Developments in inductive analogue transducers for 360° rotation or tilt, and for linear displacement

Electrical data corresponding to degrees of angular rotation or displacement, together with associated or derived information regarding speed, direction and total turns traversed, are required increasingly for measurement and control purposes in many fields of application to machinery and robotics above and below ground. Such data may also be needed in nominally static applications in order to establish or measure a degree of tilt, or warn operators of moving machinery against hazards arising from excessive tilt. While there are many ways of deriving the information electrically, from simple potentiometers when sliding contacts are acceptable through to precision capacitance-based bi-axial tilt sensors, most analogue devices are limited in the angular range which can be encompassed by a single channel of measurement. All, however, give absolute information, i.e. the data is available at switch-on and under standstill as well as under dynamic conditions. During the study and development of attitude sensing equipment for the location and control of underground boring tools, a technique has been devised which, it is believed, offers a new approach to the problem of designing the most cost-effective methods of deriving angular data. The same principle can be extended to cover linear motion and displacement sensing