Electromagnetic Linear Actuator Research Articles

A Millimeter‐Scale Micro Crawling Robot with Fast‐Moving Driven by a Miniature Electromagnetic Linear Actuator

The micro crawling robot exhibits significant potential applications in various fields such as fault detection, disaster relief, and environmental monitoring. This article introduces a high‐performance millimeter scale crawling robot driven by a miniature electromagnetic linear actuator (MELA) with a body length of 5–6 mm and a mass of 80 mg. In this article, the working principle of the micro robot is analyzed and validated, and the influence of current, frequency, and angle α between the direction of actuator's force and the crawling surface on the crawling speed are analyzed through experiments. Results show that the optimal α ranges from 50° to 55°, and a specific current and frequency are identified to achieve maximum crawling speed for robot with particular α. When α is 50°, with a current of 300 mA and a frequency of 200 Hz, the robot reached the maximum speed of 20.2 Body Length s−1(BL s−1). The proposed robot can crawl at 12 BL s−1 with a load of 110 mg, and support a maximum load of 400 mg. Additionally, the robot demonstrated diverse capabilities such as climbing on a 10° slope with a load of 110 mg, jumping on a 1 mm obstacle, and crawling on surfaces of various materials.

Energy-based high frequency oscillation control of linear drives

Linear electromagnetic actuators realizing periodic oscillations have gained significant importance in the compressor and pump technology. This is due to the need of compact drive units to increase the power density of modern pumps and compressors. This work presents an energy-based control approach for harmonic oscillations of linear electromagnetic drives and analyzes the functionality and performance of the oscillation control for periodic actuator movements up to 250 Hz. To obtain a more robust control behavior, the control structure needs to be decoupled, with an amplitude and phase component using a periodical harmonic carrier function. This approach avoids a standstill of the actuator by constantly triggering an oscillation at the fundamental frequency of the mechanical system. The presented control approach is especially beneficial for oscillatory systems which need to adapt their oscillation frequency to mechanical loads.

Structural and Material Analysis of an Electromagnetic Actuator for Pressure Control in an Internal Combustion Engine

The article describes the process of selecting the design parameters of the electromagnetic actuator, which was used to regulate the compression pressure in the cylinder of an internal combustion engine. The electromagnetic actuator was installed in the timing system of a single-cylinder internal combustion engine, which forced its basic design parameters in terms of force and frequency of operation. For the electromagnetic actuator in question, field calculations of the esign variants of the linear electromagnetic actuator for two types of materials were conducted. The finite element method was applied to the computer-aided design of electromagnetic actuators. The influence of the magnetic circuit and the dimensions of the windings on the distribution of the magnetic field were analyzed. The thickness and height of the magnetic field induces, and the dimensions of the stator poles have been changed while maintaining the same external dimensions of the actuator for design reasons. All this work was aimed at improving the performance of the internal combustion engine in terms of improving efficiency in terms of partial engine loads. In this area, the internal combustion engine is characterized by low efficiency, significantly deviating from the maximum, and at the same time, during normal operation of vehicles is the area most often exploited.

Multidisciplinary optimization and motion control method of electromagnetic linear actuator for electro-hydrostatic system

Multidisciplinary optimization and motion control method of electromagnetic linear actuator for electro-hydrostatic system

Design, Modeling, and Simulation of a Novel Electromagnetic Linear Actuator for Linear Motion

Design, Modeling, and Simulation of a Novel Electromagnetic Linear Actuator for Linear Motion

Thermal characteristics analysis of a new compound electromagnetic linear actuator based on multi-physical coupling method

The new compound electromagnetic linear actuator (CELA) features high energy efficiency, high power ratio, fast response and high precision. However, it is compact in structure due to volume constraints. Also, there are significant internal electrical, magnetic and thermal coupling effects and the temperature rise problem is prominent. In this paper, the electric-magnetic-thermal coupling mechanism of multiple physical fields inside the CELA was analyzed first. Considering the influence of different driving modes on energy consumption, the theoretical model of energy consumption was built based on iron loss separation. The heat transfer mechanism and process of the mechanism were studied with energy consumption as heat source. Considering the influence of thermal characteristics on the material properties, an accurate numerical model with electric-magnetic-thermal multi-physical field bidirectional coupling was established. The energy consumption distribution and the transient change characteristics of the temperature distribution with time and space were studied quantitatively under different driving modes and different operating conditions of the CELA. A test platform for energy consumption and temperature rise was established to verify the accuracy of theoretical analysis and simulation. The results showed the test and simulation results were in good agreement under typical operating conditions, with the error less than 2%.

Design and Analysis of Brake-by-Wire Unit Based on Direct Drive Pump–Valve Cooperative

Aiming at the requirements of distributed braking and advanced automatic driving, a brake-by-wire unit based on a direct drive pump–valve cooperative is proposed. To realize the wheel cylinder pressure regulation, the hydraulic pump is directly driven by the electromagnetic linear actuator coordinates with the active valve. It has the advantages of rapid response and no deterioration of wheel side space and unsprung mass. Firstly, by analyzing the working characteristics and braking performance requirements of the braking unit, the key parameters of the system are matched. Then, in order to ensure the accuracy of the simulation model, the co-simulation model of the brake unit is established based on the Simulink-AMESim co-simulation platform. Then, the influence law of key parameters on the control performance is analyzed. Finally, the experimental platform of the brake unit is established. The accuracy of the co-simulation model and the feasibility of the brake-by-wire unit based on direct drive pump–valve cooperative are verified through the pressure control experiment and ABS simulation, which shows that the braking unit has good dynamic response and steady-state tracking effect.

Nonlinear electromagnetic force analysis and compensation control of electromagnetic linear actuator

Nonlinear electromagnetic force is a common phenomenon in electromagnetic linear actuators (EMLA). This nonlinearity limits the application in high-precision control systems. For facilitating the controller design, the influencing factors of nonlinear electromagnetic force were analyzed, and the quadratic polynomial with unknown weights was designed to approximate the nonlinear relationship among electromagnetic force, excitation current and displacement. An adaptive integral robust control algorithm based on electromagnetic force compensation (AIRC-FC) was designed, which combined the adaptive control law of electromagnetic force nonlinear compensation, stable feedback and error signal continuous integral robust control. The tracking performance and the adaptability of the EMLA with and without compensation control were analyzed under different loads. The results show that AIRC-FC improve the tracking performance of the EMLA effectively, and maintain high control accuracy under different loads.

Electromagnetic Design and Analysis of Inertial Mass Linear Actuator for Active Vibration Isolation System

Underwater radiated noise from anthropogenic structures must be reduced to protect the marine environment. Active vibration isolation that can reduce noise generated from vibration sources by providing counteracting forces can solve this issue. This paper presents a 120 N class electromagnetic inertial mass linear actuator for an active vibration control system in a large ship. The proposed actuator is operated based on the Lorentz force, also known as electromagnetic force. To achieve a high thrust force to weight ratio, a permanent magnet with outer radial magnetization is used. In order to design and analyze the proposed model, a simple magnetic equivalent circuit analysis was first conducted to achieve an appropriate force, and its value was compared and verified with the magnetostatic finite element method. The dynamic characteristics of the actuator were then evaluated, and the performance was analyzed at various operating frequency points. The bobbin housing supporting the coil causes an eddy current loss due to materials with electrical conductivity. As a result, the damping force is generated by the reduction in magnetic flux, and the control force tends to decrease.

Loss analysis of a novel compound electromagnetic linear actuator under different operating modes and working conditions

As an important actuator component, the electromagnetic linear actuator has a significant impact on the performance of fully flexible variable valve trains. Aiming at the shortcomings of the conventional moving coil electromagnetic linear actuator (MCELA) with low force density and insufficient end-passive self-holding ability, a novel compound electromagnetic linear actuator (CELA) integrating the advantages of MCELA and the moving iron electromagnetic linear actuator (MIELA) was proposed in this work. The CELA has two operating modes, including single drive mode and cooperative drive mode, and its loss variation is different from that of the single MCELA or MIELA. Firstly, the current and displacement curves under different operating modes were obtained through experiments, which were then used as the excitation source to quantitatively analyze the copper and iron losses under different working conditions by means of 3D finite element simulation. The loss distribution and ratio of CELA under typical operating conditions were discussed in detail. The effects of stroke and valve opening duration on CELA losses were analyzed. The results show that there are significant differences in the loss variation rules between the two operating modes, the losses increase as the working stroke increases in single drive mode. In the cooperative drive mode, the losses are much greater than in the single drive mode, with the losses decreasing in the initial stage and then increasing as the stroke increases. None of the valve opening durations had a significant effect on losses. This study provides a reference for loss studies of other novel electromagnetic linear actuators.

Design and simulation analysis of electric needleless syringe

A new design of a needleless syringe based on a moving-coil electromagnetic linear actuator drive is proposed to address the problems of the uncontrollable driving force and bulky structure commonly found in current commercial needleless syringes. The structural parameters of the moving-coil electromagnetic linear actuator with the electromagnetic driving force at different current strengths are obtained using the finite element analysis method. The results of jet stagnation pressure and jet velocity were obtained by MATLAB numerical calculation and CFD jet simulation. The process of 0.1 ml drug diffusion under the skin at a current size of 40 A was simulated. The results show that the jet stagnation pressure at the nozzle is 32 MPa, the jet velocity is 246 m/s, and the jet diffusion depth reaches 15 mm under the maximum driving force condition. The output electromagnetic force of the moving-coil electromagnetic linear actuator in this scheme is proportional to the current’s magnitude, and the actuator’s small size allows it to be used as a driving component of a hand-held needleless syringe.

Simulation Study on Direct-Drive Compressor with Electromagnetic Linear Actuator

In order to enhance compressor efficiency and meet the requirements of energy conservation and environmental protection, this study designed a direct-drive compressor with an electromagnetic linear actuator. Starting with the structural design and performance analysis of the linear compressor, the working process of the moving-coil linear compressor was analyzed. The basic performance of the designed moving-coil linear motor was simulated and analyzed using the Maxwell software, while the overall performance of the linear compressor was simulated and analyzed using the Simulink software to verify the feasibility of controlling a linear compressor via the direct drive of a linear motor.

Feedback and Control of Linear Electromagnetic Actuators for Flapping Wing MAVs

We present a method for generating feedback and controlling multi-coil linear electromagnetic actuators for flapping wing systems. This has been achieved with a system capable of self-lifting, constructed using 3D-printed structures and miniaturised electromagnetic actuators with a combined weight of 3.07 g. Combining multiple magnets and coils into a single actuator with onboard feedback sensors has improved power densities upon existing linear electromagnetic systems present in the literature. The use of closed-loop control of the dynamics of the flapping profile allows for independent control of both flapping frequency and amplitude, which is differentiated from open-loop and resonance-based systems. This change will allow relatively precise control over the flapping dynamics of future systems while improving actuation efficiency.

Design of an Improved Active Disturbance Rejection Control Method for a Direct-Drive Gearshift System Equipped with Electromagnetic Linear Actuators in a Motor-Transmission Coupled Drive System

In this study, a type of direct-drive gearshift system integrated into a motor-transmission coupled drive system is introduced. It used two electromagnetic linear actuators (ELAs) to perform gearshift events. The adoption of ELAs simplifies the architecture of the gearshift system and has the potential to further optimize gearshift performance. However, a number of nonlinearities in the gearshift system should be investigated in order to enhance the performance of the direct-drive gearshift system. An active disturbance rejection control (ADRC) method was selected as the principal shifting control method due to the simple methodology and strong reliability. The nonlinear characteristics of the electromagnetic force produced by the ELA were subsequently reduced using the inverse system method (ISM) technique. The ADRC approach also incorporated an acceleration feedforward module to enhance the precision of displacement control. The extended state observer (ESO) module used a nonlinear function in place of the original function to improve the ability to reject disturbances. Comparative simulations and experiments were carried out between the ADRC method and improved ADRC (IADRC) method. The outcomes demonstrate the effectiveness of the designed control method. The shift force fluctuates less, and the shift jerk decreases noticeably during the synchronization procedure. In conclusion, combined with the optimized IADRC method, the direct-drive gearshift system equipped with ELAs shows remarkable gearshift performance, and it has the potential to be widely used in motor−transmission coupled drive systems for EVs.

Adaptive disturbance observer-based improved super-twisting sliding mode control for electromagnetic direct-drive pump

In this study, to enhance the frequency-flow characteristics of the novel electromagnetic direct-drive pump (EDDP). An adaptive disturbance observer-based improved super-twisting sliding mode control (ISTSMC-ADOB) is proposed to address the problem in which the response quality is deteriorated by factors such as parameter mismatch and disturbance. An adaptive disturbance observer (ADOB) is designed to achieve adaptive compensation, avoid the use of high-gain feedback, and extend the applicability of the conventional disturbance observer. An improved super-twisting sliding mode control (ISTSMC) based on the fast terminal sliding mode algorithm is designed to ensure faster convergence of the error in finite time. By combining the ADOB with the ISTSMC, the conservative parameter selection of the sliding mode control (SMC) is avoided, and the accuracy and robustness are further strengthened. The stability is analyzed based on Lyapunov. The results show that the proposed method effectively improves the steady-state accuracy, response speed, and robustness in trajectory tracking of the electromagnetic linear actuator for the EDDP. This further enhances the frequency-flow characteristics of the system.

Dynamic performance of linear electromagnetic actuators in a stray magnetic field: theoretical analysis and experimental verification

Linear electromagnetic actuators (LEAs) are widely used in tokamaks, but they are extremely sensitive to and are prone to fail in a high-strength stray magnetic field (SMF), which is usually a concomitant with tokamaks. In this paper, a multi-physics coupling analysis model of LEA, including magnetic field, electric circuit and mechanical motion, is proposed, and the dynamic characteristics of LEAs in SMFs are studied in detail based on the proposed model. The failure mechanism of LEAs in SMFs is revealed, and the influence of SMFs on the dynamic performance of LEAs is studied and quantified. It is shown that the failure threshold of the LEA selected in this work under the rated condition is 27 mT and 14 mT in the positive and negative direction, respectively. Under a typical SMF of 10 mT in the negative direction, the closing time of the LEA will be extended by 40%, while its opening time will be shortened by about 10%. Experimental tests are also conducted, which verify the validity of the proposed model and the analysis results. This paper provides a basis for the diamagnetic optimization design of LEA, and it is of great significance to ensure the reliable operation of the tokamak.

A drug delivery device concept using a miniature tubular linear electromagnetic actuator: design, modeling and experimental validation

A drug delivery device concept using a miniature tubular linear electromagnetic actuator: design, modeling and experimental validation

A long-stroke planar linear actuator equipped with magnetic guide

This paper introduces the design, fabrication and characterization of a micro electromagnetic linear actuator integrated with magnetic guide. The actuator consists of a slider, a stator and a magnetic guide. A magnetic guide is used to replace the mechanical rail of conventional linear actuator to ensure the linear motion and to avoid friction. The purpose of this paper is to study the influence of magnetic guide on the dynamic characteristics of electromagnetic linear actuator and measuring techniques for micro-actuators. To test the resistance to motion and output thrust force of the actuator, a cantilever type force sensor is proposed, which can measure the small force in ∼mN order, and the measurement error is less than 3%. Using this sensor, the output thrust measured is higher than 10 mN when 1 A current is applied, and the friction force of the actuator measured is about 7.73 mN. Two-phase square wave and sine wave current are used to drive the actuator, the minimum driving current and frequency of the actuator are less than 0.1 A and 1 Hz respectively. The actuator attains a maximum stable moving speed of 0.15 m s−1 with the input signal frequency of below 250 Hz. In addition, the anti-interference capability of the actuator is evaluated through simulations and experiments. These results show that the actuator can bear an interference 45 times its own gravity in the directions that are perpendicular to the moving freedom, and can adjust the direction of motion automatically when the rotation angle in three orthogonal directions is less than 6°.

Failure Analysis of Linear Electromagnetic Actuators Under Disturbing Magnetic Field

Linear electromagnetic actuators (LEAs), operated by electromagnetic action, are widely used in various applications, such as switches and solenoid valves. Since it operates on the principle of electromagnetic attraction, it is very sensitive to magnetic field. LEA may fail under the impact of disturbing magnetic field (DMF), thus threatens the stability of the whole system. As the magnetic field around tokamak is very strong, it is of great importance to evaluate the behavior of LEAs under DMF. This article presents the analysis of two different types of LEAs in DMFs. Based on the finite element method, the influences of DMF on the two LEAs are analyzed, and both the opening and closing processes are considered. Analyses show that the piston-type LEA may fail to act under DMF, while the plate-type LEA may malfunction even it is not energized. Based on the analysis, the failure mechanism is revealed, and the failure thresholds of the two LEAs are also quantified. The experimental verifications are carried out, which are in good agreement with the simulation results. The analysis model and the main conclusions presented in this article are of great significance to guide the antimagnetic field design of LEAs and ensure their reliable operations in tokamakxs.

Refined Modeling Method and Analysis of an Electromagnetic Direct-Drive Hydrostatic Actuation System

The hydrostatic actuation system based on linear actuators improves the complex piston force and long transmission path of the traditional electro-hydrostatic actuator (EHA). However, new nonlinear factors in the linear actuator and direct-driven piston are introduced into the system, which present challenges to system modeling and control. To improve the accuracy of system performance prediction, this paper analyzed the working characteristics of an electromagnetic direct-drive hydrostatic actuation system (EDHAS). A dynamic model of the electromagnetic linear actuator including the LuGre friction model was established. The high-pressure internal leakage of the direct-drive pump was described by an inclined eccentric leakage model. The Karnopp friction model was applied to solve the problem of switching between viscous and sliding friction in a cylinder. The hydraulic components model was established based on AMESim, and the electromagnetic linear actuator model and the system controller model were established in Matlab/Simulink, to establish a refined electromechanical–hydraulic co-simulation model of the EDHAS with electromagnetic, mechanical, hydraulic, and control coupling. A system performance test platform was built. The simulation results of the direct-drive piston displacement, the system pressure, the system flow rate, and the cylinder displacement match well with experimental results, which verifies the validity and accuracy of the refined modeling method.