| 1. |
- Jung, Taerang, et al.
(författare)
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Boom energy recuperation system and control strategy for hydraulic hybrid excavators
- 2022
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Ingår i: Automation in Construction. - : ELSEVIER. - 0926-5805 .- 1872-7891. ; 135
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a boom potential energy recovery hydraulic system for an excavator and its controller is proposed and evaluated. It is a trend in the construction machinery sector to adopt hybrid systems to recuperate potential energy from heavy loads. Many studies have been conducted to improve the efficiency of boom potential energy recovery. However, most of the proposed solutions have limitations regarding commercialization due to low controllability and high cost. The proposed system in this paper uses only electronically controlled hydraulic components. Different operation modes are defined to increase performance, efficiency or a balance between the two. The system is mathematically analysed to derive a control strategy that is able to increase machine efficiency and control performance while maintaining its controllability. The system and control strategy are applied to a prototype machine, a Volvo 30-ton class excavator, to verify the effectiveness of the proposed approach. Experimental results demonstrate that the working cycle becomes around 3% faster, and the fuel consumption becomes around 9% lower than the operation in non-hybrid mode.
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| 2. |
- Nostrani, Marcos Paulo, et al.
(författare)
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Multi-Chamber Actuator Using Digital Pump for Position and Velocity Control Applied in Aircraft
- 2023
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Ingår i: International Journal of Fluid Power. - : RIVER PUBLISHERS. - 1439-9776 .- 2332-1180. ; 24:1
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a multi-chamber hydraulic actuator controlled by digital pumps and on/off valves, in order to improve the efficiency of hydraulic systems applied in aircraft for flight control. Hydraulic positioning systems are used in many different applications, such as mobile machinery, industry and aerospace. In aircraft, the hydraulic actuators are used at flight control surfaces, cargo doors, steering, landing gear and so one. However, the mas-sive use of resistive control techniques, which throttles the passages of the hydraulic fluid, associated with internal leakage of the hydraulic components, make these systems low energy efficient. In order to improve their energy efficiency, digital hydraulics emerges as a promising solution mainly for mobile applications. In this paper a hydraulic positioning system for aircraft control surfaces using a multi-chamber actuator controlled by on/off valves and a digital pump is proposed. The use of a digital pump with three fixed displacement pumps can provide eight different volumetric displacement out-puts. The multi-chamber actuator with four areas can operate in two different modes, normal or regenerative, resulting in six different equivalent areas. The regenerative mode allows the actuator to achieve higher actuation velocity values with smaller pumps. These equivalent areas combined with the dif-ferent supplied flow rates can deliver 43 different discrete output velocity values for the actuator, in steady-state. For the system dynamic analyses, three mathematical simulation models were developed using MATLAB/Simulink and Hopsan, one for the digital system, and two for the conventional solutions applied in aircraft (Servo Hydraulic Actuators (SHA) and Electro Hydrostatic Actuator (EHA)). The simulation results demonstrate that the digital actuator can achieve, for position control, a maximum position error, in a steady-state, of 0.7 mm. From the energy consumption point of view, the digital circuit consumes 31 times less energy when compared with the SHA and 1.7 when compared to the EHA, resulting in an energy efficiency of 54%.
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| 3. |
- Raduenz, Henrique, 1990-, et al.
(författare)
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Energy Management Based on Neural Networks for a Hydraulic Hybrid Wheel Loader
- 2020
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Ingår i: 2020 IEEE Global Fluid Power Society PhD Symposium. - 9781728141381
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Konferensbidrag (refereegranskat)abstract
- This paper presents a method to derive optimized energy management strategies for a hydraulic hybrid wheel loader. Energy efficiency is a key aspect for the sustainability of off-road mobile machines. Energy management strategies for on-road hybrid vehicles cannot be directly applied to off-road hybrid machines. One significant reason is that there are added degrees of freedom with respect to how power can be recovered, exchanged and reused in the different functions, such as drivetrain or work functions. This results in more complex energy management strategies being derived. This paper presents an analysis and preliminary conclusions for a proposed method to derive optimised online energy management strategies for a hydraulic hybrid wheel loader. Dynamic programming is used to obtain optimal offline energy management strategies for a series of drive cycles. The results are used as examples to train a neural network. The trained neural network then implements the energy management strategy and is used to make optimised control decisions. Through simulation, the neural network’s ability to learn the dynamic programming decision-making process is shown, resulting in the machine operating with fuel consumption similar to that of the offline optimal energy management strategy. Aspects of simplicity to model these machines for dynamic programming optimisation, the data necessary to train the network, the training process, variables used to learn the dynamic programming decision-making process and the robustness of the network when facing unseen operational conditions are discussed. The paper demonstrates the simplicity of the method for taking into account variables that affect the control decisions, therefore achieving optimised solutions.
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| 4. |
- Raduenz, Henrique, et al.
(författare)
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Energy Management Based on Neural Networks for a Hydraulic Hybrid Wheel Loader
- 2022
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Ingår i: International Journal of Fluid Power. - : RIVER PUBLISHERS. - 1439-9776 .- 2332-1180. ; 23:3, s. 411-432
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a method to derive optimised energy management strate-gies for a hydraulic hybrid wheel loader. Energy efficiency is a key aspect for the sustainability of off-road mobile machines. Energy management strategies for on-road hybrid vehicles cannot be directly applied to off-road hybrid machines. One significant reason is that there are added degrees of freedom with respect to how power can be recovered, exchanged and reused in the different functions, such as drivetrain or work functions. This results in more complex energy management strategies being derived. This paper presents an analysis and preliminary conclusions for a proposed method to derive optimised online energy management strategies for a hydraulic hybrid wheel loader. Dynamic programming is used to obtain optimal offline energy management strategies for a series of drive cycles. The results are used as examples to train a neural network. The trained neural network then implements the energy management strategy and is used to make optimised control decisions. Through simulation, the neural networks ability to learn the dynamic programming decision-making process is shown, resulting in the machine operating with fuel consumption similar to that of the offline optimal energy management strategy. Aspects of simplicity to model these machines for dynamic programming optimisation, the data necessary to train the network, the training process, variables used to learn the dynamic pro-gramming decision-making process and the robustness of the network when facing unseen operational conditions are discussed. The paper demonstrates the simplicity of the method for taking into account variables that affect the control decisions, therefore achieving optimised solutions.
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| 5. |
- Raduenz, Henrique, et al.
(författare)
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Extended Analysis of a Valve-Controlled System with Multi-Chamber Actuator
- 2022
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Ingår i: International Journal of Fluid Power. - : RIVER PUBLISHERS. - 1439-9776 .- 2332-1180. ; 23:1, s. 79-108
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Tidskriftsartikel (refereegranskat)abstract
- This paper outlines an extended analysis on how multi-chamber actuators can improve the efficiency of valve-controlled systems. Resistive control is a major source of energy losses in valve-controlled systems that share the same pump to drive multiple loads. By combining different chambers, the load on multi-chamber actuators can be transformed into different pressure and flow rate levels. This allows the adaptation of its load to the loads on other actuators. This can lead to a reduction of resistive control energy losses that occur between pump and actuators when driven simultaneously. As a case study to highlight how the system efficiency can be improved, a load sensing system with a conventional and a multi-chamber actuator is analysed. The equations that describe the system steady state behaviour are presented to evaluate the effect of the load transformations on the system efficiency. A disadvantage of such architecture is the fact that load transformations result in different actuator speeds. To reduce this effect, a compensation factor for the command signal to the proportional valve is presented. The highlight from this paper is the potential for efficiency improvement enabled by the adoption of multi-chamber actuators in a valve-controlled architecture. Further research is required for the selection of number of chambers and their areas since they directly affect the system efficiency.
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| 6. |
- Raduenz, Henrique, 1990-, et al.
(författare)
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Improving the efficiency of valve-controlled systems by using multi-chamber actuators
- 2021
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Ingår i: Proceedings of the 17:th Scandinavian International Conference on Fluid Power, SICFP’21, June 1-2, 2021, Linköping, Sweden. - : Linköping University Electronic Press. - 9789179290139 ; , s. 224-236
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Konferensbidrag (refereegranskat)abstract
- This paper outlines how multi-chamber actuatorscan improve the efficiency of valve-controlled systems.Resistive control is a major source of energy losses invalve-controlled systemsthat share the same pumpto drive multiple loads. In the proposed concept, by selectingdifferent chambers,the load on the multi-chamber actuator can be transformed into different pressure and flow rate levels, allowingthe adaptation of its load to the loads on otheractuators. Thiscan lead to a reduction of resistive control energy losses that occur between pump and actuatorswhen driven simultaneously.Suchsystemsareseen as an intermediate solution between resistive conventionalhydraulics and throttle-less digital hydraulics. As a casestudyto highlight the possible efficiency improvement, a concept of a load sensing system with a conventional and a multi-chamber actuatoris analysed. To determine itsefficiency,the equations that describe its static behaviour are presented. Evaluating them for a set ofload forces and speeds demonstrates how the load transformation occursand how it canimprove efficiency.
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| 7. |
- Raduenz, Henrique, et al.
(författare)
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Multi-Chamber Actuator Mode Selection through Reinforcement Learning-Simulations and Experiments
- 2022
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 15:14
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the development and implementation of a reinforcement learning agent as the mode selector for a multi-chamber actuator in a load-sensing architecture. The agent selects the mode of the actuator to minimise system energy losses. The agent was trained in a simulated environment and afterwards deployed to the real system. Simulation results indicated the capability of the agent to reduce energy consumption, while maintaining the actuation performance. Experimental results showed the capability of the agent to learn via simulation and to control the real system.
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