Desired Compensation Adaptive Robust Contouring Control of an Industrial Biaxial Precision Gantry Subject to Cogging Forces

2009 ◽  
Author(s):  
Chuxiong Hu ◽  
Bin Yao ◽  
Qingfeng Wang
Keyword(s):  
High Speed ◽  
Parametric Uncertainties ◽  
Control Performance ◽  
Linear Motors ◽  
Output Tracking ◽  
Control Scheme ◽  
Contouring Control ◽  
Contouring Accuracy ◽  
Sinusoidal Functions ◽  
Force Ripple

To obtain a higher level of contouring motion control performance for linear-motor-driven multi-axes mechanical systems subject to significant nonlinear cogging forces, both coordinated control of multi-axes motions and effective compensation of cogging forces are necessary. In addition, the effect of unavoidable velocity measurement noises needs to be carefully examined and sufficiently attenuated. To solve these problems simultaneously, in this paper, a discontinuous projection based desired compensation adaptive robust contouring controller is developed by explicitly taking into account the specific characteristics of cogging forces in the controller designs and employing the task coordinate formulation for coordinated motion controls. Specifically, based on the largely periodic nature of cogging forces with respect to position, design models consisting of known sinusoidal functions of positions corresponding to the main harmonics of the force ripple waveforms with unknown weights are used to approximate the unknown cogging forces. Theoretically, the resulting controller achieves a guaranteed transient performance and final contouring accuracy in the presence of both parametric uncertainties and uncertain nonlinearities. In addition, the controller also achieves asymptotic output tracking when there are parametric uncertainties only. Comparative experimental results obtained on a high-speed industrial biaxial precision gantry driven by linear motors are presented to verify the excellent contouring performance of the proposed control scheme and the effectiveness of the cogging force compensations.

Modeling and Synchronous Control of Dual Mechanically Coupled Linear Servo System

2014 ◽  
Vol 137 (4) ◽  
Author(s):  
Wu-Sung Yao
Keyword(s):  
Machine Tool ◽  
High Speed ◽  
Dynamic Stiffness ◽  
System Modeling ◽  
Coupled System ◽  
Mechanical Coupling ◽  
Synchronous Control ◽  
Linear Motors ◽  
Operation Speed ◽  
Control Scheme

This paper presents a system modeling technique for a high-speed gantry-type machine tool driven by linear motors. One feed axis of the investigated machine tool is driven by the joint thrust from two parallel linear motors. These two parallel motors are coupled mechanically to form the Y-axis while another standalone motor fixed to a support forms the X-axis. The components in the X-axis, which is treated as the mechanical coupling, are carried by the slides of the Y-axis motors. This configuration is applied to improve the dynamic stiffness of the system and operation speed/acceleration. However, the precise synchronous control of the two parallel and coupled motors would be the major challenge. To overcome this challenge, a multivariable system identification method is developed in this paper. This method is used to construct an accurate system mathematical model for the target coupled system. A synchronous control scheme is then applied to the model obtained using the proposed technique. The performance of the system is experimentally verified with a high-speed S-curve motion profile. The results substantiate the constructed system model and demonstrate the effectiveness of the control scheme.

Steady Vortex-Generator Jet Flow Control on a Highly Loaded Transonic Low-Pressure Turbine Cascade: Effects of Compressibility and Roughness

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
Chiara Bernardini ◽  
Stuart I. Benton ◽  
John D. Lee ◽  
Jeffrey P. Bons ◽  
Jen-Ping Chen ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Mach Number ◽  
Flow Control ◽  
High Speed ◽  
Vortex Generator ◽  
Control Performance ◽  
Low Pressure Turbine ◽  
Blowing Ratio ◽  
Turbulent Separation ◽  
Mach Number Distribution

A new high-speed linear cascade has been developed for low-pressure turbine (LPT) studies at The Ohio State University. A compressible LPT profile is tested in the facility and its baseline performance at different operating conditions is assessed by means of isentropic Mach number distribution and wake total pressure losses. Active flow control is implemented through a spanwise row of vortex-generator jets (VGJs) located at 60% chord on the suction surface. The purpose of the study is to document the effectiveness of VGJ flow control in high-speed compressible flow. The effect on shock-induced separation is assessed by Mach number distribution, wake loss surveys and shadowgraph. Pressure sensitive paint (PSP) is applied to understand the three dimensional flow and shock pattern developing from the interaction of the skewed jets and the main flow. Data show that with increasing blowing ratio, the losses are first decreased due to separation reduction, but losses connected to compressibility effects become stronger due to increased passage shock strength and jet orifice choking; therefore, the optimum blowing ratio is a tradeoff between these counteracting effects. The effect of added surface roughness on the uncontrolled flow and on flow control behavior is also investigated. At lower Mach number, turbulent separation develops on the rough surface and a different flow control performance is observed. Steady VGJs appear to have control authority even on a turbulent separation but higher blowing ratios are required compared to incompressible flow experiments reported elsewhere. Overall, the results show a high sensitivity of steady VGJs control performance and optimum blowing ratio to compressibility and surface roughness.

Controls for Plasma Spraying Based on Plasma Jet Stability Analysis

1998 ◽  
Author(s):  
L. Beall ◽  
Z. Duan ◽  
J. Schein ◽  
J. Heberlein ◽  
M. Stachowicz ◽  
...  
Keyword(s):  
Process Control ◽  
Plasma Spraying ◽  
High Speed ◽  
Small Degree ◽  
Negative Effects ◽  
Microphone Signal ◽  
Jet Length ◽  
Jet Stability ◽  
Control Scheme ◽  
Coating Characteristics

Abstract Despite the fact that plasma spraying has been a widely used technology over the past three decades, industries using this technology still need higher quality products. Presently, only a small degree of process control is used in most plasma spraying systems. Improved process control should lead to more consistent results and higher quality products. We discuss a relatively simple control scheme consisting of a microphone as a primary sensor and a fuzzy logic look-up model indicating the condition of the anode. Selected frequency peaks in the power spectrum of the microphone signal are analyzed online, and the results are correlated with an average jet length obtained from a series of high speed images. The jet length, in turn, is correlated with coating characteristics. A simple feedback control system is proposed which will counteract the negative effects of an eroded anode on coating quality.

scholarly journals A New Linear Motor Force Ripple Compensation Method Based on Inverse Model Iterative Learning and Robust Disturbance Observer

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-19
Author(s):  
Xuewei Fu ◽  
Xiaofeng Yang ◽  
Zhenyu Chen
Keyword(s):  
Iterative Learning Control ◽  
Disturbance Observer ◽  
Learning Control ◽  
Inverse Model ◽  
Iterative Learning ◽  
Compensation Method ◽  
Tracking Accuracy ◽  
Linear Motors ◽  
Learning Speed ◽  
Force Ripple

Permanent magnet linear motors (PMLMs) are gaining increasing interest in ultra-precision and long stroke motion stage, such as reticle and wafer stage of scanner for semiconductor lithography. However, the performances of PMLM are greatly affected by inherent force ripple. A number of compensation methods have been studied to solve its influence to the system precision. However, aiming at some application, the system characteristics limit the design of controller. In this paper, a new compensation strategy based on the inverse model iterative learning control and robust disturbance observer is proposed to suppress the influence of force ripple. The proposed compensation method makes fully use of not only achievable high tracking accuracy of the inverse model iterative learning control but also the higher robustness and better iterative learning speed by using robust disturbance observer. Simulation and experiments verify effectiveness and superiority of the proposed method.

scholarly journals Finite-Time Path Following Control of an Underactuated Marine Surface Vessel with Input and Output Constraints

2020 ◽  
Vol 10 (18) ◽  
pp. 6447
Author(s):  
Mingyu Fu ◽  
Lulu Wang
Keyword(s):  
Finite Time ◽  
Input Saturation ◽  
Path Following ◽  
Parametric Uncertainties ◽  
External Disturbances ◽  
Time Path ◽  
Path Following Control ◽  
Control Scheme ◽  
Marine Surface ◽  
Surface Vessel

This paper develops a finite-time path following control scheme for an underactuated marine surface vessel (MSV) with external disturbances, model parametric uncertainties, position constraint and input saturation. Initially, based on the time-varying barrier Lyapunov function (BLF), the finite-time line-of-sight (FT-LOS) guidance law is proposed to obtain the desired yaw angle and simultaneously constrain the position error of the underactuated MSV. Furthermore, the finite-time path following constraint controllers are designed to achieve tracking control in finite time. Additionally, considering the model parametric uncertainties and external disturbances, the finite-time disturbance observers are proposed to estimate the compound disturbance. For the sake of avoiding the input saturation and satisfying the requirements of finite-time convergence, the finite-time input saturation compensators were designed. The stability analysis shows that the proposed finite-time path following control scheme can strictly guarantee the constraint requirements of the position, and all error signals of the whole control system can converge into a small neighborhood around zero in finite time. Finally, comparative simulation results show the effectiveness and superiority of the proposed finite-time path following control scheme.

High Speed Transient Temperature Profile Control Using Adjoint-Based Optimal Control Scheme

2011 ◽  
Author(s):  
Satoru Ito ◽  
Yuji Suzuki
Keyword(s):  
Optimal Control ◽  
Temperature Profile ◽  
Active Layer ◽  
Laser Diode ◽  
High Speed ◽  
Transient Temperature ◽  
Control Input ◽  
Control Scheme ◽  
Profile Control ◽  
Optimal Control Scheme

Optimal control scheme for transient temperature profile inside electronic devices such as pulsed laser diode is developed based on the adjoint equation of one-dimensional heat conduction. Joule heating with a thin-film heater is employed as the control input in order to minimize temperature changes of a thin active layer embedded in a modeled laser diode. In numerical simulations assuming the light-emitting time period of 1 μs, temperature variation of the active layer is successfully suppressed by 80% with the heat input prior to the onset of the laser pulse. It is found that the Fourier number of the layer between the control heater and the active layer is the key parameter to minimize the temperature fluctuations. We also successfully demonstrate suppression of the temperature change in a MEMS-based experimental setup.

Design of a High-Speed Spherical Four-Bar Mechanism for Use in a Motion Common in Assembly Processes

2007 ◽  
Author(s):  
Andrew P. Murray ◽  
Franc¸ois Pierrot
Keyword(s):  
Sensitivity Analysis ◽  
High Speed ◽  
Mechanical Design ◽  
Degree Of Freedom ◽  
Kinematic Synthesis ◽  
Control Scheme ◽  
Smooth Motion ◽  
Spherical Mechanism

In this paper, we present the mechanical design of a spherical four-bar mechanism for performing a motion common in manufacturing and assembly processes. The mechanism is designed to create, in a single, smooth motion, the combined rotation of a body by 90 degrees about one axis with a 90 degree rotation about an axis perpendicular to the first. A spherical four-bar mechanism is pursued as the basis for the design because the reorientation is produced mechanically rather than via a control scheme typical when higher degree of freedom systems are utilized. The design initiates with the kinematic synthesis of the spherical mechanism to guide a body through two orientations. The next step in the design is to refine the spherical fourbar based on manufacturing and operational concerns. As one of the challenges of utilizing these four-bars is tuning the starting and ending angle for the mechanism’s motion, a sensitivity analysis is performed to gauge the needed accuracy. Finally, there are details and a discussion of the proposed mechanical design.

A Strictly Defined Orthogonal Global Task Coordinate Frame and its Contouring Control Application on Biaxial Systems

2019 ◽  
Author(s):  
Can Yang ◽  
Zheng Chen ◽  
Bin Yao ◽  
Bobo Helian
Keyword(s):  
High Speed ◽  
Order Approximation ◽  
Contour Error ◽  
Coordinate Frame ◽  
Robust Controller ◽  
Contouring Control ◽  
Modeling Uncertainties ◽  
False Position ◽  
First Order Approximation ◽  
Control Application

Abstract In this paper, a strictly defined new orthogonal global task coordinate frame (NGTCF) based on the false position method is proposed for precision contouring control of biaxial systems. In contrast to the existed global task coordinate frame (GTCF), the value of the normal coordinate in NGTCF directly represents the contour error, rather than the first-order approximation. Moreover, different from the conventional GTCF just suitable for contours with explicit shape functions, the proposed NGTCF can be utilized in various complex contours. The false position method is adopted to calculate the curve coordinates of actual points in NGTCF. Then an adaptive robust controller (ARC) is designed to deal with the effects of strong coupling of the system dynamics in the task space and modeling uncertainties. The proposed NGTCF-based ARC contouring control strategy is tested on a linear motor driven biaxial industrial gantry. Experiments under different contouring tasks with high-speed and large-curvature are conducted to verify the effectiveness of the proposed method, and the experimental results confirm that the excellent contouring performance of the proposed approach can be achieved.

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