Research

17 pages, 53761 KiB

Open AccessArticle

Fabrication and Characterization of Pneumatic Unit Cell Actuators

by Krishna Dheeraj Kommuri, Femke E. Van Beek and Irene A. Kuling

Actuators 2024, 13(2), 45; https://doi.org/10.3390/act13020045 - 23 Jan 2024

Viewed by 1254

In the realm of virtual and augmented reality (VR/AR) and teleoperation applications, haptic feedback plays a role in enhancing task performance. One of the main goals of this study is to simplify haptic device hardware while improving its capacity to provide various stimuli [...] Read more.

In the realm of virtual and augmented reality (VR/AR) and teleoperation applications, haptic feedback plays a role in enhancing task performance. One of the main goals of this study is to simplify haptic device hardware while improving its capacity to provide various stimuli at different intensities. In response to these challenges, this research introduces the Pneumatic Unit Cell (PUC), a soft pneumatically driven device—a hollow silicone cylinder with the ability to provide both static-pressure and vibrotactile feedback. Furthermore, the Pneumatic Unit Cell’s design simplicity has the potential for scalability, modularity, and the flexibility to mount the device on any part of the human body. The focus of the current paper is to study PUCs as actuators and lay the foundation for future perceptual studies. The characterization studies encompass the fabrication and verification of the fabrication accuracy through dimensional measurements, characterizing PUCs under static-pressure conditions (measuring the free deflection and blocking force) and frequency conditions (measuring the free deflection). In the static-pressure conditions, we applied pressures ranging from 0 to 40 kPa to measure the free deflection and from 0 to 30 kPa to measure the blocking force. In the frequency conditions, we applied pressures of 10, 20, and 30 kPa with inflation/deflation rates varying between 0.5 Hz and 100 Hz. The measurements of free deflection under static-pressure conditions revealed that 0.9 mm and 1.2 mm PUCs exhibit a linear increase in free deflection with an increase in inflation pressure. The results of free-deflection measurements under the frequency conditions indicate a direct relationship between the free-deflection magnitude and applied pressure. The results also demonstrate an inverse relationship to the frequency of inflation/deflation. The characterization results demonstrate a broad range of free deflection observed under both static-pressure and frequency conditions, encouraging the potential application of Pneumatic Unit Cell actuators as haptic devices. Full article

(This article belongs to the Special Issue Advanced Actuation, Intelligent Sensor and Precise Manipulation Technology in Human–Robot Interaction)

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16 pages, 1217 KiB

Open AccessArticle

Observer-Based Nonlinear Proportional–Integral–Integral Speed Control for Servo Drive Applications via Order Reduction Technique

by Yonghun Kim, Hyunho Ye, Sun Lim and Seok-Kyoon Kim

Actuators 2024, 13(1), 2; https://doi.org/10.3390/act13010002 - 21 Dec 2023

Viewed by 1058

Abstract

This study designs an advanced single-loop output feedback system for speed servo drive applications, in which a simple proportional–integral–integral (PII) controller equipped with nonlinear feedback and feed-forward gains is formed. The resultant feedback system shows the desired critically damped performance for wide-operating regions [...] Read more.

This study designs an advanced single-loop output feedback system for speed servo drive applications, in which a simple proportional–integral–integral (PII) controller equipped with nonlinear feedback and feed-forward gains is formed. The resultant feedback system shows the desired critically damped performance for wide-operating regions by actively handling the system parameter and load uncertainties. There are three contributions: first, the third-order observer estimates, independent from the system model, where the speed and acceleration are obtained using the position measurement with the order reduction property; second, the observer-based PII controller is compensated by active damping with a nonlinearly structured feedback and feed-forward gains; and, third, a guarantee is achieved on the desired critically damped performance through a closed-loop analysis. A hardware testbed that adopts a 500 W brushless DC motor is used to experimentally demonstrate performance improvements over certain constant torque regions under various scenarios. Full article

(This article belongs to the Special Issue Advanced Actuation, Intelligent Sensor and Precise Manipulation Technology in Human–Robot Interaction)

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17 pages, 5523 KiB

Open AccessArticle

Antagonistic Magneto-Rheological Actuators with Inherent Output Boundedness: An Ideal Solution for High-Performance and Human-Safe Actuation

by Mehrdad R. Kermani, Sergey Pisetskiy, Ilia Polushin and Zi-Qi Yang

Actuators 2023, 12(9), 351; https://doi.org/10.3390/act12090351 - 31 Aug 2023

Viewed by 1069

Abstract

This paper studies the working principles of antagonistic magneto-rheological (MR) actuators, i.e., a combination of an electric motor and a pair of MR clutches in an antagonistic configuration, for compliant actuation in robotics. The study focuses on the unique boundedness property exhibited by [...] Read more.

This paper studies the working principles of antagonistic magneto-rheological (MR) actuators, i.e., a combination of an electric motor and a pair of MR clutches in an antagonistic configuration, for compliant actuation in robotics. The study focuses on the unique boundedness property exhibited by MR actuators, which limits the output torques delivered to the load, independent of the received input torque and/or control commands. This inherent property is of significant importance for ensuring human safety in human–robot interaction applications. Through a comprehensive analysis, we provide analytical proof of the inherent output boundedness of antagonistic MR actuators and validate our findings through experimental results. Our research demonstrates that these actuators are well-suited for safe operations in robotic applications, eliminating the need for additional sensor measurements or complex control strategies. This promising capability enables the avoidance of trade-offs between actuator performance, complexity, and cost. The insights gained from this study contribute to advancing compliant actuation technology, paving the way for high-performance and human-safe robotic systems. Full article

(This article belongs to the Special Issue Advanced Actuation, Intelligent Sensor and Precise Manipulation Technology in Human–Robot Interaction)

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17 pages, 5342 KiB

Open AccessArticle

Design and Analysis of a Novel Actuator with a Double-Roller Gear Drive

by Xuan Li, Yang Li, Weilong Niu and Ran Guo

Actuators 2023, 12(7), 292; https://doi.org/10.3390/act12070292 - 18 Jul 2023

Viewed by 1602

Abstract

In recent years, with the development of robot transmission technology, the market demand for high-performance actuators, which can be applied to lower limb exoskeleton assist robots, is increasing. These robots help achieve human–robot interaction through rigid and flexible coupling, and they can ensure [...] Read more.

In recent years, with the development of robot transmission technology, the market demand for high-performance actuators, which can be applied to lower limb exoskeleton assist robots, is increasing. These robots help achieve human–robot interaction through rigid and flexible coupling, and they can ensure the flexibility of the elderly or patients in daily walking and rehabilitation training. A novel actuator with a double-roller gear drive structure is proposed with high bearing capability and high transmission efficiency due to multi-tooth rolling contact with small tooth difference such that friction is greatly reduced in the transmission process compared to what occurs in involute planetary transmission. The bearing capacity of the tooth surface was analyzed by using the loaded contact analysis method. Finally, a prototype was manufactured with the 3D printer, and the maximum output torque of the developed actuator was tested with an experimental setup. The results show that this novel actuator, with its double-roller gear drive, has huge potential for use in the hip joint of an exoskeleton robot. Full article

(This article belongs to the Special Issue Advanced Actuation, Intelligent Sensor and Precise Manipulation Technology in Human–Robot Interaction)

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15 pages, 16694 KiB

Open AccessArticle

A Novel High-Voltage-Cable Stripping Robot

by Jun Zhong, Wenxu Ai, Zhichao Wang, Shaoguang Hu and Hongshuang Zhang

Actuators 2023, 12(5), 201; https://doi.org/10.3390/act12050201 - 12 May 2023

Viewed by 1343

Abstract

One of the primary duties in the regular maintenance of electrical distribution networks is the cable stripping operation. In this paper, a unique robot is proposed to overcome drawbacks of the conventional manual operation of cable stripping, such as poor efficiency, low safety, [...] Read more.

One of the primary duties in the regular maintenance of electrical distribution networks is the cable stripping operation. In this paper, a unique robot is proposed to overcome drawbacks of the conventional manual operation of cable stripping, such as poor efficiency, low safety, and high labor intensity. This innovative cable-stripping robot is made up of a rotating mechanism, a cable gripping component, and a cutter feeding mechanism that can be adjusted depending on the working environment and workload. The robot’s motors, sensors, main control chip, and wireless communication modules are all carefully selected. A carefully designed cascade controller is created for the robot in an effort to lessen damage to the aluminum core. While the outside location loop uses the PID algorithm, the inner speed control loop uses fuzzy PID. The robot can successfully accomplish cable stripping work and demonstrates its potential to reduce labor intensity. Cable stripping experiments are conducted to validate the effect of the robot and its controller. Full article

(This article belongs to the Special Issue Advanced Actuation, Intelligent Sensor and Precise Manipulation Technology in Human–Robot Interaction)

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14 pages, 4976 KiB

Open AccessArticle

Error Analysis of a Coordinate Measuring Machine with a 6-DOF Industrial Robot Holding the Probe

by Yaowei Sun, Lei Lu, Fengzhou Wu, Songlu Xiao, Junjie Sha and Lei Zhang

Actuators 2023, 12(4), 173; https://doi.org/10.3390/act12040173 - 16 Apr 2023

Cited by 1 | Viewed by 2168

Abstract

A complex surface measurement is important for quality control and manufacturing processes. Articulated arm coordinate measuring machines (AACMMs) are widely used in measuring the complex surface. However, the AACMMs that are currently used always require manual operation, which reduces efficiency and introduces operator [...] Read more.

A complex surface measurement is important for quality control and manufacturing processes. Articulated arm coordinate measuring machines (AACMMs) are widely used in measuring the complex surface. However, the AACMMs that are currently used always require manual operation, which reduces efficiency and introduces operator errors. This study presents a measuring device with a 6−DOF industrial robot holding a contact probe, which realizes the automation measurement of a complex surface and eliminates operator errors compared with the traditional measurement process of an AACMM. In order to explore the source of the measuring errors of the device, the influence of three measurement parameters (approaching velocity, contact angle, and measurement position) on the measurement error of the device is analyzed in this paper. A calibration ball measurement experiment is conducted for each parameter. The results show that the optimal approaching velocity of the measuring device is around 2 mm/s, the probe should be as perpendicular as possible to the surface being measured during the measurement, and the maximum measurement error at different positions is 0.1979 mm, with a maximum repeatability error of 0.0219 mm. This study will help improve the automation measuring errors of the AACMM by utilizing an industrial robot to hold the probe, pushing for a wider application of the AACMM. Full article

(This article belongs to the Special Issue Advanced Actuation, Intelligent Sensor and Precise Manipulation Technology in Human–Robot Interaction)

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20 pages, 6356 KiB

Open AccessArticle

A Compact Electromagnetic Dual Actuation Positioning System with a 10 mm Range and Nanometer Resolution

by Bimal Jeet Goteea, Qianjun Zhang and Wei Dong

Actuators 2023, 12(3), 132; https://doi.org/10.3390/act12030132 - 21 Mar 2023

Cited by 1 | Viewed by 1376

Abstract

In this manuscript, a compact electromagnetic dual actuation positioning system (CEDAPS) based on the Lorentz force principle that features a 10 mm range and nanometer-scale resolution with flexure guides is presented. Firstly, the stiffness of the flexure mechanism is modelled. Secondly, based on [...] Read more.

In this manuscript, a compact electromagnetic dual actuation positioning system (CEDAPS) based on the Lorentz force principle that features a 10 mm range and nanometer-scale resolution with flexure guides is presented. Firstly, the stiffness of the flexure mechanism is modelled. Secondly, based on it, the primary coil is designed, and from its performance, a suitable secondary coil is made to compensate for the deficiency of the primary actuation subsystem. The characteristics of the forces generated by these coils are also evaluated by an electromagnetic FEA simulation. Thirdly, a control scheme is presented that combines the performances of these two actuators, and finally, a prototype is fabricated to evaluate the performance. The results show a 10 nm resolution for a 10 mm (±5 mm) stroke with low sub-micron sinusoidal tracking errors and nanometer accuracy for step tracking under the proposed control scheme. The thermal properties of the system are also presented. Full article

(This article belongs to the Special Issue Advanced Actuation, Intelligent Sensor and Precise Manipulation Technology in Human–Robot Interaction)

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11 pages, 789 KiB

Open AccessArticle

Design of High Precision Interval Observer for Robot System

by Shuang Duan, Zhida Shao, Xinyao Chen, Xuan Li, Yiyang Chen and Haidong He

Actuators 2023, 12(3), 116; https://doi.org/10.3390/act12030116 - 09 Mar 2023

Cited by 1 | Viewed by 1315

Abstract

In order to solve the problem of parameter uncertainty and unknown external interference of wheeled mobile robots (WMR) in a complex environment, the design of a high-precision interval observer for the robot system is proposed. In this paper, the kinematics and dynamics model [...] Read more.

In order to solve the problem of parameter uncertainty and unknown external interference of wheeled mobile robots (WMR) in a complex environment, the design of a high-precision interval observer for the robot system is proposed. In this paper, the kinematics and dynamics model of a wheeled mobile robot is derived first, and then the control strategy of high-precision interval observer is introduced to estimate and compensate for the unknown state and uncertainty of the system in real-time, which realizes the robustness of the system to disturbance and high adaptability to the environment. The stability of the system is proved by Lyapunov’s theory. The experimental results show that other methods based on coordinate transformation, though the design conditions are relaxed to a certain extent, bring some conservatism. The method proposed in this paper can obtain more accurate interval estimation, so the performance of the method proposed in this paper is better. In conclusion, the control method proposed in this paper can make the mobile robot system have good tracking control performance and strong robustness. Full article

(This article belongs to the Special Issue Advanced Actuation, Intelligent Sensor and Precise Manipulation Technology in Human–Robot Interaction)

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18 pages, 7173 KiB

Open AccessArticle

Microforce Sensing and Flexible Assembly Method for Key Parts of ICF Microtargets

by Tao Chen, Kejian Ni, Minglu Zhu and Lining Sun

Actuators 2023, 12(1), 1; https://doi.org/10.3390/act12010001 - 20 Dec 2022

Viewed by 1144

Abstract

Microassembly is one of the key techniques in various advanced industrial applications. Meanwhile, high success rates for axial hole assembly of thin-walled deep-cavity-type items remain a challenging issue. Hence, the flexible assembly approach of thin-walled deep-cavity parts is investigated in this study using [...] Read more.

Microassembly is one of the key techniques in various advanced industrial applications. Meanwhile, high success rates for axial hole assembly of thin-walled deep-cavity-type items remain a challenging issue. Hence, the flexible assembly approach of thin-walled deep-cavity parts is investigated in this study using the assembly of the key components, the microtarget component TMP (thermomechanical package) and the hohlraum in ICF (inertial confinement fusion) research, as examples. A clamping force-assembly force mapping model based on multisource microforce sensors was developed to overcome the incapacity of microscopic vision to properly identify the condition of components after contact. The ICF microtarget flexible assembly system, which integrates multisource microforce sensing and a six degrees of freedom micromotion sliding table, is presented to address the constraint that the standard microassembly approach is difficult to operate once the parts contact. This method can detect contact force down to the mN level, modify deviation of the component posture efficiently, and achieve nondestructive ICF microtarget assembly at the end. Full article

(This article belongs to the Special Issue Advanced Actuation, Intelligent Sensor and Precise Manipulation Technology in Human–Robot Interaction)

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