Speed control system and design of resonant system with disturbance observer

1996 ◽  
Vol 116 (4) ◽  
pp. 75-84 ◽  
Author(s):  
Shigeo Morimoto ◽  
Hiroyuki Kameyama ◽  
Yoji Takeda
Keyword(s):  
Control System ◽  
Disturbance Observer ◽  
Speed Control ◽  
Resonant System ◽  
Speed Control System

Evaluation of Rotational Speed Control System for Water Driven Spindle With Disturbance Observer

2015 ◽  
Author(s):  
Akio Hayashi ◽  
Yohichi Nakao
Keyword(s):  
Control System ◽  
Rotational Speed ◽  
Disturbance Observer ◽  
Speed Control ◽  
Precision Machining ◽  
Feedback Control System ◽  
Speed Control System ◽  
Ultra Precision ◽  
Rotational Speed Control ◽  
The Mathematical Model

In ultra-precision machining to produce various precision products such as lenses or mirrors, the single-point diamond cutting is mainly carried out to achieve the high accuracy and high quality machined surfaces. Thus, the precise rotation accuracy is required to the spindle of the ultra-precision machining tool. The water driven spindle had been developed for the precision machining tool spindle. This spindle is driven by the torque of water flow power. Then, the rotational speed can be controlled by supplied flow rate of water. However, the rotational spindle speed during cutting operation is changed due to the influence of the cutting forces during the machining processes. The change in the rotational speed causes the change in the cutting speed, as a result, it degrades the machined surface quality as well. In order to reveal and reduce the influence of this phenomenon, the mathematical model of the rotational speed control system for water driven spindle was derived. This rotational speed control system consists of the water driven spindle and the flow control valve. From the simulation results using a derived transfer function of the rotational speed control system, it is clarified that the rotational speed changes depending on the external load torque. Then, based on the mathematical model, the feedback rotational speed control system with a conventional P-I controller is designed. The effectiveness of the proposed feedback control system is verified by the turning tests. Furthermore, a disturbance observer to minimize the influence of cutting forces on the rotational speed was added to the feedback control system. As a result, this paper shows the performance of the rotational speed control system.

Angular Position Control of Fluid-Driven Bi-Directional Motor

2010 ◽  
Vol 224 (11) ◽  
pp. 2350-2362 ◽  
Author(s):  
Y Nakao ◽  
M Ishikawa
Keyword(s):  
Control System ◽  
Rotational Speed ◽  
Disturbance Observer ◽  
Position Control ◽  
Angular Position ◽  
Speed Control ◽  
Load Torque ◽  
Speed Control System ◽  
Rotational Speed Control ◽  
Position Control System

This paper describes the design of a rotational speed-control system and an angular position-control system for a fluid-driven bi-directional motor. The fluid-driven bi-directional motor has a driving principle similar to that of the fluid-driven spindle, which is designed for use in ultra-precision machine tools. The fluid-driven bi-directional motor was designed so that it is driven by low viscosity oil flow power. In this paper, the rotational speed controller for the motor is first discussed. In order to reduce the influence of external load torque on the rotational speed, a conventional disturbance observer is combined with the rotational speed-control system. The angular position-control system, which possesses the rotational speed feedback loop with the disturbance observer in the angular position feedback loop, is then discussed. The designed rotational speed and angular position-control systems are conventional I—P control and proportional control systems, respectively. The performance of the designed rotational speed-control system and the angular position-control system is studied via simulations and experiments. The performance of the designed control system is tested by the step response method as well as by the frequency response method, respectively. The simulation and experimental results show that the rotational speed and the angular position of the motor can be controlled by the rotational speed controller and angular position controller, respectively. In addition, the influence of the external load torque acting on the motor is successfully compensated for by means of the disturbance observer. The experimental result shows that the designed angular position-control system suppresses the steady-state positioning error to less than 0.02°, even if external constant load torque acts on the motor.

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