of the Power Absorbed at Mechanical Resonance

This article describes the results of an investigation concerning the power absorbed at mechanical resonance for a single degree of freedom vibration system. Regarding the experimental purposes, the article proposes a cantilever beam set-up actuated by a voice-coil actuator and a computer-aided power monitoring technique. The absorbed power is evaluated in a steady-state regime for different values of excitation frequency around the resonance (the first mode of vibration). The experimental results are afterwards compared to the theoretical predictions. In addition, some transient regimes generated by beat vibrations are explored. The negative absorbed power has been observed. The article proposes an active vibration damping technique, based on actuation with a negative modal power supply.

Smart Double Panel for the Sound Radiation Control: Blended Velocity Feedback

In this paper an active damping method using blended velocity feedback for the reduction of sound transmission through a simplified aircraft double panel is considered. The double panel consists of a source and a radiating panel, which are coupled acoustically by the air in the cavity between them and structurally by four elastic mounts. The double panel is equipped with an array of nine voice-coil actuators that can react against the two panels. A velocity sensor is mounted at both panel junctions of each actuator. The outputs from the sensors on the source and radiating panels are weighted by factors α and 1 - α, respectively. The two weighted signals are then subtracted and combined into the error signal fed back to the actuator via a constant amplification gain. The stability and performance of such a decentralized velocity feedback system are analyzed experimentally as a function of the weighting factor α. Reductions between -10 and -18 dB in the radiated sound power have been measured at low-frequency resonances of the double panel, depending on the weighting factor implemented.

고속 엘리베이터 능동진동제어 실험

This paper is concerned with the active control experiments on elevator vibrations by means of the active roller guide. To this end, a roller guide was designed using a voice-coil actuator and linear guide. A simple proportional control algorithm combined with the band-pass filter was implemented using the DSP. Based on the initial experiments, a new control system which can handle lateral and front-back vibrations of elevator was built and tested using the elevator test tower. The experimental results show that the elevator vibrations are reduced by the active control technique.

High-powered voice coil actuator for fast steering mirror

Voice coil actuators (VCAs) are applied in a fast steering mirror (FSM), precision positioning platform, etc. These applications demand that the VCAs used are simple, inexpensive, reliable, and efficient. In this paper, we report a novel VCA with concentration flux-line structure. The VCA greatly reduces the magnet leakage and has less electromagnetic interference with other electronic devices. The output force sensitivity of the VCA is 4.17 N/A with a coil of 300 turns and the stroke is ±2.5 mm. Driven by this VCA, the mechanical scanning angle of the FSM can achieve ±4.9 deg when the scanning frequency is 100 Hz.

Control System Research of 2-DOF Precision Positioning Table for IC Packaging

In order to improve the precision and efficiency of IC packaging for wafer wire bonding equipment, a new 2-DOF positioning table of high speed and accuracy, directly driven by voice coil actuator, is put forward. By establishing dynamic model of VCA and positioning table, the electromechanical coupling control system based on minimum deadbeat response controlling algorithm is proposed. The prototype experiment shows that the new 2-DOF positioning table is robust and of good dynamic performance.

音圈电机驱动的球面副支撑式快速控制反射镜设计

音圈电机驱动的球面副支撑式快速控制反射镜设计