Parametering

Activation

The temperature compensation can be switched on in the axis parameter list [AXIS] of the related axis by P-AXIS-00271:

kopf.achs_nr        1
#
# temperature compensation on/off
lr_param.temp_comp  1

Beside this for TwinCAT the compensation also can be selected via ADS-write access in the GEO task (Port 551).

TEMPC::is_active IGrp = 0x20300, IOffs = 0x10041

Effectiveness

The temperature compensation is enabled, if:

Reference measuring

To be able to define the parameters of the temperature compensation at first a reference measuring with an external position measuring system must be done. During this process for varying temperatures the deviations of the axis positions between internal and external measuring system are determined.

Parametering 1:
Figure 1-9: Reference measuring at varying temperatures

Determination of parameters

The parameters reference position, shift and coefficient can be taken from the measuring curve. Out of this later the values at a given temperature can be determined. From the measured temperature curves non-measured temperatures can be defined via inter- or extrapolation.

If the selected reference position is the virtual intersection point of the approximated linear curve, the shift depends on the temperature. In this case, for the varying temperatures only the coefficient must be adjusted new.

Influence of temperature

The individual parameters can be adjusted by the PLC depending on the current temperature. For this a specific temperature signal (sensor) is transmitted to the PLC.

From this signal the PLC derives the parameters.

Changing of parameters

Via download of the axis parameter list the individual parameters can be changed.

kopf.achs_nr                    1
#
# temperature compensation on/off
lr_param.temp_comp              1
# reference position
lr_param.temp_comp_position_0   100 [0.1µm]
# reference offset
lr_param.temp_comp_offset_0     40 [0.1µm]
lr_param.temp_comp_coefficient  4000 [µm/m]
#

Beside the download there also exists a read/ write manipulation for parameters via direct ADS access in the GEO task (Port 551). For example, the first axis can be addressed via following index group and index offset:

TEMPC::is_active IGrp = 0x20300, IOffs = 0x10041
TEMPC::coefficient IGrp = 0x20300, IOffs = 0x10043
TEMPC::offset_0 IGrp = 0x20300, IOffs = 0x10044
TEMPC::position_0 IGrp = 0x20300, IOffs = 0x10045
Parametering 2:
Figure 1-10: ADS access via browser on parameters of temperature compensation

Monitoring distribution of compensation values

For every interpolation cycle the compensation values are re-calculated. If the change per cycle exceeds the given maximum axis acceleration, this change can be output via a filter in several cycles.

For this in the axis parameter list the number of cycles of the sin²- filter can be set. Per default the value is one cycle.

kopf.achs_nr                 1
#
#Number of cycles of the sin²-filter
lr_param.temp_comp_n_cycles  20
Parametering 3:
Figure 1-11: Distribution of the compensation values over 20 cycles with a sin²- filter during a short deselection of the temperature compensation

Display of compensation

Beside the download there also exists a read/ write manipulation for parameters via direct ADS access in the GEO task (Port 551). For example, the first axis can be addressed via following index group and index offset:

TEMPC::is_active IGrp = 0x20300, IOffs = 0x10041
TEMPC::actual_offset IGrp = 0x20300, Ioffs = 0x10042

Display of axis position

During active temperature compensation the normal command positions and current positions of the axis are displayed without any manipulation.

The compensations are considered first before the output on the drive bus. So they can be checked in the position values of the drive bus (dig_cmd_pos, dig_act_pos).