Backlash Compensation - Galil Motion Control DMC-1600 Series User Manual

Table of Contents

For example, to configure the main encoder for reversed quadrature, m=2, and a second encoder

of pulse and direction, n=4, the total is 6, and the command for the X axis is

Additional Commands for the Auxiliary Encoder

The command, DE x,y,z,w, can be used to define the position of the auxiliary encoders. For

example,

sets their initial values.

The positions of the auxiliary encoders may be interrogated with the command, DE?. For example

returns the value of the X and Z auxiliary encoders.

The auxiliary encoder position may be assigned to variables with the instructions

The command, TD XYZW, returns the current position of the auxiliary encoder.

The command, DV XYZW, configures the auxiliary encoder to be used for backlash

compensation.

Backlash Compensation

There are two methods for backlash compensation using the auxiliary encoders:

To illustrate the problem, consider a situation in which the coupling between the motor and the

load has a backlash. To compensate for the backlash, position encoders are mounted on both the

motor and the load.

The continuous dual loop combines the two feedback signals to achieve stability. This method

requires careful system tuning, and depends on the magnitude of the backlash. However, once

successful, this method compensates for the backlash continuously.

The second method, the sampled dual loop, reads the load encoder only at the end point and

performs a correction. This method is independent of the size of the backlash. However, it is

effective only in point-to-point motion systems which require position accuracy only at the

endpoint.

Continuous Dual Loop - Example

Connect the load encoder to the main encoder port and connect the motor encoder to the dual

encoder port. The dual loop method splits the filter function between the two encoders. It applies

108 • Chapter 6 Programming Motion

Reverse pulse & direction

CE 6

DE 0,500,-30,300

DE ?,,?

V1= _DEX

1. 7Continuous dual loop

2. Sampled dual loop

Reversed pulse & direction

DMC-1600

Table of Contents