Basic Characteristics RAPID

TuneServo Tuning servos
Description
Tune_df
TuneServo is used to tune the dynamic behaviour of separate axes on the robot. It is not
necessary to use TuneServo under normal circumstances, but sometimes tuning can be
optimised depending on the robot configuration and the load characteristics. For external
axes TuneServo can be used for load adaptation.
Incorrect use of the TuneServo can cause oscillating movements or torques that
can damage the robot. You must bear this in mind and be careful when using the
TuneServo.
Note. To obtain optimal tuning it is essential that the correct load data is used.
Check on this before using TuneServo.
Tune_df is used for reducing overshoots or oscillations along the path.
There is always an optimum tuning value that can vary depending on position and
movement length. This optimum value can be found by changing the tuning in small
steps (1 - 2%) on the axes that are involved in this unwanted behaviour. Normally the
optimal tuning will be found in the range 70% - 130%. Too low or too high tuning values
have a negative effect and will impair movements considerably.
When the tuning value at the start point of a long movement differs considerably from
the tuning value at the end point, it can be advantageous in some cases to use an intermediate
point with a corner zone to define where the tuning value will change.
Some examples of the use of TuneServo to optimise tuning follow below:
IRB 6400, in a press service application (extended and flexible load), axes 4 - 6:
Reduce the tuning value for the current wrist axis until the movement is acceptable. A
change in the movement will not be noticeable until the optimum value is approached.
A low value will impair the movement considerably. Typical tuning value 25%.
IRB 6400, upper parts of working area. Axis 1 can often be optimised with a tuning
value of 85% - 95%.
IRB 6400, short movement (< 80 mm). Axis 1 can often be optimised with a tuning
value of 94% - 98%.
IRB 2400, with track motion. In some cases axes 2 - 3 can be optimised with a tuning
value of 110% - 130%. The movement along the track can require a different tuning
value compared with movement at right angles to the track.
Overshoots and oscillations can be reduced by decreasing the acceleration or the acceleration
ramp (AccSet), which will however increase the cycle time. This is an alterna-
RAPID Reference Manual 8-TuneServo-1