Pally General - Waypoints and Path Planning

Pally uses the following waypoints from picking up a product to placing it on the pallet.

Pickup position → Box free height → Smart exit → Pally generated waypoints → Approach distance → Target position

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Pally uses the following waypoints from placing the product on the pallet to returning to pick up a new product.

Target position → Vertical exit point → Pally generated waypoints → Smart exit → Above Pickup - Pickup position

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This position is a result of both the product, the multi-pick calculation, and the gripper orientation at pickup.

This is a position straight above the pickup position. The added height needs to equal the height Pally needs to lift the box to avoid hitting items on the conveyor, like guides, sensors, etc. This position needs to be fixed, unless you want Pally to recalculate it to another value at runtime.

This is a rectangular area where Pally will move the TCP within before moving towards the target area on the pallet. This area is used to avoid crashing with the conveyor, frame, already placed boxes, and any other physical object in the proximity of the palletizing cell.

These are waypoints that Pally automatically generates to create a smooth movement between the smart exit and the target position on the pallet.

The waypoint is where the diagonal movement towards the box’s target position on the pallet will be initiated. The distance is given relative to the target position in all three directions. (X, Y, Z)

If you do not check the ‘fixed’ checkbox, Pally may recalculate the approach distance to a different value than what’s given.

Check the ‘fixed’ checkbox to force Pally to use the approach distance specified. This will also result in Pally completing the rotation of the box earlier, before moving towards the target position on the pallet.

As the robot enters the approach distance, the speed will be lowered, as this is typically an area that requires greater accuracy.

You can use the variable to set the approach distance as you like. You can change the distances to your own needs, and we recommend doing it in the onNextTask callback.

If you check the “fixed” checkbox, Pally changes the path planning and adds an extra waypoint to complete rotation before moving towards the target position, see picture below.

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This is where Pally will place the product on the pallet

After placing the product, Pally moves vertically upwards before moving away from the target area.

Gripper distance from the top of the box, from where the robot will move down vertically until the gripper reaches the box surface.

The blow function will be active from the above pickup waypoint to the pickup position to remove potential dust on top of the box.

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This is the waypoint where Pally waits while new boxes come into the pickup position. We recommend placing this close to the Above pickup waypoint to avoid unnecessary movement.

The path planning algorithm is a crucial component of the Pally solution. It calculates the optimal movement from the pickup position to the target position on the pallet and back again. These calculations are performed dynamically when the robot moves one or more boxes from the pickup to the pallet position. It combines the waypoints listed above with the features listed below.

You set these settings on the pattern when you create it in the Pallet builder.

This option provides the shortest path from the pick position to the pallet position. To maximize robot reach, use this option.

Pros:

• Shortest path

• Best reach

Cons:

• Possible collision with the mounting base

This option introduces a longer path to avoid collisions with the mounting base. The boxes will be moved above all other boxes on the pallet, and the approach point is further away than the actual target position. Use this option to avoid collision with the mounting base.

Pros:

• Guaranteed distance to the mounting base

• Avoid crashes with existing boxes because the inverted approach will create a path where you move above the existing layer before moving to the target position

• Avoid crashes with the conveyor in tight paths because you move in an outward path before you move back in to place the product at the target position

Cons:

• Longer path

• Limited reach

• Lower CPM (you will lose approx 5-6 % cycles per minute)

Combining the normal and inverted approach

Palletizing the lower and upper layers often requires different box orders and path planning.

In the lower layers, there is a risk of collision between the robot arm and the mounting base. In the upper layers, there is a limited robot reach available. To balance these limitations, you can set an inverted approach on lower layers and a normal approach on higher layers.

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This value ranges from 0% to 100%. It determines how high above the other boxes the path planning algorithm will move the box. Lower values let the box move closer to the top of the other boxes on the pallet; higher values keep the box closer to the box’s free height.

The high approach boost only affects boxes placed below the box-free position.