METROLOGICAL INSTRUMENT

摘要

A portable metrological instrument for measuring surface finish parameters has a main housing (1) which sits on a workbench (5). A slidable arm (3) can be extended or retracted over the bench (5) so as to move a stylus (21) over a workpiece (25). The stylus (21) is fitted to a gauge (19) mounted to the end of the arm (3). The mounting includes a vertically movable slider (15) which incorporates a mechanism for lifting the stylus (21) away from the workpiece (25) and lowering it back. The operation of the instrument is controlled by modular software which can be reprogrammed using an external device, and the machine is operated by a control panel (37) on the housing (1) or by an identical control panel (53) on a remote controller (55). The gauge includes an inductive sensor (75, 77), and the associated circuit includes automatically adjustable error cancelling devices (177, 179). The control system uses the sensed position of the arm (3) to estimate the speed of the motor (145) which drives the arm (3), avoiding the need for a shaft encoder on the motor (145).