BACKGROUND: Design and study of linear asynchronous motors for drives with linear or reciprocating movement of working parts is a pressing task. AIM: This work aimed to study the special aspects of determining the secondary current density of a linear asynchronous motor with a transverse magnetic flux based on the transverse fringe effect. METHODS: Mathematical modeling based on physical effects produced equations allowing to consider the nonuniform distribution of magnetic induction in the air gap when calculating the secondary current density of a linear asynchronous motor. RESULTS: Equations to determine secondary current density in different areas of the conductive part were obtained through analysis. CONCLUSION: The equations for calculating the secondary current density are based on both the nonuniform distribution of magnetic induction in the transverse direction and the relationships between the geometric dimensions of the linear motor.

This paper presents a systematic review of linear motor-based electromagnetic suspension, a key technology for reconciling vehicle comfort, handling stability, and energy consumption. The review focuses on two core areas: actuator configuration and control strategy. In configuration design, a comparison of moving-coil, permanent magnet synchronous (PMSLM), and switched-reluctance linear motors identifies the PMSLM as the mainstream approach due to its high-power density and performance. Key design challenges for meeting stringent vehicle operating conditions, such as mass-volume optimization, thermal management, and high reliability, are also analyzed. Regarding control strategy, the review outlines the evolutionary path from classical to advanced and intelligent control. It also examines the energy-efficiency trade-off between vibration suppression and energy recovery. Furthermore, the paper summarizes three core challenges for industrialization: nonlinear issues like thrust fluctuation and friction, the coupling of electromagnetic–mechanical–thermal multi-physical fields, and bottlenecks related to high costs and reliability verification. Finally, future research directions are envisioned, including new materials, sensorless control, and active safety integration for autonomous driving.

Modern industry requires high-precision control of vibrating electromechanical systems, which are widely used in many industries. Variable load modes require the drive to have good control properties while maintaining the necessary energy parameters of the technological process. The presented work substantiates the strategy for controlling a three-phase vibrating linear motor based on back electromotive force estimation, which ensures the improvement of its control properties due to an increase in the amplitude of mechanical vibrations. The operation of the motor control system is studied using a multi-physics model that combines the calculation of electric and magnetic circuits, as well as the determination of the law of mover motion depending on the forces applied to it. The mechanical scheme is represented by a lumped mass that oscillates relative to the position of mechanical equilibrium under the action of the motor electromagnetic force. Conservative and dissipative forces are represented by the corresponding stiffness and viscous friction coefficients. The load force characteristic is given by the sum of the elastic component, proportional to the mover displacement, and the viscous friction force, proportional to its velocity. The solution of this problem was carried out by the finite element method in the axisymmetric formulation, using a moving type of computational mesh, based on the equations of a quasi-stationary magnetic field in the time domain. The control system operation was simulated in two operating modes - with rectangular and sinusoidal modulation, and the electromechanical processes of the motor in a steady-state mode were calculated.

Reliable positioning performance is crucial in precision industrial automation, especially under dynamic conditions. This research focuses on examining the accuracy of a toothed belt driven linear servo motor positioning system, with the aim of identifying the main factors influencing position deviation. The system was built on a Power Belt ITO 060M shaft, controlled by an Rtelligent RS200-G servo controller and an Omron CP1L-E PLC. Position measurement was performed by a laser distance meter and a Cognex IS2000C-130-40-SR8 industrial camera, both calibrated with certified gauge blocks. The linear unit was moved to predefined points at different speeds, accelerations, and decelerations profiles and the resulting position deviation was recorded for each case. Several analytical methods were used to evaluate the collected measurement data to determine which factors have the greatest impact on positioning error. The result showed that speed significantly affected the accuracy of the system, while the effects of deceleration and acceleration were less pronounced. The study contributes to the fine-tuning of linear motion system and the targeted improvement of their performance.

Permanent magnet linear synchronous motors (PMLSMs) are main power source of many electric vehicles, which are widely used in maglev trains, light rail transit, subways and other electric trail vehicles. However, prolonged operation may induce various actuator and sensor faults, including demagnetization, wear, reduction in electromechanical constants, or decline of component performance. This will bring great threat to the safety of rail vehicles. This article addresses synchronization control of PMLSM-based dual-linear-motor synchronous-driven (DLMSD) systems under actuator and sensor faults, external disturbances, and model uncertainties. A radial basis function neural network (RBFNN) adaptive fault-tolerant control (AFTC) scheme (NN-AFTC) based on a cross-coupling structure is proposed to comply with the strong requirements for tracking precision and synchronization performance of these systems, also providing excellent fault tolerance and disturbance rejection. Specifically, AFTC compensates for actuator and sensor faults, whereas the NN controller estimates and compensates for system residual and unmodeled errors, and unknown disturbance. Comparative experiments with several latest control strategies have been conducted on an actual DLMSD platform. The obtained results provide clear evidence of the superiority and efficacy of the proposed NN-AFTC approach.

Based on the long-stator permanent magnet linear synchronous motor (PMLSM), motor structures with different pole–slot ratios are designed by changing the distribution of armature windings. A magnetic field analytical model of the motor is developed, the no-load magnetic field characteristics of the motor are calculated, and the results are compared and verified with those obtained by the finite element analysis (FEA). The influences of back-electromotive force (EMF) and armature reaction on the no-load magnetic field under different slots are studied. Through fast Fourier transform, the harmonic characteristics of the magnetic field in different structures are analyzed. Then, the cogging force and thrust characteristics generated by the motor in different structures are compared. The research results provide certain references for motor design.

This paper introduces a portable and user-friendly innovation in food processing by replacing traditional molding methods with a linear DC motor (LDM). Traditional methods, which involve manual pressing, are energy-intensive and time-consuming, reducing productivity. The proposed LDM offers a simple, cost-effective, and robust solution capable of producing constant thrust, unlike conventional LDMs that require complex and expensive control methods and are limited to short displacements. The research focuses on modelling and analyzing an LDM with constant thrust characteristics for food processing applications. The primary objective is to model the thrust using the permeance analysis method (PAM), ensuring constant thrust capability. Verification was conducted using the finite element method (FEM) and measurement results, showing a percentage difference of 1.7% and 6.5%, respectively, between PAM and the other methods. The study provides valuable guidance for designing LDMs with constant thrust capabilities, enhancing the efficiency and practicality of food processing devices.

Double-Primary With Segmented-Secondary Linear Induction Motor for Mining Industry Conveyor Systems

Design and analysis of linear haptic motor with pure magnetic spring

Abstract Kibble balances are complex electromechanical instruments that enable the determination of mass within the SI by linking it to the Planck constant h, the defining constant of the mass unit. The LNE has been developing its own Kibble balance since 2002, with the most recent improvements focusing on the implementation of a contactless linear motor for the dynamic phase and the fine adjustment of the beam’s orientation with respect to the horizontal plane for the static phase. In 2024, two mass calibration campaigns were carried out using the LNE Kibble balance: first with an iridium standard (DB1), and then with a platinum-iridium standard (W1). Both artefacts have a nominal mass of 500 g, and their masses were determined with relative standard uncertainties of 3.1·10⁻⁸ and 3.5·10⁻⁸ respectively (k = 1).

BackgroundMotor impairments are emerging predictors of amnestic mild cognitive impairment (aMCI) and dementia of the Alzheimer's type (DAT), with these groups demonstrating worse performance on metrics such as gait speed and endurance relative to cognitively normal (NC) controls (Windham et al., 2022). Racial disparities, including systemic inequities in healthcare access and chronic disease prevalence, contribute to worse motor performance in Black individuals (Blanco et al., 2012). This study examines NIH Toolbox Motor Battery (NIHTB‐MB) performance across racial and diagnostic groups (e.g., NC, aMCI, DAT), hypothesizing poorer motor performance in Black participants and linear motor decline across diagnostic categories.MethodThe sample included 557 older adults ages 65‐99 (41.1% male) from the Assessing Reliable Measurement in Alzheimer's Disease and Cognitive Aging (ARMADA) study. Participants completed NIHTB‐MB measures of balance, gait speed, endurance, grip strength, and fine motor dexterity. After controlling for age and sex, racial differences between Black (n = 123) and White (n = 232) NC participants were assessed using multiple linear regression, while diagnostic group differences (NC: n = 355; aMCI: n = 137; DAT: n = 65) were examined using ANCOVA with post‐hoc comparisons.ResultMotor performance declined with age across all measures (p < .001). Black participants scored higher than White on Standing Balance, t(69)=‐2.91, p = .005, with no other racial differences in motor performance. Across diagnostic groups, individuals with DAT performed worse than NC on balance (p = .007), dominant/non‐dominant grip strength (p = .005/.05), dominant/non‐dominant dexterity (p = .003/< .001), and endurance (p < .001) measures. Participants with DAT also performed worse than those with aMCI on dominant/non‐dominant dexterity (p = .049/< .001), endurance (p = .002), and balance (p = .05). Gait speed did not differ across groups, and no motor differences were observed between NC and aMCI groups.ConclusionContrary to expectation, Black older adults exhibited better balance than White, though missing values were highest for this measure. Motor decline was primarily observed in individuals with DAT, who performed worse on fine motor dexterity, grip strength, endurance, and balance compared to NC and aMCI groups. These findings suggest that motor difficulty may serve as a marker of DAT, while NIHTB‐MB performance in aMCI remains largely preserved. Thus, more sensitive metrics, such as dual task conditions, may better characterize early motor changes in aMCI.

Abstract This paper investigates the disturbance‐observer‐based finite‐time fault‐tolerant control problem for an output‐constrained permanent magnet linear motor system characterized by unknown dead‐zone inputs and uncertain control coefficients. To address this challenge, a set of novel parameter functions, along with corresponding adaptive control laws, are developed as the primary means to estimate the unknown dynamic effects. Furthermore, a radial basis function neural algorithm is used to approximate the nonlinear composite friction where a proportional‐differential‐based gradient descent accelerator is embedded to fasten the convergence speed of the neural network weight . Additionally, uncertain disturbances are mitigated using a modified disturbance observer equipped with an adaptive compensation law, which effectively eliminates compensation deviation. In conclusion, we present rigorous proof procedures, supported by extensive simulation experiments, to validate the effectiveness and feasibility of the proposed theory.

Analysis of magnetomotive force harmonics and inductance calculation for star-delta hybrid winding permanent magnet linear motors

Electromechanical suspension has the advantages of rapid response, high efficiency, and strong integration. As the actuator for electromechanical suspension, rotary motors exhibit higher efficiency compared to linear motors. However, the motion conversion mechanisms are required to apply rotary motors in vehicle suspensions. The motion conversion mechanism of the connecting rod rocker arm electromechanical suspension reduces the shock during reversal and transmits smooth torque. However, the dynamic model of the connecting rod rocker arm electromechanical suspension is challenging to develop accurately due to the strong nonlinearity of the mechanism. This paper proposes a fundamental dynamic modeling approach for the connecting rod rocker arm electromechanical suspension based on kinematics and mechanics analysis. The complex-vector method and the dynamic-static analysis method are employed in the proposed modeling approach to analyze the kinematics and mechanics characteristics of the electromechanical suspension. Simulations and small-scaled prototype tests are conducted to verify the effectiveness of the proposed modeling approach. In addition, a linearization control system of permanent magnet synchronous motor (PMSM)-based connecting rod rocker arm electromechanical suspension is preliminarily investigated.

Micro-robots hold promise for complex tasks such as fault diagnosis and emergency response, where conventional detection methods are limited by size and maneuverability constraints. However, their adaptability in complex environments remains insufficient owing to reduced propulsion efficiency. This study proposes a 7.5mm micro-robot actuated by an electromagnetic linear motor and integrated with tree frog-inspired bionic feet (MRBF) to enhance traction and locomotion performance. The bionic feet are fabricated via angled photolithography to realize the microstructured design. The integration of bionic feet enables the MRBF to reach a maximum velocity of 39 body lengths per second (BLs-1) on dry surfaces and 28.5 BLs-1 on wet surfaces, representing improvements of 75% and 40%, respectively, compared to the non-bionic version. The MRBF can also climb inclines of up to 21.8°, nearly doubling its original climbing limit of 11°, demonstrating a considerably enhanced slope-climbing capability. A dual-MRBF system is specifically designed to achieve rapid and controllable turning, attaining angular velocities of ≈311°s-1. When equipped with a micro-camera, MRBFs are successfully deployed for in situ blade inspection within the confined intake duct of a micro-aero-engine. This strategy provides a scalable framework for adaptive, high-performance systems in aerospace inspection, soft robotics, and autonomous sensing.

Optimal Design and Analysis of Permanent Magnet Linear Synchronous Motor Considering Cogging Force

Two types of biosensors based on electric cell-substrate impedance sensing (ECIS) technique will be presented: (1) afield-portable toxicity device with live mammalian cells as biorecognition element and (2) a stretchable ECIS sensor for mammalian cell proliferation studies [1]. The first device provided rapid assessments of water toxicity, to increase the security of drinking water. This device included a combination of two sensors, that were able to monitor the mammalian cell attachment and viability when exposed to toxicants. One of the sensors was a quartz crystal microbalance (QCM) resonator that was integrated with the ECIS sensing technique in a single device. Both techniques; the resonant frequency measurements and ECIS measurements were demonstrated to characterize in real time the attachment and viability of the endothelial cells exposed to different types of toxicants. Bovine aortic endothelial cells (BAECs) were used in this research, because of their ability for long-term survival. The device was fabricated in the Nano/Microfabrication technology clean-room at The City College of New York (CCNY) [2, 3]. Impedance values and resonant frequency values were recorded in real-timely for several hours after introducing ammonia toxicant. According to our measurements, when exposed to ammonia with the concentration of 10Mm, the BAECs become apoptotic. When the cells cultured on this hybrid sensor were exposed to toxicant and were apoptotic the impedance values were minimal since the apoptotic cells lost their dielectric properties of the membrane. Apoptotic cells also become detached from the QCM electrode and the resonant frequency increased. In this project for the first time these two techniques; resonant frequency measurements and ECIS measurements were combined in a single device. Dr. I. Voiculescu received a US patent for this research [3]. The device was based on the innovative employment of the upper QCM electrode as the working electrode for ECIS technique. This novel device had higher accuracy of detection, compared to a device with only a single sensing method. For rapid studies of water toxicity, the simultaneous responses from two different sensors will confirm the quality of the water and will offer higher detection security.The second research topic is in stretchable electronics area. This research demonstrated that the ECIS technique could be included in a stretchable substrate [4]. This is the first time when ECIS electrodes were fabricated on a stretchable substrate and ECIS measurements on mammalian cells exposed to cyclic strain of 8% were successfully demonstrated. BAECs cells were used to evaluate the physiological functions influenced by mechanical stimulus, because they undergo in vivo cyclic physiologic elongation produced by the blood circulation in the arteries. The BAEC were cultured on the ECIS sensor mounted on a linear motor and kept inside a cell culture incubator. The impedance data was acquired at the end of each stretch/release cycle. Microelectrodes fabricated from gold (Au) on the stretchable membrane were used to record the impedance values of endothelial cell membranes during the proliferation process. The device had miniature dimensions. The impedance responses from the sensors with and without 8% stretch during the first 70 hours after BAECs cell seeding with low density were recorded. The impedance response from the 4 ECIS sensors with BAECs cell was related to the cell number and densities. Endothelial cells exhibited an increase in proliferation in response to elongation and the experiments demonstrated this behavior. This research is novel, because this is the first time that ECIS electrodes were fabricated on a stretchable polydimethylsiloxane (PDMS) substrate and ECIS measurements were performed on mammalian cells exposed to cyclic strain of 8%. Dr. Voiculescu received a US patent for this research [5]. In summary: The ECIS technique is a powerful technique to monitor in real-time cell viability, attachment, proliferation and apoptosis.

Optimal design of a permanent magnet linear synchronous motor for thrust ripple reduction based on machine learning

The voice coil motor (VCM) represents a unique type of direct-drive motor, named for its operational principle. Its working mechanism resembles that of a loudspeaker diaphragm, wherein a voice coil generates motion through the application of a controlled electric current. The fundamental principle involves a current-carrying conductor producing force within a magnetic field, with the magnitude of the force directly proportional to the input current. The resulting motion is typically linear or follows an arc trajectory. As a distinct variant of linear motors, the VCM features a coreless design and operates without a traditional transmission system. This structural simplification enhances system compactness and reduces mechanical complexity. Additionally, VCMs offer numerous advantages, including high stiffness, rapid response, silent operation, excellent linearity, and the absence of cogging and pulsation. These attributes make them well-suited for short-stroke, high-frequency, and highly precise reciprocating movements, contributing to their widespread use in high-precision servo applications. While the removal of transmission components improves efficiency and design simplicity, it also increases the system’s sensitivity to external disturbances and variations in load. Moreover, challenges such as low thrust density, mechanical resonance, and the difficulty of developing accurate system models hinder the performance of VCMs in precision control scenarios. This paper focuses on the analysis of several prominent control strategies for VCMs, detailing their operating principles and characteristics. It also summarizes their practical application domains, aiming to provide insight into the implementation of VCMs in advanced servo systems.

Edible robotics offers novel applications in which actuators play a key role. However, most existing edible actuators rely on 3D structures that require complex and laborious fabrication processes, hindering rapid prototyping and deployment. To address this issue, this study explores the use of planar configurations, specifically pouch motors, for edible actuators. These actuators are lightweight and can be fabricated quickly via heat sealing. Two types of edible pouch motors are developed using an agar‐based film: linear and angular actuators, and their actuation performances are characterized. The linear pouch motor (1.16 g) exhibits a strain of 30.6% and a force of 13.6 N at an input pressure of 5 kPa, demonstrating performance comparable to nonedible counterparts and durability up to 1000 actuation cycles. The angular pouch motor (0.42 g) achieves a rotation angle of 121.3° at 10 kPa and a torque of 0.11 N m at 16 kPa. Experimental results closely align with theoretical predictions. Furthermore, an edible pouch gripper (2.6 g) successfully performs a pick‐and‐place operation with a 97.0 g potato and fully dissolves in hot water while maintaining its grip. These findings validate the feasibility of planar edible actuators and highlight their potential for advancing future edible robotics.