High dynamic digital control for a hydraulic cylinder drive

2021 ◽  
pp. 095965182110280
Author(s):  
Helmut Kogler
Keyword(s):  
Dynamic Response ◽  
Closed Loop ◽  
Position Control ◽  
Feedforward Control ◽  
Control Strategies ◽  
Frequency Control ◽  
Hydraulic Cylinder ◽  
Pulse Frequency ◽  
Pulse Code Modulation ◽  
High Dynamic

The control of hydraulic cylinders with digital hydraulic valves is often based on modulation principles like pulse-width modulation, pulse-code modulation, or pulse–frequency control. In many cases the dynamic drive performance using such control strategies is far below the natural dynamics of the system, since closed-loop controllers demand a certain phase margin for stability. However, some drive applications require a high dynamic response, which cannot be realized with common closed-loop concepts. In this article the design of a bang–bang feedforward control with regard to the dynamics of a hydraulic cylinder drive in accordance with the theory of optimal control is presented. The control achieves the maximum physical dynamic response and no remaining oscillations after the movement, which forms the basis of a high dynamic three-level position control for hydraulic drives. Furthermore, the influence of valve dynamics and pipe line dynamics with regard to the design of the digital valve control are considered by simulations.

scholarly journals Conventional and Fuzzy Force Control in Robotised Machining

2013 ◽  
Vol 210 ◽  
pp. 178-185 ◽  
Author(s):  
Zenon Hendzel ◽  
Andrzej Burghardt ◽  
Piotr Gierlak ◽  
Marcin Szuster
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Force Control ◽  
Closed Loop ◽  
Position Control ◽  
Control Strategies ◽  
Closed Loop System ◽  
Fuzzy Logic Systems ◽  
Complex Control System ◽  
Artificial Neural

This article presents an application of the hybrid position-force control of the robotic manipulator with use of artificial neural networks and fuzzy logic systems in complex control system. The mathematical description of the manipulator and a closed-loop system are presented. In the position control were used the PD controller and artificial neural networks, which compensate nonlinearities of the manipulator. The paper presents mainly the application of various strategies of the force control. The force control strategies using conventional controllers P, PI, PD, PID and fuzzy controllers are presented and discussed. All of the control methods were verified on the real object in order to make a comparison of a control quality.

Simulation and Analysis on Main Synchronized Hydraulic Cylinder of Huge Hydraulic Press

2012 ◽  
Vol 233 ◽  
pp. 150-153
Author(s):  
Jin Yu ◽  
Ming Zhen Fan ◽  
Guo Qin Huang ◽  
Min Yu
Keyword(s):  
Closed Loop ◽  
Position Control ◽  
Response Speed ◽  
Hydraulic Cylinder ◽  
Hydraulic Press ◽  
Loop Control ◽  
Piston Cylinder ◽  
The Press ◽  
Hydraulic Cylinders ◽  
Position Control System

Nowadays, huge hydraulic press plays an important role in the heavy industry. The synchronized hydraulic cylinder is the key component, which will affect the performance of the press. Thus, a thorough investigation to the main cylinder is required. In this paper, a mathematical model was built for the position closed-loop control of active synchronous hydraulic cylinders, and transfer function of the corresponding single cylinder was deduced. Simulation and calibration of the working cylinder servo position control system was accomplished with MATLAB, so as to improve the response speed and stability of the single working cylinder system. The results showed that a single hydraulic piston cylinder had a better position control features, which offered a theory basis for the design of the main drivers of forging hydraulic machine synchronization system.

Co-Simulation Based Design and Experimental Validation of Control Strategies for Digital Fluid Power Systems

2013 ◽  
Author(s):  
Maciej Z. Pindera ◽  
Yuzhi Sun ◽  
Jean-Jacques Malosse ◽  
Jose M. Garcia
Keyword(s):  
Power Systems ◽  
Data Exchange ◽  
Position Control ◽  
Control Strategies ◽  
Hydraulic Cylinder ◽  
Computational Time ◽  
Computationally Efficient ◽  
Precise Control ◽  
Fluid Power Systems ◽  
Opening And Closing

This work presents and experimentally validates the use of co-simulations in the virtual prototyping of control strategies for a digital hydraulic system. Co-simulations allow analysis of complex systems by partitioning the latter into a collection of well defined, interacting sub-systems and components. This approach is well suited for analysis of digital hydraulics. The system under consideration is composed of four two way, two position, on-off solenoid poppet valves connected to a double rod hydraulic cylinder actuator. The control task is to schedule the opening and closing of the valves to provide precise control of the requested actuator position. The actuator and valve dynamics are modeled as lumped parameter systems given by first order Ordinary Differential Equations (ODEs). The equations are solved simultaneously using a computationally efficient Chebyshev expansion approach. All co-simulations took no more than 10 seconds of computational time to execute on a standard PC with an Intel Core i7 processor. The valve and piston dynamics are fully coupled through exchange of flowrate and pressure data between the appropriate components. Coupling and data exchange were performed using the co-simulation environment CoSIM, which allows connection of arbitrary number of components in arbitrary configurations. The valve actuation strategies were based on selected versions of Bang-Bang control. The most successful was able to keep the actuator displacement with practically no oscillations about the requested set point. Preliminary results show that excellent position control characteristics can be obtained to within 2–3 percent of experimental data.

A Basic Study on the Response Dynamics of Pulse-Frequency Controlled Digital Hydraulic Drives

2013 ◽  
Author(s):  
Christoph Gradl ◽  
Rudolf Scheidl
Keyword(s):  
Pulse Width ◽  
Pulse Width Modulation ◽  
Control Strategies ◽  
Frequency Control ◽  
Hydraulic Drive ◽  
Pulse Frequency ◽  
Control Input ◽  
Response Dynamics ◽  
Basic Study ◽  
Performance Requirements

Various control strategies in digital hydraulics have been proposed and studied so far. In hydraulic switching control Pulse Width Modulation (PWM) of one or two switching valves was mostly considered. This paper deals with Pulse Frequency Control (PFC) which — opposite to PWM — uses the pulse repeating frequency and not the pulse width as control input. PFC may be to be preferred if the hydraulic switching device can realize a very particular pulse in a quite favorable way. This paper studies the influences of the flow rate pulse shapes and of the pulse frequency on the overall system dynamics. Based on a dimensionless mathematical model of a simple linear hydraulic drive and on elementary performance requirements (e.g. overshooting and pressure pulsations) dimensioning rules are derived. In addition to a repeated pulsing single or just a few pulses are investigated. It turns out that particular single or twin pulses can realize stepping motions of the drive without subsequent pulsations. In this way a hydraulic stepping drive can be realized. In case of repeated pulsing, high pulsing frequencies, in particular frequencies well above the natural frequency of the drive system, reduce oscillations considerably. Such frequencies may be realized either by one high frequency pulse device or by several pulse devices which are arranged in parallel and are operated in a phase shifted mode.

Finite-Time Settling Control of a Flexible Arm

1994 ◽  
Vol 208 (2) ◽  
pp. 79-87 ◽  
Author(s):  
S Choura
Keyword(s):  
Control Strategy ◽  
Finite Time ◽  
Position Control ◽  
Feedforward Control ◽  
Control Strategies ◽  
State Space Model ◽  
Control Law ◽  
Flexible Beam ◽  
Flexible Arm ◽  
Finite Set

This paper considers the position control of a flexible beam attached to a rotating rigid hub. The control torque is applied at the hub through a motor. A state-space model describing the motion of the flexible beam is developed and is employed in the design of the control law. The finite-time settling control strategy that combines feedback and feedforward is applied to the beam problem. The feedback part is separately designed to resolve the issues of asymptotic stability and robustness to uncertainties. The feedforward part simultaneously suppresses the rigid-body mode and a finite set of flexible modes at the end of manoeuvre and, therefore, it is the part responsible for the finite-time settling of the beam to its final configuration. It is shown that if the finite-time settling control is compared with previously developed control strategies under the same input bound constraint, it leads to a better suppression of vibrations at the end of manoeuvre, provided that a sufficient number of flexible modes are incorporated in the computation of the feedforward control law. A robustness test is carried out to show the viability of the control strategy supported by computer simulations.

Experimental investigation and propulsion control for a bio-inspired robotic undulatory fin

Robotica ◽  
2015 ◽  
Vol 33 (5) ◽  
pp. 1062-1084 ◽  
Author(s):  
Michael Sfakiotakis ◽  
John Fasoulas ◽  
Manolis M. Kavoussanos ◽  
Manolis Arapis
Keyword(s):  
Closed Loop ◽  
Position Control ◽  
Control Strategies ◽  
Underwater Vehicles ◽  
Open Loop ◽  
Water Tank ◽  
Velocity Control ◽  
Wave Kinematics ◽  
Propulsion Control ◽  
Simultaneous Adjustment

SUMMARYUndulatory fin propulsion, inspired by the locomotion of aquatic species such as electric eels and cuttlefish, holds considerable potential for endowing underwater vehicles with enhanced propulsion and maneuvering abilities, to address the needs of a growing number of applications. However, there are still gaps in our understanding of the effect of the fin undulations' characteristics on the generated thrust, particularly within the context of developing propulsion control strategies for such robotic systems. Towards this end, we present the design and experimental evaluation of a robotic fin prototype, comprised of eight individually-actuated fin rays. An artificial central pattern generator (CPG) is used to produce the rays' undulatory motion pattern. Experiments are performed inside a water tank, with the robotic fin suspended from a carriage, whose motion is constrained via a linear guide. The results from a series of detailed parametric investigations reveal several important findings regarding the effect of the undulatory wave kinematics on the propulsion speed and efficiency. Based on these findings, two alternative strategies for propulsion control of the robotic fin are proposed. In the first one, the speed is varied through changes in the undulation amplitude, while the second one involves simultaneous adjustment of the undulation frequency and number of waves. These two strategies are evaluated via experiments demonstrating open-loop velocity control, as well as closed-loop position control of the prototype.

scholarly journals Displacement Control of Flexible Structures Using Electrohydraulic Servo-Actuators

1985 ◽  
Vol 107 (1) ◽  
pp. 34-39 ◽  
Author(s):  
N. H. McClamroch
Keyword(s):  
Closed Loop ◽  
Force Feedback ◽  
Position Control ◽  
Feedforward Control ◽  
Flexible Structures ◽  
Direct Consequence ◽  
Linear Feedback ◽  
Acceleration Feedback ◽  
Control Forces ◽  
Actuator Control

A general approach to the displacement or position control of a nonlinear flexible structure using electrohydraulic servo actuators is developed. Our approach makes use of linear feedback of measured structural displacements plus linear feedback of the actuator control forces; a nonlinear feedforward function of the displacement command is also used for control. Based on a mathematical model of the closed loop, general conditions for closed loop stability are obtained. In the special case that the feedback is decentralized the stabilization conditions are stated in terms of simple inequalities; moreover, the stabilization conditions are robust to structural uncertainties since the conditions do not depend on explicit properties of the structure. Such robustness is a direct consequence of use of force feedback rather than, for example, acceleration feedback. Conditions are also developed for selection of the feedforward control to achieve zero steady state error; but this condition does depend on explicit properties of the structure. The theoretical results developed in the paper should provide a framework for advanced applications of control of mechanical systems using electrohydraulic servo-actuators.

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