This paper presents the non-collocated active damping system (NCADS) applied to a ram-type milling machine for achieving high-throughput machining of both rough-and finishing-milling. When installing an active damping system to practical ram-type milling machines, the available locations are limited due to the space constraints and the interference against machining processes. Therefore, it is often the case that the non-collocated configuration of the active damper becomes inevitable. Such non-collocated active damping system (NCADS) may require high force-density actuators to compensate the poor controllability, and right half-plane zeros caused by the NCADS make it challenging to maximize the active damping performance while securing the controller stability. In addition, the different vibration characteristics during the rough-and finishing-milling require the vibration control strategies adapted to the machining operations. We propose the sensitivity function shaping methods in NCADS for high-throughput operation of both rough-and finishing-milling. Using the proposed method, we increase the dominant-mode dynamic stiffness of the ram structure by 154% for rough-machining operations, and thereby increase the chatter-free cutting depth up to 3.5 mm. Also, in the high-speed finish-milling test, we reduce the retainer vibration by 58% and thereby suppress the associated beating mark on the surface profile, achieving the surface roughness reduction by 40%. The results validates the high-throughput machining performance of the proposed vibration suppression control methods in both rough-and finishing-milling.

Control moment gyroscope (CMG), used for attitude control of spacecraft or satellites, requires thermal analysis to manage and optimize power consumption as it generally operates incessantly for the lifespan in extreme conditions of space. In this study, to more accurately calculate the stabilized temperature of the system, heat generation was applied as a boundary condition in a steady-state thermal analysis, represented as a function of the system and component temperatures. A simplified finite element method (FEM) model using a steady -state -based thermal resistance method were adopted to analyze the factors affecting the thermal stability of the system under extreme conditions at20 degrees C and 70 degrees C. At -20 degrees C, under the condition of a total heat dissipation of 28.22 W, the system exhibited a high maximum temperature rise of 43 degrees C on the motor PCB. At 70 degrees C, with a total heat dissipation of 7.2 W, the maximum temperature rise of the system was relatively low at 5.9 degrees C, occurring at the bearing. The results indicated that the temperature of the bearing component strongly influenced the heat dissipation in the system. The friction torque of the bearing, which is the most significant factor regarding heat dissipation and power consumption, was noted to be approximately 10 times higher at -20 degrees C than at 70 degrees C. Consequently, the heat dissipation from the bearing was approximately 4 times higher, whereas the heat dissipation from the motor was approximately 10 times higher at -20 degrees C than at 70 degrees C.

Binary actuators with discrete states are widely used in various fields, including medical endoscopes, combustion engine valves, and manufacturing applications with the advantages of simple system structure, low manufacturing cost, and high repeatability. Electromagnetic actuating mechanism is often adopted for such binary actuators due to its simplicity and accessibility. By utilizing the magnetic flux of permanent magnet (PM) and electromagnet simultaneously, such electromagnetic actuators can achieve higher force density with minimum power consumption. However, nonlinear magnetic reluctance force accelerates the mover toward the discrete state, causing an impulsive collision with the stator and so impairing the reliability of the binary actuator performance. To address such issues, this article proposes a PM-driven-flux-based sensorless control of electromagnetic binary actuators to realize the soft landing of the mover and therefore minimize the undesired contact bounce, surface wear, and associated acoustic noise. Overcoming the trade-off between the soft landing performance, fast actuation time, and potential energy consumption is also considered in the proposed control strategy. The experimental results show significant reduction rates more than 80% on the contact bounce amplitude and mover landing velocity, while also reducing the actuation time and energy consumption more than 30% as compared to the other conventional control methods in prior art.

In this paper, we present identification methods of normal-direction motor parameters and a force ripple reduction method in the normal direction for permanent-magnet linear synchronous motors (PMLSMs). This paper discusses the force generation mechanism of a PMLSM both in the normal and tangential directions by the D- and Q-axis currents, which is utilized for identifying and suppressing the motor force ripple in the normal direction. Using the proposed identification method on the experimental setup of a linear stage driven by an iron-cored PMLSM, we identify the normal-direction force constant with an error of only 7% as compared to a direct measured data from a dynamometer. The geometry-driven ripple in the normal direction is also identified by experimentally estimating the dominant 2nd-and 6th-order spatial harmonics, which also show significant fidelity with an NRMSE (peak-to-peak normalized root-mean-square error) of only 3.39% as compared to the dynamometer measurement. Using the identified motor parameters, we achieve the force ripple reduction in the normal direction by 84.6% and 87.8% in peak-to-peak and root-mean square (RMS) values, respectively.

In phase-shifting profilometry (PSP), any motion during the acquisition of fringe patterns can introduce errors because it assumes both the object and measurement system are stationary. Therefore, we propose a method to pixel-wise reduce the errors when the measurement system is in motion due to a motorized linear stage. The proposed method introduces motion-induced error reduction algorithm, which leverages the motor's encoder and pinhole model of the camera and projector. 3D shape measurement is possible with only three fringe patterns by applying geometric constraints of the digital fringe projection system. We address the mismatch problem due to the motion-induced camera pixel disparities and reduce phase-shift errors. These processes are easy to implement and require low computational cost. Experimental results demonstrate that the presented method effectively reduces the errors even in non-uniform motion.

This paper presents the studies on the force generation-mechanism of iron-cored permanent-magnet linear synchronous motors (PMLSMs) by introducing the field-decomposition method in the D-Q axes. Using the proposed field-decomposition method (FDM), the force generation-mechanism can be analytically described for i) the geometry-driven and current-driven motor forces, ii) the generated DC motor forces in normal and tangential directions, iii) the harmonics of AC force ripples caused by end- and slotting-effect, together with the perpendicularly-coupled forces by D-Q currents, and iv) the force equations for all the decomposed motor forces. This paper also presents the experimental validation of the FDM and the associated PMLSM force generation-mechanism by directly measuring various types of forces. The significant agreement is confirmed between the experimental results and the prediction by the proposed method on the current and force relationship, the DC and AC force generation, and the force ripple harmonics.

During the periodic drug administration for chronic diseases, unexpected battery depletion can be significantly problematic for the patients. While body heat harvesting utilizing the wearable thermoelectric generator (WTEG) shows the significant potential in continuous drug delivery systems (DDSs) by providing ceaseless power source, the power and the voltage output might not be sufficient to drive micropump actuators in such drug delivery systems. The continuous actuating current also imposes an additional challenge in developing efficient and compact voltage boosting circuits. In this paper, we propose an ultra-low-energy operating method of the WTEG-powered electromagnetic micropump system. In combination with our electromagnetic bi-stable actuator (EBA) where the energy demand is discretized, we present (1) the dedicated high-efficient charge pumps (CPs) (2) and the actuating pulse control method to prevent redundant energy waste. The proposed 10-stage charge pump is designed to reduce the conversion loss by utilizing multiple flying-capacitor switching structure, and the 2-stage series-parallel charge pump (SPCP) is fabricated with flexible thin-film super-capacitors (TFSCs) to realize the high boosting performance within compact and wearable features. Applying the proposed control method with the 10-stage CP in our WTEG-powered micropump system, we significantly reduce the charging time per actuation by 88.8% compared to the commercial boosting circuit. Also, the 2-stage SPCP achieves 84.0% reduction in the charging time while utilizing flexible and wearable features, showing a significant potential for self-powered wearable healthcare applications.

In phase-shifting profilometry (PSP), errors can be introduced by any motion during the acquisition of fringe patterns, as it assumes both the object and the measurement system are stationary. To address this issue, we propose a pixel-wise motion-induced error reduction method when the measurement system is in motion due to a motorized system. Our proposed method introduces a novel motion-attentive phase-shifting algorithm and leverages the motor’s encoder and the pinhole model of the camera and projector. It enables accurate 3D shape measurement with only three fringe patterns, leveraging the geometric constraints of the digital fringe projection system. We address the mismatch problem due to motion-induced camera pixel disparities and reduce phase-shift errors. These processes are easy to implement and require low computational cost. Experimental results demonstrate that the presented method effectively reduces errors even in non-uniform 3D motion.

Crosstalk of microbes with human gut epithelia and immune cells is crucial for gut health. However, there is no existing system for a long-term co-culture of human innate immune cells with epithelium and oxygen-intolerant commensal microbes, hindering the understanding of microbe-immune interactions in a controlled manner. Here, we established a gut epithelium-microbe-immune (GuMI) microphysiological system to maintain the long-term continuous co-culture of Faecalibacterium prausnitzii/Faecalibacterium duncaniae with colonic epithelium, antigen-presenting cells (APCs, herein dendritic cells and macrophages), and CD4+ naive T cells circulating underneath the colonic epithelium. In GuMI-APC condition, multiplex cytokine assays suggested that APCs contribute to the elevated level of cytokines and chemokines secreted into both apical and basolateral compartments compared to GuMI condition that lacks APC. In GuMI-APC with F. prausnitzii (GuMI-APC-FP), F. prausnitzii increased the transcription of pro-inflammatory genes such as toll-like receptor 1 (TLR1) and interferon alpha 1 (IFNA1) in the colonic epithelium, without a significant effect on cytokine secretion, compared to the GuMI-APC without bacteria (GuMI-APC-NB). In contrast, in the presence of CD4+ naive T cells (GuMI-APCT-FP), TLR1, IFNA1, and IDO1 transcription levels decreased with a simultaneous increase in F. prausnitzii-induced secretion of pro-inflammatory cytokines (e.g., IL8) compared to GuMI-APC-FP that lacks T cells. These results highlight the contribution of individual innate immune cells in regulating the immune response triggered by the gut commensal F. prausnitzii. The integration of defined populations of immune cells in the gut microphysiological system demonstrated the usefulness of GuMI physiomimetic platform to study microbe-epithelial-immune interactions in healthy and disease conditions.

This article presents a 2-degree-of-freedom (DOF) near-zero power control (NZPC) method to significantly reduce the power consumption of a single-body permanent magnet (PM)-biased 2-DOF magnetic levitation actuator for high-throughput noncontact transportation operations. While most of the power reduction methods for the magnetic levitators focus on the compensation of static disturbances such as the target mass uncertainty, control strategies regarding the dynamic disturbance such as the inertial force during the noncontact transportation have been less explored, even though the associated power consumption can be significant for the repetitive transportation tasks. The proposed 2-DOF NZPC method uses 1) the position-controlled loops as the backbone structure, 2) the current-integrating feedback loops to compensate the static disturbances in both DOFs, and 3) the adaptive referencing scheme to compensate the dynamic disturbance. The adaptive referencing method estimates the dynamic equilibrium locus even with an unknown target mass, achieving near-zero power for the noncontact transportation. Using the single-body 2-DOF levitator prototype, we experimentally validate the power reduction performance during high-acceleration noncontact transportation tests with different unknown target mass values. As compared to the case where the identical PM-biased levitator is operated without any compensation method, the proposed 2-DOF NZPC method achieves a maximum of 95% reduction in the accumulated power consumption. The results show a significant potential for industrial applications where high-throughput transportation tasks are required in a noncontact manner.

Understanding the intrinsic thermal transport behavior of living blood-perfused tissue is essential in applications that require predicting the correct thermoregulation behavior of humans, discovering the location of abnormal tissues, and treating cancer through hyperthermia or thermal ablation. In this study, we employ an in vivo measurement technique that genuinely measures the intrinsic tissue thermal conductivity and blood perfusion rate as a function of tissue temperature. The emphasis is on "in vivo" measurement because physiological differences across individuals must be considered (e.g., water content within the tissue). Tissue temperatures from 30.5 degrees C to 35.5 degrees C yielded average intrinsic thermal conductivity values of 0.33 +/- 0.04 W/m-K in three subjects. This value agrees well with that of excised human epidermis (0.21-0.41 W/m-K). The blood perfusion rate inevitably increased from 1.43 x 10-4 to 3.42 x 10-3 m3/s/m3 with increasing tissue temperature consequently from vasomotion. The findings suggest that the proposed approach can serve as a noninvasive, real-time, personalized, and in vivo method for determining the intrinsic thermal behavior of living blood-perfused tissue. Such a methodology also has the potential to revolutionize fields that deal with tumor modeling, treatment, and thermal comfort optimization, ultimately benefiting human health and well-being.

This paper presents the dual-leakage hybrid layer modeling (DL-HLM) method for the linear permanent-magnet synchronous motors (LPMSMs) in a heavily saturated state. The proposed hybrid model consists of the nonlinear dual-leakage flux-tube model for the iron-cored armature where the geometric saliency exists, the Maxwell model for the PM track with uniform layers, and the hybrid input-output conversion method for the iteration between two models. As the minimum number of leakage flux paths, the dual-leakage flux-tube network is selected, considering the opposite-direction leakage fluxes generated by the flux-steering effect in heavily saturated iron-core teeth. The novel reluctance adaptation methods are also proposed, which allow the DL-HLM to accurately capture significant nonlinearities even with the minimum number of leakage flux paths, thereby correctly estimating motor forces in high-performance LPMSMs. The proposed DL-HLM is validated comparing to the equivalent finite element method (FEM) in terms of the magnetic fields in the working air-gap and motor force performances. The proposed modeling method estimates the magnetic fields and forces with an accuracy of higher than 95% even at significantly high saturation levels while simultaneously achieving multiple-orders-of-magnitude faster computation time as compared to the FEM.

This article presents the 3-D integrated sub-domain model (3-D ISM) for the 6-degree-of-freedom (DOF) screw-motion permanent-magnet synchronous motors (Sm-PMSMs). For the actively controlled and decoupled 6-DOF motion, the novel pattern of PM-array is introduced, consisting of the checker-board PMs to drive the 2-DOF screw motion and the additional tilting PMs for the other 4-DOF magnetic bearings. The armature of the proposed Sm-PMSM design contains both the linear coil sets and the rotational coil sets, where the D-Q current excitation scheme with the peak current modulation method is utilized to generate the 6-DOF forces and torques in a decoupled manner. The 3-D ISM presented in this article accurately estimates the magnetic fields in the 3-D cylindrical space with an on-load condition, integrating the PM-induced fields from the magnetic scalar potential model and the current-induced fields from the hybrid vector potential model. The proposed 3-D ISM is validated by the equivalent 3-D finite element analysis (FEA) model, comparing the on-load magnetic fields, and the decoupled 6-DOF forces and torques. The fidelity of the proposed model is observed with an accuracy greater than 96%, while simultaneously improving the computational speed by two orders-of-magnitude as compared to the 3-D FEA.

This paper presents the design and control of a three degrees-of-freedom (3-DOF) magnetic levitation module for fine-positioning short-stroke actuators to be serially connected to high-acceleration long-stroke stages. The 3-DOF levitator module consists of two stator assemblies with iron-cores having actuating coils and permanent magnets (PMs) along the magnetic path. The levitating target is an U-shaped rotor with its weight passively compensated by the PM-biased flux and the lateral-direction force is balanced out by the symmetric structure. In such a magnetic levitator design, the PM-biased flux is superposed with the current-driven flux, enabling to control the reluctance forces in both the levitational and lateral directions in a decoupled manner to achieve active 3-DOF motion control. The control performance of the proposed 3-DOF magnetic levitator is experimentally validated to have RMS (root-mean-square) position tracking errors of 4.3 µm for the translation motions and 5.97 µdeg for the rotational motion. These control performances show a great potential of the magnetic levitation module to be utilized for fine-positioning short-stroke actuators that can overcome high inertial forces generated by serially-connected long-stroke actuators such as high-throughput linear stages and robotic arms.

Continuous monitoring of vital signs and timely treatment are the future trends for wearable and implantable healthcare systems, which inevitably require ceaseless power supply. Discharged batteries could be detrimental to the health of people, such as those with type 1 diabetes, whose glucose levels should be monitored and controlled through timely insulin injections. Here, we demonstrate a feasible true continuous healthcare system for type 1 diabetes by combining a low-energy micropump, self-powered glucose sensor, and ceaseless power supply. By converting body heat into electricity to charge a battery for 790.1 s, we acquired 136.8 mJ (100%) of energy, which was used to operate the micropump and sensor for 74.6 mJ (54.5%) and 25.3 mJ (18.5%), respectively; the surplus 36.9 mJ (27.0%) was stored in the battery. These findings can help realize a true continuous healthcare system in the future.

While electromagnetic micropumps have potential for the low operating voltage within a compact configuration, the significant power consumption level due to the continuous current input during pumping operations could hinder the application to battery-driven systems such as wearable drug delivery devices. This paper presents an energy-efficient and self-locking micropump system using a single bi-stable electromagnetic actuator with a double-sided tubing. The proposed bi-stable electromagnetic actuator consists of a single-body iron mover and a PM-attached stator, the combination of which can minimize the reluctance of the magnetic flux path induced by a current excitation, thereby achieving the high energy-efficiency. The actuator is integrated into the micropump system with a double-sided tubing configuration, which provides (i) the assistant force during switching motions in order to reduce the energy consumption, (ii) the self-primed pumping operation with a sequence of the pumping phase and the loading phase, and (iii) the self-locking characteristic to prevent unwanted flows during non-operating states. The low-voltage and low-energy characteristics of the proposed micropump system are experimentally validated. The switching voltage and the switching energy are measured to be a minimum of 0.43 V and 1.88 mJ, respectively. The pumping volume is measured to be 1.52 μL per pumping cycle, and the micropump can maintain the self-locking characteristic up to a pressure of 24 kPa by the latching force of 3.7 N from the actuator. The proposed energy-efficient and self-locking micropump system can be readily applicable in various applications where the reliable pumping with the low-power and low-voltage characteristics are required such as wearable drug delivery systems.

This article presents a segmented layer model (SLM) for the air-cored linear permanent-magnet synchronous motors (LPMSMs) with multiple modular stators. In the LPMSM with modular stators, the significant current-driven ripples (CDRs) are observed as the permanent magnet mover moves across the stator modules, due to the magnetic end effects. Such CDRs become more severe as the current excitation level increases. In order to correctly model the overall motor forces in the LPMSM, the analytic motor model needs to be able to capture the magnetic end effects from both the stator and mover, and also include the current-driven effects. The SLM method presented in this article divides the analytical region into several segmented layers to be able to accurately capture both the geometric-saliency- and current-driven force ripples by using layers with different fundamental spatial frequencies. The fidelity of the proposed SLM is validated both by the finite element method (FEM) and the experiments. The SLM achieves an accuracy of more than 97% and 87% compared to the FEM and experimental results, respectively, while reducing the computation time by two orders of magnitude as compared to the FEM.

This paper presents a novel 3-dimensional hybrid segmented layer model (3D HSLM) for coreless axial-flux permanent magnet synchronous motors (AFPMSMs). In the proposed 3D HSLM, the magnetic field sources are divided into the PM array and current-driven electro-magnets, which are captured by the combination of the magnetic scalar potential and vector potential models. This paper proposes a geometry function and cylindrical harmonic index modulation functions in order to correctly capture the curvature effect by the PMs and coils with arbitrary shapes and also the radial edge effect from the finite lengths of the rotor and the stator. The proposed modeling method also enables accurate estimation of the motor characteristics on the on-load conditions using the magnetic vector potential model. The fidelity of the proposed 3D HSLM is validated against the equivalent FEM models for various cases with different PM and coil shapes, in terms of the airgap magnetic fields, motor torque, and flux linkage. The comparison results show that the proposed 3D HSLM yields a modeling accuracy of more than 98 % while significantly reducing the calculation time by two orders of magnitude as compared to the FEM models.

While the electromagnetic micropump has low-voltage driving characteristic, it requires continuous energy loss in the form of Joule heating during operations, which can be significantly problematic for battery-driven applications. This paper presents a design and control method of an energy-efficient electromagnetic bi-stable actuator for low-power micropump systems in battery-driven and low-power applications such as wearable drug delivery devices. The proposed actuator design achieves the magnetic bi-stability with the PM-biased flux, reducing the required power by providing zero-power passive latching force and by enabling reciprocating motions with only a short pulsatile current excitation. We also present in this paper the energy-efficient pulse control method using a relationship of the coil voltage and the mover velocity in order to achieve robust switching motions with minimized switching energy. The low-voltage low-power characteristic of the proposed actuator and the feasibility of the control method are experimentally validated. The measured minimum voltage and switching energy are 0.43 V and 1.88 mJ, respectively. The flow volume of the fabricated micropump prototype is measured to be 1.94 µl per latching motion.