Control scheme and system for active vibration isolation

An apparatus for supporting a stage, said apparatus comprising:

• a base;
• a platform supported from said base;
• at least one stage configured to move about said platform;
• a plurality of pneumatic supports configured on said base to support said platform in a first direction;
• pressure control means for supplying and regulating each pressure of said plurality of pneumatic supports;
• a plurality of active supports configured on said base to support said platform in said first direction;
• and
• power control means for supplying and regulating the power to said active supports.

A control system for controlling an apparatus for supporting a stage, said apparatus comprising a base from which a plurality of pneumatic supports and active supports support a platform which in turn supports said stage and sensors for sensing pneumatic support pressure, platform position, and stage location, said control system comprising:

• a processor;
• and
• a computer program product containing:
• a model that produces a target pressure for each said pneumatic support;
• and
• instructions for:
• receiving data from pneumatic support pressure, platform position, and stage location sensors;
• producing target pressures for each pneumatic supports using said model and said stage location data;
• comparing said target pressures to said received pressure data;
• controlling valves to change said pressures so that said received pressures move toward said target pressures;
• comparing said received platform position data to a desired platform position;
• and
• controlling amplifiers to change power to said active supports so that said acquired platform position data moves toward said desired platform position.

A method for supporting and vibrationally isolating a platform, the platform itself supporting at least one stage, the method comprising:

• supporting a platform from a base using a plurality of pneumatic supports and a plurality of active supports, said platform itself supporting at least one stage and said platform having a desired position;
• modeling said pneumatic supports, said model providing target pressures for each said pneumatic support for an input stage location;
• moving said at least one stage about said platform during a process;
• adjusting said pneumatic supports to said target pressures;
• determining said platform position;
• regulating said active supports to move said platform toward said desired platform position.

A method for positioning and vibrationally isolating a platform and at least one stage in a process, said method comprising:

• designating a desired platform position;
• supporting said platform and stage primarily with a plurality of pneumatic supports from a base;
• further supporting said platform and stage with a plurality of active supports;
• moving said stage about said platform in a process;
• determining the location of said stage as said stage is moved about said platform;
• inputting said determined stage location into a model, said model providing a target pressure for each said pneumatic support based on said stage location;
• adjusting said pneumatic support pressures to said target pressures;
• comparing platform position after said adjusting step to said desired platform position;
• and
• controlling said active supports to move said platform closer to said desired platform position.

A stage device comprising:

• a platform;
• at least one stage supported by the platform, said at least one stage being movable relative to said platform;
• at least one pneumatic support that supports said platform in a predetermined direction;
• at least one active support connected to said platform, said at least one active support generating force that acts on the platform in said predetermined direction;
• and
• a control system connected to said at least one pneumatic support and said at least one active support, said control system including a first control loop and a second control loop, wherein said first control loop controls said active support based on information related to position of said platform and said second control loop controls said at least one pneumatic support based on a position of said at least one stage independently from said information of said position of said platform.