Control of an Isolated Table's Fluctuation Caused by Supplied Air Pressure Using a Voice Coil Motor

Mechanical Engineering Letters

2017

Self Cite

Pneumatic anti-vibration apparatus (AVA) has been used for suppression of vibration from floor in the field like semiconductor manufacturing. The compressed air supplied to the pneumatic AVA is generated by the air compressor. During the compression process of the air, the pressure of the compressed air varies. Consequently, the pressure variation changes the flow rate of the air supplied to the pneumatic AVA, which is called flow disturbance. Based on the internal model principle, the suppression of vibration of AVA due to flow disturbance has been confirmed by using Central Pattern Generator (CPG). Previous studies in the field of biology have confirmed the existence of a neuronal network that generates a walking rhythm in the spinal cord of an organism, and this is called CPG. Some researchers have applied CPG to such as walking of biped-robots. However, there are no applications using information inside CPG. This letter proposes using internal information in CPG as new method for further vibration suppression, compared with the conventional method. Specifically, this method makes use of outputs corresponding to differential and integral signals inside the CPG. It is shown the effectiveness of the proposed method by experimental results.

Section: Flow Disturbancementioning

confidence: 99%

“…This disturbance varies the flow rate of the compressed air sent to the AVA. This variation of flow rate is called flow disturbance and causes vibration of the AVA (Shirani and Wakui, 2010).…”

Section: Introductionmentioning

confidence: 99%

A trial of flow disturbance suppression for pneumatic anti-vibration apparatus using internal information in central pattern generator

Kashiwazaki

Mechanical Engineering Letters

2017

Self Cite

“…A pneumatic isolation table is mounted on air springs which are actively controlled by servo valves. During the compression process by the air compressor, the pressure of the compressed air varies, which causes the variation of the supplied air known as flow disturbance (5,6) to the air spring. The air compressor periodically compresses the air.…”

Section: Introductionmentioning

confidence: 99%

“…Previously, we used two feedforward control schemes based on the measured supplied air pressure signal. One scheme employed an air spring whereas the other used a voice coil motor (VCM) as the actuators (5,6) . The supplied air pressure was measured by an expensive and sophisticated pressure sensor for feedforward control.…”

Section: Introductionmentioning

confidence: 99%

Flow Disturbance Compensation Based on Off-Line Estimated Signal for a Pneumatic Isolation Table

Shirani

Nakamura

2013

JAMDSM

Self Cite

The flow disturbance to a pneumatic vibration isolation table causes periodic fluctuation of the table. In current study, one cycle of flow disturbance is estimated offline using a disturbance observer. The time series data of one cycle estimated disturbance is then stored in the memory of digital signal processor. The program codes are prepared which can detect every cycle of the flow disturbance based on the threshold of table position. The estimated signal is then repeatedly injected from the memory through a compensator to the servo valve to suppress table fluctuation due to periodic actual flow disturbance. The effectiveness of this method is demonstrated by experimental results.

“…However, this switching of the feedforward controller also causes the fluctuation of the table. In order to suppress the fluctuation of the table, we employed a feedback damping loop (1) . However, the damping loop control scheme used in reference (1) cannot control the fluctuation of the table at different timing of switching.…”

Section: Introductionmentioning

confidence: 99%

Suppression of Isolation Table's Fluctuation Due to Switching of Feedforward Controller

Shirani

Nakamura

2011

JAMDSM

Self Cite

To avoid a longer settling time of an isolation table, switching of the feedforward controller which is used for the control of supplied air's disturbances, is needed after starting and prior to stopping the table. However, this switching also causes the fluctuation of the table. In order to suppress the fluctuation of the table caused by switching, this study uses a difference operator before the feedforward compensator and the combination of feedforward and feedback loops. The effectiveness of this method is experimentally demonstrated.