Feedforward Control of Single-Link Flexible Manipulators by Discrete Model Inversion

1999 ◽  
Vol 121 (4) ◽  
pp. 713-721 ◽  
Author(s):  
V. Feliu ◽  
K. S. Rattan
Keyword(s):  
Transfer Function ◽  
Feedforward Control ◽  
Point Of View ◽  
Model Inversion ◽  
Single Link ◽  
Feedforward Controller ◽  
Tip Position ◽  
Flexible Arms ◽  
System Transfer Function ◽  
General Method

The design of feedforward controllers to control the position of single-link flexible arms is developed in this paper. The objective is to drive the tip position along a commanded trajectory without any oscillations at the tip. The method is based on the well-known dynamics model inversion technique. Since the controllers are implemented on a computer, the dynamic inversion of the single-link flexible arm is studied from a discrete point of view. A general method to obtain a feedforward controller is developed, even in the case when the system transfer function is of nonminimum phase. The method is general in the sense that it removes oscillation in the arm with any number of vibration modes. A method to modify the transfer function of these controllers to improve the robustness is also proposed in this paper. It is shown that the input preshaping scheme developed by Singer and Seering is a special case of this method. The design technique is illustrated with numerical examples and a comparison with the input preshaping method is carried out.

Design of Trajectories With Physical Constraints for Very Lightweight Single Link Flexible Arms

2006 ◽  
Author(s):  
Francisco Ramos ◽  
Vicente Feliu ◽  
Ismael Payo
Keyword(s):  
Design Process ◽  
Internal Control ◽  
Elastic Limit ◽  
Feedforward Control ◽  
Objective Method ◽  
Maximum Deflection ◽  
Robotic Arms ◽  
Physical Constraints ◽  
Single Link ◽  
Flexible Arms

This communication deals with feedforward control of light, flexible robotic arms. In particular we develop a new, objective method to design a family of trajectories that can be used as modified inputs which cancel the tip vibrations during the robot manoeuvres. This method takes into account the constraints encountered in real actuators (motors), such as a maximum motor torque, and those due to the mechanical limits of the link, such as the maximum deflection before reaching the elastic limit of the link. Parameters of the internal control of the actuators are also derived from the design process, gaining the fastest performance without saturating the motor. Lastly, we show some experimental results which clearly demonstrate the benefits of the new trajectories by comparing them to a linear one.

An enhanced feedback-feedforward control scheme for process industries

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Manish Yadav ◽  
Hirenkumar G. Patel
Keyword(s):  
Transfer Function ◽  
Disturbance Rejection ◽  
Dead Time ◽  
Feedforward Control ◽  
Absolute Error ◽  
Industrial Applications ◽  
Process Industries ◽  
Control Scheme ◽  
Feedforward Controller ◽  
Bode’S Ideal Transfer Function

Abstract In this article, a unified control scheme is proposed for dead-time compensation and disturbance rejection via feedback and feedforward controller. The objectives of this work are suggested in two folds, first tuning of fractional order feedback controller via delayed Bode’s ideal transfer function instead of conventional Bode’s ideal transfer function with the benefits of dead time compensator and second feedforward controller for disturbance rejection. An existing method is utilized for comparison with the proposed scheme. To examine the efficacy of the proposed method robustness test is also carried out via sensitivity analysis. For quantifiable evaluation of the proposed scheme Integral Absolute Error (IAE) and Integral Square Error (ISE) are utilized. For the usefulness of the proposed scheme, two practical problems are demonstrated in this paper. The limpidity and instinctive appeal of the proposed scheme make it beautiful for industrial applications.

Modeling and Control of Single-Link Flexible Arms With Lumped Masses

1992 ◽  
Vol 114 (1) ◽  
pp. 59-69 ◽  
Author(s):  
V. Feliu ◽  
K. S. Rattan ◽  
H. B. Brown
Keyword(s):  
Control Method ◽  
Flexible Beam ◽  
Outer Loop ◽  
Modeling And Control ◽  
Control Scheme ◽  
Single Link ◽  
Tip Position ◽  
Flexible Arms ◽  
Lumped Masses ◽  
And Control

This paper deals with the modeling and control of a special class of single-link flexible arms. These arms consist of flexible massless structures having some masses concentrated at certain points of the beam. In this paper, the dynamic model of such flexible arms is developed and some of the control properties are deduced. A robust control scheme to remove the effects of friction in the joins is proposed. The control scheme consists of two nested feedback loops, an inner loop to control the position of the motor and an outer loop to control the tip position. The inner loop is described in other publications. A simple feedforward-feedback controller is designed for the outer loop to drive the beam accurately along a desired trajectory. Effects of the changes in the tip’s mass are studied. This modeling and control method is then generalized to the distributed-mass flexible beam case. Finally, experimental results are presented.

High-Speed End Milling Using a Feedforward Control Architecture

1996 ◽  
Vol 118 (2) ◽  
pp. 178-187 ◽  
Author(s):  
E. D. Tung ◽  
M. Tomizuka ◽  
Y. Urushisaki
Keyword(s):  
High Speed ◽  
Feedforward Control ◽  
End Milling ◽  
Phase Error ◽  
Cutting Speed ◽  
Frequency Domain Analysis ◽  
Maximum Speed ◽  
Drive Control ◽  
Machining Errors ◽  
Feedforward Controller

Experiments are performed for end milling aluminum at 15,000 RPM spindle speed (1,508 m/min cutting speed) and up to 3 m/min table feedrate using an experimental machine tool control system. A digital feedforward controller for feed drive control incorporates the Zero Phase Error Tracking Controller (ZPETC) and feedforward friction compensation. The controller achieves near-perfect (±3 μm) tracking over a 26 mm trajectory with a maximum speed of 2 m/min. The maximum contouring error for a 26 mm diameter circle at this speed is less than 4 μm. Tracking and contouring experiments are conducted for table feedrates as high as 10 m/min. Frequency domain analysis demonstrates that the feedforward controller achieves a bandwidth of 10 Hz without phase distortion. In a direct comparison of accuracy, the machining errors in specimens produced by the experimental controller were up to 20 times smaller than the errors in specimens machined by an industrial CNC.

scholarly journals Pressure Based Lift Estimation and its Application to Feedforward Load Control employing Trailing Edge Flaps

2020 ◽  
Author(s):  
Sirko Bartholomay ◽  
Tom T. B. Wester ◽  
Sebastian Perez-Becker ◽  
Simon Konze ◽  
Christian Menzel ◽  
...  
Keyword(s):  
Surface Pressure ◽  
Feedforward Control ◽  
Force Balance ◽  
Estimation Methods ◽  
Load Control ◽  
Trailing Edge ◽  
Trailing Edge Flaps ◽  
Feedforward Controller ◽  
Trailing Edge Flap ◽  
C 30

Abstract. This experimental load control study presents results of an active trailing edge flap feedforward controller for wind turbine applications. The controller input is derived from pressure based lift estimation methods that rely either on a quasi-steady method, based on a three-hole probe, or on an unsteady method that is based on three selected surface pressure ports. Furthermore, a standard feedback controller, based on force balance measurements, is compared to the feedforward control. A Clark-Y airfoil is employed for the wing that is equipped with a trailing edge flap of x/c = 30 % chordwise extension. Inflow disturbances are created by a two-dimensional active grid. The Reynolds number is Re = 290,000 and reduced frequencies of k = 0.07 up to k = 0.32 are analyzed. Within the first part of the paper, the lift estimation methods are compared. The surface pressure based method shows generally more accurate results whereas the three-hole probe estimate overpredicts the lift amplitudes with increasing frequencies. Nonetheless, employing the latter as input to the feedforward controller is more promising as a beneficial phase lead is introduced by this method. A successful load alleviation was achieved up to reduced frequencies of k = 0.192.

Performance Evaluation of Multicast Overlay Routing Protocols

2012 ◽  
Vol 17 (1-2) ◽  
pp. 19-31
Author(s):  
Krzysztof Stachowiak ◽  
Tytus Pawlak ◽  
Maciej Piechowiak
Keyword(s):  
Group Communication ◽  
Evaluation Criteria ◽  
Point Of View ◽  
Multicast Communication ◽  
Application Layer ◽  
Communication Structure ◽  
Resources Management ◽  
Overlay Routing ◽  
Single Link ◽  
Overlay Approach

Abstract For almost three decades the multicast communication has been a subject of a dynamic research. It came to the world of the packet switching networks rather late and still has not become a fist class citizen of the Internet, yet the demand for such services is growing and thus the relevant technologies evolve persistently providing increasing quality and availability of the means of the group communication. The overlay approach to the multicast is an application layer realization which came to life due to certain deficiencies at the lower layers. In general the gain from using multicast for group communication instead of duplicated unicast links is that we avoid sending the same data many times through a single link. Such gain may be achieved wit the use of the router level mulitcast solution. The overlay solutions tend to approach his level of efficiency with a different degree of success. Therefore one of the main characteristics that is interesting when evaluating a particular overlay protocol is how well does it achieve the aforementioned gain. There are several metrics that allow for objective comparison of protocols in this regard. However this is not the only point of view to provide a valuable evaluation of the multicast overlay solutions. One of the important aspects of the modern group communication such as the IPTV or teleconferencing is the dynamic nature of the users’ participation. A particular group may be joined and left by multiple users at a very frequent rate which is critical to the resources management as well as to maintaining the integrity of the abstract communication structure, e.g. a tree spanning all the participants. In such case two major classes of the evaluation criteria emerge: the statical and the dynamical ones. They’re both very important and interdependent, however the means to measure them may differ significantly. In this article a wide variety of the multicast overlay protocols have been analysed and two of them have been chosen to be compared. The stress of the evaluation has been put on the dynamic aspects of the multicast overlay protocols operation.

Study on the Effect of Link Flexibility on Tip Position of a Single Link Robotic Arm

2021 ◽  
pp. 142-151
Author(s):  
E. Madhusudan Raju ◽  
L. Siva Rama Krishna ◽  
Y. Sharath Chandra Mouli ◽  
V. Nageswara Rao
Keyword(s):  
Robotic Arm ◽  
Single Link ◽  
Link Flexibility ◽  
Tip Position
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