Printed in the Federal Republic of Germany
TR-Electronic GmbH 2016, All Rights Reserved
09/29/2020
TR-EMO-BA-GB-0022 v03
Page 143 of 153
10.14 Gear backlash cancellation (Opmodes -48=0xD0)
Since the firmware version 6-May-2019 the new opmode -48= 0xD0 is available for
gear backlash cancellation. It works exactly equal to the opmode 1, except that the
target position is finally always approached in the same direction from a distance,
which is set by the parameter "Gear Backlash".
The absolute value of this parameter should be somewhat larger than the actual
backlash, so that the gear is pushed out of the backlash in any case.
If this parameter is positive, the target position is always approached from above,
otherwise always from below. If it is 0, this opmode works exactly the same as
opmode 1.
In order to maintain the accuracy of the position, this final move is always executed on
a drive command, even if the target position has not changed. In this case the drive
moves away by the "Gear Backlash" value, stops and returns.
If the drive is already approaching from the proper side, it nevertheless stops for a
short moment in a distance according to the "Gear Backlash" value. Thus the final
move is always performed with the same speed and acceleration.
The 2 points of the final move are indicated by the read-only parameters "Backlash
target pos." 1 and 2. 2 is always equal to the actual target position. 1 is the target
position plus the "Gear Backlash".
The "Backlash Trailing Pos." tries to estimate the output of a gearbox with a a positive
or negative backlash in the worst case.
First it calculates the distance from the trailing position to the actual one. If its sign and
the sign of the backlash are different, the trailing position is set equal to the actual
position.
Otherwise while the absolute value of the distance is less than the absolute value of
the backlash, it just keeps its value. Otherwise it is set equal to the actual position
minus the backlash.
By writing the "Gear Backlash" also the "Backlash Trailing Pos." is reset to the actual
position.
Required parameters:
"Gear Backlash/Pos.units" 0x2F0E:0x4 // must be somewhat larger than the actual
backlash.
"Backlash target pos.1/Pos. units" 0x2E05:0x11 // read-only.
"Backlash target pos.2/Pos. units" 0x2E05:0x12 // read-only.
"Backlash trailing pos./Pos. units" 0x2E05:0x13 // read-only.
