The multi-pick functionality does exactly what it sounds like, and enables Pally to pick up multiple units of product at a time. Thus, palletize more than one unit each cycle. This is beneficial in numerous ways. To be able to discuss how and why effectively, there are two important acronyms to understand:

• CPM
  Cases Per Minute: The number of cases/product to palletize each minute.

• Cycles/min
  Cycles Per Minute: How many palletizing cycles are performed each minute. A cycle is defined as an entire pick and place task, i.e., from starting the pickup when the product(s) are ready at the pickup position, to placing the product(s) on the pallet, to finally returning to the above pickup position.

Pally processes specific box-, pattern-, and movement information to calculate the most efficient method to pick boxes. It calculates when to pick 1, 2, 3, or more boxes and can switch between each lift. Calculations are done in milliseconds and will not affect the robot's speed (The maximal multi-grip limit is 8 boxes per lift). The multi-pick limit is set when creating your pattern in the pallet builder.

If optimal gripper orientation at pick-up is defined in the URCap, Pally will also rotate the gripper to pick the boxes the smartest way, e.g., to get better reach or to have a faster placement of the box on the pallet.

You don’t need to program anything on the robot to use multi-pick. Pally does that, and the pallet builder creates the pattern file.

The benefits of picking multiple units are numerous, as long as the payload, integrity, and the sheer size of the product allow it for the specific palletizing system.

• Improved safety by having the robot move more slowly while still meeting your requirements

• Improved efficiency by always picking the most suitable number of boxes

• Improved speed by multi-picking boxes when possible

• More flexible patterns, compared to other palletizing URCaps, you are not limited to single- or multi-pick

At production lines where the required CPM is higher than the available cycles/min, multi-pick is a good solution.

When palletizing small products, the farthest corner of the pallet may be hard to reach for smaller robots. Depending on the robot, the gripper, the pallet size, and the distance from the robot base. A system engineered for multi-pick will often utilize a gripper that provides a certain offset between some of the products and the robot tool flange, which in turn can be used to increase range.

Given that the products can be gripped and moved safely, multi-pick will increase safety because the robot can operate at lower speeds. The more product units a robot is allowed to palletize per cycle, the fewer cycles/min it can complete while maintaining a high CPM. Thus, a cycle can be allowed to take more time, enabling speed reduction.

The Physics
When an object is moving, the kinetic energy of the object is quadratic (exponential with the factor of 2) to the velocity, while only linear to the mass. Thus, if velocity can be reduced by increasing mass (pick more units), it will decrease the amount of kinetic energy in the palletizing system significantly. Hence, the kinetic energy dissipated in a collision is also reduced. With less energy to dissipate, the impact force between the product and the object or person with whom it collides is reduced. This effect is increased even further by taking the mass of the robot and the gripper into account, making Multi Pick even more advantageous. A unitary representation of how kinetic energy increases with mass and velocity can be seen in the graph below.

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While Pally accommodates multi-pick, the system HW must be engineered to do so. That being said, most palletizers running on Pally can multi-pick. How many cases in each pick depends on:

• Product Sensors: One sensor is required per product to be picked.

• Payload: The gripper must be strong enough to grip the product, and the robot must be strong enough to carry it.

• Gripper: The gripper must be able to obtain a firm grip on all units in each pick.

Each product unit to be gripped in a single pick must have a dedicated product sensor. These sensors are necessary to keep Pally informed of how many products are available at the pickup positions. Thus, if a maximum of four units is to be picked each cycle, the line must be equipped with four product sensors.

Example
In the image below, a very standard Pally palletizing system is displayed. It utilizes robot, two product sensors, and a gripper. Due to the two product sensors, this setup can multi-pick up to two products each cycle.

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The payload of the product and the gripper will, in many cases, define how many products can be palletized at once. To grip more products in a single pick, a bigger gripper might be necessary, potentially increasing gripper weight, thus reducing the amount of product in the payload.
Multi-pick can often be used with a standard gripper, such as the Schmaltz FXCB or Unigripper Co/Light. In other words, a palletizing system, even if it is not specifically customized for it, can multi-pick products, depending on the payload and product size (see the subchapter below on gripper size and grip quality).

The gripper chosen for the project must be large enough to reach all the product units in each pick, while also providing good grip quality to safely palletize them. Good grip quality is mainly a product of two features: Strength and stability. Not only must the gripper be strong enough to carry each unit of product, but it must also provide sufficient stability during the movements.

As mentioned above, regarding payload, most palletizing systems using Pally can multi-pick. When the HW is installed, it is really only dependent on the specific product size and payload, whether multi-pick can/ should be applied or not.

The multi-pick functionality is native in Pally. Whether to use it or not is configured in each pallet pattern. This is achieved by defining the number of product units Pally is allowed to pick each cycle. If it is necessary to pick fewer units in one or more cycles to complete the pattern, Pally will automatically do so.

When creating a new pattern, you can choose max multigrip, or you can choose to set it to auto.

If you choose auto, Pally will calculate how many boxes it picks up at each cycle.

If you set it to a number that limits Pally to the maximum pick, that particular number of items will be picked in each cycle.

Please do remember that you need to set “Box padding” to 0 if you want multi-pick.

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