摘要:

In this article we present a three axis parallel drive microrobot. The robot consists of three linear actuators rigidly positioned in a plane with their translational axes arranged in parallel. Each actuator is connected to one apex of a low mass rigid tetrahedral frame by a four axis elastic hinge. Movement of each of the three linear actuators results in displacements of the corresponding hinged apices and, hence, the rigid tetrahedral frame. The fourth apex acts as the working tip which may be positioned anywhere within a workspace determined by the geometry of the robot and the displacement range of the actuators. When the actuator displacement is small compared to the dimensions of the frame the relationship between the displacement of the three actuators and the position of the working tip is well defined, being one to one and only mildly nonlinear (1&percent; nonlinearity for 1.5 mm actuator displacement on an 80 mm frame). A microrobot has been constructed with a workspace measuring 3 mm axially and 5.65 mm transverse to the robot axis. Below 100 Hz the working tip displacement is limited to 3 mm peak-to-peak in the axial direction and 5.65 mm peak-to-peak transverse to the axis. Above 100 Hz the working tip performance is acceleration limited with maximum displacement being inversely proportional to the square of the driving frequency, falling to 120 &mgr;m peak-to-peak in the axial direction at 500 Hz. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148342

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A continuous-purge pulsed valve has been designed to introduce supersonic jet samples into a vacuum chamber. The new valve design separates the heated sampling and transfer lines from the solenoid coils with a long metal valve stem, which is kept cool with annular cooling fins. The valve is heated using electrical heating elements wrapped around the valve stem. A precision-machined stainless steel plunger maintains a metal-to-metal seal at the valve orifice, which is broken when the induced magnetic field from the solenoid pulls the plunger upward. Stable gas pulse widths were obtained down to 200 &mgr;s, which compares favorably with the 165 &mgr;s value for the commercial unit which uses a small Teflon poppet instead of the metal plunger. ©1997 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148343

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A very simple but effective accessory, based on a couple of large area silicon photodiodes, is presented. It allows the analysis, by a conventional double-beam ultraviolet-visible spectro- photometer, of scattering samples. The accessory, very low in cost, can be installed and removed quickly and can be easily constructed by the users to match different commercial models. The layout and the wiring diagram of the unit are described and the performances are tested. ©1997 American Institute of Physics. 

ISSN:0034-6748    

DOI:10.1063/1.1148344

出版商:AIP    

年代:1997

数据来源: AIP