Zhou Shichang

Mathematical Model and Numerical Simulation of the Electrode Hydraulic Servo Control System of a Vacuum Electric-Arc Furnace

The hydraulic servo control system is widely used in electrode control of electric-arc furnace. But the mathematical model and the dynamic performance of such a system are not researched in detail. In this papers by analyzing the dynamic performance of the electrode hydraulic servo control system, a mathematical model of 7th order for this system is established and its ramp-step response is calculated by numerical simulation.

Magnetosensitive Displacement Sensor - A Non-Contact Type Sensor

A sensor is proposed for measuring the displacement of a moving part in a hydraulic system. Magnetosensitive resistance is used as the sensing element; the displacement of the measured part is reflected by the variation of the magnetic field and sensed by a magnetosensitive resistance. The magnetosensitive element is a thin film resistance with strong magnetism. It is very sensitive not only to the variation of magnetic field intensity but also to the change of direction of magnetic field. It has a high sensitivity and a good temperature characteristic. The relationship between output voltage and temperature is linear making compensation easy.

The self-learning CMAC control of the oil temperature in hydraulic system

In view of the large time delay of the temperature control system of hydraulic system, a self-learning cerebellar model articulation controller (CMAC) algorithm is proposed to control the cooling system. The temperature control precision exceeds the Grade A of ISO standard (50/spl plusmn/1/spl deg/C) and reaches the level of 50/spl plusmn/0.5/spl deg/C. The cooling system is composed of digital and proportional controllers and in hybrid form. This can increase the control precision. Considering the speciality of the cooling system, an inverse dynamics model different from the one commonly used is established. The computing speed of the self-learning CMAC is fast and thus can be used online. Different learning rules are used for different error bands to meet the requirement on speed of response and steady state precision. The experimental result shows that the proposed self-learning CMAC control can be effectively used in the temperature control of hydraulic systems.