Research

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16 pages, 5470 KiB

Open AccessArticle

Design and Evaluation of an Adjustable Compliant Constant-Force Microgripper

by Jiahang He, Yinong Liu, Chunbiao Yang, Zongdi Tong and Guangwei Wang

Micromachines 2024, 15(1), 52; https://0-doi-org.brum.beds.ac.uk/10.3390/mi15010052 - 26 Dec 2023

Viewed by 742

Precise control of the manipulating force within an appropriate range is crucial to prevent potential damage to the operating object. However, achieving accurate force control through force feedback is challenging in micro-scale applications. This study presents the design of a quasi-zero stiffness-compliant constant-force [...] Read more.

Precise control of the manipulating force within an appropriate range is crucial to prevent potential damage to the operating object. However, achieving accurate force control through force feedback is challenging in micro-scale applications. This study presents the design of a quasi-zero stiffness-compliant constant-force microgripper with adjustable force output. The parameters of the constant-force mechanism are designed using a model-based optimization method. By utilizing this mechanism, a compliant microgripper capable of providing adjustable constant-force output is developed to overcome the limitation of traditional grippers that offer only a single constant force. Finite element analysis is performed to simulate the behavior and verify the stability of the constant-force output. Furthermore, an experimental platform is constructed to validate the mechanical properties of the developed microgripper. The experimental results demonstrate that the automatically optimized structural parameters enable the microgripper to achieve the desired constant-force value of 2 N with an adjustable range of 0.15 N. These findings provide a further basis for the application and promotion of compliant constant-force structures. Full article

(This article belongs to the Special Issue Intelligent Human-Assisted Robotic Systems: From Microrobots to Wearable Robots)

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17 pages, 4962 KiB

Open AccessArticle

A Dielectric Elastomer Actuator-Driven Vibro-Impact Crawling Robot

by Chuang Wu, Huan Yan, Anjiang Cai and Chongjing Cao

Micromachines 2022, 13(10), 1660; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13101660 - 02 Oct 2022

Cited by 10 | Viewed by 2087

Abstract

Over the last decade, many bio-inspired crawling robots have been proposed by adopting the principle of two-anchor crawling or anisotropic friction-based vibrational crawling. However, these robots are complicated in structure and vulnerable to contamination, which seriously limits their practical application. Therefore, a novel [...] Read more.

Over the last decade, many bio-inspired crawling robots have been proposed by adopting the principle of two-anchor crawling or anisotropic friction-based vibrational crawling. However, these robots are complicated in structure and vulnerable to contamination, which seriously limits their practical application. Therefore, a novel vibro-impact crawling robot driven by a dielectric elastomer actuator (DEA) is proposed in this paper, which attempts to address the limitations of the existing crawling robots. The novelty of the proposed vibro-impact robot lies in the elimination of anchoring mechanisms or tilted bristles in conventional crawling robots, hence reducing the complexity of manufacturing and improving adaptability. A comprehensive experimental approach was adopted to characterize the performance of the robot. First, the dynamic response of the DEA-impact constraint system was characterized in experiments. Second, the performance of the robot was extensively studied and the fundamental mechanisms of the vibro-impact crawling locomotion were analyzed. In addition, effects of several key parameters on the robot’s velocity were investigated. It is demonstrated that our robot can realize bidirectional motion (both forward and backward) by simple tuning of the key control parameters. The robot demonstrates a maximum forward velocity of 21.4 mm/s (equivalent to 0.71 body-length/s), a backward velocity of 16.9 mm/s, and a load carrying capacity of 9.5 g (equivalent to its own weight). The outcomes of this paper can offer guidelines for high-performance crawling robot designs, and have potential applications in industrial pipeline inspections, capsule endoscopes, and disaster rescues. Full article

(This article belongs to the Special Issue Intelligent Human-Assisted Robotic Systems: From Microrobots to Wearable Robots)

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15 pages, 9672 KiB

Open AccessArticle

Design and Experimental Research of 3-RRS Parallel Ankle Rehabilitation Robot

by Yupeng Zou, Andong Zhang, Qiang Zhang, Baolong Zhang, Xiangshu Wu and Tao Qin

Micromachines 2022, 13(6), 950; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13060950 - 16 Jun 2022

Cited by 17 | Viewed by 2573

Abstract

The ankle is a crucial joint that supports the human body weight. An ankle sprain will adversely affect the patient’s daily life, so it is of great significance to ensure its strength. To help patients with ankle dysfunction to carry out effective rehabilitation [...] Read more.

The ankle is a crucial joint that supports the human body weight. An ankle sprain will adversely affect the patient’s daily life, so it is of great significance to ensure its strength. To help patients with ankle dysfunction to carry out effective rehabilitation training, the bone structure and motion mechanism of the ankle were analyzed in this paper. Referring to the configuration of the lower-mobility parallel mechanism, a 3-RRS (R and S denote revolute and spherical joint respectively) parallel ankle rehabilitation robot (PARR) was proposed. The robot can realize both single and compound ankle rehabilitation training. The structure of the robot was introduced, and the kinematics model was established. The freedom of movement of the robot was analyzed using the screw theory, and the robot kinematics were analyzed using spherical analytics theory. A circular composite rehabilitation trajectory was planned, and the accuracy of the kinematics model was verified by virtual prototype simulation. The Multibody simulation results show that the trajectory of the target point is basically the same as the expected trajectory. The maximum trajectory error is about 2.5 mm in the simulation process, which is within the controllable range. The experimental results of the virtual prototype simulation show that the maximum angular deflection error of the three motors is 2° when running a circular trajectory, which meets the experimental requirements. Finally, a control strategy for passive rehabilitation training was designed, and the effectiveness of this control strategy was verified by a prototype experiment. Full article

(This article belongs to the Special Issue Intelligent Human-Assisted Robotic Systems: From Microrobots to Wearable Robots)

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15 pages, 4121 KiB

Open AccessArticle

Trajectory Modulation for Impact Reducing of Lower-Limb Exoskeletons

by Long Zhang, Guangkui Song, Chaobin Zou, Rui Huang, Hong Cheng and Dekun Hu

Micromachines 2022, 13(6), 816; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13060816 - 24 May 2022

Cited by 1 | Viewed by 1663

Abstract

Lower-limb exoskeletons have received considerable attention because of their effectiveness in walking assistance and rehabilitation for paraplegic patients. Excessive foot–ground impacts during walking make patients uncomfortable and even lead to injury. In this paper, we propose an optimized knee trajectory modulation (OKTM) for [...] Read more.

Lower-limb exoskeletons have received considerable attention because of their effectiveness in walking assistance and rehabilitation for paraplegic patients. Excessive foot–ground impacts during walking make patients uncomfortable and even lead to injury. In this paper, we propose an optimized knee trajectory modulation (OKTM) for foot–ground impact reduction. The OKTM can reduce the peak of ground reaction force (PGRF) by knee-joint trajectory modulation based on a parameters-optimizing spring-damping system. In addition, a hip trajectory modulation (HTM) is presented to compensate for torso pitch deflections due to the OKTM. Unlike traditional mechanical-device-based methods, the proposed OKTM and HTM require no bulky mechanical structures, and can adaptively adjust parameters to adapt to different impacts. We demonstrated the efficiency of the proposed approach in both simulations and experiments for engineering verifications. Results show that the approach can effectively reduce PGRF. Full article

(This article belongs to the Special Issue Intelligent Human-Assisted Robotic Systems: From Microrobots to Wearable Robots)

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13 pages, 2667 KiB

Open AccessArticle

A Trajectory Tracking Control Based on a Terminal Sliding Mode for a Compliant Robot with Nonlinear Stiffness Joints

by Zhibin Song, Tianyu Ma, Keke Qi, Emmanouil Spyrakos-Papastavridis, Songyuan Zhang and Rongjie Kang

Micromachines 2022, 13(3), 409; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13030409 - 04 Mar 2022

Cited by 2 | Viewed by 2045

Abstract

A nonlinear stiffness actuator (NSA) can achieve high torque/force resolution in the low stiffness range and high bandwidth in the high stiffness range. However, for the NSA, due to the imperfect performance of the elastic mechanical component such as friction, hysteresis, and unmeasurable [...] Read more.

A nonlinear stiffness actuator (NSA) can achieve high torque/force resolution in the low stiffness range and high bandwidth in the high stiffness range. However, for the NSA, due to the imperfect performance of the elastic mechanical component such as friction, hysteresis, and unmeasurable energy consumption caused by former factors, it is more difficult to achieve accurate position control compared to the rigid actuator. Moreover, for a compliant robot with multiple degree of freedoms (DOFs) driven by NSAs, the influence of every NSA on the trajectory of the end effector is different and even coupled. Therefore, it is a challenge to implement precise trajectory control on a robot driven by such NSAs. In this paper, a control algorithm based on the Terminal Sliding Mode (TSM) approach is proposed to control the end effector trajectory of the compliant robot with multiple DOFs driven by NSAs. This control algorithm reduces the coupling of the driving torque, and mitigates the influence of parametric variation. The closed-loop system’s finite time convergence and stability are mathematically established via the Lyapunov stability theory. Moreover, under the same experimental conditions, by the comparison between the Proportion Differentiation (PD) controller and the controller using TSM method, the algorithm’s efficacy is experimentally verified on the developed compliant robot. The results show that the trajectory tracking is more accurate for the controller using the TSM method compared to the PD controller. Full article

(This article belongs to the Special Issue Intelligent Human-Assisted Robotic Systems: From Microrobots to Wearable Robots)

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16 pages, 6452 KiB

Open AccessArticle

A Novel Feature Extraction Algorithm and System for Flexible Integrated Circuit Packaging Substrate

by Dan Huang, Juan Wang, Yong Zeng, Yongxing Yu and Yueming Hu

Micromachines 2022, 13(3), 391; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13030391 - 28 Feb 2022

Cited by 2 | Viewed by 1811

Abstract

Aiming at the line defect detection of a flexible integrated circuit substrate (FICS) without reference template, there are some problems such as line discontinuity or inaccurate line defect location in the detection results. In order to address these problems, a line feature detection [...] Read more.

Aiming at the line defect detection of a flexible integrated circuit substrate (FICS) without reference template, there are some problems such as line discontinuity or inaccurate line defect location in the detection results. In order to address these problems, a line feature detection algorithm for extracting an FICS image is proposed. Firstly, FICS image acquisition is carried out by using the appearance defect intelligent detection system independently developed in our lab. Secondly, in the algorithm design of the software system, the binary image of the line image to be segmented is obtained after the color FICS image is classified by K-means, median filtering, morphological filling and closed operation. Finally, for an FICS binary image, an image segmentation model with convexity-preserving indirect regular level set is proposed, which is applied to extract the line features of an FICS image. Experiment results show that, compared with the CV model, LBF model, LCV model, LGIF model, Order-LBF model and RSF model, the proposed model can extract line features with high accuracy, and the line boundary is smooth, which lays an important foundation for high-precision measurement of line width and line distance and high-precision location of defects. Full article

(This article belongs to the Special Issue Intelligent Human-Assisted Robotic Systems: From Microrobots to Wearable Robots)

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15 pages, 5071 KiB

Open AccessArticle

Stiffness Analysis of Parallel Cable-Driven Upper Limb Rehabilitation Robot

by Yupeng Zou, Xiangshu Wu, Baolong Zhang, Qiang Zhang, Andong Zhang and Tao Qin

Micromachines 2022, 13(2), 253; https://0-doi-org.brum.beds.ac.uk/10.3390/mi13020253 - 02 Feb 2022

Cited by 4 | Viewed by 2342

Abstract

This paper studies the stiffness of the parallel cable-driven upper limb rehabilitation robot (PCUR). Firstly, it was derived that the static stiffness expression of the PCUR was composed of platform pose stiffness K_T and cable pose stiffness K_S. It indicated [...] Read more.

This paper studies the stiffness of the parallel cable-driven upper limb rehabilitation robot (PCUR). Firstly, it was derived that the static stiffness expression of the PCUR was composed of platform pose stiffness K_T and cable pose stiffness K_S. It indicated that the static stiffness of the PCUR was related to the cable tension, the arrangement of the cable, and the cable stiffness. Secondly, a simulation model in MATLAB/Simscape Multibody was built. Cable tension was applied to make the moving platform in a static equilibrium state. The stiffness of the PCUR and the external force on the moving platform were changed, and the motion characteristics of the moving platform were obtained. Finally, the position changes of the moving platform under different external forces were analyzed, and the motion laws of the moving platform under different stiffnesses were summarized. Full article

(This article belongs to the Special Issue Intelligent Human-Assisted Robotic Systems: From Microrobots to Wearable Robots)

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Review

Jump to: Research

31 pages, 451 KiB

Open AccessReview

Robotics Perception and Control: Key Technologies and Applications

by Jing Luo, Xiangyu Zhou, Chao Zeng, Yiming Jiang, Wen Qi, Kui Xiang, Muye Pang and Biwei Tang

Micromachines 2024, 15(4), 531; https://0-doi-org.brum.beds.ac.uk/10.3390/mi15040531 - 15 Apr 2024

Viewed by 592

Abstract

The integration of advanced sensor technologies has significantly propelled the dynamic development of robotics, thus inaugurating a new era in automation and artificial intelligence. Given the rapid advancements in robotics technology, its core area—robot control technology—has attracted increasing attention. Notably, sensors and sensor [...] Read more.

The integration of advanced sensor technologies has significantly propelled the dynamic development of robotics, thus inaugurating a new era in automation and artificial intelligence. Given the rapid advancements in robotics technology, its core area—robot control technology—has attracted increasing attention. Notably, sensors and sensor fusion technologies, which are considered essential for enhancing robot control technologies, have been widely and successfully applied in the field of robotics. Therefore, the integration of sensors and sensor fusion techniques with robot control technologies, which enables adaptation to various tasks in new situations, is emerging as a promising approach. This review seeks to delineate how sensors and sensor fusion technologies are combined with robot control technologies. It presents nine types of sensors used in robot control, discusses representative control methods, and summarizes their applications across various domains. Finally, this survey discusses existing challenges and potential future directions. Full article

(This article belongs to the Special Issue Intelligent Human-Assisted Robotic Systems: From Microrobots to Wearable Robots)

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