| 摘要 |
A down hole surveying tool (10) is for directional surveying of boreholes. The tool (10) includes a body (11) which accommodates a composite sensor device (17). The sensor device (17) is supported for rotation about an indexing axis (4) in a rotary mount (31) which provides an indexing platform (33). The sensor device (17) can be indexed about the indexing axis between two indexing positions which are 180 degrees apart. An indexing mechanism (70) is provided for selectively indexing the sensor device (17) about the indexing axis (4). The sensor device (17) includes a two-axis gyroscope (13) and a two-axis accelerometer (15) connected together and rotatable in unison. The indexing axis (4) is perpendicular to the two sensitive axes of the gyroscope (13) and the two sensitive axes of the accelerometer (15). The gyroscope (13) and accelerometer (15) are rigidly fixed with respect to each other to provide a sensor package which constitutes the composite sensor device (17). |
