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34 pages, 16479 KiB

Open AccessArticle

Development of a Six-Degree-of-Freedom Deep-Sea Water-Hydraulic Manipulator

by Heng Gao, Defa Wu, Chuanqi Gao, Changkun Xu, Xing Yang and Yinshui Liu

J. Mar. Sci. Eng. 2024, 12(10), 1696; https://doi.org/10.3390/jmse12101696 - 24 Sep 2024

Cited by 3 | Viewed by 1635

With the advancement of deep-sea exploration, the demand for underwater manipulators capable of long-duration heavy-duty operations has intensified. Water-hydraulic systems exhibit less viscosity variation with increasing depth than oil-based systems, offering better adaptability to deep-sea conditions. Using seawater as the driving medium inherently eliminates issues such as oil contamination by water, frequent maintenance limiting underwater operation time, and environmental pollution caused by oil leaks. This paper introduces a deep-sea manipulator directly driven by seawater from the deep-sea environment. To address the challenges of weak lubrication and high corrosion associated with water hydraulics, a reciprocating plunger seal was adopted, and a water-hydraulic actuator was developed. The installation positions of actuator hinges and maximum output force requirements were optimized using particle swarm optimization (PSO), effectively reducing the manipulator’s self-weight. Through kinematic and inverse kinematic analyses and joint performance tests, a six-degree-of-freedom water-hydraulic manipulator was designed with a maximum reach of 2.5 m, a lifting capacity of 5000 N, and end-effector positioning accuracy within 18 mm. Full article

(This article belongs to the Section Ocean Engineering)

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18 pages, 3266 KiB

Open AccessArticle

Effect of Tampering on On-Road and Off-Road Diesel Vehicle Emissions

by Barouch Giechaskiel, Fabrizio Forloni, Massimo Carriero, Gianmarco Baldini, Paolo Castellano, Robin Vermeulen, Dimitrios Kontses, Pavlos Fragkiadoulakis, Zissis Samaras and Georgios Fontaras

Sustainability 2022, 14(10), 6065; https://doi.org/10.3390/su14106065 - 17 May 2022

Cited by 14 | Viewed by 4171

Abstract

Illegal manipulation (i.e., tampering) of vehicles is a severe problem because vehicle emissions increase orders of magnitude and significantly impact the environment and human health. This study measured the emissions before and after representative approaches of tampering of two Euro 6 Diesel light-duty passenger cars, two Euro VI Diesel heavy-duty trucks, and a Stage IV Diesel non-road mobile machinery (NRMM) agricultural tractor. With tampering of the selective catalytic reduction (SCR) for NO_x, the NO_x emissions increased by more than one order of magnitude exceeding 1000 mg/km (or mg/kWh) for all vehicles, reaching older Euro or even pre-Euro levels. The tampering of the NO_x sensor resulted in relatively low NO_x increases, but significant ammonia (NH₃) slip. The particle number emissions increased three to four orders of magnitude, reaching 6–10 × 10¹² #/km for the passenger car (one order of magnitude higher than the current regulation limit). The tampered passenger car’s NO_x and particle number emissions were one order of magnitude higher even compared to the emissions during a regeneration event. This study confirmed that (i) tampering with the help of an expert technician is still possible, even for vehicles complying with the current Euro standards, although this is not allowed by the regulation; (ii) tampering results in extreme increases in emissions. Full article

(This article belongs to the Special Issue Emissions from Road Transportation and Vehicle Management)

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14 pages, 1975 KiB

Open AccessArticle

Position-Based Impedance Control Design for a Hydraulically Actuated Series Elastic Actuator

by Pauli Mustalahti and Jouni Mattila

Energies 2022, 15(7), 2503; https://doi.org/10.3390/en15072503 - 29 Mar 2022

Cited by 7 | Viewed by 2639

Abstract

Series elastic actuators (SEAs) have become a common actuation method in torque-controlled electric lightweight arm applications that physically interact with the environment in assembly tasks. Compared to traditional actuators, SEAs can provide high force fidelity, shock tolerance, and force sensing for interaction control. Considering inherent system dynamics and the variable stiffness of the fluid, the control design for hydraulic SEAs (HSEAs) that lead into fifth-order system is a challenging task. As a novelty, a full state feedback controller design for the developed fifth-order HSEA system is presented to serve as an inner-loop controller to handle highly nonlinear dynamics behavior. In addition, as an outer-loop impedance controller for HSEAs in heavy-duty applications, the position-based impedance controller is designed to handle control of the HSEA system during the contact motion. Experimental results with a one-degree-of-freedom real-size experimental setup with a payload of 200 kilos demonstrates the effectiveness of the proposed HSEA control methods both in the free-space motion and in a contact impedance motion. Full article

(This article belongs to the Special Issue New Insights of Intelligent and Integrated Fluid Power Systems)

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19 pages, 2790 KiB

Open AccessArticle

Motion Control of a Hydraulic Manipulator with Adaptive Nonlinear Model Compensation and Comparative Experiments

by Yangxiu Xia, Yong Nie, Zheng Chen, Litong Lyu and Po Hu

Machines 2022, 10(3), 214; https://doi.org/10.3390/machines10030214 - 18 Mar 2022

Cited by 7 | Viewed by 3236

Abstract

Hydraulic manipulators play an irreplaceable role in many heavy-duty applications. Currently, there are stronger demands for the hydraulic manipulator to achieve high precision, as well as high force/power. However, due to the inherent nonlinearities of its high-order dynamics, the precision of the manipulator has been a common weakness compared with electrically driven ones. Thus, in this paper, a nonlinear adaptive robust control method for the hydraulic manipulator is proposed. To make the controller more applicable to practical engineering projects, this study tried to control each joint independently instead of directly based on the complicated multi-degree high-order dynamics, while guaranteeing the control precision by the adaptive nonlinear model compensation, as well as a robust feedback design. The closed-loop control performance was theoretically verified. Besides, several sets of comparative motion tracking experiments were conducted, and the proposed closed-loop system achieved high precision under different trajectories and postures. Full article

(This article belongs to the Special Issue Advanced Control of Industrial Electro-Hydraulic Systems)

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12 pages, 372 KiB

Open AccessReview

Soldier Load Carriage, Injuries, Rehabilitation and Physical Conditioning: An International Approach

by Robin Orr, Rodney Pope, Thiago Jambo Alves Lopes, Dieter Leyk, Sam Blacker, Beatriz Sanz Bustillo-Aguirre and Joseph J. Knapik

Int. J. Environ. Res. Public Health 2021, 18(8), 4010; https://doi.org/10.3390/ijerph18084010 - 11 Apr 2021

Cited by 39 | Viewed by 9542

Abstract

Soldiers are often required to carry heavy loads that can exceed 45 kg. The physiological costs and biomechanical responses to these loads, whilst varying with the contexts in which they are carried, have led to soldier injuries. These injuries can range from musculoskeletal injuries (e.g., joint/ligamentous injuries and stress fractures) to neurological injuries (e.g., paresthesias), and impact on both the soldier and the army in which they serve. Following treatment to facilitate initial recovery from injuries, soldiers must be progressively reconditioned for load carriage. Optimal conditioning and reconditioning practices include load carriage sessions with a frequency of one session every 10–14 days in conjunction with a program of both resistance and aerobic training. Speed of march and grade and type of terrain covered are factors that can be adjusted to manipulate load carriage intensity, limiting the need to adjust load weight alone. Factors external to the load carriage program, such as other military duties, can also impart physical loading and must be considered as part of any load carriage conditioning/reconditioning program. Full article

(This article belongs to the Special Issue Tactical Forces Injury Risk Management)

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