Sensors

1. An artificial whisker sensor comprising an elongate body having a root end and a tip end, in which the elongate body tapers from the root end to the tip end so that the root end is wider and the tip end is narrower, the root end is mounted in a hub, in which the hub is mounted in an elastomeric block so as to be in a suspended, free pivoting joint with a restoring force for the hub provided by the elastomeric block and being such that the pivot point of the whisker is at substantially the centre of the hub, a magnet is attached to the hub, the magnet is located axially above a magnetic field sensor for detecting the orientation of the magnet, in which deflection of the elongate body rotates the magnet about the pivot point such that it conveys the 2D angular pivot position of the elongate body.

2. The sensor according to claim 1 , in which the hub is mounted in a polyurethane-filled follicle case.

3. The sensor according to claim 1 , comprising a follicle case and a cast-in-place elastomeric block in the follicle case.

4. The sensor according to claim 3 , in which the follicle case comprises an opening for the elongate body and an opening for the magnet.

5. The sensor according to claim 1 , in which the magnetic field sensor is a tri-axis Hall effect sensor.

6. The sensor according to claim 1 , in which the magnet is bonded to the hub.

7. The sensor according to claim 1 , in which the tapering of the elongate body from the root end to the tip end is generally constant along the length of the elongate body.

8. The sensor according to claim 1 , in which the hub comprises a flange.

9. The sensor according to claim 8 , in which the elongate body is formed from a composite material.

10. The sensor according to claim 9 , in which the elongate body is formed from GRP.

11. The sensor according to claim 1 , in which the elongate body has a generally elongated cone shape.

12. The sensor according to claim 1 , in which the elongate body is approximately 1.5 mm at the root end and approximately 0.7 mm at the tip end.

13. The sensor according to claim 1 , in which an accelerometer is provided at or near the root end of the elongate body.

14. A vehicle provided with one or more artificial whisker sensors according to claim 1 .

15. A method of exploration using one or more artificial whisker sensors according to claim 1 .

16. The method according to claim 15 , comprising the step of measuring and/or calculating and/or inferring whisker speed and/or material viscosity.

17. The method according to claim 15 comprising the step of moving the elongate body through material of interest and in doing so causing vortex-induced vibration; and measuring the frequency spectrum of the vibration.