This paper reviews the state of the art of directly driven proportional directional hydraulic spool valves, which are widely used hydraulic components in the industrial and transportation sectors. First, the construction and performance of commercially available units are discussed, together with simple models of the main characteristics. The review of published research focuses on two key areas: investigations that analyze and optimize valves from a fluid dynamic point of view, and then studies on spool position control systems. Mathematical modeling is a very active area of research, including computational fluid dynamics (CFD) for spool geometry optimization, and dynamic spool actuation and motion modeling to inform controller design. Drawbacks and advantages of new designs and concepts are described in the paper.

References

1.
Plummer
,
A.
,
2016
, “
Electrohydraulic Servovalves—Past, Present, and Future
,”
Tenth International Fluid Power Conference
, pp.
405
424
.
2.
Tamburrano
,
P.
,
Plummer
,
A. R.
,
Distaso
,
E.
, and
Amirante
,
R.
,
2018
, “
A Review of Electro-Hydraulic Servovalve Research and Development
,”
Int. J. Fluid Power
(in press).
3.
Hunt
,
T.
, and
Vaughan
,
N.
,
1996
,
The Hydraulic Handbook
, 9th ed.,
Elsevier
, Oxford, UK.
4.
Amirante
,
R.
,
Moscatelli
,
P. G.
, and
Catalano
,
L. A.
,
2007
, “
Evaluation of the Flow Forces on a Direct (Single Stage) Proportional Valve by Means of a Computational Fluid Dynamic Analysis
,”
Energy Convers. Manage.
,
48
(
3
), pp.
942
953
.
5.
Majdič
,
F.
,
Pezdirnik
,
J.
, and
Kalin
,
M.
,
2011
, “
Experimental Validation of the Lifetime Performance of a Proportional 4/3 Hydraulic Valve Operating in Water
,”
Tribol. Int.
,
44
(
12
), pp.
2013
2021
.
6.
Majdic
,
F.
,
Pezdirnik
,
J.
, and
Kalin
,
M.
,
2010
, “
Lifetime Test of New Water Hydraulic Proportional Directional Control Valve
,” Seventh
International Fluid Power Conference
, pp.
1
16
.
7.
Suzuki
,
K.
,
Akazawa
,
S.
, and
Nakao
,
Y.
,
2012
, “
Development of Cam-Drive Type Proportional Valve for Water Hydraulics
,”
Int. J. Autom. Technol.
,
6
(
4
), pp.
450
456
.
8.
Koskinen
,
K. T.
, and
Vilenius
,
M. J.
,
2000
, “
Steady State and Dynamic Characteristics of Water Hydraulic Proportional Ceramic Spool Valve
,”
Int. J. Fluid Power
,
1
(
1
), pp.
5
15
.
9.
Majdič
,
F.
,
Velkavrh
,
I.
, and
Kalin
,
M.
,
2013
, “
Improving the Performance of a Proportional 4/3 Water-Hydraulic Valve by Using a Diamond-Like-Carbon Coating
,”
Wear
,
297
(
1–2
), pp.
1016
1024
.
10.
Amirante
,
R.
,
Distaso
,
E.
, and
Tamburrano
,
P.
,
2014
, “
Experimental and Numerical Analysis of Cavitation in Hydraulic Proportional Directional Valves
,”
Energy Convers. Manage.
,
87
, pp. 208–219.
11.
Amirante
,
R.
,
Catalano
,
L. A.
,
Poloni
,
C.
, and
Tamburrano
,
P.
,
2014
, “
Fluid-Dynamic Design Optimization of Hydraulic Proportional Directional Valves
,”
Eng. Optim.
,
46
(
10
), pp. 1295–1314.
12.
Blackburn
,
J. F.
,
Reethof
,
G.
, and
Shearer
,
J. L.
,
1960
,
Fluid Power Control
,
The MIT Press and Wiley
, New York.
13.
Merritt
,
H.
,
1967
,
Hydraulic Control Systems
,
Wiley
, Hoboken, NJ.
14.
Eryilmaz
,
B.
, and
Wilson
,
B. H.
,
2006
, “
Unified Modeling and Analysis of a Proportional Valve
,”
J. Franklin Inst.
,
343
(
1
), pp.
48
68
.
15.
Amirante
,
R.
,
Lippolis
,
A.
, and
Tamburrano
,
P.
,
2013
, “
Theoretical and Experimental Analysis of a Coupled System Proportional Control Valve and Hydraulic Cylinder
,”
Univers. J. Eng. Sci.
,
1
(
2
), pp.
45
56
.
16.
Jiang
,
W.
,
Huang
,
X.
,
Gao
,
Q.
, and
Peng
,
A.
,
2010
, “
The Modeling and Parameter Identification of the Hydraulic Proportional Valve
,”
2010 International Conference on Computer, Mechatronics, Control and Electronic Engineering (CMCE 2010)
, Vol.
3
, pp.
482
485
.
17.
Zhu
,
Y.
, and
Jin
,
B.
,
2016
, “
Analysis and Modeling of a Proportional Directional Valve With Nonlinear Solenoid
,”
J. Braz. Soc. Mech. Sci. Eng.
,
38
(
2
), pp.
507
514
.
18.
Menshawy
,
T. M.
,
Moghazy
,
M. A.
, and
Lotfy
,
A. H.
,
2009
, “
Investigation of Dynamic Performance of an Electro-Hydraulic Proportional System
,”
13th International Conference on Aerospace Sciences and Aviation Technology
, pp.
1
18
.
19.
Parr
,
A.
,
2011
,
Hydraulics and Pneumatics: A Technician's and Engineer's Guide
, 3rd ed.,
Butterworth-Heinemann
,
Oxford, UK
.
20.
Jin
,
B.
,
Zhu
,
Y.
,
Li
,
W.
,
Zhang
,
D.
,
Zhang
,
L.
, and
Chen
,
F.
,
2014
, “
A Differential Control Method for the Proportional Directional Valve
,”
J. Zhejiang Univ. Sci. C
,
15
(
10
), pp.
892
902
.
21.
Amirante
,
R.
,
Innone
,
A.
, and
Catalano
,
L. A.
,
2008
, “
Boosted PWM Open Loop Control of Hydraulic Proportional Valves
,”
Energy Convers. Manage.
,
49
(
8
), pp.
2225
2236
.
22.
Elmer
,
K. F.
, and
Gentle
,
C. R.
,
2001
, “
A Parsimonious Model for the Proportional Control Valve
,”
Proc. Inst. Mech. Eng., Part C
,
215
(
11
), pp.
1357
1363
.
23.
Amirante
,
R.
,
Distaso
,
E.
, and
Tamburrano
,
P.
,
2016
, “
Sliding Spool Design for Reducing the Actuation Forces in Direct Operated Proportional Directional Valves: Experimental Validation
,”
Energy Convers. Manage.
,
119
, pp. 399–410.
24.
Simic
,
M.
, and
Herakovic
,
N.
,
2015
, “
Reduction of the Flow Forces in a Small Hydraulic Seat Valve as Alternative Approach to Improve the Valve Characteristics
,”
Energy Convers. Manage.
,
89
, pp.
708
718
.
25.
Herakovič
,
N.
,
2015
, “
CFD Simulation of Flow Force Reduction in Hydraulic Valves
,”
Teh. Vjesn. Tech. Gaz.
,
22
(
2
), pp.
453
463
.
26.
Yuan
,
Q.
, and
Li
,
P. Y.
,
2002
, “
An Experimental Study on the Use of Unstable Electrohydraulic Valves for Control
,”
American Control Conference
, Vol.
6
, pp.
4843
4848
.
27.
Hong
,
S. H.
, and
Kim
,
K. W.
,
2016
, “
A New Type Groove for Hydraulic Spool Valve
,”
Tribol. Int.
,
103
, pp.
629
640
.
28.
Borghi
,
M.
,
Milani
,
M.
, and
Paoluzzi
,
R.
,
2005
, “
Influence of Notch Shape and Number of Notches on the Metering Characteristics of Hydraulic Spool Valves
,”
Int. J. Fluid Power
,
6
(
2
), pp.
5
18
.
29.
Valdés
,
J. R.
,
Rodríguez
,
J. M.
,
Monge
,
R.
,
Peña
,
J. C.
, and
Pütz
,
T.
,
2014
, “
Numerical Simulation and Experimental Validation of the Cavitating Flow Through a Ball Check Valve
,”
Energy Convers. Manage.
,
78
, pp.
776
786
.
30.
Martelli
,
M.
,
Gessi
,
S.
,
Massarotti
,
G. P.
,
Marani
,
P.
, and
Zarotti
,
L. G.
,
2017
, “
On Peculiar Flow Characteristics in Hydraulic Orifices
,”
ASME
Paper No. FPMC2017-4313.
31.
Ebrahimi, B., He, G., Tang, Y., Franchek, M., Liu, D., Pickett, J., Springett, F., and Franklin, D.,
2017
, “
Characterization of High-Pressure Cavitating Flow Through a Thick Orifice Plate in a Pipe of Constant Cross Section
,”
Int. J. Therm. Sci.
,
114
, pp.
229
240
.
32.
Amirante
,
R.
,
Andrea Catalano
,
L.
, and
Tamburrano
,
P.
,
2014
, “
The Importance of a Full 3D Fluid Dynamic Analysis to Evaluate the Flow Forces in a Hydraulic Directional Proportional Valve
,”
Eng. Comput.
,
31
(
5
), pp.
898
922
.
33.
Lisowski
,
E.
,
Czyzycki
,
W.
, and
Rajda
,
J.
,
2013
, “
Three Dimensional CFD Analysis and Experimental Test of Flow Force Acting on the Spool of Solenoid Operated Directional Control Valve
,”
Energy Convers. Manag.
,
70
, pp.
220
229
.
34.
Jackson
,
R. S.
,
Belger
,
M. M.
,
Cassaidy
,
K. J.
, and
Kokemoor
,
A. R.
,
2017
, “
CFD Simulation and Experimental Investigation of Steady State Flow Force Reduction in a Hydraulic Spool Valve With Machined Back Angles
,”
ASME
Paper No. FPMC2017-4323.
35.
ANSYS
,
2009
, “
ANSYS Fluent 12.0 Theory Guide
,” ANSYS, Inc. Canonsburg, PA.
36.
Milani
,
M.
,
Montorsi
,
L.
, and
Paltrinieri
,
F.
,
2012
, “
Multidimensional Design of Hydraulic Components and Systems
,”
Applied Computational Fluid Dynamics
, DISMI – University of Modena and Reggio Emilia, Italy.
37.
Borghi
,
M.
,
Milani
,
M.
, and
Paoluzzi
,
R.
,
2000
, “
Stationary Axial Flow Force Analysis on Compensated Spool Valves
,”
Int. J. Fluid Power
,
1
(
1
), pp.
17
25
.
38.
Amirante
,
R.
,
Vescovo
,
G. D.
, and
Lippolis
,
A.
,
2006
, “
Flow Forces Analysis of an Open Center Hydraulic Directional Control Valve Sliding Spool
,”
Energy Convers. Manage.
,
47
(
1
), pp.
114
131
.
39.
Amirante
,
R.
,
Del Vescovo
,
G.
, and
Lippolis
,
A.
,
2006
, “
Evaluation of the Flow Forces on an Open Centre Directional Control Valve by Means of a Computational Fluid Dynamic Analysis
,”
Energy Convers. Manage.
,
47
(
13–14
), pp.
1748
1760
.
40.
Baudry
,
X.
, and
Mare
,
J. C.
,
2000
, “
Linking CFD and Lumped Parameters Analysis for the Design of Flow Compensated Spool Valves
,”
First FPNI-PhD Symposium Hamburg
, pp.
249
58
.
41.
Del Vescovo
,
G.
, and
Lippolis
,
A.
,
2003
, “
CFD Analysis of Flow Forces on Spool Valves
,”
First International Conference on Computational Methods in Fluid Power Technology
, Melbourne, Australia, Nov. 26–28.
42.
Del Vescovo
,
G.
, and
Lippolis
,
A.
,
2003
, “
Three-Dimensional Analysis of Flow Forces on Directional Control Valves
,”
Int. J. Fluid Power
,
4
(
2
), pp.
15
24
.
43.
Valdés
,
J. R.
,
Miana
,
M. J.
,
Núñez
,
J. L.
, and
Pütz
,
T.
,
2008
, “
Reduced Order Model for Estimation of Fluid Flow and Flow Forces in Hydraulic Proportional Valves
,”
Energy Convers. Manage.
,
49
(
6
), pp.
1517
1529
.
44.
Posa
,
A.
,
Oresta
,
P.
, and
Lippolis
,
A.
,
2013
, “
Analysis of a Directional Hydraulic Valve by a Direct Numerical Simulation Using an Immersed-Boundary Method
,”
Energy Convers. Manage.
,
65
, pp.
497
506
.
45.
Beaudoin
,
M.
, and
Jasak
,
H.
,
2008
, “
Development of a Generalized Grid Interface for Turbomachinery Simulations With OpenFOAM
,”
Open Source CFD International Conference
, Berlin, Germany, Dec. 4–5.http://powerlab.fsb.hr/ped/kturbo/OpenFOAM/Berlin2008/Papers/OSCIC-08_BeaudoinMartinJasakHrvoje.pdf
46.
Ye
,
Y.
,
Yin
,
C. B.
,
Li
,
X. D.
,
Zhou
,
W. J.
, and
Yuan
,
F. F.
,
2014
, “
Effects of Groove Shape of Notch on the Flow Characteristics of Spool Valve
,”
Energy Convers. Manage.
,
86
, pp.
1091
1101
.
47.
Frosina
,
E.
,
Senatore
,
A.
,
Buonoa
,
D.
,
Pavanetto
,
M.
, and
Olivetti
,
M.
,
2015
, “
3D CFD Transient Analysis of the Forces Acting on the Spool of a Directional Valve
,”
Energy Procedia
,
81
, pp.
1090
1101
.
48.
Lisowski
,
E.
, and
Filo
,
G.
,
2017
, “
Analysis of a Proportional Control Valve Flow Coefficient With the Usage of a CFD Method
,”
Flow Meas. Instrum.
,
53
, pp.
269
278
.
49.
Lisowski
,
E.
, and
Rajda
,
J.
,
2013
, “
CFD Analysis of Pressure Loss During Flow by Hydraulic Directional Control Valve Constructed From Logic Valves
,”
Energy Convers. Manage.
,
65
, pp.
285
291
.
50.
Lisowski
,
E.
, and
Filo
,
G.
,
2016
, “
CFD Analysis of the Characteristics of a Proportional Flow Control Valve With an Innovative Opening Shape
,”
Energy Convers. Manage.
,
123
, pp.
15
28
.
51.
Lisowski
,
E.
,
Filo
,
G.
, and
Rajda
,
J.
,
2015
, “
Pressure Compensation Using Flow Forces in a Multi-Section Proportional Directional Control Valve
,”
Energy Convers. Manage.
,
103
, pp.
1052
1064
.
52.
Lisowski
,
E.
,
Filo
,
G.
, and
Rajda
,
J.
,
2018
, “
Analysis of Flow Forces in the Initial Phase of Throttle Gap Opening in a Proportional Control Valve
,”
Flow Meas. Instrum.
,
59
, pp.
157
167
.
53.
Ansaloni
,
G.
,
Marani
,
P.
, and
Paoluzzi
,
R.
,
2008
, “
Proportional Valve With Axial Flow and Rotational Metering
,”
Proc. JFPS Int. Symp. Fluid Power
,
2008
(
7–3
), pp.
591
596
.
54.
Wang
,
H.
,
Gong
,
G.
,
Zhou
,
H.
, and
Wang
,
W.
,
2016
, “
Steady Flow Torques in a Servo Motor Operated Rotary Directional Control Valve
,”
Energy Convers. Manage.
,
112
, pp. 1–10.
55.
Okhotnikov
,
I.
,
Noroozi
,
S.
,
Sewell
,
P.
, and
Godfrey
,
P.
,
2017
, “
Evaluation of Steady Flow Torques and Pressure losses in a Rotary Flow Control Valve by Means of Computational Fluid Dynamics
,”
Int. J. Heat Fluid Flow
,
64
, pp. 89–102.
56.
Zhu
,
M.
,
Zhao
,
S.
,
Li
,
J.
, and
Dong
,
P.
,
2018
, “
Computational Fluid Dynamics and Experimental Analysis on Flow Rate and Torques of a Servo Direct Drive Rotary Control Valve
,”
Proc. Inst. Mech. Eng., Part C
, (epub).
57.
Herakovič
,
N.
,
2009
, “
Flow-Force Analysis in a Hydraulic Sliding-Spool Valve
,”
Strojarstvo
,
51
(
6
), pp.
555
564
.
58.
Tørdal, S. S., Klausen, A., and Bak, M. K., 2015, “
Experimental System Identification and Black Box Modeling of Hydraulic Directional Control Valve
,”
Model., Identif. Control
,
35
(4), pp. 225–235.
59.
Bayat
,
F.
,
Fadaie Tehrani
,
A.
, and
Danesh
,
M.
,
2011
, “
Static and Dynamic Simulation of a Proportional Control Valve Using ANSYS/Emag
,”
2011 IEEE International Conference on Mechatronics (ICM 2011)
, pp.
581
584
.
60.
Buono
,
D.
,
Senatore
,
A.
,
Frosina
,
M.
,
Gehlhoff
,
W.
, and
Costin
,
I. I.
,
2016
, “
Simulation and Experimental Investigations of a Digital High Speed Close Loop Proportional Directional Valve Using a Solenoid Technology
,”
ASME
Paper No. FPMC2016-1748.
61.
Ferrari
,
A.
,
Pizzo
,
P.
, and
Rundo
,
M.
,
2017
, “
Modelling and Experimental Studies on a Proportional Valve Using an Innovative Dynamic Flow-Rate Measurement in Fluid Power Systems
,”
Proc. Inst. Mech. Eng., Part C
,
232
(13), pp. 2404–2418.
62.
Vaughan
,
N. D.
, and
Gamble
,
J. B.
,
1996
, “
The Modeling and Simulation of a Proportional Solenoid Valve
,”
ASME Trans. Soc. Mech. Eng. J. Dyn. Syst. Meas. Control
,
118
(
1
), pp.
120
125
.
63.
Cristofori
,
D.
, and
Vacca
,
A.
,
2012
, “
The Modeling of Electrohydraulic Proportional Valves
,”
ASME J. Dyn. Syst. Meas. Control
,
134
(
2
), p.
21008
.
64.
Bu
,
F.
, and
Yao
,
B.
,
2000
, “
Nonlinear Adaptive Robust Control of Hydraulic Actuators Regulated by Proportional Directional Control Valves With Deadband and Nonlinear Flow Gains
,”
American Control Conference
, Vol.
6
, pp.
4129
4133
.
65.
Valdiero
,
A. C.
,
Bavaresco
,
D.
, and
Andrighetto
,
P. L.
,
2008
, “
Experimental Identification of the Dead Zone in Proportional Directional Pneumatic Valves
,”
Int. J. Fluid Power
,
9
(
1
), pp.
27
33
.
66.
Valdiero
,
A. C.
,
Guenther
,
R.
, and
De Negri
,
V. J.
,
2005
, “
New Methodology for Identification of the Dead Zone in Proportional Directional Hydraulic Valves
,”
18th International Congress of Mechanical Engineering
, Ouro Preto, Brazil, Nov. 6–11.https://www.researchgate.net/publication/241424398_New_methodology_for_identification_of_the_dead_zone_in_proportional_directional_hydraulic_valves
67.
Gamble
,
J. B.
, and
Vaughan
,
N. D.
,
1996
, “
Comparison of Sliding Mode Control With State Feedback and PID Control Applied to a Proportional Solenoid Valve
,”
ASME J. Dyn. Syst. Meas. Control
,
118
(
3
), pp.
434
438
.
68.
Liu
,
Y. F.
,
Dai
,
Z. K.
,
Xu
,
X. Y.
, and
Tian
,
L.
,
2011
, “
Multi-Domain Modeling and Simulation of Proportional Solenoid Valve
,”
J. Cent. South Univ. Technol.
,
18
(
5
), pp.
1589
1594
.
69.
Kong
,
X.
, and
Wang
,
H.
,
2010
, “
A Spool Displacement Control System of Proportional Valve Based on Digital Observer
,”
Key Eng. Mater.
,
455
, pp.
110
115
.
70.
Bu
,
F.
, and
Yao
,
B.
,
2000
, “
Performance Improvement of Proportional Directional Control Valves: Methods and Experiments
,” ASME Dynamic Systems and Control Division Conference.
71.
Jin
,
B.
,
Zhu
,
Y. G.
, and
Li
,
W.
,
2013
, “
PID Parameters Tuning of Proportional Directional Valve Based on Multiple Orthogonal Experiments Method: Method and Experiments
,”
Appl. Mech. Mater.
,
325
, pp.
1166
1169
.
72.
Renn
,
J. C.
, and
Tsai
,
C.
,
2005
, “
Development of an Unconventional Electro-Hydraulic Proportional Valve With Fuzzy-Logic Controller for Hydraulic Presses
,”
Int. J. Adv. Manuf. Technol.
,
26
(
1–2
), pp.
10
16
.
73.
Wang
,
X.
,
2010
, “
Fuzzy-PID Control in Electro-Hydraulic Proportional Valve System
,”
2010 IEEE 11th International Conference on Computer-Aided Industrial Design and Conceptual Design (CAID and CD'2010)
, Vol.
2
, pp.
1454
1457
.
74.
Lee
,
I. Y.
,
Oh
,
D. H.
,
Ji
,
S. W.
, and
Yun
,
S. N.
,
2015
, “
Control of an Overlap-Type Proportional Directional Control Valve Using Input Shaping Filter
,”
Mechatronics
,
29
, pp.
87
95
.
75.
Braun
,
T.
,
Reuter
,
J.
, and
Rudolph
,
J.
,
2016
, “
Position Observation for Proportional Solenoid Valves by Signal Injection
,”
IFAC-PapersOnLine
,
49
(
21
), pp.
74
79
.
76.
Acuña-Bravo
,
W.
,
Canuto
,
E.
,
Agostani
,
M.
, and
Bonadei
,
M.
,
2017
, “
Proportional Electro-Hydraulic Valves: An Embedded Model Control Solution
,”
Control Eng. Pract.
,
62
, pp.
22
35
.
77.
Yudell
,
A. C.
, and
Van De Ven
,
J. D.
,
2015
, “
Predicting Solenoid Valve Spool Displacement Through Current Analysis
,”
Int. J. Fluid Power
,
16
(
3
), pp.
133
140
.
78.
Hui Fang
,
J.
,
Guo
,
F.
,
Chen
,
Z.
, and
Hua Wei
,
J.
,
2017
, “
Improved Sliding-Mode Control for Servo-Solenoid Valve With Novel Switching Surface Under Acceleration and Jerk Constraints
,”
Mechatronics
,
43
, pp.
66
75
.
79.
Reinert
,
D.
,
Gorgs
,
K. J.
, and
Kimura
,
T.
,
2006
, “
Safety Studies on Hydraulic Proportional Valves With Electrical Position Feedback
,”
Int. J. Occup. Saf. Ergon.
,
12
(
1
), pp.
105
115
.
80.
Sell
,
N. P.
,
Johnston
,
D. N.
,
Plummer
,
A. R.
, and
Kudzma
,
S.
,
2013
, “
Control of a Fast Switching Valve for Digital Hydraulics
,”
13th Scandinavian International Conference on Fluid Power
, pp.
497
503
.
81.
Sell
,
N. P.
,
Johnston
,
N.
,
Plummer
,
A. R.
, and
Kudzma
,
S.
,
2015
, “
Development of a Position Controlled Digital Hydraulic Valve
,”
ASME
Paper No. FPMC2015-9514.
82.
Raghuraman
,
D. R. S.
, and
Kumar
,
S. S.
,
2016
, “
Digital Hydraulic Valves—A Brief Review
,”
J. Chem. Pharm. Sci.
,
974
, pp. 68–72.
83.
Linjama
,
M.
,
Paloniitty
,
M.
,
Tiainen
,
L.
, and
Huhtala
,
K.
,
2015
, “
Mechatronic Design of Digital Hydraulic Micro Valve Package
,”
Procedia Eng.
,
106
, pp.
97
107
.
84.
Paloniitty
,
M.
,
Linjama
,
M.
, and
Huhtala
,
K.
,
2015
, “
Equal Coded Digital Hydraulic Valve System—Improving Tracking Control With Pulse Frequency Modulation
,”
Procedia Eng.
,
106
, pp.
83
91
.
85.
Linjama
,
M.
, and
Huhtala
,
K.
,
2010
, “
Digital Hydraulic Power Management System—Towards Lossless Hydraulics
,”
Third Workshop on Digital Fluid Power
, Tampere, Finland, Oct. 13–14, pp.
5
22
.
86.
Linjama
,
M.
,
Laamanen
,
A.
, and
Vilenius
,
M.
,
2007
, “
On the Pressure Peak Minimization in Digital Hydraulics
,”
Int. J. Fluid Power
,
11
(
3
), pp.
2
16
.
87.
Huova
,
M.
,
Karvonen
,
M.
,
Ahola
,
V.
,
Linjama
,
M.
, and
Vilenius
,
M.
,
2010
, “
Energy Efficient Control of Multiactuator Digital Hydraulic Mobile Machine
,”
Seventh International Fluid Power Conference
, pp.
1
12
.
88.
Linjama
,
M.
,
2011
, “
Digital Fluid Power—State of the Art
,”
12th Scandinavian International Conference on Fluid Power
, Tampere, Finland, May 18–20, p.
331
.
89.
Linjama
,
M.
,
Laamanen
,
A.
, and
Vilenius
,
M.
,
2003
, “
Is It Time for Digital Hydraulics?
,”
Eighth Scandinavian International Conference on Fluid Power (SICFP '03)
, Vol.
1
, pp.
347
366
.
You do not currently have access to this content.