scholarly journals Modelling And Control Of Automated Polishing/Deburring Process

2021 ◽  
Author(s):  
Liang Liao
Keyword(s):  
Feedback Linearization ◽  
Closed Loop ◽  
Control Method ◽  
Minimum Degree ◽  
Open Loop ◽  
Pole Placement ◽  
Control Performance ◽  
Nonlinear Controller ◽  
Loop Control ◽  
And Control

In this thesis, a new approach is presented for the modelling and control of an automated polishing/deburring process that utilizes a dual-purpose complaint toolhead mounted on a parallel tripod robot. This toolhead has a pneumatic spindle that can be extended and retracted by three pneumatic actuators to provide tool compliance. By integrating a pressure sensor and a linear encoder, this toolhead can be used for polishing and deburring. For the polishing open-loop control, the desired tool pressure is pre-planned based on the given part geometry. To improve control performance, a closed-loop controller is applied for pressure tracking through pressure sensing. For the deburring control, another closed-loop controller is applied to regulate the tool length through tool extension sensing. The two control methods have been tested and implemented on a polishing/deburring robot, and the experiment results demonstrate the effectiveness of the presented methods. To future improve the control performance, an adaptive controller is developed to deal with the uncertainties in the compliant tool. This control method combines the adaptive control theory with the constant stress theory of the contact model. A recursive last squares (RLS) estimator is developed to estimate the pneumatic plant model, and then a minimum-degree pole placement (MDPP) is applied to design a self-tuning controller. Afterwards, the simulation and experiment results of the proposed controller are presented and discussed. Finally, a nonlinear model of the pneumatic plant is developed. The nonlinear controller developed by using feedback linearization method is applied on the nonlinear pneumatic system of the compliant toolhead. The simulation is carried out to test the effectiveness of the pressure tracking for the polishing process.

scholarly journals Modelling And Control Of Automated Polishing/Deburring Process

2021 ◽  
Author(s):  
Liang Liao
Keyword(s):  
Feedback Linearization ◽  
Closed Loop ◽  
Control Method ◽  
Minimum Degree ◽  
Open Loop ◽  
Pole Placement ◽  
Control Performance ◽  
Nonlinear Controller ◽  
Loop Control ◽  
And Control

In this thesis, a new approach is presented for the modelling and control of an automated polishing/deburring process that utilizes a dual-purpose complaint toolhead mounted on a parallel tripod robot. This toolhead has a pneumatic spindle that can be extended and retracted by three pneumatic actuators to provide tool compliance. By integrating a pressure sensor and a linear encoder, this toolhead can be used for polishing and deburring. For the polishing open-loop control, the desired tool pressure is pre-planned based on the given part geometry. To improve control performance, a closed-loop controller is applied for pressure tracking through pressure sensing. For the deburring control, another closed-loop controller is applied to regulate the tool length through tool extension sensing. The two control methods have been tested and implemented on a polishing/deburring robot, and the experiment results demonstrate the effectiveness of the presented methods. To future improve the control performance, an adaptive controller is developed to deal with the uncertainties in the compliant tool. This control method combines the adaptive control theory with the constant stress theory of the contact model. A recursive last squares (RLS) estimator is developed to estimate the pneumatic plant model, and then a minimum-degree pole placement (MDPP) is applied to design a self-tuning controller. Afterwards, the simulation and experiment results of the proposed controller are presented and discussed. Finally, a nonlinear model of the pneumatic plant is developed. The nonlinear controller developed by using feedback linearization method is applied on the nonlinear pneumatic system of the compliant toolhead. The simulation is carried out to test the effectiveness of the pressure tracking for the polishing process.

The Effect of Local Force Control on Punch Forces During Panel Forming

2018 ◽  
Author(s):  
William J. Emblom
Keyword(s):  
Closed Loop ◽  
Force Transducer ◽  
Open Loop ◽  
Control Panel ◽  
Closed Loop Control ◽  
Punch Force ◽  
Blank Holder ◽  
Loop Control ◽  
Operational Envelope ◽  
And Control

Methods for improving the robustness of panel forming including the introduction of process sensing and feedback and control has resulted in significant gains in the quality of parts and reduced failures. Initial efforts in implementing closed-loop control during panel forming used active tool elements to ensure that the total punch force followed prescribed trajectories. However, more recently local forces within the tooling have been demonstrated to not only follow desired force trajectories but have been shown to increase the operational envelope of the tooling compared to open-loop tests and even closed-loop test where the total punch force had been controlled. However, what has not been examined is the effect of local force, especially during closed-loop control panel forming operations on the total punch force measured during forming. This paper addresses this by comparing the results of both open-loop tests and closed-loop tests and examining the effects on both local and total punch forces. It was found that while open-loop forming with various constant draw bead depths resulted in varying total punch forces, once closed-loop control was implemented the total punch forces followed virtually identical trajectories. The tooling for this project included local force transducers and a total punch force transducer. In addition, active draw beads could be controlled during forming and a flexible blank holder with variable blank holder forces were part of the setup.

Strain Control in an Intelligent Die Based Upon Local Force Control and Blank Holder Forces

2009 ◽  
Author(s):  
William J. Emblom ◽  
Klaus J. Weinmann ◽  
John E. Beard
Keyword(s):  
Closed Loop ◽  
Open Loop ◽  
Die Design ◽  
Closed Loop Control ◽  
Blank Holder Force ◽  
Punch Force ◽  
Blank Holder ◽  
Loop Control ◽  
And Control ◽  
Bead Penetration

An experimental evaluation of the strains in an oval stamp forming die is presented. The die design included a flexible blank holder and active draw beads. The die was instrumented with local punch force and wrinkle sensors and control systems were developed in order to follow local punch force and wrinkle trajectories. Strains were measured after pan forming for both open and closed-loop tests. The relation between blank holder force, draw bead penetration, and strains were explored in the critical strain region of the formed pan. Closed-loop control of the local punch forces at the die ends was established using blank holder forces. The strains for tests with various lubrication conditions and draw bead penetrations were compared. It was observed that there is a tendency for the strains in critical locations to converge or remain constant for the closed-loop control tests while the strains tended to increase with blank holder force for open-loop tests. It was concluded that by controlling local punch forces, strain is indirectly controlled.

Dynamics and Control of Global Instabilities in Open-Flows: A Linearized Approach

2010 ◽  
Vol 63 (3) ◽  
Author(s):  
Denis Sipp ◽  
Olivier Marquet ◽  
Philippe Meliga ◽  
Alexandre Barbagallo
Keyword(s):  
Closed Loop ◽  
Selection Process ◽  
Open Loop ◽  
Base Flow ◽  
Closed Loop Control ◽  
Mean Flow ◽  
Loop Control ◽  
Dynamics And Control ◽  
Global Modes ◽  
And Control

This review article addresses the dynamics and control of low-frequency unsteadiness, as observed in some aerodynamic applications. It presents a coherent and rigorous linearized approach, which enables both to describe the dynamics of commonly encountered open-flows and to design open-loop and closed-loop control strategies, in view of suppressing or delaying instabilities. The approach is global in the sense that both cross-stream and streamwise directions are discretized in the evolution operator. New light will therefore be shed on the streamwise properties of open-flows. In the case of oscillator flows, the unsteadiness is due to the existence of unstable global modes, i.e., unstable eigenfunctions of the linearized Navier–Stokes operator. The influence of nonlinearities on the dynamics is studied by deriving nonlinear amplitude equations, which accurately describe the dynamics of the flow in the vicinity of the bifurcation threshold. These equations also enable us to analyze the mean flow induced by the nonlinearities as well as the stability properties of this flow. The open-loop control of unsteadiness is then studied by a sensitivity analysis of the eigenvalues with respect to base-flow modifications. With this approach, we manage to a priori identify regions of the flow where a small control cylinder suppresses unsteadiness. Then, a closed-loop control approach was implemented for the case of an unstable open-cavity flow. We have combined model reduction techniques and optimal control theory to stabilize the unstable eigenvalues. Various reduced-order-models based on global modes, proper orthogonal decomposition modes, and balanced modes were tested and evaluated according to their ability to reproduce the input-output behavior between the actuator and the sensor. Finally, we consider the case of noise-amplifiers, such as boundary-layer flows and jets, which are stable when viewed in a global framework. The importance of the singular value decomposition of the global resolvent will be highlighted in order to understand the frequency selection process in such flows.

ADAPTIVE OPEN-PLUS-CLOSED-LOOP CONTROL METHOD OF MODIFIED FUNCTION PROJECTIVE SYNCHRONIZATION IN COMPLEX NETWORKS

2011 ◽  
Vol 22 (12) ◽  
pp. 1393-1407 ◽  
Author(s):  
HONGYUE DU
Keyword(s):  
Closed Loop ◽  
Control Method ◽  
Open Loop ◽  
Projective Synchronization ◽  
Closed Loop Control ◽  
Loop Control ◽  
Function Projective Synchronization ◽  
Advantages And Disadvantages ◽  
Modified Function Projective Synchronization ◽  
Loop Feedback

This paper investigates the modified function projective synchronization (MFPS) in drive-response dynamical networks (DRDNs) with different nodes, which means that systems in nodes are strictly different. An adaptive open-plus-closed-loop (AOPCL) control method is proposed, which is a practically realizable method and can overcome the model mismatched to achieve synchronization. It is well known that each of the close-loop and open-loop control method possesses some advantages and disadvantages. By combining their advantages, the open-plus-closed-loop (OPCL) control method was proposed by Jackson and Grosu. For arbitrary nonlinear dynamic systems, dx/dt = F(x,t), Jackson and Grosu proved that there exists solutions, x(t), in the neighborhood of any arbitrary goal dynamics g(t) that are entrained to g(t), through the use of an additive controlling action, K(g,x,t) = H(dg/dt,g) + C(g,t)(g(t) - x), which is the sum of the open-loop action, H(dg/dt,g), and a suitable linear closed-loop (feedback) action C(g,t). This method is a practically realizable method and robust to limited accuracy of data and effects of noise. The AOPCL control method preserve the merits of OPCL control method and its closed loop control part can be automatically adapted to suitable constants. Considering time-delays are always unavoidably in the practical situations, MFPS in DRDNs with time-varying coupling delayed is further investigated by the proposed method. Corresponding numerical simulations are performed to verify and illustrate the analytical results.

A New Close-Loop Control Method for an Inspection Robot Equipped with Electropermanent-Magnets

2016 ◽  
Vol 28 (2) ◽  
pp. 185-193 ◽  
Author(s):  
Pakpoom Kriengkomol ◽  
◽  
Kazuto Kamiyama ◽  
Masaru Kojima ◽  
Mitsuhiro Horade ◽  
...  
Keyword(s):  
Closed Loop ◽  
Control Method ◽  
Steel Structures ◽  
Open Loop ◽  
Closed Loop Control ◽  
Loop Control ◽  
Inspection Robot ◽  
Industrial Age ◽  
Set Up ◽  
Close Loop Control

[abstFig src='/00280002/09.jpg' width=""300"" text='ASTERISK use our proposed method to walk' ]Since the industrial age began, increasing numbers of manufacturing plants have been set up to serve economic growth demand. More bridges were built simultaneously to connect cities and to make transportation more convenient. As these facilities have aged, regular maintenance has increased. The limb mechanism project we started almost 20 years ago was to deliver new types of inspection and maintenance to industrial fields. Our first prototype, a six-limb robot called Asterisk, included such capabilities as walking on ceilings, climbing and descending stairs and ladders, walking tightropes, and transversing rough terrain. Asterisk's latest version uses electromagnets to work in antigravity environments such as steel structures. Unfortunately, this presented a major danger, requiring that we replace electromagnets with electropermanent magnets (EPMs). Limitations on EPMs, however, required a new control strategy. We propose and compare three control methods -- open-loop control, closed-loop control using torque feedback, and closed-loop control using angle feedback -- in the sections that follow. Our objective is to determine the best control for inspection robots having electropermanent magnets but not using additional sensors.

scholarly journals A Dynamic Model for the Evaluation of Aircraft Engine Icing Detection and Control-Based Mitigation Strategies

2017 ◽  
Author(s):  
Donald L. Simon ◽  
Aidan W. Rinehart ◽  
Scott M. Jones
Keyword(s):  
Closed Loop ◽  
Open Loop ◽  
Operating Conditions ◽  
Mitigation Strategies ◽  
System Level ◽  
Test Facility ◽  
Closed Loop Control ◽  
Turbofan Engine ◽  
Loop Control ◽  
And Control

Aircraft flying in regions of high ice crystal concentrations are susceptible to the buildup of ice within the compression system of their gas turbine engines. This ice buildup can restrict engine airflow and cause an uncommanded loss of thrust, also known as engine rollback, which poses a potential safety hazard. The aviation community is conducting research to understand this phenomena, and to identify avoidance and mitigation strategies to address the concern. To support this research, a dynamic turbofan engine model has been created to enable the development and evaluation of engine icing detection and control-based mitigation strategies. This model captures the dynamic engine response due to high ice water ingestion and the buildup of ice blockage in the engine’s low pressure compressor. It includes a fuel control system allowing engine closed-loop control effects during engine icing events to be emulated. The model also includes bleed air valve and horsepower extraction actuators that, when modulated, change overall engine operating performance. This system-level model has been developed and compared against test data acquired from an aircraft turbofan engine undergoing engine icing studies in an altitude test facility and also against outputs from the manufacturer’s customer deck. This paper will describe the model and show results of its dynamic response under open-loop and closed-loop control operating scenarios in the presence of ice blockage buildup compared against engine test cell data. Planned follow-on use of the model for the development and evaluation of icing detection and control-based mitigation strategies will also be discussed. The intent is to combine the model and control mitigation logic with an engine icing risk calculation tool capable of predicting the risk of engine icing based on current operating conditions. Upon detection of an operating region of risk for engine icing events, the control mitigation logic will seek to change the engine’s operating point to a region of lower risk through the modulation of available control actuators while maintaining the desired engine thrust output. Follow-on work will assess the feasibility and effectiveness of such control-based mitigation strategies.

scholarly journals Analysis of Dynamic Characteristics of a 600 kW Storage Type Wind Turbine with Hybrid Hydraulic Transmission

Processes ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 397 ◽  
Author(s):  
Zengguang Liu ◽  
Yanhua Tao ◽  
Liejiang Wei ◽  
Peng Zhan ◽  
Daling Yue
Keyword(s):  
Power Generation ◽  
Energy Storage ◽  
Wind Energy ◽  
Wind Turbine ◽  
Closed Loop ◽  
Control Method ◽  
Open Loop ◽  
Wheel Speed ◽  
Loop Control ◽  
Storage Type

In order to improve the efficiency and convenience of wind energy storage and solve the reproducibility of the hydraulic wind turbine, we present a storage type wind turbine with an innovative hybrid hydraulic transmission, which was adopted in the development of a 600 kW storage type wind turbine experimental platform. The whole hydraulic system of the storage type wind turbine is mainly an ingenious combination of a closed loop transmission and an open loop one, which can also be divided into three parts: hydraulic variable speed, hydraulic energy storage, power generation. For the study focusing on the capture and storage of wind energy, the mathematical model of the wind turbine except for the power generation was established under MATLAB/Simulink. A double closed loop control strategy is proposed to achieve the wind wheel speed regulation and wind energy storage. The dynamic simulations of the 600 kW storage type wind turbine experimental prototype were carried out under two different input signals. The results show that the wind wheel speed achieves the desired value at fast response and high precision using the control method given in this paper, and the proposed new storage type wind turbine is reasonable and practical.

scholarly journals High-bandwidth nanopositioning via active control of system resonance

2021 ◽  
Author(s):  
Linlin Li ◽  
Sumeet S. Aphale ◽  
Limin Zhu
Keyword(s):  
Resonant Frequency ◽  
Closed Loop ◽  
Performance Enhancement ◽  
Open Loop ◽  
Pole Placement ◽  
Loop Control ◽  
Damping Control ◽  
Significant Performance ◽  
High Bandwidth ◽  
Almost All

AbstractTypically, the achievable positioning bandwidth for piezo-actuated nanopositioners is severely limited by the first, lightly-damped resonance. To overcome this issue, a variety of open- and closed-loop control techniques that commonly combine damping and tracking actions, have been reported in literature. However, in almost all these cases, the achievable closed-loop bandwidth is still limited by the original open-loop resonant frequency of the respective positioning axis. Shifting this resonance to a higher frequency would undoubtedly result in a wider bandwidth. However, such a shift typically entails a major mechanical redesign of the nanopositioner. The integral resonant control (IRC) has been reported earlier to demonstrate the significant performance enhancement, robustness to parameter uncertainty, guaranteed stability and design flexibility it affords. To further exploit the IRC scheme’s capabilities, this paper presents a method of actively shifting the resonant frequency of a nanopositioner’s axis, thereby delivering a wider closed-loop positioning bandwidth when controlled with the IRC scheme. The IRC damping control is augmented with a standard integral tracking controller to improve positioning accuracy. And both damping and tracking control parameters are analytically optimized to result in a Butterworth Filter mimicking pole-placement—maximally flat passband response. Experiments are conducted on a nanopositioner’s axis with an open-loop resonance at 508 Hz. It is shown that by employing the active resonance shifting, the closed-loop positioning bandwidth is increased from 73 to 576 Hz. Consequently, the root-mean-square tracking errors for a 100 Hz triangular trajectory are reduced by 93%.

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