Model Verification and Design of Speed Control System of Water Driven Stage

2011 ◽  
Author(s):  
Yohichi Nakao ◽  
Toshiaki Sano ◽  
Midori Nagashima ◽  
Kenji Suzuki
Keyword(s):  
Control System ◽  
Control Valve ◽  
Speed Control ◽  
Diamond Turning ◽  
Model Verification ◽  
Flow Control Valve ◽  
Piston Cylinder ◽  
Fine Diamond ◽  
Speed Control System ◽  
Ultra Precision

The present paper describes a design of speed control system of the water driven stage that has been developed for a feed table of an ultra-precision machine tool. The stage has a piston-cylinder mechanism to drive a table of the stage. Since the piston-cylinder mechanism is used, the flow rate supplied to the piston-cylinder controls the speed of the table. For diamond turning applications, the constant feed motion of the stage is highly desirable in order for obtaining fine diamond-turned surfaces. In the present paper, mathematical models of the water driven stage and a flow control valve are introduced. Based on the derived models, a conventional P-I control system is then designed in order to achieve desired control performances, aiming no steady-state error and minimized extraneous disturbance effects on the response. Performances of the designed controller are studied through experiments and simulations.

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.

Design of Rotary-Type Flow Control Valve for Control of Water-Driven Spindle

2010 ◽  
Author(s):  
Yohichi Nakao ◽  
Hajime Niimiya ◽  
Takuya Obayashi
Keyword(s):  
Mathematical Model ◽  
Control System ◽  
Flow Control ◽  
Mathematical Models ◽  
Rotational Speed ◽  
Control Valve ◽  
Diamond Turning ◽  
Flow Control Valve ◽  
Type Flow ◽  
Rotary Type

Water-driven spindle was developed for producing small and precise parts by the diamond turning processes. Rotational speed of the spindle can be controlled by the flowrate supplied to the spindle. The paper describes a newly developed rotary-type flow control valve that is designed for controlling rotational speed of the water-driven spindle. In particular, the paper focuses on the establishment of the mathematical model capable of representing the characteristics of the open loop control system composed of the pump, flow control valve and spindle. Mathematical models are then derived so that a feedback control system can be designed using the models. Performances of the flow control valve and the spindle are examined through simulation as well as experiments. It is then verified that the derived mathematical models are capable of representing the performance of the system. In addition, the required positioning accuracy of valve rotation for achieving desired control of the rotational speed of the spindle is considered based on the derived linearized mathematical model.

Research on the Constant Speed Control System of Hydraulic Motor Under Variable Flow-Rate Input Based on Dual-PID Method

2013 ◽  
Author(s):  
Huang Ruijia ◽  
Shi Guanglin
Keyword(s):  
Control System ◽  
Flow Rate ◽  
Control Valve ◽  
Speed Control ◽  
Constant Speed ◽  
Flow Control Valve ◽  
Hydraulic Motor ◽  
Hydraulic Pump ◽  
Constant Frequency ◽  
Variable Displacement

With the development and application of wind power generation and wave power generation, the hydraulic pump-motor control system has a unique effect on power conversion and constant speed driving of power generator. In this situation, the hydraulic pump-motor control system is required that the output speed of the hydraulic motor must be constant when the flow-rate input is randomly varied. Therefore, the power generator driven by the hydraulic motor can maintain constant speed and generate constant frequency electricity power. Considering the particular requirement mentioned above, this paper proposes a stratified-adjustment closed-loop speed control system which is rough-tuned by a variable-displacement motor and fine-tuned by a bypass proportional flow control valve and a control strategy based on dual-PID method. When the flow-rate from the hydraulic pump is randomly varied, the displacement of the variable-displacement motor and the opening of the bypass proportional flow control valve are stratified adjusting by a dual-PID controller, so that the output speed of the variable-displacement motor can maintain constant despite the flow-rate input varying. The simulation and the experiment show that the dual-PID stratified algorithm is effective for constant speed control of hydraulic motor under variable flow-rate input, and it fulfills the requirement of generating constant frequency electricity power.

Digital DC Speed Control System in Mine Hoist Application

2011 ◽  
Vol 219-220 ◽  
pp. 1017-1021
Author(s):  
Rui He ◽  
Yun Ping Ge
Keyword(s):  
Control System ◽  
Closed Loop ◽  
Speed Control ◽  
Closed Loop System ◽  
Pi Regulator ◽  
Control Precision ◽  
Speed Control System ◽  
Digital Trigger ◽  
Mine Hoist ◽  
Work Stability

Mine hoist shoulder important transport tasks. Through the analysis of the main circuit of mine hoist, this paper studies out ASCS digital DC speed control system whose core is microprocessor and whose hardware part constitutes digital trigger and double closed loop system. The software part not only achieves the system's digital PI regulator, logic switching, digital trigger phase shift, pulse channel selection and pulse width setting, but also realizes the systematic detection, monitoring, fault diagnosis, which improves the control precision and work stability of the system.

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