I worked extensively with the people who developed the systems.
Yes, they have inertial guidance. You do not need mechanical gyros for inertial guidance. You use electronic ones. Tiny, minuscule, electronic ones.
You are mistaken about wikipedia here is a quote from them:
"It is a GPS- and inertial-guided munition capable of being used in close support situations within 75–150 meters (250–490 ft) of friendly troops or in situations where targets might be prohibitively close to civilians to attack with conventional unguided artillery fire."
Inertial guidance systems keep getting smaller and smaller.
A German test of the smart fuse which is added to conventional 155mm artillery shells found, at 27 km, 90% of the smart fuse shells hit within 5m of their target. That was in 2014.
Those fuses are very cheap compared to Excaliber rounds. The conventional shells do not have the extended range of Excaliber rounds.
They have gotten better. Most of the correction to the trajectory occurs before apogee of the flight of the projectile, so local defenses, such as jamming, are useless, and are mostly overcome by the inertial guidance, anyway.
The targeting is by Glonass.
GPS is at least as robust as Glonass.
I was part of the very large team which developed GPS. My contributions were data collection.
I studied Glonass, a bit. Not a bad system, but, unfortunately, with GPS already there, very little commercial market for Glonass. This limits the incentives for continual improvements.
As I have written, repeatedly: Smart munitions do not need laser guidance. It can be used with many. It can drop the error from 5 meters to .5 meters. But with an artillery shell, 5 meters is almost always enough.
Yes, they have inertial guidance. You do not need mechanical gyros for inertial guidance. You use electronic ones==
Electronic gyro? Let them use them. They are very inaccurate.
A German test of the smart fuse which is added to conventional 155mm artillery shells found, at 27 km, 90% of the smart fuse shells hit within 5m of their target. That was in 2014.==
It is GPS guided. It can be if GPS is not jammed. But all real material depos at this war always defended by AA machines and GPS jammers.
Most of the correction to the trajectory occurs before apogee of the flight of the projectile, ==
Why to correct at this stage? You kind of defeat a purpose. During flight there can be like atmospheric turbulence which drag away projectile and you are not correcting it anymore.
Russian shell is corrected just when it goes down on target so they are more precise then.
Not a bad system, but, unfortunately, with GPS already there, very little commercial market for Glonass. This limits the incentives for continual improvements.==
How GPS may get a commercial returns if it is just broadcasting system for anyone to listen? I doubt that GPS got any penny from Russia for example but we use it for years.
But Glonass is embedded to any weapon system Russia sells. SO any country say from Afrika may have a cheap high precision weaponry with satellite targeting. SO it is a commercial returns.
As I have written, repeatedly: Smart munitions do not need laser guidance. It can be used with many. It can drop the error from 5 meters to .5 meters. But with an artillery shell, 5 meters is almost always enough.===
If you need to hit up say one blindage or one tank or one ICV which you see from your drone then you will very need 0.5m precision. Russia uses them today exactly this way. To take out a blindage or a tank or a group of soldiers and so on. 5m is too much for such targets to destroy tank or blindage if it is just 10-20 pounds of explosive but just shake it and scratch it.