The Research on Soft Pneumatic Actuators in Italy: Design Solutions and Applications
Experimental Study on the Working Characteristics of Tri-Electrode Plasma Actuator Utilizing a Combination of Corona and Barrier Discharges
Design and Test of an Active Pneumatic Soft Wrist for Soft Grippers

Journal Description

Actuators

Actuators is an international, peer-reviewed, open access journal on the science and technology of actuators and control systems published monthly online by MDPI.

Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, and other databases.
Journal Rank: JCR - Q2 (Instruments and Instrumentation) / CiteScore - Q2 (Control and Optimization)
Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 14.6 days after submission; acceptance to publication is undertaken in 2.8 days (median values for papers published in this journal in the second half of 2022).
Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.

Impact Factor: 2.523 (2021); 5-Year Impact Factor: 2.944 (2021)

Imprint Information Journal Flyer Open Access ISSN: 2076-0825

Latest Articles

Open AccessArticle

Design and Experimental Characterization of Artificial Neural Network Controller for a Lower Limb Robotic Exoskeleton

Chih-Jer Lin

and

Ting-Yi Sie

Actuators 2023, 12(2), 55; https://doi.org/10.3390/act12020055 (registering DOI) - 27 Jan 2023

Abstract

This study aims to develop a lower limb robotic exoskeleton with the use of artificial neural networks for the purpose of rehabilitation. First, the PID control with iterative learning controller is used to test the proposed lower limb robotic exoskeleton robot (LLRER). Although the hip part using the flat brushless DC motors actuation has good tracking results, the knee part using the pneumatic actuated muscle (PAM) actuation cannot perform very well. Second, to compensate this nonlinearity of PAM actuation, the artificial neural network (ANN) feedforward control based on the inverse model trained in advance are used to compensate the nonlinearity of the PAM. Third, a particle swarm optimization (PSO) is used to optimize the PID parameters based on the ANN-feedforward architecture. The developed controller can complete the tracking of one gait cycle within 3.6 s for the knee joint. Among the three controllers, the controller of the ANN-feedforward with PID control (PSO tuned) performs the best, even when the LLRER is worn by the user and the tracking performance is still very good. The average Mean Absolute Error (MAE) of the left knee joint is 1.658 degrees and the average MAE of the right knee joint is 1.392 degrees. In the rehabilitation tests, the controller of ANN-feedforward with PID control is found to be suitable and its versatility for different walking gaits is verified during human tests. The establishment of its inverse model does not need to use complex mathematical formulas and parameters for modeling. Moreover, this study introduces the PSO to search for the optimal parameters of the PID. The architecture diagram and the control signal given by the ANN compensation with the PID control can reduce the error very well. Full article

(This article belongs to the Special Issue Actuators in Robotic Control: Volume II)

Open AccessArticle

Armature Structure Optimization of Annular Multipole Solenoid Valves Based on Electromagnetic Force Distribution

and

Actuators 2023, 12(2), 54; https://doi.org/10.3390/act12020054 - 26 Jan 2023

Abstract

To improve the dynamic response speed of high-speed solenoid valves in electric fuel injection systems of marine diesel engines, a numerical simulation model of the solenoid valve is described in this paper. The accuracy of the simulation model was verified on the test bed of the solenoid valve. The effect of the punch position and the size of the dynamic response of the solenoid valve were investigated by using the distribution law of the electromagnetic force in the armature. The results of the test showed that armature drilling in the inter-yoke zone can optimize the solenoid closing response time, but it has little impact on the solenoid opening response time. From this rule, two groove schemes were further designed. Through comparison and calculation, it can be concluded that the fan groove scheme is better than the trapezoidal groove scheme, and that the opening and closing response times of the solenoid valve should be targeted in order to multi-target optimize the fan groove geometric parameters and the armature thickness. The results show that after optimization, the weight of the motion part is reduced by 21.6%, the opening response time of the solenoid valve is reduced by 11.1%, and the closing response time is reduced by 30.0%. While reducing the oil film damping of the armature motion, the overall dynamic response characteristics of the solenoid valve are improved. Full article

(This article belongs to the Section Precision Actuators)

Open AccessArticle

Highly Sensitive Inertial Micro-Switch for Achieving Adjustable Multi-Threshold Acceleration

Jufeng Deng

Dian Song

and

Shijie Su

Actuators 2023, 12(2), 53; https://doi.org/10.3390/act12020053 - 26 Jan 2023

Abstract

An inertial micro-switch with multi-threshold acceleration detection capability has been proposed, taking advantage of electromechanical coupling behavior. A mathematical model of electromechanical coupling behavior was established to display the dependence of highly sensitivity on pull-in characteristic and show the ability to detect threshold acceleration by controlling the voltage applied to the inertial micro-switch. The capability of sensitivity and detection that was described in mathematical model was implemented to occur at the inertial switch and showed agreement with that of a simulation. Inertia switches that were comprised of various microstructures with dimensions ranging 3.5 µm from 180 µm were manufactured by means of the micro-electro-mechanical system (MEMS) manufacturing process, and their functions were evaluated by a dropping system. The control method related to the manufacturing of inertial switches was obtained by analyzing the effect of the structural parameters of the inertial switch on threshold voltage and threshold acceleration, resulting in a relatively small error between simulation and experiment. The inertial micro-switch showed high sensitivity to achieving the pull-in effect at 30 V, sense multi-threshold acceleration ranging from 500 g to 2000 g in 2.46 ms and provided enough time for outputting the acceleration signal. Furthermore, the multi-threshold acceleration can be adjusted by controlling the voltage applied to inertial micro-switches. In addition, other functions of inertial micro-switches, such as lower residual stress, high recoverability, and repeatability, have been displayed. Full article

Open AccessArticle

Impact Force Analysis in Inertia-Type Piezoelectric Motors

Burhanettin Koc

and

Bülent Delibas

Actuators 2023, 12(2), 52; https://doi.org/10.3390/act12020052 - 26 Jan 2023

Abstract

In an inertia-type motor, a piezoelectric multilayer actuator is espoused to a transient vibration velocity as high as 1.0 m/s during slip time. This vibration velocity makes the inertia-type motors dynamic but not quasi-static. We propose a kinetic model to describe the condition under which slippage can occur between a slider and a stator. The transient current absorbed by the multilayer actuators in a stator during slip time defines the slippage behavior of the slider. A new thickness-mode force factor expression (A₃₃), which is a relation between the transient current and the transient vibration velocity, is described in electrical domain. Impact force acting on a friction coupler produced by the actuators in the stator is proportional to the rate of change in the transient current during the sliding time. Additionally, we present the structure and characteristics of a two-phase inertia-drive-type piezoelectric motor, on which the proposed model was evaluated. Driving the multilayer actuators with truncated and mirrored sawtooth signals enhances the system dynamics. As one actuator expands and the other shrinks, their respective hysteretic nonlinearities are canceled. The motor operating frequency can be as great as 30 kHz and typically load characteristics are unloaded velocity greater than 16.0 mm/s and generated force higher than 3.0 N. Full article

(This article belongs to the Special Issue Piezoelectric Actuators—A Special Issue in Honor of Prof. Dr. Kenji Uchino)

Open AccessArticle

Handshake Feedback in a Haptic Glove Using Pouch Actuators

and

Actuators 2023, 12(2), 51; https://doi.org/10.3390/act12020051 - 24 Jan 2023

Abstract

In this paper, we propose and demonstrate a haptic device with liquid-pouch motors that can simulate a handshake. Because handshakes involve contact of the palms or soft skin, handshake simulation requires the haptic device to provide pressure onto specific areas of the palm with soft contact. This can be achieved with thermally driven liquid-pouch motors, which inflate and deflate when a low-boiling-point liquid, here Novec ™ 7000, evaporates and condenses, respectively. Due to the simplicity of the soft actuator system, this haptic glove is lightweight and conformable. To design the haptic glove, we experimentally investigated the contact region and strength in handshakes, which led to an optimal number, size and position for the liquid-pouch motors. Sensory experiments with human subjects verified that the designed haptic glove successfully simulated handshakes. Full article

(This article belongs to the Special Issue Soft Actuators and Robotics)

Open AccessArticle

Experimental Investigations of Partially Valve-, Partially Displacement-Controlled Electrified Telehandler Implements

David Fassbender

Christine Brach

and

Tatiana Minav

Actuators 2023, 12(2), 50; https://doi.org/10.3390/act12020050 - 22 Jan 2023

Abstract

The next generation of electrified heavy-duty mobile machines (HDMMs) requires more efficient hydraulic systems—to save energy and to compensate for the limited capacities of available mobile electric energy sources. This study is experimentally demonstrating the functionality, dynamic performance, and efficiency of such a more efficient but also cost-effective system. The demonstrator is a conventional nine-tonne telehandler that has been transformed by replacing the diesel engine with an electric machine (EM) and changing the boom function from valve to displacement control. Since the system control and the resulting dynamics are not trivial, key aspects of it are explained in the paper. With the functional system, achievable consumption reductions could be obtained by measuring five different representative work cycles repeatedly and comparing the average consumption values to the consumption of a purely valve-controlled but also electrified reference version. In four of five cycles, an average reduction of 21–31% was achieved, which confirms the simulation results from previous studies and the effectiveness of the concept. However, one cycle—characterized by serial movements and longer breaks of the boom movement—showed a reduction of only 3% and that the effectiveness of the concept can also be lower in certain cases that depend mainly on the operator. Full article

(This article belongs to the Special Issue Innovative and Intelligent Actuation for Heavy-Duty Applications)

Open AccessArticle

5G-Based Industrial Wireless Controller: Protocol Adaptation, Prototype Development, and Experimental Evaluation

and

Actuators 2023, 12(2), 49; https://doi.org/10.3390/act12020049 - 21 Jan 2023

Abstract

As a promising industrial wireless network technology, 5G URLLC is playing a key role in industrial control systems which employ different kinds of industrial control protocols. This leaves a significant challenge in how to adapt 5G URLLC with existing industrial control protocols and develop novel industrial wireless controllers. Motivated by this, this paper investigates the protocol adaptation and experimental evaluations for the development of a 5G-based industrial wireless controller prototype. Specifically, using the globally used industrial protocol Modbus as an example, we first deeply analyze the characteristics of the data packet format and the communication time sequence of Modbus RTU, Modbus TCP, and 5G protocols. Then, we propose a protocol resolution and conversion scheme for the protocol adaptation between Modbus RTU/Modbus TCP and 5G. Furthermore, we develop a wireless programmable logic controller (PLC) prototype system based on 5G. To evaluate the protocol adaptation scheme and the developed prototype, we perform extensive experiments to test the reliability and latency. The results demonstrate that the latency of the protocol adaptation scheme is smaller than that of protocol transparent transmission without resolution and conversion, while the reliability loss is not large. Moreover, the speed and reliability for the protocol adaptation between Modbus TCP and 5G are better than those between Modbus RTU and 5G. Full article

(This article belongs to the Section Control Systems)

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Open AccessArticle

Experimental Study and Simulation of Pull-In Behavior in Hybrid Levitation Microactuator for Square-Shaped Proof Masses

and

Actuators 2023, 12(2), 48; https://doi.org/10.3390/act12020048 - 20 Jan 2023

Abstract

This paper presents the results of a comprehensive study of the pull-in phenomenon in the hybrid levitation microactuator (HLMA), in which square-shaped proof masses (PMs) of different sizes, namely, length sides of 2.8 and 3.2 mm and thicknesses of 25 and 10 μm were electromagnetically levitated. The pull-in actuation of the square-shaped PMs was performed by the electrostatic force generated by the set of energized electrodes and acting on the bottom surface of the PMs along the vertical direction. The pull-in parameters, such as pull-in displacements and the corresponding applied pull-in voltages, were measured with the developed setup. The experimental measurements showed that the pull-in actuation is nonlinearly dependent on the size and mass of the PMs and a levitation height. In particular, it was found that PMs levitated within a height range from 140 to 170 μm can be stably displaced within a range of 30 μm. The results of measurements were extensively simulated with the developed analytical model by means of the quasi-FEM method. The direct comparison of the results of simulation and measurements showed a very good agreement between the theory and experiments. Full article

(This article belongs to the Special Issue Conventional and Micromachined Electromagnetic Levitation Actuators)

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Open AccessArticle

Effect of the Magnetorheological Damper Dynamic Behaviour on the Rail Vehicle Comfort: Hardware-in-the-Loop Simulation

and

Actuators 2023, 12(2), 47; https://doi.org/10.3390/act12020047 - 19 Jan 2023

Abstract

Many publications show that the ride comfort of a railway vehicle can be significantly improved using a semi-active damping control of the lateral secondary dampers. However, the control efficiency depends on the selection of the control algorithm and the damper dynamic behaviour, i.e., its force rise response time, force drop response time and force dynamic range. This paper examines the influence of these parameters of a magnetorheological (MR) damper on the efficiency of S/A control for several control algorithms. One new algorithm has been designed. Hardware-in-the-loop simulation with a real magnetorheological damper has been used to get close to reality. A key finding of this paper is that the highest efficiency of algorithms is not achieved with a minimal damper response time. Furthermore, the force drop response time has been more important than the force rise response time. The Acceleration Driven Damper Linear (ADD-L) algorithm achieves the highest efficiency. A reduction in vibration of 34% was achieved. Full article

(This article belongs to the Special Issue 10th Anniversary of Actuators)

Open AccessReview

A Review of Cooperative Actuator and Sensor Systems Based on Dielectric Elastomer Transducers

Gianluca Rizzello

Actuators 2023, 12(2), 46; https://doi.org/10.3390/act12020046 - 18 Jan 2023

Abstract

This paper presents an overview of cooperative actuator and sensor systems based on dielectric elastomer (DE) transducers. A DE consists of a flexible capacitor made of a thin layer of soft dielectric material (e.g., acrylic, silicone) surrounded with a compliant electrode, which is able to work as an actuator or as a sensor. Features such as large deformation, high compliance, flexibility, energy efficiency, lightweight, self-sensing, and low cost make DE technology particularly attractive for the realization of mechatronic systems that are capable of performance not achievable with alternative technologies. If several DEs are arranged in an array-like configuration, new concepts of cooperative actuator/sensor systems can be enabled, in which novel applications and features are made possible by the synergistic operations among nearby elements. The goal of this paper is to review recent advances in the area of cooperative DE systems technology. After summarizing the basic operating principle of DE transducers, several applications of cooperative DE actuators and sensors from the recent literature are discussed, ranging from haptic interfaces and bio-inspired robots to micro-scale devices and tactile sensors. Finally, challenges and perspectives for the future development of cooperative DE systems are discussed. Full article

(This article belongs to the Special Issue Cooperative Microactuator Devices and Systems)

Open AccessArticle

Reduction in Airfoil Trailing-Edge Noise Using a Pulsed Laser as an Actuator

and

Actuators 2023, 12(1), 45; https://doi.org/10.3390/act12010045 - 16 Jan 2023

Abstract

Trailing-edge noise (TE noise) is an aeroacoustic sound radiated from an isolated airfoil in the specific ranges of low-speed flow. We used a pulsed laser as an actuator to reduce the TE noise without modifying the airfoil’s surface. The wind tunnel test was conducted to verify the capability of an Nd:YAG laser as the actuator. The laser beam was focused into the air just outside the velocity boundary layer on the lower side of an NACA0012 airfoil. The experimental result shows that the TE noise is suppressed for a certain period after beam irradiations. We then analyzed the physical mechanism of the noise reduction with the laser actuation by the implicit large eddy simulation (ILES), a high-fidelity numerical method for computational fluid dynamics (CFD). The numerical investigations indicate that the pulsed energy deposition changes the unstable velocity amplification mode of the boundary layer, the source of an acoustic feedback loop radiating the TE noise, to another mode that does not generate the TE noise. The sound wave attenuation is observed once the induced velocity fluctuations and consequently generated vortices sweep out the flow structure of the unstable mode. We also examined the effect of the laser irradiation zone’s shape by numerical simulations. The results show that the larger irradiation zone, which introduces the disturbances over a wider range in the span direction, is more effective in reducing the TE noise than the shorter focusing length with the same energies. Full article

(This article belongs to the Special Issue Flow Control Actuators and Their Diverse Fluid Dynamic Applications)

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Open AccessArticle

Design and Implementation of Permanent and Electromagnet Composite Vibration Isolation System Based on Negative Stiffness Theory

and

Actuators 2023, 12(1), 44; https://doi.org/10.3390/act12010044 - 16 Jan 2023

Abstract

In order to decrease the transmission of vibration and achieve the attenuation of the vibration magnitude of an isolated object, a new type of permanent and electromagnet composite vibration isolation system is designed based on negative stiffness theory. Firstly, according to the characteristic analysis, the design of a permanent and electromagnet hybrid actuator is accomplished; secondly, the vibration isolation system model is established, and the active control strategy based on the fuzzy PID algorithm is designed. Finally, a test platform is built to verify the vibration isolation effect. The results indicate that the developed permanent and electromagnet composite vibration isolation system renders the sharp attenuation of external vibration in multiple frequency bands. When the external vibration frequency is within the frequency range of 20 Hz to 100 Hz, the vibration attenuation is greater than 80%; when the external vibration frequency is within the frequency range of 100 Hz to 500 Hz, the vibration attenuation rate is greater than 90%. Full article

(This article belongs to the Special Issue Advanced Theory and Application of Magnetic Actuators)

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Open AccessArticle

Flow Control around NACA0015 Airfoil Using a Dielectric Barrier Discharge Plasma Actuator over a Wide Range of the Reynolds Number

and

Actuators 2023, 12(1), 43; https://doi.org/10.3390/act12010043 - 16 Jan 2023

Abstract

In this study, an experimental investigation of separation control using a dielectric barrier discharge plasma actuator was performed on an NACA0015 airfoil over a wide range of Reynolds numbers, angles of attack, and nondimensional burst frequencies. The range of the Reynolds number was [...] Read more.

^{5}

to 1.008 × 10

^{6}

. A plasma actuator was installed at the leading edge and driven by AC voltage. Burst mode (duty-cycle) actuation was applied, with the nondimensional burst frequency ranging between 0.1–30. The control authority was evaluated using the time-averaged distribution of the pressure coefficient

C p

and the calculated value of the lift coefficient

C_{l}

. The baseline flow fields were classified into three types: (1) leading-edge separation; (2) trailing-edge separation; and (3) the hysteresis between (1) and (2). The results of the actuated cases show that the control trends clearly depend on the differences in the separation conditions. In leading-edge separation, actuation with a burst frequency of approximately

F^{+} =

0.5 creates a wide negative pressure region on the suction-side surface, leading to an increase in the lift coefficient. In trailing-edge separation, several actuations alter the position of turbulent separation. Full article

(This article belongs to the Special Issue Dielectric Barrier Discharge Plasma Actuator for Active Flow Control)

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Open AccessEditorial

Acknowledgment to the Reviewers of Actuators in 2022

Actuators Editorial Office

Actuators 2023, 12(1), 42; https://doi.org/10.3390/act12010042 - 16 Jan 2023

Abstract

High-quality academic publishing is built on rigorous peer review [...] Full article

Open AccessArticle

Integrated Vehicle Controller for Path Tracking with Rollover Prevention of Autonomous Articulated Electric Vehicle Based on Model Predictive Control

Yonghwan Jeong

Actuators 2023, 12(1), 41; https://doi.org/10.3390/act12010041 - 12 Jan 2023

Abstract

This paper presents an integrated controller for an autonomous articulated electric vehicle (AAEV) for path tracking and rollover prevention. The AAEV is vulnerable to rollover due to the characteristics of the articulated frame steering (AFS) mechanism, which shows improved maneuverability and agility but not front wheel steering. In addition, the ratio between height and track width is high, so the AAEV is prone to rolling over. Therefore, the proposed controller was designed to achieve the two goals, following the reference path and managing the velocity to improve the safety of the AAEV. Vehicle behavior was modeled by a kinematic model with actuation delay. A local linearization was used to improve the accuracy of the vehicle model and reduce the computational load. Reference states of the position and heading were determined to follow the reference path and prevent the rollover. A model predictive control (MPC)-based reference state tracker was designed to optimize the articulation angle rate and longitudinal acceleration commands. The simulation study was conducted to evaluate the proposed algorithm with a comparison of the base algorithms. The reference path for the simulation was an S-shaped path with discontinuous curvature. Simulation results showed that the proposed algorithm reduces the path tracking error and load-transfer ratio. Full article

(This article belongs to the Special Issue Design, Control, and Optimization of Powertrain for New Energy Vehicles)

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Open AccessArticle

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

and

Actuators 2023, 12(1), 40; https://doi.org/10.3390/act12010040 - 12 Jan 2023

Abstract

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. Full article

(This article belongs to the Special Issue Linear Motors and Direct-Drive Technology)

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Open AccessArticle

A Gripper-like Exoskeleton Design for Robot Grasping Demonstration

and

Actuators 2023, 12(1), 39; https://doi.org/10.3390/act12010039 - 12 Jan 2023

Abstract

Learning from demonstration (LfD) is a practical method for transferring skill knowledge from a human demonstrator to a robot. Several studies have shown the effectiveness of LfD in robotic grasping tasks to improve the success rate of grasping and to accelerate the development of new robotic grasping tasks. A well-designed demonstration device can effectively represent human grasping motion to transfer grasping skills to robots. In this paper, an improved gripper-like exoskeleton with a data collection system is proposed. First, we present the mechatronic details of the exoskeleton and its motion-tracking system, considering the manipulation flexibility and data acquisition requirements. We then present the capabilities of the device and its data collection system, which collects the position, pose and displacement of the gripper on the exoskeleton. The collected data is further processed by the data acquisition and processing software. Next, we describe the principles of Gaussian mixture model (GMM) and Gaussian mixture regression (GMR) in robot skill learning, which are used to transfer the raw data from demonstrations to robot motions. In the experiment, an optimized trajectory was learned from multiple demonstrations and reproduced on a robot. The results show that the GMR complemented with GMM is able to learn a smooth trajectory from demonstration trajectories with noise. Full article

(This article belongs to the Special Issue Advanced Technologies and Applications in Robotics)

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Open AccessArticle

Target Tracking of Snake Robot with Double-Sine Serpentine Gait Based on Adaptive Sliding Mode Control

and

Actuators 2023, 12(1), 38; https://doi.org/10.3390/act12010038 - 10 Jan 2023

Abstract

This paper studies the target tracking control strategy of a snake robot and proposes an adaptive sliding mode control method. The strategy ensures the robot follows the target path by controlling the joint angle through feedback, pushing the robot to reach the target position through gait function. In order to achieve target tracking, a kinematic model of a snake robot was first established in this paper. Then, we used double-sine serpentine gait to solve the problem of low steering efficiency caused by regular serpentine gait, and we explored the relationship between control parameters and robot steering. On the basis of gait, in order to further improve the efficiency of target tracking for the snake robot, an adaptive sliding mode control method, based on a new sliding mode reaching law, was proposed. Finally, the effectiveness and practicability of the proposed strategy was demonstrated by comparative analysis and simulation experiments. Full article

(This article belongs to the Special Issue Applications of Intelligent Control in Actuators Systems)

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Open AccessArticle

Electromechanical Coupling Dynamic and Vibration Control of Robotic Grinding System for Thin-Walled Workpiece

Yufei Liu

Dong Tang

and

Jinyong Ju

Actuators 2023, 12(1), 37; https://doi.org/10.3390/act12010037 - 10 Jan 2023

Abstract

The robotic grinding system for a thin-walled workpiece is a multi-dimensional coupling system composed of a robot, a grinding spindle and the thin-walled workpiece. In the grinding process, a dynamic coupling effect is generated, while the thin-walled workpiece stimulates elastic vibration; the grinding spindle, as an electromechanical coupling actuator, is sensitive to the elastic vibration in the form of load fluctuations. It is necessary to investigate the electromechanical coupling dynamic characteristics under the vibration coupling of the thin-walled workpiece as well as the vibration control of the robotic grinding system. Firstly, considering the dynamic coupling effect between the grinding spindle and thin-walled workpiece, a dynamic model of the grinding spindle and thin-walled workpiece coupling system is established. Secondly, based on this established coupling dynamic model, the vibration characteristics of the thin-walled workpiece and the electromechanical coupling dynamic characteristics of the grinding spindle are investigated. Finally, a speed adaptive control system for the grinding spindle is designed based on a fuzzy PI controller, which can achieve a stable speed for the grinding spindle under vibration coupling and has a certain suppression effect on the elastic vibration of the thin-walled workpiece at the same time. Full article

(This article belongs to the Special Issue Modeling, Optimization and Control of Robotic Systems)

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Open AccessArticle

Variational Reduced-Order Modeling of Thermomechanical Shape Memory Alloy Based Cooperative Bistable Microactuators

Muhammad Babar Shamim

Marian Hörsting

and

Stephan Wulfinghoff

Actuators 2023, 12(1), 36; https://doi.org/10.3390/act12010036 - 10 Jan 2023

Abstract

This article presents the formulation and application of a reduced-order thermomechanical finite strain shape memory alloy (SMA)-based microactuator model for switching devices under thermal loading by Joule heating. The formulation is cast in the generalized standard material framework with an extension for thermomechanics. The proper orthogonal decomposition (POD) is utilized for capturing a reduced basis from a precomputed finite element method (FEM) full-scale model. The modal coefficients are computed by optimization of the underlying incremental thermomechanical potential, and the weak form for the mechanical and thermal problem is formulated in reduced-order format. The reduced-order model (ROM) is compared with the FEM model, and the exemplary mean absolute percentage errors for the displacement and temperature are

0.973 %

and

0.089 %

, respectively, with a speedup factor of

9.56

for a single SMA-based actuator. The ROM presented is tested for single and cooperative beam-like actuators. Furthermore, cross-coupling effects and the bistability phenomenon of the microactuators are investigated. Full article

(This article belongs to the Special Issue Cooperative Microactuator Devices and Systems)

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