Trajectory and Conveyance Validation of a Micro Conveyor Based on a Digital Electromagnetic Actuators Array for the Micro-Factory

Micro-factories are characterized by high modularity, reconfigurability and mobility. To achieve this, the micro-factory needs a conveyor which is able to transport objects in as many degrees of freedom (DoF) as possible, executes optimal trajectories of these objects in terms of energy and precision and is robust to withstand possible malfunctions. In this article, we present the planar conveyance of objects on a digital actuation array following trajectories generated by an adapted A* algorithm. The A* algorithm exploits the predictions of a developed dynamic model of the system to find the optimal paths (in terms of energy) on the conveyor surface. The dynamic model predictions were compared to experimental measurements, obtaining low root-mean-square-errors for all conditions. Uni-dimensional conveyance tests characterized the influence of the control parameters. Then, bi-dimensional motions characterized the conveyor’s performance. From the bi-dimensional test, a position root-mean-square-error of 20 μm was measured for a 1109 μm open-loop controlled trajectory. The modular nature of the array allows easy scaling and avoiding possible malfunctioning zones, increasing the robustness of the micro-conveyor. The experimental tests demonstrate that the proposed device is an interesting alternative for the micro-factory.

A multiphysics model of processes in electromagnets and actuators of vacuum switching devices taking into ac-count contact interaction of structural elements

The purpose of the work is to improve mathematical models and algorithms of computer modeling of multiphysics processes in electromagnets and actuators of vacuum switching devices by taking into account the contact interaction of structural elements when changing their stress-strain state. In the design of modern vacuum circuit breakers and contactors, there is a significant use of electromagnetic actuators based on high-coercive hard magnetic rare earth composite materials NdFeB and SmCo. The most promising for use as drives of circuit breakers and contactors are polarized electromagnets based on the use of these high-coercive permanent magnets. However, the existing serial designs of electromagnets and actuators need to be significantly improved in order to increase reliability and service life, reduce weight and cost, further reduce energy consumption, improve the manufacturability of the mass production process. Computer simulation is proposed to be performed by the Finite Element Method in 2D formulation using commercial software products and/or software created directly for these investigations. One of the priority areas for improving mathematical models and algorithms for computer modeling of processes in the mechanical circuit of vacuum switching devices of medium and high voltage is to take into account the contact interaction of the structural elements of the devices under consideration. The next step, thanks to the use of an advanced mathematical model, is to perform a set of computational research and based on the obtained numerical results to develop recommendations aimed at creating designs of electromagnets and actuators that would meet world standards and be competitive in the world market.

Actuating Compact Augmented Reality Devices by Artificial Muscle

An artificial muscle actuator resolves practical engineering problems in compact wearable devices, which are limited to conventional actuators such as electromagnetic actuators. Abstracting the fundamental advantages of an artificial muscle actuator provides a small-scale, high-power actuating system for developing varifocal augmented reality (AR) glasses and naturally fit haptic gloves. Here, we design a shape memory alloy (SMA)-based lightweight and high-power artificial muscle actuator, the so-called compliant amplified SMA actuator (CASA). Despite its light weight (0.22 g), the CASA has a high power density of 1.7 kW/kg and an actuation strain of 300%. We show how CASA enables image depth control and an immersive tactile response in the form of AR glasses and haptic gloves whose thin form factor and high power density can hardly be achieved by conventional actuators.

Optimal Design of Magneto-Force-Thermal Parameters for Electromagnetic Actuators with Halbach Array

A magnetic levitation isolation system applied for the active control of micro-vibration in space requires actuators with high accuracy, linear thrust and low power consumption. The magneto-force-thermal characteristics of traditional electromagnetic actuators are not optimal, while actuators with a Halbach array can converge magnetic induction lines and enhance the unilateral magnetic field. To improve the control effect, an accurate magnetic field analytical model is required. In this paper, a magnetic field analytical model of a non-equal-size Halbach array was established based on the equivalent magnetic charge method and the field strength superposition principle. Comparisons were conducted between numerical simulations and analytical results of the proposed model. The relationship between the magnetic flux density at the air gap and the size parameters of the Halbach array was analyzed by means of a finite element calculation. The mirror image method was adopted to consider the influence of the ferromagnetic boundary on the magnetic flux density. Finally, a parametric model of the non-equal-size Halbach actuator was established, and the multi-objective optimization design was carried out using a genetic algorithm. The actuator with optimized parameters was manufactured and experiments were conducted to verify the proposed analytical model. The difference between the experimental results and the analytical results is only 5%, which verifies the correctness of the magnetic field analytical model of the non-equal-size Halbach actuator.

Stabilization of a cantilever pipe conveying fluid using electromagnetic actuators of the transformer type

The article presents an investigation of the stabilization of a cantilever pipe discharging fluid using electromagnetic actuators of the transformer type. With the flow velocity reaching a critical value, the straight equilibrium position of the pipe becomes unstable, and self-excited lateral vibrations arise. Supplying voltage to the actuators yields two opposite effects. First, each of the actuators attracts the pipe, thus introduces the effect of negative stiffness which destabilizes the middle equilibrium. Second, lateral vibrations change the gap in magnetic circuits of the actuators, which leads to oscillations of magnetic field in the cores and the electromagnetic phenomena of induction and hysteresis that impede the motion of the pipe. The combination of these two non-linear effects is ambiguous, so the problem is explored both theoretically and experimentally. First, a mathematical model of the system in form of a partial differential equation governing the dynamics of the pipe coupled with two ordinary differential equations of electro-magnetodynamics of the actuators is presented. Then, the equation of the pipe’s dynamics is discretized using the Galerkin procedure, and the resultant set of ordinary equations is solved numerically. It has been shown that the overall effect of actuators action is positive: the critical flow velocity has been increased and the amplitude of post-critical vibrations reduced. These results have been validated experimentally on a test stand.

Wearable Actuators: An Overview

The booming wearable market and recent advances in material science has led to the rapid development of the various wearable sensors, actuators, and devices that can be worn, embedded in fabric, accessorized, or tattooed directly onto the skin. Wearable actuators, a subcategory of wearable technology, have attracted enormous interest from researchers in various disciplines and many wearable actuators and devices have been developed in the past few decades to assist and improve people’s everyday lives. In this paper, we review the actuation mechanisms, structures, applications, and limitations of recently developed wearable actuators including pneumatic and hydraulic actuators, shape memory alloys and polymers, thermal and hygroscopic materials, dielectric elastomers, ionic and conducting polymers, piezoelectric actuators, electromagnetic actuators, liquid crystal elastomers, etc. Examples of recent applications such as wearable soft robots, haptic devices, and personal thermal regulation textiles are highlighted. Finally, we point out the current bottleneck and suggest the prospective future research directions for wearable actuators.

Modified Electromagnetic Actuator for Active Suspension System

Active suspension is a type of suspension systems which can vary its damping value in order to adjust the spring firmness in accordance with the road conditions. Real Active Suspension incorporates an external actuator which helps in raising or lowering of vehicle chassis independently at each wheel. Generally, the actuators that are used for active suspension are Hydropneumatic, Electro-hydraulic or Electromagnetic actuators. A new concept of two-way electromagnetic actuation with the help of magnetic damping is proposed in this paper, which can extend its arm on both sides to facilitate active suspension mechanism in both humps and potholes. This increases the ride quality while maneuvering not only in humps, but also in dumps. It also describes about the comparison of spring materials, sophisticated design, construction and working principle of newly proposed actuator. Catia V5 software has been used to design and simulate the actuator model, different spring materials are analyzed and their shear stress and deflections are compared.

Wearable Actuators: An Overview

The booming wearable market and recent advances in material science has led to the rapid development of the various wearable sensors, actuators, and devices that can be worn, embedded in fabric or accessories, or tattoos directly onto the skin. Wearable actuators, a subcategory of wearable technology, have attracted enormous interest from researchers in various disciplines and many wearable actuators and devices have been developed in the past few decades to assist and improve people's everyday lives. In this paper, we review the actuation mechanisms, structures, applications, and limitations of recently developed wearable actuators including pneumatic and hydraulic actuators, shape memory alloys and polymers, thermal and hygroscopic materials, dielectric elastomers, ionic and conducting polymers, piezoelectric actuators, electromagnetic actuators, liquid crystal elastomers, etc. Examples of the recent applications such as wearable soft robots, haptic devices, and personal thermal regulation textiles are highlighted. Finally, we point out the current bottleneck and suggest the prospective future research directions for wearable actuators.