Monitoring an operating state of a valve

1. A device configured to monitor a state of a rotatable handle of a valve when the device is attached to the rotatable handle, the device comprising a vector magnetometer configured to measure a magnetic field;

the device further comprising a processing unit configured to:

obtain from the vector magnetometer measurements of the magnetic field when the handle is rotated;

calculate a change in the state of the rotatable handle based on a difference between the measurements of the magnetic field; and

report the change in the state.

2. The device according to claim 1 wherein the calculating of the change further comprises:

calculate an angle of rotation of the rotatable handle between the measurements.

3. The device according to claim 2 wherein the processing unit is further configured to calculate a total angle of rotation from the start to the end of the rotation as the change in the state.

4. The device according to claim 2 wherein the calculating further comprises, when obtaining a new measurement:

determine a new center of rotation of the rotatable handle between the new measurement and a previous measurement;

update a mean center of rotation based on the new center of rotation;

correct the calculated angle of rotation based on the updated mean center of rotation.

5. The device according to claim 4 wherein the calculating further comprises, when obtaining the new measurement:

update an accumulating angle of rotation with the corrected angle of rotation.

6. The device according to claim 5 wherein the total angle of rotation corresponds with the accumulating angle of rotation.

7. The device according to claim 1 further comprising a wireless interface; and

wherein the processing unit is further configured to report the change in the state by the wireless interface.

8. The device according to claim 1 wherein the device further comprises a battery; and

wherein the processing unit is further configured to set the device in a low-power sleep mode when the rotatable handle is not rotated; and

the device further comprising an accelerometer configured to instruct the processing unit to wake up the device when the handle is rotated.

9. The device according to claim 1 further comprising an inputting means configured to manually instruct the processing unit to initialize the state.

10. The device according to claim 1 wherein the processing unit is further configured to:

obtain from a fixed reference beacon measurements of a reference magnetic field; and

wherein the calculating of the change is further compensated by the reference magnetic field.

11. The device according to claim 1 wherein the processing unit is further configured to:

obtain measurements of the magnetic field from at least one other device of claim 1 ;

derive a reference magnetic field based on the obtained measurements of the device and the at least one other device; and

wherein the calculating of the change is further compensated by the reference magnetic field.

12. A valve comprising:

a rotatable hand; and

a device configured to monitor a state of the rotatable handle,

wherein the device includes a vector magnetometer configured to measure a magnetic field, and

wherein the device further includes a processing unit configured to

obtain from the vector magnetometer measurements of the magnetic field when the handle is rotated;

calculate a change in the state of the rotatable handle based on a difference between the measurements of the magnetic field; and

report the change in the state.

13. A method for monitoring a state of a rotatable handle of a valve, the method comprising the steps of:

obtaining from a device attached to the rotatable handle comprising a vector magnetometer measurements of a magnetic field when the handle is rotated;

calculating a change in the state of the rotatable handle based on a difference between the measurements of the magnetic field; and

reporting the change in the state.

14. A non-transitory computer readable storage medium having stored thereon executable instructions that when executed by one or more processors of a computer system configure the computer system to perform the method according to claim 13 .