Optimal Control Theory Applied to Pressure-Controlled Axial Piston Pump Design

1990 ◽  
Vol 112 (3) ◽  
pp. 475-481 ◽  
Author(s):  
S. J. Lin ◽  
A. Akers
Keyword(s):  
Optimal Control ◽  
Control Theory ◽  
Optimal Control Theory ◽  
Control Valve ◽  
Open Loop ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Response Curves ◽  
Pump Design ◽  
Axial Piston

This work presents a study of the applicability of optimal control theory to the design of a pressure regulator by use of an axial piston pump with a two-stage electrohydraulic servovalve. The control valve has been modeled and an optimal control law has been formulated. The time response curves due to a step input in flow rate to the pump have been obtained for the open loop and the for the optimal control system. An examination of the results has shown that the performance, in terms of pressure peaks and frequency during recovery to the flow disturbance, is significantly improved over that obtained when a single-stage valve is used.

Optimal Control Theory Applied to a Pump With Single-Stage Electrohydraulic Servovalve

1988 ◽  
Vol 110 (2) ◽  
pp. 120-125 ◽  
Author(s):  
A. Akers ◽  
S. J. Lin
Keyword(s):  
Optimal Control ◽  
Control Theory ◽  
Optimal Control Theory ◽  
System Modeling ◽  
Control Valve ◽  
Open Loop ◽  
Single Stage ◽  
Response Curves ◽  
Electrohydraulic Valve ◽  
Comparison Of The Results

Optimal control theory is applied to the design of a pressure regulator for an axial piston pump and single-stage electrohydraulic valve combination. The control valve has been modeled and an optimal control law has been formulated. The time response curves due to a step input inflow rate and in current input to the servovalve have been obtained for the open loop and for the optimal control system. Comparison of the results has been made with previous work in which the supply valve to the swashplate actuators was not modeled. It is shown that controlled system modeling of the servovalve significantly improves system performance in terms of response frequency and pressure peaks.

A Novel Axial Piston Pump/Motor Principle With Floating Pistons: Design and Testing

2018 ◽  
Author(s):  
Liselott Ericson ◽  
Jonas Forssell
Keyword(s):  
Low Noise ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Pump Design ◽  
Main Challenge ◽  
Piston Seal ◽  
Displacement Angle ◽  
Type Machine ◽  
Expected Benefits ◽  
Axial Piston

This paper presents the first prototype of a novel axial piston pump/motor of slipper type. The pistons are floating in the cylinders and hence the name floating piston pump. The novel pump design fills a gap in the traditional pump design. The pump is made to fit the automobile requirements to use fluid power in a more prominent manner. One of the expected benefits of this design is its simplicity and therefore the machine does not require high manufacturing capabilities. The production cost is expected to be low. The machine is designed with high number of pistons, which leads to a pump/motor with low noise level. The displacement angle is small, 8 degrees, which leads to low piston speeds with its benefits. The main challenge in the design is the piston seal configuration. The seals will both, deform (ovality) and move in a circle relative to the pistons. The paper discusses design considerations and proposes a design. The efficiency measurement of the first prototype is in level of a series produced slipper type machine at its sweet spot.

Adjoint-Based Optimization Procedure for Active Vibration Control of Nonlinear Mechanical Systems

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Carmine M. Pappalardo ◽  
Domenico Guida
Keyword(s):  
Optimal Control ◽  
Control Theory ◽  
Control Problem ◽  
Numerical Solution ◽  
Optimal Control Theory ◽  
Numerical Procedure ◽  
Nonlinear Optimal Control ◽  
Open Loop ◽  
Adjoint Equations ◽  
Loop Control

In this paper, a new computational algorithm for the numerical solution of the adjoint equations for the nonlinear optimal control problem is introduced. To this end, the main features of the optimal control theory are briefly reviewed and effectively employed to derive the adjoint equations for the active control of a mechanical system forced by external excitations. A general nonlinear formulation of the cost functional is assumed, and a feedforward (open-loop) control scheme is considered in the analytical structure of the control architecture. By doing so, the adjoint equations resulting from the optimal control theory enter into the formulation of a nonlinear differential-algebraic two-point boundary value problem, which mathematically describes the solution of the motion control problem under consideration. For the numerical solution of the problem at hand, an adjoint-based control optimization computational procedure is developed in this work to effectively and efficiently compute a nonlinear optimal control policy. A numerical example is provided in the paper to show the principal analytical aspects of the adjoint method. In particular, the feasibility and the effectiveness of the proposed adjoint-based numerical procedure are demonstrated for the reduction of the mechanical vibrations of a nonlinear two degrees-of-freedom dynamical system.

The Shaft Torque of a Tandem Axial-Piston Pump

2006 ◽  
Vol 129 (3) ◽  
pp. 367-371 ◽  
Author(s):  
Noah D. Manring ◽  
Viral S. Mehta ◽  
Frank J. Raab ◽  
Kevin J. Graf
Keyword(s):  
Angular Position ◽  
Single Pulse ◽  
Torque Ripple ◽  
Piston Pump ◽  
Additional Parameter ◽  
Axial Piston Pump ◽  
Pump Design ◽  
Ripple Amplitude ◽  
Shaft Torque ◽  
Axial Piston

The objective of this study is to identify the best indexed position of two rotating groups within a tandem axial-piston pump for attenuating the torque ripple amplitude that is exerted on the shaft. By attenuating the torque ripple characteristics of the pump, other vibration aspects of the machine are also expected to be reduced. In particular, the objectives of this paper are aimed at reducing the noise that is generated by the pump. This paper begins by considering the theoretical torque ripple that is created by the discrete pumping elements of a single rotating group within an axial piston machine. From this analysis, an equation is produced that describes a single pulse for the torque ripple as a function of the average torque and the total number of pistons that are used within the rotating group. By superposing another rotating group on top of the first, and by indexing the angular position of one rotating group relative to the other, a second equation is produced for describing the theoretical torque ripple of a tandem pump design. This equation is also a function of the average shaft torque and the total number of pistons that are used within a single rotating group; however, an additional parameter known as the index angle also appears in this result. This index angle is shown to amplify or attenuate the amplitude of the torque ripple depending upon its value. From these results, it is shown that a proper selection of the index angle can reduce the torque ripple amplitude by as much as 75%.

New Swash Plate Damping Model for Hydraulic Axial-Piston Pump

1999 ◽  
Vol 123 (3) ◽  
pp. 463-470 ◽  
Author(s):  
X. Zhang ◽  
J. Cho ◽  
S. S. Nair ◽  
N. D. Manring
Keyword(s):  
Open Loop ◽  
Operating Conditions ◽  
Reduced Order Model ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Order Model ◽  
Nonlinear Simulation ◽  
Reduced Order ◽  
Swash Plate ◽  
Axial Piston

A new, open-loop, reduced order model is proposed for the swash plate dynamics of an axial piston pump. The difference from previous reduced order models is the modeling of a damping mechanism not reported previously in the literature. An analytical expression for the damping mechanism is derived. The proposed reduced order model is validated by comparing with a complete nonlinear simulation of the pump dynamics over the entire range of operating conditions.

Design and Analysis of a Swashplate Control System for an Asymmetric Axial Piston Pump

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Wei He ◽  
Jia-Hai Huang ◽  
Hui-Min Hao ◽  
Long Quan ◽  
Shuai-xu Ji ◽  
...  
Keyword(s):  
Control System ◽  
Open Loop ◽  
System Dynamic ◽  
Piston Pump ◽  
Design Parameters ◽  
Axial Piston Pump ◽  
Swash Plate ◽  
Design Requirements ◽  
Bode Diagram ◽  
Axial Piston

Abstract Based on the previously developed fixed-displacement asymmetric axial piston pump, a variable displacement asymmetric axial piston pump (VDAAPP) with three independent suction/delivery ports is proposed. A basic linear model of VDAAPP is established to get open-loop bode diagram. Based on open-loop Bode diagram features and design requirements, P-controller is determined for VDAAPP. Then VDAAPP's performance is investigated by advanced modeling environment for performing simulations of engineering systems (AMESim) and automatic dynamic analysis of mechanical systems (ADAMS) joint simulation, and some key design parameters are obtained. Next, a VDAAPP prototype with a maximum displacement of 40 cc/rev is designed and manufactured, ratio of flow rates at ports A, B and T is 1:0.6:0.4. Due to hard limitations of the test bench, the performance only under the conditions of the opposite passive loads is tested. Preliminary test results indicate that VDAAPP prototype works normally and meets the design requirements for flow ratio, and the maximum rise time of the test pressure is about 0.32 s. However, due to special design of VDAAPP valve plate, the swash plate torque severely limits system dynamic response. Therefore, an improved swashplate control system based on asymmetric-valve-controlled asymmetric-piston scheme is presented as well, it is found to be an effective way to suppress the negative impact of swash plate torque on system dynamic performance. This provides a direction for the optimization of the swashplate control system for asymmetric axial piston pumps in the future.

Physical Limitations for the Bandwidth Frequency of a Pressure Controlled, Axial-Piston Pump

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Noah D. Manring ◽  
Viral S. Mehta
Keyword(s):  
Dynamical Behavior ◽  
Control Valve ◽  
Dynamical Property ◽  
Piston Pump ◽  
Closed Form Expression ◽  
Design Parameters ◽  
Axial Piston Pump ◽  
Axial Piston ◽  
Pressure Controlled ◽  
Valve Model

The objectives of this paper are to identify the design parameters that have the greatest impact on the bandwidth frequency of a pressure controlled, axial-piston pump. This study is motivated by the fact that a physical limitation for these machines has been observed in practice, as it has been difficult to increase the bandwidth frequency much beyond 25 Hz. Though much research has been done over the past thirty years to understand the dynamical behavior of these machines, the essential design-characteristics that determine the bandwidth frequency of the pump remain elusive. In part, this is due to the fact that the machine is complex and when coupled with a hydraulic control valve that is disturbed by steady and transient fluid-momentum effects this dynamical property becomes difficult to assess. In order to achieve the objectives of this research, this paper presents the most comprehensive pump-and-valve model of a pressure controlled, axial-piston machine available in the literature to date. The pump model includes the effects of the discrete pumping-elements acting on the swash plate, while the valve model includes both steady and transient fluid-momentum forces. To identify the dominate features of the model, nondimensional analysis is employed and the complexity of the model is subsequently reduced by eliminating negligible terms. Furthermore, a closed-form expression for the bandwidth frequency is employed and perturbation analysis is used to identify the dominant set of parameters that impact the bandwidth frequency of the pump. In conclusion, it is shown that, by far, the greatest impact on the bandwidth frequency may be achieved by reducing the swept volume of the control actuator and by increasing the flow capacity of the control valve.

scholarly journals Applying optimal control theory to complex epidemiological models to inform real-world disease management

2018 ◽  
Author(s):  
E.H. Bussell ◽  
C.E. Dangerfield ◽  
C.A. Gilligan ◽  
N.J. Cunniffe
Keyword(s):  
Optimal Control ◽  
Disease Management ◽  
Control Theory ◽  
Simulation Model ◽  
Optimal Control Theory ◽  
Management Strategies ◽  
Simulation Models ◽  
Open Loop ◽  
Small Subset ◽  
Control Disease

SummaryMathematical models provide a rational basis to inform how, where and when to control disease. Assuming an accurate spatially-explicit simulation model can be fitted to spread data, it is straightforward to use it to test the performance of a range of management strategies. However, the typical complexity of simulation models and the vast set of possible controls mean that only a small subset of all possible strategies can ever be tested. An alternative approach – optimal control theory – allows the very best control to be identified unambiguously. However, the complexity of the underpinning mathematics means that disease models used to identify this optimum must be very simple. We highlight two frameworks for bridging the gap between detailed epidemic simulations and optimal control theory: open-loop and model predictive control. Both these frameworks approximate a simulation model with a simpler model more amenable to mathematical analysis. Using an illustrative example model we show the benefits of using feedback control, in which the approximation and control are updated as the epidemic progresses. Our work illustrates a new methodology to allow the insights of optimal control theory to inform practical disease management strategies, with the potential for application to diseases of plants, animals and humans.

Numerical Study Optimal Timing of the Axial Piston Pump

2011 ◽  
Author(s):  
Shusen Zhang ◽  
Noah D. Manring ◽  
Viral S. Mehta
Keyword(s):  
Numerical Study ◽  
Dynamic Pressure ◽  
Piston Pump ◽  
Optimal Timing ◽  
Axial Piston Pump ◽  
Pump Design ◽  
Inlet Port ◽  
Actual Design ◽  
Pressure Ripple ◽  
Axial Piston

In this paper, the theoretical optimal timing of the axial piston pump is first derived to confirm the analysis published by Professor Kevin Edge [1]. It is discovered that the optimal discharge port delay is different from the optimal inlet port delay. The dimensional analysis also shows that higher shaft angular velocity indicates less delay required in both discharge port and inlet port. Numerical studies show that optimal timing can reduce the dynamic pressure ripple greatly, but since it does not affect the kinematic component, it will not eliminate the entire pressure ripple. The optimal timing could also induce an increase in efficiency where the baseline pump design has cross-porting. However, there is certain tradeoff between pressure ripple reduction and efficiency consideration. Actual design consideration to affect independent timing of the portplate is not studied in this work.

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