IIO: angular measurement types.
Hi All
Just looking at add chan spec support for resolvers and realised that our representations of angular measurements have become somewhat confused.
Right now we have
IIO_GYRO -> angular velocity (units radians / sec)IIO_ROT -> vertical rotation position (undocumented)IIO_ANGL -> rotation angle (currently integrated version of IIO_GYRO, undocumented)
For resolvers we seem to need
Absolute rotation position (IIO_ANGL?) set units to radians Angular velocity (IIO_GYRO? - odd naming here) randians / sec
So, proposal is to rename IIO_GYRO - > IIO_ANGL_VEL
Anyone have an thoughts on this?
Jonathan
Am Donnerstag, 29. September 2011, 15:13:44 schrieb Jonathan Cameron:
Quoted 13 lines
Hi All
Just looking at add chan spec support for resolvers and realised that our representations of angular measurements have become somewhat confused.
Right now we have
IIO_GYRO-> angular velocity (units radians / sec)IIO_ROT-> vertical rotation position (undocumented)IIO_ANGL-> rotation angle (currently integrated version ofIIO_GYRO, undocumented)
Quoted 8 lines
For resolvers we seem to need
Absolute rotation position (
IIO_ANGL?) set units to radians Angular velocity (IIO_GYRO? - odd naming here) randians / secSo, proposal is to rename
IIO_GYRO- >IIO_ANGL_VELAnyone have an thoughts on this?
The question is whether we want to have names according to the physical propery we measure or names according to the common terminology of the devices that measure that property.
i.e. gyros measure angular velocities. Are there other devices that measure angular velocities? I think not.
Devices that measure horizontal rotation are usually called inclinometers. Devices that measure vertical rotation are for example compasses, but there could be others.
Devices that measure rotation angles are usually called resolvers, but this might also be non exclusive.
Do we want to distinguish between these? They all return angles.
And what about sensors that measure rotations? They can deliver angles outside [-PI:+PI] (i.e. several rotations), but that makes no sense for compasses.
Nevertheless I think we can keep IIO_GYRO for devices that measure angular velocities, as this is a very common name for these.
Regards,
Manuel
Quoted 19 lines · Manuel Stahl
Am Donnerstag, 29. September 2011, 15:13:44 schrieb Jonathan Cameron:
Quoted 18 lines
Hi All
Just looking at add chan spec support for resolvers and realised that our representations of angular measurements have become somewhat confused.
Right now we have
IIO_GYRO-> angular velocity (units radians / sec)IIO_ROT-> vertical rotation position (undocumented)IIO_ANGL-> rotation angle (currently integrated version ofIIO_GYRO, undocumented)For resolvers we seem to need
Absolute rotation position (
IIO_ANGL?) set units to radians Angular velocity (IIO_GYRO? - odd naming here) randians / sec
Quoted 7 lines
Quoted 3 lines
So, proposal is to rename
IIO_GYRO- >IIO_ANGL_VELAnyone have an thoughts on this?
The question is whether we want to have names according to the physical propery we measure or names according to the common terminology of the devices that measure that property.
What they measure. It is true for every other type (IIRC)
Quoted 3 lines
i.e. gyros measure angular velocities. Are there other devices that measure angular velocities? I think not.
resolvers. There is a reason I was looking at this ;) Can technically be done with accelerometers in a number of locations or an accelerometer / magnetometer pair.
Also, the term gyroscope may mean a device for measuring absolute rotation or rotational velocity. I've heard some argue that the term is completely missused for mems devices...
Quoted 2 lines
Devices that measure horizontal rotation are usually called inclinometers.
But they measure inclination so that one is fine.
Quoted 5 lines
Devices that measure vertical rotation are for example compasses, but there could be others.
Devices that measure rotation angles are usually called resolvers, but this might also be non exclusive.
Also measure angular velocity (or at least the ad2s1200 does).
Quoted 2 lines
Do we want to distinguish between these? They all return angles.
Nope. That's my argument.
Quoted 3 lines
And what about sensors that measure rotations? They can deliver angles outside [-PI:+PI] (i.e. several rotations), but that makes no sense for compasses.
It does if you have sufficient tracking to know it happened. Still I agree it doesn't make sense when using them for navigation. We probably don't need to worry about it though. Any userspace app should trivially be able to correct wrap around if it expects the device to be used as a compass.
Quoted 3 lines
Nevertheless I think we can keep
IIO_GYROfor devices that measure angular velocities, as this is a very common name for these.
I'd agree except that it makes things inconsistent. We already have one definitely non gyroscope user. Right now the change is trivial. We can't really do it later.
Jonathan