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Transient Enhancement in Add-On Feedforward Algorithms for High-Performance Mechatronic Systems
Abstract
In this paper, we analyze the problem of control injection in feedforward compensation, and discuss the transient enhancement in add-on feedforward algorithms. In contrast to the common feedforward injection at the plant input, the updated reference feedforward design is discussed with the advantage of accelerated transient. Such a configuration also brings convenience from the viewpoints of filter implementation and uniformed design in industrial mass production. Two implementation examples are provided from advanced manufacturing and precision motion control.
... Literature [1][2][3][4][5][6][7][8][9][10][11] and laboratory studies as well as experimental verification determine the possibilities for analytical modeling of the dynamics of FANUC M-430iA / 4FH in the following sequence. The schematic diagram (Fig. 4) of the electric drive (uniform on all axes of the 5-DOF manipulator) with a DC motor with permanent magnet is considered, where the following markings are used: (4) and (5), we reach (6), where s T is the time constant of the motor and sm K is the gain of the motor. ...
In this work, you can find the results from the description and modeling of the robotic
manipulator FANUC M-430iA / 4FH. The basic values that determine the performance
of the robot are tested and analyzed. An analytical model was developed on the basis of which it’s temporal and frequency characteristics are illustrated in the absence and availability of maximum mechanical load of the working spherical wrist
... Step The simulation results Fig.3 y Fig.6 confirm the reaching of the desired quality of the system according to the synthesis criterion const V (boundary aperiodic transition process) (7) for optimization, but also show a significant influence in changing the order of the controlled object as a result of the multiplicative disturbance load impact M 9 in "with max load an wrist" mode. To overcome this operational dependency, in the paper is proposes to design a robust position control system [15][16][17] 3. Robust DRC position control system for 5-DOF FANUC M-430iA / 4FH industrial robotic manipulator In contrast to the discussed (7), Fig.2 classical system with PID-regulators (symbolically reflected in Fig.7, where i R * R { ) and from the known ones till now [1][2][3][4][5][6][7][8][9][10][11][12][13][14], a robust DRC position control system is offered ...
This paper offers the results of the control capabilities of the FANUC M-430iA / 4FH robotic manipulator. Classical and DRC robotic position control systems have been synthesized. Both systems are modelled. Their quality has been researched and comparatively analysed in unloaded, maximum loaded and in operation vibration working modes.
In Proc. of TechSys 2020, IOP Conf. Series: Materials Science and Engineering 878 (2020) 012007, IOP Publishing, doi:10.1088/1757-899X/878/1/012007, pp. 1-10
https://iopscience.iop.org/article/10.1088/1757-899X/878/1/012007/meta
... Step The simulation results Fig.3 y Fig.6 confirm the reaching of the desired quality of the system according to the synthesis criterion const V (boundary aperiodic transition process) (7) for optimization, but also show a significant influence in changing the order of the controlled object as a result of the multiplicative disturbance load impact M 9 in "with max load an wrist" mode. To overcome this operational dependency, in the paper is proposes to design a robust position control system [15][16][17] 3. Robust DRC position control system for 5-DOF FANUC M-430iA / 4FH industrial robotic manipulator In contrast to the discussed (7), Fig.2 classical system with PID-regulators (symbolically reflected in Fig.7, where i R * R { ) and from the known ones till now [1][2][3][4][5][6][7][8][9][10][11][12][13][14], a robust DRC position control system is offered ...
This paper offers the results of the control capabilities of the FANUC M-430iA / 4FH robotic manipulator. Classical and DRC robotic position control systems have been synthesized. Both systems are modelled. Their quality has been researched and comparatively analysed in unloaded, maximum loaded and in operation vibration working modes
... Literature [1][2][3][4][5][6][7][8][9][10][11] and laboratory studies as well as experimental verification determine the possibilities for analytical modeling of the dynamics of FANUC M-430iA / 4FH in the following sequence. The schematic diagram (Fig. 4) of the electric drive (uniform on all axes of the 5-DOF manipulator) with a DC motor with permanent magnet is considered, where the following markings are used: (4) and (5), we reach (6), where s T is the time constant of the motor and sm K is the gain of the motor. ...
In this work, you can find the results from the description and modeling of the robotic manipulator FANUC M-430iA / 4FH. The basic values that determine the performance of the robot are tested and analyzed. An analytical model was developed on the basis of which it’s temporal and frequency characteristics are illustrated in the absence and availability of maximum mechanical load of the working spherical wrist.
A digital feedforward control algorithm for tracking desired time varying signals is presented. The feedforward controller cancels all the closed-loop poles and cancellable closed-loop zeros. For uncancelled zeros, which include zeros outside the unit circle, the feedforward controller cancels the phase shift induced by them. The phase cancellation assures that the frequency response between the desired output and actual output exhibits zero phase shift for all the frequencies. The algorithm is particularly suited to the general motion control problems including robotic arms and positioning tables. A typical motion control problem is used to show the effectiveness of the proposed feedforward controller.
This article surveyed the major results in iterative learning control (ILC) analysis and design over the past two decades. Problems in stability, performance, learning transient behavior, and robustness were discussed along with four design techniques that have emerged as among the most popular. The content of this survey was selected to provide the reader with a broad perspective of the important ideas, potential, and limitations of ILC. Indeed, the maturing field of ILC includes many results and learning algorithms beyond the scope of this survey. Though beginning its third decade of active research, the field of ILC shows no sign of slowing down.
Sufficient conditions for the robustness and convergence of P-type
learning control algorithms for a class of time-varying, nonlinear
systems are presented. The authors prove the uniform boundedness of the
system state and the input control with respect to the existence of
errors of initialization, measurement noises, and fluctuations of system
dynamics. Furthermore, the system output converges uniformly to the
desired one in absence of all disturbances. Finally, specialization of
the results to linear systems are presented
An algorithm for Iterative Learning Control is developed based on an optimization principle which has been used previously to derive gradient type algorithms. The new algorithm has numerous benefits which include realization in terms of Riccati feedback and feedforward components. This realization also has the advantage of implicitly ensuring automatic step size selection and hence guaranteeing convergence without the need for empirical choice of parameters. The algorithm is expressed as a very general norm optimization problem in a Hilbert space setting and hence, in principle, can be used for both continuous and discrete time systems. A basic relationship with almost singular optimal control is outlined. The theoretical results are illustrated by simulation studies which highlight the dependence of the speed of convergence on parameters chosen to represent the norm of the signals appearing in the optimization problem. Contents 1 Introduction 1 2 Norm Optimal Iterative Learning Cont...
This paper presents an H∞-based design technique for the synthesis of higher-order iterative learning controllers (ILCs) for plants subject to iteration-domain input/output disturbances and plant model uncertainty. Formulating the higher-order ILC problem into a high-dimensional multivariable discrete-time system framework, it is shown how the addition of input/output disturbances and plant model uncertainty to the ILC problem can be cast as an H∞-norm minimization problem. The distinctive feature of this formulation is to consider the uncertainty as arising in the iteration domain rather than the time domain. An algebraic approach to solving the problem in this framework is presented, resulting in a sub-optimal controller that can achieve both stability and robust performance. The key observation is that H∞ synthesis can be used for higher-order ILC design to achieve a reliable performance in the presence of iteration-varying external disturbances and model uncertainty. Copyright © 2007 John Wiley & Sons, Ltd.
This paper presents a concise tutorial on iterative learning control (ILC) with an illustrative example. The authors' view of the "big picture" of ILC research is presented with the goal of pinpointing and stimulating future research efforts in the field
This paper considers two novel controller synthesis methodologies using a feedforward control structure for performing concentric self-servo track writing in hard disk drives. In the first methodology, it is assumed that a conventional causal track-following controller has been designed and a non-causal feedforward controller, which utilizes the stored error signal from writing the previous track, is designed using standard H ∞ control synthesis techniques, in order to prevent the track errors from propagating and to achieve good disturbance attenuation. In the second methodology, both the track-following feedback controller and the feedforward controller are simultaneously designed via a mixed H 2/ H ∞ control scheme, which involves the solution of a set of linear matrix inequalities and achieves good disturbance attenuation while preventing the propagation of track errors from the previous tracks. Simulation results confirm that the two proposed control synthesis methodologies prevent error propagation from the previously written tracks and significantly improve concentric self-servo track writing performance.
This paper applies the modified adaptive feedforward compensation
(AFC) scheme to the dual stage servo system for the cancellation of
repeatable runout (RRO) and nonrepeatable runout (NRRO). It shows that
runout can be effectively compensated or attenuated by assigning runout
components to VCM actuator and microactuator properly
This paper proposes an analytical two-degree-of-freedom control scheme for open-loop unstable processes with time delay, which leads to the remarkable improvement of regulatory capacity for both of reference input tracking and load disturbance rejection. Firstly a conventional proportional or plus derivative controller is deliberately employed for stabilizing the setpoint response. Then the setpoint tracking controller is analytically derived in terms of the integral-squared-error (ISE) performance specification. By proposing the desired closed-loop complementary sensitivity function for rejecting load disturbances, the corresponding controller, i.e. disturbance estimator, is inversely figured out. Hence the nominal setpoint response is decoupled from the load disturbance response by virtue of the open-loop control manner for the setpoint tracking. In consequence, both of them can be optimized simultaneously and separately. At the same time, robust stability analysis for the proposed control structure is provided in the presence of the process multiplicative uncertainty. Accordingly the on-line tuning rule for the single adjustable parameter of each controller is suggested to cope with the process unmodeled dynamics in practice. Finally, several illustrative examples are included to demonstrate the superiority of the proposed method.
With more density of data on magnetic disk drives, additional precise position control of the read/write head is needed. This thesis discusses two separate algorithms, acceleration feedforward control and a disturbance observer which does not require an external sensor but that can be used in the presence of internal and external disturbances. Photocopy. Thesis (Ph. D.)--University of California at Berkeley, 1997. Includes bibliographical references (p. 85-92).
A two-degree-of freedom (2 DOF) control structure is proposed for
read/write head servo systems of hard disk drives (HDDs). This structure
is applied to both track seeking and track following, and makes mode
switches found in conventional HDD servo systems unnecessary. Two
innovative features introduced in the paper are: 1) a new method for
generating the reference signal for track seeking and 2) two robust
feedback control schemes for rejection of disturbances; one scheme uses
a disturbance observer (DOB), and the other uses adaptive robust control
(ARC). Simulation results show that the 2 DOF structure with ARC
provides better performance than either the conventional servo system
with mode switches or the 2 DOF structure with DOB. Experimental results
show the advantage of the new reference generation method and the use of
the DOB-based robust controller
Control engineers often design feedback control systems for inherently unstable systems, to keep them operating safely. In such cases, there are fundamental limitations on the achievable sensitivity function. The article discusses the potentially serious consequences of sensitivity constraints, input saturation, and instability. Inadequacies of control systems in such cases have led to deaths.
In this note, we study linear time-invariant multivariable systems with two-degree-of-freedom compensators. First, we give a new parametrization of all stabilizing compensators from the viewpoint of independent design of transfer function and robustness property. Second, utilizing this parametrization, we solve a general robust tracking problem including the case of nonsquare plants, and show that "tracking" and "robustness" can be independently specified in two-degree-of-freedom control systems.
The paper investigates the generation of harmonics in adaptive
feedforward cancellation schemes. Specifically, it is shown that an
algorithm designed to reject a certain number of frequency components
may in fact be capable of reducing higher-order harmonics as well. This
effect originates in the time-variation of the adaptive parameters. A
consequence is that the adaptive system may perform better than the
algorithm with the fixed, ideal parameters. Surprisingly, the response
to higher-order harmonics can be calculated precisely, using a Laplace
transform analysis. The origin of the numerical procedure is in the
equivalence between the adaptive feedforward cancellation scheme and a
control scheme based on the internal model principle. The implication of
the results on design and implementation issues is discussed
Fundamental issues in iterative learning controller design: Convergence, robustness, and steady state performance
- S Mishra