Introduction

MotoSim allows users to define external axes when creating a Station within a simulation controller. These external axes are commonly used to represent auxiliary motion devices, such as linear tracks, sliders, or positioners. That extends the working envelope of a robotic system. Proper configuration of axis type is essential to ensure that simulated motion accurately reflects the intended physical behavior of the device.

Problem

When an external axis is created as a Station, the controller defaults the axis type to rotational motion, regardless of the units specified during setup. This occurs even when the axis is configured to move in millimeters rather than degrees. As a result, the simulated axis behaves incorrectly, rotating instead of translating, which misrepresents the true kinematics of the device and undermines the accuracy of the simulation.

Solution

To correct this and enforce linear motion, the following procedure should be followed:

1. Initialize the Controller and proceed through the standard controller initialization process, filling out all required specifications for the external axis as normal.
2. Complete Setup and Reboot Once initialization is complete…save and then close the simulation.
3. Edit the .VCL File located in the sim folder.
4. Look for the first mention of the controller and specifically the Station (S01).
5. Set the Axis Type to a linear direction (X, Y, or Z)…this defines the new motion as linear:
6. AXIS1=(TYPE=Z).
7. Note: If the simulation includes multiple controllers, this edit must be applied to the .vcl file for each relevant controller.
8. Save and close the .vcl and reload the simulation. The Station will now operate with linear motion along the specified axis.

References

For additional information, see section 13.6.2 of the MotoSimEG VRC Manual, which provides further detail on external axis configuration.