Difference between revisions of "Tracking error"
From Granite Devices Knowledge Wiki
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*Bad servo tuning → Adjust feedback gains, see [[Servo motor tuning guide]] | *Bad servo tuning → Adjust feedback gains, see [[Servo motor tuning guide]] | ||
*Asking too much out of motor so motor can't keep up with motion: | *Asking too much out of motor so motor can't keep up with motion: | ||
| − | **Too fast acceleration → reduce acceleration rate [[CAL]] OR increase motor current limits, especially [[ | + | **Too fast acceleration → reduce acceleration rate [[CAL]] OR increase motor current limits, especially [[MMC]] |
**Too fast velocity → reduce velocity limit [[CVL]]. If motor can't reach it's full speed, reason may be too low drive supply voltage or partial loss of encoder signal (encoder not being able to operate at such speeds or interference/bad wiring is causing the error) | **Too fast velocity → reduce velocity limit [[CVL]]. If motor can't reach it's full speed, reason may be too low drive supply voltage or partial loss of encoder signal (encoder not being able to operate at such speeds or interference/bad wiring is causing the error) | ||
Revision as of 19:38, 22 October 2013
Tracking error means the difference between the setpoint and measured actual output value. For example in a linear axis tracking error can be the distance between setpoint position and the position where axis really lies at the given moment.
Tracking error fault
In modern motor drives it's possible to define the permissible maximum value of tracking error which is allowed before drive enters in a fault state and stops. Tracking fault is useful for protecting the machine or users from damage if something is preventing mechanism from moving. In Granity this value is entered in FPT and FVT parameters.
Fault countermeasures
Tracking error fault is probably the most common fault in servo motor systems. Typical reasons and counter measures are:
- Too low fault tolerance levels → Increase FPT, FVT and/or FFT parameters
- Bad servo tuning → Adjust feedback gains, see Servo motor tuning guide
- Asking too much out of motor so motor can't keep up with motion:
- Too fast acceleration → reduce acceleration rate CAL OR increase motor current limits, especially MMC
- Too fast velocity → reduce velocity limit CVL. If motor can't reach it's full speed, reason may be too low drive supply voltage or partial loss of encoder signal (encoder not being able to operate at such speeds or interference/bad wiring is causing the error)
