A robust photoelectric angular position sensor especially for a steerable underground boring tool

In order to avoid the disadvantages of the present angular position sensors for determining the rotation orientation of a steerable underground boring tool, a new photoelectric method utilizing photoelectric switches and the corresponding sensor are established. The sensor comprises a gravitational ball, one or more light sources and an array of photodetectors, and realizes angular position measurement by setting a block between the light source and the corresponding photodetector which is rotated to the lowest point. The concrete configurations are described in detail and a typical prototype is illustrated. The photoelectric angular position sensor is compact, simple, low-cost. It can resist harsh environmental conditions such as vibration, excessive ambient temperature, dirt, moisture and dew, so it is especially well-suited for a steerable underground boring tool.