Electropneumatic Actuator Research Articles

Nonlinear optimal control for robotic exoskeletons with electropneumatic actuators

Nonlinear optimal control for robotic exoskeletons with electropneumatic actuators

Predictive Model Control and Intelligent Agent are Used To Optimize The Precision Control of an Electro-Pneumatic Actuator-Based Robotic Bottle Capper

The inferior corking performance observed in bottled drinks from breweries is attributed to poor precision. To address this issue, an enhanced precision control system for an electro-pneumatic actuator-based bottle capper is introduced, utilizing model predictive control and intelligent agent technologies. This involves characterizing the electro-pneumatic actuator system, developing a conventional model for the robotic bottle capper, and designing a rule base to improve precision in the capping mechanism, thereby boosting production capacity per unit time. To achieve this, AI is trained to design a rule-based model ensuring optimal efficacy of the capping mechanism, thus enhancing the brewery industry's production capacity and revenue generation. A SIMULINK model is developed to demonstrate the improved precision control of the electro-pneumatic actuator robotic bottle capper using model predictive control and intelligent agent. Results show a significant increase in corking precision from 94.4% with conventional methods to 99.9% when intelligent agents are incorporated into the system. This translates to a 5.5% improvement in corking precision, with production capacity increasing from 27,000 crates using conventional methods to 28,570 with model predictive control. Moreover, with the integration of intelligence, the production capacity further rises to 342,500 bottles.

Simulation of transient response of PID controller in an automated electro-pneumatic system using a single-acting cylinder in a clinical ventilator

Patients with COVID-19 are not eligible for any therapy. Patients who have had respiratory failure and are unable to provide oxygen via noninvasive means obtain supportive care in ICUs. Since the onset of the outbreak, every sick COVID-19 patient has received oxygen via a mechanical ventilator. This study describes and simulates the transient stability of systems in an automated pressure regulator utilizing a single-acting cylinder in a clinical ventilator. These components include horizontal controllers, control devices, connecting tubes, and PID for electro-pneumatic control. Increased system stability and nonlinearity in electro-pneumatic actuator systems are accomplished by the implementation of PID. The redesigned PID control architecture was enhanced with alternative acceleration feedback through the close loop with an integral control method to get the system stable. This introduces the standard value N from the outside vicious circle and applies a form control law to integrate all reference control supply through into the gadget. Even as proportional gain (Kp) gets increased, the controller output would increase proportionately while maintaining the exact degree of accuracy. A derivative term boosts the ability of the Kd regulator to "detect" malfunctions. The integral term of the Ki controller minimizes its set point distortion. The system was updated to make it feasible for transferrable knowledge and competencies by incorporating real industrial components. The completed fluid control system was simulated through FluidSIM, which is frequently helpful for educational purposes.

Flatness-based control in successive loops for electropneumatic actuators and robots

The control problem for the nonlinear dynamics of robotic and mechatronic systems with electropneumatic actuation is solved with the use of a flatness-based control approach which is implemented in successive loops. The state-space model of these systems is separated into a series of subsystems, which are connected between them in cascading loops. Each one of these subsystems can be viewed independently as a differentially flat system and control about it can be performed with inversion of its dynamics as in the case of input–output linearized flat systems. In this chain of i=1,2,…,N subsystems, the state variables of the subsequent (i+1th) subsystem become virtual control inputs for the preceding (ith) subsystem, and so on. In turn, exogenous control inputs are applied to the last subsystem and are computed by tracing backwards the virtual control inputs of the preceding N−1 subsystems. The whole control method is implemented in successive loops and its global stability properties are also proven through Lyapunov stability analysis. The validity of the control method is confirmed in two case studies: (a) control of an electropneumatic actuator, (ii) control of a multi-DOF robotic manipulator with electropneumatic actuators.

Improved Pole-placement Control with Feed-forward Dead Zone Compensation for Position Tracking of Electro-Pneumatic Actuator System Improved Pole-placement Control with Feed-forward Dead Zone Compensation for Position Tracking of Electro-Pneumatic Actuato

Dead-zone in the valve degraded the performances of the Electro-Pneumatic Actuator (EPA) system. It makes the system difficult to control, become unstable and leads to chattering effect nearest desired position. In order to cater this issue, the EPA system transfer function and the dead-zone model is identified by MATLAB SI toolbox and the Particle Swarm Optimization (PSO) algorithm respectively. Then a parametric control is designed based on pole-placement approach and combine with feed-forward inverse dead-zone compensation. To reduce chattering effect, a smooth parameter is added to the controller output. The advantages of using these techniques are the chattering effect and the dead-zone of the EPA system is reduced. Moreover, the feed-forward system improves the transient performance. The results are compared with the pole-placement control (1) without compensator and (2) with conventional dead-zone compensator. Based on the experimental results, the proposed controller reduced the chattering effect due to the controller output of conventional dead-zone compensation, 90% of the pole-placement controller steady-state error and 30% and 40% of the pole-placement controller with conventional dead-zone compensation settling time and rise time.

Integrated Prognostics Observer for Condition Monitoring of an Automated Manual Transmission Dry Clutch System

The closed loop feedback control system of an Automated Manual Transmission (AMT) electro-pneumatic clutch actuator is used for intelligent real time condition monitoring, enhanced diagnostics and prognostic health management of the dry clutch system, by integrating with the existing gearbox prognostics observer. The real-time sensor data of the clutch actuator piston position is analyzed for monitoring the condition of the clutch system. Original parameters of the new clutch are stored in the Electrically Erasable Programmable Read-only Memory (EEPROM) of the AMT controller and the real-time data is used by the observer for assessing the degradation/wear of the frictional clutch parts. Also, clutch slip during torque transmission is monitored, using the engine speed and the gearbox input shaft speed from Controller Area Network (CAN). Condition monitoring of clutch system provides enhanced prognostic functionality for AMT system which ensures consistent clutch performance, gear shift quality and timely warning for recalibration, repair and/or replacement of the critical wear and tear parts. Also, systematic analysis of the monitored data provides an accurate diagnosis of a developing fault. Thus, with the advanced control systems in place for AMT, a closed loop feedback based condition monitoring system is modelled for improved diagnostics and prognostics of AMT clutch system.

Direct adaptive fuzzy position controller for an electropneumatic actuator: Design and experimental evaluation

This paper proposes a direct adaptive fuzzy position controller for an electropneumatic actuator. This control approach is based on the estimation of an ideal inverse dynamic control, which is capable of satisfying the control objectives in terms of tracking desired trajectories and stability. For this purpose, a fuzzy system is used to approximate as best as possible this ideal inverse dynamic control. The adjustable parameters of the used fuzzy system are updated online with a stable adaptation law. This latter is developed in order to minimize the error between the unknown ideal inverse dynamic control and the used fuzzy controller. The general non-affine model of the controlled actuator is used to develop the control law and its adaptation mechanism, meaning that the presented adaptive fuzzy position controller does not rely on a physical model of the pneumatic actuator. The stability of the closed-loop system is performed using a Lyapunov approach. Finally, real-time experimental results are presented to show the performances of the proposed position controller.

Control Design and Validation for Floating Piston Electro-Pneumatic Gearbox Actuator

The paper presents the modeling and control design of a floating piston electro-pneumatic gearbox actuator and, moreover, the industrial validation of the controller system. As part of a heavy-duty vehicle, it needs to meet strict and contradictory requirements and units applying the system with different supply pressures in order to operate under various environmental conditions. Because of the high control frequency domain of the real system, post-modern control methods with high computational demands could not be used as they do not meet real-time requirements on automotive level. During the modeling phase, the essential simplifications are shown with the awareness of the trade-off between calculation speed and numerical accuracy to generate a multi-state piecewise-linear system. Two LTI control methods are introduced, i.e., a PD and an Linear-Quadratic Regulators (LQR) solution, in which the continuous control signals are transformed into discrete voltage solenoid commands for the valves. The validation of both the model and the control system are performed on a real physical implementation. The results show that both modeling and control design are suitable for the control tasks using floating piston cylinders and, moreover, these methods can be extended to electro-pneumatic cylinders with different layouts.

High-Order Sliding-Mode Control With Predefined Convergence Time for Electropneumatic Actuator

In this brief, a control technique is proposed to achieve finite-time trajectory tracking of the position of a perturbed electropneumatic actuator. This controller guarantees the convergence at exactly a predefined convergence time $t_{F}$ . It is based on the integral sliding-mode concept, and is composed of two terms: a first one named nominal control which is designed to obtain desired performances (convergence time) for the disturbance free system, and a second robust control , based on super-twisting algorithm for the disturbance compensation. This brief presents its practical implementation to an electropneumatic actuator, in single-output (SISO) and multi-input multi-output (MIMO) contexts. The robustness of the control law is discussed with respect to external disturbances.

A New Varying-Gain-Exponent-Based Differentiator/Observer: An Efficient Balance Between Linear and Sliding-Mode Algorithms

It is well known that the supertwisting algorithm is robust to matched perturbation but is sensitive to measurement noise. Contrary to this, the classical linear algorithm is less sensitive to measurement noise but less robust to perturbation. To combine both the good accuracy of the supertwisting algorithm with respect to perturbation and the good performance of the linear algorithm with respect to measurement noise, this article proposes a new differentiator/observer with a varying exponent gain α whose variation depends on the magnitude of measurement noise (high-frequency signal). When the magnitude of measurement noise increases (respectively, decreases) α tends to 1 (respectively, tends to 0.5) and the proposed differentiator/observer behaves as a linear algorithm (respectively, as a supertwisting algorithm). Thus, by one parameter α, the differentiator/observer can take care of high-frequency noise and matched perturbations. A complete stability analysis of the proposed differentiator/observer is provided. To highlight the applicability of the proposed methodology, the dedicated differentiator/observer is, respectively, validated on the electropneumatic actuator and electric machine test benches. These experimental results are compared to those of linear and supertwisting algorithms.

New Robust Control Schemes Based on Both Linear and Sliding Mode Approaches: Design and Application to an Electropneumatic Actuator

New control schemes based on sliding mode control and linear state feedback are proposed to ensure high tracking accuracy with relatively low energy consumption. A time-varying exponent parameter law (linked to homogeneity degree) is introduced to combine the advantages of sliding mode control (high accuracy and robustness) and the linear state feedback (low energy consumption). To show the effectiveness of the proposed approaches, experimental tests are conducted on an electropneumatic setup.

Linear-Quadratic Tracking Control of a Commercial Vehicle Air Brake System

This article proposes to utilize linear-quadratic tracking (LQT) control to reduce the air brake system response time and vehicle stopping distance, and hence, to significantly improve the system performance of a commercial vehicle air brake system equipped with electro-pneumatic proportional valve actuators. The nonlinear dynamic model of the air brake system, consisting of a control actuator (a proportional valve) and braking actuator (the brake chamber), is developed and linearized using the q-Markov COVariance Equivalent Realization (q-Markov Cover) method in our early work. Based on the linearized dynamic model, an infinite horizon LQT controller is designed along with Kalman state estimation at each linearized operational condition. To apply the LQT control law over a wide operational range to track the target pressure, the designed controller was interpolated between the neighboring controllers to have a control law cover the entire operational range. To validate this control law, the control scheme is implemented into a dSPACE unit and validated through bench tests under different supply and reference pressures. The LQT control performance is also compared with the PID (proportional-integral-derivative) one. The bench test results confirm the effectiveness of the proposed control scheme.

Reinforcement Learning Based Control Design for a Floating Piston Pneumatic Gearbox Actuator

Electro-pneumatic actuators play an essential role in various areas of the industry, including heavy-duty vehicles. This article deals with the control problem of an Automatic Manual Transmission, where the actuator of the system is a double-acting floating-piston cylinder, with dedicated inner-position. During the control design of electro-pneumatic cylinders, one must implement a set-valued control on a nonlinear system, when, as in the present case, non-proportional valves provide the airflow. As both the system model itself and the qualitative control goals can be formulated as a Partially Observable Markov Decision Process, Machine learning frameworks are a conspicuous choice for handling such control problems. To this end, six different solutions are compared in the article, of which a new agent named PG-MCTS, using a modified version of the “Upper Confidence bound for Trees” algorithm, is also presented. The performance and strategic choice comparison of the six methods are carried out in a simulation environment. Validation tests performed on an actual transmission system and implemented on an automotive control unit to prove the applicability of the concept. In this case, a Policy Gradient agent, selected by implementation and computation capacity restrictions. The results show that the presented methods are suitable for the control of floating-piston cylinders and can be extended to other fluid mechanical actuators, or even different set-valued nonlinear control problems.

Measurement Based Validation of an Electro-Pneumatic Gearbox Actuator

The objective of the research is to analyze the behavior of the developed electro-pneumatic actuator model and compare it to the behavior of the real system. The actuator achieves the requested gear changes by moving the two pistons inside the cylinder and it is operated by three-way two-position solenoid valves. Since not all model parameters are exactly known, such as contraction coefficients and friction parameters, they can be estimated based on literature then they can be further tuned to minimize the error of the simulation. The developed nonlinear model is capable of describing the dynamic behavior of the gearbox actuator, thus it can be used to analyze the effects of constructional modifications and it can serve as Model in the Loop (MIL) environment for controller testing.

EXPERIMENTAL STUDY OF TACTICAL AND TECHNICAL CHARACTERISTICS OF THE ELECTRIC DRIVE OF A STRIKEBALL WEAPON.

Electro-pneumatic actuator is an accurate external modulation of combat weapons, which is used for tactical games and development of combat skills. Electro-pneumatic drive (AEG) and its advantage in high speed of fire were investigated in the experiment and the number of its shots exceeds even the number of combat weapon's shots. The other advantages are the large number of shots on a standard battery and miniature design, because weight and size are more modulation requirement than necessity.

FEATURES OF CONTROLLING ELECTROPNEUMATIC VALVES OF ACTUATOR TO CONTROL ITS CLUTCH WITH ACCELERATION VALVE

The article deals with one of the ways to control an actuator of the automated clutch control system. The aim is to design control of the electropneumatic actuator, to control its coupling with the acceleration valve on the basis of experimental research as well as to provide rational parameters of the automated clutch control system for the robotic transmission. The feature of the system is an acceleration valve in the design of the electropneumatic actuator to control the clutch. New links demand to adjust the way to control the actuator. The connection of Pulse-Width Modulation (PWM) with single power supply pulses to control electropneumatic valves is substantiated. The quantitative characteristics of single control pulses and PWM ones are determined. The error of operation accuracy for various ways of the control of the electropneumatic actuator to control the clutch of the robotic transmission is determined. Obtained separate PWM area is designed to suppress the initial hysteresis when the rod of the clutch actuator is moved. An algorithm for the operation of a clutch control system is proposed, taking into account the use of two modes of operation of solenoid valves. A graphical interpretation of the clutch control algorithm is presented, which gives an idea of the location of the constant signal feeding zones to the solenoid valve, as well as the operation areas of the solenoid valve in PWM mode. The control algorithm of the clutch booster provides a mode of guaranteed absence of excess pressure in the pneumatic cylinder after releasing the clutch pedal, provided that two normally closed solenoid valves are used. This configuration of the electro-pneumatic clutch control system allows the use of an emergency clutch release system in case of voltage absence. The reference algorithm for filtering the array of data coming from the feedback sensor, as well as the numerical values of the delay caused by the presence of a filter, are given.

Modeling and PWM Control of Electro-Pneumatic Actuator for Missile Applications.

The Electro-Pneumatic Actuators (EPAs) using ON/OFF type solenoid valves are very popular in aerospace applications due to their robustness, simplicity, high Torque/Weight ratio, fast speed of response, etc. This paper deals with the modeling, simulation, plant characterization, design of a Pulse Width Modulation (PWM) Controller and model validation of an EPA used in missile applications. The EPA used in this work consists of 3-way, 2-position, ON-OFF type solenoid valves. A non-linear mathematical model of the EPA has been developed and implemented in the MATLAB/SIMULINK environment to carry out the simulation studies. The plant model is characterized in the experiment using Frequency Response Analysis (FRA). A Single Sided Pulse Width Modulation (SSPWM) Controller with phase lead-lag compensators and a proportional gain has been designed for the closed loop position control of the missile fin servo. The model is validated by comparing the experimental closed loop time responses with the simulation.

Experimental analysis of electro-pneumatic optimization of hot stamping machine control systems with on-delay timer

The sustainability criterion in the manufacturing industries is imperative, especially in the automobile industries. Currently, efforts are being made by the industries to mitigate CO2 emission by the total vehicle weight optimization, machine utilization and resource efficiency. In lieu of this, it is important to understudy the manufacturing machines adopted in the automobile industries. One of such machine is the hot stamping machine that is used for about 35% of the manufacturing operations within the automobile industries. Therefore, the standardization and optimization of the hot stamping process could reduce the carbon footprint within the automobile industries. This work understudied the on-delay timer functional valve of the hot stamping machine in order to determine various process parameters affecting it. The detailed physical model of the pneumatic and electro-pneumatic cylinder systems for the control is simulated and optimized for both the pneumatic and electro-pneumatic cylinder systems. Experimental and simulation model were established at the FESTO work station and FESTO FluidSIM® 5.1 respectively to evaluate the effective velocity, accelerations, displacement, and flow rate for the pneumatic and electro-pneumatic actuator on both systems. Comparisons were made between pneumatic and electro-pneumatic cylinder systems on their characteristic curve in order to optimize the process variables. The result favours the electro-pneumatic cylinder systems in stability and in designing hot stamping machines. The result obtained could elucidate the understanding of the pressing arm of a hot stamping machine.

Adaptive Pulse Output Feedback Controller Based on Second-Order Sliding Mode: Methodology and Application

This brief 1 proposes an adaptive version of a second-order sliding mode (SOSM) controller with a gain for which switching variations are forced under some adequate conditions. The sampled controller requires no time derivative of the sliding variable but only the sign of the sliding variable. A practical SOSM is ensured in spite of bounded perturbations and uncertainties with unknown bounds. The gain adaptation law ensures obtaining a sufficient gain required for the convergence of the system. The methodological and experimental results are presented in this brief, the experimental part concerning the application of the proposed adaptive controller to the position control of an electropneumatic actuator. 1 A preliminary version of this brief has been presented at European Control Conference ECC’13 , Zurich, Switzerland, 2013.

Electropneumatic actuator position control using second order sliding mode

Pneumatic actuators are quite difficult to control in an accurate way. Indeed their dynamics are generally described by an uncertain nonlinear system. The uncertainties are caused by friction, (external) perturbations and parametric uncertainties due to a very tedious identification process. This paper deals with the position control problem of an electropneumatic actuator using sliding mode control.