Pub Date : 2018-07-01DOI: 10.1109/GFPS.2018.8472386
Meike Ernst, M. Ivantysynova
Construction, agriculture, forestry, aerospace equip- ment: axial piston machines of swash plate design (APMSPD) are the positive displacement machines of choice in a wide variety of hydraulic systems. The performance of these highly efficient units is delicately hinged on the rigorous design of three major lubricating interfaces, each striving to keep the machine’s moving components a hair’s width apart in order to avert poten- tially catastrophic metal-to-metal contact, whilst simultaneously limiting the leakage of high-pressure fluid into the unit’s low- pressure case. Of the three, the most difficult in its conception for these duties is the piston-cylinder interface, owing to the fact that especially during high-pressure operation, the pistons of APMSPD must bear a considerable side load. The measure of challenge this side load presents is heavily modulated by the choice of lubricant (i.e., the hydraulic system’s working fluid). While the use of oil still dominates the hydraulics industry, the past few decades have seen the re-emergence of water hydraulics. In its non-toxicity, its inflammability, its availability, its low cost and green footprint, water embodies an almost ideal hydraulic fluid; however, the illusion unravels in giving consideration to its viscosity, which is low enough to raise serious load-support concerns for the aforementioned interface, therewith barricading the design of marketable APMSPD for high-pressure operation with water. In aiming to enable such operation, micro surface shaping on the bores in the cylinder block through which the pistons in APMSPD move has been examined as an effective means of enhancing load support. The focus of the present work is a surface profile that has the walls of these bores curving inwards. A past exploration of this profile defined its shape via a radius and a shift; the present investigation refines that definition to two radii and a shift, thereby significantly opening the design space. In a simulation study spanning several different operating conditions, the effect of dimensional variations of this design on load support and power loss is captured with a non-isothermal fluid-structure interaction model developed by the Maha Fluid Power Research Center. The resulting design trends reveal the potential of this surface profile to handle these operating conditions.
{"title":"Axial Piston Machine Cylinder Block Bore Surface Profile for High-Pressure Operating Conditions with Water as Working Fluid","authors":"Meike Ernst, M. Ivantysynova","doi":"10.1109/GFPS.2018.8472386","DOIUrl":"https://doi.org/10.1109/GFPS.2018.8472386","url":null,"abstract":"Construction, agriculture, forestry, aerospace equip- ment: axial piston machines of swash plate design (APMSPD) are the positive displacement machines of choice in a wide variety of hydraulic systems. The performance of these highly efficient units is delicately hinged on the rigorous design of three major lubricating interfaces, each striving to keep the machine’s moving components a hair’s width apart in order to avert poten- tially catastrophic metal-to-metal contact, whilst simultaneously limiting the leakage of high-pressure fluid into the unit’s low- pressure case. Of the three, the most difficult in its conception for these duties is the piston-cylinder interface, owing to the fact that especially during high-pressure operation, the pistons of APMSPD must bear a considerable side load. The measure of challenge this side load presents is heavily modulated by the choice of lubricant (i.e., the hydraulic system’s working fluid). While the use of oil still dominates the hydraulics industry, the past few decades have seen the re-emergence of water hydraulics. In its non-toxicity, its inflammability, its availability, its low cost and green footprint, water embodies an almost ideal hydraulic fluid; however, the illusion unravels in giving consideration to its viscosity, which is low enough to raise serious load-support concerns for the aforementioned interface, therewith barricading the design of marketable APMSPD for high-pressure operation with water. In aiming to enable such operation, micro surface shaping on the bores in the cylinder block through which the pistons in APMSPD move has been examined as an effective means of enhancing load support. The focus of the present work is a surface profile that has the walls of these bores curving inwards. A past exploration of this profile defined its shape via a radius and a shift; the present investigation refines that definition to two radii and a shift, thereby significantly opening the design space. In a simulation study spanning several different operating conditions, the effect of dimensional variations of this design on load support and power loss is captured with a non-isothermal fluid-structure interaction model developed by the Maha Fluid Power Research Center. The resulting design trends reveal the potential of this surface profile to handle these operating conditions.","PeriodicalId":273799,"journal":{"name":"2018 Global Fluid Power Society PhD Symposium (GFPS)","volume":"107 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134308412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.1109/GFPS.2018.8472384
A. Utkin, A. Gimadiev
The use of a vortex-throttling device to reduce the pressure of fluid flow is a promising area, since these devices have a high hydraulic resistance coefficient at a large flow area and have high reliability due to the absence of moving parts. The purpose of this paper is conduct experimental and theoretical studies of the hydraulic characteristics of vortex throttle and a package of vortex throttles, taking into account the effect of backpressure and the mutual arrangement of the throttles in the package.1 Pressure, velocity and other parameter distribution fields in the flow part of the vortex throttle were obtained by means of CFD simulation in the Ansys CFX software. The main pressure drop occurs on the throttling orifice, in which, with significant pressure drop, a cavitations effect occurs. The ratio of the Euler numbers for reverse (with a swirling flow) to direct (without a swirling flow) connections of the throttle is 5.3, which allows it to be also used as a fluidic diode. To obtain a high hydraulic resistance, a series connection of the vortex throttles to the package is used. The study was conducted for a package of three and four vortex throttles at Reynolds numbers $10 ^{3}ldots 26cdot 10 ^{3}$ and pressure drop of up to 10 MPa. The obtained results show that the backpressure value and the distance between throttles have a negligible effect on the package pressure drop. It is established that on each of the successively installed vortex throttles an equal pressure drop is realized within an error of 3%. The calculated data correlates well with the experimental point, which confirms the adequacy of the developed mathematical model. The obtained results allow calculating the parameters of the pressure reduction devices based on the vortex throttles. The material is of interest to design organizations involved in developing sample conditioning systems and throttling devices for large pressure drops.
{"title":"Numerical and Experimental Study of the Fluidic Vortex-throttling Device","authors":"A. Utkin, A. Gimadiev","doi":"10.1109/GFPS.2018.8472384","DOIUrl":"https://doi.org/10.1109/GFPS.2018.8472384","url":null,"abstract":"The use of a vortex-throttling device to reduce the pressure of fluid flow is a promising area, since these devices have a high hydraulic resistance coefficient at a large flow area and have high reliability due to the absence of moving parts. The purpose of this paper is conduct experimental and theoretical studies of the hydraulic characteristics of vortex throttle and a package of vortex throttles, taking into account the effect of backpressure and the mutual arrangement of the throttles in the package.1 Pressure, velocity and other parameter distribution fields in the flow part of the vortex throttle were obtained by means of CFD simulation in the Ansys CFX software. The main pressure drop occurs on the throttling orifice, in which, with significant pressure drop, a cavitations effect occurs. The ratio of the Euler numbers for reverse (with a swirling flow) to direct (without a swirling flow) connections of the throttle is 5.3, which allows it to be also used as a fluidic diode. To obtain a high hydraulic resistance, a series connection of the vortex throttles to the package is used. The study was conducted for a package of three and four vortex throttles at Reynolds numbers $10 ^{3}ldots 26cdot 10 ^{3}$ and pressure drop of up to 10 MPa. The obtained results show that the backpressure value and the distance between throttles have a negligible effect on the package pressure drop. It is established that on each of the successively installed vortex throttles an equal pressure drop is realized within an error of 3%. The calculated data correlates well with the experimental point, which confirms the adequacy of the developed mathematical model. The obtained results allow calculating the parameters of the pressure reduction devices based on the vortex throttles. The material is of interest to design organizations involved in developing sample conditioning systems and throttling devices for large pressure drops.","PeriodicalId":273799,"journal":{"name":"2018 Global Fluid Power Society PhD Symposium (GFPS)","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132473732","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.1109/GFPS.2018.8472361
O. Zalogin, A. Noskov, Aleksey Cherevatov
The harmonic linearization method (dithering) is widely used in hydraulic servo systems; however, generated longitudinal oscillations of the spool result in unsteady hydrodynamic processes in spool valve throttle gap and change the structure of the flow that influences metering characteristics. The article deals with study of throttle gap flow structure in non-stationary conditions. The study was conducted by using a two-dimensional CFD model based on dynamic meshes in the ANSYS Fluent software package at various values of the spool valve oscillation frequencies. CFD model was successfully validated against experimental data from the literature. The results of numerical study of flow structure and flow parameters (such as the coefficient of jet contraction, the pressure diagram along a flow line) in the throttle gap are presented. The frequency dependence of the phase shift magnitude of volumetric flow rate oscillation relative to the harmonic valve oscillation is determined. Obtained model can be used for development of the refined one-dimensional mathematical model and simulation model of specified type devices
{"title":"CFD Analysis Of Fluid Flow Inside The Spool Valve At Unsteady Modes","authors":"O. Zalogin, A. Noskov, Aleksey Cherevatov","doi":"10.1109/GFPS.2018.8472361","DOIUrl":"https://doi.org/10.1109/GFPS.2018.8472361","url":null,"abstract":"The harmonic linearization method (dithering) is widely used in hydraulic servo systems; however, generated longitudinal oscillations of the spool result in unsteady hydrodynamic processes in spool valve throttle gap and change the structure of the flow that influences metering characteristics. The article deals with study of throttle gap flow structure in non-stationary conditions. The study was conducted by using a two-dimensional CFD model based on dynamic meshes in the ANSYS Fluent software package at various values of the spool valve oscillation frequencies. CFD model was successfully validated against experimental data from the literature. The results of numerical study of flow structure and flow parameters (such as the coefficient of jet contraction, the pressure diagram along a flow line) in the throttle gap are presented. The frequency dependence of the phase shift magnitude of volumetric flow rate oscillation relative to the harmonic valve oscillation is determined. Obtained model can be used for development of the refined one-dimensional mathematical model and simulation model of specified type devices","PeriodicalId":273799,"journal":{"name":"2018 Global Fluid Power Society PhD Symposium (GFPS)","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129279682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.1109/gfps.2018.8472378
{"title":"GFPS 2018 TOC","authors":"","doi":"10.1109/gfps.2018.8472378","DOIUrl":"https://doi.org/10.1109/gfps.2018.8472378","url":null,"abstract":"","PeriodicalId":273799,"journal":{"name":"2018 Global Fluid Power Society PhD Symposium (GFPS)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124653929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.1109/GFPS.2018.8472359
M. Rückert, O. Reinertz, K. Schmitz
Viscosity measurements in fluid power are a standard tool to gain information on the fluid and its condition. The results are required for system design and simulation. Within fluid power systems, high pressures are common in piston-bushing contacts or lubricating gaps for example. A popular approach to high-pressure measurements is falling body viscometry. The terminal velocity of a falling body inside a fluid-filled tube is used to determine the fluids viscosity. However, falling body viscometry is prone to inaccuracies which raises questions regarding the reliability of the measurement principle and the measurement itself. Eccentricity, tumbling and material pairings above all other factors are responsible for deviations regarding terminal velocity of the falling body. Studies do indicate highly varying falling times at constant conditions, but a significant statistical analysis has not been done yet. Therefore, using the viscometer at IFAS, a statistical falling time evaluation is carried out and different falling body designs are compared to each other. Afterwards, the most advantageous geometry is identified.
{"title":"High Pressure Rheology – On the Statistics of Falling Body Viscometers","authors":"M. Rückert, O. Reinertz, K. Schmitz","doi":"10.1109/GFPS.2018.8472359","DOIUrl":"https://doi.org/10.1109/GFPS.2018.8472359","url":null,"abstract":"Viscosity measurements in fluid power are a standard tool to gain information on the fluid and its condition. The results are required for system design and simulation. Within fluid power systems, high pressures are common in piston-bushing contacts or lubricating gaps for example. A popular approach to high-pressure measurements is falling body viscometry. The terminal velocity of a falling body inside a fluid-filled tube is used to determine the fluids viscosity. However, falling body viscometry is prone to inaccuracies which raises questions regarding the reliability of the measurement principle and the measurement itself. Eccentricity, tumbling and material pairings above all other factors are responsible for deviations regarding terminal velocity of the falling body. Studies do indicate highly varying falling times at constant conditions, but a significant statistical analysis has not been done yet. Therefore, using the viscometer at IFAS, a statistical falling time evaluation is carried out and different falling body designs are compared to each other. Afterwards, the most advantageous geometry is identified.","PeriodicalId":273799,"journal":{"name":"2018 Global Fluid Power Society PhD Symposium (GFPS)","volume":"1951 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129194224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.1109/GFPS.2018.8472368
Otto Gottberg, J. Kajaste, T. Minav, Heikki Kauranne, O. Calonius, M. Pietola
This paper presents the experimental results of the study performed with an electrified small sized excavator, a 1.1- tonne JCB Micro, equipped with conventional hydraulics. The highlighted points in this study are the overall energy balance of the electro-hydraulic powertrain of this excavator and the power losses in individual components. The measured energy balance of the electric motor powered system is compared with the simulation data obtained from a preliminary simulation model of the system. The empirical evidence and the results of the preliminary simulation model will be in future research utilized to discover and compare new alternatives for powertrain architectures.
{"title":"Energy Balance of Electro-Hydraulic Powertrain in a Micro Excavator","authors":"Otto Gottberg, J. Kajaste, T. Minav, Heikki Kauranne, O. Calonius, M. Pietola","doi":"10.1109/GFPS.2018.8472368","DOIUrl":"https://doi.org/10.1109/GFPS.2018.8472368","url":null,"abstract":"This paper presents the experimental results of the study performed with an electrified small sized excavator, a 1.1- tonne JCB Micro, equipped with conventional hydraulics. The highlighted points in this study are the overall energy balance of the electro-hydraulic powertrain of this excavator and the power losses in individual components. The measured energy balance of the electric motor powered system is compared with the simulation data obtained from a preliminary simulation model of the system. The empirical evidence and the results of the preliminary simulation model will be in future research utilized to discover and compare new alternatives for powertrain architectures.","PeriodicalId":273799,"journal":{"name":"2018 Global Fluid Power Society PhD Symposium (GFPS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130507560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.1109/GFPS.2018.8472389
E. Frosina, G. Marinaro, A. Senatore, M. Pavanetto
This paper represents the results obtained with a preliminary numerical methodology adopted to reduce noise in axial piston pumps. Starting from a preliminary design (further called “Valve plate #1”), two different valve plates have been proposed comparing their contribution to reduction of flow ripple. The pump is an open circuit axial piston pump, swash plate designed with nine-piston and a maximum displacement of 65.9 cm3/rev. A three-dimensional CFD model of the first pump design has been built up with the commercial code PumpLinx®, developed by Simerics Inc. The numerical model has been validated, considering the pump rotation, fluid characteristic and leakages. The pump has been tested by the pump manufacturer in all the working conditions. The first valve plate design (“Valve plate #1”) has been modified optimizing the pre-compression relief groove design (“Valve plate #2”) and including a pre-compression filter volume (PCFV, “Valve plate #3”) The Valve plate #2, including an optimized pre-compression groove, has been designed mainly to improve the volumetric efficiency and as well as to reduce the flow ripple. The second solution (“Valve plate #3 has been obtained on the basis of the Valve plate #2, including a PCFV to reduce the reverse flow back to the cylinder chamber. All the designs presented in this paper have been modelled for minimizing the peak-to-peak discharge flow ripple at the pump full displacements and for the rotational speed of 1500rpm delivery pressure. The best geometry has been found demonstrating that, with the introduction of the PCFV into axial piston pump, the reverse flow has been drastically reduced up to 40%. This research is result of a collaboration among the University of Naples “Federico II” and the pump manufacturers Duplomatic MS and Continental Hydraulics Inc.
{"title":"Effects of PCFV and Pre-Compression Groove on the Flow Ripple Reduction in Axial Piston Pumps","authors":"E. Frosina, G. Marinaro, A. Senatore, M. Pavanetto","doi":"10.1109/GFPS.2018.8472389","DOIUrl":"https://doi.org/10.1109/GFPS.2018.8472389","url":null,"abstract":"This paper represents the results obtained with a preliminary numerical methodology adopted to reduce noise in axial piston pumps. Starting from a preliminary design (further called “Valve plate #1”), two different valve plates have been proposed comparing their contribution to reduction of flow ripple. The pump is an open circuit axial piston pump, swash plate designed with nine-piston and a maximum displacement of 65.9 cm3/rev. A three-dimensional CFD model of the first pump design has been built up with the commercial code PumpLinx®, developed by Simerics Inc. The numerical model has been validated, considering the pump rotation, fluid characteristic and leakages. The pump has been tested by the pump manufacturer in all the working conditions. The first valve plate design (“Valve plate #1”) has been modified optimizing the pre-compression relief groove design (“Valve plate #2”) and including a pre-compression filter volume (PCFV, “Valve plate #3”) The Valve plate #2, including an optimized pre-compression groove, has been designed mainly to improve the volumetric efficiency and as well as to reduce the flow ripple. The second solution (“Valve plate #3 has been obtained on the basis of the Valve plate #2, including a PCFV to reduce the reverse flow back to the cylinder chamber. All the designs presented in this paper have been modelled for minimizing the peak-to-peak discharge flow ripple at the pump full displacements and for the rotational speed of 1500rpm delivery pressure. The best geometry has been found demonstrating that, with the introduction of the PCFV into axial piston pump, the reverse flow has been drastically reduced up to 40%. This research is result of a collaboration among the University of Naples “Federico II” and the pump manufacturers Duplomatic MS and Continental Hydraulics Inc.","PeriodicalId":273799,"journal":{"name":"2018 Global Fluid Power Society PhD Symposium (GFPS)","volume":"68 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123242668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.1109/GFPS.2018.8472398
G. Makaryants, L. Rodionov, Danila Radin
This paper demonstrates that a tunable Helmholtz resonator (HR) can exist in a gear pump as a broadband absorber. It is common to encounter a problem of the pulsating pressure of working fluid in current hydraulic systems. This pulsation load negatively affects the durability of all elements of the system. Hence the unregulated HR is narrowband silencer, which is not effective over the entire frequency range. Thus it is necessary to design an adaptive HR, which changes its cavity volume so that the natural frequency of resonator corresponds with the excitation frequency. Designing this device requires a lot of calculation. Therefore, the main purpose of the article is creating an automatic system for calculating a tunable resonator. The automatic system for calculating the tuned resonator is created in the software package Microsoft Excel. In the process of creating the system, the existing method of design calculation was made more accurate and a methodology for calculating the absorber’s efficiency was developed. The result of this work is a fully automatic system for calculating a tunable resonator, which can significantly reduce the time, and hence the design cost of this unit. Finally, the adequacy of used methods was confirmed.
{"title":"Creating an automatic system it for calculating a tunable Helmholtz resonator","authors":"G. Makaryants, L. Rodionov, Danila Radin","doi":"10.1109/GFPS.2018.8472398","DOIUrl":"https://doi.org/10.1109/GFPS.2018.8472398","url":null,"abstract":"This paper demonstrates that a tunable Helmholtz resonator (HR) can exist in a gear pump as a broadband absorber. It is common to encounter a problem of the pulsating pressure of working fluid in current hydraulic systems. This pulsation load negatively affects the durability of all elements of the system. Hence the unregulated HR is narrowband silencer, which is not effective over the entire frequency range. Thus it is necessary to design an adaptive HR, which changes its cavity volume so that the natural frequency of resonator corresponds with the excitation frequency. Designing this device requires a lot of calculation. Therefore, the main purpose of the article is creating an automatic system for calculating a tunable resonator. The automatic system for calculating the tuned resonator is created in the software package Microsoft Excel. In the process of creating the system, the existing method of design calculation was made more accurate and a methodology for calculating the absorber’s efficiency was developed. The result of this work is a fully automatic system for calculating a tunable resonator, which can significantly reduce the time, and hence the design cost of this unit. Finally, the adequacy of used methods was confirmed.","PeriodicalId":273799,"journal":{"name":"2018 Global Fluid Power Society PhD Symposium (GFPS)","volume":"61 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123511298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.1109/GFPS.2018.8472380
Beichen Ding, A. Plummer, Pejman Iravani
In the Iegged locomotion research area, it is known that efficient running or hopping in either animals or Iegged robots requires leg actuator compliance. Springy legs interacting with body mass gives a natural hopping/running frequency. Servo-hydraulics is highly suitable for robot leg actuation due to its high power density and fast response. In this paper, we investigate using a hydraulic accumulator connected to a hydraulic cylinder to provide both actuation and the required leg compliance. This approach is experimentally applied to a bipedal hopping robot, and closed loop leg position control is implemented. A non-linear simulation model is used to explain the main findings from the experimental results. The effect of friction in this type of compliant hydraulic actuator is found to be very significant. An error-time factor is introduced to enable an understanding of the friction effect and aids component selection for this application.
{"title":"A Study of a Compliant Hydraulic Actuator for Running Robots","authors":"Beichen Ding, A. Plummer, Pejman Iravani","doi":"10.1109/GFPS.2018.8472380","DOIUrl":"https://doi.org/10.1109/GFPS.2018.8472380","url":null,"abstract":"In the Iegged locomotion research area, it is known that efficient running or hopping in either animals or Iegged robots requires leg actuator compliance. Springy legs interacting with body mass gives a natural hopping/running frequency. Servo-hydraulics is highly suitable for robot leg actuation due to its high power density and fast response. In this paper, we investigate using a hydraulic accumulator connected to a hydraulic cylinder to provide both actuation and the required leg compliance. This approach is experimentally applied to a bipedal hopping robot, and closed loop leg position control is implemented. A non-linear simulation model is used to explain the main findings from the experimental results. The effect of friction in this type of compliant hydraulic actuator is found to be very significant. An error-time factor is introduced to enable an understanding of the friction effect and aids component selection for this application.","PeriodicalId":273799,"journal":{"name":"2018 Global Fluid Power Society PhD Symposium (GFPS)","volume":"253 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125783428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-07-01DOI: 10.1109/GFPS.2018.8472366
N. Pedersen, P. Johansen, T. Andersen
Successful deployment of the digital displacement machine (DDM) as the solution for futurefluid power pump and motor units, demands control strategies and dynamical analysis methods for the technology. For a relatively low speed operated DDM with a relatively low number of cylinders, a partial stroke operation strategy is considered a favorable choice in the attempt of obtaining a smooth response and accurate tracking control. In partial stroke operation, the energy efficiency and severity of flow and pressure spikes are highly dependent on the flow and pressure levels when the on-off valves are opened and closed. A promising control strategy is therefore model predictive control (MPC), enablingthe control objective to be a trade-off between tracking performance and energy efficiency. This paper presents a MPC strategy for a partial stroke operated digital displacement motor, controlling the pressure in a simplified load system. Since the discrete MPC model is based on discrete approximations of the non-smooth machine dynamics, an analysis study is made on the applicability of the approximation. The control strategy is validated by simulation in a non-linear model and tested under different importance weights of set-point tracking relative to energy efficiency.
{"title":"Model Predictive Control and Discrete Analysis of Partial Stroke Operated Digital Displacement Unit","authors":"N. Pedersen, P. Johansen, T. Andersen","doi":"10.1109/GFPS.2018.8472366","DOIUrl":"https://doi.org/10.1109/GFPS.2018.8472366","url":null,"abstract":"Successful deployment of the digital displacement machine (DDM) as the solution for futurefluid power pump and motor units, demands control strategies and dynamical analysis methods for the technology. For a relatively low speed operated DDM with a relatively low number of cylinders, a partial stroke operation strategy is considered a favorable choice in the attempt of obtaining a smooth response and accurate tracking control. In partial stroke operation, the energy efficiency and severity of flow and pressure spikes are highly dependent on the flow and pressure levels when the on-off valves are opened and closed. A promising control strategy is therefore model predictive control (MPC), enablingthe control objective to be a trade-off between tracking performance and energy efficiency. This paper presents a MPC strategy for a partial stroke operated digital displacement motor, controlling the pressure in a simplified load system. Since the discrete MPC model is based on discrete approximations of the non-smooth machine dynamics, an analysis study is made on the applicability of the approximation. The control strategy is validated by simulation in a non-linear model and tested under different importance weights of set-point tracking relative to energy efficiency.","PeriodicalId":273799,"journal":{"name":"2018 Global Fluid Power Society PhD Symposium (GFPS)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124300966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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