Automatic profiling machine is a movement system that has a high degree of parameter variation and high frequency of transient process, and it requires an accurate control in time. In this paper, the discrete model reference adaptive control system of automatic profiling machine is discussed. Firstly, the model of automatic profiling machine is presented according to the parameters of DC motor. Then the design of the discrete model reference adaptive control is proposed, and the control rules are proven. The results of simulation show that adaptive control system has favorable dynamic performances.
Automatic profiling machine is a movement system which has a high degree of parameter variation and high frequency of transient process, and it requires an accurate control in time. The traditional linear control methods, such as PID, cannot meet present needs or requirements of advanced performance. The adaptive control not only solves the problem that the control plant cannot be observed directly, but also improved the abilities of resisting interference [
The control system is double closedloop control system whose current loop is PI control and speed loop is MRAC. The DC motor parameters [
The parameters of DC motor.
Parameter  Unit  Value 

Rated voltage  V  100 
Rated current  A  6 
Rated speed  r/min  1000 
Motor constant  V/r/min  0.1 
Electromagnetic time constant  s  0.00246 
Mechanical time constant  s  0.078 
The difference equation of the plant is
The difference equation of the reference model is
The output error and its prediction are given by
The structure of the adaptive control system is shown in Figure
Block diagram of MRAC system.
From Figure
Introduc (
Subtract (
According to the Hyperstability theory, the discrete system control laws [
The prediction error can be gained:
Subtract (
The reference model takes the form as follows:
Make simulation according to the analysis above by SIMULINK. The structure of the adaptive control system is shown in Figure
Parameter values of MRAC system.
Parameter  Value  Parameter  Value 


0 

0 

0.1 

0.01 

1 

0 

3000 

0.01 

0 

0 

1 

0.1 
Simulation block diagram of MRAC system.
The simulation results are shown in Figures
Output figures of simulation.
Reference model
Control plant
Error figure
Output figure with interference signal.
Control plant
Interference signal
Error figure
Output figures with white noise.
The discrete model reference adaptive control system of automatic profiling machine is discussed in this paper. The results of simulation show that adaptive control system has favorable dynamic performance. The discrete design method is easy to realize by computer. The work in this paper will lay a foundation for the application of adaptive control in practice.
This paper was supported by the National Science and Technology Support Program Project (2009BAH41B05) and the Fundamental Research Funds for the Central Universities.