The part height you must enter in this step is the height where the pick point is placed.
EYE+ corrects the parallax effect induced by the variation of the
position of the parts on the Asycube surface by adding an offset to the X and Y coordinates according
to its position on the platform. A part located on the edge of the platform will have a greater offset than a part
located in the middle. To calculate these offsets, the system must identify the height of the part where you specified
the pick point.
Fig. 106 Part height depending on the pick point position
Note
In the case of custom or structured production plates (with holes, grooves…), the part height entered
must be adapted to not take into account the height of the part located inside the plate.
Fig. 107 Part height depending on the production plate used
Similar to the part height, EYE+ also needs to account for the thickness of the
production plate used with the current part in order to correct the parallax effect. For a standard Asyril plate, this
is the distance between the bottom of the plate and its surface as described on
Fig. 108 for a standard Asycube 240 plate.
Fig. 108 Height measurement for a standard Asycube 240 production plate
Per default, EYE+ will set this value to the height of the standard Asyril production plate for your Asycube type as
defined in Table 22.
If the current part requires a special plate, you will need to measure the height of this plate as described in
Fig. 108 and enter the value in the production plate height field in
EYE+.
Carefully place the target on the desired pick point position. This operation must be performed carefully
because it determines the accuracy of the coordinates (X, Y) that will be sent to the robot. A set of shapes is at your disposal in the toolbox to help you align the pick point relative to any visible feature, or place it at a predefined distance from them.
Please note that the detected features are not necessarily the exact representation of the technical drawing of your
part. They can differ due to factors such as lighting, reflections, perspective, poor focus, etc.
Note
The coordinates returned by the get_part command will be directly corrected with the offset of
parallax if the camera configuration has been done properly.
Fig. 110 Feature masking for the positioning of the pick point in the middle of the circle at the maximum height of the part
The objective of the feature masking step is to define the reference features (residual features after masking)
that will be used as a model to place the pick point.
Not all features are relevant to define the reference model.
Features at the same height: Features that are not placed at the same level as the pick point must be masked
out. We only want to detect as accurately as possible those features that are at the same height as the pick point.
Adding features that are not at the same level may alter the accuracy of the positioning of the pick point due to
parallax (these features on a different level will not always have the same relative position depending on the
position of the part in the Asycube).
Reproducible features: It is essential that the reference model reflects a general description of the
candidates. Any features that are not reproducible from one candidate to another must be masked.
Enough features: There must be enough features to ensure that there is only one possible pick point
identified by the algorithm. For example, if you want to pick the part in the middle of the circle but you do not
inform the system about the circle features, there will be two possible pick point positions.
Fig. 111 Not enough features to position the pick points: 2 possibilities
The advanced options provide additional settings that can be adjusted in case the default settings do not give
good enough results, for example when some important features are not detected.
By default, EYE+ automatically determines a contrast value that is used to extract features. The contrast value of
a pixel is the gray value difference from its neighbors. If the pixel contrast exceeds the value specified, the pixel is
selected to determine the model features.
Tweaking the contrast parameter allows creating a model that has more features than the automatically-computed one. For
certain applications, it can help to precisely set the pick point.
The contrast setting can be manually set by toggling “Set contrast manually” on, as shown below:
The effect of the contrast setting is shown below:
Fig. 112 Pick point model where contrast is automatically computed by EYE+
Fig. 113 Pick point model where contrast is manually set to a lower value (e.g. 19)
Tip
The more features detected the more time it takes to run the pick angle step, remove as many features as
possible using the mask functionality.
EYE+ Studio allows for uniform scaling of the model size from 0.5x to 1.5x in the pick point positioning step. This scaling
feature is beneficial when the size of your parts varies uniformly, enabling the system to detect parts with different
sizes and keep an accurate pick point.
Adjusting the scaling values allows for better model matching on the parts when your parts sizes varies a bit, making
the pick point results more accurate. The scaling can be set differently during the pick point teaching and pick angle
teaching steps to accommodate specific needs.
The scaling setting can be manually set by toggling “Set model scaling manually” on, as shown below:
When this option is enabled, the scaling factor will be displayed in the results table, indicating the scaling
applied to parts that have been accepted.
The picture below represents a situation where the parts are rejected because the size of the model is not exactly
the same. As a result, the algorithm does not recognize the features as identical and rejects the part.
Fig. 114 Results without manual scaling activated, showing the rejected parts that could have been accepted.
The picture below represents the same situation with the scaling feature activated. With the algorithm allowed to scale the features up and down, the parts are recognized correctly and accepted despite size variations.
Fig. 115 Results with manual scaling activated, showcasing the increased number of accepted parts.
Note
While increasing the scaling range can improve recognition and accuracy, it may also negatively impact
computation time. To optimize performance, try removing as many features as possible using the mask functionality.
Note
The algorithm selects the closest match, and sometimes the accepted value may fall outside the defined range.
This is due to the nature of the vision system and how the scaling operates to optimize feature recognition.
Warning
This feature is not intended for metrology purposes.
on the desired pick point position. This operation must be performed carefully
because it determines the accuracy of the coordinates (X, Y) that will be sent to the robot. A set of shapes is at your disposal in the toolbox to help you align the pick point relative to any visible feature, or place it at a predefined distance from them.
to mask undesired features.
