Vibes controlled actively

Problem: by minimising structure-borne vibration created by high dynamic forces produced during an acceleration or deceleration of a moving mass within the machine. Using conventional air springs with some kind of electro-pneumatic levelling system is often not enough. Solution: German technology firm Bilz has developed an electro-pneumatic Active Isolation System (AIS). The system consists of a PLC, CAN-Bus, 16-bit controllers, six high-speed electro-pneumatic servo valves and air springs. AIS can be controlled in real time and has six degrees of freedom, making it ideal for most sensitive machining or inspection applications. The16-bit controller can be mounted directly to the air spring itself or to the machine, in the same direction as the isolator motion. Located inside the 16-bit controller is a microprocessor, a position sensor, an acceleration sensor and an air pressure sensor. The signals from each of these sensors are sampled at the rate of 4kHz. The result is very efficient, real time control without the need for feedforward signals. The controllers are connected by a CAN-Bus to the PLC, which can be connected to a PC. Two different modes of operation can be selected by using a digital I/O. You can even program the software, WinSNI-Software, for setting up and optimising the AIS and for providing system diagnostics. Lee Shorrock, engineering director at Hinckley-based firm PES UK (the sole UK agent for AIS) commented: "With AIS, you don't get the same heat generation or magnetic variations that you would get if you used linear motors or electromagnetic actuators. This means you get excellent level accuracy in both the vertical and horizontal plane." Applications: The system can be used on any machinery that performs sensitive measurement or inspections, machine tools, lithography equipment, laser machines, high resolution electron microscopes and machinery for the semiconductor industry. DP