Offset Strategy

This section covers the following topics:

Strategies for Single Rectangle Suction Cup

The calculation of offset setting for single rectangle suction cups is based on the combination of point cloud collision detection and the removal of the picked object’s point cloud, and it requires the point cloud data and carton dimensions in the vision result.

You can select from various offset strategies according to the actual requirement of picking.

According to the positional relationship between the suction cup and the carton group

Center Prior

Corner Prior

Corner Alignment Only

According to the directional relationship between the suction cup and the carton group

Parallel With Carton Group Long Side

Parallel With Combination Direction

Parallel With Carton Group Long Side

Note

In the illustrations below, the yellow rectangle represents the carton, and the gray rectangle represents the suction cup.

Scenario 1:

Size relationship between the carton and suction cup

Long side of the carton > Short side of the carton > Long side of the suction cup > Short side of the suction cup or Long side of the carton > Long side of the suction cup > Short side of the carton > Short side of the suction cup

Illustration
../../../../../_images/box_and_suction_cup_1.png

Actual positional relationships when picking
../../../../../_images/actual_picking_position_1.png

Offset Strategy

Any strategy is applicable.

Scenario 2:

Size relationship between the carton and suction cup

Long side of the suction cup > Short side of the suction cup > Long side of the carton > Short side of the carton

Illustration
../../../../../_images/box_and_suction_cup_2.png

Suction cup position 1
../../../../../_images/actual_picking_position_2_1.png

Suction cup position 2
../../../../../_images/actual_picking_position_2_2.png

Offset Strategy

If Center Prior is selected, position 1 instead of position 2 will be used for picking first.

If Corner Prior is selected, position 2 instead of position 1 will be used for picking first.

Scenario 3:

Size relationship between the carton and suction cup

Long side of the suction cup > Long side of the carton > Short side of the suction cup > Short side of the carton

Illustration
../../../../../_images/box_and_suction_cup_3.png

Suction cup position 1
../../../../../_images/actual_picking_position_3_1.png

Suction cup position 2
../../../../../_images/actual_picking_position_3_2.png

Suction cup position 3
../../../../../_images/actual_picking_position_3_3.png

Offset Strategy

If Center Prior is selected, position 1 will be used for picking first, and then position 2 and position 3 may be tried in order.

If the ratio of the short side of the suction cup to the long side of the carton is less than 0.25, position 1 instead of position 2 will be used for picking first.

If Corner Prior is selected, position 3 will be used for picking first, and then position 2 and position 1 may be tried in order.

If the ratio of the short side of the suction cup to the long side of the carton is less than 0.25, position 2 instead of position 1 will be used for picking first.

Scenario 4:

Size relationship between the carton and suction cup

Long side of the suction cup > Long side of the carton > Short side of the carton > Short side of the suction cup

Illustration
../../../../../_images/actual_picking_position_4_1.png

Suction cup position 1
../../../../../_images/actual_picking_position_4_1.png

Suction cup position 2
../../../../../_images/actual_picking_position_4_2.png

Offset Strategy

If Center Prior is selected, position 1 instead of position 2 will be used for picking first.

If Corner Prior is selected, position 2 instead of position 1 will be used for picking first.

Scenario 5:

Size relationship between the carton and suction cup

Long side of the carton > Long side of the suction cup > Short side of the suction cup > Short side of the carton

Illustration
../../../../../_images/box_and_suction_cup_5.png

Suction cup position 1
../../../../../_images/actual_picking_position_5_1.png

Suction cup position 2
../../../../../_images/actual_picking_position_5_2.png

Offset Strategy

If Center Prior is selected, position 1 instead of position 2 will be used for picking first.

If Corner Prior is selected, position 2 instead of position 1 will be used for picking first.

Parallel With Combination Direction

Note

In the illustrations below, the orange rectangle represents the carton, and the gray rectangle represents the suction cup.

Scenario 1:

Size relationship between the carton and suction cup

Long side of the carton > Short side of the carton > Long side of the suction cup > Short side of the suction cup or Long side of the carton > Long side of the suction cup > Short side of the carton > Short side of the suction cup

Combine suction cups along the X direction of the carton

Illustration
../../../../../_images/strategy_x_1.png

Suction cup position
../../../../../_images/strategy_x_1.png

Combine suction cups along the Y direction of the carton

Illustration
../../../../../_images/strategy_y_1.png

Suction cup position
../../../../../_images/strategy_y_1.png

Offset Strategy

Any strategy is applicable.

Scenario 2:

Size relationship between the carton and suction cup

Long side of the suction cup > Short side of the suction cup > Long side of the carton > Short side of the carton or Long side of the suction cup > Long side of the carton > Short side of the suction cup > Short side of the carton

Combine suction cups along the X direction of the carton

Illustration
../../../../../_images/strategy_x_2.png

Suction cup position 1
../../../../../_images/strategy_x_2.png

Suction cup position 2
../../../../../_images/picking_position_x_2.png

Combine suction cups along the Y direction of the carton

Illustration
../../../../../_images/strategy_y_2.png

Suction cup position 1
../../../../../_images/strategy_y_2.png

Suction cup position 2
../../../../../_images/picking_position_y_2.png

Offset Strategy

If Center Prior is selected, position 1 instead of position 2 will be used for picking first.

If Corner Prior is selected, position 2 instead of position 1 will be used for picking first.

Scenario 3:

Size relationship between the carton and suction cup

Long side of the suction cup > Long side of the carton > Short side of the carton > Short side of the suction cup

Combine suction cups along the X direction of the carton

Illustration
../../../../../_images/strategy_x_3.png

Suction cup position 1
../../../../../_images/strategy_x_3.png

Suction cup position 2
../../../../../_images/picking_position_x_3.png

Combine suction cups along the Y direction of the carton

Illustration
../../../../../_images/strategy_y_3.png

Suction cup position 1
../../../../../_images/strategy_y_3.png

Suction cup position 2
../../../../../_images/picking_position_y_3.png

Offset Strategy

If Center Prior is selected, position 1 instead of position 2 will be used for picking first.

If Corner Prior is selected, position 2 instead of position 1 will be used for picking first.

Scenario 4:

Size relationship between the carton and suction cup

Long side of the carton > Long side of the suction cup > Short side of the suction cup > Short side of the carton

Combine suction cups along the X direction of the carton

Illustration
../../../../../_images/strategy_x_4.png

Suction cup position 1
../../../../../_images/strategy_x_4.png

Suction cup position 2
../../../../../_images/picking_position_x_4.png

Combine suction cups along the Y direction of the carton

Illustration
../../../../../_images/strategy_y_4.png

Suction cup position 1
../../../../../_images/strategy_y_4.png

Suction cup position 2
../../../../../_images/picking_position_y_4.png

Offset Strategy

If Center Prior is selected, position 1 instead of position 2 will be used for picking first.

If Corner Prior is selected, position 2 instead of position 1 will be used for picking first.

Strategies for Parallel Suction Cups

The offset strategies for parallel suction cups are different from that of single rectangle suction cups. Only one offset setting is available when Parallel Suction Cups is set as the Multi Pick Suction Cup Type, and it entirely depends on the vision result (except point clouds) and carton dimensions provided by the vision service. If the carton is not detected or the dimensions provided by the vision service are wrong, the calculation of the offset setting will be incorrect.

Compared with the offset strategies for a single rectangle suction cup, the offset strategy for parallel suction cups can be considered as a Corner Prior offset strategy when the long side of the suction cup is parallel with the direction of the carton group. However, unlike the single rectangle suction cup, each corner of the suction cup sections will be involved in the calculation of the offset setting.

The following example is based on parallel suction cups that contain four sections. The yellow rectangle represents the carton, and the gray rectangle represents the suction cup.

Offset Strategy: Corner Prior + Long side of the suction cup is parallel with the direction of the carton group

Possible suction cup positions: 12 in total, as shown below:

../../../../../_images/picking_position_12.png

Each section of the parallel suction cups can be started independently. In actual application, even part of the suction cups covers objects that are not supposed to be picked, as long as the suction cup section is not started, those objects will not be picked.