Authors:
Rastko R. Selmic,
Frank L. Lewis,
Volume: 1, Page 1742 Paper number 3101
Abstract:
Neural network compensation scheme is presented for the class of nonlinear
systems with backlash nonlinearity. The compensator uses the backstepping
technique with neural networks (NN) for inverting the backlash nonlinearity
in the feedforward path. Instead of a derivative, which cannot be implemented,
a filtered derivative is used. Full rigorous stability proofs are given
using filtered derivative. Compared with adaptive backstepping control
schemes, we do not require the unknown parameters to be linear parametrizable.
No regression matrices are needed. The technique provides a general
procedure for using NN to determine the dynamic preinverse of an invertible
dynamical system. A modified Hebbian algorithm is presented for NN
tuning which yields a stable closed-loop system. Using this method
yields a relatively simple adaptation structure and offers computational
advantages over gradient descent based algorithms.
Authors:
Chiang-Ju Chien,
Li-Chen Fu,
Volume: 1, Page 1748 Paper number 3102
Abstract:
In this paper, an iterative learning control using neural network design
is presented for robot manipulators with input disturbance and re-initialization
uncertainty. A sampled-data feedforward learning algorithm is designed
under a feedback configuration and a rigorous proof via a discrete
approach is given to study the learning performance. It is shown that
under a sufficient condition on the learning gain, convergence and
robustness of tracking error in the iteration domain can be guaranteed
at each sampling instant if sampling period is small enough. Since
the implementation of learning gain depends on the information of input-output
coupling matrix of robot manipulator, a neural network is proposed
to solve the implementation problem. A training procedure is applied
to estimate the robot manipulator by using only input-output data.
The neurons, equivalent to the premise and consequent parameters of
a fuzzy system, are tuned by gradient descent and least squares estimate.
This will give an initial setting of the neural-network based iterative
learning controller. During the control iterations, the neural network
can still be tuned for each iteration in order to improve the approximation
accuracy and increase the tracking speed.
Authors:
Russell Enns,
Jennie Si,
Volume: 1, Page 1754 Paper number 3103
Abstract:
In this paper we introduce a new neural learning control mechanism
for helicopter flight control design. The significance of our contribution
is twofold. First neural dynamic programming (NDP) is in its early
development stage and successful applications to date have been limited
to simple systems, typically those possessing only a single control
and a handful of states. With our industrial scale helicopter model,
we consider a very realistic class of complex design problem. To accommodate
such complex systems we introduce the concept of a trim network which
is seamlessly integrated into our NDP control structure and is trained
using our NDP control structure. Second, we introduce a new class
of design methodologies to the helicopter control system design community.
This approach is expected to be effective in dealing with real-time
learning applications such as reconfigurable control. The paper consists
of a comprehensive treatise of NDP and extensive simulation studies
of NDP designs for controlling an Apache helicopter. All of our designs
are tested using FLYRT, a sophisticated industry-scale non-linear validated
model of the Apache helicopter. Though illustrated for helicopters,
our NDP control system framework should be applicable to general control
systems.
Authors:
Shuzhi Sam Ge,
Tong-Heng Lee,
Jing Wang,
Volume: 1, Page 1760 Paper number 3104
Abstract:
In this paper, based on the dynamic LuGre friction model, adaptive
NN controllers are presented by using neural networks to parameterize
the unknown characteristic function or the unknown dynamic friction
bounding function respectively. Using Lyapunov synthesis, the adaptive
control algorithms are designed to achieve globally asymptotic tracking
of the desired trajectory and guarantee the boundedness of all the
signals in the closed-loop. Intensive simulations are carried out to
verify the effectiveness of the proposed methods.
Authors:
Gang Feng,
Volume: 1, Page 1766 Paper number 3105
Abstract:
This paper considers position control of a PM stepper motor. A new
control scheme is proposed based on a kind of exact linearization controller
and a neural network based compensating controller. This scheme takes
advantages of simplicity of the model based control approach and uses
the neural network controller to compensate for the motor modeling
uncertainties. The neural network is trained on line based on Lyapunov
theory and thus its convergence is guaranteed.
Authors:
Jin Wang,
Jie Huang,
Volume: 1, Page 1770 Paper number 3106
Abstract:
The problem of designing a control law to achieve asymptotic tracking
and disturbance rejection in a nonlinear plant where both the reference
and disturbance signals are generated by an exosystem is called nonlinear
output regulation problem. It is known that solvability of this problem
relies on the existence of a feedforward function defined by a set
of mixed nonlinear partial and algebraic equations called regulator
equations. Previous approaches to solving the output regulation problem
call for the solution of the regulator equations. However, solving
the regulator equations is difficult due to the nonlinearity and complexity.
This paper proposes a novel approximation approach to solving the output
regulation problem by directly approximating the feedforward function
using a class of artificial neural networks. Further, a control configuration
is developed that allows the reduction of the tracking error by the
on-line adjustment of the parameters of the neural networks. The major
advantages of our proposed approach over the previous approaches include
1) the precise knowledge of the plant is not needed, and 2) computation
complexity is significantly reduced. The effectiveness of our approach
are demonstrated by two well known nonlinear benchmark control problems
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