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M4220170607EN
UI Robot Technology Co. Ltd.
UIM2842
rotation direction is change, in certain angle, though the screw is turing, the nut will not
drive the table moving until the gap is eliminate, this gap is known as backlash, which is
reflected in the rotation angle of screw. Quantitatively, if the screw rotates clockwise to
drive the nut moving 5mm forward, then, rotates anticlockwise for the same cycles, the nut
will moving backword 4.99mm, the difference between the two value is the backlash.
Because of backlash, once reverse motion starts, the accumulative error will increase until
the backlash is compensate, then the accumulative error tends to be steady. The influence
caused by backlash is considerable in a reciprocating motion.
UIM2842 controllers provide the function of backlash compensation to reduce the influence
on mechanical transmission accuracy.
To compensate backlash, user needs to set a reference backlash first, then once there is
a backlash, user can compensate it by sending instruction BLC. Since this instruction
compensate backlash automatically when motion direction changes, and the direction
before can not get automatically, then it will be thought as no backlash exsiting at the initial
moment. Therefore, user must ensure that there is no backlash before sending instruction
BLC.
The units of backlash compensation value is pulse, the range is 0 ~ 65536 (recommended
value <5000), the default value is 0.
7.8 Advanced Motion Control Instructions
There are 6 additional instructions added as listed below.
1) Enable / disable MCFG: MCF; User can clear the CM bit of Master Configuration
Register (MCFG<CM>=0) to disable the module or set the CM bit (MCFG<CM>=1) to
enable the module.
2) Set acceleration: MAC; There are two ways to set the acceleration rate:(Figure7-12):
Value mode
If the AM bit of the Master Configuration Register is clear to zero
(MCFG<AM>=0), then the value of the instruction will be interpreted as the value of the
acceleration rate. The range of the input value is 1 ~ 65,000,000 and unit is
pulse/sec/sec or pulse / square-second.
Period mode
If the AM bit of Master Configuration Register is set to one
(MCFG<AM>=1), then the value of the instruction will be interpreted as the period of
the acceleration, or in other words, the time used for motor to accelerate to the desired
speed from current speed. The range of the input value is 1 ~ 60,000 milliseconds, i.e.,
0.001~ 60 seconds.
3) Set deceleration: MDE; Similar to mACC, the deceleration also has two ways to set as
listed below.
Value mode
If the DM bit of the Master Configuration Register is clear to zero
(MCFG<DM>=0), then the value of the instruction will be interpreted as the value of the
deceleration rate. The range of the input value is 1 ~ 65,000,000 and unit is
pulse/sec/sec or pulse / square-second.
Period mode
If the DM bit of Master Configuration Register is set to one
(MCFG<DM>=1), then the value of the instruction will be interpreted as the period of
the acceleration, or in other words, the time used for motor to decelerate to the desired
speed from current speed. The range of the input value is 1 ~ 60,000 milliseconds, i.e.,
0.001~ 60 seconds.
4) Set maximum starting speed: MMS
5) Set maximum cessation speed MMD
6) Set backlash compensation value: BLC