Control and Performance Analysis of a Digital Direct Hydraulic Cylinder Drive
DOI:
https://doi.org/10.13052/ijfp1439-9776.2032Keywords:
Digital Displacement Machines, Hydraulics, Fluid Power, Direct Drive, Control, Energy EfficientAbstract
This paper concerns control of a digital direct hydraulic cylinder drive (D-DHCD) and is a novel concept with the potential to become the future solution for energy efficient hydraulic drives. The concept relies on direct control of a differential cylinder by a single hydraulic pump/motor unit connected to each cylinder inlet/outlet. The pump/motor unit in this research uses the digital displacement technology and comprises of numerous individually digital controlled pressure chambers, such that the ratio of active (motoring, pumping or idling) chambers determines the machine power throughput. This feature reduces energy losses to a minimum, since the inactive (idling) chambers has very low losses. A single DDM may provide individually load control for several cylinders without excessive throttling due to various load sizes. Successful implementation of the concept relies on proper control of the DDM, which demands a dynamical model that allows for system analysis and controller synthesis. This is a challenging task, due to the highly non-smooth machine behavior, comprising both non-linear continuous and discrete elements. This paper presents the first feedback control strategy for a D-DHCD concept, based on a discrete dynamical approximation and investigates the control performance in a mathematical simulation model representing the physical system.
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References
Andersen, T.O. and Hansen, M.R., 2003. Fluid Power Systems – Modelling
and Analysis. 2nd edition. AAU.
Armstrong, B.S.R. and Yuan, Q., 2006. Multi-level control of hydraulic
gerotor motors and pumps. Proceedings of the American Control
Conference, Minnesota, USA.
Dengler, P., Geimer, M., and von Dombrowski, R., 2012. Deterministic control
strategy for a hybrid hydraulic system with intermediate pressure
line. Proceedings of the Fluid Power and Motion Control (FPMC),
Bath, UK.
Dengler, P., Groh, J., and Geimer, M., 2011. Valve control concepts in
a constant pressure system with an intermediate pressure line. 21st
International Conference on Hydraulics and Pneumatics, Ostrava,
Czech Republic.
Ehsan, M., Rampen, W., and Salter, S., 1997. Modeling of digitaldisplacement
pump-motors and their application as hydraulic drives
for nonuniform loads. Asme. J. Dyn. Sys., Meas., Control.
Heikkila, M. and Linjama, M., 2013. Displacement control of a mobile crane
using digital hydraulic power management system. Mechatronics,
volume 23, issue 4, pages 452–461.
Heybroek, K., Larsson, J., and Palmberg, J.O., 2006. Open circuit solution
for pump controlled actuators. Proceedings of the 4th FPNI-PHD
Symposium. Sarasota.
Heybroek, K., et al., 2008. Evaluating a pump controlled open circuit solution.
Proceedings of the 51th International Exposition for Power
Transmission, Nevada, USA.
Ivantysynova, M. and Rahmfeld, R., 1998. Energy saving hydraulic actuators
for mobile machinery. 1st Bratislavian Fluid Power Symposium.
Johansen, P., et al., 2017. Discrete linear time invariant analysis of digital
fluid power pump flow control. Journal of Dynamic Systems, Measurement
and Control, Transactions of the ASME, vol. 139, no. 10,
Johansen, P., et al., 2015. Delta-sigma modulated displacement of a digital
fluid power pump. The 7th Workshop on Digital Fluid Power, Linz,
Austria.
Heikkilä, M. and Linjama, M. 2013. Displacement control of a mobile crane
using a digital hydraulic power management system. Mechatronics,
(4a), 452–461.
Nielsen, B., 2005. Controller Development for a Separate Meter-in Separate
Meter-out Fluid Power Valve for Mobile Applications. Thesis (PhD).
Department of Energy Technology, Aalborg University.
Payne, G.S., et al., 2005. Potential of digital displacement hydraulics for
wave energy conversion. In Proc. of the 6th European Wave and Tidal
Energy Conference, Glasgow UK.
Pedersen, N.H., Johansen, P., and Andersen, T.O., 2016. Lqr feedback control
development for wind turbines featuring a digital fluid power transmission
system. Proceedings of the 9th FPNI Ph.D. Symposium on Fluid
Power. American Society of Mechanical Engineers.
Pedersen, N.H., Johansen, P., and Andersen, T.O., 2017a. Optimal control of
a wind turbine with digital fluid power transmission. Nonlinear Dyn.
Pedersen, N.H., Johansen, P., and Andersen, T.O., 2017b. Event-driven control
of a speed varying digital displacement machine. Proceedings
of the 2017 BATH/ASME Symposium on Fluid Power and Motion
Control.
Pedersen, N.H., Johansen, P., and Andersen, T.O., 2018. Feedback control of
multi-level pulsedensity modulated digital displacement transmission.
IEEE/ASME Transaction on Mecatronics, vol. x, no. x.
Rampen, W., 2010. The development of digital displacement technology.
In Proceedings of BATH/ASME FPMC Symposium.
Schmidt, L., et al., 2017. Position control of an over-actuated direct hydraulic
cylinder drive. Control Engineering Practice 64, 1–14.
Schmidt, L., et al., 2015. Speed-variable switched differential pump system
for a direct operation of hydraulic cylinders. Proceedings of
ASME/BATH Symposium on Fluid Power & Motion Control, Chicago,
Illinois USA.
Sniegucki, M., Gottfried, M., and Klingauf, U., 2013. Optimal control
of digital hydraulic drives using mixed-integer quadratic programming.
Proceedings of the 9th IFAC Symposium on Nonlinear Control
Systems.
Song, X., 2008. Modeling and active vehicle suspension system with application
of digital displacement pump motor. Proceedings of the ASME
International Design Engineering Technical Conferences &
Computers and Information in Engineering Conference, New York,
USA.
