Synchronization of External Axes, Torque Feed Forward Control

The axis values of the axes of an axis group are normally calculated at the end of the cycle after the application code programmed by the user has been run through. However, for certain applications it is necessary for these values to be available sooner in order to use them in the application code. The SMC_GroupUpdate function block makes sure that the values of all axes which are part of an axis group are updated immediately.

One use case for SMC_GroupUpdate is the synchronization of axes which are not part of the axis group. An example would be a second drive for the X-axis in the case of an XY gantry.

Before CODESYS SoftMotion version 4.13.0.0: An additional use case for the SMC_GroupUpdate function block is torque feed forward control. The axis values calculated in the current cycle can be used to calculate the suitable set torques using a dynamic model of the robot.

In CODESYS SoftMotion version 4.13.0.0 and higher: If a dynamic model has been assigned to the axis group using SMC_GroupSetDynamics, then the set torques are automatically calculated cyclically and can be used for torque feed forward control. The use of SMC_GroupUpdate is no longer necessary for this use case. For more information, see: Torque Limitation and Torque Feed Forward Control