# Additive current dependent on velocity

## Additive current

The purpose of friction compensation is to compensate actually existing friction torque by way of an additional torque. It acts in the form of speed-dependent feedforward control of the motor current.

Principle of friction compensation

## Notice

It is basically sufficient to command a additive current to the drive on the setpoint side for friction compensation.

However, to determine the characteristic curve for the current and verify compensation, it is also necessary to read the actual current.

## Effect

The algorithm compensates for friction during path motions (v≠0) by an additional motor current.

## Control loop

The effect of friction compensation on closed-loop control is shown in the figure below.

Add friction compensation to the control loop of an axis

## Additional information

- Reverse the motion direction