A Novel, Abstract Rotation-Based Fixed Point Transformation in Adaptive Control

Galambos, Péter; Tar, József K.; Györök, György; Serester, Andrea; Csandi, Bertalan

doi:10.1109/smc.2018.00441

Cited by 35 publications

(17 citation statements)

References 19 publications

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“…The function called "Robust Fixed Point Transformation" was the first example that was published in [21]. Later different functions were suggested and investigated via simulations in [23][24][25] that mean potential solutions. In the near future, experimental performance investigation of fixed point iteration based methods will hopefully be carried out by the help of the presented twin rotor test platform.…”

Section: Discussionmentioning

confidence: 99%

Experimental and Simulation-Based Performance Analysis of a Computed Torque Control (CTC) Method Running on a Double Rotor Aeromechanical Testbed

et al. 2021

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Concept of closed loop control appears in many fields of engineering sciences, where the output quantity of some physical system must be forced to follow some prescribed function over time, e.g., when a robotic arm endpoint must track a desired trajectory or path given as timed series of spatial coordinates. The classic approach for solving this kind of problem involves a PID compensation block, and the necessary input signal for keeping the controlled process in the vicinity of the desired trajectory is calculated as the weighted sum of momentary deviation, deviation integral, and deviation derivative relative to the reference path. However, despite the obvious advantages, practical usability, and simplicity of the PID controllers, their performance is limited when they are utilized for controlling nonlinear systems. Even with linear systems, their proper operation requires an accurate system model and precise tuning process for finding the best weight values for the proportional, integral, and derivative effects, and the planned closed loop behavior might change significantly as the parameters of the controlled plant change over time. In this article, a computed torque-based controller is presented, which has only one adjustable parameter ensuring precise trajectory tracking even with significantly alternated model constants. The practical usability of the offered algorithm is evaluated and verified by simulations and experiments performed on a simple mechanical bi-rotor testbed playing the role of controlled plant.

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Section: Discussionmentioning

confidence: 99%

Experimental and Simulation-Based Performance Analysis of a Computed Torque Control (CTC) Method Running on a Double Rotor Aeromechanical Testbed

et al. 2021

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“…For making it more easy to find an appropriate α, the linear iteration outlined in (31) was replaced by a non-linear one in ref. [66] in the following simple manner: by choosing a big value 0 < R ∈ R so that qReal ∈ R n , qDes ∈ R n , qDef ∈ R n R, these vectors were so augmented by the use of a "complementary, physically not interpreted dimension" that they obtained the common "augmented norm" R. Consequently, the A := [q Des ; D Des ], B := [q Real ; D Real ] and C := [q Def ; D Def ] ∈ R n+1 vectors can be rotated into each other in R n+1 , and it is easy to construct the orthogonal matrix that rotates B(i) to v Des (i + 1) so that the orthogonal subspace of these vectors remains invariant. By interpolating the angle of rotation by a factor λ a ∈ (0, 1), the physically interpreted projections of the vectors will not be completely identical: they will only approach each other.…”

Section: Fixed Point Iteration-based Adaptive Controlmentioning

confidence: 99%

Fractional order inspired iterative adaptive control

Varga,

Tar,

Horváth

2023

Robotica

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Although several studies have revealed that fractional order controllers usually outperform conventional integer-order control solutions, fractional order controllers are not yet widely applied in industrial applications due to their complex mathematical background. In this paper, further improvements of a simple weighted sum feedback design are introduced that imitates the behavior of a fractional order controller but is free from its various formal restrictions. The proposed control solution has the main characteristics of a fractional order controller, such as finite memory length, excellent transient response with no overshoot and robust behavior, but it is placed into a much simpler mathematical framework. In the current paper, a simple derivative term was incorporated in the design which made the controller’s output more stable by completely eliminating output chattering. The proposed control method was developed for a general second-order system. It was tested in a fixed point iteration-based adaptive control scenario, through simulations using a robotic example and on experimental basis as well, utilizing a simple one-degree-of-freedom electromechanical system. The presented experiments are the first systematic investigations of the fixed point iteration-based adaptive control method.

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“…In a special version of the fixed-point iteration-based adaptive control in [75] a transformation was needed that mapped the vector b ∈ R n into vector a ∈ R n so that normally a = b . Additionally, besides the exact transformation certain "interpolation" possibility was necessary for the control.…”

Section: The Model Structure the Activation Function And The Teaching Processmentioning

confidence: 99%

A Simple Soft Computing Structure for Modeling and Control

Redjimi

Tar

2021

Machines

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Using the interpolation/extrapolation skills of the core function of an iterative adaptive controller, a structurally simple single essential layer neural network-based topological structure is suggested with fast and explicit single-step teaching and data-retrieving abilities. Its operation does not assume massive parallelism, therefore it easily can be simulated by simple sequential program codes not needing sophisticated data synchronization mechanisms. It seems to be advantageous in approximate model-based common, robust, or adaptive controllers that can compensate for the effects of minor modeling imprecisions. In this structure a neuron can be in either a firing or a passive (i.e., producing zero output) state. In firing state its activation function realizes an abstract rotation that maps the desired kinematic data into the space of the necessary control forces. The activation function allows the use of a simple and fast incremental model modification for slowly varying dynamic models. Its operation is exemplified by numerical simulations for a van der Pol oscillator in free motion, and within a Computed Torque type control. To reveal the possibility for efficient model correction, a robust Variable Structure/Sliding Mode Controller is applied, too. The novel structure can be obtained by approximate experimental observations as e.g., the fuzzy models.

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A Novel, Abstract Rotation-Based Fixed Point Transformation in Adaptive Control

Cited by 35 publications

References 19 publications

Experimental and Simulation-Based Performance Analysis of a Computed Torque Control (CTC) Method Running on a Double Rotor Aeromechanical Testbed

Experimental and Simulation-Based Performance Analysis of a Computed Torque Control (CTC) Method Running on a Double Rotor Aeromechanical Testbed

Fractional order inspired iterative adaptive control

A Simple Soft Computing Structure for Modeling and Control

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