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Robots picking items in Amazon’s warehouses need to be able to handle millions of different items of various shapes, sizes and weights. Right now, the company primarily uses suction grippers, which use air and a tight seal to lift items, but Amazon’s robotics team is developing a more flexible gripper to reliably pick up items suction grippers struggle to pick.

Amazon is teaching robots how to understand cluttered environments in three dimensions, locate specific items and pick them using a pinch grasp, or a thumb and finger hold. The company’s current vacuum-like grippers use elastic suction cups that form to the surface of an item. This creates a tight seal that allows the robot to pick objects.

Amazon said this method works great for flat items that only require one point of contact for picking, like rulers or cards. It’s less effective, Amazon said, for items that require more than one point of contact to pick up, for example, a book will fly open if you pick it from just the front or back cover.

Suction grippers also struggle to get a tight seal on bags filled with granular items, like marbles, according to Amazon. And even on items these grippers can pick up well, if the angle of attachment changes because of the momentum of the robot arm swinging it from one place to another, then the seal will break too early and the robot drops the item.

These cases are why Amazon is interested in the pinch-grasp method. Despite how natural it is for humans, it’s not a simple one to develop in a robot. To teach a robot to pick items out of piles of other items using this method, researchers first needed to teach it to be able to estimate the shape of items that could be partially obscured by other items.

As humans, we do this without even thinking about it, but robots have a much harder time understanding the whole shape of an item if they can’t see all of it. Amazon’s robots gauge what they’re picking by using multiple camera angles and machine learning models trained to recognize and estimate the shape of individual items. The robot uses this to decide how to best grasp the item on two surfaces.

Once the robot makes those observations, it uses a set of motion algorithms to combine the information it gathered about the scene and the item with the known dynamics of the robot to calculate how to move the item from one place to another.

The robot also continues to use its multiple-angle view of the situation throughout the pick. This is another deviation from typical picking methods, where a robot won’t usually continue to look at the scene as it carries out a pick.

So far, Amazon’s team has seen encouraging success with its pinch-grasping robots. A prototype robot achieved a 10-fold reduction in damage on certain items, like books, without slowing down operations, Amazon said.

Despite this, Amazon still sees room for improvement. The team is currently using an off-the-shelf gripper that can only pick items that weigh less than 2 lbs. This makes the gripper capable of handling only half of the items that Amazon has available for purchase. Going forward, the team plans to design its own gripper for the job. 

In the future, Amazon hopes that it can implement its pinch-grasping robot alongside its current suction ones so that it can decide which robot would be best suited to picking each individual item. The company is using a similar strategy with its Proteus autonomous mobile robot (AMR). 

Amazon unveiled Proteus in June 2022, expanding its already extensive robotics ecosystem. The company had already been using automated guided vehicles (AGVs) in its warehouses for a decade, but these AGVs only work in caged-off spaces. 

While both of the robots perform similar tasks, sliding under Amazon’s GoCarts to pick them up and move them across the warehouse, Proteus gives the company greater flexibility because of its ability to work freely and safely around people. The company plans to continue using both robots going forward. 

Amazon recently announced that it agreed to acquire Cloostermans, a Belgium-based company that specializes in mechatronics. Cloostermans has been selling products to Amazon since at least 2019, including technology Amazon uses in its operation to move and stack heavy pallets and totes and robots to package products for customer orders.