Max Deviation and Max Angle in Robotmaster V7

Owned by Emile Bouthillier
Last updated: Jun 09, 2020
3 min read


The "Maximum Deviation" and "Maximum Angle" features are not straightforward.

These two features will allow you to increase or decrease the accuracy of your path by adding or removing points in non-linear regions of the path. In other words, if your path only contains straight lines, these parameters will not impact the number of path points.

When you click on the edge of a CAD model to create a path, the algorithm will verify the topology of the edge/face and if the edge/face is curved, the created path will either be a circular move or a series of small linear moves. In the second scenario (a series of small linear moves) we can control the number of lines created to approximate the curve by using the "Maximum Deviation" and "Maximum Angle" variables.



Impact of "Maximum Deviation" and "Maximum Angle"

To see the impact of these parameters, we need to focus on a small circular section of a path:

 

If we zoom in on the path shown above, we will see the impact of the "Maximum Deviation" and "Maximum Angle" variables:

 

The Maximum Deviation is the maximum distance between the original CAD model and any point on the linear segment created to approximate the curvature of the CAD.

The Maximum Angle is the maximum angle between the curved edge’s tangent line and the linear segment created to approximate the curvature of the CAD.

In most scenarios, one of the two parameters ("Maximum Deviation" or "Maximum Angle") will be more restrictive and it will be responsible for the creation of most of the path points along a curve.


Example

Scenario 1: The Maximum Angle is set to 1 degree and the Maximum Deviation is set to 0.1 mm.

Scenario 2: The Maximum Angle is set to 1 degree and the Maximum Deviation is set to 5 mm.

In these two cases, the exact same number of points and lines were created to approximate the curve because the value that was most restrictive was the Maximum Angle and it remained constant in both scenarios.

Summary

"Maximum Deviation" and "Maximum Angle" have a similar impact on the path. They either increase or decrease the accuracy of the path by increasing or decreasing the number of points and lines used to approximate curves. One of these parameters will usually be more constraining than the other and it will be responsible for the overall accuracy. If you want to change the accuracy of your path, you need to figure out which one currently has the biggest impact on your path or simply modify both.