Research on High Power Direct Drive Differential Volume Control Electro-Hydraulic Servo System

For traditional direct drive volume control electro-hydraulic servo system, the servo motors rotary inertia is limited strictly, the speed of response is slow and the actuators reciprocating motion characteristics are not consistent. In order to solve these problems, this paper designs a kind of high power direct drive differential volume control electro-hydraulic servo system. It is instructive for design of hydraulic system which demands high output power, changes direction of motion frequently, needs high response frequency and requires the speed of reciprocating motion keep consistent.

The Double-Bridge Beam Structure with Slots for Microaccelerometer

Aiming at the increasingly demanding needs for high sensitivity and high response frequency, a novel accelerometer chip structure is proposed based on the improvement of stress distribution of the traditional double-bridge beam structure. Analysis and simulation proved that the double-bridge beam structure with slots, named as DBBS structure, got a better sensitivity and a satisfactory natural frequency compared with the double-bridge beam structure. The detailed fabrication processes were studied. Finally, faith of the prospective of the DBBS structure could be paid for the future applications in failure diagnosis, automobile detection, sports equipments and so on.

Fast Tool Servo Machining of Complex Surfaces and Microstructures

Optical components with complex surfaces or microstructures are more and more widely used, but it is very difficult to manufacture these components by using traditional mechanical fabrication methods. Fast Tool Servo (FTS) system driven by piezoelectric ceramic (PZT) can manufacture these complex surfaces or microstructures efficiently and accurately, owing to its high response frequency, good dynamic performances and high stiffness. In this paper, the cutting characteristics are studied in the FTS machining process, and the identifying algorithm of tool interference is given. A set of high-powered FTS system is developed, which consists of PZT, fast feeding device, DSP28335 control panel and ultraprecision machine tool. The testing results indicate that the FTS system’s motion resolution is 1nm, the stroke is 90μm, and the response frequency is 220Hz while moving distance is 36μm. On the basis of above work, three kinds of typical workpieces with complex surfaces are manufactured by using FTS system. The measuring results indicate that surface accuracy can reach PV 0.14μm, the roughness is less than Ra 12nm, and the means are presented to improve the machining accuracy.