Special Issue "Actuators in Robotic Control"

A special issue of Actuators (ISSN 2076-0825).

Deadline for manuscript submissions: closed (31 August 2021).

Special Issue Editor

Prof. Dr. Chih Jer Lin
E-Mail Website
Guest Editor
Graduate Institute of Automation Technology, National Taipei University of Technology, 1, Sec. 3, Zhongxiao E. Rd., Taipei 10608, Taiwan
Interests: numerical simulation; nonlinear control; mechatronics; precision motion control; system identification; sliding-mode control; robotics; evolutionary algorithms
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Industrial robotic applications are becoming more and more common in manufacturing companies, where automation technologies have led the progress so far. Robotics is expected to have the potential to bring disruptive innovations in the coming decades and not only in the industrial environment. At home or in a hospital, assistant robotic systems are not only supposed to substitute humans, but will also have to collaborate and interact with them. Therefore, they require different technology from the one currently in use; for example, soft robotics is a new field in robotics which is being used to deal with the demand. To make all of the components in the robot soft and flexible, the actuators should provide their movements in limited spaces and change gaits fairly easily.

Actuators are essential devices in these robotics and automation systems; in particular, humanoid/legged robots have different needs compared to industrial robots. To meet these different needs, many researchers have developed new types of actuator. The future of robotics will rely heavily on actuators with force/torque control. For robotic systems, how to manipulate fragile items as humans can do is a big and challenging task. Electric actuators are suitable for this purpose, but they are not yet optimized. As a matter of fact, robotic arms and legs should reproduce the ability of human arms and legs on several levels. However, human muscles in limbs can also store energy and have a sort of internal elasticity. To reproduce the behaviors in human muscles, one or more elastic elements are inserted into electric actuators. The implementations of soft actuators exhibit high mechanical complexity and their size, weight, and cost prevent their widespread use. As a result, their application to multi-degree-of-freedom robotic machines still remains an open issue and a challenging task.

Prof. Dr. Chih Jer Lin
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Actuators is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Variable impedance actuators
  • soft actuators
  • elastic actuators
  • electric actuators
  • pneumatic artificial muscles
  • force/torque control
  • sofe robotics
  • mobile robots
  • humanoid robotics
  • wearable robotic system
  • assitant robotics
  • upper limb exoskeletons
  • lower limb exoskeletons

Published Papers (9 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Article
Adaptive Control of Chaotic Signals: Investigated by Simulation Software and Real Electronic Circuits
Actuators 2021, 10(11), 284; https://doi.org/10.3390/act10110284 - 25 Oct 2021
Viewed by 277
Abstract
Chaotic behavior is complicated, sensitive, and has the feature of great variety, which are the most potential signals to be applied in data encryption, secure communication, medical information protection, etc. As a consequence, in this paper, we try to propose three different ways [...] Read more.
Chaotic behavior is complicated, sensitive, and has the feature of great variety, which are the most potential signals to be applied in data encryption, secure communication, medical information protection, etc. As a consequence, in this paper, we try to propose three different ways to show our data generating results step by step, which means it can be proved effectively and used in practice: (1) Chaotic solutions simulated by MATLAB, (2) chaotic motion drawn via electronic circuits software Multisim, and (3) chaotic signal implemented on real electronic circuits with breadboard. In advance, following the same design principal, the adaptive chaotic signal is also designed and presented in the end of this article for further study, which provides a more flexible and variable chaotic signal to enhance the encryption effectiveness. The experimental results are extremely close to the two simulation results and can definitely be technically transferred to real encryption application. Full article
(This article belongs to the Special Issue Actuators in Robotic Control)
Show Figures

Figure 1

Article
Investigation of Hysteresis Effect in Torque Performance for a Magnetorheological Brake in Adaptive Knee Orthosis
Actuators 2021, 10(10), 271; https://doi.org/10.3390/act10100271 - 15 Oct 2021
Viewed by 468
Abstract
Semi-active knee orthosis (SAKO) is a kind of wearable lower-limb exoskeleton that uses actuators to support the regular biomechanical functions. It is much better than conventional knee orthosis (CKO) devices because of its high torque to volume ratio (TVR) and low mass. Magnetorheological [...] Read more.
Semi-active knee orthosis (SAKO) is a kind of wearable lower-limb exoskeleton that uses actuators to support the regular biomechanical functions. It is much better than conventional knee orthosis (CKO) devices because of its high torque to volume ratio (TVR) and low mass. Magnetorheological (MR) brake is one of the smart actuators that can be used as an active resistance device in SAKO. It has advantages of fast response, low power consumption, and low vibration operation. This smart brake also has wide applications in the robotic and automotive industries. However, the electromagnetic setup in MR brakes has a hysteresis problem. This paper aims to turn this hysteresis problem into an advantage to save the power consumption of MR brake. Since the SAKO needs precise torque control, this research studied the hysteresis effect on the torque performance of MR brake. A less energy-consuming PWM actuation signal is proposed to activate the MR brake. The effects of frequency and duty cycle of PWM actuation signal on MR brake performance are also investigated. The electromagnetic (EM) and mechanical models of the MR brake were developed to simulate performance. Initial validation of these models is done by simulating the MR brake model with the DC actuation signal in finite element analysis software. For the final validation, the model simulation results are compared with experimental results. The factors affecting the steady torque and the response time of the MR brake are studied to find the optimal frequency and duty cycle for the applied PWM signal. This study revealed that the proposed new PWM actuation signal with a 5 kHz frequency and 60% duty cycle can power the MR brake to maintain steady torque. By turning hysteresis into an advantage, it saves 40% power consumption of MR brake compared to DC signal. Full article
(This article belongs to the Special Issue Actuators in Robotic Control)
Show Figures

Figure 1

Article
Port-Hamiltonian Modeling and IDA-PBC Control of an IPMC-Actuated Flexible Beam
Actuators 2021, 10(9), 236; https://doi.org/10.3390/act10090236 - 14 Sep 2021
Cited by 1 | Viewed by 622
Abstract
In this paper, the infinite-dimensional port-Hamiltonian modelling and control problem of a flexible beam actuated using ionic polymer metal composite (IPMC) actuators is investigated. The port-Hamiltonian framework is used to propose an interconnected control model of the mechanical flexible beam and the IPMC [...] Read more.
In this paper, the infinite-dimensional port-Hamiltonian modelling and control problem of a flexible beam actuated using ionic polymer metal composite (IPMC) actuators is investigated. The port-Hamiltonian framework is used to propose an interconnected control model of the mechanical flexible beam and the IPMC actuator. The mechanical flexible dynamic is modelled as a Timoshenko beam, and the electric dynamics of the IPMCs are considered in the model. Furthermore, a passivity-based control-strategy is used to obtain the desired configuration of the proposed interconnected system, and the closed-loop stability is analyzed using the early lumped approach. Lastly, numerical simulations and experimental results are presented to validate the proposed model and the effectiveness of the proposed control law. Full article
(This article belongs to the Special Issue Actuators in Robotic Control)
Show Figures

Figure 1

Article
Design and Implementation of a Robotic Hip Exoskeleton for Gait Rehabilitation
Actuators 2021, 10(9), 212; https://doi.org/10.3390/act10090212 - 29 Aug 2021
Cited by 1 | Viewed by 522
Abstract
In this paper, a four degrees-of-freedom robotic hip exoskeleton was proposed for gait rehabilitation. The robotic hip exoskeleton was designed with active flexion/extension and passive abduction/adduction at each hip joint to comply with the movement of the thigh. Due to each user’s different [...] Read more.
In this paper, a four degrees-of-freedom robotic hip exoskeleton was proposed for gait rehabilitation. The robotic hip exoskeleton was designed with active flexion/extension and passive abduction/adduction at each hip joint to comply with the movement of the thigh. Due to each user’s different lower limbs characteristics and unknown torques at hip joints, model-free linear extended state observer (LESO)-based controllers were proposed for rehabilitation gait control. The prototypes of the robotic hip exoskeleton and controller designs were validated and compared through walking and ascending rehabilitation experiments. Additionally, a motion captured system and EMG signals were used to investigate the walking assistance of the robotic hip exoskeleton. Full article
(This article belongs to the Special Issue Actuators in Robotic Control)
Show Figures

Figure 1

Article
MCI Detection Using Kernel Eigen-Relative-Power Features of EEG Signals
Actuators 2021, 10(7), 152; https://doi.org/10.3390/act10070152 - 04 Jul 2021
Viewed by 834
Abstract
Classification between individuals with mild cognitive impairment (MCI) and healthy controls (HC) based on electroencephalography (EEG) has been considered a challenging task to be addressed for the purpose of its early detection. In this study, we proposed a novel EEG feature, the kernel [...] Read more.
Classification between individuals with mild cognitive impairment (MCI) and healthy controls (HC) based on electroencephalography (EEG) has been considered a challenging task to be addressed for the purpose of its early detection. In this study, we proposed a novel EEG feature, the kernel eigen-relative-power (KERP) feature, for achieving high classification accuracy of MCI versus HC. First, we introduced the relative powers (RPs) between pairs of electrodes across 21 different subbands of 2-Hz width as the features, which have not yet been used in previous MCI-HC classification studies. Next, the Fisher’s class separability criterion was applied to determine the best electrode pairs (five electrodes) as well as the frequency subbands for extracting the most sensitive RP features. The kernel principal component analysis (kernel PCA) algorithm was further performed to extract a few more discriminating nonlinear principal components from the optimal RPs, and these components form a KERP feature vector. Results carried out on 51 participants (24 MCI and 27 HC) show that the newly introduced subband RP feature showed superior classification performance to commonly used spectral power features, including the band power, single-electrode relative power, and also the RP based on the conventional frequency bands. A high leave-one-participant-out cross-validation (LOPO-CV) classification accuracy 86.27% was achieved by the RP feature, using a simple linear discriminant analysis (LDA) classifier. Moreover, with the same classifier, the proposed KERP further improved the accuracy to 88.24%. Finally, cascading the KERP feature to a nonlinear classifier, the support vector machine (SVM), yields a high MCI-HC classification accuracy of 90.20% (sensitivity = 87.50% and specificity = 92.59%). The proposed method demonstrated a high accuracy and a high usability (only five electrodes are required), and therefore, has great potential to further develop an EEG-based computer-aided diagnosis system that can be applied for the early detection of MCI. Full article
(This article belongs to the Special Issue Actuators in Robotic Control)
Show Figures

Figure 1

Article
Develop Real-Time Robot Control Architecture Using Robot Operating System and EtherCAT
Actuators 2021, 10(7), 141; https://doi.org/10.3390/act10070141 - 24 Jun 2021
Viewed by 851
Abstract
This paper presents the potential of combining ROS (Robot Operating System), its state-of-art software, and EtherCAT technologies to design real-time robot control architecture for human–robot collaboration. For this, the advantages of an ROS framework here are it is easy to integrate sensors for [...] Read more.
This paper presents the potential of combining ROS (Robot Operating System), its state-of-art software, and EtherCAT technologies to design real-time robot control architecture for human–robot collaboration. For this, the advantages of an ROS framework here are it is easy to integrate sensors for recognizing human commands and the well-developed communication protocols for data transfer between nodes. We propose a shared memory mechanism to improve the communication between non-real-time ROS nodes and real-time robot control tasks in motion kernel, which is implemented in the ARM development board with a real-time operating system. The jerk-limited trajectory generation approach is implemented in the motion kernel to obtain a fine interpolation of ROS MoveIt planned robot path to motor. EtherCAT technologies with precise multi-axis synchronization performance are used to exchange real-time I/O data between motion kernel and servo drive system. The experimental results show the proposed architecture using ROS and EtherCAT in hard real-time environment is feasible for robot control application. With the proposed architecture, a user can efficiently send commands to a robot to complete tasks or read information from the robot to make decisions, which is helpful to reach the purpose of human–robot collaboration in the future. Full article
(This article belongs to the Special Issue Actuators in Robotic Control)
Show Figures

Figure 1

Article
A Robust Noise-Free Linear Control Design for Robot Manipulator with Uncertain System Parameters
Actuators 2021, 10(6), 121; https://doi.org/10.3390/act10060121 - 05 Jun 2021
Cited by 3 | Viewed by 799
Abstract
In robot control, the sliding mode control is known for its robustness against external disturbances and system uncertainties. However, it has the disadvantage of control chattering, which can damage the actuator and degrade system performance. With a new stability proof, this paper presents [...] Read more.
In robot control, the sliding mode control is known for its robustness against external disturbances and system uncertainties. However, it has the disadvantage of control chattering, which can damage the actuator and degrade system performance. With a new stability proof, this paper presents an alternative simple linear feedback control that can cope with large system uncertainties and suppress large external disturbances, doing so as effectively as sliding mode control does. The advantage of using linear control is that the control law is simple and control chattering can be avoided. Moreover, a noise-free control scheme is proposed as an improvement of the feedback control; the modified design preserves the advantages of linear control and generates a chattering-free control signal even in a noisy environment. Full article
(This article belongs to the Special Issue Actuators in Robotic Control)
Show Figures

Figure 1

Article
Output Feedback Tracking Sliding Mode Control for Systems with State- and Input-Dependent Disturbances
Actuators 2021, 10(6), 117; https://doi.org/10.3390/act10060117 - 31 May 2021
Cited by 1 | Viewed by 946
Abstract
In this paper, output feedback tracking sliding mode control was considered for uncertain multivariable linear systems. The uncertainties included external disturbance, the system state, and control input. A new property of the loop transfer recovery (LTR) observer was first established: the state estimation [...] Read more.
In this paper, output feedback tracking sliding mode control was considered for uncertain multivariable linear systems. The uncertainties included external disturbance, the system state, and control input. A new property of the loop transfer recovery (LTR) observer was first established: the state estimation error of the LTR observer can be made arbitrarily small with respect to state- and input-dependent system uncertainties. Observer-based output feedback tracking sliding mode control using the LTR observer is presented. The proposed sliding mode control approach can maintain the boundedness of the system state and drive the system outputs arbitrarily close to the desired reference outputs; the degree of closeness was determined by a design parameter in the LTR observer. In the proposed approach, the most general and simple observer-based output feedback control formulation was used to achieve global tracking. Simulations with a two-degree-of-freedom (DOF) robotic manipulator application illustrated the claimed properties, and a peaking and chattering reduction technique was demonstrated to protect the actuator. Full article
(This article belongs to the Special Issue Actuators in Robotic Control)
Show Figures

Figure 1

Article
Tracking Control of Pneumatic Artificial Muscle-Activated Robot Arm Based on Sliding-Mode Control
Actuators 2021, 10(3), 66; https://doi.org/10.3390/act10030066 - 22 Mar 2021
Cited by 3 | Viewed by 1031
Abstract
This study discusses a circular trajectory tracking function through a proposed pneumatic artificial muscle (PAM)-actuated robot manipulator. First, a dynamic model between a robot arm and a PAM cylinder is introduced. Then the parameters thereof are identified through a genetic algorithm (GA). Finally, [...] Read more.
This study discusses a circular trajectory tracking function through a proposed pneumatic artificial muscle (PAM)-actuated robot manipulator. First, a dynamic model between a robot arm and a PAM cylinder is introduced. Then the parameters thereof are identified through a genetic algorithm (GA). Finally, PID is used along with a high-order sliding-mode feedback controller to perform circular trajectory tracking. As the experimental results show, the parameters of sampling time and moment of inertia are set to accomplish the trajectory tracking task in this study. In addition, the maximum error between the objective locus and the following locus was 11.3035 mm when applying theta-axis control to the circular trajectory of the robot arm with zero load or lower load. In an experiment of controller comparison, the results demonstrate that a high-order sliding-mode feedback controller is more robust in resisting external interference and the uncertainty of modeling, making the robot arm have good performance when tracking. Full article
(This article belongs to the Special Issue Actuators in Robotic Control)
Show Figures

Figure 1

Back to TopTop