The invention discloses a six-degree-of-freedom active vibration isolation device, which has the six-degree-of-freedom vibration isolation and positioning functions. The device comprises a lower platform, an upper platform and six support legs, wherein the six support legs are respectively connected with the upper platform and the lower platform through fixing blocks to form a Stewart parallel mechanism, the positions of the three fixing blocks on the lower platform are arranged in an equilateral triangle shape, the positions of the three fixing blocks on the upper platform are also arranged in an equilateral triangle shape, the six support legs are same in the structure, two adjacent support legs are mutually vertical with each other, each support leg comprises an active executer and an air spring which are formed into a parallel structure, and each air spring is used as a passive vibration isolation part. The device has the advantages that the combined method of active vibration isolation and passive vibration isolation is adopted, the ultra-low inherent frequency is realized, and the vibration with frequency exceeding the inherent frequency is effectively isolated; the good attenuation on the six-degree-of-freedom vibration is realized, and the precise positioning of six degrees of freedom is realized.

Six-degree-of-freedom active vibration isolation device

The present invention discloses a Stewart active platform and a vibration abatement method. The Stewart active platform includes a load platform, a basic platform, a controller, an acceleration sensor and piezoelectric single-legged structures. Each piezoelectric single-legged structure includes an upper flexible hinge, a force sensor, a piezoelectric actuator, and a lower flexible hinge. The force sensor, the piezoelectric actuator and the acceleration sensor are connected to the controller. The method includes the steps as follows: 1) the controller acquires a feedback control signal; 2) the controller acquires a feedforward control signal; 3) the controller acquires a composite control voltage of a feedback voltage and a feedforward voltage; 4) and the composite control voltage is outputted to the piezoelectric actuator, and the piezoelectric actuator applies an acting force to the load platform. A control algorithm adopted by the invention, which utilizes a PI force feedback algorithm, not only can effectively reduce a natural system frequency and a vibration resonance peak, but also efficiently iterate by the utilization of an RLS adaptive algorithm with an efficient evaluation performance so as to find an optional weight value, and thereby reducing the vibration of the load platform.

Stewart active platform and a vibration abatement method based on the Stewart active platform

The invention provides a zero stiffness vibration isolator and a vibration isolation system for air floating ball bearing angle decoupling and belongs to the technical field of precision vibration isolation. A sleeve of a vibration isolator main body and a lower installation plate and a piston cylinder and the sleeve are lubricated and supported respectively through air floating surfaces, angular motion freedom degree between an upper installation plate and the lower installation plate is decoupled through an air floating ball bearing, a position closed-loop feedback control system is formed by a voice coil motor, a displacement sensor, a limit switch, a controller and an actuator to perform accurate control on the relative position of the upper installation plate and the lower installation plate. The zero stiffness vibration isolator and the vibration isolation system for the air floating ball bearing angle decoupling have the advantages of being free of three-dimensional stiffness, high in positioning accuracy and angle decoupling and capable of obtaining very low inherent frequency and prominent low frequency/ultra-low frequency vibration isolation performance, thereby effectively solving problem of high-performance vibration isolation in ultra-precise measurement devices and processing devices, in particular to step scanning photoetching machines.

Zero stiffness vibration isolator and vibration isolation system for air floating ball bearing angle decoupling

A self-adaptation vibration absorber comprises two major parts including a vibration absorption system and a master control system which are integrated in a shell. The shell comprises an upper shell body, a middle shell body and a lower shell body from top to bottom. The vibration absorption system at least comprises a mass block, a spiral spring, an air spring, a separation piston, a screw, a lower servo motor, a selection gear, a main gear and an upper servo motor, wherein the mass block and the spiral spring are arranged between the upper shell body and a cover plate, and the air spring, the separation piston, the screw, the lower servo motor, the selection gear, the main gear and the upper servo motor are arranged between the cover plate and the middle shell body. The separation piston capable of moving up and down is arranged in an air chamber of the air spring and divides the air chamber of the air spring into an upper air chamber body and a lower air chamber body, and the volume ratio of the upper air chamber body to the lower air chamber body is changed through the up-down movement of the separation piston. The master control system comprises a wall penetrating socket, a power source, a master control board card and a sensor. The self-adaptation vibration absorber is simple in structure, convenient to use, low in cost and good in vibration restraining capability. Power consumption is greatly reduced compared with power consumption of an active vibration restraining method, the vibration reducing efficiency is high, the self-adaptation vibration absorber can adapt to various work conditions, and the application range is wide.

Self-adaptation vibration absorber

The invention provides a vibration isolator with characteristics of two-dimensional flexible hinge angle decoupling and magnetic levitation plane drive positioning and belongs to the technical field of precise vibration isolating technologies. A sleeve of a vibration isolator main body and a lower installing plate are born though magnetic levitation action of a magnetic levitation plane motor, a piston barrel and the sleeve are respectively lubricated and supported through air floating faces, and angle motion freedom between an upper installing plate and the lower installing plate is decoupled through a two-dimensional flexible hinge. A motor, a displacement sensor, a limiting switch, a controller and a driver form a position closed loop feedback control system for accurately controlling opposite positions of the upper installing plate and the lower installing plate. The vibration isolator has the three-dimensional approximate zero stiffness, high positional accuracy and angle decoupling characteristics, can have ultra-low inherent frequency and prominent low-frequency/ultra-low-frequency vibration isolating performance, and accordingly and effectively solves the high-performance vibration isolating problem of a precise measuring instrument, a processing device and especially a step scan photo-etching machine.

Vibration isolator with characteristics of two-dimensional flexible hinge angle decoupling and magnetic levitation plane drive positioning

The invention discloses a self-adaptive damping variable ultra-precise vibration absorber, which has the following structure: the exterior of a metal shell is in an upper end-opened cylinder shape; the metal shell is hollow, is divided into an upper hollow part and a lower hollow part by a clapboard, has an H-shaped section; a lower cavity is formed in the hollow part on the lower part; an upper cavity is formed by connecting the upper hollow part and a piston mechanism through a film structure in a sealed mode; an air inlet is formed at the bottom of the lower cavity; a communicating pipeline with a throttling valve is arranged between the lower cavity and the upper cavity; a load connecting plate is fixedly connected with the upper end face of the piston mechanism; an absolute velocity sensor is arranged on the load connecting plate; a non-contact eddy current proximity sensor is arranged on the upper end part of the metal shell; an active actuator is arranged between the metal shell and the load connecting plate; and the load connecting plate is used to be fixedly connected with load. The self-adaptive damping variable ultra-precise vibration absorber can well attenuate vertical vibration and perform on-line self-adaptation without off-line debugging, and can provide hyperstatic environment for a photoetching machine and other precision equipment.

Xuedong Chen

Papers

Self-adaptive damping variable ultra-precise vibration absorber