13. Path Finding - Type Dependent Options
Tutorial
This tutorial will look at the options made available when specific path finding types are selected. This tutorial specifically focuses on touch sense and Laser 1D unique options.
Prerequisites and Resources
Before starting with the tutorial, ensure to have the KUKA KR8 example cell downloaded and imported into Verbotics Weld. This cell is available to download here.
This walkthrough also uses the path finding types example project which can be downloaded here.
Video Tutorial
Step by Step Guide
Step 1: Touch Sense and Laser 1D Shared Options
Start by opening weld settings and locating the two path path finding settings labelled after the touch sense and laser 1D path finding types.
Below the general options covered in the previous path finding overview tutorial, you should see a group of settings labelled after the currently selected path finding type. Looking closely at the 2 path finding settings, notice that all the options found in touch sense, can also be found in the laser 1D options, with only minor adjustments to their phrasing.
Additional Options
While laser 1D does contain options not found in touch sense, the start of this tutorial will focus on the common options.
Options for Restricting Direction of Sensing Motions
The first options to look at are Limit Sensing in 2 Directions, and Require Sensing in all 3 Directions at.... Both of these options impact the amount of sensing operations permitted when planning the path finding for each weld.
Go ahead and navigate to the “Limit 2 Directions” and “Require 3 Directions” path finding setting, and you’ll notice these have each had one of these 2 options enabled.
To explore these 2 settings further by looking at their effects, go and return to the main viewer. Then select welds 1 and 2.
Welds 1 and 2 have had the path finding settings “Limit 2 Directions” and “Require 3 Directions” applied respectively. You should notice that both welds share similar path finding operations with 2 perpendicular senses occuring at the start and end of the weld.
However, if you take a closer look at weld 2, its 2 sensing groups also have an additional sensing motion on the outer plate in a 3rd direction. This additional motion has been created in response to enabling the require sensing in 3 directions option.
While this 3rd motion has been created at both the start and end of the weld, this option also allows you to specify the locations to conduct this 3rd weld.
2 Senses |
3 Senses |
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Return back to weld settings, and open the “Require 3 Directions” settings, open the drop-down box in our enabled option for sensing directions. You’ll see in addition to the previously selected “Start and end”, instead this 3rd sense can be required to be conducted at either the start or the end, or only at one of the 2 ends.
Require 3 Directions Locations
Note
This option is useful for ensuring higher quality path finding results, however its use can be restricted by a parts geometry causing a 3rd sense to be impractical/impossible.
Options for Avoiding Features
Now return back to weld settings and navigate to the Avoid Features Path Finding setting. In this setting, you’ll find 2 enabled options, these being avoid sensing near welds and avoid sensing on curved surfaces.
Avoid Options
When conducting path finding, the accuracy of the path finding results can often be reduced by certain features on the parts being sensed. 2 of these features are curved surfaces and welds. To ensure better path finding results, you can enable the avoid sensing near welds and avoid sensing on curved surfaces options.
Return back to the main window and select welds 3 and 4 to see how these options can affect the planned path finding.
First, look at the motions created for weld 3 which has had the Avoid Features setting applied. Notice, the 2 parallel motions at the centre of the weld are distanced from both where the weld will occur and the curved section of the plate. Additionally the 3rd sense is conducted much further away on the plate opposite the section being welded.
However, now shift your focus to weld 4, which is permitted to perform sensing regardless of the feature. Notice that not only is a weld planned along the curved section of the plate, there’s also a sense conducted right along where the weld is planned.
Avoid All |
Sense All |
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It’s much better to avoid these features to ensure consistent offsets from the path finding results. This is especially true with curves, as unlike when sensing a flat plane, any slight positional inaccuracy when sensing on a curve can greatly effect the sensor readings.
Options for Altering Surface Angle
Moving onto the next option, go ahead and return back to weld settings. The next setting you’ll be looking at is the Max Surface Angle 0.
While looking at the options for this setting, navigate to the bottom of the additional options where you’ll find the Maximum Surface Angle from Search Direction option.
This option allows you to limit much the angle of the torch can differ from the angle of a weld during a search motion. Below are 2 diagrams explaining this option, click the diagrams to zoom and learn about how the option works.
Touch Sense Diagram |
Laser 1D Diagram |
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The value you set for the maximum surface angle from search direction will affect how far from the search angle the sensing motion can differ. In this graphic, you can see when set to 0, the sensing motion follows a path aligned to the search angle. However, when set to 30, the sensing motion can be generated up to 30 degrees away from the search angle, which is useful for sensing on inclined part surfaces.
When using touch sense, the sensing motion path is the path the torch travels along when sensing, however if you instead were using laser 1D, the sensing motion would follow the path the laser travels along when sensing.
Returning back to the example project, in weld settings notice 3 path-finding settings referring to the maximum allowable surface angle, each of these has had their maximum surface angle from search direction set to 0, 30 and 60 respectively.
Now navigate back to the main viewer, where you’ll find welds 5,6 and 7, which have had the settings with a maximum search angle of 0, 30 and 60 applied respectively.
Start with weld 5, which has the max surface angle 0 setting applied. Notice it has no issue planning path finding operations on the panel being welded.
However, if we look at welds 6 and 7 a, which also have this setting, you’ll see the maximum surface angle of 0 restricts them from conducting this search on their own plates.
0° |
30° |
60° |
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In order to allow these 2 welds to have path finding motions planned on their own plates, you need to apply settings with an increased max search angle.
As such, shift your focus to 6b and 7b. These 2 welds have both had the max surface angle 30 and 60 settings applied respectively. Now you’ll find sensing motions planned on both of the slanted panels, with increase max surface angle of 60 allowing for the increased slant of weld 7’s panel.
Step 2: Options Unique to Laser 1D
For the options unique to Laser 1D sensing only, return back to weld settings and take a look at the default laser 1D setting. In the 1D laser options at the bottom of the list, notice the additional “Avoid” setting and the “additional incidence angle” setting.
Start with the first of those, which is “Avoid reflections causing invalid sensor readings”. 1D laser sensors can sometimes be susceptible to invalid sensor readings when reflection occurs. While enabling this option won’t effect the positioning of sensing operations, it instead will ignore certain values in areas where reflection was likely to occur.
While enabling this option doesn’t visually seem to make a difference in the simulation, it can be useful to enable if you know this may be an issue for your project.
The final option left to look at is the “Limit Incidence Angle Option”. For this, go ahead and select the “limit incidence angle 45” path finding setting. For a better understanding of how this option works, see our graphic below:
Limit Incidence Angle Diagram
Unlike the maximum surface angle, which focused on the angle of the path the torch travelled along compared to the search direction. The incidence angle instead refers to the angle between the laser and the surface being sensed.
Go ahead and return to the main window and select welds 8 and 9, which have both had the limit incidence 45 and 60 settings applied respectively.
With weld 8 selected, if you watch the simulated path finding, you should see the 45 degree angle the laser approaches the surface at. Or if you switch to weld 9, you should see it approaches the base plate at the limited 60 degree. Limiting the incidence angle helps reduce reflections, and thereby reduces the chance of invalid or poor sensor readings.
45° |
60° |
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. With that, we’ve covered all the additional options unique to the touch sense and laser 1D path finding. If you’d like more detail on each of these options, make sure to visit the weld settings and the path finding reference pages.